A three-dimensional transient mixed hybrid finite element model for superabsorbent polymers with strain-dependent permeability.

PubMed

Yu, Cong; Malakpoor, Kamyar; Huyghe, Jacques M

2018-05-16

A hydrogel is a cross-linked polymer network with water as solvent. Industrially widely used superabsorbent polymers (SAP) are partially neutralized sodium polyacrylate hydrogels. The extremely large degree of swelling is one of the most distinctive characteristics of such hydrogels, as the volume increase can be about 30 times its original volume when exposed to physiological solution. The large deformation resulting from the swelling demands careful numerical treatment. In this work, we present a biphasic continuum-level swelling model using the mixed hybrid finite element method (MHFEM) in three dimensions. The hydraulic permeability is highly dependent on the swelling ratio, resulting in values that are orders of magnitude apart from each other. The property of the local mass conservation of MHFEM contributes to a more accurate calculation of the deformation as the permeability across the swelling gel in a transient state is highly non-uniform. We show that the proposed model is able to simulate the free swelling of a random-shaped gel and the squeezing of fluid out of a swollen gel. Finally, we make use of the proposed numerical model to study the onset of surface instability in transient swelling.

Effects of a novel poly (AA-co-AAm)/AlZnFe₂O₄/potassium humate superabsorbent hydrogel nanocomposite on water retention of sandy loam soil and wheat seedling growth.

PubMed

Shahid, Shaukat Ali; Qidwai, Ansar Ahmad; Anwar, Farooq; Ullah, Inam; Rashid, Umer

2012-10-25

A novel poly(acrylic acid-co-acrylamide)AlZnFe₂O₄/potassium humate( )superabsorbent hydrogel nanocomposite (PHNC) was synthesized and its physical properties characterized using SEM, Energy Dispersive X-ray (EDX) and FTIR spectroscopic techniques. Air dried sandy loam soil was amended with 0.1 to 0.4 w/w% of PHNC to evaluate its soil moisture retention attributes. Effect of PHNC amendment on pH, electrical conductivity (EC), porosity, bulk density and hydraulic conductivity of sandy loam soil was also studied. The soil amendment with 0.1 to 0.4 w/w% of PHNC remarkably enhanced the moisture retention at field capacity as compared to the un-amended soils. Seed germination and seedling growth of wheat (Triticum aestivum L.) was considerably increased and a delay by 6-9 days in wilting of seedlings was observed in the soil amended with PHNC, resulting in improved wheat plant establishment and growth.

Experimental study of porous media flow using hydro-gel beads and LED based PIV

NASA Astrophysics Data System (ADS)

Harshani, H. M. D.; Galindo-Torres, S. A.; Scheuermann, A.; Muhlhaus, H. B.

2017-01-01

A novel experimental approach for measuring porous flow characteristics using spherical hydro-gel beads and particle image velocimetry (PIV) technique is presented. A transparent porous medium consisting of hydro-gel beads that are made of a super-absorbent polymer, allows using water as the fluid phase while simultaneously having the same refractive index. As a result, a more adaptable and cost effective refractive index matched (RIM) medium is created. The transparent nature of the porous medium allows optical systems to visualize the flow field by using poly-amide seeding particles (PSP). Low risk light emitting diode (LED) based light was used to illuminate the plane in order to track the seeding particles’ path for the characterization of the flow inside the porous medium. The system was calibrated using a manually measured flow by a flow meter. Velocity profiles were obtained and analysed qualitatively and quantitatively in order to characterise the flow. Results show that this adaptable, low risk experimental set-up can be used for flow measurements in porous medium under low Reynolds numbers. The limitations of using hydro-gel beads are also discussed.

Slow-release NPK fertilizer encapsulated by carboxymethyl cellulose-based nanocomposite with the function of water retention in soil.

PubMed

Olad, Ali; Zebhi, Hamid; Salari, Dariush; Mirmohseni, Abdolreza; Reyhani Tabar, Adel

2018-09-01

In this study, new slow release fertilizer encapsulated by superabsorbent nanocomposite was prepared by in-situ graft polymerization of sulfonated-carboxymethyl cellulose (SCMC) with acrylic acid (AA) in the presence of polyvinylpyrrolidone (PVP), silica nanoparticles and nitrogen (N), phosphorous (P), and potassium (K) (NPK) fertilizer compound. The prepared materials were characterized by FT-IR, XRD and scanning electron microscopy (SEM) techniques. The incorporation of NPK fertilizer into hydrogel nanocomposite network was verified by results of these analyses. Also, the swelling behavior in various pH and saline solutions as well as water retention capability of the prepared hydrogel nanocomposite was evaluated. The fertilizer release behavior of the NPK loaded hydrogel nanocomposite was in good agreement with the standard of Committee of European Normalization (CEN), indicating its excellent slow release property. These good characteristics revealed that the hydrogel nanocomposite fertilizer formulation can be practically used in agricultural and horticultural applications. Copyright © 2018 Elsevier B.V. All rights reserved.

A volatile tracer-assisted headspace analytical technique for determining the swelling capacity of superabsorbent polymers.

PubMed

Zhang, Shu-Xin; Jiang, Ran; Chai, Xin-Sheng

2017-09-01

This paper reports on a new method for the determination of swelling capacity of superabsorbent polymers by a volatile tracer-assisted headspace gas chromatography (HS-GC). Toluene was used as a tracer and added to the solution for polymers swelling test. Based on the differences of the tracer partitioned between the vapor and hydrogel phase before and after the polymer's swelling capacity, a transition point (corresponding to the material swelling capacity) can be observed when plotting the GC signal of toluene vs. the ratio of solution added to polymers. The present method has good precision (RSD<2.1%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 8.0%. The present method is very suitable to be used for testing the swelling capacity of polymers at the elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres.

PubMed

Bhattacharya, Shiv Sankar; Mazahir, Farhan; Banerjee, Subham; Verma, Anurag; Ghosh, Amitava

2013-10-15

Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application. Copyright © 2013 Elsevier Ltd. All rights reserved.

Starch hydrogels: The influence of the amylose content and gelatinization method.

PubMed

Biduski, Bárbara; Silva, Wyller Max Ferreria da; Colussi, Rosana; Halal, Shanise Lisie de Mello El; Lim, Loong-Tak; Dias, Álvaro Renato Guerra; Zavareze, Elessandra da Rosa

2018-07-01

Gelatinization and retrogradation, influenced by amylose and amylopectin ratio, are important characteristics for starch hydrogels elaboration. The objective of this study was to evaluate the influence of amylose content and the gelatinization method on the physicochemical characteristics of native and cross-linked rice starch hydrogels. The native and cross-linked starches were gelatinized with heating or alkaline solution, added polyvinyl alcohol, frozen and then freeze-dried. The cross-linked starch had a low final viscosity (101.38 RVU), which made the heat-induced gelatinized hydrogel readily disintegrated in water. However, modified starch hydrogels obtained by alkaline-induced gelatinization resulted in a more rigid structure than the native starch hydrogels. In addition, the starch sample with high amylose content had lower water absorption (322.2%) due to the greater stiffness of the hydrogel structure that resisted swelling. The alkaline-gelatinization resulted in stiffer hydrogels with lower water absorption (322.2 to 534.8%), while the heat-gelatinized behaved as a superabsorbent (658.7 to 1068.5%). The variability of the hydrogels properties of this study can enable a range of applications due to different amylose contents and gelatinization methods. Copyright © 2018 Elsevier B.V. All rights reserved.

Superporous thermo-responsive hydrogels by combination of cellulose fibers and aligned micropores.

PubMed

Halake, Kantappa S; Lee, Jonghwi

2014-05-25

In the area of artificial hydrogels, simultaneous engineering of the volume transition characteristics and mechanical properties of stimuli-responsive hydrogels is an important subject. By unrestricted architecting of hierarchical structures, natural hydrogels are able to provide a wide range of swelling and mechanical properties, beyond the limits of artificial hydrogels. Herein, a combination of nanostructures and microstructures was developed to construct superporous hydrogels. Fibers of microfibrillated cellulose (MFC), an eco-friendly reinforcing material, were used as nanostructures, aligned micropores were used as microstructures, and in situ photopolymerization was used to immobilize the two structures together within the gel networks of poly(N-isopropyl acrylamide) (PNIPAm). The introduction of MFC distinctly enhanced volume transition, mainly by decreasing the swelling ratios above the transition. The introduction of directional micropores increased the swelling ratio below the transition and decreased the swelling ratio above the transition, thereby also enhancing the volume transition. Additionally, the formation of aligned micropores achieved fast water infiltration, which is beneficial for superabsorbent applications. The introduction of aligned micropores reduced the elastic modulus, but this could partially be compensated for by reinforcement with MFC. This combination of crystalline nanofibers and aligned micropores has great potential for the development of stimuli-responsive superporous hydrogels outperforming current artificial hydrogels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Toxicity associated with ingestion of a polyacrylic acid hydrogel dog pad.

PubMed

Dorman, David C; Foster, Melanie L; Olesnevich, Brooke; Bolon, Brad; Castel, Aude; Sokolsky-Papkov, Marina; Mariani, Christopher L

2018-06-01

Superabsorbent sodium polyacrylate polymeric hydrogels that retain large amounts of liquids are used in disposable diapers, sanitary napkins, and other applications. These polymers are generally considered "nontoxic" with acute oral median lethal doses (LD 50 ) >5 g/kg. Despite this favorable toxicity profile, we identified a novel toxic syndrome in dogs and rats following the ingestion of a commercial dog pad composed primarily of a polyacrylic acid hydrogel. Inappropriate mentation, cerebellar ataxia, vomiting, and intention tremors were observed within 24 h after the ingestion of up to 15.7 g/kg of the hydrogel by an adult, castrated male Australian Shepherd mix. These observations prompted an experimental study in rats to further characterize the toxicity of the hydrogel. Adult, female Sprague Dawley rats ( n = 9) were assessed before and after hydrogel ingestion (2.6-19.2 g/kg over 4 h) using a functional observation battery and spontaneous motor activity. Clinical signs consistent with neurotoxicity emerged in rats as early as 2 h after the end of hydrogel exposure, including decreased activity in an open field, hunched posture, gait changes, reduced reaction to handling, decreased muscle tone, and abnormal surface righting. Hydrogel-exposed rats also had reduced motor activity when compared with pre-exposure baseline data. Rats that ingested the hydrogel did not develop nervous system lesions. These findings support the conclusion that some pet pad hydrogel products can induce acute neurotoxicity in animals under high-dose exposure conditions.

Superabsorbent hydrogels via graft polymerization of acrylic acid from chitosan-cellulose hybrid and their potential in controlled release of soil nutrients.

PubMed

Essawy, Hisham A; Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F

2016-08-01

Superabsorbent polymers fabricated via grafting polymerization of acrylic acid from chitosan (CTS) yields materials that suffer from poor mechanical strength. Hybridization of chitosan with cellulose (Cell) via chemical bonding using thiourea formaldehyde resin increases the flexibility of the produced hybrid (CTS/Cell). The hybridization process and post graft polymerization of acrylic acid was followed using Fourier transform infrared (FTIR). Also, the obtained structures were homogeneous and exhibited uniform surface as could be shown from imaging with scanning electron microscopy (SEM). Thus, the polymers derived from the grafting of polyacrylic acid from (CTS/Cell) gave rise to much more mechanically robust structures ((CTS/Cell)-g-PAA) that bear wide range of pH response due to presence of chitosan and polyacrylic acid in one homogeneous entity. Additionally, the obtained structures possessed greater water absorbency 390, 39.5g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced retention potential even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high grafting efficiency (GE%), 86.4%, and grafting yield (GY%), 750%. The new superabsorbent polymers proved to be very efficient devices for controlled release of fertilizers into the soil which expands their use in agriculture and horticultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

“Nanofiltration” Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples

NASA Astrophysics Data System (ADS)

Xie, Xing; Bahnemann, Janina; Wang, Siwen; Yang, Yang; Hoffmann, Michael R.

2016-02-01

Detection and quantification of pathogens in water is critical for the protection of human health and for drinking water safety and security. When the pathogen concentrations are low, large sample volumes (several liters) are needed to achieve reliable quantitative results. However, most microbial identification methods utilize relatively small sample volumes. As a consequence, a concentration step is often required to detect pathogens in natural waters. Herein, we introduce a novel water sample concentration method based on superabsorbent polymer (SAP) beads. When SAP beads swell with water, small molecules can be sorbed within the beads, but larger particles are excluded and, thus, concentrated in the residual non-sorbed water. To illustrate this approach, millimeter-sized poly(acrylamide-co-itaconic acid) (P(AM-co-IA)) beads are synthesized and successfully applied to concentrate water samples containing two model microorganisms: Escherichia coli and bacteriophage MS2. Experimental results indicate that the size of the water channel within water swollen P(AM-co-IA) hydrogel beads is on the order of several nanometers. The millimeter size coupled with a negative surface charge of the beads are shown to be critical in order to achieve high levels of concentration. This new concentration procedure is very fast, effective, scalable, and low-cost with no need for complex instrumentation.

"Nanofiltration" Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples.

PubMed

Xie, Xing; Bahnemann, Janina; Wang, Siwen; Yang, Yang; Hoffmann, Michael R

2016-02-15

Detection and quantification of pathogens in water is critical for the protection of human health and for drinking water safety and security. When the pathogen concentrations are low, large sample volumes (several liters) are needed to achieve reliable quantitative results. However, most microbial identification methods utilize relatively small sample volumes. As a consequence, a concentration step is often required to detect pathogens in natural waters. Herein, we introduce a novel water sample concentration method based on superabsorbent polymer (SAP) beads. When SAP beads swell with water, small molecules can be sorbed within the beads, but larger particles are excluded and, thus, concentrated in the residual non-sorbed water. To illustrate this approach, millimeter-sized poly(acrylamide-co-itaconic acid) (P(AM-co-IA)) beads are synthesized and successfully applied to concentrate water samples containing two model microorganisms: Escherichia coli and bacteriophage MS2. Experimental results indicate that the size of the water channel within water swollen P(AM-co-IA) hydrogel beads is on the order of several nanometers. The millimeter size coupled with a negative surface charge of the beads are shown to be critical in order to achieve high levels of concentration. This new concentration procedure is very fast, effective, scalable, and low-cost with no need for complex instrumentation.

“Nanofiltration” Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples

PubMed Central

Xie, Xing; Bahnemann, Janina; Wang, Siwen; Yang, Yang; Hoffmann, Michael R.

2016-01-01

Detection and quantification of pathogens in water is critical for the protection of human health and for drinking water safety and security. When the pathogen concentrations are low, large sample volumes (several liters) are needed to achieve reliable quantitative results. However, most microbial identification methods utilize relatively small sample volumes. As a consequence, a concentration step is often required to detect pathogens in natural waters. Herein, we introduce a novel water sample concentration method based on superabsorbent polymer (SAP) beads. When SAP beads swell with water, small molecules can be sorbed within the beads, but larger particles are excluded and, thus, concentrated in the residual non-sorbed water. To illustrate this approach, millimeter-sized poly(acrylamide-co-itaconic acid) (P(AM-co-IA)) beads are synthesized and successfully applied to concentrate water samples containing two model microorganisms: Escherichia coli and bacteriophage MS2. Experimental results indicate that the size of the water channel within water swollen P(AM-co-IA) hydrogel beads is on the order of several nanometers. The millimeter size coupled with a negative surface charge of the beads are shown to be critical in order to achieve high levels of concentration. This new concentration procedure is very fast, effective, scalable, and low-cost with no need for complex instrumentation. PMID:26876979

Recent advances in clay mineral-containing nanocomposite hydrogels.

PubMed

Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

2015-12-28

Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

Superabsorbent hydrogels coating increased degradation and decreased bound residues formation of carbendazim in soil.

PubMed

Yang, Yatian; Zhang, Sufen; Yang, Jingying; Bai, Chan; Tang, Shenghua; Ye, Qingfu; Wang, Haiyan

2018-07-15

The intensive use of pesticides has caused serious environmental pollution and ecological issues. Thus, it is imperative to explore an efficient way to minimize the pesticide residues and pollution. In the present study, we employed the superabsorbent hydrogels (SHs)-coated pesticide 14 C-carbendazim (H- 14 C-MBC) to investigate the fate of MBC in aerobic soils and to assess the soil microbial state during incubation. The results showed that after coating with SHs, MBC dissipation was improved significantly by 34.2-54.1% compared with that in the control (p<0.05), reducing the persistence of MBC in soil matrix. At 100d, the release of 14 C-CO 2 was enhanced by 68.0% and 46.6% in neutral loamy soil and basic saline soil, respectively, with respect to the control, resulting in more complete degradation and detoxification of MBC. Additionally, the bound residue in soils, which was associated with potential environmental risk and pollution, was reduced by 15.2% and 14.2%, respectively, compared with that in control soils. The microbial diversity of post-H- 14 C-MBC soil varied, and microbial composition and abundance remained different from the control, even with the refreshment of soil stability and fertility compared with the blank soil. These results demonstrate the environmental behavior of SHs-coated MBC in soils, and illustrate that SHs-encapsulated formulations would be a promising measure for reducing the soil-residue pollution and environmental risk of pesticides. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation of fast response superabsorbent hydrogels by radiation polymerization and crosslinking of N-isopropylacrylamide in solution

NASA Astrophysics Data System (ADS)

Abd El-Mohdy, H. L.; Safrany, Agnes

2008-03-01

Macroporous temperature-responsive poly( N-isopropylacrylamide) (PNIPAAm) hydrogels with high equilibrium swelling and fast response rates were obtained by a 60Co γ- and electron beam (EB) irradiation of aqueous N-isopropylacrylamide (NIPAAm) monomer solutions. The effect of irradiation temperatures, the dose, the addition of a pore-forming agent on the swelling ratio, and the kinetics of swelling and shrinking of the PNIPAAm gels was studied. The gels synthesized above the LCST exhibited the highest equilibrium swelling (300-400) and fastest response rate measured by minutes. Scanning electron microscope (SEM) pictures revealed that the gels synthesized above the LCST have larger pores than those prepared at temperatures below the LCST. The gels showed a reversible response to cyclical changes in temperature and might be used in a pulsed drug delivery device. The gels synthesized above the LCST exhibited the highest testosterone propionate release.

Hydrothermal Conditioning of Physical Hydrogels Prepared from a Midblock-Sulfonated Multiblock Copolymer

DOE PAGES

Mineart, Kenneth P.; Dickerson, Joshua D.; Love, Dillon M.; ...

2017-01-24

Since nanostructured amphiphilic macromolecules capable of affording high ion and water transport are becoming increasingly important in a wide range of contemporary energy and environmental technologies, the swelling kinetics and temperature dependence of water uptake are investigated in a series of midblock-sulfonated thermoplastic elastomers. Upon self-assembly, these materials maintain a stable hydrogel network in the presence of a polar liquid. In this study, real-time water-sorption kinetics in copolymer films prepared by different casting solvents are elucidated by synchrotron small-angle X-ray scattering and gravimetric measurements, which directly correlate nanostructural changes with macroscopic swelling to establish fundamental structure-property behavior. By monitoring themore » equilibrium swelling capacity of these materials over a range of temperatures, an unexpected transition in the vicinity of 50 degrees C has been discovered. Furthermore, depending on copolymer morphology and degree of sulfonation, hydrothermal conditioning of specimens to temperatures above this transition permits retention of superabsorbent swelling at ambient temperature.« less

Water- and Fertilizer-Integrated Hydrogel Derived from the Polymerization of Acrylic Acid and Urea as a Slow-Release N Fertilizer and Water Retention in Agriculture.

PubMed

Cheng, Dongdong; Liu, Yan; Yang, Guiting; Zhang, Aiping

2018-05-31

To reduce the preparation cost of superabsorbent and improve the N release rate at the same time, a novel low-cost superabsorbent (SA) with the function of N slow release was prepared by chemical synthesis with neutralized acrylic acid (AA), urea, potassium persulfate (KPS), and N, N'-methylenebis(acrylamide) (MBA). The order of influence factors on the water absorbency property was determined by an orthogonal L 18 (3) 7 experiment. On the basis of the optimization results of the orthogonal experiment, the effects of a single factor on the water absorption were investigated, and the highest water absorbency (909 g/g) was achieved for the conditions of 1.0 mol urea/mol AA ratio, 100% of AA neutralized, K + , 1.5% KPS to AA mass fraction, 0.02% MBA to AA mass fraction, 45 °C reaction temperature, and 4.0 h reaction time. The optimal sample was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behaviors of the superabsorbent were investigated in distilled water and various soil and salt solutions. The water-release kinetics of SA in different negative pressures and soils were systematically investigated. Additionally, the maize seed germination in various types of soil with different amounts of SA was proposed, and the N could release 3.71% after being incubated in distilled water for 40 days. After 192 h, the relative water content of SA-treated sandy loam, loam, and paddy soil were 42, 56, and 45%, respectively. All of the results in this work showed that SA had good water retention and slow N-release properties, which are expected to have potential applications in sustainable modern agriculture.

Starch derivative-based superabsorbent with integration of water-retaining and controlled-release fertilizers.

PubMed

Zhong, Kang; Lin, Zuan-Tao; Zheng, Xi-Liang; Jiang, Gang-Biao; Fang, Yu-Sheng; Mao, Xiao-Yun; Liao, Zong-Wen

2013-02-15

Phosphate rock (PHR), a traditional fertilizer, is abundant, but is hard to be utilized by plants. To improve the utilization of PHR, and to integrate water-retaining and controlled-release fertilizers, an agricultural superabsorbent polymer based on sulfonated corn starch/poly (acrylic acid) embedding phosphate rock (SCS/PAA/PHR) was prepared. PHR can be suspended and well-dispersed in SCS/PAA by sulfonated corn starch (SCS). PHR and KOH were mixed in acrylic acid solution to provide phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent were investigated. The maximum swelling capacity in distilled water or 0.9 wt.% (weight percent) NaCl solution reached 498 g g(-1) and 65 g g(-1) (water/prepared dry superabsorbent) respectively. Moreover, release behaviours of P and K in SCS/PAA/PHR were also investigated. The results showed that SCS/PAA/PHR possessed excellent sustained-release property of plant nutrient, and the SCS/PAA could improve the P release greatly. Besides, the XPS analysis was employed to study the relationship between PHR and superabsorbent polymer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Superabsorbent biphasic system based on poly(lactic acid) and poly(acrylic acid)

NASA Astrophysics Data System (ADS)

Sartore, Luciana; Pandini, Stefano; Baldi, Francesco; Bignotti, Fabio

2016-05-01

In this research work, biocomposites based on crosslinked particles of poly(acrylic acid), commonly used as superabsorbent polymer (SAP), and poly-L-lactic acid (PLLA) were developed to elucidate the role of the filler (i.e., polymeric crosslinked particles) on the overall physico-mechanical behavior and to obtain superabsorbent thermoplastic products. Samples prepared by melt-blending of components in different ratios showed a biphasic system with a regular distribution of particles, with diameter ranging from 5 to 10 μm, within the PLLA polymeric matrix. The polymeric biphasic system, coded PLASA i.e. superabsorbent poly(lactic acid), showed excellent swelling properties, demonstrating that cross-linked particles retain their superabsorbent ability, as in their free counterparts, even if distributed in a thermoplastic polymeric matrix. The thermal characteristics of the biocomposites evidence enhanced thermal stability in comparison with neat PLLA and also mechanical properties are markedly modified by addition of crosslinked particles which induce regular stiffening effect. Furthermore, in aqueous environments the particles swell and are leached from PLLA matrix generating very high porosity. These new open-pore PLLA foams, produced in absence of organic solvents and chemical foaming agents, with good physico-mechanical properties appear very promising for several applications, for instance in tissue engineering for scaffold production.

Mechanical Behavior of Tough Hydrogels for Structural Applications

NASA Astrophysics Data System (ADS)

Illeperuma, Widusha Ruwangi Kaushalya

Hydrogels are widely used in many commercial products including Jell-O, contact lenses, and superabsorbent diapers. In recent decades, hydrogels have been under intense development for biomedical applications, such as scaffolds in tissue engineering, carriers for drug delivery, and valves in microfluidic systems. But the scope is severely limited as conventional hydrogels are weak and brittle and are not very stretchable. This thesis investigates the approaches that enhance the mechanical properties of hydrogels and their structural applications. We discov¬ered a class of exceptionally stretchable and tough hydrogels made from poly-mers that form networks via ionic and covalent crosslinks. Although such a hydrogel contains ~90% water, it can be stretched beyond 20 times its initial length, and has a fracture energy of ~9000 J/m2. The combination of large stretchability, remarkable toughness, and recoverability of stiffness and toughness, along with easy synthesis makes this material much superior over existing hydrogels. Extreme stretchability and blunted crack tips of these hydrogels question the validity of traditional fracture testing methods. We re-examine a widely used pure shear test method to measure the fracture energy. With the experimental and simulation results, we conclude that the pure shear test method can be used to measure fracture energy of extremely stretchable materials. Even though polyacrylamide-alginate hydrogels have an extremely high toughness, it has a relatively low stiffness and strength. We improved the stiffness and strength by embedding fibers. Most hydrogels are brittle, allowing the fibers to cut through the hydrogel when the composite is loaded. But tough hydrogel composites do not fail by the fibers cutting the hydrogel; instead, it undergoes large deforming by fibers sliding through the matrix. Hydrogels were not considered as materials for structural applications. But with enhanced mechanical properties, they have opened up novel applications. This thesis aims to investigate the broader applications, well beyond those investigated so far. We show fiber reinforced tough hydrogels can dissipate a significant amount of energy at a tunable level of stress, making them suitable for energy absorbing applications such as inner layer of helmets. We develop inexpensive fire-retarding materials using tough hydrogels that provide superior protection from burn injuries. We also study hydrogels as actuators that can be used in soft robotics. Hydrogels contain mostly water and they freeze when the temperature drops below 00C and lose its functions. We demonstrate a new class of hydrogels that do not freeze and hydrogels that partially freeze below water freezing temperature. Partially freezing hydrogels are ideal for cooling applications such as gel packs and non-freezing hydrogels are useful in all the structural applications at low temperatures. This thesis will enable the use of inexpensive hydrogels in a new class of non-traditional structural applications where the mechanical behavior of the hydrogel is of prime importance.

Foliar antitranspirant and soil superabsorbent hydrogel affects photosynthetic gas exchange and water use efficiency of maize grown under low rainfall conditions.

PubMed

Yang, Wei; Guo, Shi-Wen; Li, Pin-Fang; Song, Ri-Quan; Yu, Jian

2018-06-08

Two lysimeter experiments with maize plants were conducted to inquiry the effect of combined superabsorbent polymer (SAP) and fulvic acid (FA) application on photosynthetic gas exchange and water use efficiency (WUE) under deficit irrigation conditions. Soil SAP (45 kg ha -1 ) was applied while sowing, and FA solution (2 g L -1 ) was sprayed onto crop canopy three times at later plant growth periods. Combining SAP and FA application significantly improved plant photosynthesis, chlorophyll contents, and instantaneous WUE, while maintaining the optimal leaf stomatal transpiration. The effect of combined two chemicals use on photosynthesis and leaf instantaneous WUE was superior compared with the effects of their individual applications. As compared with plots not treated with chemicals, soil SAP significantly improved the yield by 12% and grain WUE by 10% when averaged across the two experiments, whereas foliar FA application did not affect yield and grain WUE. In contrast, the combined use of two chemicals significantly increased the yield by 20% and grain WUE by 26%, largely attributed to the increase in grain number. Soil SAP and foliar FA use, under low rainfall conditions, had little influence on crop water consumption but improved plant WUE by enhancing photosynthesis and increasing kernel number. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Hydrogel Actuation by Electric Field Driven Effects

NASA Astrophysics Data System (ADS)

Morales, Daniel Humphrey

Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of the applied electric field. We extend the use of ionoprinting to develop multi-responsive bilayer gel systems capable of more complex shape transformation. The localized crosslinked regions determine the bending axis as the gel responds to the external environment. The bending can be tuned to reverse direction isothermally by changing the solvent quality or by changing the temperature at a fixed concentration. The multi-responsive behavior is caused by the volume transitions of a non-ionic, thermos-sensitive hydrogel coupled with a superabsorbent ionic hydrogel. Lastly, electric field driven microparticle assembly, using dielectrophoretic (DEP) forces, organized colloidal microparticles within a hydrogel matrix. The use of DEP forces enables rapid, efficient and precise control over the colloidal distribution. The resulting supracolloidal endoskeleton structures impart directional bending as the hydrogel shrinks. We compare the ordered particles structures to random particle distributions in affecting the hydrogel sheet bending response. This study demonstrates a universal technique for imparting directional properties in hydrogels towards new generations of hybrid soft materials.

Multifunctional Environmental Smart Fertilizer Based on l-Aspartic Acid for Sustained Nutrient Release.

PubMed

Lü, Shaoyu; Feng, Chen; Gao, Chunmei; Wang, Xinggang; Xu, Xiubin; Bai, Xiao; Gao, Nannan; Liu, Mingzhu

2016-06-22

Fertilizer is one of the most important elements of modern agriculture. However, conventional fertilizer, when applied to crops, is vulnerable to losses through volatilization, leaching, nitrification, or other means. Such a loss limits crop yields and pollutes the environment. In an effort to enhance nutrient use efficiency and reduce environmental pollution, an environmental smart fertilizer was reported in the current study. Poly(aspartic acid) and a degradable macro-cross-linker based on l-aspartic acid were synthesized and introduced into the fertilizer as a superabsorbent to improve the fertilizer degradability and soil moisture-retention capacity. Sustained release behavior of the fertilizer was achieved in soil. Cumulative release of nitrogen and phosphorus was 79.8% and 64.4% after 30 days, respectively. The water-holding and water-retention capacities of soil with the superabsorbent are obviously higher than those of the control soil without superabsorbent. For the sample of 200 g of soil with 1.5 g of superabsorbent, the water-holding capacity is 81.8%, and the water-retention capacity remains 22.6% after 23 days. All of the current results in this study indicated that the as-prepared fertilizer has a promising application in sustainable modern agriculture.

Evaluation of superabsorbent linseed-polysaccharides as a novel stimuli-responsive oral sustained release drug delivery system.

PubMed

Haseeb, Muhammad Tahir; Hussain, Muhammad Ajaz; Bashir, Sajid; Ashraf, Muhammad Umer; Ahmad, Naveed

2017-03-01

Advancement in technology has transformed the conventional dosage forms to intelligent drug delivery systems. Such systems are helpful for targeted and efficient drug delivery with minimum side effects. Drug release from these systems is governed and controlled by external stimuli (pH, enzymes, ions, glucose, etc.). Polymeric biomaterial having stimuli-responsive properties has opened a new area in drug delivery approach. Potential of a polysaccharide (rhamnogalacturonan)-based hydrogel from Linseeds (Linum usitatissimum L.) was investigated as an intelligent drug delivery material. Different concentrations of Linseed hydrogel (LSH) were used to prepare caffeine and diacerein tablets and further investigated for pH and salt solution-responsive swelling, pH-dependent drug release, and release kinetics. Morphology of tablets was observed using SEM. LSH tablets exhibited dynamic swelling-deswelling behavior with tendency to swell at pH 7.4 and in deionized water while deswell at pH 1.2, in normal saline and ethanol. Consequently, pH controlled release of the drugs was observed from tablets with lower release (<10%) at pH 1.2 and higher release at pH 6.8 and 7.4. SEM showed elongated channels in swollen then freeze-dried tablets. The drug release was greatly influenced by the amount of LSH in the tablets. Drug release from LSH tablets was governed by the non-Fickian diffusion. These finding indicates that LSH holds potential to be developed as sustained release material for tablet.

Respiratory health effects and exposure to superabsorbent polymer and paper dust - an epidemiological study

PubMed Central

2011-01-01

Background The primary aim of the present study was to investigate if exposure to dust from absorbent hygiene products containing superabsorbent polymer is related to symptoms from the airways and from the eyes. The secondary aim was to estimate the current exposure to superabsorbent polymer among production and maintenance workers in a plant producing hygiene products. Methods The cohort comprised 1043 workers of whom 689 were exposed to super absorbent polymer and 804 were exposed to paper dust (overlapping groups). There was 186 workers not exposed to either superabsorbent polymer or to paper dust They were investigated with a comprehensive questionnaire about exposure, asthma, rhinitis and symptoms from eyes and airways. The results were analyzed with logistic regression models adjusting for sex, age, atopy and smoking habits. An aerosol sampler equipped with a polytetrafluoroethylene filter with 1 μm pore size was used for personal samplings in order to measure inhalable dust and superabsorbent polymer. Results The prevalence of nasal crusts (OR 1.4, 95% CI 1.01-2.0) and nose-bleeding (OR 1.7, 95% CI 1.2-2.4) was increased among the paper dust exposed workers (adjusted for superabsorbent polymer exposure). There were no significant effects associated with exposure to superabsorbent polymer (adjusted for paper dust exposure). The average exposure to inhalable levels of total dust (paper dust) varied between 0.40 and 1.37 mg/m3. For superabsorbent polymer dust the average exposure varied between 0.02 and 0.81 mg/m3. Conclusions In conclusion, our study shows that workers manufacturing diapers in the hygiene industry have an increased prevalence of symptoms from the nose, especially nose-bleeding. There was no relation between exposure to superabsorbent polymer and symptoms from eyes, nose or respiratory tract, but exposure to paper dust was associated with nose-bleeding and nasal crusts. This group of workers had also a considerable exposure to superabsorbent polymer dust. PMID:21752269

Coloring a Superabsorbent Polymer with Metal Ions: An Undergraduate Chemistry Experiment

ERIC Educational Resources Information Center

Yaung, Jing-Fun; Chen, Yueh-Huey

2009-01-01

A novel undergraduate chemistry experiment involving superabsorbent polymers commonly used in diapers and other personal care products is described. Students observe the removal of divalent transition-metal ions from aqueous solutions by the polymers. With the procedures provided, students are able to color the superabsorbent polymers with metal…

Cell counting in whole mount tissue volumes using expansion OCT (Conference Presentation)

NASA Astrophysics Data System (ADS)

Liu, Yehe; Gu, Shi; Watanabe, Michiko; Rollins, Andrew M.; Jenkins, Michael W.

2017-02-01

Abnormal cell proliferation and migration during heart development can lead to severe congenital heart defects (CHDs). Studying the spatial distribution of cells during embryonic development helps our understanding of how the heart develops and the etiology of certain CHDs. However, imaging large groups of single cells in intact tissue volumes is challenging. No current technique can accomplish this task in both a time-efficient and cost-effective manner. OCT has potential with its large field of view and micron-scale resolution, but even the highest resolution OCT systems have poor contrast for counting cells and have a small field of view compared to conventional OCT. We propose using a conventional OCT system and processing the sample to enhance cellular contrast. Inspired by the recently developed Expansion Microscopy, we permeated whole-mount embryonic tissue with a superabsorbent monomer solution and polymerized into a hydrogel. When hydrated in DI water, the tissue-hydrogel complex was uniformly enlarged ( 5X in all dimensions) without distorting the microscopic structure. This had a twofold effect: it increased the resolution by a factor of 5 and decreased scattering, which allowed us to resolve cellular level features deep in the tissue with high contrast using conventional OCT. We noted that cell nuclei caused significantly more backscattering than the other subcellular structures after expansion. Based on this property, we were able to distinguish individual cell nuclei, and thus count cells, in expanded OCT images with simple intensity thresholding. We demonstrate the technique with embryonic quail hearts at various developmental stages.

"JCE" Classroom Activity #106. Sequestration of Divalent Metal Ion by Superabsorbent Polymer in Diapers

ERIC Educational Resources Information Center

Chen, Yueh-Huey; Lin, Jia-Ying; Lin, Li-Pin; Liang, Han; Yaung, Jing-Fun

2010-01-01

This activity explores an alternative use of a superabsorbent polymer known as a water absorbing material. A dilute solution of CuCl[subscript 2] is treated with a small piece of unused disposable diaper containing superabsorbent sodium polyacrylates. The polymer is used for the removal of Cu[superscript 2+] ions from the solution. The…

Measurement of respirable superabsorbent polyacrylate (SAP) dust by ethanol derivatization using gas chromatography-mass spectrometry (GC-MS) detection.

PubMed

McCormack, Paul; Lemmo, John S; Macomber, Margaret; Holcomb, Mark L; Lieckfield, Robert

2011-04-01

Superabsorbent polyacrylate (SAP) is an important industrial chemical manufactured primarily as sodium polyacrylate but occasionally as potassium salt. It has many applications owing to its intrinsic physical property of very high water absorption, which can be more than 100 times it own weight. SAP is commonly used in disposable diapers and feminine hygiene products and is known by a number of synonyms-sodium polyacrylate, superabsorbent polyacrylate (SAP), polyacrylate absorbent (PA), and superabsorbent material (SAM). Germany and The Netherlands have adopted a nonbinding scientific guideline value 0.05 mg/m³ (8-hr time-weighted average, TWA) as the maximum allowable workplace concentration for the respirable dust of SAP (<10 μm particle diameter). Three industry associations representing Europe, the United States, and Asia have adopted the German scientific guideline value of 0.05 mg/m³ (8-hr TWA) as a voluntary guideline. A new test method based on alcohol derivatization of the acrylate was developed and validated for the analysis of respirable superabsorbent polyacrylate dust collected on filter cassettes in the workplace environment. This method is an alternative to the commonly used sodium-based method, which is limited owing to potential interference by other sources of sodium from the workplace and laboratory environments. The alcohol derivatization method effectively eliminates sodium interference from several classes of sodium compounds, as shown by their purposeful introduction at two and six times the equivalent amount of SAP present in reference samples. The accuracy of the method, as determined by comparison with sodium analysis of known reference samples, was greater than 80% over the study range of 5-50 μg of SAP dust. The lower reporting limit of the method is 3.0 μg of SAP per sample, which is equivalent to 3 (μg/m³) for an 8-hr sampling period at the recommended flow rate of 2.2 L/min.

Preparation of a low-cost and eco-friendly superabsorbent composite based on wheat bran and laterite for potential application in Chinese herbal medicine growth.

PubMed

Gao, Jiande; Liu, Jin; Peng, Hui; Wang, Yaya; Cheng, Sha; Lei, Ziqiang

2018-05-01

A low-cost and eco-friendly superabsorbent composite is prepared through the free-radical graft co-polymerization of wheat bran (WB), acrylic acid (AA) and laterite (LA) in an aqueous solution. Elemental map, scanning electron microscopy and Fourier transform infrared spectra revealed that the LA evenly distributed in the superabsorbent composite and wheat bran-g-poly(acrylic acid)/laterite (WB-g-PAA/LA) formed successfully. Thermogravimetric analysis confirmed that the WB-g-PAA/LA had high thermal stability. Furthermore, the properties of the WB-g-PAA/LA, such as swelling in saline solutions and degradation, are also assessed. The final WB-g-PAA/LA (5 wt%) superabsorbent composite attained an optimum water absorbency of 1425 g g -1 in distilled water and 72 g g -1 in 0.9 wt% NaCl solution. The water absorbency of WB-g-PAA/LA (10 wt%) is even greater than that of the WB-g-PAA. Moreover, the water-retention capacity of WB-g-PAA/LA (5 wt%) is high, and the water-retention process followed a zero-order reaction. The reaction rate constant is 8.2428 × 10 5 exp(- E a /RT ) and the apparent activation energy ( E a ) is 35.11 kJ mol -1 . Furthermore, WB-g-PAA/LA (5 wt%) may regulate the release of urea, indicating that the superabsorbent composite could provide a promising application as a urea fertilizer carrier. Additionally, it increased the germination and growth rates of Glycyrrhiza uralensis Fisch, suggesting it could influence the growth of Chinese herbal medicine.

Preparation of a low-cost and eco-friendly superabsorbent composite based on wheat bran and laterite for potential application in Chinese herbal medicine growth

PubMed Central

Liu, Jin; Peng, Hui; Wang, Yaya; Cheng, Sha; Lei, Ziqiang

2018-01-01

A low-cost and eco-friendly superabsorbent composite is prepared through the free-radical graft co-polymerization of wheat bran (WB), acrylic acid (AA) and laterite (LA) in an aqueous solution. Elemental map, scanning electron microscopy and Fourier transform infrared spectra revealed that the LA evenly distributed in the superabsorbent composite and wheat bran-g-poly(acrylic acid)/laterite (WB-g-PAA/LA) formed successfully. Thermogravimetric analysis confirmed that the WB-g-PAA/LA had high thermal stability. Furthermore, the properties of the WB-g-PAA/LA, such as swelling in saline solutions and degradation, are also assessed. The final WB-g-PAA/LA (5 wt%) superabsorbent composite attained an optimum water absorbency of 1425 g g−1 in distilled water and 72 g g−1 in 0.9 wt% NaCl solution. The water absorbency of WB-g-PAA/LA (10 wt%) is even greater than that of the WB-g-PAA. Moreover, the water-retention capacity of WB-g-PAA/LA (5 wt%) is high, and the water-retention process followed a zero-order reaction. The reaction rate constant is 8.2428 × 105 exp(−Ea/RT) and the apparent activation energy (Ea) is 35.11 kJ mol−1. Furthermore, WB-g-PAA/LA (5 wt%) may regulate the release of urea, indicating that the superabsorbent composite could provide a promising application as a urea fertilizer carrier. Additionally, it increased the germination and growth rates of Glycyrrhiza uralensis Fisch, suggesting it could influence the growth of Chinese herbal medicine. PMID:29892438

Crack Mitigation in Concrete: Superabsorbent Polymers as Key to Success?

PubMed Central

Mignon, Arn; Snoeck, Didier; Dubruel, Peter; Van Vlierberghe, Sandra; De Belie, Nele

2017-01-01

Cracking is a major concern in building applications. Cracks may arise from shrinkage, freeze/thawing and/or structural stresses, amongst others. Several solutions can be found but superabsorbent polymers (SAPs) seem to be interesting to counteract these problems. At an early age, the absorbed water by the SAPs may be used to mitigate autogenous and plastic shrinkage. The formed macro pores may increase the freeze/thaw resistance. The swelling upon water ingress may seal a crack from intruding fluids and may regain the overall water-tightness. The latter water may promote autogenous healing. The use of superabsorbent polymers is thus very interesting. This review paper summarizes the current research and gives a critical note towards the use of superabsorbent polymers in cementitious materials. PMID:28772599

Crack Mitigation in Concrete: Superabsorbent Polymers as Key to Success?

PubMed

Mignon, Arn; Snoeck, Didier; Dubruel, Peter; Van Vlierberghe, Sandra; De Belie, Nele

2017-02-28

Cracking is a major concern in building applications. Cracks may arise from shrinkage, freeze/thawing and/or structural stresses, amongst others. Several solutions can be found but superabsorbent polymers (SAPs) seem to be interesting to counteract these problems. At an early age, the absorbed water by the SAPs may be used to mitigate autogenous and plastic shrinkage. The formed macro pores may increase the freeze/thaw resistance. The swelling upon water ingress may seal a crack from intruding fluids and may regain the overall water-tightness. The latter water may promote autogenous healing. The use of superabsorbent polymers is thus very interesting. This review paper summarizes the current research and gives a critical note towards the use of superabsorbent polymers in cementitious materials.

New protocol for synthesis of new nanomaterials with continuous 3D networks

NASA Astrophysics Data System (ADS)

Wang, Haiwang; Zhu, Ying; Wei, Xinfang; Chen, Huanhuan; Wang, Ruijie; Zhang, Dong; Song, Huaihe; Song, Shengju

2014-05-01

Nanostructured materials are attractive to researchers because of their unique optical, magnetic, thermodynamic, electrical, mechanical, and chemical properties. Controlling the morphology of nanomaterials could provide structural systems for a wide range of technologies. As a result, the development of nanofabrication techniques that are convenient and offer design flexibility is the subject of many studies. In order to progress beyond the conventional morphologies, we have turned to hydrogels, which can serve as organic templates for nanoscale objects with continuous microstructures. Transmission electron microscopy showed that the obtained nanonetwork had a continuous microstructure, which was several microns in length and width, with a cross-sectional diameter of 5-10 nm synthesized from a 35-g hexamethylenetetramine solution and a 1.5 g Zn(NO3)2 solution, and the cross-sectional diameter can be adjusted from 5 to 200 nm by controlling the concentration of the Zn(NO3)2 solution. Our results also showed that the nanostructures based on a superabsorbent polymer template could be controlled easily in terms of size and morphology by changing the concentration of the reaction solution. This protocol could be easily extended to synthesize a variety of nanostructured materials with novel morphologies.

Novel hydrogel-based preparation-free EEG electrode.

PubMed

Alba, Nicolas Alexander; Sclabassi, Robert J; Sun, Mingui; Cui, Xinyan Tracy

2010-08-01

The largest obstacles to signal transduction for electroencephalography (EEG) recording are the hair and the epidermal stratum corneum of the skin. In typical clinical situations, hair is parted or removed, and the stratum corneum is either abraded or punctured using invasive penetration devices. These steps increase preparation time, discomfort, and the risk of infection. Cross-linked sodium polyacrylate gel swelled with electrolyte was explored as a possible skin contact element for a prototype preparation-free EEG electrode. As a superabsorbent hydrogel, polyacrylate can swell with electrolyte solution to a degree far beyond typical contemporary electrode materials, delivering a strong hydrating effect to the skin surface. This hydrating power allows the material to increase the effective skin contact surface area through wetting, and noninvasively decrease or bypass the highly resistive barrier of the stratum corneum, allowing for reduced impedance and improved electrode performance. For the purposes of the tests performed in this study, the polyacrylate was prepared both as a solid elastic gel and as a flowable paste designed to penetrate dense scalp hair. The gel can hold 99.2% DI water or 91% electrolyte solution, and the water content remains high after 29 h of air exposure. The electrical impedance of the gel electrode on unprepared human forearm is significantly lower than a number of commercial ECG and EEG electrodes. This low impedance was maintained for at least 8 h (the longest time period measured). When a paste form of the electrode was applied directly onto scalp hair, the impedance was found to be lower than that measured with commercially available EEG paste applied in the same manner. Time-frequency transformation analysis of frontal lobe EEG recordings indicated comparable frequency response between the polyacrylate-based electrode on unprepared skin and the commercial EEG electrode on abraded skin. Evoked potential recordings demonstrated signal-to-noise ratios of the experimental and commercial electrodes to be effectively equivalent. These results suggest that the polyacrylate-based electrode offers a powerful option for EEG recording without scalp preparation.

Effects of alternate drip irrigation and superabsorbent polymers on growth and water use of young coffee tree.

PubMed

Liu, Xiaogang; Li, Fusheng; Yang, Qiliang; Wang, Xinle

2016-07-01

To obtain optimal irrigation management for young coffee tree, the effects of alternate drip irrigation (ADI) and superabsorbent polymers on physiology, growth, dry mass accumulation and water use on one-year old Coffea arabica L. tree were investigated. This experiment had three drip irrigation methods, i.e., conventional drip irrigation (CDI), alternate drip irrigation (ADI) and fixed drip irrigation (FDI), and two levels of superabsorbent polymers, i.e., no superabsorbent polymers (NSAP) and added superabsorbent polymers (SAP). Compared to CDI, ADI saved irrigation water by 32.1% and increased water use efficiency (WUE) by 29.9%. SAP increased root-shoot ratio, total dry mass and WUE by 20.3, 24.9 and 33.0%, respectively, when compared to NSAP. Compared to CDI with NSAP treatment, ADI with SAP treatment increased total dry mass by 13.8% and saved irrigation water by 34.4%, thus increased WUE by 73.4%, and it increased root activity, the contents of chlorophyll and soluble sugar in leaves by 162.4, 38.0 and 8.5%, but reduced the contents of proline and malondialdehyde in leaves by 7.2 and 9.7%, respectively. Thus, alternate drip irrigation with superabsorbent polymers increased the growth and WUE of young Coffea arabica L. tree and was optimal irrigation management for young coffee tree.

Plant Growth Research for Food Production: Development and Testing of Expandable Tuber Growth Module

NASA Technical Reports Server (NTRS)

Cordova, Brennan A.

2017-01-01

Controlled and reliable growth of a variety of vegetable crops is an important capability for manned deep space exploration systems for providing nutritional supplementation and psychological benefits to crew members. Because current systems have been limited to leafy vegetables that require minimal root space, a major goal for these systems is to increase their ability to grow new types of crops, including tuber plants and root vegetables that require a large root space. An expandable root zone module and housing was developed to integrate this capability into the Vegetable Production System (Veggie). The expandable module uses a waterproof, gas-permeable bag with a structure that allows for root space to increase vertically throughout the growth cycle to accommodate for expanding tuber growth, while minimizing the required media mass. Daikon radishes were chosen as an ideal tuber crop for their subterraneous tuber size and rapid growth cycle, and investigations were done to study expanding superabsorbent hydrogels as a potential growth media. These studies showed improved water retention, but restricted oxygen availability to roots with pure gel media. It was determined that these hydrogels could be integrated in lower proportions into standard soil to achieve media expansion and water retention desired. Using the constructed module prototype and ideal gel and soil media mixture, daikon radishes are being grown in the system to test the capability and success of the system through a full growth cycle.

Plant Growth Research for Food Production: Development and Testing of Expandable Tuber Growth Module

NASA Technical Reports Server (NTRS)

Cordova, Brennan A.

2017-01-01

Controlled and reliable growth of a variety of vegetable crops is an important capability for manned deep space exploration systems for providing nutritional supplementation and psychological benefits to crew members. Because current systems have been limited to leafy vegetables that require minimal root space, a major goal for these systems is to increase their ability to grow new types of crops, including tuber plants and root vegetables that require a large root space. An expandable root zone module and housing was developed to integrate this capability into the Veggie growth system. The expandable module uses a waterproof, gas-permeable bag with a structure that allows for root space to increase vertically throughout the growth cycle to accommodate for expanding tuber growth, while minimizing the required media mass. Daikon radishes were chosen as an ideal tuber crop for their subterraneous tuber size and rapid growth cycle, and investigations were done to study expanding superabsorbent hydrogels as a potential growth media. These studies showed improved water retention, but restricted oxygen availability to roots with pure gel media. It was determined that these hydrogels could be integrated in lower proportions into standard soil to achieve media expansion and water retention desired. Using the constructed module prototype and ideal gel and soil media mixture, Daikon radishes were grown in the system to test the capability and success of the system through a full growth cycle.

Characteristics and mechanisms of acrylate polymer damage to maize seedlings.

PubMed

Chen, Xian; Mao, Xiaoyun; Lu, Qin; Liao, Zongwen; He, Zhenli

2016-07-01

Superabsorbent acrylate polymers (SAPs) have been widely used to maintain soil moisture in agricultural management, but they may cause damage to plants, and the mechanisms are not well understood. In this study, seed germination, soil pot culture, hydroponic experiments, and SAPs degradation were conducted to investigate damage characteristics and mechanisms associated with SAPs application. The Results showed that SAPs inhibited maize growth and altered root morphology (irregular and loose arrangement of cells and breakage of cortex parenchyma), and the inhibitory effects were enhanced at higher SAPs rates. After 1h SAP hydrogels treatment, root malondialdehyde (MDA) content was significantly increased, while superoxide dismutase (SOD) and catalase (CAT) content were significantly decreased. Hydroponics experiment indicated that root and shoot growth was inhibited at 2.5mgL(-1) acrylic acid (AA), and the inhibition was enhanced with increasing AA rates. This effect was exacerbated by the presence of Na(+) at a high concentration in the hydrogels. Release and degradation of AA were enhanced at higher soil moisture levels. A complete degradation of AA occurred between 15 and 20 days after incubation (DAI), but it took longer for Na(+) concentration to decrease to a safe level. These results indicate that high concentration of both AA and Na(+) present in the SAPs inhibits plant growth. The finding of this study may provide a guideline for appropriate application of SAPs in agriculture. Copyright © 2016 Elsevier Inc. All rights reserved.

Sugarcane bagasse derivative-based superabsorbent containing phosphate rock with water-fertilizer integration.

PubMed

Zhong, Kang; Zheng, Xi-Liang; Mao, Xiao-Yun; Lin, Zuan-Tao; Jiang, Gang-Biao

2012-10-01

To improve the water-fertilizer utilization ratio and mitigate the environmental contamination, an eco-friendly superabsorbent polymer (SPA), modified sugarcane bagasse/poly (acrylic acid) embedding phosphate rock (MSB/PAA/PHR), was prepared. Ammonia, phosphate rock (PHR) and KOH were admixed in the presence of acrylic acid to provide nitrogen (N), phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent polymer (SAP) were investigated. The maximum swelling capacity in distilled water and 0.9 wt.% (weight percent) NaCl solution reached 414 gg(-1) and 55 gg(-1) (water/prepared SAP), respectively. The available NPK contents of the combination system were 15.13 mgg(-1), 6.93 mgg(-1) and 52.05 mgg(-1), respectively. Moreover, the release behaviors of NPK in the MSB/PAA/PHR were also studied. The results showed that the MSB/PAA/PHR has outstanding sustained-release plant nutrients property. Copyright © 2012 Elsevier Ltd. All rights reserved.

Accurate determination of residual acrylic acid in superabsorbent polymer of hygiene products by headspace gas chromatography.

PubMed

Zhang, Shu-Xin; Chai, Xin-Sheng; Jiang, Ran

2017-02-17

This work reports on a method for the determination of residual acrylic acid (AA) in the superabsorbent polymers for hygiene products by headspace analysis. It was based on water extraction for the polymer sample at a room temperature for 50min. Then, the AA in the extractant reacted with bicarbonate solution in a closed headspace sample vial, from which the carbon dioxide generated from the reaction (within 20min at 70°C) was detected by gas chromatography (GC). It was found that there is adsorption partition equilibrium of AA between solid-liquid phases. Therefore, an equation for calculating the total AA content in the original polymers sample was derived based on the above phase equilibrium. The results show that the HS-GC method has good precision (RSD<2.51%) and good accuracy (recoveries from 93 to 105%); the limit of quantification (LOQ) was 373mg/kg. The present method is rapid, accurate, and suitable for determining total residual acrylic acid in a wide variety of applications from processing of superabsorbent polymer to commercial products quality control. Copyright © 2017 Elsevier B.V. All rights reserved.

Relevance of nonfunctional linear polyacrylic acid for the biodegradation of superabsorbent polymer in soils.

PubMed

Bai, Mo; Wilske, Burkhard; Buegger, Franz; Esperschütz, Jürgen; Bach, Martin; Frede, Hans-Georg; Breuer, Lutz

2015-04-01

Biodegradability is a desired characteristic for synthetic soil amendments. Cross-linked polyacrylic acid (PAA) is a synthetic superabsorbent used to increase the water availability for plant growth in soils. About 4% within products of cross-linked PAA remains as linear polyacrylic acid (PAAlinear). PAAlinear has no superabsorbent function but may contribute to the apparent biodegradation of the overall product. This is the first study that shows specifically the biodegradation of PAAlinear in agricultural soil. Two (13)C-labeled PAAlinear of the average molecular weights of 530, 400, and 219,500 g mol(-1) were incubated in soil. Mineralization of PAAlinear was measured directly as the (13)CO2 efflux from incubation vessels using an automatic system, which is based on (13)C-sensitive wavelength-scanned cavity ring-down spectroscopy. After 149 days, the PAAlinear with the larger average molecular weight and chain length showed about half of the degradation (0.91% of the initial weight) of the smaller PAAlinear (1.85%). The difference in biodegradation was confirmed by the δ(13)C signature of the microbial biomass (δ(13)Cmic), which was significantly enriched in the samples with short PAAlinear (-13‰ against reference Vienna Pee Dee Belemnite,VPDB) as compared to those with long PAAlinear (-16‰ VPDB). In agreement with other polymer studies, the results suggest that the biodegradation of PAAlinear in soil is determined by the average molecular weight and occurs mainly at terminal sites. Most importantly, the study outlines that the size of PAA that escapes cross-linking can have a significant impact on the overall biodegradability of a PAA-based superabsorbent.

Nanotechnology in Science and Art

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bearinger, J

2007-02-21

The burgeoning field of nanotechnology opens windows between science and art. Exploration of this interplay encourages interaction between scientists, artists and educators alike. The image below serves as an example of the fertile ground for exchange. The substrate that this image captures is made of silicon, the material from which computer chips are made. A thin ({approx}1 nm thick) chemical coating was applied homogeneously to the silicon. Specific regions of the coating, 600 nm wide (approximately 150 times smaller than the diameter of a human hair), were then locally removed from the silicon via photocatalytic nanolithography (PCNL(Bearinger, Hiddessen et al.more » 2005)). PCNL engages light, such as from a light emitting diode or an ultraviolet source, to activate molecules that are attached to a transparent mask above the silicon substrate. These molecules can be compounds similar to chlorophyll, the photoactive material that aids plants in photosynthesis, or may be semiconductor materials, such as TiO{sub 2}. Once these molecules are activated, chemical reactions result in local destruction of the coating on the silicon. Thus, only regions of the coated silicon in close contact with mask are affected. A non-fouling polymer hydrogel ({approx}10 nm thick) was then grafted to the retained coating. Hydrogels are superabsorbent and are therefore used on the bulk scale in common items including contact lenses and diapers. They also find utility in topical drug delivery and tissue engineering applications. Because the hydrogel is so absorbent, exposing the silicon chip with patterned hydrogel to water vapor from one's breath reveals the pattern that the lithography dictates(Lopez, Biebuyck et al. 1993). The myriad of colors seen in the image are due to optical interference. The thickness of the swollen layer determines the colors that are visible. While the field of view immediately following hydration appears like a big drop of oil shining in the sun, the oil drop appearance breaks up into many small domains as the water vapor evaporates. The base silicon does not retain the water in the same way that the way the hydrogel does, due to differences in surface tension. Thus, the pattern stands out from the background. In addition to bringing together nanotechnology, polymer chemistry, materials science and optics, this image suggests imposing order to an otherwise chaotic world. This is a repeated theme in nature across multiple orders of magnitude. The interface of this order and chaos is amorphous, and render a Klimt-like vision of reflected light. As this image is just a still in time, it also reminds us that all things and states are transient and that the materials of the earth, just as we individuals, are constantly evolving.« less

Validation of a new menstrual pictogram (superabsorbent polymer-c version) for use with ultraslim towels that contain superabsorbent polymers.

PubMed

Magnay, Julia L; Nevatte, Tracy M; O'Brien, Shaughn; Gerlinger, Christoph; Seitz, Christian

2014-02-01

To validate the menstrual pictogram (superabsorbent polymer-c version) for Always Ultra-slim feminine towels containing superabsorbent polymers. Prospective, multicenter, evaluator-blinded study. Three gynecology research clinics in the United Kingdom. Women with self-perceived light, normal, or heavy menstrual periods who had not previously used a graphical method to assess their menstrual loss. One hundred twenty-two women were asked to complete the menstrual pictogram throughout two menstrual periods and collect their feminine towels for measurements of menstrual blood loss (MBL) by the alkaline hematin method and total menstrual fluid loss (MFL) by fluid weight. Agreement of menstrual pictogram MBL and MFL scores with alkaline hematin and towel weight, respectively. The percentage blood fraction was determined at various volumes of menstrual discharge. Alkaline hematin and fluid weight were highly correlated (r = .97). However, the percentage blood fraction progressively increased with total MFL and MBL score. After correction for this incremental rise in blood fraction, the menstrual pictogram gave a sensitivity of 82% and a specificity of 92% for a diagnosis of heavy menstrual bleeding. The menstrual pictogram (superabsorbent polymer-c version) provides a simple means of measuring MBL in the clinical setting. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Modification of wheat gluten with citric acid to produce superabsorbent materials

USDA-ARS?s Scientific Manuscript database

Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra-red (FTIR) spectroscopy, thermogravimetric analysis, and water uptak...

Smart swelling biopolymer microparticles by a microfluidic approach: synthesis, in situ encapsulation and controlled release.

PubMed

Fang, Aiping; Cathala, Bernard

2011-01-01

This paper reports a microfluidic synthesis of biopolymer microparticles aiming at smart swelling. Monodisperse aqueous emulsion droplets comprising biopolymer and its cross-linking agent were formed in mineral oil and solidified in the winding microfluidic channels by in situ chaotic mixing, which resulted in internal chemical gelation for hydrogels. The achievement of pectin microparticles from in situ mixing pectin with its cross-linking agent, calcium ions, successfully demonstrates the reliability of this microfluidic synthesis approach. In order to achieve hydrogels with smart swelling, the following parameters and their impacts on the swelling behaviour, stability and morphology of microparticles were investigated: (1) the type of biopolymers (alginate or mixture of alginate and carboxymethylcellulose, A-CMC); (2) rapid mixing; (3) concentration and type of cross-linking agent. Superabsorbent microparticles were obtained from A-CMC mixture by using ferric chloride as an additional external cross-linking agent. The in situ encapsulation of a model protein, bovine serum albumin (BSA), was also carried out. As a potential protein drug-delivery system, the BSA release behaviours of the biopolymer particles were studied in simulated gastric and intestinal fluids. Compared with alginate and A-CMC microparticles cross-linked with calcium ions, A-CMC microparticles cross-linked with both calcium and ferric ions demonstrate a significantly delayed release. The controllable release profile, the facile encapsulation as well as their biocompatibility, biodegradability, mucoadhesiveness render this microfluidic approach promising in achieving biopolymer microparticles as protein drug carrier for site-specific release. Copyright © 2010 Elsevier B.V. All rights reserved.

Application of encapsulated superabsorbent polymers in cementitious materials for stimulated autogenous healing

NASA Astrophysics Data System (ADS)

Pelto, Jani; Leivo, Markku; Gruyaert, Elke; Debbaut, Brenda; Snoeck, Didier; De Belie, Nele

2017-10-01

Superabsorbent polymers have shown potential for use in mortar and concrete as self-healing agents. The main drawback is, however, that these superabsorbent polymers also absorb mixing water during the preparation and casting of mortar or concrete, leading to a loss in workability. To avoid the absorption of mixing water, superabsorbent polymers were coated using a fluid bed spraying process. The barrier coating consisted of three successive coating layers: polyvinylbutyral as primer/wetting layer, cyclo-olefin copolymer as a barrier layer and a sol-gel derived zirconium-silicon oxide as an adhesion-promoting topcoat layer. The coated SAPs were characterized, and their swelling determined to quantify the delay in uptake of water and Ca(OH)2 solution. The last was considered as the most important, as the SAPs will finally be applied in mortar or concrete having a pore solution with high pH. The results showed that swelling could be delayed to a large extent, but for a short time. Results showed that the self-sealing efficiency of mortars was not affected by coating the SAPs. Moreover, due to the reduced uptake of mixing water, the strength reduction, noticed when uncoated SAPs were added to the mortar, could partly be compensated.

Superabsorbent Multilayer Fabric

NASA Technical Reports Server (NTRS)

Coreale, J. V.; Dawn, F. S.

1982-01-01

Material contains gel-forming polymer and copolymer that absorb from 70 to 200 times their weight of liquid. Superabsorbent Polymer and Copolymer form gels to bind and retain liquid in multiply fabric. Until reaction between liquid and absorbent masses forms gel, backing layer retains liquids within fabric; also allows material to "breathe." Possible applications include baby diapers, female hygiene napkins, and hospital bedpads. Might also have uses in improvement of dry soil.

Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize.

PubMed

Tao, Jinghe; Zhang, Wenxu; Liang, Li; Lei, Ziqiang

2018-02-01

Desertification is the degradation of land in arid and semi-arid areas. Nowadays, lack of water and desertification are extreme problems for plant survival and growth in the arid and semi-arid areas of the world. It becomes increasingly important as to how to let the plant absorb moisture more effectively for keeping growth strong. We synthesized superabsorbent polymers (SAPs) with carbohydrate and characterized them by Fourier transform infrared spectra analyses, scanning electron microscopy and thermogravimetric/differential thermal analyses. Then, a completely randomized experiment was conducted to assess the effect of carbohydrate-based SAPs on seed germination and seedling growth of maize in an artificial climate chest. The results showed that adding an appropriate amount of SAPs could improve root length, shoot length, total biomass, germination potential and germination rate. It indicates that this SAP is not toxic to plants and can promote seed germination, and at the same time provides a possibility of replacing other substrates.

Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize

NASA Astrophysics Data System (ADS)

Tao, Jinghe; Zhang, Wenxu; Liang, Li; Lei, Ziqiang

2018-02-01

Desertification is the degradation of land in arid and semi-arid areas. Nowadays, lack of water and desertification are extreme problems for plant survival and growth in the arid and semi-arid areas of the world. It becomes increasingly important as to how to let the plant absorb moisture more effectively for keeping growth strong. We synthesized superabsorbent polymers (SAPs) with carbohydrate and characterized them by Fourier transform infrared spectra analyses, scanning electron microscopy and thermogravimetric/differential thermal analyses. Then, a completely randomized experiment was conducted to assess the effect of carbohydrate-based SAPs on seed germination and seedling growth of maize in an artificial climate chest. The results showed that adding an appropriate amount of SAPs could improve root length, shoot length, total biomass, germination potential and germination rate. It indicates that this SAP is not toxic to plants and can promote seed germination, and at the same time provides a possibility of replacing other substrates.

Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize

PubMed Central

Tao, Jinghe; Liang, Li; Lei, Ziqiang

2018-01-01

Desertification is the degradation of land in arid and semi-arid areas. Nowadays, lack of water and desertification are extreme problems for plant survival and growth in the arid and semi-arid areas of the world. It becomes increasingly important as to how to let the plant absorb moisture more effectively for keeping growth strong. We synthesized superabsorbent polymers (SAPs) with carbohydrate and characterized them by Fourier transform infrared spectra analyses, scanning electron microscopy and thermogravimetric/differential thermal analyses. Then, a completely randomized experiment was conducted to assess the effect of carbohydrate-based SAPs on seed germination and seedling growth of maize in an artificial climate chest. The results showed that adding an appropriate amount of SAPs could improve root length, shoot length, total biomass, germination potential and germination rate. It indicates that this SAP is not toxic to plants and can promote seed germination, and at the same time provides a possibility of replacing other substrates. PMID:29515838

The water kinetics of superabsorbent polymers during cement hydration and internal curing visualized and studied by NMR.

PubMed

Snoeck, D; Pel, L; De Belie, N

2017-08-25

SuperAbsorbent Polymers (SAPs) can be applied as an admixture in cementitious materials. As the polymers are able to swell, they will absorb part of the mixing water and can then release that water back towards the cementitious matrix for internal curing. This is interesting in terms of autogenous shrinkage mitigation as the internal relative humidity is maintained. The mechanism is theoretically described by the Powers and Brownyard model, but the kinetics and water release still remain subject of detailed investigation. This paper uses Nuclear Magnetic Resonance (NMR) to study the release of water from the superabsorbent polymers towards the cementitious matrix during cement hydration. The release of water by the SAPs is monitored as a function of time and degree of hydration. The internal humidity is also monitored in time by means of sensitive relative-humidity sensors.

Electrochemical immunoassay for tumor markers based on hydrogels.

PubMed

Yin, Shuang; Ma, Zhanfang

2018-05-08

Hydrogel-based electrochemical immunoassays exhibit a large surface-to-volume ratio, excellent biocompatibility, unique stimuli-responsive behavior, high permeability and hydrophilicity and, thus, have shown great potential in the sensitive and accurate detection of tumor markers. Electrochemical immunosensing techniques for tumor markers based on hydrogels have greatly progressed in recent years. Areas covered: In this review, the authors describe the recent advances of hydrogel-based electrochemical immunosensing interface of tumor markers based on the different functions of hydrogels including conductive, catalytic, redox, stimuli-responsive and antifouling hydrogels. Expert commentary: Hydrogels have been successfully employed in electrochemical immunoassay of tumor markers, which is accountable to their unique properties. For further exploitation of hydrogel-based electrochemical biosensors, more variety of hydrogels need be fabricated with improved functionality.

Two Year Old With Water Bead Ingestion.

PubMed

Jackson, Jami; Randell, Kimberly A; Knapp, Jane F

2015-08-01

Foreign body ingestion is a common pediatric complaint. Two case reports describe intestinal obstruction in children from an ingestion of a single superabsorbent water ball, requiring surgical removal. We describe nonsurgical management of an asymptomatic child who ingested approximately 100 superabsorbent water beads.Because of the risk for subsequent intestinal obstruction, the patient was admitted for whole bowel irrigation. This case report is the first describing use of whole bowel irrigation in the management of an asymptomatic patient with multiple water beads ingestion.

Synthesis and evaluation of a superabsorbent-fertilizer composite for maximizing the nutrient and water use efficiency in forestry plantations.

PubMed

Tubert, E; Vitali, V A; Alvarez, M S; Tubert, F A; Baroli, I; Amodeo, G

2018-03-15

Reducing fertilizer use is a priority in the quest for sustainable forestry systems. In short rotation Eucalyptus plantations, NPK pellets are routinely added to the seedling's top soil layer at planting, potentially leading to increased seedling mortality, nutrient loss and environmental degradation. To address this triple challenge, the development of efficient fertilization practices is essential. In the present work, we synthesized a crosslinked acrylic-cellulosic superabsorbent composite (SAPH-BAL) containing small amounts of specific nutrients integrated in the polymer matrix. We analyzed the composite's chemical and rheological properties, and assessed the viability of Eucalyptus plantations supplied with it at planting. Physiological measurements confirmed the suitability of SAPH-BAL in greenhouse-grown potted seedlings subjected to different growth conditions, showing that it efficiently delivers nutrients while protecting seedlings from drought stress. Field experiments carried out at ten South American locations covering an ample range of environmental conditions confirmed the beneficial effect of SAPH-BAL on growth and survival in comparison to the conventional fertilization scheme (superabsorbent + 75 g NPK). Furthermore, it was found that plants treated with SAPH-BAL were less affected by the differences in rainfall regimes during the experiments compared to those fertilized conventionally. To the best of our knowledge this is the first report describing the successful use of superabsorbents for root targeted delivery of fertilizers in forestry operations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sorption kinetics of superabsorbent polymers (SAPs) in fresh Portland cement-based pastes visualized and quantified by neutron radiography and correlated to the progress of cement hydration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroefl, Christof, E-mail: christof.schroefl@tu-dresden.de; Mechtcherine, Viktor; Vontobel, Peter

2015-09-15

Water sorption of two superabsorbent polymers in cement-based pastes has been characterized by neutron radiography. Cement pastes with W/C of 0.25 and 0.50 and one additionally containing silica fume (W/C = 0.42) were investigated. The SAPs differed in their inherent sorption kinetics in extracted cement pore solution (SAP 1: self-releasing; SAP 2: retentive). Desorption from SAP 1 started very early after paste preparation. Hence, its individual non-retentiveness governs its behavior only. SAP 2 released water into all matrices, but its kinetics were different. In the paste with the highest W/C, some moderate water release was recorded from the beginning. Inmore » the other two pastes, SAP 2 retained its stored liquid during the dormant period, i.e., up to the percolation threshold. Intense desorption then set in and continued throughout the acceleration period. These findings explain the pronouncedly higher efficiency of SAP 2 as internal curing admixture as compared to SAP 1.« less

Functional nucleic acid-based hydrogels for bioanalytical and biomedical applications

PubMed Central

Mo, Liuting; Lu, Chun-Hua; Fu, Ting

2016-01-01

Hydrogels are crosslinked hydrophilic polymers that can absorb a large amount of water. By their hydrophilic, biocompatible and highly tunable nature, hydrogels can be tailored for applications in bioanalysis and biomedicine. Of particular interest are DNA-based hydrogels owing to the unique features of nucleic acids. Since the discovery of DNA double helical structure, interest in DNA has expanded beyond its genetic role to applications in nanotechnology and materials science. In particular, DNA-based hydrogels present such remarkable features as stability, flexibility, precise programmability, stimuli-responsive DNA conformations, facile synthesis and modification. Moreover, functional nucleic acids (FNAs) have allowed the construction of hydrogels based on aptamers, DNAzymes, i-motif nanostructures, siRNAs and CpG oligodeoxynucleotides to provide additional molecular recognition, catalytic activities and therapeutic potential, making them key players in biological analysis and biomedical applications. To date, a variety of applications have been demonstrated with FNA-based hydrogels, including biosensing, environmental analysis, controlled drug release, cell adhesion and targeted cancer therapy. In this review, we focus on advances in the development of FNA-based hydrogels, which have fully incorporated both the unique features of FNAs and DNA-based hydrogels. We first introduce different strategies for constructing DNA-based hydrogels. Subsequently, various types of FNAs and the most recent developments of FNA-based hydrogels for bioanalytical and biomedical applications are described with some selected examples. Finally, the review provides an insight into the remaining challenges and future perspectives of FNA-based hydrogels. PMID:26758955

Synthesis and characterization of agricultural controllable humic acid superabsorbent.

PubMed

Gao, Lijuan; Wang, Shiqiang; Zhao, Xuefei

2013-12-01

Humic acid superabsorbent polymer (P(AA/AM-HA)) and superabsorbent polymer (P(AA/AM)) were synthesized by aqueous solution polymerization method using acrylic acid (AA), acrylamide (AM) and humic acid (HA) as raw material. The effects of N,N'-methylenebisacrylamide (MBA) crosslinking agent, potassium peroxydisulfate (KPS) initiator, reaction temperature, HA content, ratio of AA to AM, concentration of monomer and neutralization of AA on water absorption were investigated. Absorption and desorption ratios of nitrogen fertilizer and phosphate fertilizer were also investigated by determination of absorption and desorption ratio of NH4(+), PO4(3-) on P(AA/AM-HA) and P(AA/AM). The P(AA/AM-HA) and P(AA/AM) were characterized by Fourier translation infrared spectroscopy, biological photomicroscope and scanning electron microscopy (SEM). The optimal conditions obtained were as follows: the weight ratio of MBA to AA and AM was 0.003; the weight ratio of KPS to AA and AM was 0.008; the weight ratio of HA to AA was 0.1; the mole ratio of AM to AA is 0.1; the mole ratio of NaOH to AA is 0.9; the reaction temperature was 60°C. P(AA/AM-HA) synthesized under optimal conditions, has a good saline tolerance, its water absorbency in distilled water and 0.9 wt.% saline solution is 1180 g/g and 110 g/g, respectively. P(AA/AM-HA) achieves half saturation in 6.5 min. P(AA/AM-HA) is superior to P(AA/AM) on absorption of NH4(+), PO4(3-). The SEM micrograph of P(AA/AM-HA) shows a fine alveolate structure. The biological optical microscope micrograph of P(AA/AM-HA) shows a network structure. Graft polymerization between P(AA/AM) and HA was demonstrated by infrared spectrum. The P(AA/AM-HA) superabsorbent has better absorbing ability of water and fertilizer, electrolytic tolerance and fewer cost than P(AA/AM) superabsorbent. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Effectiveness of a water-saving super-absorbent polymer in soil water conservation for corn (Zea mays L.) based on eco-physiological parameters.

PubMed

Islam, M Robiul; Hu, Yuegao; Mao, Sishuai; Mao, Jinzhu; Eneji, A Egrinya; Xue, Xuzhang

2011-08-30

The objective was to study soil water conservation and physiological growth of corn (Zea mays L.) using water-saving super-absorbent polymer (SAP) at 30 kg ha(-1). The effectiveness of SAP was studied under three irrigation levels (adequate, moderate and deficit) using a new type of negative hydraulic pressure controlled auto-irrigator in the years 2009 and 2010 in a greenhouse at Beijing, P.R. China. Eight weeks after sowing, plant height and leaf area increased significantly by 41.6 and 79.6% under deficit irrigation for SAP treatment. The SAP had little effect on shoot dry mass under adequate and moderate irrigation but increased it significantly by 133.5% under deficit irrigation. Similarly, the efficiency of water use also increased by 97.1%. Leaf water potential under adequate and moderate irrigation differs slightly for SAP application, whereas under deficit irrigation the values were exceeded significantly by 27.8%. The superior growth and water use efficiency of corn treated with SAP under deficit irrigation was ascribed to maintenance of higher relative water contents in leaves as well as intercellular carbon dioxide concentration, net photosynthesis and transpiration rate. Our results suggested that plant growth and different physiological activities are restricted by drought stress and the application of super-absorbent polymer could conserve soil water, making same available to plants for increased growth and biomass accumulation especially under severe water stress. Thus, application of SAP is a suitable soil management practice for the locations characterised by severe water stress. Copyright © 2011 Society of Chemical Industry.

Silk protein-based hydrogels: Promising advanced materials for biomedical applications.

PubMed

Kapoor, Sonia; Kundu, Subhas C

2016-02-01

Hydrogels are a class of advanced material forms that closely mimic properties of the soft biological tissues. Several polymers have been explored for preparing hydrogels with structural and functional features resembling that of the extracellular matrix. Favourable material properties, biocompatibility and easy processing of silk protein fibers into several forms make it a suitable material for biomedical applications. Hydrogels made from silk proteins have shown a potential in overcoming limitations of hydrogels prepared from conventional polymers. A great deal of effort has been made to control the properties and to integrate novel topographical and functional characteristics in the hydrogel composed from silk proteins. This review provides overview of the advances in silk protein-based hydrogels with a primary emphasis on hydrogels of fibroin. It describes the approaches used to fabricate fibroin hydrogels. Attempts to improve the existing properties or to incorporate new features in the hydrogels by making composites and by improving fibroin properties by genetic engineering approaches are also described. Applications of the fibroin hydrogels in the realms of tissue engineering and controlled release are reviewed and their future potentials are discussed. This review describes the potentiality of silk fibroin hydrogel. Silk Fibroin has been widely recognized as an interesting biomaterial. Due to its properties including high mechanical strength and excellent biocompatibility, it has gained wide attention. Several groups are exploring silk-based materials including films, hydrogels, nanofibers and nanoparticles for different biomedical applications. Although there is a good amount of literature available on general properties and applications of silk based biomaterials, there is an inadequacy of extensive review articles that specifically focus on silk based hydrogels. Silk-based hydrogels have a strong potential to be utilized in biomedical applications. Our work is an effort to highlight the research that has been done in the area of silk-based hydrogels. It aims to provide an overview of the advances that have been made and the future course available. It will provide an overview of the silk-based hydrogels as well as may direct the readers to the specific areas of application. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hydrogel Biomaterials: A Smart Future?

PubMed Central

Kopeček, Jindřich

2007-01-01

Hydrogels were the first biomaterials developed for human use. The state-of-the-art and potential for the future are discussed. Recently, new designs have produced mechanically strong synthetic hydrogels. Protein based hydrogels and hybrid hydrogels containing protein domains present a novel advance; such biomaterials may self-assemble from block or graft copolymers containing biorecognition domains. One of the domains, the coiled-coil, ubiquitously found in nature, has been used as an example to demonstrate the developments in the design of smart hydrogels. The application potential of synthetic, protein-based, DNA-based, and hybrid hydrogels bodes well for the future of this class of biomaterials. PMID:17697712

Polymeric hydrogels for novel contact lens-based ophthalmic drug delivery systems: a review.

PubMed

Xinming, Li; Yingde, Cui; Lloyd, Andrew W; Mikhalovsky, Sergey V; Sandeman, Susan R; Howel, Carol A; Liewen, Liao

2008-04-01

Only about 5% of drugs administrated by eye drops are bioavailable, and currently eye drops account for more than 90% of all ophthalmic formulations. The bioavailability of ophthalmic drugs can be improved by a soft contact lens-based ophthalmic drug delivery system. Several polymeric hydrogels have been investigated for soft contact lens-based ophthalmic drug delivery systems: (i) polymeric hydrogels for conventional contact lens to absorb and release ophthalmic drugs; (ii) polymeric hydrogels for piggyback contact lens combining with a drug plate or drug solution; (iii) surface-modified polymeric hydrogels to immobilize drugs on the surface of contact lenses; (iv) polymeric hydrogels for inclusion of drugs in a colloidal structure dispersed in the lens; (v) ion ligand-containing polymeric hydrogels; (vi) molecularly imprinted polymeric hydrogels which provide the contact lens with a high affinity and selectivity for a given drug. Polymeric hydrogels for these contact lens-based ophthalmic drug delivery systems, their advantages and drawbacks are critically analyzed in this review.

Xylan-Modified-Based Hydrogels with Temperature/pH Dual Sensitivity and Controllable Drug Delivery Behavior

PubMed Central

Kong, Wei-Qing; Gao, Cun-Dian; Hu, Shu-Feng; Ren, Jun-Li; Zhao, Li-Hong; Sun, Run-Cang

2017-01-01

Among the natural macromolecules potentially used as the scaffold material in hydrogels, xylan has aroused great interest in many fields because of its biocompatibility, low toxicity, and biodegradability. In this work, new pH and thermoresponsive hydrogels were prepared by the cross-linking polymerization of maleic anhydride-modified xylan (MAHX) with N-isopropylacrylamide (NIPAm) and acrylic acid (AA) under UV irradiation to form MAHX-g-P(NIPAm-co-AA) hydrogels. The pore volume, the mechanical properties, and the release rate for drugs of hydrogels could be controlled by the degree of substitution of MAHX. These hydrogels were characterized by swelling ability, lower critical solution temperature (LCST), Fourier-transform infrared (FTIR), and SEM. Furthermore, the cumulative release rate was investigated for acetylsalicylic acid and theophylline, as well as the cytocompatibility MAHX-based hydrogels. Results showed that MAHX-based hydrogels exhibited excellent swelling–deswelling properties, uniform porous structure, and the temperature/pH dual sensitivity. In vitro, the cumulative release rate of acetylsalicylic acid for MAHX-based hydrogels was higher than that for theophylline, and in the gastrointestinal sustained drug release study, the acetylsalicylic acid release rate was extremely slow during the initial 3 h in the gastric fluid (24.26%), and then the cumulative release rate reached to 90.5% after sustained release for 5 h in simulated intestinal fluid. The cytotoxicity experiment demonstrated that MAHX-based hydrogels could promote cell proliferation and had satisfactory biocompatibility with NIH3T3 cells. These results indicated that MAHX-based hydrogels, as new drug carriers, had favorable behavior for intestinal-targeted drug delivery. PMID:28772664

An in situ formed biodegradable hydrogel for reconstruction of the corneal endothelium.

PubMed

Liang, Ye; Liu, Wanshun; Han, Baoqin; Yang, Chaozhong; Ma, Qun; Song, Fulai; Bi, Qingqing

2011-01-01

Biodegradable hydrogels are important biomaterials for tissue engineering and drug delivery. For the purpose of corneal regenerative medicine, we describe an in situ formed hydrogel based on a water-soluble derivative of chitosan, hydroxypropyl chitosan (HPCTS), and sodium alginate dialdehyde (SAD). Periodate oxidized alginate rapidly cross-links HPCTS due to Schiff's base formation between the available aldehyde and amino groups. Hydrogel cytotoxicity, degradability and histocompatibility in vivo were examined. The potential of the composite hydrogel for corneal endothelium reconstruction was demonstrated by encapsulating corneal endothelial cells (CECs) to grow on Descemet's membranes. The results demonstrate that the composite hydrogel was both non-toxic and biodegradable and that CECs transplanted by the composite hydrogel could survive and retain normal morphology. These results provide an opportunity for corneal endothelium reconstruction based on tissue engineering by the in situ formed composite hydrogel. Copyright © 2010 Elsevier B.V. All rights reserved.

Protease-modulating polyacrylate-based hydrogel stimulates wound bed preparation in venous leg ulcers – a randomized controlled trial

PubMed Central

Humbert, P; Faivre, B; Véran, Y; Debure, C; Truchetet, F; Bécherel, P-A; Plantin, P; Kerihuel, J-C; Eming, SA; Dissemond, J; Weyandt, G; Kaspar, D; Smola, H; Zöllner, P

2014-01-01

Background Stringent control of proteolytic activity represents a major therapeutic approach for wound-bed preparation. Objectives We tested whether a protease-modulating polyacrylate- (PA-) containing hydrogel resulted in a more efficient wound-bed preparation of venous leg ulcers when compared to an amorphous hydrogel without known protease-modulating properties. Methods Patients were randomized to the polyacrylate-based hydrogel (n = 34) or to an amorphous hydrogel (n = 41). Wound beds were evaluated by three blinded experts using photographs taken on days 0, 7 and 14. Results After 14 days of treatment there was an absolute decrease in fibrin and necrotic tissue of 37.6 ± 29.9 percentage points in the PA-based hydrogel group and by 16.8 ± 23.0 percentage points in the amorphous hydrogel group. The absolute increase in the proportion of ulcer area covered by granulation tissue was 36.0 ± 27.4 percentage points in the PA-based hydrogel group and 14.5 ± 22.0 percentage points in the control group. The differences between the groups were significant (decrease in fibrin and necrotic tissue P = 0.004 and increase in granulation tissue P = 0.0005, respectively). Conclusion In particular, long-standing wounds profited from the treatment with the PA-based hydrogel. These data suggest that PA-based hydrogel dressings can stimulate normalization of the wound environment, particularly in hard-to-heal ulcers. PMID:24612304

Glow discharge electrolysis plasma initiated preparation of temperature/pH dual sensitivity reed hemicellulose-based hydrogels.

PubMed

Zhang, Wenming; Zhu, Sha; Bai, Yunping; Xi, Ning; Wang, Shaoyang; Bian, Yang; Li, Xiaowei; Zhang, Yucang

2015-05-20

The temperature/pH dual sensitivity reed hemicellulose-based hydrogels have been prepared through glow discharge electrolysis plasma (GDEP). The effect of different discharge voltages on the temperature and pH response performance of reed hemicellulose-based hydrogels was inspected, and the formation mechanism, deswelling behaviors of reed hemicellulose-based hydrogels were also discussed. At the same time, infrared spectroscopy (FT-IR), scanning differential thermal analysis (DSC) and scanning electron microscope (SEM) were adopted to characterize the structure, phase transformation behaviors and microstructure of hydrogels. It turned out to be that all reed hemicellulose-based hydrogels had a double sensitivity to temperature and pH, and their phase transition temperatures were all approximately 33 °C, as well as the deswelling dynamics met the first model. In addition, the hydrogel (TPRH-3), under discharge voltage 600 V, was more sensitive to temperature and pH and had higher deswelling ratio. Copyright © 2015 Elsevier Ltd. All rights reserved.

Angiogenic potential of gellan-gum-based hydrogels for application in nucleus pulposus regeneration: in vivo study.

PubMed

Silva-Correia, Joana; Miranda-Gonçalves, Vera; Salgado, António J; Sousa, Nuno; Oliveira, Joaquim M; Reis, Rui M; Reis, Rui L

2012-06-01

Hydrogels for nucleus pulposus (NP) regeneration should be able to comprise a nonangiogenic or even antiangiogenic feature. Gellan gum (GG)-based hydrogels have been reported to possess adequate properties for being used as NP substitutes in acellular and cellular strategies, due to its ability to support cell encapsulation, adequate mechanical properties, and noncytotoxicity. In this study, the angiogenic response of GG-based hydrogels was investigated by performing the chorioallantoic membrane assay. The convergence of macroscopic blood vessels toward the GG, ionic-crosslinked methacrylated GG (iGG-MA), and photo-crosslinked methacrylated GG (phGG-MA) hydrogel discs was quantified. Gelatin sponge (GSp) and filter paper (FP) alone and with vascular endothelial growth factor were used as controls of angiogenesis. The images obtained were digitally processed and analyzed by three independent observers. The macroscopic blood vessel quantification demonstrated that the GG-based hydrogels are not angiogenic as compared with FP controls. No statistical differences between the GG-based hydrogels tested in respect to its angiogenic ability were observed. Hematoxylin and eosin staining and SNA-lectin immunohistochemistry assay indicated that the iGG-MA and phGG-MA hydrogels do not allow the ingrowth of chick endothelial cells, following 4 days of implantation. On the contrary, GG, GSp, and FP controls allowed cell infiltration. The histological data also indicated that the GG-based hydrogels do not elicit any acute inflammatory response. The results showed that the GG, iGG-MA, and phGG-MA hydrogels present different permeability to cells but functioned as a physical barrier for vascular invasion. These hydrogels present promising and tunable properties for being used as NP substitutes in the treatment of degenerative intervertebral disc.

3D-Hydrogel Based Polymeric Nanoreactors for Silver Nano-Antimicrobial Composites Generation.

PubMed

Soto-Quintero, Albanelly; Romo-Uribe, Ángel; Bermúdez-Morales, Víctor H; Quijada-Garrido, Isabel; Guarrotxena, Nekane

2017-08-01

This study underscores the development of Ag hydrogel nanocomposites, as smart substrates for antibacterial uses, via innovative in situ reactive and reduction pathways. To this end, two different synthetic strategies were used. Firstly thiol-acrylate (PSA) based hydrogels were attained via thiol-ene and radical polymerization of polyethylene glycol (PEG) and polycaprolactone (PCL). As a second approach, polyurethane (PU) based hydrogels were achieved by condensation polymerization from diisocyanates and PCL and PEG diols. In fact, these syntheses rendered active three-dimensional (3D) hydrogel matrices which were used as nanoreactors for in situ reduction of AgNO₃ to silver nanoparticles. A redox chemistry of stannous catalyst in PU hydrogel yielded spherical AgNPs formation, even at 4 °C in the absence of external reductant; and an appropriate thiol-functionalized polymeric network promoted spherical AgNPs well dispersed through PSA hydrogel network, after heating up the swollen hydrogel at 103 °C in the presence of citrate-reductant. Optical and swelling behaviors of both series of hydrogel nanocomposites were investigated as key factors involved in their antimicrobial efficacy over time. Lastly, in vitro antibacterial activity of Ag loaded hydrogels exposed to Pseudomona aeruginosa and Escherichia coli strains indicated a noticeable sustained inhibitory effect, especially for Ag-PU hydrogel nanocomposites with bacterial inhibition growth capabilities up to 120 h cultivation.

Protein-based hydrogels for tissue engineering

PubMed Central

Schloss, Ashley C.; Williams, Danielle M.; Regan, Lynne J.

2017-01-01

The tunable mechanical and structural properties of protein-based hydrogels make them excellent scaffolds for tissue engineering and repair. Moreover, using protein-based components provides the option to insert sequences associated with the promoting both cellular adhesion to the substrate and overall cell growth. Protein-based hydrogel components are appealing for their structural designability, specific biological functionality, and stimuli-responsiveness. Here we present highlights in the field of protein-based hydrogels for tissue engineering applications including design requirements, components, and gel types. PMID:27677513

Synthesis of Acylated Xylan-Based Magnetic Fe3O4 Hydrogels and Their Application for H2O2 Detection

PubMed Central

Dai, Qing-Qing; Ren, Jun-Li; Peng, Feng; Chen, Xiao-Feng; Gao, Cun-Dian; Sun, Run-Cang

2016-01-01

Acylated xylan-based magnetic Fe3O4 nanocomposite hydrogels (ACX-MNP-gels) were prepared by fabricating Fe3O4 nanoctahedra in situ within a hydrogel matrix which was synthesized by the copolymerization of acylated xylan (ACX) with acrylamide and N-isopropylacrylamide under ultraviolet irradiation. The size of the Fe3O4 fabricated within the hydrogel matrix could be adjusted through controlling the crosslinking concentrations (C). The magnetic hydrogels showed desirable magnetic and mechanical properties, which were confirmed by XRD, Raman spectroscopy, physical property measurement system, SEM, TGA, and compression test. Moreover, the catalytic performance of the magnetic hydrogels was explored. The magnetic hydrogels (C = 7.5 wt %) presented excellent catalytic activity and provided a sensitive response to H2O2 detection even at a concentration level of 5 × 10−6 mol·L−1. This approach to preparing magnetic hydrogels loaded with Fe3O4 nanoparticles endows xylan-based hydrogels with new promising applications in biotechnology and environmental chemistry. PMID:28773811

Reversible Modulation of DNA-Based Hydrogel Shapes by Internal Stress Interactions.

PubMed

Hu, Yuwei; Kahn, Jason S; Guo, Weiwei; Huang, Fujian; Fadeev, Michael; Harries, Daniel; Willner, Itamar

2016-12-14

We present the assembly of asymmetric two-layer hybrid DNA-based hydrogels revealing stimuli-triggered reversibly modulated shape transitions. Asymmetric, linear hydrogels that include layer-selective switchable stimuli-responsive elements that control the hydrogel stiffness are designed. Trigger-induced stress in one of the layers results in the bending of the linear hybrid structure, thereby minimizing the elastic free energy of the systems. The removal of the stress by a counter-trigger restores the original linear bilayer hydrogel. The stiffness of the DNA hydrogel layers is controlled by thermal, pH (i-motif), K + ion/crown ether (G-quadruplexes), chemical (pH-doped polyaniline), or biocatalytic (glucose oxidase/urease) triggers. A theoretical model relating the experimental bending radius of curvatures of the hydrogels with the Young's moduli and geometrical parameters of the hydrogels is provided. Promising applications of shape-regulated stimuli-responsive asymmetric hydrogels include their use as valves, actuators, sensors, and drug delivery devices.

Biodegradation and Osteosarcoma Cell Cultivation on Poly(aspartic acid) Based Hydrogels.

PubMed

Juriga, Dávid; Nagy, Krisztina; Jedlovszky-Hajdú, Angéla; Perczel-Kovách, Katalin; Chen, Yong Mei; Varga, Gábor; Zrínyi, Miklós

2016-09-14

Development of novel biodegradable and biocompatible scaffold materials with optimal characteristics is important for both preclinical and clinical applications. The aim of the present study was to analyze the biodegradability of poly(aspartic acid)-based hydrogels, and to test their usability as scaffolds for MG-63 osteoblast-like cells. Poly(aspartic acid) was fabricated from poly(succinimide) and hydrogels were prepared using natural amines as cross-linkers (diaminobutane and cystamine). Disulfide bridges were cleaved to thiol groups and the polymer backbone was further modified with RGD sequence. Biodegradability of the hydrogels was evaluated by experiments on the base of enzymes and cell culture medium. Poly(aspartic acid) hydrogels possessing only disulfide bridges as cross-links proved to be degradable by collagenase I. The MG-63 cells showed healthy, fibroblast-like morphology on the double cross-linked and RGD modified hydrogels. Thiolated poly(aspartic acid) based hydrogels provide ideal conditions for adhesion, survival, proliferation, and migration of osteoblast-like cells. The highest viability was found on the thiolated PASP gels while the RGD motif had influence on compacted cluster formation of the cells. These biodegradable and biocompatible poly(aspartic acid)-based hydrogels are promising scaffolds for cell cultivation.

Chitosan based hydrogels: characteristics and pharmaceutical applications

PubMed Central

Ahmadi, F.; Oveisi, Z.; Samani, S. Mohammadi; Amoozgar, Z.

2015-01-01

Hydrogel scaffolds serve as semi synthetic or synthetic extra cellular matrix to provide an amenable environment for cellular adherence and cellular remodeling in three dimensional structures mimicking that of natural cellular environment. Additionally, hydrogels have the capacity to carry small molecule drugs and/or proteins, growth factors and other necessary components for cell growth and differentiation. In the context of drug delivery, hydrogels can be utilized to localize drugs, increase drugs concentration at the site of action and consequently reduce off-targeted side effects. The current review aims to describe and classify hydrogels and their methods of production. The main highlight is chitosan-based hydrogels as biocompatible and medically relevant hydrogels for drug delivery. PMID:26430453

A comparative study on collagen type I and hyaluronic acid dependent cell behavior for osteochondral tissue bioprinting.

PubMed

Park, Ju Young; Choi, Jong-Cheol; Shim, Jin-Hyung; Lee, Jung-Seob; Park, Hyoungjun; Kim, Sung Won; Doh, Junsang; Cho, Dong-Woo

2014-09-01

Bioprinting is a promising technique for engineering composite tissues, such as osteochondral tissues. In this study, as a first step toward bioprinting-based osteochondral tissue regeneration, we systematically examined the behavior of chondrocytes and osteoblasts to hyaluronic acid (HA) and type I collagen (Col-1) hydrogels. First, we demonstrated that cells on hydrogels that were comprised of major native tissue extracellular matrix (ECM) components (i.e. chondrocytes on HA hydrogels and osteoblasts on Col-1 hydrogels) exhibited better proliferation and cell function than cells on non-native ECM hydrogels (i.e., chondrocytes on Col-1 hydrogels and osteoblasts on HA hydrogels). In addition, cells located near their native ECM hydrogels migrated towards them. Finally, we bioprinted three-dimensional (3D) osteochondral tissue-mimetic structures composed of two compartments, osteoblast-encapsulated Col-1 hydrogels and chondrocyte-encapsulated HA hydrogels, and found viability and functions of each cell type were well maintained within the 3D structures up to 14 days in vitro. These results suggest that with proper choice of hydrogel materials, bioprinting-based approaches can be successfully applied for osteochondral tissue regeneration.

Synthesis, characterization, and evaluation of poly(aminoethyl) modified chitosan and its hydrogel used as antibacterial wound dressing.

PubMed

Zhang, Yubei; Dang, Qifeng; Liu, Chengsheng; Yan, Jingquan; Cha, Dongsu; Liang, Shengnan; Li, Xiaoli; Fan, Bing

2017-09-01

This study aims to develop new antibacterial hydrogel wound dressings composed of poly(aminoethyl) modified chitosan (PAEMCS). FTIR, 1 H NMR, and elemental analysis demonstrated that PAEMCS was successfully synthesized via grafting poly(aminoethyl) groups onto hydroxyl groups on chitin first, and removing acetyl groups from the grafted polymer afterward. XRD and TGA implied its well-defined crystallinity and thermostability. Furthermore, a series of hydrogels were fabricated under the participation of dipotassium hydrogen phosphate (DHP). The gelation tests suggested that the higher concentration of PAEMCS or DHP was beneficial to the formation of hydrogels. The pH values of hydrogels at 37°C were all in the range of 7.12-7.50. The rheological tests indicated that PAEMCS-based hydrogels were of lower DHP addition and higher elasticity than CS-based hydrogels to achieve the same gelation temperature under the same polymer's concentration. Additionally, the swelling, anti-bacteria, and cytotoxicity experiments showed that PAEMCS-based hydrogels possessed excellent hygroscopicity, high antibacterial activity against E. coli, S. aureus, or S. epidermidis, and good cytocompatibility toward L929 cells or HUVECs, respectively. All the results implied that PAEMCS-based hydrogels not only maintained inherent multiple properties of chitosan but also possessed excellent antibacterial activity, and might be promising antibacterial hydrogel dressings used in wound therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Superabsorbent Polymers: An Idea Whose Time Has Come

NASA Astrophysics Data System (ADS)

Buchholz, Fredric L.

1996-06-01

Superabsorbent polymers are cross-linked polyelectrolytes. Because of their ionic nature and interconnected structure, they absorb large quantities of water and other aqueous solutions without dissolving. This makes them ideally suited as absorbents of body fluids in many personal care products sold today, including baby diapers, adult incontinence products, and feminine napkins. Several emerging applications are also described. A simple laboratory preparation of partially neutralized, cross-linked poly(acrylic acid) is given along with test methods suitable for measuring the absorption capacity of the product. Experiments are described that demonstrate the ability of a swelling gel to perform work, and the ability of a gel to exclude macromolecular solutes from diffusing into its porous, cross-linked structure.

Polysaccharide-based hydrogels with tunable composition as 3D cell culture systems.

PubMed

Gentilini, Roberta; Munarin, Fabiola; Bloise, Nora; Secchi, Eleonora; Visai, Livia; Tanzi, Maria Cristina; Petrini, Paola

2018-04-01

To date, cell cultures have been created either on 2-dimensional (2D) polystyrene surfaces or in 3-dimensional (3D) systems, which do not offer a controlled chemical composition, and which lack the soft environment encountered in vivo and the chemical stimuli that promote cell proliferation and allow complex cellular behavior. In this study, pectin-based hydrogels were developed and are proposed as versatile cell culture systems. Pectin-based hydrogels were produced by internally crosslinking pectin with calcium carbonate at different initial pH, aiming to control crosslinking kinetics and degree. Additionally, glucose and glutamine were added as additives, and their effects on the viscoelastic properties of the hydrogels and on cell viability were investigated. Pectin hydrogels showed in high cell viability and shear-thinning behavior. Independently of hydrogel composition, an initial swelling was observed, followed by a low percentage of weight variation and a steady-state stage. The addition of glucose and glutamine to pectin-based hydrogels rendered higher cell viability up to 90%-98% after 1 hour of incubation, and these hydrogels were maintained for up to 7 days of culture, yet no effect on viscoelastic properties was detected. Pectin-based hydrogels that offer tunable composition were developed successfully. They are envisioned as synthetic extracellular matrix (ECM) either to study complex cellular behaviors or to be applied as tissue engineering substitutes.

Hydrogel-based three-dimensional cell culture for organ-on-a-chip applications.

PubMed

Lee, Seung Hwan; Shim, Kyu Young; Kim, Bumsang; Sung, Jong Hwan

2017-05-01

Recent studies have reported that three-dimensionally cultured cells have more physiologically relevant functions than two-dimensionally cultured cells. Cells are three-dimensionally surrounded by the extracellular matrix (ECM) in complex in vivo microenvironments and interact with the ECM and neighboring cells. Therefore, replicating the ECM environment is key to the successful cell culture models. Various natural and synthetic hydrogels have been used to mimic ECM environments based on their physical, chemical, and biological characteristics, such as biocompatibility, biodegradability, and biochemical functional groups. Because of these characteristics, hydrogels have been combined with microtechnologies and used in organ-on-a-chip applications to more closely recapitulate the in vivo microenvironment. Therefore, appropriate hydrogels should be selected depending on the cell types and applications. The porosity of the selected hydrogel should be controlled to facilitate the movement of nutrients and oxygen. In this review, we describe various types of hydrogels, external stimulation-based gelation of hydrogels, and control of their porosity. Then, we introduce applications of hydrogels for organ-on-a-chip. Last, we also discuss the challenges of hydrogel-based three-dimensional cell culture techniques and propose future directions. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:580-589, 2017. © 2017 American Institute of Chemical Engineers.

3D-Hydrogel Based Polymeric Nanoreactors for Silver Nano-Antimicrobial Composites Generation

PubMed Central

Soto-Quintero, Albanelly; Romo-Uribe, Ángel; Bermúdez-Morales, Víctor H.; Quijada-Garrido, Isabel

2017-01-01

This study underscores the development of Ag hydrogel nanocomposites, as smart substrates for antibacterial uses, via innovative in situ reactive and reduction pathways. To this end, two different synthetic strategies were used. Firstly thiol-acrylate (PSA) based hydrogels were attained via thiol-ene and radical polymerization of polyethylene glycol (PEG) and polycaprolactone (PCL). As a second approach, polyurethane (PU) based hydrogels were achieved by condensation polymerization from diisocyanates and PCL and PEG diols. In fact, these syntheses rendered active three-dimensional (3D) hydrogel matrices which were used as nanoreactors for in situ reduction of AgNO3 to silver nanoparticles. A redox chemistry of stannous catalyst in PU hydrogel yielded spherical AgNPs formation, even at 4 °C in the absence of external reductant; and an appropriate thiol-functionalized polymeric network promoted spherical AgNPs well dispersed through PSA hydrogel network, after heating up the swollen hydrogel at 103 °C in the presence of citrate-reductant. Optical and swelling behaviors of both series of hydrogel nanocomposites were investigated as key factors involved in their antimicrobial efficacy over time. Lastly, in vitro antibacterial activity of Ag loaded hydrogels exposed to Pseudomona aeruginosa and Escherichia coli strains indicated a noticeable sustained inhibitory effect, especially for Ag–PU hydrogel nanocomposites with bacterial inhibition growth capabilities up to 120 h cultivation. PMID:28763050

Nanofiber-structured hydrogel yarns with pH-response capacity and cardiomyocyte-drivability for bio-microactuator application.

PubMed

Wu, Shaohua; Duan, Bin; Qin, Xiaohong; Butcher, Jonathan T

2017-09-15

Polymeric hydrogels have great potential in soft biological micro-actuator applications. However, inappropriate micro-architecture, non-anisotropy, weak biomechanics, and inferior response behaviors limit their development. In this study, we designed and manufactured novel polyacrylonitrile (PAN)-based hydrogel yarns composed with uniaxially aligned nanofibers. The nanofibrous hydrogel yarns possessed anisotropic architecture and robust mechanical properties with flexibility, and could be assembled into defined scaffold structures by subsequent processes. The as-prepared hydrogel yarns showed excellent pH response behaviors, with around 100% maximum length and 900% maximum diameter changes, and the pH response was completed within several seconds. Moreover, the hydrogel yarns displayed unique cell-responsive abilities to promote the cell adhesion, proliferation, and smooth muscle differentiation of human adipose derived mesenchymal stem cells (HADMSC). Chicken cardiomyocytes were further seeded onto our nanofibrous hydrogel yarns to engineer living cell-based microactuators. Our results demonstrated that the uniaxially aligned nanofibrous networks within the hydrogel yarns were the key characteristics leading to the anisotropic organization of cardiac cells, and improved sarcomere organization, mimicking the cardiomyocyte bundles in the native myocardium. The construct is capable of sustaining spontaneous cardiomyocyte pumping behaviors for 7days. Our PAN-based nanofibrous hydrogel yarns are attractive for creating linear microactuators with pH-response capacity and biological microactuators with cardiomyocyte-drivability. A mechanically robust polyacrylonitrile-based nanofibrous hydrogel yarn is fabricated by using a modified electrospinning setup in combination with chemical modification processes. The as-prepared hydrogel yarn possesses a uniaxially aligned nanofiber microarchitecture and supports a rapid, pH-dependent expansion/contraction response within a few seconds. Embryonic cardiomyocytes-seeded hydrogel yarn improves the sarcomere organization and mimics the cardiomyocyte bundles in the native myocardium, which sustains spontaneous cardiomyocyte pumping behaviors. The nanofibrous hydrogel yarn has several advantages over traditional bulk hydrogel scaffolds in terms of robust biomechanics, anisotropic aligned architecture, and superior pH response behaviors. Our nanofibrous hydrogel yarn holds the potential to be developed into novel linear and biological microactuators for various biomedical applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Surface wettability enhancement of silicone hydrogel lenses by processing with polar plastic molds.

PubMed

Lai, Y C; Friends, G D

1997-06-05

In the quest for hydrogel contact lenses with improved extended wear capability, the use of siloxane moieties in the lens materials was investigated. However, the introduction of hydrophobic siloxane groups gave rise to wettability and lipidlike deposit problems. It was found that when polysiloxane-based compositions for hydrogels were processed with polar plastic molds, such as those fabricated from an acrylonitrile-based polymer, the hydrogel lenses fabricated were wettable, with minimized lipidlike deposits. These findings were supported by the wettability of silicone hydrogel films, silicon, and nitrogen element contents near lens surfaces, as well as the results from clinical assessment of silicone hydrogel lenses.

On the development of multifunctional luminescent supramolecular hydrogel of gold and egg white

NASA Astrophysics Data System (ADS)

Patra, Sudeshna; Ravulapalli, Sathyavathi; Hahm, Myung Gwan; Tadi, Kiran Kumar; Narayanan, Tharangattu N.

2016-10-01

Highly stable, luminescent, and printable/paintable supramolecular egg white hydrogel-based surface enhanced Raman scattering (SERS) matrix is created by an in situ synthesis of gold clusters inside a luminescent egg white hydrogel (Au-Gel). The synthesis of stable luminescent egg-white-based hydrogel, where the hydrogel can act as a three dimensional (3D) matrix, using a simple cross-linking chemistry, has promising application in the biomedical field including in 3D cell culturing. Furthermore, this functional hydrogel is demonstrated for micromolar-level detection of Rhodamine 6G using the SERS technique, where Au-Gel is painted over a flexible cellulose pad.

Material properties that predict preservative uptake for silicone hydrogel contact lenses.

PubMed

Green, J Angelo; Phillips, K Scott; Hitchins, Victoria M; Lucas, Anne D; Shoff, Megan E; Hutter, Joseph C; Rorer, Eva M; Eydelman, Malvina B

2012-11-01

To assess material properties that affect preservative uptake by silicone hydrogel lenses. We evaluated the water content (using differential scanning calorimetry), effective pore size (using probe penetration), and preservative uptake (using high-performance liquid chromatography with spectrophotometric detection) of silicone and conventional hydrogel soft contact lenses. Lenses grouped similarly based on freezable water content as they did based on total water content. Evaluation of the effective pore size highlighted potential differences between the surface-treated and non-surface-treated materials. The water content of the lens materials and ionic charge are associated with the degree of preservative uptake. The current grouping system for testing contact lens-solution interactions separates all silicone hydrogels from conventional hydrogel contact lenses. However, not all silicone hydrogel lenses interact similarly with the same contact lens solution. Based upon the results of our research, we propose that the same material characteristics used to group conventional hydrogel lenses, water content and ionic charge, can also be used to predict uptake of hydrophilic preservatives for silicone hydrogel lenses. In addition, the hydrophobicity of silicone hydrogel contact lenses, although not investigated here, is a unique contact lens material property that should be evaluated for the uptake of relatively hydrophobic preservatives and tear components.

pH-responsive self-healing injectable hydrogel based on N-carboxyethyl chitosan for hepatocellular carcinoma therapy.

PubMed

Qu, Jin; Zhao, Xin; Ma, Peter X; Guo, Baolin

2017-08-01

Injectable hydrogels with pH-responsiveness and self-healing ability have great potential for anti-cancer drug delivery. Herein, we developed a series of polysaccharide-based self-healing hydrogels with pH-sensitivity as drug delivery vehicles for hepatocellular carcinoma therapy. The hydrogels were prepared by using N-carboxyethyl chitosan (CEC) synthesized via Michael reaction in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) (PEGDA). Doxorubicin (Dox), as a model of water-soluble small molecule anti-cancer drug was encapsulated into the hydrogel in situ. Self-healing behavior of the hydrogels was investigated at microscopic and macroscopic levels, and the hydrogels showed rapid self-healing performance without any external stimulus owing to the dynamic covalent Schiff-base linkage between amine groups from CEC and benzaldehyde groups from PEGDA. The chemical structures, rheological property, in vitro gel degradation, morphology, gelation time and in vitro Dox release behavior from the hydrogels were characterized. Injectability was verified by in vitro injection and in vivo subcutaneous injection in a rat. pH-responsive behavior was verified by in vitro Dox release from hydrogels in PBS solutions with different pH values. Furthermore, the activity of Dox released from hydrogel matrix was evaluated by employing human hepatocellular liver carcinoma (HepG2). Cytotoxicity test of the hydrogels using L929 cells confirmed their good cytocompatibility. Together, these pH-responsive self-healing injectable hydrogels are excellent candidates as drug delivery vehicles for liver cancer treatment. STATEMENT OF SIGNIFICANCE: pH-responsive drug delivery system could release drug efficiently in targeted acid environment and minimalize the amount of drug release in normal physiological environment. pH-sensitive injectable hydrogels as smart anti-cancer drug delivery carriers show great potential application for cancer therapy. The hydrogels with self-healing property could prolong their lifetime during implantation and provide the advantage of minimally invasive surgery and high drug-loading ratio. This work reported the design of a series of pH-responsive self-healing injectable hydrogels based on N-carboxyethyl chitosan synthesized in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) via a green approach, and demonstrated their potential as intelligent delivery vehicle of doxorubicin for hepatocellular carcinoma therapy via the pH-responsive nature of dynamic Schiff base. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Prodrugs as self-assembled hydrogels: a new paradigm for biomaterials.

PubMed

Vemula, Praveen Kumar; Wiradharma, Nikken; Ankrum, James A; Miranda, Oscar R; John, George; Karp, Jeffrey M

2013-12-01

Prodrug-based self-assembled hydrogels represent a new class of active biomaterials that can be harnessed for medical applications, in particular the design of stimuli responsive drug delivery devices. In this approach, a promoiety is chemically conjugated to a known-drug to generate an amphiphilic prodrug that is capable of forming self-assembled hydrogels. Prodrug-based self-assembled hydrogels are advantageous as they alter the solubility of the drug, enhance drug loading, and eliminate the use of harmful excipients. In addition, self-assembled prodrug hydrogels can be designed to undergo controlled drug release or tailored degradation in response to biological cues. Herein we review the development of prodrug-based self-assembled hydrogels as an emerging class of biomaterials that overcome several common limitations encountered in conventional drug delivery. Published by Elsevier Ltd.

Responsive Hydrogel-based Photonic Nanochains for Microenvironment Sensing and Imaging in Real Time and High Resolution.

PubMed

Luo, Wei; Cui, Qian; Fang, Kai; Chen, Ke; Ma, Huiru; Guan, Jianguo

2018-01-17

Microenvironment sensing and imaging are of importance in microscale zones like microreactors, microfluidic systems, and biological cells. But they are so far implemented only based on chemical colors from dyes or quantum dots, which suffered either from photobleaching, quenching, or photoblinking behaviors, or from limited color gamut. In contrast, structural colors from hydrogel-based photonic crystals (PCs) may be stable and tunable in the whole visible spectrum by diffraction peak shift, facilitating the visual detection with high accuracy. However, the current hydrogel-based PCs are all inappropriate for microscale detection due to the bulk size. Here we demonstrate the smallest hydrogel-based PCs, responsive hydrogel-based photonic nanochains with high-resolution and real-time response, by developing a general hydrogen bond-guided template polymerization method. A variety of mechanically separated stimuli-responsive hydrogel-based photonic nanochains have been obtained in a large scale including those responding to pH, solvent, and temperature. Each of them has a submicrometer diameter and is composed of individual one-dimensional periodic structure of magnetic particles locked by a tens-of-nanometer-thick peapod-like responsive hydrogel shell. Taking the pH-responsive hydrogel-based photonic nanochains, for example, pH-induced hydrogel volume change notably alters the nanochain length, resulting in a significant variation of the structural color. The submicrometer size endows the nanochains with improved resolution and response time by 2-3 orders of magnitude than the previous counterparts. Our results for the first time validate the feasibility of using structural colors for microenvironment sensing and imaging and may further promote the applications of responsive PCs, such as in displays and printing.

A Supramolecular Hydrogel Based on Polyglycerol Dendrimer-Specific Amino Group Recognition.

PubMed

Cho, Ik Sung; Ooya, Tooru

2018-05-24

Dendrimer-based supramolecular hydrogels have gained attention in biomedical fields. While biocompatible dendrimers were used to prepare hydrogels via physical and/or chemical crosslinking, smart functions such as pH and molecular control remain undeveloped. Here, we present polyglycerol dendrimer-based supramolecular hydrogel formation induced by a specific interaction between the polyglycerol dendrimer and an amino group of glycol chitosan. Gelation was achieved by mixing the two aqueous solutions. Hydrogel formation was controlled by varying the polyglycerol dendrimer generation. The hydrogel showed pH-dependent swelling; strongly acidic conditions induced degradation via dissociation of the specific interaction. It also showed unique L-arginine-responsive degradation capability due to competitive exchange of the amino groups of glycol chitosan and L-arginine. These polyglycerol dendrimer-based supramolecular characteristics allow multimodal application in smart biomaterials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the surface morphology of biocompatible chitosan-based hydrogels and xerogels

NASA Astrophysics Data System (ADS)

Zhuravleva, Yulia Yu.; Malinkina, Olga N.; Shipovskaya, Anna B.

2018-04-01

Our biocompatible hydrogel systems obtained by the sol-gel technqiue and based on chitosan and silicon polyolates are promising for medical and biological applications. The surface microrelief of these sol-gel materials (hydrogels and xerogels) based on chitosan and silicon tetraglycerolate was explored by AFM and SEM. A significant influence of the component ratio in the mixed system on the morphology and surface profile of the hydrogels and xerogels prepared therefrom was established. An increased content of the structure-forming component (chitosan) in the system was shown to increase the roughness scale of the hydrogel surface and to promote the porosity of the xerogel structure.

Hydrogel Based Biosensors for In Vitro Diagnostics of Biochemicals, Proteins, and Genes.

PubMed

Jung, Il Young; Kim, Ji Su; Choi, Bo Ram; Lee, Kyuri; Lee, Hyukjin

2017-06-01

Hydrogel-based biosensors have drawn considerable attention due to their various advantages over conventional detection systems. Recent studies have shown that hydrogel biosensors can be excellent alternative systems to detect a wide range of biomolecules, including small biochemicals, pathogenic proteins, and disease specific genes. Due to the excellent physical properties of hydrogels such as the high water content and stimuli-responsive behavior of cross-linked network structures, this system can offer substantial improvement for the design of novel detection systems for various diagnostic applications. The other main advantage of hydrogels is the role of biomimetic three-dimensional (3D) matrix immobilizing enzymes and aptamers within the detection systems, which enhances their stability. This provides ideal reaction conditions for enzymes and aptamers to interact with substrates within the aqueous environment of the hydrogel. In this review, we have highlighted various novel detection approaches utilizing the outstanding properties of the hydrogel. This review summarizes the recent progress of hydrogel-based biosensors and discusses their future perspectives and clinical limitations to overcome. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanical characterization and modeling of sponge-reinforced hydrogel composites under compression.

PubMed

Wu, Lei; Mao, Guoyong; Nian, Guodong; Xiang, Yuhai; Qian, Jin; Qu, Shaoxing

2018-05-30

Load-bearing applications of hydrogels call for materials with excellent mechanical properties. Despite the considerable progress in developing tough hydrogels, there is still a requirement to prepare high-performance hydrogels using simple strategies. In this paper, a sponge-reinforced hydrogel composite is synthesized by combining poly(acrylamide) (PAAm) hydrogel and polyurethane (PU) sponge. Uniaxial compressive testing of the hydrogel composites reveals that both the compressive modulus and the strength of the hydrogel composites are much higher than those of the PAAm hydrogel or sponge. In order to predict the compressive modulus of the hydrogel composite, we develop a theoretical model that is validated by experiments and numerical simulations. The present work may guide the design and manufacture of hydrogel-based composite materials, especially for biomaterial scaffolds and soft transducers.

Biocompatibility of hydrogel-based scaffolds for tissue engineering applications.

PubMed

Naahidi, Sheva; Jafari, Mousa; Logan, Megan; Wang, Yujie; Yuan, Yongfang; Bae, Hojae; Dixon, Brian; Chen, P

2017-09-01

Recently, understanding of the extracellular matrix (ECM) has expanded rapidly due to the accessibility of cellular and molecular techniques and the growing potential and value for hydrogels in tissue engineering. The fabrication of hydrogel-based cellular scaffolds for the generation of bioengineered tissues has been based on knowledge of the composition and structure of ECM. Attempts at recreating ECM have used either naturally-derived ECM components or synthetic polymers with structural integrity derived from hydrogels. Due to their increasing use, their biocompatibility has been questioned since the use of these biomaterials needs to be effective and safe. It is not surprising then that the evaluation of biocompatibility of these types of biomaterials for regenerative and tissue engineering applications has been expanded from being primarily investigated in a laboratory setting to being applied in the multi-billion dollar medicinal industry. This review will aid in the improvement of design of non-invasive, smart hydrogels that can be utilized for tissue engineering and other biomedical applications. In this review, the biocompatibility of hydrogels and design criteria for fabricating effective scaffolds are examined. Examples of natural and synthetic hydrogels, their biocompatibility and use in tissue engineering are discussed. The merits and clinical complications of hydrogel scaffold use are also reviewed. The article concludes with a future outlook of the field of biocompatibility within the context of hydrogel-based scaffolds. Copyright © 2017 Elsevier Inc. All rights reserved.

Extracellular-Matrix-Based and Arg-Gly-Asp–Modified Photopolymerizing Hydrogels for Cartilage Tissue Engineering

PubMed Central

Kim, Hwan D.; Heo, Jiseung; Hwang, Yongsung; Kwak, Seon-Yeong; Park, Ok Kyu; Kim, Hyunbum; Varghese, Shyni

2015-01-01

Articular cartilage damage is a persistent and increasing problem with the aging population. Strategies to achieve complete repair or functional restoration remain a challenge. Photopolymerizing-based hydrogels have long received an attention in the cartilage tissue engineering, due to their unique bioactivities, flexible method of synthesis, range of constituents, and desirable physical characteristics. In the present study, we have introduced unique bioactivity within the photopolymerizing-based hydrogels by copolymerizing polyethylene glycol (PEG) macromers with methacrylated extracellular matrix (ECM) molecules (hyaluronic acid and chondroitin sulfate [CS]) and integrin binding peptides (RGD peptide). Results indicate that cellular morphology, as observed by the actin cytoskeleton structures, was strongly dependent on the type of ECM component as well as the presence of integrin binding moieties. Further, CS-based hydrogel with integrin binding RGD moieties increased the lubricin (or known as superficial zone protein [SZP]) gene expression of the encapsulated chondrocytes. Additionally, CS-based hydrogel displayed cell-responsive degradation and resulted in increased DNA, GAG, and collagen accumulation compared with other hydrogels. This study demonstrates that integrin-mediated interactions within CS microenvironment provide an optimal hydrogel scaffold for cartilage tissue engineering application. PMID:25266634

Engineering three-dimensional cell mechanical microenvironment with hydrogels.

PubMed

Huang, Guoyou; Wang, Lin; Wang, Shuqi; Han, Yulong; Wu, Jinhui; Zhang, Qiancheng; Xu, Feng; Lu, Tian Jian

2012-12-01

Cell mechanical microenvironment (CMM) significantly affects cell behaviors such as spreading, migration, proliferation and differentiation. However, most studies on cell response to mechanical stimulation are based on two-dimensional (2D) planar substrates, which cannot mimic native three-dimensional (3D) CMM. Accumulating evidence has shown that there is a significant difference in cell behavior in 2D and 3D microenvironments. Among the materials used for engineering 3D CMM, hydrogels have gained increasing attention due to their tunable properties (e.g. chemical and mechanical properties). In this paper, we provide an overview of recent advances in engineering hydrogel-based 3D CMM. Effects of mechanical cues (e.g. hydrogel stiffness and externally induced stress/strain in hydrogels) on cell behaviors are described. A variety of approaches to load mechanical stimuli in 3D hydrogel-based constructs are also discussed.

Designer bFGF-incorporated d-form self-assembly peptide nanofiber scaffolds to promote bone repair.

PubMed

He, Bin; Ou, Yunsheng; Chen, Shuo; Zhao, Weikang; Zhou, Ao; Zhao, Jinqiu; Li, Hong; Jiang, Dianming; Zhu, Yong

2017-05-01

d-Form and l-form peptide nanofiber scaffolds can spontaneously form stable β-sheet secondary structures and nanofiber hydrogel scaffolds, and hold some promise in hemostasis and wound healing. We report here on the synthetic self-assembling peptide d-RADA16 and l-RADA16 are both found to produce stable β-sheet secondary structure and nanofiber hydrogel scaffolds based on circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM) and rheology analysis etc. d-RADA16 hydrogel and l-RADA16 hydrogel can enhance obvious bone repair in femoral condyle defects of the Sprague-Dawley (SD) rat model compared to PBS treatment. Based on micro-computed tomography (CT), it was revealed that d-RADA16 hydrogel and l-RADA16 hydrogel were capable to obtain the extensive bone healing. Histological evaluation also found that these two hydrogels facilitate the presence of more mature bone tissue within the femoral condyle defects. Additionally, d-RADA16 hydrogel showed some potential in storing and releasing basic-fibroblast growth factor (bFGF) which was able to further promote bone regeneration based on micro-CT analysis. These results indicate that d-form peptide nanofiber hydrogel have some special capacity for bone repair. Copyright © 2016 Elsevier B.V. All rights reserved.

Impact of RGD amount in dextran-based hydrogels for cell delivery.

PubMed

Riahi, Nesrine; Liberelle, Benoît; Henry, Olivier; De Crescenzo, Gregory

2017-04-01

Dextran is one of the hydrophilic polymers that is used for hydrogel preparation. As any polysaccharide, it presents a high density of hydroxyl groups, which make possible several types of derivatization and crosslinking reactions. Furthermore, dextran is an excellent candidate for hydrogel fabrication with controlled cell/scaffold interactions as it is resistant to protein adsorption and cell adhesion. RGD peptide can be grafted to the dextran in order to promote selected cell adhesion and proliferation. Altogether, we have developed a novel strategy to graft the RGD peptide sequence to dextran-based hydrogel using divinyl sulfone as a linker. The resulting RGD functionalized dextran-based hydrogels were transparent, presented a smooth surface and were easy to handle. The impact of varying RGD peptide amounts, hydrogel porosity and topology upon human umbilical vein endothelial cell (HUVEC) adhesion, proliferation and infiltration was investigated. Our results demonstrated that 0.1% of RGD-modified dextran within the gel was sufficient to support HUVEC cells adhesion to the hydrogel surface. Sodium chloride was added (i) to the original hydrogel mix in order to form a macroporous structure presenting interconnected pores and (ii) to the hydrogel surface to create small orifices essential for cells migration inside the matrix. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation of wheat straw based superabsorbent resins and their applications as adsorbents for ammonium and phosphate removal.

PubMed

Liu, Jia; Su, Yuan; Li, Qian; Yue, Qinyan; Gao, Baoyu

2013-09-01

A novel wheat straw cellulose-g-poly (potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin (SAR) was prepared by graft copolymerization. The structure and performance of the WSC-g-PKA/PVA semi-IPNs SAR was studied and compared with those of wheat straw cellulose-g-poly (potassium acrylate) (WSC-g-PKA) SAR. The effects of various experimental parameters such as solution pH, concentration, contact time and ion strength on NH4(+) and PO4(3-) removal from solutions were investigated. Equilibrium isotherm data of adsorption of both NH4(+) and PO4(3-) were well fitted to the Freundlich model. Kinetic analysis showed that the pseudo-second-order kinetic model was more suitable for describing the whole adsorption process of NH4(+) and PO4(3-) on SARs. Overall, WSC-g-PKA/PVA semi-IPNs SAR showed better properties in comparison with WSC-g-PKA SAR and it could be considered as one efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cationic hemicellulose-based hydrogels for arsenic and chromium removal from aqueous solutions.

PubMed

Dax, Daniel; Chávez, María Soledad; Xu, Chunlin; Willför, Stefan; Mendonça, Regis Teixeira; Sánchez, Julio

2014-10-13

In this work the synthesis of hemicellulose-based hydrogels and their application for the removal of arsenic and chromium ions is described. In a first step O-acetyl galactoglucomannan (GGM) was subjected to a transesterification applying glycidyl methacrylate (GMA) for the synthesis of novel GGM macromonomers. Two distinguished and purified GGM fractions with molar mass of 7.1 and 28 kDa were used as starting materials. The resulting GGM macromonomers (GGM-MA) contained well-defined amounts of methacrylate groups as determined by (1)H NMR spectroscopy. Selected GGM-MA derivatives were consecutively applied as a crosslinker in the synthesis of tailored hydrogels using [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MeDMA) as monomer. The swelling rate of the hydrogels was determined and the coherence between the swelling rate and the hydrogel composition was examined. The morphology of the GGM-based hydrogels was analysed by SEM and the hydrogels revealed a high surface area and were assessed in respect to their ability to remove arsenate and chromate ions from aqueous solutions. The presented bio-based hydrogels are of high interest especially for the mining industries as a sustainable material for the treatment of their highly contaminated wastewaters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reduced Graphene Oxide-Based Silver Nanoparticle-Containing Composite Hydrogel as Highly Efficient Dye Catalysts for Wastewater Treatment

PubMed Central

Jiao, Tifeng; Guo, Haiying; Zhang, Qingrui; Peng, Qiuming; Tang, Yongfu; Yan, Xuehai; Li, Bingbing

2015-01-01

New reduced graphene oxide-based silver nanoparticle-containing composite hydrogels were successfully prepared in situ through the simultaneous reduction of GO and noble metal precursors within the GO gel matrix. The as-formed hydrogels are composed of a network structure of cross-linked nanosheets. The reported method is based on the in situ co-reduction of GO and silver acetate within the hydrogel matrix to form RGO-based composite gel. The stabilization of silver nanoparticles was also achieved simultaneously within the gel composite system. The as-formed silver nanoparticles were found to be homogeneously and uniformly dispersed on the surface of the RGO nanosheets within the composite gel. More importantly, this RGO-based silver nanoparticle-containing composite hydrogel matrix acts as a potential catalyst for removing organic dye pollutants from an aqueous environment. Interestingly, the as-prepared catalytic composite matrix structure can be conveniently separated from an aqueous environment after the reaction, suggesting the potentially large-scale applications of the reduced graphene oxide-based nanoparticle-containing composite hydrogels for organic dye removal and wastewater treatment. PMID:26183266

Cross-Linked Hydrogel for Pharmaceutical Applications: A Review

PubMed Central

2017-01-01

Hydrogels are promising biomaterials because of their important qualities such as biocompatibility, biodegradability, hydrophilicity and non-toxicity. These qualities make hydrogels suitable for application in medical and pharmaceutical field. Recently, a tremendous growth of hydrogel application is seen, especially as gel and patch form, in transdermal drug delivery. This review mainly focuses on the types of hydrogels based on cross-linking and; secondly to describe the possible synthesis methods to design hydrogels for different pharmaceutical applications. The synthesis and chemistry of these hydrogels are discussed using specific pharmaceutical examples. The structure and water content in a typical hydrogel have also been discussed. PMID:29399542

Water-soluble, neutral 3,5-diformyl-BODIPY with extended fluorescence lifetime in a self-healable chitosan hydrogel.

PubMed

Belali, Simin; Emandi, Ganapathi; Cafolla, Atillio A; O'Connell, Barry; Haffner, Benjamin; Möbius, Matthias E; Karimi, Alireza; Senge, Mathias O

2017-11-08

3,5-Diformyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (3,5-diformyl-BODIPY) can be used as an efficient biofunctional cross-linker to generate a new class of chitosan-based hydrogels with fluorescence resonance energy transfer (FRET) dynamics and good solubility in water. The hydrogel was fully characterized by FT-IR, UV-vis, fluorescence, FE-SEM, AFM, rheology and picosecond time-resolved spectroscopic techniques. The self-healing ability was demonstrated by rheological recovery and macroscopic and microscopic observations. The fluorescence lifetime was found to increase in aqueous solution of the BODIPY-chitosan hydrogel compared to the 3,5-diformyl-BODIPY monomer. Calculations based on experimental results such as red-shift and decreased intensity of the emission spectrum of highly dye-concentrated hydrogel in comparison to dilute hydrogels, together with changes in the fluorescence lifetime of the hydrogel at different concentration of dyes, suggest that the BDP-CS hydrogels fluorescence dynamics obey the Förster resonance energy transfer (FRET). Improvements in mechanical and photochemical properties and the acceptable values of BODIPY fluorescence lifetime in the hydrogel matrix indicate the utility of the newly synthesized hydrogels for biomedical applications.

Thermoresponsive, in situ crosslinkable hydrogels based on N-isopropylacrylamide: Fabrication, characterization and mesenchymal stem cell encapsulation

PubMed Central

Klouda, Leda; Perkins, Kevin R.; Watson, Brendan M.; Hacker, Michael C.; Bryant, Stephanie J.; Raphael, Robert M.; Kasper, F. Kurtis; Mikos, Antonios G.

2011-01-01

Hydrogels that solidify in response to a dual, physical and chemical, mechanism upon temperature increase were fabricated and characterized. The hydrogels were based on N-isopropylacrylamide, which renders them thermoresponsive, and contained covalently crosslinkable moieties in the macromers. The effects of the macromer end group, namely acrylate or methacrylate, and the fabrication conditions were investigated on the degradative and swelling properties of the hydrogels. The hydrogels exhibited higher swelling below their lower critical solution temperature (LCST). When immersed in cell culture media at physiological temperature, which was above their LCST, hydrogels showed constant swelling and no degradation over eight weeks, with methacrylated hydrogels having higher swelling than their acrylated analogs. In addition, hydrogels immersed in cell culture media under the same conditions showed lower swelling as compared to phosphate buffered saline. The interplay between chemical crosslinking and thermally induced phase separation affected the swelling characteristics of hydrogels in different media. Mesenchymal stem cells encapsulated in the hydrogels in vitro were viable over three weeks and markers of osteogenic differentiation were detected when the cells were cultured with osteogenic supplements. Hydrogel mineralization in the absence of cells was observed in cell culture medium with the addition of fetal bovine serum and β-glycerol phosphate. The results suggest that these hydrogels may be suitable as carriers for cell delivery in tissue engineering. PMID:21187170

Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture.

PubMed

Li, Yongsan; Zhang, Yaling; Wei, Yen; Tao, Lei

2017-09-29

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is prepared by mixing solutions of glycol chitosan with a synthesized benzaldehyde terminated polymer gelator, and hydrogels are efficiently obtained in several minutes at room temperature. By varying ratios between glycol chitosan, polymer gelator, and water contents, versatile hydrogels with different gelation times and stiffness are obtained. When damaged, the hydrogel can recover its appearances and modulus, due to the reversibility of the dynamic imine bonds as crosslinkages. This self-healable property enables the hydrogel to be injectable since it can be self-healed from squeezed pieces to an integral bulk hydrogel after the injection process. The hydrogel is also multi-responsive to many bio-active stimuli due to different equilibration statuses of the dynamic imine bonds. This hydrogel was confirmed as bio-compatible, and L929 mouse fibroblast cells were embedded following standard procedures and the cell proliferation was easily assessed by a 3D cell cultivation process. The hydrogel can offer an adjustable platform for different research where a physiological mimic of a 3D environment for cells is profited. Along with its multi-responsive, self-healable, and injectable properties, the hydrogels can potentially be applied as multiple carriers for drugs and cells in future bio-medical applications.

Gelatin- and starch-based hydrogels. Part B: In vitro mesenchymal stem cell behavior on the hydrogels.

PubMed

Van Nieuwenhove, Ine; Salamon, Achim; Adam, Stefanie; Dubruel, Peter; Van Vlierberghe, Sandra; Peters, Kirsten

2017-04-01

Tissue regeneration often occurs only to a limited extent. By providing a three-dimensional matrix serving as a surrogate extracellular matrix that promotes adult stem cell adhesion, proliferation and differentiation, scaffold-guided tissue regeneration aims at overcoming this limitation. In this study, we applied hydrogels made from crosslinkable gelatin, the hydrolyzed form of collagen, and functionalized starch which were characterized in depth and optimized as described in Van Nieuwenhove et al., 2016. "Gelatin- and Starch-Based Hydrogels. Part A: Hydrogel Development, Characterization and Coating", Carbohydrate Polymers 152:129-39. Collagen is the main structural protein in animal connective tissue and the most abundant protein in mammals. Starch is a carbohydrate consisting of a mixture of amylose and amylopectin. Hydrogels were developed with varying chemical composition (ratio of starch to gelatin applied) and different degrees of methacrylation of the applied gelatin phase. The hydrogels used exhibited no adverse effect on viability of the stem cells cultured on them. Moreover, initial cell adhesion did not differ significantly between them, while the strongest proliferation was observed on the hydrogel with the highest degree of cross-linking. On the least crosslinked and thus most flexible hydrogels, the highest degree of adipogenic differentiation was found, while osteogenic differentiation was the strongest on the most rigid, starch-blended hydrogels. Hydrogel coating with extracellular matrix compounds aggrecan or fibronectin prior to cell seeding exhibited no significant effects. Thus, gelatin-based hydrogels can be optimized regarding maximum promotion of either adipogenic or osteogenic stem cell differentiation in vitro, which makes them promising candidates for in vivo evaluation in clinical studies aiming at either soft or hard tissue regeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogel microparticles for biosensing

PubMed Central

Le Goff, Gaelle C.; Srinivas, Rathi L.; Hill, W. Adam; Doyle, Patrick S.

2015-01-01

Due to their hydrophilic, biocompatible, and highly tunable nature, hydrogel materials have attracted strong interest in the recent years for numerous biotechnological applications. In particular, their solution-like environment and non-fouling nature in complex biological samples render hydrogels as ideal substrates for biosensing applications. Hydrogel coatings, and later, gel dot surface microarrays, were successfully used in sensitive nucleic acid assays and immunoassays. More recently, new microfabrication techniques for synthesizing encoded particles from hydrogel materials have enabled the development of hydrogel-based suspension arrays. Lithography processes and droplet-based microfluidic techniques enable generation of libraries of particles with unique spectral or graphical codes, for multiplexed sensing in biological samples. In this review, we discuss the key questions arising when designing hydrogel particles dedicated to biosensing. How can the hydrogel material be engineered in order to tune its properties and immobilize bioprobes inside? What are the strategies to fabricate and encode gel particles, and how can particles be processed and decoded after the assay? Finally, we review the bioassays reported so far in the literature that have used hydrogel particle arrays and give an outlook of further developments of the field. PMID:26594056

Poly(ethylene glycol) (PEG)-lactic acid nanocarrier-based degradable hydrogels for restoring the vaginal microenvironment

PubMed Central

Rajan, Sujata Sundara; Turovskiy, Yevgeniy; Singh, Yashveer; Chikindas, Michael L.; Sinko, Patrick J.

2014-01-01

Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH 7.4) and acetate buffer (AB, pH 4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%–14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV. PMID:25223229

Biodegradation of PVP-CMC hydrogel film: a useful food packaging material.

PubMed

Roy, Niladri; Saha, Nabanita; Kitano, Takeshi; Saha, Petr

2012-06-20

Hydrogels can offer new opportunities for the design of efficient packaging materials with desirable properties (i.e. durability, biodegradability and mechanical strength). It is a promising and emerging concept, as most of the biopolymer based hydrogels are supposed to be biodegradable, they can be considered as alternative eco-friendly packaging materials. This article reports about synthetic (polyvinylpyrrolidone (PVP)) and biopolymer (carboxymethyl cellulose (CMC)) based a novel hydrogel film and its nature of biodegradability under controlled environmental condition. The dry hydrogel films were prepared by solution casting method and designated as 'PVP-CMC hydrogel films'. The hydrogel film containing PVP and CMC in a ratio of 20:80 shows best mechanical properties among all the test samples (i.e. 10:90, 20:80, 50:50, 80:20 and 90:10). Thus, PVP-CMC hydrogel film of 20:80 was considered as a useful food packaging material and further experiments were carried out with this particular hydrogel film. Biodegradation of the PVP-CMC hydrogel films were studied in liquid state (Czapec-Dox liquid medium+soil extracts) until 8 weeks. Variation in mechanical, viscoelastic properties and weight loss of the hydrogel films with time provide the direct evidence of biodegradation of the hydrogels. About 38% weight loss was observed within 8 weeks. FTIR spectra of the hydrogel films (before and after biodegradation) show shifts of the peaks and also change in the peak intensities, which refer to the physico-chemical change in the hydrogel structure and SEM views of the hydrogels show how internal structure of the PVP-CMC film changes in the course of biodegradation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Hydrogel based QCM aptasensor for detection of avian influenza virus.

PubMed

Wang, Ronghui; Li, Yanbin

2013-04-15

The objective of this study was to develop a quartz crystal microbalance (QCM) aptasensor based on ssDNA crosslinked polymeric hydrogel for rapid, sensitive and specific detection of avian influenza virus (AIV) H5N1. A selected aptamer with high affinity and specificity against AIV H5N1 surface protein was used, and hybridization between the aptamer and ssDNA formed the crosslinker in the polymer hydrogel. The aptamer hydrogel was immobilized on the gold surface of QCM sensor using a self-assembled monolayer method. The hydrogel remained in the state of shrink if no H5N1 virus was present in the sample because of the crosslinking between the aptamer and ssDNA in the polymer network. When it exposed to target virus, the binding reaction between the aptamer and H5N1 virus caused the dissolution of the linkage between the aptamer and ssDNA, resulting in the abrupt swelling of the hydrogel. The swollen hydrogel was monitored by the QCM sensor in terms of decreased frequency. Three polymeric hydrogels with different ratio (100:1 hydrogel I, 10:1 hydrogel II, 1:1 hydrogel III) of acrylamide and the aptamer monomer were synthesized, respectively, and then were used as the QCM sensor coating material. The results showed that the developed hydrogel QCM aptasensor was capable of detecting target H5N1 virus, and among the three developed aptamer hydrogels, hydrogel III coated QCM aptasensor achieved the highest sensitivity with the detection limit of 0.0128 HAU (HA unit). The total detection time from sampling to detection was only 30 min. In comparison with the anti-H5 antibody coated QCM immunosensor, the hydrogel QCM aptasensor lowered the detection limit and reduced the detection time. Copyright © 2012 Elsevier B.V. All rights reserved.

Gelator-polysaccharide hybrid hydrogel for selective and controllable dye release.

PubMed

Li, Ping; Dou, Xiao-Qiu; Tang, Yi-Tian; Zhu, Shenmin; Gu, Jiajun; Feng, Chuan-Liang; Zhang, Di

2012-12-01

In this paper, 1,4-bi(phenylalanine-diglycol)-benzene (PDB) based Low-Molecular-Weight-Gelator (LMWG) hydrogels are modified using hydrophilic polysaccharide (sodium alginate). A set of techniques including Fourier transform infrared (FT-IR) spectroscopy, (1)H Nuclear Magnetic Resonance ((1)H NMR), X-ray powder diffraction (XRD), Ultraviolet-Visible (UV-Vis), and circular dichroism (CD) had confirmed a β-turn arrangement of PDB gelators and a semi-interpenetrating network (semi-IPN), which was formed through hydrogen bonds between LMWG fibers and polysaccharide chains. The evaluation of physicochemical properties of hydrogels indicates that gelator-polysaccharide hybrid hydrogels possess better mechanical and water retention properties than LMWG hydrogels. The release study of dyes (model drug) from both LMWG and hybrid hydrogels was carried out. Compared with PDB based hydrogels, hybrid hydrogels show a selective and controllable release property for certain dyes. The results suggest LMWG-polysaccharide hybrid gels may find potential applications as promising drug delivery vehicles for drug molecules. Copyright © 2012 Elsevier Inc. All rights reserved.

Development and characterization of novel alginate-based hydrogels as vehicles for bone substitutes.

PubMed

Morais, D S; Rodrigues, M A; Silva, T I; Lopes, M A; Santos, M; Santos, J D; Botelho, C M

2013-06-05

In this work three different hydrogels were developed to associate, as vehicles, with the synthetic bone substitute GR-HAP. One based on an alginate matrix (Alg); a second on a mixture of alginate and chitosan (Alg/Ch); and a third on alginate and hyaluronate (Alg/HA), using Ca(2+) ions as cross-linking agents. The hydrogels, as well as the respective injectable bone substitutes (IBSs), were fully characterized from the physical-chemical point of view. Weight change studies proved that all hydrogels were able to swell and degrade within 72 h at pH 7.4 and 4.0, being Alg/HA the hydrogel with the highest degradation rate (80%). Rheology studies demonstrated that all hydrogels are non-Newtonian viscoelastic fluids, and injectability tests showed that IBSs presented low maximum extrusion forces, as well as quite stable average forces. In conclusion, the studied hydrogels present the necessary features to be successfully used as vehicles of GR-HAP, particularly the hydrogel Alg/HA. Copyright © 2013 Elsevier Ltd. All rights reserved.

Introduction to cell–hydrogel mechanosensing

PubMed Central

Ahearne, Mark

2014-01-01

The development of hydrogel-based biomaterials represents a promising approach to generating new strategies for tissue engineering and regenerative medicine. In order to develop more sophisticated cell-seeded hydrogel constructs, it is important to understand how cells mechanically interact with hydrogels. In this paper, we review the mechanisms by which cells remodel hydrogels, the influence that the hydrogel mechanical and structural properties have on cell behaviour and the role of mechanical stimulation in cell-seeded hydrogels. Cell-mediated remodelling of hydrogels is directed by several cellular processes, including adhesion, migration, contraction, degradation and extracellular matrix deposition. Variations in hydrogel stiffness, density, composition, orientation and viscoelastic characteristics all affect cell activity and phenotype. The application of mechanical force on cells encapsulated in hydrogels can also instigate changes in cell behaviour. By improving our understanding of cell–material mechano-interactions in hydrogels, this should enable a new generation of regenerative medical therapies to be developed. PMID:24748951

Light-guiding hydrogels for cell-based sensing and optogenetic synthesis in vivo

NASA Astrophysics Data System (ADS)

Choi, Myunghwan; Choi, Jin Woo; Kim, Seonghoon; Nizamoglu, Sedat; Hahn, Sei Kwang; Yun, Seok Hyun

2013-12-01

Polymer hydrogels are widely used as cell scaffolds for biomedical applications. Although the biochemical and biophysical properties of hydrogels have been investigated extensively, little attention has been paid to their potential photonic functionalities. Here, we report cell-integrated polyethylene glycol-based hydrogels for in vivo optical-sensing and therapy applications. Hydrogel patches containing cells were implanted in awake, freely moving mice for several days and shown to offer long-term transparency, biocompatibility, cell viability and light-guiding properties (loss of <1 dB cm-1). Using optogenetic, glucagon-like peptide-1 secreting cells, we conducted light-controlled therapy using the hydrogel in a mouse model with diabetes and obtained improved glucose homeostasis. Furthermore, real-time optical readout of encapsulated heat-shock-protein-coupled fluorescent reporter cells made it possible to measure the nanotoxicity of cadmium-based bare and shelled quantum dots (CdTe; CdSe/ZnS) in vivo.

Thin Hydrogel Films for Optical Biosensor Applications

PubMed Central

Mateescu, Anca; Wang, Yi; Dostalek, Jakub; Jonas, Ulrich

2012-01-01

Hydrogel materials consisting of water-swollen polymer networks exhibit a large number of specific properties highly attractive for a variety of optical biosensor applications. This properties profile embraces the aqueous swelling medium as the basis of biocompatibility, non-fouling behavior, and being not cell toxic, while providing high optical quality and transparency. The present review focuses on some of the most interesting aspects of surface-attached hydrogel films as active binding matrices in optical biosensors based on surface plasmon resonance and optical waveguide mode spectroscopy. In particular, the chemical nature, specific properties, and applications of such hydrogel surface architectures for highly sensitive affinity biosensors based on evanescent wave optics are discussed. The specific class of responsive hydrogel systems, which can change their physical state in response to externally applied stimuli, have found large interest as sophisticated materials that provide a complex behavior to hydrogel-based sensing devices. PMID:24957962

Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio-Inspired Materials for "Mineral Plastics".

PubMed

Sun, Shengtong; Mao, Li-Bo; Lei, Zhouyue; Yu, Shu-Hong; Cölfen, Helmut

2016-09-19

Given increasing environmental issues due to the large usage of non-biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio-inspired synthesis of mineral-based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)-based hydrogel consisting of very small ACC nanoparticles physically cross-linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self-healable. Upon drying, the hydrogel forms free-standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the "mineral plastics". © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of immobilizing of low molecular weight hyaluronic acid within gelatin-based hydrogel through enzymatic reaction on behavior of enclosed endothelial cells.

PubMed

Khanmohammadi, Mehdi; Sakai, Shinji; Taya, Masahito

2017-04-01

The hydrogels having the ability to promote migration and morphogenesis of endothelial cells (ECs) are useful for fabricating vascularized dense tissues in vitro. The present study explores the immobilization of low molecular weight hyaluronic acid (LMWHA) derivative within gelatin-based hydrogel to stimulate migration of ECs. The LMWHA derivative possessing phenolic hydroxyl moieties (LMWHA-Ph) was bound to gelatin-based derivative hydrogel through the horseradish peroxidase-catalyzed reaction. The motility of ECs was analyzed by scratch migration assay and microparticle-based cell migration assay. The incorporated LMWHA-Ph molecules within hydrogel was found to be preserved stably through covalent bonds during incubation. The free and immobilized LMWHA-Ph did not lose an inherent stimulatory effect on human umbilical vein endothelial cells (HUVECs). The immobilized LMWHA-Ph within gelatin-based hydrogel induced the high motility of HUVECs, accompanied by robust cytoskeleton extension, and cell subpopulation expressing CD44 cell receptor. In the presence of immobilized LMWHA-Ph, the migration distance and the number of existing HUVECs were demonstrated to be encouraged in dose-dependent and time-dependent manners. Based on the results obtained in this work, it was concluded that the enzymatic immobilization of LMWHA-Ph within gelatin-based hydrogel represents a promising approach to promote ECs' motility and further exploitation for vascular tissue engineering applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Gellan gum-based hydrogels for intervertebral disc tissue-engineering applications.

PubMed

Silva-Correia, J; Oliveira, J M; Caridade, S G; Oliveira, J T; Sousa, R A; Mano, J F; Reis, R L

2011-06-01

Intervertebral disc (IVD) degeneration is a challenging clinical problem that urgently demands viable nucleus pulposus (NP) implant materials. The best suited biomaterial for NP regeneration has yet to be identified, but it is believed that biodegradable hydrogel-based materials are promising candidates. In this work, we have developed ionic- and photo-crosslinked methacrylated gellan gum (GG-MA) hydrogels to be used in acellular and cellular tissue-engineering strategies for the regeneration of IVDs. The physicochemical properties of the developed hydrogels were investigated by Fourier-transform infrared spectroscopy, (1) H nuclear magnetic resonance and differential scanning calorimetry. The swelling ability and degradation rate of hydrogels were also analysed in phosphate-buffered saline solution at physiological pH for a period of 30 days. Additionally, the morphology and mechanical properties of the hydrogels were assessed under a scanning electron microscope and dynamic compression, respectively. An in vitro study was carried out to screen possible cytotoxicity of the gellan gum-based hydrogels by culturing rat lung fibroblasts (L929 cells) with hydrogel leachables up to 7 days. The results demonstrated that gellan gum was successfully methacrylated. We observed that the produced GG-MA hydrogels possess improved mechanical properties and lower water uptake ability and degradation rate as compared to gellan gum. This work also revealed that GG-MA hydrogels are non-cytotoxic in vitro, thus being promising biomaterials to be used in IVD tissue-engineering strategies. Copyright © 2010 John Wiley & Sons, Ltd.

Hydrogels for Hydrophobic Drug Delivery. Classification, Synthesis and Applications

PubMed Central

Stewart, Sarah; Ervine, Michael; Al-Kasasbeh, Rehan; Donnelly, Ryan F.

2018-01-01

Hydrogels have been shown to be very useful in the field of drug delivery due to their high biocompatibility and ability to sustain delivery. Therefore, the tuning of their properties should be the focus of study to optimise their potential. Hydrogels have been generally limited to the delivery of hydrophilic drugs. However, as many of the new drugs coming to market are hydrophobic in nature, new approaches for integrating hydrophobic drugs into hydrogels should be developed. This article discusses the possible new ways to incorporate hydrophobic drugs within hydrogel structures that have been developed through research. This review describes hydrogel-based systems for hydrophobic compound delivery included in the literature. The section covers all the main types of hydrogels, including physical hydrogels and chemical hydrogels. Additionally, reported applications of these hydrogels are described in the subsequent sections. PMID:29364833

Menstrual blood loss measurement: validation of the alkaline hematin technique for feminine hygiene products containing superabsorbent polymers.

PubMed

Magnay, Julia L; Nevatte, Tracy M; Dhingra, Vandana; O'Brien, Shaughn

2010-12-01

To validate the alkaline hematin technique for measurement of menstrual blood loss using ultra-thin sanitary towels that contain superabsorbent polymer granules as the absorptive agent. Laboratory study using simulated menstrual fluid (SMF) and Always Ultra Normal, Long, and Night "with wings" sanitary towels. Keele Menstrual Disorders Laboratory. None. None. Recovery of blood, linearity, and interassay variation over a range of SMF volumes applied to towels. Because of the variable percentage of blood in menstrual fluid, blood recovery was assessed from SMF constituted as 10%, 25%, 50%, and 100% blood. The lower limit of reliable detection and the effect of storing soiled towels for up to 4 weeks at 15°C-20°C, 4°C, and -20°C before analysis were determined. Ninety percent recovery was reproducibly achieved up to 30 mL applied volume at all tested SMF compositions, except at low volume or high dilution equivalent to <2 mL whole blood. Samples could be stored for 3 weeks at all tested temperatures without loss of recovery. The technique was suitable for processing towels individually or in batches. The alkaline hematin technique is a suitable and validated method for measuring menstrual blood loss from Always Ultra sanitary towels that contain superabsorbent polymers. Copyright © 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

In vitro BMP-2 peptide release from thiolated chitosan based hydrogel.

PubMed

Liu, Xujie; Yu, Bo; Huang, Qianli; Liu, Rui; Feng, Qingling; Cai, Qiang; Mi, Shengli

2016-12-01

Thiolated chitosan based thermo-sensitive hydrogel is a water soluble system and the existing thiol groups are beneficial for the delivery of cysteine-rich peptides. In the present study, a kind of thiolated chitosan, i.e. chitosan-4-thio-butylamidine (CS-TBA) conjugate was characterized and used to prepare CS-TBA/hydroxyapatite (HA)/beta-glycerophosphate disodium (β-GP) thermo-sensitive hydrogel. The cysteine terminated peptide 24 (P24) containing residues 73-92 of the knuckle epitope of BMP-2 (N→C: KIPKASSVPTELSAISTLYLSGGC) was synthesized and characterized. The release behavior of P24 from CS-TBA based hydrogel was investigated in vitro. The thiol groups in CS-TBA may react with thiol groups in P24, thus decreases the P24 release rate and maintains the peptide release for a longer time compared with unmodified chitosan based hydrogel. Moreover, the bioactivity of P24 is preserved during release process. These results indicate that P24 loaded CS-TBA based thermosensitive hydrogel is a potential material for minimally invasive surgery of bone repair. Copyright © 2016 Elsevier B.V. All rights reserved.

Automation of 3D cell culture using chemically defined hydrogels.

PubMed

Rimann, Markus; Angres, Brigitte; Patocchi-Tenzer, Isabel; Braum, Susanne; Graf-Hausner, Ursula

2014-04-01

Drug development relies on high-throughput screening involving cell-based assays. Most of the assays are still based on cells grown in monolayer rather than in three-dimensional (3D) formats, although cells behave more in vivo-like in 3D. To exemplify the adoption of 3D techniques in drug development, this project investigated the automation of a hydrogel-based 3D cell culture system using a liquid-handling robot. The hydrogel technology used offers high flexibility of gel design due to a modular composition of a polymer network and bioactive components. The cell inert degradation of the gel at the end of the culture period guaranteed the harmless isolation of live cells for further downstream processing. Human colon carcinoma cells HCT-116 were encapsulated and grown in these dextran-based hydrogels, thereby forming 3D multicellular spheroids. Viability and DNA content of the cells were shown to be similar in automated and manually produced hydrogels. Furthermore, cell treatment with toxic Taxol concentrations (100 nM) had the same effect on HCT-116 cell viability in manually and automated hydrogel preparations. Finally, a fully automated dose-response curve with the reference compound Taxol showed the potential of this hydrogel-based 3D cell culture system in advanced drug development.

Hydrogel-Based Drug Delivery Systems for Poorly Water-Soluble Drugs.

PubMed

McKenzie, Matthew; Betts, David; Suh, Amy; Bui, Kathryn; Kim, London Doyoung; Cho, Hyunah

2015-11-13

Hydrogels are three-dimensional materials that can withstand a great amount of water incorporation while maintaining integrity. This allows hydrogels to be very unique biomedical materials, especially for drug delivery. Much effort has been made to incorporate hydrophilic molecules in hydrogels in the field of drug delivery, while loading of hydrophobic drugs has not been vastly studied. However, in recent years, research has also been conducted on incorporating hydrophobic molecules within hydrogel matrices for achieving a steady release of drugs to treat various ailments. Here, we summarize the types of hydrogels used as drug delivery vehicles, various methods to incorporate hydrophobic molecules in hydrogel matrices, and the potential therapeutic applications of hydrogels in cancer.

Formulation and evaluation of microemulsion-based hydrogel for topical delivery.

PubMed

Sabale, Vidya; Vora, Sejal

2012-07-01

The purpose of this study was to develop microemulsion-based hydrogel formulation for topical delivery of bifonazole with an objective to increase the solubility and skin permeability of the drug. Oleic acid was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems. The pseudo-ternary phase diagrams for microemulsion regions were constructed using oleic acid as the oil, Tween 80 as the surfactant and isopropyl alcohol (IPA) as the cosurfactant. Various microemulsion formulations were prepared and optimized by 3(2) factorial design on the basis of percentage (%) transmittance, globule size, zeta potential, drug release, and skin permeability. The abilities of various microemulsions to deliver bifonazole through the skin were evaluated ex vivo using Franz diffusion cells fitted with rat skins. The Hydroxy Propyl Methyl Cellulose (HPMC) K100 M as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The optimized microemulsion-based hydrogel was evaluated for viscosity, spreadability, skin irritancy, skin permeability, stability, and antifungal activity by comparing it with marketed bifonazole cream. The mechanism of drug release from microemulsion-based hydrogel was observed to follow zero order kinetics. The studied optimized microemulsion-based hydrogel showed a good stability over the period of 3 months. Average globule size of optimized microemulsion (F5) was found to be 18.98 nm, zeta potential was found to be -5.56 mv, and permeability of drug from microemulsion within 8 h was observed 84%. The antifungal activity of microemulsion-based hydrogel was found to be comparable with marketed cream. The results indicate that the studied microemulsion-based hydrogel (F5) has a potential for sustained action of drug release and it may act as promising vehicle for topical delivery of ibuprofen.

Biofunctionalized peptide-based hydrogels provide permissive scaffolds to attract neurite outgrowth from spiral ganglion neurons.

PubMed

Frick, Claudia; Müller, Marcus; Wank, Ute; Tropitzsch, Anke; Kramer, Benedikt; Senn, Pascal; Rask-Andersen, Helge; Wiesmüller, Karl-Heinz; Löwenheim, Hubert

2017-01-01

Cochlear implants (CI) allow for hearing rehabilitation in patients with sensorineural hearing loss or deafness. Restricted CI performance results from the spatial gap between spiral ganglion neurons and the CI, causing current spread that limits spatially restricted stimulation and impairs frequency resolution. This may be substantially improved by guiding peripheral processes of spiral ganglion neurons towards and onto the CI electrode contacts. An injectable, peptide-based hydrogel was developed which may provide a permissive scaffold to facilitate neurite growth towards the CI. To test hydrogel capacity to attract spiral ganglion neurites, neurite outgrowth was quantified in an in vitro model using a custom-designed hydrogel scaffold and PuraMatrix ® . Neurite attachment to native hydrogels is poor, but significantly improved by incorporation of brain-derived neurotrophic factor (BDNF), covalent coupling of the bioactive laminin epitope IKVAV and the incorporation a full length laminin to hydrogel scaffolds. Incorporation of full length laminin protein into a novel custom-designed biofunctionalized hydrogel (IKVAV-GGG-SIINFEKL) allows for neurite outgrowth into the hydrogel scaffold. The study demonstrates that peptide-based hydrogels can be specifically biofunctionalized to provide a permissive scaffold to attract neurite outgrowth from spiral ganglion neurons. Such biomaterials appear suitable to bridge the spatial gap between neurons and the CI. Copyright © 2016 Elsevier B.V. All rights reserved.

Advances in Carbon Nanotubes-Hydrogel Hybrids in Nanomedicine for Therapeutics.

PubMed

Vashist, Arti; Kaushik, Ajeet; Vashist, Atul; Sagar, Vidya; Ghosal, Anujit; Gupta, Y K; Ahmad, Sharif; Nair, Madhavan

2018-05-01

In spite of significant advancement in hydrogel technology, low mechanical strength and lack of electrical conductivity have limited their next-level biomedical applications for skeletal muscles, cardiac and neural cells. Host-guest chemistry based hybrid nanocomposites systems have gained attention as they completely overcome these pitfalls and generate bioscaffolds with tunable electrical and mechanical characteristics. In recent years, carbon nanotube (CNT)-based hybrid hydrogels have emerged as innovative candidates with diverse applications in regenerative medicines, tissue engineering, drug delivery devices, implantable devices, biosensing, and biorobotics. This article is an attempt to recapitulate the advancement in synthesis and characterization of hybrid hydrogels and provide deep insights toward their functioning and success as biomedical devices. The improved comparative performance and biocompatibility of CNT-hydrogels hybrids systems developed for targeted biomedical applications are addressed here. Recent updates toward diverse applications and limitations of CNT hybrid hydrogels is the strength of the review. This will provide a holistic approach toward understanding of CNT-based hydrogels and their applications in nanotheranostics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transient Dynamic Mechanical Analysis of Resilin-based Elastomeric Hydrogels

NASA Astrophysics Data System (ADS)

Li, Linqing; Kiick, Kristi

2014-04-01

The outstanding high-frequency properties of emerging resilin-like polypeptides (RLPs) have motivated their development for vocal fold tissue regeneration and other applications. Recombinant RLP hydrogels show efficient gelation, tunable mechanical properties, and display excellent extensibility, but little has been reported about their transient mechanical properties. In this manuscript, we describe the transient mechanical behavior of new RLP hydrogels investigated via both sinusoidal oscillatory shear deformation and uniaxial tensile testing. Oscillatory stress relaxation and creep experiments confirm that RLP-based hydrogels display significantly reduced stress relaxation and improved strain recovery compared to PEG-based control hydrogels. Uniaxial tensile testing confirms the negligible hysteresis, reversible elasticity and superior resilience (up to 98%) of hydrated RLP hydrogels, with Young’s modulus values that compare favorably with those previously reported for resilin and that mimic the tensile properties of the vocal fold ligament at low strain (< 15%). These studies expand our understanding of the properties of these RLP materials under a variety of conditions, and confirm the unique applicability, for mechanically demanding tissue engineering applications, of a range of RLP hydrogels.

Programmable Hydrogels for Cell Encapsulation and Neo-Tissue Growth to Enable Personalized Tissue Engineering.

PubMed

Bryant, Stephanie J; Vernerey, Franck J

2018-01-01

Biomimetic and biodegradable synthetic hydrogels are emerging as a promising platform for cell encapsulation and tissue engineering. Notably, synthetic-based hydrogels offer highly programmable macroscopic properties (e.g., mechanical, swelling and transport properties) and degradation profiles through control over several tunable parameters (e.g., the initial network structure, degradation kinetics and behavior, and polymer properties). One component to success is the ability to maintain structural integrity as the hydrogel transitions to neo-tissue. This seamless transition is complicated by the fact that cellular activity is highly variable among donors. Thus, computational models provide an important tool in tissue engineering due to their unique ability to explore the coupled processes of hydrogel degradation and neo-tissue growth across multiple length scales. In addition, such models provide new opportunities to develop predictive computational tools to overcome the challenges with designing hydrogels for different donors. In this report, programmable properties of synthetic-based hydrogels and their relation to the hydrogel's structural properties and their evolution with degradation are reviewed. This is followed by recent progress on the development of computational models that describe hydrogel degradation with neo-tissue growth when cells are encapsulated in a hydrogel. Finally, the potential for predictive models to enable patient-specific hydrogel designs for personalized tissue engineering is discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Visible light induced electropolymerization of suspended hydrogel bioscaffolds in a microfluidic chip.

PubMed

Li, Pan; Yu, Haibo; Liu, Na; Wang, Feifei; Lee, Gwo-Bin; Wang, Yuechao; Liu, Lianqing; Li, Wen Jung

2018-05-23

The development of microengineered hydrogels co-cultured with cells in vitro could advance in vivo bio-systems in both structural complexity and functional hierarchy, which holds great promise for applications in regenerative tissues or organs, drug discovery and screening, and bio-sensors or bio-actuators. Traditional hydrogel microfabrication technologies such as ultraviolet (UV) laser or multiphoton laser stereolithography and three-dimensional (3D) printing systems have advanced the development of 3D hydrogel micro-structures but need either expensive and complex equipment, or harsh material selection with limited photoinitiators. Herein, we propose a simple and flexible hydrogel microfabrication method based on a ubiquitous visible-light projection system combined with a custom-designed photosensitive microfluidic chip, to rapidly (typically several to tens of seconds) fabricate various two-dimensional (2D) hydrogel patterns and 3D hydrogel constructs. A theoretical layer-by-layer model that involves continuous polymerizing-delaminating-polymerizing cycles is presented to explain the polymerization and structural formation mechanism of hydrogels. A large area of hydrogel patterns was efficiently fabricated without the usage of costly laser systems or photoinitiators, i.e., a stereoscopic mesh-like hydrogel network with intersecting hydrogel micro-belts was fabricated via a series of dynamic-changing digital light projections. The pores and gaps of the hydrogel network are tunable, which facilitates the supply of nutrients and discharge of waste in the construction of 3D thick bio-models. Cell co-culture experiments showed the effective regulation of cell spreading by hydrogel scaffolds fabricated by the new method presented here. This visible light enabled hydrogel microfabrication method may provide new prospects for designing cell-based units for advanced biomedical studies, e.g., for 3D bio-models or bio-actuators in the future.

Bacterial cellulose based hydrogel (BC-g-AA) and preliminary result of swelling behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hakam, Adil; Lazim, Azwan Mat; Abdul Rahman, I. Irman

2013-11-27

In this study, hydrogel based on Bacterial cellulose (BC) or local known as Nata de Coco, which grafted with monomer: Acrylic acid (AA) is synthesis by using gamma radiation technique. These hydrogel (BC-g-AA) has unique characteristic whereby responsive to pH buffer solution.

Synthesis and evaluation on pH- and temperature-responsive chitosan-p(MAA-co-NIPAM) hydrogels.

PubMed

Rasib, S Z M; Ahmad, Z; Khan, A; Akil, H M; Othman, M B H; Hamid, Z A A; Ullah, F

2018-03-01

In this study, chitosan-poly(methacrylic acid-co-N-isopropylacrylamide) [chitosan-p(MAA-co-NIPAM)] hydrogels were synthesized by emulsion polymerization. In order to be used as a carrier for drug delivery systems, the hydrogels had to be biocompatible, biodegradable and multi-responsive. The polymerization was performed by copolymerize MAA and NIPAM with chitosan polymer to produce a chitosan-based hydrogel. Due to instability during synthesis and complexity of components to produce the hydrogel, further study at different times of reaction is important to observe the synthesis process, the effect of end product on swelling behaviour and the most important is to find the best way to control the hydrogel synthesis in order to have an optimal swelling behaviour for drug release application. Studied by using Fourier transform infra-red (FTIR) spectroscopy found that, the synthesized was successfully produced stable chitosan-based hydrogel with PNIPAM continuously covered the outer surface of hydrogel which influenced much on the stability during synthesis. The chitosan and PMAA increased the zeta potential of the hydrogel and the chitosan capable to control shrinkage above human body temperature. The chitosan-p(MAA-co-NIPAM) hydrogels also responses to pH and temperature thus improved the ability to performance as a drug carrier. Copyright © 2017 Elsevier B.V. All rights reserved.

Injectable In Situ Forming Biodegradable Chitosan-Hyaluronic acid Based Hydrogels for Cartilage Tissue Engineering

PubMed Central

Tan, Huaping; Chu, Constance R.; Payne, Karin; Marra, Kacey G.

2009-01-01

Injectable, biodegradable scaffolds are important biomaterials for tissue engineering and drug delivery. Hydrogels derived from natural polysaccharides are ideal scaffolds as they resemble the extracellular matrices of tissues comprised of various glycosaminoglycans (GAG). Here, we report a new class of biocompatible and biodegradable composite hydrogels derived from water-soluble chitosan and oxidized hyaluronic acid upon mixing, without the addition of a chemical crosslinking agent. The gelation is attributed to the Schiff-base reaction between amino and aldehyde groups of polysaccharide derivatives. In the current work, N-succinyl-chitosan (S-CS) and aldehyde hyaluronic acid (A-HA) were synthesized for preparation of the composite hydrogels. The polysaccharide derivatives and composite hydrogels were characterized by FTIR spectroscopy. The effect of the ratio of S-CS and A-HA on the gelation time, microstructure, surface morphology, equilibrium swelling, compressive modulus, and in vitro degradation of composite hydrogels was examined. The potential of the composite hydrogel as an injectable scaffold was demonstrated by encapsulation of bovine articular chondrocytes within the composite hydrogel matrix in vitro. The results demonstrated that the composite hydrogel supported cell survival and the cells retained chondrocytic morphology. These characteristics provide a potential opportunity to use the injectable, composite hydrogels in tissue engineering applications. PMID:19167750

Influence of Different ECM-Like Hydrogels on Neurite Outgrowth Induced by Adipose Tissue-Derived Stem Cells

PubMed Central

Oliveira, E.; Assunção-Silva, R. C.; Teixeira, F. G.

2017-01-01

Mesenchymal stem cells (MSCs) have been proposed for spinal cord injury (SCI) applications due to their capacity to secrete growth factors and vesicles—secretome—that impacts important phenomena in SCI regeneration. To improve MSC survival into SCI sites, hydrogels have been used as transplantation vehicles. Herein, we hypothesized if different hydrogels could interact differently with adipose tissue-derived MSCs (ASCs). The efficacy of three natural hydrogels, gellan gum (functionalized with a fibronectin peptide), collagen, and a hydrogel rich in laminin epitopes (NVR-gel) in promoting neuritogenesis (alone and cocultured with ASCs), was evaluated in the present study. Their impact on ASC survival, metabolic activity, and gene expression was also evaluated. Our results indicated that all hydrogels supported ASC survival and viability, being this more evident for the functionalized GG hydrogels. Moreover, the presence of different ECM-derived biological cues within the hydrogels appears to differently affect the mRNA levels of growth factors involved in neuronal survival, differentiation, and axonal outgrowth. All the hydrogel-based systems supported axonal growth mediated by ASCs, but this effect was more robust in functionalized GG. The data herein presented highlights the importance of biological cues within hydrogel-based biomaterials as possible modulators of ASC secretome and its effects for SCI applications. PMID:29333166

A glucose-sensitive block glycopolymer hydrogel based on dynamic boronic ester bonds for insulin delivery.

PubMed

Cai, Baoqi; Luo, Yanping; Guo, Qianqian; Zhang, Xinge; Wu, Zhongming

2017-06-05

Hydrogels are good candidates to satisfy many needs for functional and tunable biomaterials. How to precisely control the gel structure and functions is crucial for the construction of sophisticated soft biomaterials comprising the hydrogels, which facilitates the impact of the surrounding environment on a unique biological function occurring. Here, glucose-responsive hydrogels comprised of 3-acrylamidophenyl boronic acid copolymerized with 2-lactobionamidoethyl methacrylate (p(APBA-b-LAMA)) were synthesized, and further evaluated as carriers for insulin delivery. The formation of (p(APBA-b-LAMA)) hydrogel was based on dynamic covalent bond using the association of boronic acid with diols. P(APBA-b-LAMA) hydrogel with the typical porous structure showed a rapid increase in equilibrium of swelling, which was up to 1856% after incubation with aqueous solution. Using insulin as a model protein therapeutic, p(APBA-b-LAMA) hydrogel exhibited high drug loading capability up to 15.6%, and also displayed glucose-dependent insulin release under physiological conditions. Additionally, the viability of NIH3T3 cells was more than 90% after treated with p(APBA-b-LAMA) hydrogel, indicating that the hydrogel had no cytotoxicity. Consequently, the novel p(APBA-b-LAMA) hydrogel has a practical application for diabetes treatment. Copyright © 2017. Published by Elsevier Ltd.

Biodegradable HEMA-based hydrogels with enhanced mechanical properties.

PubMed

Moghadam, Mohamadreza Nassajian; Pioletti, Dominique P

2016-08-01

Hydrogels are widely used in the biomedical field. Their main purposes are either to deliver biological active agents or to temporarily fill a defect until they degrade and are followed by new host tissue formation. However, for this latter application, biodegradable hydrogels are usually not capable to sustain any significant load. The development of biodegradable hydrogels presenting load-bearing capabilities would open new possibilities to utilize this class of material in the biomedical field. In this work, an original formulation of biodegradable photo-crosslinked hydrogels based on hydroxyethyl methacrylate (HEMA) is presented. The hydrogels consist of short-length poly(2-hydroxyethyl methacrylate) (PHEMA) chains in a star shape structure, obtained by introducing a tetra-functional chain transfer agent in the backbone of the hydrogels. They are cross-linked with a biodegradable N,O-dimethacryloyl hydroxylamine (DMHA) molecule sensitive to hydrolytic cleavage. We characterized the degradation properties of these hydrogels submitted to mechanical loadings. We showed that the developed hydrogels undergo long-term degradation and specially meet the two essential requirements of a biodegradable hydrogel suitable for load bearing applications: enhanced mechanical properties and low molecular weight degradation products. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1161-1169, 2016. © 2015 Wiley Periodicals, Inc.

Novel Fabrication of Biodegradable Superabsorbent Microspheres with Diffusion Barrier through Thermo-Chemical Modification and Their Potential Agriculture Applications for Water Holding and Sustained Release of Fertilizer.

PubMed

Feng, Diejing; Bai, Bo; Wang, Honglun; Suo, Yourui

2017-07-26

Synergistic utilization of water and fertilizer has vital contribution to the modern production of agriculture. This work reports on a simple and facile strategy to prepare biodegradable yeast/sodium alginate/poly(vinyl alcohol) superabsorbent microspheres with a diffusion barrier merit by thermo-chemical modification route. The integrated performances, including water absorbency, water retention, water evaporation ratio, leaching loss control, sustained-release behaviors, and degradation in soil, were systematically investigated. The results revealed that the modified microspheres were a triumphant water and fertilizer manager to effectively hold water and control the unexpected leakage of fertilizer for sustained release. Therefore, this work provides a promising approach to ameliorate the utilization efficiency of water and fertilizer in potential agriculture applications.

Bioinspired Smart Actuator Based on Graphene Oxide-Polymer Hybrid Hydrogels.

PubMed

Wang, Tao; Huang, Jiahe; Yang, Yiqing; Zhang, Enzhong; Sun, Weixiang; Tong, Zhen

2015-10-28

Rapid response and strong mechanical properties are desired for smart materials used in soft actuators. A bioinspired hybrid hydrogel actuator was designed and prepared by series combination of three trunks of tough polymer-clay hydrogels to accomplish the comprehensive actuation of "extension-grasp-retraction" like a fishing rod. The hydrogels with thermo-creep and thermo-shrinking features were successively irradiated by near-infrared (NIR) to execute extension and retraction, respectively. The GO in the hydrogels absorbed the NIR energy and transformed it into thermo-energy rapidly and effectively. The hydrogel with adhesion or magnetic force was adopted as the "hook" of the hybrid hydrogel actuator for grasping object. The hook of the hybrid hydrogel actuator was replaceable according to applications, even with functional materials other than hydrogels. This study provides an innovative concept to explore new soft actuators through combining response hydrogels and programming the same stimulus.

Poly(ethylene glycol) hydrogel microstructures encapsulating living cells

NASA Technical Reports Server (NTRS)

Koh, Won-Gun; Revzin, Alexander; Pishko, Michael V.

2002-01-01

We present an easy and effective method for the encapsulation of cells inside PEG-based hydrogel microstructures fabricated using photolithography. High-density arrays of three-dimensional microstructures were created on substrates using this method. Mammalian cells were encapsulated in cylindrical hydrogel microstructures of 600 and 50 micrometers in diameter or in cubic hydrogel structures in microfluidic channels. Reducing lateral dimension of the individual hydrogel microstructure to 50 micrometers allowed us to isolate 1-3 cells per microstructure. Viability assays demonstrated that cells remained viable inside these hydrogels after encapsulation for up to 7 days.

Preparation and characterisation of a novel hydrogel based on Auricularia polytricha β-glucan and its bio-release property for vitamin B12 delivery.

PubMed

Zhu, Kai; Chen, Xiaoyuan; Yu, Da; He, Yue; Song, Guanglei

2018-05-01

This study investigates a novel hydrogel synthesis method and its bio-release property. This hydrogel, with a three-dimensional network structure based on Auricularia polytricha β-glucan, was characterised by means of Fourier transform infrared spectroscopy, 1 H NMR and scanning electron microscopy. Vitamin B 12 (VB 12 , cobalamin) as a hydrophilic functional food component was entrapped into these hydrogels. The in vitro release profile of VB 12 was established in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The results showed that the hydrogel had medium pore size from 30 to 300 µm, and the swelling ratio increased with the degree of substitution. The hydrogel demonstrated good stability in SGF and bio-release capability in SIF for VB 12 . The accumulated release rate is about 80% in SIF and below 20% in SGF, which indicated the significant different release property in stomach and intestine. The Auricularia polytricha β-glucan-based hydrogel has a good swelling ratio, pepsin stability and pancrelipase-catalysed biodegradation property. The bio-release rate is significantly different in SIF and SGF, which indicated that this hydrogel could be a good intestinal target carrier of VB 12 . © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Microfluidic hydrogels for tissue engineering.

PubMed

Huang, Guo You; Zhou, Li Hong; Zhang, Qian Cheng; Chen, Yong Mei; Sun, Wei; Xu, Feng; Lu, Tian Jian

2011-03-01

With advanced properties similar to the native extracellular matrix, hydrogels have found widespread applications in tissue engineering. Hydrogel-based cellular constructs have been successfully developed to engineer different tissues such as skin, cartilage and bladder. Whilst significant advances have been made, it is still challenging to fabricate large and complex functional tissues due mainly to the limited diffusion capability of hydrogels. The integration of microfluidic networks and hydrogels can greatly enhance mass transport in hydrogels and spatiotemporally control the chemical microenvironment of cells, mimicking the function of native microvessels. In this review, we present and discuss recent advances in the fabrication of microfluidic hydrogels from the viewpoint of tissue engineering. Further development of new hydrogels and microengineering technologies will have a great impact on tissue engineering.

Preparation and physico-chemical properties of hydrogels from carboxymethyl cassava starch crosslinked with citric acid

NASA Astrophysics Data System (ADS)

Boonkham, Sasikan; Sangseethong, Kunruedee; Chatakanon, Pathama; Niamnuy, Chalida; Nakasaki, Kiyohiko; Sriroth, Klanarong

2014-06-01

Recently, environmentally friendly hydrogels prepared from renewable bio-based resources have drawn significant attention from both industrial and academic sectors. In this study, chemically crosslinked hydrogels have been developed from cassava starch which is a bio-based polymer using a non-toxic citric acid as a crosslinking agent. Cassava starch was first modified by carboxymethylation to improve its water absorbency property. The carboxymethyl cassava starch (CMCS) obtained was then crosslinked with citric acid at different concentrations and reaction times. The gel fraction of hydrogels increased progressively with increasing citric acid concentration. Free swelling capacity of hydrogels in de-ionized water, saline solution and buffers at various pHs as well as absorption under load were investigated. The results revealed that swelling behavior and mechanical characteristic of hydrogels depended on the citric acid concentration used in reaction. Increasing citric acid concentration resulted in hydrogels with stronger network but lower swelling and absorption capacity. The cassava starch hydrogels developed were sensitive to ionic strength and pH of surrounding medium, showing much reduced swelling capacity in saline salt solution and acidic buffers.

UV-crosslinkable and thermo-responsive chitosan hybrid hydrogel for NIR-triggered localized on-demand drug delivery.

PubMed

Wang, Lei; Li, Baoqiang; Xu, Feng; Xu, Zheheng; Wei, Daqing; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu

2017-10-15

Innovative drug delivery technologies based on smart hydrogels for localized on-demand drug delivery had aroused great interest. To acquire smart UV-crosslinkable chitosan hydrogel for NIR-triggered localized on-demanded drug release, a novel UV-crosslinkable and thermo-responsive chitosan was first designed and synthesized by grafting with poly N-isopropylacrylamide, acetylation of methacryloyl groups and embedding with photothermal carbon. The UV-crosslinkable unit (methacryloyl groups) endowed chitosan with gelation via UV irradiation. The thermo-responsive unit (poly N-isopropylacrylamide) endowed chitosan hydrogel with temperature-triggered volume shrinkage and reversible swelling/de-swelling behavior. The chitosan hybrid hydrogel embedded with photothermal carbon exhibited distinct NIR-triggered volume shrinkage (∼42% shrinkage) in response to temperature elevation as induced by NIR laser irradiation. As a demonstration, doxorubicin release rate was accelerated and approximately 40 times higher than that from non-irradiated hydrogels. The UV-crosslinkable and thermal-responsive hybrid hydrogel served as in situ forming hydrogel-based drug depot is developed for NIR-triggered localized on-demand release. Copyright © 2017 Elsevier Ltd. All rights reserved.

An improved correlation to predict molecular weight between crosslinks based on equilibrium degree of swelling of hydrogel networks.

PubMed

Jimenez-Vergara, Andrea C; Lewis, John; Hahn, Mariah S; Munoz-Pinto, Dany J

2018-04-01

Accurate characterization of hydrogel diffusional properties is of substantial importance for a range of biotechnological applications. The diffusional capacity of hydrogels has commonly been estimated using the average molecular weight between crosslinks (M c ), which is calculated based on the equilibrium degree of swelling. However, the existing correlation linking M c and equilibrium swelling fails to accurately reflect the diffusional properties of highly crosslinked hydrogel networks. Also, as demonstrated herein, the current model fails to accurately predict the diffusional properties of hydrogels when polymer concentration and molecular weight are varied simultaneously. To address these limitations, we evaluated the diffusional properties of 48 distinct hydrogel formulations using two different photoinitiator systems, employing molecular size exclusion as an alternative methodology to calculate average hydrogel mesh size. The resulting data were then utilized to develop a revised correlation between M c and hydrogel equilibrium swelling that substantially reduces the limitations associated with the current correlation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1339-1348, 2018. © 2017 Wiley Periodicals, Inc.

Stimuli-Responsive DNA-Based Hydrogels: From Basic Principles to Applications.

PubMed

Kahn, Jason S; Hu, Yuwei; Willner, Itamar

2017-04-18

The base sequence of nucleic acids encodes structural and functional information into the DNA biopolymer. External stimuli such as metal ions, pH, light, or added nucleic acid fuel strands provide triggers to reversibly switch nucleic acid structures such as metal-ion-bridged duplexes, i-motifs, triplex nucleic acids, G-quadruplexes, or programmed double-stranded hybrids of oligonucleotides (DNA). The signal-triggered oligonucleotide structures have been broadly applied to develop switchable DNA nanostructures and DNA machines, and these stimuli-responsive assemblies provide functional scaffolds for the rapidly developing area of DNA nanotechnology. Stimuli-responsive hydrogels undergoing signal-triggered hydrogel-to-solution transitions or signal-controlled stiffness changes attract substantial interest as functional matrices for controlled drug delivery, materials exhibiting switchable mechanical properties, acting as valves or actuators, and "smart" materials for sensing and information processing. The integration of stimuli-responsive oligonucleotides with hydrogel-forming polymers provides versatile means to exploit the functional information encoded in the nucleic acid sequences to yield stimuli-responsive hydrogels exhibiting switchable physical, structural, and chemical properties. Stimuli-responsive DNA-based nucleic acid structures are integrated in acrylamide polymer chains and reversible, switchable hydrogel-to-solution transitions of the systems are demonstrated by applying external triggers, such as metal ions, pH-responsive strands, G-quadruplex, and appropriate counter triggers that bridge and dissociate the polymer chains. By combining stimuli-responsive nucleic acid bridges with thermosensitive poly(N-isopropylacrylamide) (pNIPAM) chains, systems undergoing reversible solution ↔ hydrogel ↔ solid transitions are demonstrated. Specifically, by bridging acrylamide polymer chains by two nucleic acid functionalities, where one type of bridging unit provides a stimuli-responsive element and the second unit acts as internal "bridging memory", shape-memory hydrogels undergoing reversible and switchable transitions between shaped hydrogels and shapeless quasi-liquid states are demonstrated. By using stimuli-responsive hydrogel cross-linking units that can assemble the bridging units by two different input signals, the orthogonally-triggered functions of the shape-memory were shown. Furthermore, a versatile approach to assemble stimuli-responsive DNA-based acrylamide hydrogel films on surfaces is presented. The method involves the activation of the hybridization chain-reaction (HCR) by a surface-confined promoter strand, in the presence of acrylamide chains modified with two DNA hairpin structures and appropriate stimuli-responsive tethers. The resulting hydrogel-modified surfaces revealed switchable stiffness properties and signal-triggered catalytic functions. By applying the method to assemble the hydrogel microparticles, substrate-loaded, stimuli-responsive microcapsules are prepared. The signal-triggered DNA-based hydrogel microcapsules are applied as drug carriers for controlled release. The different potential applications and future perspectives of stimuli responsive hydrogels are discussed. Specifically, the use of these smart materials and assemblies as carriers for controlled drug release and as shape-memory matrices for information storage and inscription and the use of surface-confined stimuli-responsive hydrogels, exhibiting switchable stiffness properties, for catalysis and controlled growth of cells are discussed.

Functionalized graphene hydrogel-based high-performance supercapacitors.

PubMed

Xu, Yuxi; Lin, Zhaoyang; Huang, Xiaoqing; Wang, Yang; Huang, Yu; Duan, Xiangfeng

2013-10-25

Functionalized graphene hydrogels are prepared by a one-step low-temperature reduction process and exhibit ultrahigh specific capacitances and excellent cycling stability in the aqueous electrolyte. Flexible solid-state supercapacitors based on functionalized graphene hydrogels are demonstrated with superior capacitive performances and extraordinary mechanical flexibility. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Triblock Copolymer Design Leads to Robust Hybrid Hydrogels for High-Performance Flexible Supercapacitors.

PubMed

Zhang, Guangzhao; Chen, Yunhua; Deng, Yonghong; Wang, Chaoyang

2017-10-18

We report here an intriguing hybrid conductive hydrogel as electrode for high-performance flexible supercapacitor. The key is using a rationally designed water-soluble ABA triblock copolymer (termed as IAOAI) containing a central poly(ethylene oxide) block (A) and terminal poly(acrylamide) (PAAm) block with aniline moieties randomly incorporated (B), which was synthesized by reversible additional fragment transfer polymerization. The subsequent copolymerization of aniline monomers with the terminated aniline moieties on the IAOAI polymer generates a three-dimensional cross-linking hybrid network. The hybrid hydrogel electrode demonstrates robust mechanical flexibility, remarkable electrochemical capacitance (919 F/g), and cyclic stability (90% capacitance retention after 1000 cycles). Moreover, the flexible supercapacitor based on this hybrid hydrogel electrode presents a large specific capacitance (187 F/g), superior to most reported conductive hydrogel-based supercapacitors. With the demonstrated additional favorable cyclic stability and excellent capacitive and rate performance, this hybrid hydrogel-based supercapacitor holds great promise for flexible energy-storage device.

Multiphoton imaging of myogenic differentiation in gelatin-based hydrogels as tissue engineering scaffolds.

PubMed

Kim, Min Jeong; Shin, Yong Cheol; Lee, Jong Ho; Jun, Seung Won; Kim, Chang-Seok; Lee, Yunki; Park, Jong-Chul; Lee, Soo-Hong; Park, Ki Dong; Han, Dong-Wook

2016-01-01

Hydrogels can serve as three-dimensional (3D) scaffolds for cell culture and be readily injected into the body. Recent advances in the image technology for 3D scaffolds like hydrogels have attracted considerable attention to overcome the drawbacks of ordinary imaging technologies such as optical and fluorescence microscopy. Multiphoton microscopy (MPM) is an effective method based on the excitation of two-photons. In the present study, C2C12 myoblasts differentiated in 3D gelatin hydroxyphenylpropionic acid (GHPA) hydrogels were imaged by using a custom-built multiphoton excitation fluorescence microscopy to compare the difference in the imaging capacity between conventional microscopy and MPM. The physicochemical properties of GHPA hydrogels were characterized by using scanning electron microscopy and Fourier-transform infrared spectroscopy. In addition, the cell viability and proliferation of C2C12 myoblasts cultured in the GHPA hydrogels were analyzed by using Live/Dead Cell and CCK-8 assays, respectively. It was found that C2C12 cells were well grown and normally proliferated in the hydrogels. Furthermore, the hydrogels were shown to be suitable to facilitate the myogenic differentiation of C2C12 cells incubated in differentiation media, which had been corroborated by MPM. It was very hard to get clear images from a fluorescence microscope. Our findings suggest that the gelatin-based hydrogels can be beneficially utilized as 3D scaffolds for skeletal muscle engineering and that MPM can be effectively applied to imaging technology for tissue regeneration.

A postoperative anti-adhesion barrier based on photoinduced imine-crosslinking hydrogel with tissue-adhesive ability.

PubMed

Yang, Yunlong; Liu, Xiaolin; Li, Yan; Wang, Yang; Bao, Chunyan; Chen, Yunfeng; Lin, Qiuning; Zhu, Linyong

2017-10-15

Postoperative adhesion is a serious complication that can further lead to morbidity and/or mortality. Polymer anti-adhesion barrier material provides an effective precaution to reduce the probability of postoperative adhesion. Clinical application requires these materials to be easily handled, biocompatible, biodegradable, and most importantly tissue adherent to provide target sites with reliable isolation. However, currently there is nearly no polymer barrier material that can fully satisfy these requirements. In this study, based on the photoinduced imine-crosslinking (PIC) reaction, we had developed a photo-crosslinking hydrogel (CNG hydrogel) that composed of o-nitrobenzyl alcohol (NB) modified carboxymethyl cellulose (CMC-NB) and glycol chitosan (GC) as an anti-adhesion barrier material. Under light irradiation, CMC-NB generated aldehyde groups which subsequently reacted with amino groups distributed on GC or tissue surface to form a hydrogel barrier that covalently attached to tissue surface. Rheological analysis demonstrated that CNG hydrogel (30mg/mL polymer content) could be formed in 30s upon light irradiation. Tissue adhesive tests showed that the tissue adhesive strength of CNG hydrogel (30mg/mL) was about 8.32kPa-24.65kPa which increased with increasing CMC-NB content in CNG hydrogel. Toxicity evaluation by L929 cells demonstrated that CNG hydrogel was cytocompatible. Furthermore, sidewall defect-cecum abrasion model of rat was employed to evaluate the postoperative anti-adhesion efficacy of CNG hydrogel. And a significantly reduction of tissue adhesion (20% samples with low score adhesion) was found in CNG hydrogel treated group, compared with control group (100% samples with high score adhesion). In addition, CNG hydrogel could be degraded in nearly 14days and showed no side effect on wound healing. These findings indicated that CNG hydrogel can effectively expanded the clinical treatments of postoperative tissue adhesion. In this study, a tissue adhesive photo-crosslinking hydrogel (CNG) was developed based on photo-induced imine crosslinking reaction (PIC) for postoperative anti-adhesion. CNG hydrogel showed the features of easy and convenient operation, fast and controllable gelation, suitable gel strength, good biocompatibility, and most importantly strong tissue adhesiveness. Therefore, it shows very high performance to prevent postoperative tissue adhesion. Overall, our study provides a more suitable hydrogel barrier material that can overcome the shortcomings of current barriers for clinical postoperative anti-adhesion. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis and characterization of psyllium-NVP based drug delivery system through radiation crosslinking polymerization

NASA Astrophysics Data System (ADS)

Singh, Baljit; Kumar, S.

2008-08-01

In order to develop the hydrogels meant for the drug delivery, we have prepared psyllium- N-vinylpyrrolidone (NVP) based hydrogels by radiation induced crosslinking. Polymers were characterized with SEMs, FTIR and swelling studies. Swelling of the hydrogels was studied as a function of monomer concentration, total radiation dose, temperature, pH and [NaCl] of the swelling medium. The swelling kinetics of the hydrogels and release dynamics of anticancer model drug (5-fluorouracil) from the hydrogels have been carried out for the evaluation of swelling and drug release mechanism. It has been observed that diffusion exponent ' n' have 0.8, 0.9, 0.8 and gel characteristics constant ' k' have 9.22 × 10 -3, 2.06 × 10 -3, 11.72 × 10 -3 values for the release of drug from the drug loaded hydrogels in distilled water, pH 2.2 buffer and pH 7.4 buffer, respectively. The present study shows that the release of drug from the hydrogels occurred through Non-Fickian diffusion mechanism.

Novel vaginal drug delivery system: deformable propylene glycol liposomes-in-hydrogel.

PubMed

Vanić, Željka; Hurler, Julia; Ferderber, Kristina; Golja Gašparović, Petra; Škalko-Basnet, Nataša; Filipović-Grčić, Jelena

2014-03-01

Deformable propylene glycol-containing liposomes (DPGLs) incorporating metronidazole or clotrimazole were prepared and evaluated as an efficient drug delivery system to improve the treatment of vaginal microbial infections. The liposome formulations were optimized based on sufficient trapping efficiencies for both drugs and membrane elasticity as a prerequisite for successful permeability and therapy. An appropriate viscosity for vaginal administration was achieved by incorporating the liposomes into Carbopol hydrogel. DPGLs were able to penetrate through the hydrogel network more rapidly than conventional liposomes. In vitro studies of drug release from the liposomal hydrogel under conditions simulating human treatment confirmed sustained and diffusion-based drug release. Characterization of the rheological and textural properties of the DPGL-containing liposomal hydrogels demonstrated that the incorporation of DPGLs alone had no significant influence on mechanical properties of hydrogels compared to controls. These results support the great potential of DPGL-in-hydrogel as an efficient delivery system for the controlled and sustained release of antimicrobial drugs in the vagina.

Evaluation of fibrin-gelatin hydrogel as biopaper for application in skin bioprinting: An in-vitro study.

PubMed

Hakam, Mohammad Sadjad; Imani, Rana; Abolfathi, Nabiollah; Fakhrzadeh, Hossein; Sharifi, Ali Mohammad

2016-01-01

Recent advances in tissue engineering have led to the development of the concept of bioprinting as an interesting alternative to traditional tissue engineering approaches. Biopaper, a biomimetic hydrogel, is an essential component of the bioprinting process. The aim of this work was to synthesize a biopaper made of fibrin-gelatin hybrid hydrogel for application in skin bioprinting. Different composition percentages of the two biopolymer hydrogels, fibrin-gelatin, have been studied for the construction of the biopaper and were examined in terms of water absorption, biodegradability, glucose absorption, mechanical properties and water vapor transmission. Subsequently, tissue fusion study was performed on prepared 3T3 fibroblast cell line pellets embedded into the hydrogel. Based on the obtained results, fibrin-gelatin blend hydrogel with the same proportion of two components provides a natural scaffold for fibroblast-based bioink embedding and culture. The suggested optimized hydrogel was a suitable candidate as a biopaper for skin bioprinting technology.

Injectable and body temperature sensitive hydrogels based on chitosan and hyaluronic acid for pH sensitive drug release.

PubMed

Zhang, Wei; Jin, Xin; Li, Heng; Zhang, Run-Run; Wu, Cheng-Wei

2018-04-15

Hydrogels based on chitosan/hyaluronic acid/β-sodium glycerophosphate demonstrate injectability, body temperature sensitivity, pH sensitive drug release and adhesion to cancer cell. The drug (doxorubicin) loaded hydrogel precursor solutions are injectable and turn to hydrogels when the temperature is increased to body temperature. The acidic condition (pH 4.00) can trigger the release of drug and the cancer cell (Hela) can adhere to the surface of the hydrogels, which will be beneficial for tumor site-specific administration of drug. The mechanical strength, the gelation temperature, and the drug release behavior can be tuned by varying hyaluronic acid content. The mechanisms were characterized using dynamic mechanical analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and fluorescence microscopy. The carboxyl group in hyaluronic acid can form the hydrogen bondings with the protonated amine in chitosan, which promotes the increase of mechanical strength of the hydrogels and depresses the initial burst release of drug from the hydrogel. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biodegradable Cellulose-based Hydrogels: Design and Applications

PubMed Central

Sannino, Alessandro; Demitri, Christian; Madaghiele, Marta

2009-01-01

Hydrogels are macromolecular networks able to absorb and release water solutions in a reversible manner, in response to specific environmental stimuli. Such stimuli-sensitive behaviour makes hydrogels appealing for the design of ‘smart’ devices, applicable in a variety of technological fields. In particular, in cases where either ecological or biocompatibility issues are concerned, the biodegradability of the hydrogel network, together with the control of the degradation rate, may provide additional value to the developed device. This review surveys the design and the applications of cellulose-based hydrogels, which are extensively investigated due to the large availability of cellulose in nature, the intrinsic degradability of cellulose and the smart behaviour displayed by some cellulose derivatives.

Glutathione-Triggered Formation of a Fmoc-Protected Short Peptide-Based Supramolecular Hydrogel

PubMed Central

Shi, Yang; Wang, Jingyu; Wang, Huaimin; Hu, Yanhui; Chen, Xuemei; Yang, Zhimou

2014-01-01

A biocompatible method of glutathione (GSH) catalyzed disulfide bond reduction was used to form Fmoc-short peptide-based supramolecular hydrogels. The hydrogels could form in both buffer solution and cell culture medium containing 10% of Fetal Bovine Serum (FBS) within minutes. The hydrogel was characterized by rheology, transmission electron microscopy, and fluorescence emission spectra. Their potential in three dimensional (3D) cell culture was evaluated and the results indicated that the gel with a low concentration of the peptide (0.1 wt%) was suitable for 3D cell culture of 3T3 cells. This study provides an alternative candidate of supramolecular hydrogel for 3D cell culture and cell delivery. PMID:25222132

Synthesis and Characterization of Poly(Ethylene Glycol) Based Thermo-Responsive Hydrogels for Cell Sheet Engineering.

PubMed

Son, Kuk Hui; Lee, Jin Woo

2016-10-20

The swelling properties and thermal transition of hydrogels can be tailored by changing the hydrophilic-hydrophobic balance of polymer networks. Especially, poly( N -isopropylacrylamide) (PNIPAm) has received attention as thermo-responsive hydrogels for tissue engineering because its hydrophobicity and swelling property are transited around body temperature (32 °C). In this study, we investigated the potential of poly(ethylene glycol) diacrylate (PEGDA) as a hydrophilic co-monomer and crosslinker of PNIPAm to enhance biological properties of PNIPAm hydrogels. The swelling ratios, lower critical solution temperature (LCST), and internal pore structure of the synthesized p(NIPAm- co -PEGDA) hydrogels could be varied with changes in the molecular weight of PEGDA and the co-monomer ratios (NIPAm to PEGDA). We found that increasing the molecular weight of PEGDA showed an increase of pore sizes and swelling ratios of the hydrogels. In contrast, increasing the weight ratio of PEGDA under the same molecular weight condition increased the crosslinking density and decreased the swelling ratios of the hydrogels. Further, to evaluate the potential of these hydrogels as cell sheets, we seeded bovine chondrocytes on the p(NIPAm- co -PEGDA) hydrogels and observed the proliferation of the seed cells and their detachment as a cell sheet upon a decrease in temperature. Based on our results, we confirmed that p(NIPAm- co -PEGDA) hydrogels could be utilized as cell sheets with enhanced cell proliferation performance.

Soft contact lens biomaterials from bioinspired phospholipid polymers.

PubMed

Goda, Tatsuro; Ishihara, Kazuhiko

2006-03-01

Soft contact lens (SCL) biomaterials originated from the discovery of a poly(2-hydroxyethyl methacrylate) (poly[HEMA])-based hydrogel in 1960. Incorporation of hydrophilic polymers into poly(HEMA) hydrogels was performed in the 1970-1980s, which brought an increase in the equilibrium water content, leading to an enhancement of the oxygen permeability. Nowadays, the poly(HEMA)-based hydrogels have been applied in disposable SCL. At the same time, high oxygen-permeable silicone hydrogels were produced, which made it possible to continually wear SCL. Recently, numerous trials for improving the water wettability of silicone hydrogels have been performed. However, little attention has been paid to improving their anti-biofouling properties and biocompatibility. Since biomimetic phospholipid polymers possess excellent anti-biofouling properties and biocompatibility they have the potential to play a valuable role in the surface modification of the silicone hydrogel. The representative phospholipid polymers containing a 2-methacryloyloxyethyl phosphorylcholine (MPC) unit suppressed nonspecific protein adsorption, increased cell compatibility and contributed to blood compatible biomaterials. The MPC polymer coating on the silicone hydrogel improved its water wettability and biocompatibility, while maintaining high oxygen permeability compared with the original silicone hydrogel. Furthermore, the newly prepared phospholipid-type intermolecular crosslinker made it possible to synthesize a 100% phospholipid polymer hydrogel that can enhance the anti-biofouling properties and biocompatibility. In this review, the authors discuss how polymer hydrogels should be designed in order to obtain a biocompatible SCL and future perspectives.

pH-sensitive Itaconic acid based polymeric hydrogels for dye removal applications.

PubMed

Sakthivel, M; Franklin, D S; Guhanathan, S

2016-12-01

A series of Itaconic Acid (IA) based pH-sensitive polymeric hydrogels were synthesized by condensation polymerization of Itaconic Acid (IA) with Ethylene Glycol (EG) in the presence of an acid medium resulted into pre-polymer. Further, pre-polymer were co-polymerized with Acrylic Acid (AA) through free radical polymerization using Potassium persulphate (KPS). The structural and surface morphological characterizations of the synthesized hydrogels were studied using FT-IR spectroscopy and Scanning Electron Microscope (SEM) respectively. The swelling and swelling equilibrium were performed at varies pH (4.0-10.0). Further, the effects of IA, EG and AA on swelling properties have also been investigated. Thermal stability of synthesized hydrogels have been investigated by TGA, DTA and DSC. The synthesized hydrogels have shown good ability to uptake a Cationic dye. The Methylene blue has been chosen as a model cationic dye. The results of dye removal using IA hydrogels found to have excellent dye removal capacity. Such kind of IA based hydrogels may be recommended for eco-friendly environmental application. viz., removal of dyes and metal ions and sewage water treatment, purification of water etc. Copyright © 2015 Elsevier Inc. All rights reserved.

A facile prestrain-stick-release assembly of stretchable supercapacitors based on highly stretchable and sticky hydrogel electrolyte

NASA Astrophysics Data System (ADS)

Tang, Qianqiu; Chen, Mingming; Wang, Gengchao; Bao, Hua; Saha, Petr

2015-06-01

A facile prestrain-stick-release assembly strategy for the stretchable supercapacitor device is developed based on a novel Na2SO4-aPUA/PAAM hydrogel electrolyte, saving the stretchable rubber base conventionally used. The Na2SO4-aPUA/PAAM hydrogel electrolyte exhibits high stretchability (>1000%), electrical conductivity (0.036 S cm-1) and stickiness. Due to the unique features of the hydrogel electrolyte, the carbon nanotube@MnO2 film electrodes can be firmly stuck to two sides of the prestrained hydrogel electrolyte. Then, by releasing the hydrogel electrolyte, homogenous buckles are formed for the film electrodes to get a full stretchable supercapacitor device. Besides, the high stickiness of the hydrogel electrolyte ensures its strong adhesion with the film electrodes, facilitating ion and electronic transfer of the supercapacitor. As a result, excellent electrochemical performance is achieved with the specific capacitance of 478.6 mF cm-2 at 0.5 mA cm-2 (corresponding to 201.1 F g-1) and capacitance retention of 91.5% after 3000 charging-discharging cycles under 150% strain, which is the best for the stretchable supercapacitors.

3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering.

PubMed

Cochis, Andrea; Bonetti, Lorenzo; Sorrentino, Rita; Contessi Negrini, Nicola; Grassi, Federico; Leigheb, Massimiliano; Rimondini, Lia; Farè, Silvia

2018-04-10

A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na₂SO₄ and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues.

Elastin Based Cell-laden Injectable Hydrogels with Tunable Gelation, Mechanical and Biodegradation Properties

PubMed Central

Fathi, Ali; Mithieux, Suzanne M.; Wei, Hua; Chrzanowski, Wojciech; Valtchev, Peter; Weiss, Anthony S.; Dehghani, Fariba

2015-01-01

Injectable hydrogels made from extracellular matrix proteins such as elastin show great promise for various biomedical applications. Use of cytotoxic reagents, fixed gelling behavior, and lack of mechanical strength in these hydrogels are the main associated drawbacks. The aim of this study was to develop highly cytocompatible and injectable elastin-based hydrogels with alterable gelation characteristics, favorable mechanical properties and structural stability for load bearing applications. A thermoresponsive copolymer, poly(N-isopropylacrylamide-co-polylactide-2-hydroxyethyl methacrylate-co-oligo(ethylene glycol)monomethyl ether methacrylate, was functionalized with succinimide ester groups by incorporating N-acryloxysuccinimide monomer. These ester groups were exploited to covalently bond this polymer, denoted as PNPHO, to different proteins with primary amine groups such as α-elastin in aqueous media. The incorporation of elastin through covalent bond formation with PNPHO promotes the structural stability, mechanical properties and live cell proliferation within the structure of hydrogels. Our results demonstrated that elastin-co-PNPHO solutions were injectable through fine gauge needles and converted to hydrogels in situ at 37 °C in the absence of any crosslinking reagent. By altering PNPHO content, the gelling time of these hydrogels can be finely tuned within the range of 2 to 15 min to ensure compatibility with surgical requirements. In addition, these hydrogels exhibited compression moduli in the range of 40 to 145 kPa, which are substantially higher than those of previously developed elastin-based hydrogels. These hydrogels were highly stable in the physiological environment with the evidence of 10 wt% mass loss in 30 days of incubation in a simulated environment. This class of hydrogels is in vivo bioabsorbable due to the gradual increase of the lower critical solution temperature of the copolymer to above 37 °C due to the cleavage of polylactide from the PNPHO copolymer. Moreover, our results demonstrated that more than 80% of cells encapsulated in these hydrogels remained viable, and the number of encapsulated cells increased for at least 5 days. These unique properties mark elastin-co-PNHPO hydrogels as favorable candidates for a broad range of tissue engineering applications. PMID:24731705

Biocompatible and biodegradable dual-drug release system based on silk hydrogel containing silk nanoparticles.

PubMed

Numata, Keiji; Yamazaki, Shoya; Naga, Naofumi

2012-05-14

We developed a facile and quick ethanol-based method for preparing silk nanoparticles and then fabricated a biodegradable and biocompatible dual-drug release system based on silk nanoparticles and the molecular networks of silk hydrogels. Model drugs incorporated in the silk nanoparticles and silk hydrogels showed fast and constant release, respectively, indicating successful dual-drug release from silk hydrogel containing silk nanoparticles. The release behaviors achieved by this dual-drug release system suggest to be regulated by physical properties (e.g., β-sheet contents and size of the silk nanoparticles and network size of the silk hydrogels), which is an important advantage for biomedical applications. The present silk-based system for dual-drug release also demonstrated no significant cytotoxicity against human mesenchymal stem cells (hMSCs), and thus, this silk-based dual-drug release system has potential as a versatile and useful new platform of polymeric materials for various types of dual delivery of bioactive molecules.

Self-healing polysaccharide-based hydrogels as injectable carriers for neural stem cells

PubMed Central

Wei, Zhao; Zhao, Jingyi; Chen, Yong Mei; Zhang, Pengbo; Zhang, Qiqing

2016-01-01

Self-healing injectable hydrogels can be formulated as three-dimensional carriers for the treatment of neurological diseases with desirable advantages, such as avoiding the potential risks of cell loss during injection, protecting cells from the shearing force of injection. However, the demands for biocompatible self-healing injectable hydrogels to meet above requirements and to promote the differentiation of neural stem cells (NSCs) into neurons remain a challenge. Herein, we developed a biocompatible self-healing polysaccharide-based hydrogel system as a novel injectable carrier for the delivery of NSCs. N-carboxyethyl chitosan (CEC) and oxidized sodium alginate (OSA) are the main backbones of the hydrogel networks, denoted as CEC-l-OSA hydrogel (“l” means “linked-by”). Owing to the dynamic imine cross-links formed by a Schiff reaction between amino groups on CEC and aldehyde groups on OSA, the hydrogel possesses the ability to self-heal into a integrity after being injected from needles under physiological conditions. The CEC-l-OSA hydrogel in which the stiffness mimicking nature brain tissues (100~1000 Pa) can be finely tuned to support the proliferation and neuronal differentiation of NSCs. The multi-functional, injectable, and self-healing CEC-l-OSA hydrogels hold great promises for NSC transplantation and further treatment of neurological diseases. PMID:27897217

Chitosan-based thermosensitive hydrogel as a promising ocular drug delivery system: preparation, characterization, and in vivo evaluation.

PubMed

Chen, Xingwei; Li, Xinru; Zhou, Yanxia; Wang, Xiaoning; Zhang, Yanhui; Fan, Yating; Huang, Yanqing; Liu, Yan

2012-11-01

The purpose of this study was to evaluate the feasibility of in situ thermosensitive hydrogel based on chitosan in combination with disodium α-d-Glucose 1-phosphate (DGP) for ocular drug delivery system. Aqueous solution of chitosan/DGP underwent sol-gel transition as temperature increased which was flowing sol at room temperature and then turned into non-flowing hydrogel at physiological temperature. The properties of gels were characterized regarding gelation time, gelation temperature, and morphology. The sol-to-gel phase transition behaviors were affected by the concentrations of chitosan, DGP and the model drug levocetirizine dihydrochloride (LD). The developed hydrogel presented a characteristic of a rapid release at the initial period followed by a sustained release and remarkably enhanced the cornea penetration of LD. The results of ocular irritation demonstrated the excellent ocular tolerance of the hydrogel. The ocular residence time for the hydrogel was significantly prolonged compared with eye drops. The drug-loaded hydrogel produced more effective anti-allergic conjunctivitis effects compared with LD aqueous solution. These results showed that the chitosan/DGP thermosensitive hydrogel could be used as an ideal ocular drug delivery system in terms of the suitable sol-gel transition temperature, mild pH environment in the hydrogel as well as the organic solvent free.

Self-healing polysaccharide-based hydrogels as injectable carriers for neural stem cells

NASA Astrophysics Data System (ADS)

Wei, Zhao; Zhao, Jingyi; Chen, Yong Mei; Zhang, Pengbo; Zhang, Qiqing

2016-11-01

Self-healing injectable hydrogels can be formulated as three-dimensional carriers for the treatment of neurological diseases with desirable advantages, such as avoiding the potential risks of cell loss during injection, protecting cells from the shearing force of injection. However, the demands for biocompatible self-healing injectable hydrogels to meet above requirements and to promote the differentiation of neural stem cells (NSCs) into neurons remain a challenge. Herein, we developed a biocompatible self-healing polysaccharide-based hydrogel system as a novel injectable carrier for the delivery of NSCs. N-carboxyethyl chitosan (CEC) and oxidized sodium alginate (OSA) are the main backbones of the hydrogel networks, denoted as CEC-l-OSA hydrogel (“l” means “linked-by”). Owing to the dynamic imine cross-links formed by a Schiff reaction between amino groups on CEC and aldehyde groups on OSA, the hydrogel possesses the ability to self-heal into a integrity after being injected from needles under physiological conditions. The CEC-l-OSA hydrogel in which the stiffness mimicking nature brain tissues (100~1000 Pa) can be finely tuned to support the proliferation and neuronal differentiation of NSCs. The multi-functional, injectable, and self-healing CEC-l-OSA hydrogels hold great promises for NSC transplantation and further treatment of neurological diseases.

Gene Therapy Vectors with Enhanced Transfection Based on Hydrogels Modified with Affinity Peptides

PubMed Central

Shepard, Jaclyn A.; Wesson, Paul J.; Wang, Christine E.; Stevans, Alyson C.; Holland, Samantha J.; Shikanov, Ariella; Grzybowski, Bartosz A.; Shea, Lonnie D.

2011-01-01

Regenerative strategies for damaged tissue aim to present biochemical cues that recruit and direct progenitor cell migration and differentiation. Hydrogels capable of localized gene delivery are being developed to provide a support for tissue growth, and as a versatile method to induce the expression of inductive proteins; however, the duration, level, and localization of expression isoften insufficient for regeneration. We thus investigated the modification of hydrogels with affinity peptides to enhance vector retention and increase transfection within the matrix. PEG hydrogels were modified with lysine-based repeats (K4, K8), which retained approximately 25% more vector than control peptides. Transfection increased 5- to 15-fold with K8 and K4 respectively, over the RDG control peptide. K8- and K4-modified hydrogels bound similar quantities of vector, yet the vector dissociation rate was reduced for K8, suggesting excessive binding that limited transfection. These hydrogels were subsequently applied to an in vitro co-culture model to induce NGF expression and promote neurite outgrowth. K4-modified hydrogels promoted maximal neurite outgrowth, likely due to retention of both the vector and the NGF. Thus, hydrogels modified with affinity peptides enhanced vector retention and increased gene delivery, and these hydrogels may provide a versatile scaffold for numerous regenerative medicine applications. PMID:21514659

Facile synthesis of degradable and electrically conductive polysaccharide hydrogels.

PubMed

Guo, Baolin; Finne-Wistrand, Anna; Albertsson, Ann-Christine

2011-07-11

Degradable and electrically conductive polysaccharide hydrogels (DECPHs) have been synthesized by functionalizing polysaccharide with conductive aniline oligomers. DECPHs based on chitosan (CS), aniline tetramer (AT), and glutaraldehyde were obtained by a facile one-pot reaction by using the amine group of CS and AT under mild conditions, which avoids the multistep reactions and tedious purification involved in the synthesis of degradable conductive hydrogels in our previous work. Interestingly, these one-pot hydrogels possess good film-forming properties, electrical conductivity, and a pH-sensitive swelling behavior. The chemical structure and morphology before and after swelling of the hydrogels were verified by FT-IR, NMR, and SEM. The conductivity of the hydrogels was tuned by adjusting the content of AT. The swelling ratio of the hydrogels was altered by the content of tetraaniline and cross-linker. The hydrogels underwent slow degradation in a buffer solution. The hydrogels obtained by this facile approach provide new possibilities in biomedical applications, for example, biodegradable conductive hydrogels, films, and scaffolds for cardiovascular tissue engineering and controlled drug delivery.

Green synthesis of tea Ag nanocomposite hydrogels via mint leaf extraction for effective antibacterial activity.

PubMed

Jayaramudu, Tippabattini; Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Sadiku, E R; Mohana Raju, Konduru; Amalraj, John

2017-10-01

In this report, we investigated the swelling behavior and antibacterial property of nanosilver composite hydrogels made from tea with polyacrylamide via a free-radical polymerization and green process technique. This is probably for the first time; tea-based nano silver composite hydrogels were developed. The composite hydrogels comprise embedded nano silver particles in the tea hydrogel matrix via a green process with mint leaf extract. The size of the nano silver particles in the hydrogel matrix was found to be < 10 nm. The nano silver composite hydrogels formed and their blank hydrogels from the mint leaf were characterized by using ultraviolet-visible spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy, thermogravimetric analysis and X-ray diffraction studies. The nano silver composite hydrogels developed exhibit eminent antibacterial activity against Escherichia coli and Staphylococcus aureus. This clearly indicates that the nano silver composite hydrogels are potential candidates for antimicrobial applications.

Formulation and evaluation of microemulsion-based hydrogel for topical delivery

PubMed Central

Sabale, Vidya; Vora, Sejal

2012-01-01

Background: The purpose of this study was to develop microemulsion-based hydrogel formulation for topical delivery of bifonazole with an objective to increase the solubility and skin permeability of the drug. Materials and Methods: Oleic acid was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems. The pseudo-ternary phase diagrams for microemulsion regions were constructed using oleic acid as the oil, Tween 80 as the surfactant and isopropyl alcohol (IPA) as the cosurfactant. Various microemulsion formulations were prepared and optimized by 32 factorial design on the basis of percentage (%) transmittance, globule size, zeta potential, drug release, and skin permeability. The abilities of various microemulsions to deliver bifonazole through the skin were evaluated ex vivo using Franz diffusion cells fitted with rat skins. The Hydroxy Propyl Methyl Cellulose (HPMC) K100 M as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The optimized microemulsion-based hydrogel was evaluated for viscosity, spreadability, skin irritancy, skin permeability, stability, and antifungal activity by comparing it with marketed bifonazole cream. Results: The mechanism of drug release from microemulsion-based hydrogel was observed to follow zero order kinetics. The studied optimized microemulsion-based hydrogel showed a good stability over the period of 3 months. Average globule size of optimized microemulsion (F5) was found to be 18.98 nm, zeta potential was found to be -5.56 mv, and permeability of drug from microemulsion within 8 h was observed 84%. The antifungal activity of microemulsion-based hydrogel was found to be comparable with marketed cream. Conclusion: The results indicate that the studied microemulsion-based hydrogel (F5) has a potential for sustained action of drug release and it may act as promising vehicle for topical delivery of ibuprofen. PMID:23373005

Modulation of cultured neural networks using neurotrophin release from hydrogel-coated microelectrode arrays

NASA Astrophysics Data System (ADS)

Jun, Sang Beom; Hynd, Matthew R.; Dowell-Mesfin, Natalie M.; Al-Kofahi, Yousef; Roysam, Badrinath; Shain, William; Kim, Sung June

2008-06-01

Polyacrylamide and poly(ethylene glycol) diacrylate hydrogels were synthesized and characterized for use as drug release and substrates for neuron cell culture. Protein release kinetics was determined by incorporating bovine serum albumin (BSA) into hydrogels during polymerization. To determine if hydrogel incorporation and release affect bioactivity, alkaline phosphatase was incorporated into hydrogels and a released enzyme activity determined using the fluorescence-based ELF-97 assay. Hydrogels were then used to deliver a brain-derived neurotrophic factor (BDNF) from hydrogels polymerized over planar microelectrode arrays (MEAs). Primary hippocampal neurons were cultured on both control and neurotrophin-containing hydrogel-coated MEAs. The effect of released BDNF on neurite length and process arborization was investigated using automated image analysis. An increased spontaneous activity as a response to the released BDNF was recorded from the neurons cultured on the top of hydrogel layers. These results demonstrate that proteins of biological interest can be incorporated into hydrogels to modulate development and function of cultured neural networks. These results also set the stage for development of hydrogel-coated neural prosthetic devices for local delivery of various biologically active molecules.

Photothermal fabrication of microscale patterned DNA hydrogels

NASA Astrophysics Data System (ADS)

Shimomura, Suguru; Nishimura, Takahiro; Ogura, Yusuke; Tanida, Jun

2018-02-01

This paper introduces a method for fabricating microscale DNA hydrogels using irradiation with patterned light. Optical fabrication allows for the flexible and tunable formation of DNA hydrogels without changing the environmental conditions. Our scheme is based on local heat generation via the photothermal effect, which is induced by light irradiation on a quenching species. We demonstrate experimentally that, depending on the power and irradiation time, light irradiation enables the creation of local microscale DNA hydrogels, while the shapes of the DNA hydrogels are controlled by the irradiation patterns.

Effects of water-saving superabsorbent polymer on antioxidant enzyme activities and lipid peroxidation in corn (Zea mays L.) under drought stress.

PubMed

Islam, M Robiul; Hu, Yuegao; Mao, Sishuai; Jia, Pengfei; Eneji, A Egrinya; Xue, Xuzhang

2011-03-30

Drought is the most important abiotic stress factor limiting corn (Zea mays L.) growth and productivity. Therefore efficient management of soil moisture and study of metabolic changes in response to drought are important for improved production of corn. The objective of the present study was to gain a better understanding of drought tolerance mechanisms and improve soil water management strategies using a water-saving superabsorbent polymer (SAP) at 30 kg ha(-1) under three irrigation levels (adequate, moderate and deficit) using a new type of hydraulic pressure-controlled auto-irrigator. The results showed that relative water content and leaf water potential were much higher in corn treated with SAP. Although application of SAP reduced biomass accumulation by 11.1% under adequate irrigation, it increased the biomass markedly by 39.0% under moderate irrigation and 98.7% under deficit irrigation. Plants treated with SAP under deficit irrigation showed a significant decrease in superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase activities in leaves compared with control plants. The results of this study suggest that drought stress causes the production of oxygen radicals, leading to increased lipid peroxidation and oxidative stress in plants, and the application of a superabsorbent polymer could conserve soil water, making it available to plants for quenching oxidative stress and increasing biomass accumulation, especially under severe water stress. Copyright © 2010 Society of Chemical Industry.

Classification of Hydrogels Based on Their Source: A Review and Application in Stem Cell Regulation

NASA Astrophysics Data System (ADS)

Khansari, Maziyar M.; Sorokina, Lioudmila V.; Mukherjee, Prithviraj; Mukhtar, Farrukh; Shirdar, Mostafa Rezazadeh; Shahidi, Mahnaz; Shokuhfar, Tolou

2017-08-01

Stem cells are recognized by their self-renewal ability and can give rise to specialized progeny. Hydrogels are an established class of biomaterials with the ability to control stem cell fate via mechanotransduction. They can mimic various physiological conditions to influence the fate of stem cells and are an ideal platform to support stem cell regulation. This review article provides a summary of recent advances in the application of different classes of hydrogels based on their source (e.g., natural, synthetic, or hybrid). This classification is important because the chemistry of substrate affects stem cell differentiation and proliferation. Natural and synthetic hydrogels have been widely used in stem cell regulation. Nevertheless, they have limitations that necessitate a new class of material. Hybrid hydrogels obtained by manipulation of the natural and synthetic ones can potentially overcome these limitations and shape the future of research in application of hydrogels in stem cell regulation.

Xanthan and κ-carrageenan based alkaline hydrogels as electrolytes for Al/air batteries.

PubMed

Di Palma, T M; Migliardini, F; Caputo, D; Corbo, P

2017-02-10

Xanthan and κ-carrageenan were used to prepare alkaline hydrogels to be used as electrolytes in aluminium air primary batteries. Two pasty gels were obtained starting from xanthan and KOH solutions (1M and 8M), while only the 8M KOH solution permitted the formation of a stable, elastic and gumminess hydrogel with κ-carrageenan. Discharge tests, performed on three Al/air cells assembled with Al anodes, electrolyte gels and Pt based cathodes, evidenced that all hydrogels exhibited appreciable properties of Al ion conductivities, according to the following performance order: xanthan with KOH 1M

Synthesis and Characterization of Cellulose-Based Hydrogels to Be Used as Gel Electrolytes

PubMed Central

Navarra, Maria Assunta; Dal Bosco, Chiara; Serra Moreno, Judith; Vitucci, Francesco Maria; Paolone, Annalisa; Panero, Stefania

2015-01-01

Cellulose-based hydrogels, obtained by tuned, low-cost synthetic routes, are proposed as convenient gel electrolyte membranes. Hydrogels have been prepared from different types of cellulose by optimized solubilization and crosslinking steps. The obtained gel membranes have been characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical tests in order to investigate the crosslinking occurrence and modifications of cellulose resulting from the synthetic process, morphology of the hydrogels, their thermal stability, and viscoelastic-extensional properties, respectively. Hydrogels liquid uptake capability and ionic conductivity, derived from absorption of aqueous electrolytic solutions, have been evaluated, to assess the successful applicability of the proposed membranes as gel electrolytes for electrochemical devices. To this purpose, the redox behavior of electroactive species entrapped into the hydrogels has been investigated by cyclic voltammetry tests, revealing very high reversibility and ion diffusivity. PMID:26633528

Glycerophosphate-based chitosan thermosensitive hydrogels and their biomedical applications.

PubMed

Zhou, Hui Yun; Jiang, Ling Juan; Cao, Pei Pei; Li, Jun Bo; Chen, Xi Guang

2015-03-06

Chitosan is non-toxic, biocompatible and biodegradable polysaccharide composed of glucosamine and derived by deacetylation of chitin. Chitosan thermosensitive hydrogel has been developed to form a gel in situ, precluding the need for surgical implantation. In this review, the recent advances in chitosan thermosensitive hydrogels based on different glycerophosphate are summarized. The hydrogel is prepared with chitosan and β-glycerophosphate or αβ-glycerophosphate which is liquid at room temperature and transits into gel as temperature increases. The gelation mechanism may involve multiple interactions between chitosan, glycerophosphate, and water. The solution behavior, rheological and physicochemical properties, and gelation process of the hydrogel are affected not only by the molecule weight, deacetylation degree, and concentration of chitosan, but also by the kind and concentration of glycerophosphate. The properties and the three-dimensional networks of the hydrogel offer them wide applications in biomedical field including local drug delivery and tissue engineering. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enzymatic regulation of functional vascular networks using gelatin hydrogels

PubMed Central

Chuang, Chia-Hui; Lin, Ruei-Zeng; Tien, Han-Wen; Chu, Ya-Chun; Li, Yen-Cheng; Melero-Martin, Juan M.; Chen, Ying-Chieh

2015-01-01

To manufacture tissue engineering-based functional tissues, scaffold materials that can be sufficiently vascularized to mimic the functionality and complexity of native tissues are needed. Currently, vascular network bioengineering is largely carried out using natural hydrogels as embedding scaffolds, but most natural hydrogels have poor mechanical stability and durability, factors that critically limit their widespread use. In this study, we examined the suitability of gelatin-phenolic hydroxyl (gelatin-Ph) hydrogels that can be enzymatically crosslinked, allowing tuning of the storage modulus and the proteolytic degradation rate, for use as injectable hydrogels to support the human progenitor cell-based formation of a stable and mature vascular network. Porcine gelatin-Ph hydrogels were found to be cytocompatible with human blood-derived endothelial colony-forming cells and white adipose tissue-derived mesenchymal stem cells, resulting in >87% viability, and cell proliferation and spreading could be modulated by using hydrogels with different proteolytic degradability and stiffness. In addition, gelatin was extracted from mouse dermis and murine gelatin-Ph hydrogels were prepared. Importantly, implantation of human cell-laden porcine or murine gelatin-Ph hydrogels into immunodeficient mice resulted in the rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, the degree of enzymatic crosslinking of the gelatin-Ph hydrogels could be used to modulate cell behavior and the extent of vascular network formation in vivo. Our report details a technique for the synthesis of gelatin-Ph hydrogels from allogeneic or xenogeneic dermal skin and suggests that these hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues. PMID:25749296

On the role of hydrogel structure and degradation in controlling the transport of cell-secreted matrix molecules for engineered cartilage.

PubMed

Dhote, Valentin; Skaalure, Stacey; Akalp, Umut; Roberts, Justine; Bryant, Stephanie J; Vernerey, Franck J

2013-03-01

Damage to cartilage caused by injury or disease can lead to pain and loss of mobility, diminishing one's quality of life. Because cartilage has a limited capacity for self-repair, tissue engineering strategies, such as cells encapsulated in synthetic hydrogels, are being investigated as a means to restore the damaged cartilage. However, strategies to date are suboptimal in part because designing degradable hydrogels is complicated by structural and temporal complexities of the gel and evolving tissue along multiple length scales. To address this problem, this study proposes a multi-scale mechanical model using a triphasic formulation (solid, fluid, unbound matrix molecules) based on a single chondrocyte releasing extracellular matrix molecules within a degrading hydrogel. This model describes the key players (cells, proteoglycans, collagen) of the biological system within the hydrogel encompassing different length scales. Two mechanisms are included: temporal changes of bulk properties due to hydrogel degradation, and matrix transport. Numerical results demonstrate that the temporal change of bulk properties is a decisive factor in the diffusion of unbound matrix molecules through the hydrogel. Transport of matrix molecules in the hydrogel contributes both to the development of the pericellular matrix and the extracellular matrix and is dependent on the relative size of matrix molecules and the hydrogel mesh. The numerical results also demonstrate that osmotic pressure, which leads to changes in mesh size, is a key parameter for achieving a larger diffusivity for matrix molecules in the hydrogel. The numerical model is confirmed with experimental results of matrix synthesis by chondrocytes in biodegradable poly(ethylene glycol)-based hydrogels. This model may ultimately be used to predict key hydrogel design parameters towards achieving optimal cartilage growth. Copyright © 2012 Elsevier Ltd. All rights reserved.

On the role of hydrogel structure and degradation in controlling the transport of cell-secreted matrix molecules for engineered cartilage

PubMed Central

Dhote, Valentin; Skaalure, Stacey; Akalp, Umut; Roberts, Justine; Bryant, Stephanie J.; Vernerey, Franck J.

2012-01-01

Damage to cartilage caused by injury or disease can lead to pain and loss of mobility, diminishing one’s quality of life. Because cartilage has a limited capacity for self-repair, tissue engineering strategies, such as cells encapsulated in synthetic hydrogels, are being investigated as a means to restore the damaged cartilage. However, strategies to date are suboptimal in part because designing degradable hydrogels is complicated by structural and temporal complexities of the gel and evolving tissue along multiple length scales. To address this problem, this study proposes a multi-scale mechanical model using a triphasic formulation (solid, fluid, unbound matrix molecules) based on a single chondrocyte releasing extracellular matrix molecules within a degrading hydrogel. This model describes the key players (cells, proteoglycans, collagen) of the biological system within the hydrogel encompassing different length scales. Two mechanisms are included: temporal changes of bulk properties due to hydrogel degradation, and matrix transport. Numerical results demonstrate that the temporal change of bulk properties is a decisive factor in the diffusion of unbound matrix molecules through the hydrogel. Transport of matrix molecules in the hydrogel contributes both to the development of the pericellular matrix and the extracellular matrix and is dependent on the relative size of matrix molecules and the hydrogel mesh. The numerical results also demonstrate that osmotic pressure, which leads to changes in mesh size, is a key parameter for achieving a larger diffusivity for matrix molecules in the hydrogel. The numerical model is confirmed with experimental results of matrix synthesis by chondrocytes in biodegradable poly(ethylene glycol)-based hydrogels. This model may ultimately be used to predict key hydrogel design parameters towards achieving optimal cartilage growth. PMID:23276516

Co-delivery of evodiamine and rutaecarpine in a microemulsion-based hyaluronic acid hydrogel for enhanced analgesic effects on mouse pain models.

PubMed

Zhang, Yong-Tai; Li, Zhe; Zhang, Kai; Zhang, Hong-Yu; He, Ze-Hui; Xia, Qing; Zhao, Ji-Hui; Feng, Nian-Ping

2017-08-07

The aim of this study was to improve the analgesic effect of evodiamine and rutaecarpine, using a microemulsion-based hydrogel (ME-Gel) as the transdermal co-delivery vehicle, and to assess hyaluronic acid as a hydrogel matrix for microemulsion entrapment. A microemulsion was formulated with ethyl oleate as the oil core to improve the solubility of the alkaloids and was loaded into a hyaluronic acid-structured hydrogel. Permeation-enhancing effects of the microemulsion enabled evodiamine and rutaecarpine in ME-Gel to achieve 2.60- and 2.59-fold higher transdermal fluxes compared with hydrogel control (p<0.01). The hyaluronic acid hydrogel-containing microemulsion exhibited good skin biocompatibility, whereas effective ME-Gel co-delivery of evodiamine and rutaecarpine through the skin enhanced the analgesic effect in mouse pain models compared with hydrogel. Notably, evodiamine and rutaecarpine administered using ME-Gel effectively down-regulated serum levels of prostaglandin E 2 , interleukin 6, and tumor necrosis factor α in formaldehyde-induced mouse pain models, possibly reflecting the improved transdermal permeability of ME-Gel co-delivered evodiamine and rutaecarpine, particularly with hyaluronic acid as the hydrogel matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

Short-peptide-based molecular hydrogels: novel gelation strategies and applications for tissue engineering and drug delivery

NASA Astrophysics Data System (ADS)

Wang, Huaimin; Yang, Zhimou

2012-08-01

Molecular hydrogels hold big potential for tissue engineering and controlled drug delivery. Our lab focuses on short-peptide-based molecular hydrogels formed by biocompatible methods and their applications in tissue engineering (especially, 3D cell culture) and controlled drug delivery. This feature article firstly describes our recent progresses of the development of novel methods to form hydrogels, including the strategy of disulfide bond reduction and assistance with specific protein-peptide interactions. We then introduce the applications of our hydrogels in fields of controlled stem cell differentiation, cell culture, surface modifications of polyester materials by molecular self-assembly, and anti-degradation of recombinant complex proteins. A novel molecular hydrogel system of hydrophobic compounds that are only formed by hydrolysis processes was also included in this article. The hydrogels of hydrophobic compounds, especially those of hydrophobic therapeutic agents, may be developed into a carrier-free delivery system for long term delivery of therapeutic agents. With the efforts in this field, we believe that molecular hydrogels formed by short peptides and hydrophobic therapeutic agents can be practically applied for 3D cell culture and long term drug delivery in near future, respectively.

Mechanically Robust 3D Nanostructure Chitosan-Based Hydrogels with Autonomic Self-Healing Properties.

PubMed

Karimi, Ali Reza; Khodadadi, Azam

2016-10-12

Fabrication of hydrogels based on chitosan (CS) with superb self-healing behavior and high mechanical and electrical properties has become a challenging and fascinating topic. Most of the conventional hydrogels lack these properties at the same time. Our objectives in this research were to synthesize, characterize, and evaluate the general properties of chitosan covalently cross-linked with zinc phthalocyanine tetra-aldehyde (ZnPcTa) framework. Our hope was to access an unprecedented self-healable three-dimensional (3D) nanostructure that would harvest the superior mechanical and electrical properties associated with chitosan. The properties of cross-linker such as the structure, steric effect, and rigidity of the molecule played important roles in determining the microstructure and properties of the resulting hydrogels. The tetra-functionalized phthalocyanines favor a dynamic Schiff-base linkage with chitosan to form a 3D porous nanostructure. Based on this strategy, the self-healing ability, as demonstrated by rheological recovery and macroscopic and microscopic observations, is introduced through dynamic covalent Schiff-base linkage between NH 2 groups in CS and benzaldehyde groups at cross-linker ends. The hydrogel was characterized using FT-IR, NMR, UV/vis, and rheological measurements. In addition, cryogenic scanning electron microscopy (cryo-SEM) was employed as a technique to visualize the internal morphology of the hydrogels. Study of the surface morphology of the hydrogel showed a 3D porous nanostructure with uniform morphology. Furthermore, incorporating the conductive nanofillers, such as carbon nanotubes (CNTs), into the structure can modulate the mechanical and electrical properties of the obtained hydrogels. Interestingly, these hydrogel nanocomposites proved to have very good film-forming properties, high modulus and strength, acceptable electrical conductivity, and excellent self-healing properties at neutral pH. Such properties can be finely tuned through variation of the cross-linker and CNT concentration, and as a result these structures are promising candidates for potential applications in various fields of research.

Weak Bond-Based Injectable and Stimuli Responsive Hydrogels for Biomedical Applications

PubMed Central

Ding, Xiaochu; Wang, Yadong

2017-01-01

Here we define hydrogels crosslinked by weak bonds as physical hydrogels. They possess unique features including reversible bonding, shear thinning and stimuli-responsiveness. Unlike covalently crosslinked hydrogels, physical hydrogels do not require triggers to initiate chemical reactions for in situ gelation. The drug can be fully loaded in a pre-formed hydrogel for delivery with minimal cargo leakage during injection. These benefits make physical hydrogels useful as delivery vehicles for applications in biomedical engineering. This review focuses on recent advances of physical hydrogels crosslinked by weak bonds: hydrogen bonds, ionic interactions, host-guest chemistry, hydrophobic interactions, coordination bonds and π-π stacking interactions. Understanding the principles and the state of the art of gels with these dynamic bonds may give rise to breakthroughs in many biomedical research areas including drug delivery and tissue engineering. PMID:29062484

X-ray Phase Contrast Allows Three Dimensional, Quantitative Imaging of Hydrogel Implants

PubMed Central

Appel, Alyssa A.; Larson, Jeffery C.; Jiang, Bin; Zhong, Zhong; Anastasio, Mark A.; Brey, Eric M.

2015-01-01

Three dimensional imaging techniques are needed for the evaluation and assessment of biomaterials used for tissue engineering and drug delivery applications. Hydrogels are a particularly popular class of materials for medical applications but are difficult to image in tissue using most available imaging modalities. Imaging techniques based on X-ray Phase Contrast (XPC) have shown promise for tissue engineering applications due to their ability to provide image contrast based on multiple X-ray properties. In this manuscript, we investigate the use of XPC for imaging a model hydrogel and soft tissue structure. Porous fibrin loaded poly(ethylene glycol) hydrogels were synthesized and implanted in a rodent subcutaneous model. Samples were explanted and imaged with an analyzer-based XPC technique and processed and stained for histology for comparison. Both hydrogel and soft tissues structures could be identified in XPC images. Structure in skeletal muscle adjacent could be visualized and invading fibrovascular tissue could be quantified. There were no differences between invading tissue measurements from XPC and the gold-standard histology. These results provide evidence of the significant potential of techniques based on XPC for 3D imaging of hydrogel structure and local tissue response. PMID:26487123

Bio-functionalized silk hydrogel microfluidic systems.

PubMed

Zhao, Siwei; Chen, Ying; Partlow, Benjamin P; Golding, Anne S; Tseng, Peter; Coburn, Jeannine; Applegate, Matthew B; Moreau, Jodie E; Omenetto, Fiorenzo G; Kaplan, David L

2016-07-01

Bio-functionalized microfluidic systems were developed based on a silk protein hydrogel elastomeric materials. A facile multilayer fabrication method using gelatin sacrificial molding and layer-by-layer assembly was implemented to construct interconnected, three dimensional (3D) microchannel networks in silk hydrogels at 100 μm minimum feature resolution. Mechanically activated valves were implemented to demonstrate pneumatic control of microflow. The silk hydrogel microfluidics exhibit controllable mechanical properties, long-term stability in various environmental conditions, tunable in vitro and in vivo degradability in addition to optical transparency, providing unique features for cell/tissue-related applications than conventional polydimethylsiloxane (PDMS) and existing hydrogel-based microfluidic options. As demonstrated in the work here, the all aqueous-based fabrication process at ambient conditions enabled the incorporation of active biological substances in the bulk phase of these new silk microfluidic systems during device fabrication, including enzymes and living cells, which are able to interact with the fluid flow in the microchannels. These silk hydrogel-based microfluidic systems offer new opportunities in engineering active diagnostic devices, tissues and organs that could be integrated in vivo, and for on-chip cell sensing systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

X-ray Phase Contrast Allows Three Dimensional, Quantitative Imaging of Hydrogel Implants

DOE PAGES

Appel, Alyssa A.; Larson, Jeffrey C.; Jiang, Bin; ...

2015-10-20

Three dimensional imaging techniques are needed for the evaluation and assessment of biomaterials used for tissue engineering and drug delivery applications. Hydrogels are a particularly popular class of materials for medical applications but are difficult to image in tissue using most available imaging modalities. Imaging techniques based on X-ray Phase Contrast (XPC) have shown promise for tissue engineering applications due to their ability to provide image contrast based on multiple X-ray properties. In this manuscript we describe results using XPC to image a model hydrogel and soft tissue structure. Porous fibrin loaded poly(ethylene glycol) hydrogels were synthesized and implanted inmore » a rodent subcutaneous model. Samples were explanted and imaged with an analyzer-based XPC technique and processed and stained for histology for comparison. Both hydrogel and soft tissues structures could be identified in XPC images. Structure in skeletal muscle adjacent could be visualized and invading fibrovascular tissue could be quantified. In quantitative results, there were no differences between XPC and the gold-standard histological measurements. These results provide evidence of the significant potential of techniques based on XPC for 3D imaging of hydrogel structure and local tissue response.« less

High performance polymer chemical hydrogel-based electrode binder materials for direct borohydride fuel cells

NASA Astrophysics Data System (ADS)

Choudhury, Nurul A.; Ma, Jia; Sahai, Yogeshwar; Buchheit, Rudolph G.

Novel, cost-effective, high-performance, and environment-friendly electrode binders, comprising polyvinyl alcohol chemical hydrogel (PCH) and chitosan chemical hydrogel (CCH), are reported for direct borohydride fuel cells (DBFCs). PCH and CCH binders-based electrodes have been fabricated using a novel, simple, cost-effective, time-effective, and environmentally benign technique. Morphologies and electrochemical performance in DBFCs of the chemical hydrogel binder-based electrodes have been compared with those of Nafion ® binder-based electrodes. Relationships between the performance of binders in DBFCs with structural features of the polymers and the polymer-based chemical hydrogels are discussed. The CCH binder exhibited better performance than a Nafion ® binder whereas the PCH binder exhibited comparable performance to Nafion ® in DBFCs operating at elevated cell temperatures. The better performance of CCH binder at higher operating cell temperatures has been ascribed to the hydrophilic nature and water retention characteristics of chitosan. DBFCs employing CCH binder-based electrodes and a Nafion ®-117 membrane as an electrolyte exhibited a maximum peak power density of about 589 mW cm -2 at 70 °C.

Biocompatible nanomaterials based on dendrimers, hydrogels and hydrogel nanocomposites for use in biomedicine

NASA Astrophysics Data System (ADS)

Khoa Nguyen, Cuu; Quyen Tran, Ngoc; Phuong Nguyen, Thi; Hai Nguyen, Dai

2017-03-01

Over the past decades, biopolymer-based nanomaterials have been developed to overcome the limitations of other macro- and micro- synthetic materials as well as the ever increasing demand for the new materials in nanotechnology, biotechnology, biomedicine and others. Owning to their high stability, biodegradability, low toxicity, and biocompatibility, biopolymer-based nanomaterials hold great promise for various biomedical applications. The pursuit of this review is to briefly describe our recent studies regarding biocompatible biopolymer-based nanomaterials, particularly in the form of dendrimers, hydrogels, and hydrogel composites along with the synthetic and modification approaches for the utilization in drug delivery, tissue engineering, and biomedical implants. Moreover, in vitro and in vivo studies for the toxicity evaluation are also discussed.

Electroactive SWNT/PEGDA hybrid hydrogel coating for bio-electrode interface.

PubMed

He, Lei; Lin, Demeng; Wang, Yanping; Xiao, Yinghong; Che, Jianfei

2011-10-15

Electric interface between neural tissue and electrode plays a significant role in the development of implanted devices for continuous monitoring and functional stimulation of central nervous system in terms of electroactivity, biocompatibility and long-term stability. To engineer an interface that possesses these merits, a polymeric hydrogel based on poly(ethylene glycol) diacrylate (PEGDA) and single-walled carbon nanotubes (SWNTs) were employed to fabricate a hybrid hydrogel via covalent anchoring strategy, i.e., self-assembly of cysteamine (Cys) followed by Michael addition between Cys and PEGDA. XPS characterization proves that the Cys molecules are linked to gold surface via the strong S-Au bond and that the PEGDA macromers are covalently bonded to Cys. FTIR spectra indicate the formation of hybrid hydrogel coating during photopolymerization. Electrochemical measurements using cyclic voltammetry (CV) and impedance spectrum clearly show the enhancement of electric properties to the hydrogel by the SWNTs. The charge transfer of the hybrid hydrogel-based electrode is quasi-reversible and charge transfer resistance decreases to the tenth of that of the pure hydrogel due to electron hopping along the SWNTs. Additionally, this hybrid hydrogel provides a favorable biomimetic microenvironment for cell attachment and growth due to its inherent biocompatibility. Combination of these merits yields hybrid hydrogels that can be good candidates for application to biosensors and biomedical devices. More importantly, the hybrid hydrogel coatings fabricated via the current strategy have good adhesion to the electrode substrate which is highly desired for chronically implantable devices. Copyright © 2011 Elsevier B.V. All rights reserved.

In Vivo Imaging of the Stability and Sustained Cargo Release of an Injectable Amphipathic Peptide-Based Hydrogel.

PubMed

Oyen, Edith; Martin, Charlotte; Caveliers, Vicky; Madder, Annemieke; Van Mele, Bruno; Hoogenboom, Richard; Hernot, Sophie; Ballet, Steven

2017-03-13

Hydrogels are promising materials for biomedical applications such as tissue engineering and controlled drug release. In the past two decades, the peptide hydrogel subclass has attracted an increasing level of interest from the scientific community because of its numerous advantages, such as biocompatibility, biodegradability, and, most importantly, injectability. Here, we report on a hydrogel consisting of the amphipathic hexapeptide H-FEFQFK-NH 2 , which has previously shown promising in vivo properties in terms of releasing morphine. In this study, the release of a small molecule, a peptide, and a protein cargo as representatives of the three major drug classes is directly visualized by in vivo fluorescence and nuclear imaging. In addition, the in vivo stability of the peptide hydrogel system is investigated through the use of a radiolabeled hydrogelator sequence. Although it is shown that the hydrogel remains present for several days, the largest decrease in volume takes place within the first 12 h of subcutaneous injection, which is also the time frame wherein the cargos are released. Compared to the situation in which the cargos are injected in solution, a prolonged release profile is observed up to 12 h, showing the potential of our hydrogel system as a scaffold for controlled drug delivery. Importantly, this study elucidates the release mechanism of the peptide hydrogel system that seems to be based on erosion of the hydrogel providing a generally applicable controlled release platform for small molecule, peptide, and protein drugs.

Three-dimensional bioprinting of complex cell laden alginate hydrogel structures.

PubMed

Tabriz, Atabak Ghanizadeh; Hermida, Miguel A; Leslie, Nicholas R; Shu, Wenmiao

2015-12-21

Different bioprinting techniques have been used to produce cell-laden alginate hydrogel structures, however these approaches have been limited to 2D or simple three-dimension (3D) structures. In this study, a new extrusion based bioprinting technique was developed to produce more complex alginate hydrogel structures. This was achieved by dividing the alginate hydrogel cross-linking process into three stages: primary calcium ion cross-linking for printability of the gel, secondary calcium cross-linking for rigidity of the alginate hydrogel immediately after printing and tertiary barium ion cross-linking for long-term stability of the alginate hydrogel in culture medium. Simple 3D structures including tubes were first printed to ensure the feasibility of the bioprinting technique and then complex 3D structures such as branched vascular structures were successfully printed. The static stiffness of the alginate hydrogel after printing was 20.18 ± 1.62 KPa which was rigid enough to sustain the integrity of the complex 3D alginate hydrogel structure during the printing. The addition of 60 mM barium chloride was found to significantly extend the stability of the cross-linked alginate hydrogel from 3 d to beyond 11 d without compromising the cellular viability. The results based on cell bioprinting suggested that viability of U87-MG cells was 93 ± 0.9% immediately after bioprinting and cell viability maintained above 88% ± 4.3% in the alginate hydrogel over the period of 11 d.

Sundew-Inspired Adhesive Hydrogels Combined with Adipose-Derived Stem Cells for Wound Healing

PubMed Central

Sun, Leming; Huang, Yujian; Bian, Zehua; Petrosino, Jennifer; Fan, Zhen; Wang, Yongzhong; Park, Ki Ho; Yue, Tao; Schmidt, Michael; Galster, Scott; Ma, Jianjie; Zhu, Hua; Zhang, Mingjun

2016-01-01

The potential to harness the unique physical, chemical, and biological properties of the sundew (Drosera) plant’s adhesive hydrogels has long intrigued researchers searching for novel wound-healing applications. However, the ability to collect sufficient quantities of the sundew plant’s adhesive hydrogels is problematic and has eclipsed their therapeutic promise. Inspired by these natural hydrogels, we asked if sundew-inspired adhesive hydrogels could overcome the drawbacks associated with natural sundew hydrogels and be used in combination with stem-cell-based therapy to enhance wound-healing therapeutics. Using a bioinspired approach, we synthesized adhesive hydrogels comprised of sodium alginate, gum arabic, and calcium ions to mimic the properties of the natural sundew-derived adhesive hydrogels. We then characterized and showed that these sundew-inspired hydrogels promote wound healing through their superior adhesive strength, nanostructure, and resistance to shearing when compared to other hydrogels in vitro. In vivo, sundew-inspired hydrogels promoted a “suturing” effect to wound sites, which was demonstrated by enhanced wound closure following topical application of the hydrogels. In combination with mouse adipose-derived stem cells (ADSCs) and compared to other therapeutic biomaterials, the sundew-inspired hydrogels demonstrated superior wound-healing capabilities. Collectively, our studies show that sundew-inspired hydrogels contain ideal properties that promote wound healing and suggest that sundew-inspired-ADSCs combination therapy is an efficacious approach for treating wounds without eliciting noticeable toxicity or inflammation. PMID:26731614

Sundew-Inspired Adhesive Hydrogels Combined with Adipose-Derived Stem Cells for Wound Healing.

PubMed

Sun, Leming; Huang, Yujian; Bian, Zehua; Petrosino, Jennifer; Fan, Zhen; Wang, Yongzhong; Park, Ki Ho; Yue, Tao; Schmidt, Michael; Galster, Scott; Ma, Jianjie; Zhu, Hua; Zhang, Mingjun

2016-01-27

The potential to harness the unique physical, chemical, and biological properties of the sundew (Drosera) plant's adhesive hydrogels has long intrigued researchers searching for novel wound-healing applications. However, the ability to collect sufficient quantities of the sundew plant's adhesive hydrogels is problematic and has eclipsed their therapeutic promise. Inspired by these natural hydrogels, we asked if sundew-inspired adhesive hydrogels could overcome the drawbacks associated with natural sundew hydrogels and be used in combination with stem-cell-based therapy to enhance wound-healing therapeutics. Using a bioinspired approach, we synthesized adhesive hydrogels comprised of sodium alginate, gum arabic, and calcium ions to mimic the properties of the natural sundew-derived adhesive hydrogels. We then characterized and showed that these sundew-inspired hydrogels promote wound healing through their superior adhesive strength, nanostructure, and resistance to shearing when compared to other hydrogels in vitro. In vivo, sundew-inspired hydrogels promoted a "suturing" effect to wound sites, which was demonstrated by enhanced wound closure following topical application of the hydrogels. In combination with mouse adipose-derived stem cells (ADSCs) and compared to other therapeutic biomaterials, the sundew-inspired hydrogels demonstrated superior wound-healing capabilities. Collectively, our studies show that sundew-inspired hydrogels contain ideal properties that promote wound healing and suggest that sundew-inspired-ADSCs combination therapy is an efficacious approach for treating wounds without eliciting noticeable toxicity or inflammation.

Strain rate dependent hyperelastic stress-stretch behavior of a silica nanoparticle reinforced poly (ethylene glycol) diacrylate nanocomposite hydrogel.

PubMed

Zhan, Yuexing; Pan, Yihui; Chen, Bing; Lu, Jian; Zhong, Zheng; Niu, Xinrui

2017-11-01

Poly (ethylene glycol) diacrylate (PEGDA) derivatives are important biomedical materials. PEGDA based hydrogels have emerged as one of the popular regenerative orthopedic materials. This work aims to study the mechanical behavior of a PEGDA based silica nanoparticle (NP) reinforced nanocomposite (NC) hydrogel at physiological strain rates. The work combines materials fabrication, mechanical experiments, mathematical modeling and structural analysis. The strain rate dependent stress-stretch behaviors were observed, analyzed and quantified. Visco-hyperelasticity was identified as the deformation mechanism of the nano-silica/PEGDA NC hydrogel. NPs showed significant effect on both initial shear modulus and viscoelastic materials properties. A structure-based quasi-linear viscoelastic (QLV) model was constructed and capable to describe the visco-hyperelastic stress-stretch behavior of the NC hydrogel. A group of unified material parameters was extracted by the model from the stress-stretch curves obtained at different strain rates. Visco-hyperelastic behavior of NP/polymer interphase was not only identified but also quantified. The work could provide guidance to the structural design of next-generation NC hydrogel. Copyright © 2017. Published by Elsevier Ltd.

Multifunctional Tannic Acid/Silver Nanoparticle-Based Mucoadhesive Hydrogel for Improved Local Treatment of HSV Infection: In Vitro and In Vivo Studies

PubMed Central

Szymańska, Emilia; Orłowski, Piotr; Tomaszewska, Emilia; Bąska, Piotr; Grobelny, Jarosław; Basa, Anna; Krzyżowska, Małgorzata

2018-01-01

Mucoadhesive gelling systems with tannic acid modified silver nanoparticles were developed for effective treatment of herpes virus infections. To increase nanoparticle residence time after local application, semi solid formulations designed from generally regarded as safe (GRAS) excipients were investigated for their rheological and mechanical properties followed with ex vivo mucoadhesive behavior to the porcine vaginal mucosa. Particular effort was made to evaluate the activity of nanoparticle-based hydrogels toward herpes simplex virus (HSV) type 1 and 2 infection in vitro in immortal human keratinocyte cell line and in vivo using murine model of HSV-2 genital infection. The effect of infectivity was determined by real time quantitative polymerase chain reaction, plaque assay, inactivation, attachment, penetration and cell-to-cell assessments. All analyzed nanoparticle-based hydrogels exhibited pseudoplastic and thixotropic properties. Viscosity and mechanical measurements of hydrogels were found to correlate with the mucoadhesive properties. The results confirmed the ability of nanoparticle-based hydrogels to affect viral attachment, impede penetration and cell-to-cell transmission, although profound differences in the activity evoked by tested preparations toward HSV-1 and HSV-2 were noted. In addition, these findings demonstrated the in vivo potential of tannic acid modified silver nanoparticle-based hydrogels for vaginal treatment of HSV-2 genital infection. PMID:29382085

Injectable Absorbable Ocular Inserts for Controlled Drug Delivery

DTIC Science & Technology

1997-07-01

conjunctiva for prolonged delivery of drugs to the anterior region of the eye (Gwon & Meadows, 1992). The dosage system was an elliptically shaped unit...1979) have reviewed many other gel formers which are available for preparing pharmaceutical gels. A.3.4.1. Hydrogels -- Hydrogels are materials which...denoted as hydrogels (or aquagels). Hydrogels based on crosslinked polymeric chains of methoxy poly(ethylene glycol) monomethacrylate having variable

Nanocomposite hydrogels stabilized by self-assembled multivalent bisphosphonate-magnesium nanoparticles mediate sustained release of magnesium ion and promote in-situ bone regeneration.

PubMed

Zhang, Kunyu; Lin, Sien; Feng, Qian; Dong, Chaoqun; Yang, Yanhua; Li, Gang; Bian, Liming

2017-12-01

Hydrogels are appealing biomaterials for applications in regenerative medicine due to their tunable physical and bioactive properties. Meanwhile, therapeutic metal ions, such as magnesium ion (Mg 2+ ), not only regulate the cellular behaviors but also stimulate local bone formation and healing. However, the effective delivery and tailored release of Mg 2+ remains a challenge, with few reports on hydrogels being used for Mg 2+ delivery. Bisphosphonate exhibits a variety of specific bioactivities and excellent binding affinity to multivalent cations such as Mg 2+ . Herein, we describe a nanocomposite hydrogel based on hyaluronic acid and self-assembled bisphosphonate-magnesium (BP-Mg) nanoparticles. These nanoparticles bearing acrylate groups on the surface not only function as effective multivalent crosslinkers to strengthen the hydrogel network structure, but also promote the mineralization of hydrogels and mediate sustained release of Mg 2+ . The released Mg 2+ ions facilitate stem cell adhesion and spreading on the hydrogel substrates in the absence of cell adhesion ligands, and promote osteogenesis of the seeded hMSCs in vitro. Furthermore, the acellular porous hydrogels alone can support in situ bone regeneration without using exogenous cells and inductive agents, thereby greatly simplifying the approaches of bone regeneration therapy. In this study, we developed a novel bioactive nanocomposite hydrogel based on hyaluronic acid and self-assembled bisphosphonate-magnesium (BP-Mg) nanoparticles. Such hydrogels are stabilized by the multivalent crosslinking domains formed by the aggregation of Ac-BP-Mg NPs, and therefore show enhanced mechanical properties, improved capacity for mineralization, and controlled release kinetics of Mg 2+ . Moreover, the released Mg 2+ can enhance cell adhesion and spreading, and further promote the osteogenic differentiation of hMSCs. Owing to these unique properties, these acellular hydrogels alone can well facilitate the in vivo bone regeneration at the intended sites. We believe that the strategy reported in this work opens up a new route to develop biopolymer-based nanocomposite hydrogels with enhanced physical and biological functionalities for regenerative medicine. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering

PubMed Central

Cochis, Andrea; Sorrentino, Rita; Grassi, Federico; Leigheb, Massimiliano; Farè, Silvia

2018-01-01

A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na2SO4 and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues. PMID:29642573

SAM-based Cell Transfer to Photopatterned Hydrogels for Microengineering Vascular-Like Structures

PubMed Central

Sadr, Nasser; Zhu, Mojun; Osaki, Tatsuya; Kakegawa, Takahiro; Yang, Yunzhi; Moretti, Matteo; Fukuda, Junji; Khademhosseini, Ali

2011-01-01

A major challenge in tissue engineering is to reproduce the native 3D microvascular architecture fundamental for in vivo functions. Current approaches still lack a network of perfusable vessels with native 3D structural organization. Here we present a new method combining self-assembled monolayer (SAM)-based cell transfer and gelatin methacrylate hydrogel photopatterning techniques for microengineering vascular structures. Human umbilical vein cell (HUVEC) transfer from oligopeptide SAM-coated surfaces to the hydrogel revealed two SAM desorption mechanisms: photoinduced and electrochemically triggered. The former, occurs concomitantly to hydrogel photocrosslinking, and resulted in efficient (>97%) monolayer transfer. The latter, prompted by additional potential application, preserved cell morphology and maintained high transfer efficiency of VE-cadherin positive monolayers over longer culture periods. This approach was also applied to transfer HUVECs to 3D geometrically defined vascular-like structures in hydrogels, which were then maintained in perfusion culture for 15 days. As a step toward more complex constructs, a cell-laden hydrogel layer was photopatterned around the endothelialized channel to mimic the vascular smooth muscle structure of distal arterioles. This study shows that the coupling of the SAM-based cell transfer and hydrogel photocrosslinking could potentially open up new avenues in engineering more complex, vascularized tissue constructs for regenerative medicine and tissue engineering applications. PMID:21802723

Tailoring drug release rates in hydrogel-based therapeutic delivery applications using graphene oxide

PubMed Central

Zhi, Z. L.; Craster, R. V.

2018-01-01

Graphene oxide (GO) is increasingly used for controlling mass diffusion in hydrogel-based drug delivery applications. On the macro-scale, the density of GO in the hydrogel is a critical parameter for modulating drug release. Here, we investigate the diffusion of a peptide drug through a network of GO membranes and GO-embedded hydrogels, modelled as porous matrices resembling both laminated and ‘house of cards’ structures. Our experiments use a therapeutic peptide and show a tunable nonlinear dependence of the peptide concentration upon time. We establish models using numerical simulations with a diffusion equation accounting for the photo-thermal degradation of fluorophores and an effective percolation model to simulate the experimental data. The modelling yields an interpretation of the control of drug diffusion through GO membranes, which is extended to the diffusion of the peptide in GO-embedded agarose hydrogels. Varying the density of micron-sized GO flakes allows for fine control of the drug diffusion. We further show that both GO density and size influence the drug release rate. The ability to tune the density of hydrogel-like GO membranes to control drug release rates has exciting implications to offer guidelines for tailoring drug release rates in hydrogel-based therapeutic delivery applications. PMID:29445040

Injectable dextran hydrogels fabricated by metal-free click chemistry for cartilage tissue engineering.

PubMed

Wang, Xiaoyu; Li, Zihan; Shi, Ting; Zhao, Peng; An, Kangkang; Lin, Chao; Liu, Hongwei

2017-04-01

Injectable dextran-based hydrogels were prepared for the first time by bioorthogonal click chemistry for cartilage tissue engineering. Click-crosslinked injectable hydrogels based on cyto-compatible dextran (Mw=10kDa) were successfully fabricated under physiological conditions by metal-free alkyne-azide cycloaddition (click) reaction between azadibenzocyclooctyne-modified dextran (Dex-ADIBO) and azide-modified dextran (Dex-N 3 ). Gelation time of these dextran hydrogels could be regulated in the range of approximately 1.1 to 10.2min, depending on the polymer concentrations (5% or 10%) and ADIBO substitution degree (DS, 5 or 10) of Dex-ADIBO. Rheological analysis indicated that the dextran hydrogels were elastic and had storage moduli from 2.1 to 6.0kPa with increasing DS of ADIBO from 5 to 10. The in vitro tests revealed that the dextran hydrogel crosslinked from Dex-ADIBO DS 10 and Dex-N 3 DS 10 at a polymer concentration of 10% could support high viability of individual rabbit chondrocytes and the chondrocyte spheroids encapsulated in the hydrogel over 21days. Individual chondrocytes and chondrocyte spheroids in the hydrogel could produce cartilage matrices such as collagen and glycosaminoglycans. However, the chondrocyte spheroids produced a higher content of matrices than individual chondrocytes. This study indicates that metal-free click chemistry is effective to produce injectable dextran hydrogels for cartilage tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of Hydrogel in Reconstruction Surgery: Hydrogel/Fat Graft Complex Filler for Volume Reconstruction in Critical Sized Muscle Defects.

PubMed

Lui, Y F; Ip, W Y

2016-01-01

Autogenic fat graft usually suffers from degeneration and volume shrinkage in volume reconstruction applications. How to maintain graft viability and graft volume is an essential consideration in reconstruction therapies. In this presented investigation, a new fat graft transplantation method was developed aiming to improve long term graft viability and volume reconstruction effect by incorporation of hydrogel. The harvested fat graft is dissociated into small fragments and incorporated into a collagen based hydrogel to form a hydrogel/fat graft complex for volume reconstruction purpose. In vitro results indicate that the collagen based hydrogel can significantly improve the survivability of cells inside isolated graft. In a 6-month investigation on artificial created defect model, this hydrogel/fat graft complex filler has demonstrated the ability of promoting fat pad formation inside the targeted defect area. The newly generated fat pad can cover the whole defect and restore its original dimension in 6-month time point. Compared to simple fat transplantation, this hydrogel/fat graft complex system provides much improvement on long term volume restoration effect against degeneration and volume shrinkage. One notable effect is that there is continuous proliferation of adipose tissue throughout the 6-month period. In summary, the hydrogel/fat graft system presented in this investigation demonstrated a better and more significant effect on volume reconstruction in large sized volume defect than simple fat transplantation.

Writing with Fluid: Structuring Hydrogels with Micrometer Precision by AFM in Combination with Nanofluidics.

PubMed

Helfricht, Nicolas; Mark, Andreas; Behr, Marina; Bernet, Andreas; Schmidt, Hans-Werner; Papastavrou, Georg

2017-08-01

Hydrogels have many applications in biomedical surface modification and tissue engineering. However, the structuring of hydrogels after their formation represents still a major challenge, in particular due to their softness. Here, a novel approach is presented that is based on the combination of atomic force microscopy (AFM) and nanofluidics, also referred to as FluidFM technology. Its applicability is demonstrated for supramolecular hydrogel films that are prepared from low-molecular weight hydrogelators, such as derivates of 1,3,5-benzene tricarboxamides (BTAs). BTA films can be dissolved selectively by ejecting alkaline solution through the aperture of a hollow AFM-cantilever connected to a nanofluidic controller. The AFM-based force control is essential in preventing mechanical destruction of the hydrogels. The resulting "chemical writing" process is studied in detail and the influence of various parameters, such as applied pressure and time, is validated. It is demonstrated that the achievable structuring precision is primarily limited by diffusion and the aperture dimensions. Recently, various additive techniques have been presented to pattern hydrogels. The here-presented subtractive approach can not only be applied to structure hydrogels from the large class of reversibly formed gels with superior resolution but would also allow for the selective loading of the hydrogels with active substances or nanoparticles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

PubMed

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

2014-07-17

A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study on temperature and near-infrared driving characteristics of hydrogel actuator fabricated via molding and 3D printing.

PubMed

Zhao, Qian; Liang, Yunhong; Ren, Lei; Qiu, Feng; Zhang, Zhihui; Ren, Luquan

2018-02-01

A hydrogel material system which was fit for molding and 3D printing was developed to fabricate bilayer hydrogel actuators with controllable temperature and near infrared laser responses. Polymerization on interface boundary of layered structure enhanced the bonding strength of hydrogel actuators. By utilizing anisotropic of microstructure along with thickness direction, bilayer hydrogel actuators fabricated via molding realized intelligent bending/shrinking responses, which guided the preparation of hydrogel ink for 3D printing. In-situ free radical polymerization under vacuum realized the solidification of printed hydrogel actuators with graphene oxide. Based on anisotropic swelling/deswelling behaviors of precise structure fabricated via 3D printing, the printed bilayer hydrogel actuators achieved temperature and near infrared laser responsive deformation. Changes of programmable printing path effectively resulted in corresponding deformation patterns. Combination of advantages of molding and 3D printing can promote the design and fabrication of hydrogel actuators with high mechanical strength, response speed and deformation ability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dextran hydrogels by crosslinking with amino acid diamines and their viscoelastic properties.

PubMed

O'Connor, Naphtali A; Jitianu, Mihaela; Nunez, Greisly; Picard, Quentin; Wong, Madeline; Akpatsu, David; Negrin, Adam; Gharbaran, Rajendra; Lugo, Daniel; Shaker, Sundus; Jitianu, Andrei; Redenti, Stephen

2018-05-01

Amine functionalized polysaccharide hydrogels such as those based on chitosan are widely examined as biomaterials. Here we set out to develop a facile procedure for developing such hydrogels by crosslinking dextran with amino acid diamines. The dextran-amino acid gels were formed by the addition of the amino acid diamines to a dextran and epichlorohydrin solution once it became homogeneous. This was demonstrated with three amino acid diamines, lysine, lysine methyl ester, and cystine dimethyl ester. Hydrogel networks with albumin entrapped were also demonstrated. These hydrogels were characterized by FTIR, SEM, rotational rheometry, swelling studies and cell biocompatibility analysis. These hydrogels showed the unexpected pH-responsive behavior of greater swelling at more basic pH, similar to that of an anionic hydrogel. This is uncharacteristic for amine functionalized gels as they typically exhibit cationic hydrogel behavior. All hydrogels showed similar biocompatibility to that of dextran crosslinked without amino acids. Copyright © 2018 Elsevier B.V. All rights reserved.

25th Anniversary Article: Rational Design and Applications of Hydrogels in Regenerative Medicine

PubMed Central

Annabi, Nasim; Tamayol, Ali; Uquillas, Jorge Alfredo; Akbari, Mohsen; Bertassoni, Luiz E.; Cha, Chaenyung; Camci-Unal, Gulden; Dokmeci, Mehmet R.

2014-01-01

Hydrogels are hydrophilic polymer-based materials with high water content and physical characteristics that resemble the native extracellular matrix. Because of their remarkable properties, hydrogel systems are used for a wide range of biomedical applications, such as three-dimensional (3D) matrices for tissue engineering, drug-delivery vehicles, composite biomaterials, and as injectable fillers in minimally invasive surgeries. In addition, the rational design of hydrogels with controlled physical and biological properties can be used to modulate cellular functionality and tissue morphogenesis. Here, the development of advanced hydrogels with tunable physiochemical properties is highlighted, with particular emphasis on elastomeric, light-sensitive, composite, and shape-memory hydrogels. Emerging technologies developed over the past decade to control hydrogel architecture are also discussed and a number of potential applications and challenges in the utilization of hydrogels in regenerative medicine are reviewed. It is anticipated that the continued development of sophisticated hydrogels will result in clinical applications that will improve patient care and quality of life. PMID:24741694

pH and Glucose Dual-Responsive Injectable Hydrogels with Insulin and Fibroblasts as Bioactive Dressings for Diabetic Wound Healing.

PubMed

Zhao, Lingling; Niu, Lijing; Liang, Hongze; Tan, Hui; Liu, Chaozong; Zhu, Feiyan

2017-11-01

pH and glucose dual-responsive injectable hydrogels were prepared through the cross-linking of Schiff's base and phenylboronate ester using phenylboronic-modified chitosan, poly(vinyl alcohol) and benzaldehyde-capped poly(ethylene glycol). Protein drugs and live cells could be incorporated into the hydrogels during the in situ cross-linking, displaying sustained and pH/glucose-triggered drug release from the hydrogels and cell viability and proliferation in the three-dimensional hydrogel matrix as well. Hence, the hydrogels with insulin and fibroblasts were considered as bioactive dressings for diabetic wound healing. A streptozotocin-induced diabetic rat model was used to evaluate the efficacy of hydrogel dressings in wound repair. The results revealed that the incorporation of insulin and L929 in the hydrogels could promote neovascularization and collagen deposition and enhance the wound-healing process of diabetic wounds. Thus, the drug- and cell-loaded hydrogels have promising potential in wound healing as a medicated system for various therapeutic proteins and live cells.

Gelam (Melaleuca spp.) Honey-Based Hydrogel as Burn Wound Dressing

PubMed Central

Mohd Zohdi, Rozaini; Abu Bakar Zakaria, Zuki; Yusof, Norimah; Mohamed Mustapha, Noordin; Abdullah, Muhammad Nazrul Hakim

2012-01-01

A novel cross-linked honey hydrogel dressing was developed by incorporating Malaysian honey into hydrogel dressing formulation, cross-linked and sterilized using electron beam irradiation (25 kGy). In this study, the physical properties of the prepared honey hydrogel and its wound healing efficacy on deep partial thickness burn wounds in rats were assessed. Skin samples were taken at 7, 14, 21, and 28 days after burn for histopathological and molecular evaluations. Application of honey hydrogel dressings significantly enhanced (P < 0.05) wound closure and accelerated the rate of re-epithelialization as compared to control hydrogel and OpSite film dressing. A significant decrease in inflammatory response was observed in honey hydrogel treated wounds as early as 7 days after burn (P < 0.05). Semiquantitative analysis using RT-PCR revealed that treatment with honey hydrogel significantly (P < 0.05) suppressed the expression of proinflammatory cytokines (IL-1α, IL-1β, and IL-6). The present study substantiates the potential efficacy of honey hydrogel dressings in accelerating burn wound healing. PMID:21941590

Novel levan and pNIPA temperature sensitive hydrogels for 5-ASA controlled release.

PubMed

Osman, Asila; Oner, Ebru Toksoy; Eroglu, Mehmet S

2017-06-01

Levan based cross-linker was successfully synthesized and used to prepare a series of more biocompatible and temperature responsive levan/N-isopropyl acrylamide (levan/pNIPA) hydrogels by redox polymerization at room temperature. Volume phase transition temperature (VPTT) of the hydrogels were precisely determined by derivative differential scanning calorimetry (DDSC). Incorporation of levan into the pNIPA hydrogel increased the VPTT from 32.8°C to 35.09°C, approaching to body temperature. Swelling behavior and 5-aminosalicylic acid (5-ASA) release of the hydrogels were found to vary significantly with temperature and composition. Moreover, a remarkable increase in thermal stability of levan within hydrogel with increase of pNIPA content was recorded. The biocompatibility of the hydrogels were tested against mouse fibroblast L929 cell line in phosphate buffer saline (PBS, pH 7.4). The hydrogels showed increasing biocompatibility with increasing levan ratio, indicating levan enhanced the hydrogel surface during swelling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and characterization of oil palm frond based cellulose hydrogel and its swelling properties

NASA Astrophysics Data System (ADS)

Selvakumaran, Nesha; Lazim, Mohd Azwani Shah bin Mat

2016-11-01

Malaysia is one of the largest producer of palm oil thus the quantity of biomass each year from this industry is very large. The oil palm frond from palm oil industry can be used as a source of cellulose which can be incorporated into hydrogel to be used as adsorbent. This research reported how to disperse 2 % cellulose in a `green-solution' prepared by using urea and sodium hydroxide. Polymerization is carried out between the monomers polyacrylamide and cellulose using microwave to form hydrogel. Hydrogel with 2 % cellulose have a swelling index of 1814 %. Meanwhile, zero hydrogel which is made with only polyacrylamide has swelling index of 15 %. Scanning electron microscope shows that cellulose hydrogel have a rough surface compared with zero hydrogel. This might attribute to the high swelling index for cellulose hydrogel compared with zero hydrogel. Meanwhile, FTIR shows that successful polymerization has occurred between polyacrylamide and cellulose with the characteristic band at 1657.99 cm-1 which is for N-H bond.

Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water

PubMed Central

Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X.; Zhao, Xuanhe

2017-01-01

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water. PMID:28145412

Effect of silane coupling agents on the chemical and physical properties of photocrosslinked poly(dimethylsiloxane) dimethacrylate/poly(ethylene glycol) diacrylate hydrogel

NASA Astrophysics Data System (ADS)

Lim, K. W.; Hamid, Z. A. A.

2017-07-01

Inorganic-organic hydrogels based on dimethacrylated polydimethylsiloxane (PDMSMA) and diacrylated poly(ethylene glycol) (PEGDA) macromers were prepared via photocrosslinking method. Silane coupling agent was incorporated into the hydrogel formulations to overcome the phase incompatibility. Pure PEGDA (0:100) hydrogels showed the highest value of ESR %, while pure PDMSMA (100:0) hydrogels showed no swelling as we expected. Inclusion of more hydrophobic domains resulted in a lower value of ESR %, i.e. in 75:25 hybrid hydrogels. Beside, we had noticed 50:50 and 75:25 hybrid hydrogels disintegrate during swelling period. However, their integrity was improved and sustained after the coupling agent was added. Similarly, the value of E* for the hybrid hydrogels showed an increment after the coupling agent was incorporated, and this is in a good agreement with the SEM micrograph which display an improved interfacial adhesion.

Preparation and characterization of poly(vinyl alcohol)/sodium alginate hydrogel with high toughness and electric conductivity.

PubMed

Jiang, Xiancai; Xiang, Nanping; Zhang, Hongxiang; Sun, Yujun; Lin, Zhen; Hou, Linxi

2018-04-15

Development of bio-based hydrogels with good mechanical properties and high electrical conductivity is of great importance for their excellent biocompatibility and biodegradability. Novel electrically conducive and tough poly(vinyl alcohol)/sodium alginate (PVA/SA) composite hydrogel was obtained by a simple method in this paper. PVA and SA were firstly dissolved in distilled water to form the composite solution and the pure PVA/SA hydrogel was obtained through the freezing/thawing process. The pure PVA/SA hydrogels were subsequently immersed into the saturated NaCl aqueous solution to increase the gel strength and conductivity. The effect of the immersing time on the thermal and mechanical properties of PVA/SA hydrogel was studied. The swelling properties and the antiseptic properties of the obtained PVA/SA hydrogel were also studied. This paper provided a novel way for the preparation of tough hydrogel electrolyte. Copyright © 2018. Published by Elsevier Ltd.

Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water.

PubMed

Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X; Zhao, Xuanhe

2017-02-01

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water.

Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water

NASA Astrophysics Data System (ADS)

Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X.; Zhao, Xuanhe

2017-02-01

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water.

CMOS image sensor-based implantable glucose sensor using glucose-responsive fluorescent hydrogel.

PubMed

Tokuda, Takashi; Takahashi, Masayuki; Uejima, Kazuhiro; Masuda, Keita; Kawamura, Toshikazu; Ohta, Yasumi; Motoyama, Mayumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Okitsu, Teru; Takeuchi, Shoji; Ohta, Jun

2014-11-01

A CMOS image sensor-based implantable glucose sensor based on an optical-sensing scheme is proposed and experimentally verified. A glucose-responsive fluorescent hydrogel is used as the mediator in the measurement scheme. The wired implantable glucose sensor was realized by integrating a CMOS image sensor, hydrogel, UV light emitting diodes, and an optical filter on a flexible polyimide substrate. Feasibility of the glucose sensor was verified by both in vitro and in vivo experiments.

Imaging cell picker: A morphology-based automated cell separation system on a photodegradable hydrogel culture platform.

PubMed

Shibuta, Mayu; Tamura, Masato; Kanie, Kei; Yanagisawa, Masumi; Matsui, Hirofumi; Satoh, Taku; Takagi, Toshiyuki; Kanamori, Toshiyuki; Sugiura, Shinji; Kato, Ryuji

2018-06-09

Cellular morphology on and in a scaffold composed of extracellular matrix generally represents the cellular phenotype. Therefore, morphology-based cell separation should be interesting method that is applicable to cell separation without staining surface markers in contrast to conventional cell separation methods (e.g., fluorescence activated cell sorting and magnetic activated cell sorting). In our previous study, we have proposed a cloning technology using a photodegradable gelatin hydrogel to separate the individual cells on and in hydrogels. To further expand the applicability of this photodegradable hydrogel culture platform, we here report an image-based cell separation system imaging cell picker for the morphology-based cell separation on a photodegradable hydrogel. We have developed the platform which enables the automated workflow of image acquisition, image processing and morphology analysis, and collection of a target cells. We have shown the performance of the morphology-based cell separation through the optimization of the critical parameters that determine the system's performance, such as (i) culture conditions, (ii) imaging conditions, and (iii) the image analysis scheme, to actually clone the cells of interest. Furthermore, we demonstrated the morphology-based cloning performance of cancer cells in the mixture of cells by automated hydrogel degradation by light irradiation and pipetting. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Hydrogel ionotronics

NASA Astrophysics Data System (ADS)

Yang, Canhui; Suo, Zhigang

2018-06-01

An ionotronic device functions by a hybrid circuit of mobile ions and mobile electrons. Hydrogels are stretchable, transparent, ionic conductors that can transmit electrical signals of high frequency over long distance, enabling ionotronic devices such as artificial muscles, skins and axons. Moreover, ionotronic luminescent devices, ionotronic liquid crystal devices, touchpads, triboelectric generators, artificial eels and gel-elastomer-oil devices can be designed based on hydrogels. In this Review, we discuss first-generation hydrogel ionotronic devices and the challenges associated with the mechanical properties and the chemistry of the materials. We examine how strong and stretchable adhesion between hydrophilic and hydrophobic polymer networks can be achieved, how water can be retained in hydrogels and how to design hydrogels that resist fatigue under cyclic loads. Finally, we highlight applications of hydrogel ionotronic devices and discuss the future of the field.

Dextran/Albumin hydrogel sealant for Dacron(R) vascular prosthesis.

PubMed

Lisman, Anna; Butruk, Beata; Wasiak, Iga; Ciach, Tomasz

2014-05-01

In this paper, the authors describe a novel type of hydrogel coating prepared from the copolymer of human serum albumin and oxidized dextran. The material was designed as a hydrogel sealant for polyester (Dacron®)-based vascular grafts. Dextran was chosen as a coating material due to its anti-thrombogenic properties. Prepared hydrogels were compared with similar, already known biomaterial made from gelatine with the same cross-linking agent. Obtained hydrogels, prepared from various ratios of oxidized dextran/albumin or oxidized dextran/gelatine, showed different cross-linking densities, which caused differences in swelling, degradation rate and mechanical properties. Permeability tests confirmed the complete tightness of the hydrogel-modified prosthesis. Results showed that application of the hydrogel coating provided leakage-free prosthesis and eliminated the need of pre-clotting.

A precision structured smart hydrogel for sensing applications

NASA Astrophysics Data System (ADS)

Menges, J.; Kleinschmidt, P.; Bart, H.-J.; Oesterschulze, E.

2017-10-01

We report on a macroinitiator based smart hydrogel film applied on a microcantilever for sensing applications. The studied hydrogel features a comparatively wide dynamic range for changes in the electrolyte's ionic strength. Furthermore, it offers a simple spin coating process for thin film deposition as well as the capability to obtain high aspect ratio microstructures by reactive ion etching. This makes the hydrogel compatible to microelectromechanical system integration. As a proof of concept, we study the response of hydrogel functionalized cantilevers in aqueous sodium chloride solutions of varying ionic strength. In contrast to the majority of hydrogel materials reported in the literature, we found that our hydrogel still responds in high ionic strength environments. This may be of future interest for sensing e.g., in sea water or physiological environments like urine.

A highly printable and biocompatible hydrogel composite for direct printing of soft and perfusable vasculature-like structures.

PubMed

Suntornnond, Ratima; Tan, Edgar Yong Sheng; An, Jia; Chua, Chee Kai

2017-12-04

Vascularization is one major obstacle in bioprinting and tissue engineering. In order to create thick tissues or organs that can function like original body parts, the presence of a perfusable vascular system is essential. However, it is challenging to bioprint a hydrogel-based three-dimensional vasculature-like structure in a single step. In this paper, we report a new hydrogel-based composite that offers impressive printability, shape integrity, and biocompatibility for 3D bioprinting of a perfusable complex vasculature-like structure. The hydrogel composite can be used on a non-liquid platform and is printable at human body temperature. Moreover, the hydrogel composite supports both cell proliferation and cell differentiation. Our results represent a potentially new vascularization strategy for 3D bioprinting and tissue engineering.

Chitosan/chondroitin sulfate hydrogels prepared in [Hmim][HSO4] ionic liquid.

PubMed

Nunes, Cátia S; Rufato, Kessily B; Souza, Paulo R; de Almeida, Elizângela A M S; da Silva, Michael J V; Scariot, Débora B; Nakamura, Celso V; Rosa, Fernanda A; Martins, Alessandro F; Muniz, Edvani C

2017-08-15

[Hmim][HSO 4 ] ionic liquid (IL) and bio-renewable sources as chitosan (CHT) and chondroitin sulfate (CS) were used to yield hydrogel-based materials (CHT/CS). The use of IL to solubilize both polysaccharides was considered an innovative way based on "green chemistry" principle, aiming the production of CHT/CS blended systems. CHT/CS hydrogels were carried out in homogeneous medium from short dissolution times. The hydrogels were characterized and achieved with excellent stabilities (in the 1.2-10pH range), larger swelling capacities, as well as devoid of cytotoxicity towards the normal VERO and diseased HT29 cells. The CHT/CS hydrogels carried out in [Hmim][HSO 4 ] could be applied in many technological purposes, like medical, pharmaceutical, and environmental fields. Copyright © 2017 Elsevier Ltd. All rights reserved.

Injectable hydrogels for delivering biotherapeutic molecules.

PubMed

Mathew, Ansuja Pulickal; Uthaman, Saji; Cho, Ki-Hyun; Cho, Chong-Su; Park, In-Kyu

2018-04-15

To date, numerous delivery systems based on either organic or inorganic material have been developed to achieve efficient and sustained delivery of therapeutics. Hydrogels, which are three dimensional networks of crosslinked hydrophilic polymers, have a significant role in solving the clinical and pharmacological limitations of present systems because of their biocompatibility, ease of preparation and unique physical properties such as a tunable porous nature and affinity for biological fluids. Development of an in situ forming injectable hydrogel system has allowed excellent spatial and temporal control, unlike systemically administered therapeutics. Injectable hydrogel systems can offset difficulties with conventional hydrogel-based drug delivery systems in the clinic by forming a drug/gene delivery or cell-growing depot in the body with a single injection, thereby enabling patient compliance and comfort. Carbohydrate polymers are widely used for the synthesis of injectable in situ-forming hydrogels because of ready availability, presence of modifiable functional groups, biocompatibility and other physiochemical properties. In this review, we discuss different aspects of injectable hydrogels, such as bulk hydrogels/macrogels, microgels, and nanogels derived from natural polymers, and their importance in the delivery of therapeutics such as genes, drugs, cells or other biomolecules and how these revolutionary systems can complement existing therapeutic delivery systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Rheological performance of bacterial cellulose based nonmineralized and mineralized hydrogel scaffolds

NASA Astrophysics Data System (ADS)

Basu, Probal; Saha, Nabanita; Bandyopadhyay, Smarak; Saha, Petr

2017-05-01

Bacterial cellulose (BC) based hydrogels (BC-PVP and BC-CMC) are modified with β-tri-calcium phosphate (β-TCP) and hydroxyapatite (HA) to improve the structural and functional properties of the existing hydrogel scaffolds. The modified hydrogels are then biomineralized with CaCO3 following liquid diffusion technique, where salt solutions of Na2CO3 (5.25 g/100 mL) and CaCl2 (7.35 g/100 mL) were involved. The BC-PVP and BC-CMC are being compared with the non-mineralized (BC-PVP-β-TCP/HA and BC-CMC-β-TCP/HA) and biomineralized (BC-PVP-β-TCP/HA-CaCO3 and BC-CMC-β-TCP/HA-CaCO3) hydrogels on the basis of their structural and rheological properties. The Fourier Transform Infrared (FTIR) spectral analysis demonstrated the presence of BC, CMC, PVP, β-TCP, HA in the non-mineralized and BC, CMC, PVP, β-TCP, HA and CaCO3 in the biomineralized samples. Interestingly, the morphological property of non-mineralized and biomineralized, hydrogels are different than that of BC-PVP and BC-CMC based novel biomaterials. The Scanning Electron Microscopic (SEM) images of the before mentioned samples reveal the denser structures than BC-PVP and BC-CMC, which exhibits the changes in their pore sizes. Concerning rheological analysis point of view, all the non-mineralized and biomineralized hydrogel scaffolds have shown significant elastic property. Additionally, the complex viscosity (η*) values have also found in decreasing order with the increase of angular frequency (ω) 0.1 rad.sec-1 to 100 rad.sec-1. All these BC based hydrogel scaffolds are elastic in nature, can be recommended for their application as an implant for bone tissue engineering.

Superelastic, superabsorbent and 3D nanofiber-assembled scaffold for tissue engineering.

PubMed

Chen, Weiming; Ma, Jun; Zhu, Lei; Morsi, Yosry; -Ei-Hamshary, Hany; Al-Deyab, Salem S; Mo, Xiumei

2016-06-01

Fabrication of 3D scaffold to mimic the nanofibrous structure of the nature extracellular matrix (ECM) with appropriate mechanical properties and excellent biocompatibility, remain an important technical challenge in tissue engineering. The present study reports the strategy to fabricate a 3D nanofibrous scaffold with similar structure to collagen in ECM by combining electrospinning and freeze-drying technique. With the technique reported here, a nanofibrous structure scaffold with hydrophilic and superabsorbent properties can be readily prepared by Gelatin and Polylactic acid (PLA). In wet state the scaffold also shows a super-elastic property, which could bear a compressive strain as high as 80% and recovers its original shape afterwards. Moreover, after 6 days of culture, L-929 cells grow, proliferate and infiltrated into the scaffold. The results suggest that this 3D nanofibrous scaffold would be promising for varied field of tissue engineering application. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and properties of a coated slow-release and water-retention biuret phosphoramide fertilizer with superabsorbent.

PubMed

Jin, Shuping; Yue, Guoren; Feng, Lei; Han, Yuqi; Yu, Xinghai; Zhang, Zenghu

2011-01-12

In this investigation, a novel water-insoluble slow-release fertilizer, biuret polyphosphoramide (BPAM), was formulated and synthesized from urea, phosphoric acid (H(3)PO(4)), and ferric oxide (Fe(2)O(3)). The structure of BPAM was characterized by Fourier transform infrared (FTIR) spectroscopy. Subsequently, a coated slow-release BPAM fertilizer with superabsorbent was prepared by ionic cross-linked carboxymethylchitosan (the core), acrylic acid, acrylamide, and active carbon (the coating). The variable influences on the water absorbency were investigated and optimized. Component analysis results showed that the coated slow-release BPAM contained 5.66% nitrogen and 11.7% phosphorus. The property of water retention, the behavior of slow release of phosphorus, and the capacity of adsorption of cations were evaluated, and the results revealed that the product not only had good slow-release property and excellent water retention capacity but also higher adsorption capacities of cations in saline soil.

Synthesis and characterization of superabsorbent polymer prepared by radiation-induced graft copolymerization of acrylamide onto carboxymethyl cellulose for controlled release of agrochemicals

NASA Astrophysics Data System (ADS)

Hemvichian, Kasinee; Chanthawong, Auraruk; Suwanmala, Phiriyatorn

2014-10-01

Superabsorbent polymer (SAP) was synthesized by radiation-induced grafting of acrylamide (AM) onto carboxymethyl cellulose (CMC) in the presence of a crosslinking agent, N,N‧-methylenebisacrylamide (MBA). The effects of various parameters, such as dose, the amount of CMC, AM, MBA and ionic strength on the swelling ratio were investigated. In order to evaluate its controlled release potential, SAP was loaded with potassium nitrate (KNO3) as an agrochemical model and its potential for controlled release of KNO3 was studied. The amount of released KNO3 was analyzed by an inductively coupled plasma mass spectrometry (ICP-MS). The results from controlled release experiment agreed very well with the results from swelling experiment. The synthesized SAP was characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The obtained SAP exhibited a swelling ratio of 190 g/g of dry gel.

Superabsorbent polymer-containing wound dressings have a beneficial effect on wound healing by reducing PMN elastase concentration and inhibiting microbial growth.

PubMed

Wiegand, C; Abel, M; Ruth, P; Hipler, U C

2011-11-01

A comprehensive in vitro approach was used to assess the effects of superabsorbent polymer (SAP) containing wound dressings in treatment of non-healing wounds. A slight negative effect on HaCaT cells was noted in vitro which is most likely due to the Ca(2+) deprivation of the medium by binding to the SAP. It could be shown that SAP wound dressings are able to bind considerable amounts of elastase reducing enzyme activity significantly. Furthermore, SAP's inhibit the formation of free radicals. The SAP-containing wound dressings tested also exhibited a significant to strong antimicrobial activity effectively impeding the growth of gram-negative and gram-positive bacteria as well as yeasts. In conclusion, in vitro data confirm the positive effect of SAP wound dressings observed in vivo and suggest that they should be specifically useful for wound cleansing.

Mechanical testing of hydrogels in cartilage tissue engineering: beyond the compressive modulus.

PubMed

Xiao, Yinghua; Friis, Elizabeth A; Gehrke, Stevin H; Detamore, Michael S

2013-10-01

Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context.

Injectable dopamine-modified poly(α,β-aspartic acid) nanocomposite hydrogel as bioadhesive drug delivery system.

PubMed

Gong, Chu; Lu, Caicai; Li, Bingqiang; Shan, Meng; Wu, Guolin

2017-04-01

Hydrogel systems based on cross-linked polymeric materials with adhesive properties in wet environments have been considered as promising candidates for tissue adhesives. The 3,4-dihydroxyphenylalanine (DOPA) is believed to be responsible for the water-resistant adhesive characteristics of mussel adhesive proteins. Under the inspiration of DOPA containing adhesive proteins, a dopamine-modified poly(α,β-aspartic acid) derivative (PDAEA) was successfully synthesized by successive ring-opening reactions of polysuccinimide (PSI) with dopamine and ethanolamine, and an injectable bioadhesive hydrogel was prepared via simply mixing PDAEA and FeCl 3 solutions. The formation mechanism of the hydrogel was investigated by ultraviolet-visible (UV-vis) spectroscopic, Fourier transformation infrared (FT-IR) spectroscopic, visual colorimetric measurements and EDTA immersion methods. The study demonstrated that the PDAEA-Fe 3+ hydrogel is a dual cross-linking system composed of covalent and coordination crosslinks. The PDAEA-Fe 3+ hydrogel is suitable to serve as a bioadhesive agent according to the rheological behaviors and the observed significant shear adhesive strength. The slow and sustained release of the model drug curcumin from the hydrogel in vitro demonstrated the hydrogel could also be potentially used for drug delivery. Moreover, the cytotoxicity tests in vitro suggested the prepared polymer and hydrogel possessed excellent cytocompatibility. All the results indicated that the dopamine modified poly(α,β-aspartic acid) derivative based hydrogel was a promising candidate for bioadhesive drug delivery system. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1000-1008, 2017. © 2017 Wiley Periodicals, Inc.

N-isopropylacrylamide-based fine-dispersed thermosensitive ferrogels obtained via in-situ technique.

PubMed

Korotych, O; Samchenko, Yu; Boldeskul, I; Ulberg, Z; Zholobak, N; Sukhodub, L

2013-03-01

Thermosensitive hydrogels with magnetic properties (ferrogels) are very promising for medical application, first of all, for the design of targeted delivery systems with controlled release of drugs and for magnetic hyperthermia and chemotherapy treatment of cancer. These magnetic hydrogels could be obtained using diverse techniques: ex- and in-situ syntheses. The present work is devoted to the study of magnetite (Fe(3)O(4)) formation inside the nanoreactors of (co)polymeric hydrogels. Polymeric templates (hydrogel films and fine-dispersed hydrogels) used for obtaining ferrogels were based on acrylic monomers: thermosensitive N-isopropylacrylamide, and hydrophilic acrylamide. Covalent cross-linking was accomplished using bifunctional monomer N,N'-methylenebisacrylamide. Influence of hydrophilic-lipophilic balance of polymeric templates and concentration of iron cations on the magnetite formation were investigated along with the development of ferrogel preparation technique. Cytotoxicity, physical and chemical properties of obtained magnetic hydrogels have been studied in this work. Copyright © 2012 Elsevier B.V. All rights reserved.

Novel Injectable Pentablock Copolymer Based Thermoresponsive Hydrogels for Sustained Release Vaccines.

PubMed

Bobbala, Sharan; Tamboli, Viral; McDowell, Arlene; Mitra, Ashim K; Hook, Sarah

2016-01-01

The need for multiple vaccinations to enhance the immunogenicity of subunit vaccines may be reduced by delivering the vaccine over an extended period of time. Here, we report two novel injectable pentablock copolymer based thermoresponsive hydrogels made of polyethyleneglycol-polycaprolactone-polylactide-polycaprolactone-polyethyleneglycol (PEG-PCL-PLA-PCL-PEG) with varying ratios of polycaprolactone (PCL) and polylactide (PLA), as single shot sustained release vaccines. Pentablock copolymer hydrogels were loaded with vaccine-encapsulated poly lactic-co-glycolic acid nanoparticles (PLGA-NP) or with the soluble vaccine components. Incorporation of PLGA-NP into the thermoresponsive hydrogels increased the complex viscosity of the gels, lowered the gelation temperature, and minimized the burst release of antigen and adjuvants. The two pentablock hydrogels stimulated both cellular and humoral responses. The addition of PLGA-NP to the hydrogels sustained immune responses for up to 49 days. The polymer with a higher ratio of PCL to PLA formed a more rigid gel, induced stronger immune responses, and stimulated effective anti-tumor responses in a prophylactic melanoma tumor model.

Viscoelastic behavior of mineralized (CaCO3) chitin based PVP-CMC hydrogel scaffolds

NASA Astrophysics Data System (ADS)

Čadež, Vida; Saha, Nabanita; Sikirić, Maja Dutour; Saha, Petr

2017-05-01

Enhancement of the mechanical as well as functional properties of the perspective mineralized PVP-CMC-CaCO3 hydrogel scaffold applicable for bone tissue engineering is quite essential. Therefore, the incorporation feasibility of chitin, a bioactive, antibacterial and biodegradable material, was examined in order to test its ability to enchance mechanical properties of the PVP-CMC-CaCO3 hydrogel scaffold. Chitin based PVP-CMC hydrogels were prepared and characterized both as non-mineralized and mineralized (CaCO3) form of hydrogel scaffolds. Both α-chitin (commercially bought) and β-chitin (isolated from the cuttlebone) were individually tested. It was observed that at 1% strain all hydrogel scaffolds have linear trend, with highly pronounced elastic properties in comparison to viscous ones. The complex viscosity has directly proportional behavior with negative slope against angular frequency within the range of ω = 0.1 - 100 rad.s-1. Incorporation of β-chitin increased storage modulus of all mineralized samples, making it interesting for further research.

CMOS image sensor-based implantable glucose sensor using glucose-responsive fluorescent hydrogel

PubMed Central

Tokuda, Takashi; Takahashi, Masayuki; Uejima, Kazuhiro; Masuda, Keita; Kawamura, Toshikazu; Ohta, Yasumi; Motoyama, Mayumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Okitsu, Teru; Takeuchi, Shoji; Ohta, Jun

2014-01-01

A CMOS image sensor-based implantable glucose sensor based on an optical-sensing scheme is proposed and experimentally verified. A glucose-responsive fluorescent hydrogel is used as the mediator in the measurement scheme. The wired implantable glucose sensor was realized by integrating a CMOS image sensor, hydrogel, UV light emitting diodes, and an optical filter on a flexible polyimide substrate. Feasibility of the glucose sensor was verified by both in vitro and in vivo experiments. PMID:25426316

Modulating release of ranibizumab and aflibercept from thiolated chitosan-based hydrogels for potential treatment of ocular neovascularization.

PubMed

Moreno, Miguel; Pow, Poh Yih; Tabitha, Tan Su Teng; Nirmal, Sonali; Larsson, Andreas; Radhakrishnan, Krishna; Nirmal, Jayabalan; Quah, Soo Tng; Geifman Shochat, Susana; Agrawal, Rupesh; Venkatraman, Subbu

2017-08-01

This paper describes the synthesis of thiolated chitosan-based hydrogels with varying degrees of crosslinking that has been utilized to modulate release kinetics of two clinically relevant FDA-approved anti-VEGF protein drugs, ranibizumab and aflibercept. These hydrogels have been fabricated into disc shaped structures for potential use as patches on ocular surface. Protein conformational changes and aggregation after loading and release was evaluated by circular dichroism (CD), steady-state tryptophan fluorescence spectroscopy, electrophoresis and size-exclusion chromatography (SEC). Finally, the capacity of both released proteins to bind to VEGF was tested by ELISA and surface plasmon resonance (SPR) technology. The study demonstrates the versatility of thiolated chitosan-based hydrogels for delivering proteins. The effect of various parameters of the hydrogel on protein release kinetics and mechanism of protein release was studied using the Korsmeyer-Peppas release model. Furthermore, we have studied the stability of released proteins in detail while comparing it with non-entrapped proteins under physiological conditions to understand the effect of formulation conditions on protein stability. The disc-shaped thiolated chitosan-based hydrogels provide a potentially useful platform to deliver ranibizumab and aflibercept for the treatments of ocular diseases such as wet AMD, DME and corneal neovascularization.

Study of the effect of mixing approach on cross-linking efficiency of hyaluronic acid-based hydrogel cross-linked with 1,4-butanediol diglycidyl ether.

PubMed

Al-Sibani, Mohammed; Al-Harrasi, Ahmed; Neubert, Reinhard H H

2016-08-25

Regardless of various strategies reported for cross-linking hyaluronic acid (HA) with 1,4-butanediol diglycidyl ether (BDDE), seeking new strategies that enhance cross-linking efficiency with a low level of cross-linker is essential. In this work, we studied the influence of mixing approach on two cross-linked BDDE-HA hydrogels prepared by two different mixing approaches; the large-batch mixing approach in which the hydrogel quantities were all mixed as a single lump in one container (hydrogel 1), and the small-batches mixing approach in which the hydrogel quantities were divided into smaller batches, mixed separately at various HA/BDDE ratios then combined in one reaction mixture (hydrogel 2). The result showed that the cross-linking reaction was mixing process-dependent. Degradation tests proved that, in relation to hydrogel 1, hydrogel 2 was more stable, and exhibited a higher resistance towards hyaluronidase activity. The swelling ratio of hydrogel 1 was significantly higher than that of hydrogel 2 in distilled water; however, in phosphate buffer saline, both hydrogels showed no significant difference. SEM images demonstrated that hydrogel 2 composite showed a denser network structure and smaller pore-size than hydrogel 1. In comparison to native HA, the occurrence of chemical modification in the cross-linked hydrogels was confirmed by FTIR and NMR distinctive peaks. These peaks also provided evidence that hydrogel 2 exhibited a higher degree of modification than hydrogel 1. In conclusion, the small-batches mixing approach proved to be more effective than large-batch mixing in promoting HA-HA entanglement and increasing the probability of BDDE molecules for binding with HA chains. Copyright © 2016 Elsevier B.V. All rights reserved.

Biomimetic hydrogel loaded with silk and l-proline for tissue engineering and wound healing applications.

PubMed

Thangavel, Ponrasu; Ramachandran, Balaji; Kannan, Ramya; Muthuvijayan, Vignesh

2017-08-01

The aim of this article was to develop silk protein (SF) and l-proline (LP) loaded chitosan-(CS) based hydrogels via physical cross linking for tissue engineering and wound healing applications. Silk fibroin, a biodegradable and biocompatible protein, and l-proline, an important imino acid that is required for collagen synthesis, were added to chitosan to improve the wound healing properties of the hydrogel. Characterization of these hydrogels revealed that CS/SF/LP hydrogels were blended properly and LP incorporated hydrogels showed excellent thermal stability and good surface morphology. Swelling study showed the water holding efficiency of the hydrogels to provide enough moisture at the wound surface. In vitro biodegradation results demonstrated that the hydrogels had good degradation rate in PBS with lysozyme. LP loaded hydrogels showed approximately a twofold increase in antioxidant activity. In vitro cytocompatibility studies using NIH 3T3 L1 cells showed increased cell viability (p < 0.01), migration, proliferation and wound healing activity (p < 0.001) in LP loaded hydrogels compared to CS and CS/SF hydrogels. Cell adhesion on SF and LP hydrogels were observed using SEM and compared to CS hydrogel. LP incorporation showed 74-78% of wound closure compared to 35% for CS/SF and 3% for CS hydrogels at 48 h. These results suggest that incorporation of LP can significantly accelerate wound healing process compared to pure CS and SF-loaded CS hydrogels. Hence, CS/LP hydrogels could be a potential wound dressing material for the enhanced wound tissue regeneration and repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1401-1408, 2017. © 2016 Wiley Periodicals, Inc.

Supramolecular Hydrogels Based on DNA Self-Assembly.

PubMed

Shao, Yu; Jia, Haoyang; Cao, Tianyang; Liu, Dongsheng

2017-04-18

Extracellular matrix (ECM) provides essential supports three dimensionally to the cells in living organs, including mechanical support and signal, nutrition, oxygen, and waste transportation. Thus, using hydrogels to mimic its function has attracted much attention in recent years, especially in tissue engineering, cell biology, and drug screening. However, a hydrogel system that can merit all parameters of the natural ECM is still a challenge. In the past decade, deoxyribonucleic acid (DNA) has arisen as an outstanding building material for the hydrogels, as it has unique properties compared to most synthetic or natural polymers, such as sequence designability, precise recognition, structural rigidity, and minimal toxicity. By simple attachment to polymers as a side chain, DNA has been widely used as cross-links in hydrogel preparation. The formed secondary structures could confer on the hydrogel designable responsiveness, such as response to temperature, pH, metal ions, proteins, DNA, RNA, and small signal molecules like ATP. Moreover, single or multiple DNA restriction enzyme sites could be incorporated into the hydrogels by sequence design and greatly expand the latitude of their responses. Compared with most supramolecular hydrogels, these DNA cross-linked hydrogels could be relatively strong and easily adjustable via sequence variation, but it is noteworthy that these hydrogels still have excellent thixotropic properties and could be easily injected through a needle. In addition, the quick formation of duplex has also enabled the multilayer three-dimensional injection printing of living cells with the hydrogel as matrix. When the matrix is built purely by DNA assembly structures, the hydrogel inherits all the previously described characteristics; however, the long persistence length of DNA structures excluded the small size meshes of the network and made the hydrogel permeable to nutrition for cell proliferation. This unique property greatly expands the cell viability in the three-dimensional matrix to several weeks and also provides an easy way to prepare interpenetrating double network materials. In this Account, we outline the stream of hydrogels based on DNA self-assembly and discuss the mechanism that brings outstanding properties to the materials. Unlike most reported hydrogel systems, the all-in-one character of the DNA hydrogel avoids the "cask effect" in the properties. We believe the hydrogel will greatly benefit cell behavior studies especially in the following aspects: (1) stem cell differentiation can be studied with solely tunable mechanical strength of the matrix; (2) the dynamic nature of the network can allow cell migration through the hydrogel, which will help to build a more realistic model to observe the migration of cancer cells in vivo; (3) combination with rapidly developing three-dimension printing technology, the hydrogel will boost the construction of three-dimensional tissues and artificial organs.

Hydrogel Walkers with Electro-Driven Motility for Cargo Transport.

PubMed

Yang, Chao; Wang, Wei; Yao, Chen; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

2015-08-28

In this study, soft hydrogel walkers with electro-driven motility for cargo transport have been developed via a facile mould-assisted strategy. The hydrogel walkers consisting of polyanionic poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylamide) exhibit an arc looper-like shape with two "legs" for walking. The hydrogel walkers can reversibly bend and stretch via repeated "on/off" electro-triggers in electrolyte solution. Based on such bending/stretching behaviors, the hydrogel walkers can move their two "legs" to achieve one-directional walking motion on a rough surface via repeated "on/off" electro-triggering cycles. Moreover, the hydrogel walkers loaded with very heavy cargo also exhibit excellent walking motion for cargo transport. Such hydrogel systems create new opportunities for developing electro-controlled soft systems with simple design/fabrication strategies in the soft robotic field for remote manipulation and transportation.

DNA Hydrogel with Tunable pH-Responsive Properties Produced by Rolling Circle Amplification.

PubMed

Xu, Wanlin; Huang, Yishun; Zhao, Haoran; Li, Pan; Liu, Guoyuan; Li, Jing; Zhu, Chengshen; Tian, Leilei

2017-12-22

Recently, smart DNA hydrogels, which are generally formed by the self-assembly of oligonucleotides or through the cross-linking of oligonucleotide-polymer hybrids, have attracted tremendous attention. However, the difficulties of fabricating DNA hydrogels limit their practical applications. We report herein a novel method for producing pH-responsive hydrogels by rolling circle amplification (RCA). In this method, pH-sensitive cross-linking sites were introduced into the polymeric DNA chains during DNA synthesis. As the DNA sequence can be precisely defined by its template, the properties of such hydrogels can be finely tuned in a very facile way through template design. We have investigated the process of hydrogel formation and pH-responsiveness to provide rationales for functional hydrogel design based on the RCA reaction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bimodal self-assembly of an amphiphilic gelator into a hydrogel-nanocatalyst and an organogel with different morphologies and photophysical properties.

PubMed

Sutar, Papri; Maji, Tapas Kumar

2016-11-18

We design a flexible, amphiphilic LMWG consisting of donor and acceptor π-chromophores which self-assembles into a hydrogel and an organogel with different nano-morphologies. Different mechanisms of self-assembly evolve charge transfer (CT) emission in the hydrogel and LMWG-based emission in the organogel. Moreover, the hydrogel-nanostructure with surface exposed amide groups is explored for catalyzing Knoevenagel condensation reaction.

Hydrogel based cartilaginous tissue regeneration: recent insights and technologies.

PubMed

Chuah, Yon Jin; Peck, Yvonne; Lau, Jia En Josias; Hee, Hwan Tak; Wang, Dong-An

2017-03-28

Hydrogels have been extensively employed as an attractive biomaterial to address numerous existing challenges in the fields of regenerative medicine and research because of their unique properties such as the capability to encapsulate cells, high water content, ease of modification, low toxicity, injectability, in situ spatial fit and biocompatibility. These inherent properties have created many opportunities for hydrogels as a scaffold or a cell/drug carrier in tissue regeneration, especially in the field of cartilaginous tissue such as articular cartilage and intervertebral discs. A concise overview of the anatomy/physiology of these cartilaginous tissues and their pathophysiology, epidemiology and existing clinical treatments will be briefly described. This review article will discuss the current state-of-the-art of various polymers and developing strategies that are explored in establishing different technologies for cartilaginous tissue regeneration. In particular, an innovative approach to generate scaffold-free cartilaginous tissue via a transient hydrogel scaffolding system for disease modeling to pre-clinical trials will be examined. Following that, the article reviews numerous hydrogel-based medical implants used in clinical treatment of osteoarthritis and degenerated discs. Last but not least, the challenges and future directions of hydrogel based medical implants in the regeneration of cartilaginous tissue are also discussed.

SAM-based cell transfer to photopatterned hydrogels for microengineering vascular-like structures.

PubMed

Sadr, Nasser; Zhu, Mojun; Osaki, Tatsuya; Kakegawa, Takahiro; Yang, Yunzhi; Moretti, Matteo; Fukuda, Junji; Khademhosseini, Ali

2011-10-01

A major challenge in tissue engineering is to reproduce the native 3D microvascular architecture fundamental for in vivo functions. Current approaches still lack a network of perfusable vessels with native 3D structural organization. Here we present a new method combining self-assembled monolayer (SAM)-based cell transfer and gelatin methacrylate hydrogel photopatterning techniques for microengineering vascular structures. Human umbilical vein cell (HUVEC) transfer from oligopeptide SAM-coated surfaces to the hydrogel revealed two SAM desorption mechanisms: photoinduced and electrochemically triggered. The former, occurs concomitantly to hydrogel photocrosslinking, and resulted in efficient (>97%) monolayer transfer. The latter, prompted by additional potential application, preserved cell morphology and maintained high transfer efficiency of VE-cadherin positive monolayers over longer culture periods. This approach was also applied to transfer HUVECs to 3D geometrically defined vascular-like structures in hydrogels, which were then maintained in perfusion culture for 15 days. As a step toward more complex constructs, a cell-laden hydrogel layer was photopatterned around the endothelialized channel to mimic the vascular smooth muscle structure of distal arterioles. This study shows that the coupling of the SAM-based cell transfer and hydrogel photocrosslinking could potentially open up new avenues in engineering more complex, vascularized tissue constructs for regenerative medicine and tissue engineering applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

A POSS based hydrogel with mechanical robustness, cohesiveness and a rapid self-healing ability by electrostatic interaction.

PubMed

Pu, Wanfen; Jiang, Feng; Chen, Pei; Wei, Bing

2017-08-30

A molecularly dispersed nano-material called POSS-NH 2 -AA was synthesized to construct a hybrid hydrogel with a rapid self-healing ability (stress 8 kPa) and excellent mechanical performance (a strain of 4683% and a stress of 37.8 kPa). The hydrogel also exhibits good cohesiveness to materials, such as plastics, glass and iron. The backbone of the POSS makes the hydrogel much stronger than the hydrogel without POSS, which accounts for the improvement in its properties. This process is facile and useful to construct mechanically strong and self-healable materials.

Development of a P((MAA-co-NVP)-g-EG) Hydrogel Platform for Oral Protein Delivery: Effects of Hydrogel Composition on Environmental Response and Protein Partitioning.

PubMed

Steichen, Stephanie; O'Connor, Colleen; Peppas, Nicholas A

2017-01-01

Hydrogels based upon terpolymers of methacrylic acid, N-vinyl pyrrolidone, and poly(ethylene glycol) are developed and characterized for their ability to respond to changes in environmental pH and to partition protein therapeutics of varying molecular weights and isoelectric points. P((MAA-co-NVP)-g-EG) hydrogels are synthesized with PEG-based cross-linking agents of varying length and incorporation densities. The composition is confirmed using FT-IR spectroscopy and shows peak shifts indicating hydrogen bonding. Scanning electron microscopy reveals microparticles with an irregular, planar morphology. The pH-responsive behavior of the hydrogels is confirmed under equilibrium and dynamic conditions, with the hydrogel collapsed at acidic pH and swollen at neutral pH. The ability of the hydrogels to partition model protein therapeutics at varying pH and ionic strength is evaluated using three model proteins: insulin, porcine growth hormone, and ovalbumin. Finally, the microparticles are evaluated for adverse interactions with two model intestinal cell lines and show minimal cytotoxicity at concentrations below 5 mg mL -1 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of xanthan gum on lipid digestion and bioaccessibility of β-carotene-loaded rice starch-based filled hydrogels.

PubMed

Park, Shinjae; Mun, Saehun; Kim, Yong-Ro

2018-03-01

The aim of this study was to examine the effects of xanthan gum on the lipid digestibility, rheological properties, and β-carotene bioaccessibility of rice starch-based filled hydrogels. β-Carotene was solubilized within lipid droplets of emulsion that were then entrapped within rice starch hydrogels fabricated with different concentrations of xanthan gum. At a low concentration of xanthan gum (<0.5wt%), the viscous characteristics of the filled starch hydrogels increased. Furthermore, these hydrogels had a slower rate of lipid digestion than the β-carotene-loaded emulsion. As the concentration of xanthan gum was increased (to 1.0wt% and 2.0wt%), the filled starch hydrogels became more elastic gel-like than those without xanthan gum, and also had the fastest rate and highest final extent of lipid digestion. The addition of xanthan gum to the filled starch hydrogel lowered the bioaccessibility of β-carotene to varying degrees, depending on the xanthan gum concentration. The results obtained from this study can be useful in designing gel-like food products fortified with lipophilic nutraceuticals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Designing degradable hydrogels for orthogonal control of cell microenvironments

PubMed Central

Kharkar, Prathamesh M.

2013-01-01

Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness. However, thoughtful selection of hydrogel base materials, formation chemistries, and degradable moieties is necessary to achieve the appropriate level of property control and desired cellular response. In this review, hydrogel design considerations and materials for hydrogel preparation, ranging from natural polymers to synthetic polymers, are overviewed. Recent advances in chemical and physical methods to crosslink hydrogels are highlighted, as well as recent developments in controlling hydrogel degradation rates and modes of degradation. Special attention is given to spatial or temporal presentation of various biochemical and biophysical cues to modulate cell response in static (i.e., non-degradable) or dynamic (i.e., degradable) microenvironments. This review provides insight into the design of new cell-compatible, degradable hydrogels to understand and modulate cellular processes for various biomedical applications. PMID:23609001

Reinforcement of mono- and bi-layer poly(ethylene glycol) hydrogels with a fibrous collagen scaffold

PubMed Central

Kinneberg, K. R. C.; Nelson, A.; Stender, M.; Aziz, A. H.; Mozdzen, L. C.; Harley, B. A. C.; Bryant, S. J.; Ferguson, V. L.

2015-01-01

Biomaterial-based tissue engineering strategies hold great promise for osteochondral tissue repair. Yet significant challenges remain in joining highly dissimilar materials to achieve a biomimetic, mechanically robust design for repairing interfaces between soft tissue and bone. This study sought to improve interfacial properties and function in a bilayer, multi-phase hydrogel interpenetrated with a fibrous collagen scaffold. ‘Soft’ 10% (w/w) and ‘stiff’ 30% (w/w) PEGDM was formed into mono- or bilayer hydrogels possessing a sharp diffusional interface. Hydrogels were evaluated as single- (hydrogel only) or multi-phase (hydrogel+fibrous scaffold penetrating throughout the stiff layer and extending >500μm into the soft layer). Including a fibrous scaffold into both soft and stiff single-phase hydrogels significantly increased tangent modulus and toughness and decreased lateral expansion under compressive loading. In multi-phase hydrogels, finite element simulations predict substantially reduced stress and strain gradients across the soft—stiff hydrogel interface. When combining two low moduli constituent material, composites theory poorly predicts the observed, large modulus increases. These results suggest material structure associated with the fibrous scaffold penetrating within the PEG hydrogel as the major contributor to improved properties and function – the hydrogel bore compressive loads and the 3D fibrous scaffold was loaded in tension thus resisting lateral expansion. PMID:26001970

Biosynthetic hydrogels--studies on chemical and physical characteristics on long-term cellular response for tissue engineering.

PubMed

Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2014-07-01

Biosynthetic hydrogels can meet the drawbacks caused by natural and synthetic ones for biomedical applications. In the current article we present a novel biosynthetic alginate-poly(propylene fumarate) copolymer based chemically crosslinked hydrogel scaffolds for cardiac tissue engineering applications. Partially crosslinked PA hydrogel and fully cross linked PA-A hydrogel scaffolds were prepared. The influence of chemical and physical (morphology and architecture of hydrogel) characteristics on the long term cellular response was studied. Both these hydrogels were cytocompatible and showed no genotoxicity upon contact with fibroblast cells. Both PA and PA-A were able to resist deleterious effects of reactive oxygen species and sustain the viability of L929 cells. The hydrogel incubated oxidative stress induced cells were capable of maintaining the intra cellular reduced glutathione (GSH) expression to the normal level confirmed their protective effect. Relatively the PA hydrogel was found to be unstable in the cell culture medium. The PA-A hydrogel was able to withstand appreciable cyclic stretching. The cyclic stretching introduced complex macro and microarchitectural features with interconnected pores and more structured bound water which would provide long-term viability of around 250% after the 24th day of culture. All these qualities make PA-A hydrogel form a potent candidate for cardiac tissue engineering. © 2013 Wiley Periodicals, Inc.

Reinforcing the inner phase of the filled hydrogels with CNTs alters drug release properties and human keratinocyte morphology: A study on the gelatin- tamarind gum filled hydrogels.

PubMed

Maharana, Vivek; Gaur, Deepanjali; Nayak, Suraj K; Singh, Vinay K; Chakraborty, Subhabrata; Banerjee, Indranil; Ray, Sirsendu S; Anis, Arfat; Pal, Kunal

2017-11-01

The study reports the synthesis and characterization of gelatin-tamarind gum (TG) based filled hydrogels for drug delivery applications. In this study, three different types of carbon nanotubes (CNTs) were incorporated within the dispersed TG phase of the filled hydrogels. The prepared hydrogels were thoroughly characterised using bright field microscope, FESEM, FTIR spectroscopy, differential scanning calorimeter, and mechanical tester. The swelling and the drug (salicylic acid) release properties of the filled hydrogels were also evaluated. The micrographs revealed the formation of biphasic systems. The internal phase appeared as agglomerates, and the CNTs were confined within the dispersed TG phase. FTIR and XRD studies revealed that CNTs promoted associative interactions among the components of the hydrogel, which promoted the formation of large crystallite size. The mechanical study indicated better resistance to the breakdown of the architecture of the CNT-containing filled hydrogels. Drug release studies, both passive and iontophoretic, suggested that the non-Fickian diffusion of the drug was prevalent during its release from hydrogel matrices. The prepared hydrogels were cytocompatible with human keratinocytes. The results suggested the probable use of such hydrogels in wound healing, tissue engineering and drug delivery applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tough Hydrogel Robots: High-Speed, High-Force and Opto-sonically Invisible in Water

NASA Astrophysics Data System (ADS)

Zhao, Xuanhe

Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of tough hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. We invent a simple method capable of assembling physically-crosslinked hydrogel parts followed by covalent crosslinking to fabricate large-scale hydraulic hydrogel actuators and robots with robust bodies and interfaces. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owning to the anti-fatigue property of the hydrogel under moderate stresses. A multiscale theoretical framework has been developed to guide the design and optimization of the hydrogel robots. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and catching a live fish in water. The work was supported by NSF(No. CMMI- 1253495) and ONR (No. N00014-14-1-0528).

Controlling Mechanical Properties of Cell-Laden Hydrogels by Covalent Incorporation of Graphene Oxide

PubMed Central

Cha, Chaenyung; Shin, Su Ryon; Gao, Xiguang; Annabi, Nasim; Dokmeci, Mehmet R.; Tang, Xiaowu (Shirley); Khademhosseini, Ali

2013-01-01

Graphene-based materials are useful reinforcing agents to modify the mechanical properties of hydrogels. Here, we present an approach to covalently incorporate graphene oxide (GO) into hydrogels via radical copolymerization to enhance the dispersion and conjugation of GO sheets within the hydrogels. GO is chemically modified to present surface-grafted methacrylate groups (MeGO). In comparison to GO, higher concentrations of MeGO can be stably dispersed in a pre-gel solution containing methacrylated gelatin (GelMA) without aggregation or significant increase in viscosity. In addition, the resulting MeGO-GelMA hydrogels demonstrate a significant increase in fracture strength with increasing MeGO concentration. Interestingly, the rigidity of the hydrogels is not significantly affected by the covalently incorporated GO. Therefore, our approach can be used to enhance the structural integrity and resistance to fracture of the hydrogels without inadvertently affecting their rigidity, which is known to affect the behavior of encapsulated cells. The biocompatibility of MeGO-GelMA hydrogels is confirmed by measuring the viability and proliferation of the encapsulated fibroblasts. Overall, this study highlights the advantage of covalently incorporating GO into a hydrogel system, and improves the quality of cell-laden hydrogels. PMID:24127350

Construction and characterization of a pure protein hydrogel for drug delivery application.

PubMed

Xu, Xu; Xu, ZhaoKang; Yang, XiaoFeng; He, YanHao; Lin, Rong

2017-02-01

Injectable hydrogels have a variety of applications, including regenerative medicine, tissue engineering and controlled drug delivery. In this paper, we reported on a pure protein hydrogel based on tetrameric recombinant proteins for the potential drug delivery application. This protein hydrogel was formed instantly by simply mixing two recombinant proteins (ULD-TIP1 and ULD-GGGWRESAI) through the specific protein-peptide interaction. The protein hydrogel was characterized by rheology and scanning electron microscopy (SEM). In vitro cytotoxicity test indicated that the developed protein hydrogel had no apparent cytotoxicity against L-929 cells and HCEC cells after 48h incubation. The formed protein hydrogels was gradually degraded after incubation in phosphate buffered solution (PBS, pH=7.4) for a period of 144h study, as indicated by in vitro degradation test. Encapsulation of model drug (sodium diclofenac; DIC) were achieved by simple mixing of drugs with hydrogelator and the entrapped drugs was almost completely released from hydrogels within 24h via a diffusion manner. As a conclusion, the simple and mild preparation procedure and good biocompatibility of protein hydrogel would render its good promising candidate for drug delivery applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation, properties and biological application of pH-sensitive poly(ethylene oxide) (PEO) hydrogels grafted with acrylic acid(AAc) using gamma-ray irradiation

NASA Astrophysics Data System (ADS)

Nho, Young Chang; Mook Lim, Youn; Moo Lee, Young

2004-09-01

pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by γ-ray irradiation, and then grafting by AAc monomer onto the PEO hydrogels with the subsequent irradiation (radiation dose: 5-20 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. The in vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UV/VIS spectrophotometer. Insulin was loaded into freeze-dried hydrogels (7 mm×3 mm×2.5 mm) and administrated orally to healthy and diabetic Wistar rats. The oral administration of insulin-loaded hydrogels to Wistar rats decreased the blood glucose levels obviously for at least 4 h due to the absorption of insulin in the gastrointestinal tract.

Polyluminol/hydrogel composites as new electrochemiluminescent-active sensing layers.

PubMed

Leca-Bouvier, Béatrice D; Sassolas, Audrey; Blum, Loïc J

2014-09-01

This paper reports on electrochemiluminescent sensors and biosensors based on polyluminol/hydrogel composite sensing layers using chemical or biological membranes as hydrogel matrices. In this work, luminol is electropolymerized under near-neutral conditions onto screen-printed electrode (SPE)-supported hydrogel films. The working electrode coated with a hydrogel film is soaked in a solution containing monomeric luminol units, allowing the monomeric luminol units to diffuse inside the porous matrix to the electrode surface where they are electropolymerized by cyclic voltammetry (CV). Sensors and enzymatic biosensors for H2O2 and choline detection, respectively, have been developed, using choline oxidase (ChOD) as a model enzyme. In this case, hydrogel is used both as the enzymatic immobilization matrix and as a template for the electrosynthesis of polyluminol. The enzyme was immobilized by entrapment in the gel matrix during its formation before electropolymerization of the monomer. Several parameters have been optimized in terms of polymerization conditions, enzyme loading, and average pore size. Using calcium alginate or tetramethoxysilane (TMOS)-based silica as porous matrix, H2O2 and choline detection are reported down to micromolar concentrations with three orders of magnitude wide dynamic ranges starting from 4 × 10(-7) M. Polyluminol/hydrogel composites appear as suitable electrochemiluminescence (ECL)-active sensing layers for the design of new reagentless and disposable easy-to-use optical sensors and biosensors, using conventional TMOS-based silica gel or the more original and easier to handle calcium alginate, reported here for the first time in such a configuration, as the biocompatible hydrogel matrix.

Structure-Property Evaluation of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering

PubMed Central

Ekenseair, Adam K.; Boere, Kristel W. M.; Tzouanas, Stephanie N.; Vo, Tiffany N.; Kasper, F. Kurtis; Mikos, Antonios G.

2012-01-01

The impact of synthesis and solution formulation parameters on the swelling and mechanical properties of a novel class of thermally and chemically gelling hydrogels combining poly(N-isopropylacrylamide)-based thermogelling macromers containing pendant epoxy rings with polyamidoamine-based hydrophilic and degradable diamine crosslinking macromers was evaluated. Through variation of network hydrophilicity and capacity for chain rearrangement, the often problematic tendency of thermogelling hydrogels to undergo significant syneresis was addressed. The demonstrated ability to easily tune post-formation dimensional stability at both the synthesis and formulation stages represents a significant novel contribution towards efforts to utilize poly(N-isopropylacrylamide)-based polymers as injectable biomaterials. Furthermore, the cytocompatibility of the hydrogel system under relevant conditions was established, while demonstrating time- and dose-dependent cytotoxicity at high solution osmolality. Such injectable in situ forming degradable hydrogels with tunable water content are promising candidates for many tissue engineering applications, particularly for cell delivery to promote rapid tissue regeneration in non-load-bearing defects. PMID:22881074

Peritoneal adhesion prevention with a biodegradable and injectable N,O-carboxymethyl chitosan-aldehyde hyaluronic acid hydrogel in a rat repeated-injury model

PubMed Central

Song, Linjiang; Li, Ling; He, Tao; Wang, Ning; Yang, Suleixin; Yang, Xi; Zeng, Yan; Zhang, Wenli; Yang, Li; Wu, Qinjie; Gong, Changyang

2016-01-01

Postoperative peritoneal adhesion is one of the serious issues because it induces severe clinical disorders. In this study, we prepared biodegradable and injectable hydrogel composed of N,O-carboxymethyl chitosan (NOCC) and aldehyde hyaluronic acid (AHA), and assessed its anti-adhesion effect in a rigorous and severe recurrent adhesion model which is closer to clinical conditions. The flexible hydrogel, which gelated in 66 seconds at 37 °C, was cross-linked by the schiff base derived from the amino groups of NOCC and aldehyde groups in AHA. In vitro cytotoxicity test showed the hydrogel was non-toxic. In vitro and in vivo degradation examinations demonstrated the biodegradable and biocompatibility properties of the hydrogel. The hydrogel discs could prevent the invasion of fibroblasts, whereas fibroblasts encapsulated in the porous 3-dimensional hydrogels could grow and proliferate well. Furthermore, the hydrogel was applied to evaluate the anti-adhesion efficacy in a more rigorous recurrent adhesion model. Compared with normal saline group and commercial hyaluronic acid (HA) hydrogel, the NOCC-AHA hydrogel exhibited significant reduction of peritoneal adhesion. Compared to control group, the blood and abdominal lavage level of tPA was increased in NOCC-AHA hydrogel group. These findings suggested that NOCC-AHA hydrogel had a great potential to serve as an anti-adhesion candidate. PMID:27869192

Zwitterionic PEG-PC Hydrogels Modulate the Foreign Body Response in a Modulus-Dependent Manner.

PubMed

Jansen, Lauren E; Amer, Luke D; Chen, Esther Y-T; Nguyen, Thuy V; Saleh, Leila S; Emrick, Todd; Liu, Wendy F; Bryant, Stephanie J; Peyton, Shelly R

2018-05-15

Reducing the foreign body response (FBR) to implanted biomaterials will enhance their performance in tissue engineering. Poly(ethylene glycol) (PEG) hydrogels are increasingly popular for this application due to their low cost, ease of use, and the ability to tune their compliance via molecular weight and cross-linking densities. PEG hydrogels can elicit chronic inflammation in vivo, but recent evidence has suggested that extremely hydrophilic, zwitterionic materials and particles can evade the immune system. To combine the advantages of PEG-based hydrogels with the hydrophilicity of zwitterions, we synthesized hydrogels with comonomers PEG and the zwitterion phosphorylcholine (PC). Recent evidence suggests that stiff hydrogels elicit increased immune cell adhesion to hydrogels, which we attempted to reduce by increasing hydrogel hydrophilicity. Surprisingly, hydrogels with the highest amount of zwitterionic comonomer elicited the highest FBR. Lowering the hydrogel modulus (165 to 3 kPa), or PC content (20 to 0 wt %), mitigated this effect. A high density of macrophages was found at the surface of implants associated with a high FBR, and mass spectrometry analysis of the proteins adsorbed to these gels implicated extracellular matrix, immune response, and cell adhesion protein categories as drivers of macrophage recruitment. Overall, we show that modulus regulates macrophage adhesion to zwitterionic-PEG hydrogels, and demonstrate that chemical modifications to hydrogels should be studied in parallel with their physical properties to optimize implant design.

Peritoneal adhesion prevention with a biodegradable and injectable N,O-carboxymethyl chitosan-aldehyde hyaluronic acid hydrogel in a rat repeated-injury model

NASA Astrophysics Data System (ADS)

Song, Linjiang; Li, Ling; He, Tao; Wang, Ning; Yang, Suleixin; Yang, Xi; Zeng, Yan; Zhang, Wenli; Yang, Li; Wu, Qinjie; Gong, Changyang

2016-11-01

Postoperative peritoneal adhesion is one of the serious issues because it induces severe clinical disorders. In this study, we prepared biodegradable and injectable hydrogel composed of N,O-carboxymethyl chitosan (NOCC) and aldehyde hyaluronic acid (AHA), and assessed its anti-adhesion effect in a rigorous and severe recurrent adhesion model which is closer to clinical conditions. The flexible hydrogel, which gelated in 66 seconds at 37 °C, was cross-linked by the schiff base derived from the amino groups of NOCC and aldehyde groups in AHA. In vitro cytotoxicity test showed the hydrogel was non-toxic. In vitro and in vivo degradation examinations demonstrated the biodegradable and biocompatibility properties of the hydrogel. The hydrogel discs could prevent the invasion of fibroblasts, whereas fibroblasts encapsulated in the porous 3-dimensional hydrogels could grow and proliferate well. Furthermore, the hydrogel was applied to evaluate the anti-adhesion efficacy in a more rigorous recurrent adhesion model. Compared with normal saline group and commercial hyaluronic acid (HA) hydrogel, the NOCC-AHA hydrogel exhibited significant reduction of peritoneal adhesion. Compared to control group, the blood and abdominal lavage level of tPA was increased in NOCC-AHA hydrogel group. These findings suggested that NOCC-AHA hydrogel had a great potential to serve as an anti-adhesion candidate.

Characterization of elasticity and hydration of composite hydrogel based on collagen-iota carrageenan as a corneal tissue engineering

NASA Astrophysics Data System (ADS)

Rinawati, M.; Triastuti, J.; Pursetyo, K. T.

2018-04-01

The cornea is a refractive element of the eye that serves to continue the stimulation of light into the eye it has a clear, transparent, elastic and relatively thick tissue. Factors caused corneal blindness, are dystrophy, keratoconus, corneal scaring. Hydrogels can be made from polysaccharide derivatives that have gelation properties such as iota carrageenan. Therefore, it is a need to develop composite hydrogel based collagen-iota carragenan as an engineeried corneal tissue with high elasticity and hydration properties. Collagen hydrogel has a maximum water content an has equlibrium up to 40 %, less than the human cornea, 81 % and under normal hydration conditions, the human cornea can transmit 87 % of visible light. In addition, the refractive index on the surface of the cornea with air is 1.375-1.380. Based on this study, it is necessary to conduct research on the development and composition of hydrogel composite collagen-iota carrageen hydrogen based on. The best result was K5 (5:5) treatment, which has the equilibrium water content of 87.07 % and viscosity of 10.7346 Pa.s.

Hydrogel-based electrochemical sensor for non-invasive and continuous glucose monitoring

NASA Astrophysics Data System (ADS)

Park, Habeen; Lee, Ji-Young; Kim, Dong-Chul; Koh, Younggook; Cha, Junhoe

2017-07-01

Monitoring blood glucose level of diabetic patients is crucial in diabetes care from life threating complications. Selfmonitoring blood glucose (SMBG) that involves finger prick to draw blood samples into the measurement system is a widely-used method of routine measurement of blood glucose levels to date. SMBG includes, however, unavoidable pain problems resulting from the repetitive measurements. We hereby present a hydrogel-based electrochemical (H-EC) sensor to monitor the glucose level, non-invasively. Glucose oxidase (GOx) was immobilized in the disc-type hydroxyethyl methacrylate (HEMA) based hydrogel and kept intact in the hydrogel. Fast electron transfer mediated by Prussian blue (PB, hexacyanoferrate) generated efficient signal amplifications to facilitate the detection of the extracted glucose from the interstitial fluid. The linear response and the selectivity against glucose of the H-EC sensor were validated by chronoamperometry. For the practical use, the outcomes from the correlation of the extracted glucose concentration and the blood glucose value by on-body extraction, as well as the validation of the hydrogel-based electrochemical (H-EC) device, were applied to the on-body glucose monitoring.

Artificial Auricular Cartilage Using Silk Fibroin and Polyvinyl Alcohol Hydrogel

PubMed Central

Lee, Jung Min; Sultan, Md. Tipu; Kim, Soon Hee; Kumar, Vijay; Yeon, Yeung Kyu; Lee, Ok Joo; Park, Chan Hum

2017-01-01

Several methods for auricular cartilage engineering use tissue engineering techniques. However, an ideal method for engineering auricular cartilage has not been reported. To address this issue, we developed a strategy to engineer auricular cartilage using silk fibroin (SF) and polyvinyl alcohol (PVA) hydrogel. We constructed different hydrogels with various ratios of SF and PVA by using salt leaching, silicone mold casting, and freeze-thawing methods. We characterized each of the hydrogels in terms of the swelling ratio, tensile strength, pore size, thermal properties, morphologies, and chemical properties. Based on the cell viability results, we found a blended hydrogel composed of 50% PVA and 50% SF (P50/S50) to be the best hydrogel among the fabricated hydrogels. An intact 3D ear-shaped auricular cartilage formed six weeks after the subcutaneous implantation of a chondrocyte-seeded 3D ear-shaped P50/S50 hydrogel in rats. We observed mature cartilage with a typical lacunar structure both in vitro and in vivo via histological analysis. This study may have potential applications in auricular tissue engineering with a human ear-shaped hydrogel. PMID:28777314

Ask Dr. Sue.

ERIC Educational Resources Information Center

Aronson, Susan S.

1990-01-01

Infant and Child First Aid Training is recommended over CPR for child caregivers. Digital thermometers are considered more reliable, safer, and more versatile than other thermometers. Super-absorbent, disposable diapers are recommended as superior to cloth diapers for sanitary and health reasons. (SH)

Enabling Surgical Placement of Hydrogels through Achieving Paste-Like Rheological Behavior in Hydrogel Precursor Solutions

PubMed Central

Beck, Emily C.; Lohman, Brooke L.; Tabakh, Daniel B.; Kieweg, Sarah L.; Gehrke, Stevin H.; Berkland, Cory J.; Detamore, Michael S.

2015-01-01

Hydrogels are a promising class of materials for tissue regeneration, but they lack the ability to be molded into a defect site by a surgeon because hydrogel precursors are liquid solutions that are prone to leaking during placement. Therefore, although the main focus of hydrogel technology and developments are on hydrogels in their crosslinked form, our primary focus is on improving the fluid behavior of hydrogel precursor solutions. In this work, we introduce a method to achieve paste-like hydrogel precursor solutions by combining hyaluronic acid nanoparticles with traditional crosslinked hyaluronic acid hydrogels. Prior to crosslinking, the samples underwent rheological testing to assess yield stress and recovery using linear hyaluronic acid as a control. The experimental groups containing nanoparticles were the only solutions that exhibited a yield stress, demonstrating that the nanoparticulate rather than the linear form of hyaluronic acid was necessary to achieve paste-like behavior. The gels were also photocrosslinked and further characterized as solids, where it was demonstrated that the inclusion of nanoparticles did not adversely affect the compressive modulus and that encapsulated bone marrow-derived mesenchymal stem cells remained viable. Overall, this nanoparticle-based approach provides a platform hydrogel system that exhibits a yield stress prior to crosslinking, and can then be crosslinked into a hydrogel that is capable of encapsulating cells that remain viable. This behavior may hold significant impact for hydrogel applications where a paste-like behavior is desired in the hydrogel precursor solution. PMID:25691398

Stable environmentally sensitive cationic hydrogels for controlled delivery applications.

PubMed

Deo, Namita; Ruetsch, S; Ramaprasad, K R; Kamath, Y

2010-01-01

New thermosensitive, cationic hydrogels were synthesized by the dispersion copolymerization of N-isopropylacrylamide (NIPAM) and (3-acrylamidopropyl)trimethylammonium chloride (AAPTAC). In the polymerization protocol, an amide-based comonomer, (3-acrylamidopropyl)trimethylammonium chloride, was reacted as a new alternative monomer for introducing positive charges into the thermosensitive hydrogel. The hydrogels were synthesized without making any pH adjustment in the aqueous medium. These hydrogel particles exhibited colloidal stability in the pH range of 1.5 to 11.0, while similar cationic hydrogels were reported to be unstable at pHs higher than 6. The stronger cationic character of the selected comonomer provided higher colloidal stability to the poly(NIPAM-co-AAPTAC) hydrogels. Furthermore, these hydrogels displayed sensitivity towards temperature, pH, and salt concentration. Interestingly, the particle size of hydrogels was found to be decreased significantly with an increase in temperature and salt concentration. In addition, using pyrene fluorescence spectroscopy, it was established that the hydrophobicity/hydrophilicity of the hydrogel particles was largely controlled by both pH and temperature. The thermosensitive hydrogels reported in this paper may be suitable for delivering different actives for cosmetic and medical applications. Although direct application of these hydrogel particles in cosmetics has not been shown at this stage, the methodology of making them and controlling their absorption and release properties as a function of temperature and pH has been demonstrated. Furthermore, these hydrogels may also have applications in scavenging organic and inorganic toxics.

Properties and in vitro drug release of hyaluronic acid-hydroxyethyl cellulose hydrogels for transdermal delivery of isoliquiritigenin.

PubMed

Kong, Bong Ju; Kim, Ayoung; Park, Soo Nam

2016-08-20

In the present study, the properties of hydrogel systems based on hyaluronic acid (HA)-hydroxyethyl cellulose (HEC) were investigated for effective transdermal delivery of isoliquiritigenin (ILTG). Hydrogels were synthesized by chemical cross-linking, and network structures were characterised using scanning electron microscopy (SEM) and surface area analyser. Texture properties and swelling of HA-HEC hydrogels were found to be closely linked to cross-linker concentration and swelling medium. Water in HA-HEC hydrogels was found to exist mostly in the form of free water. The viscoelasticity and the network stabilization of the hydrogels were analysed via rheological studies. The release kinetics of the hydrogel followed Fickian diffusion mechanism. In an in vitro skin penetration study, the system substantially improved the delivery of ILTG into the skin. These results indicate that the hydrogel system composed of HA and HEC has potential as a transdermal delivery system, with cross-linking density and the swelling medium influencing the properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of a novel cationic hydrogel base on salecan-g-PMAPTAC.

PubMed

Wei, Wei; Qi, Xiaoliang; Li, Junjian; Zhong, Yin; Zuo, Gancheng; Pan, Xihao; Su, Ting; Zhang, Jianfa; Dong, Wei

2017-08-01

Salecan is a biological macromolecular and biocompatible polysaccharide that has been investigated for recent years. Herein, we report a novel cationic hydrogel fabricated by graft-polymerizing 3-(methacryloylamino)propyl-trimethylammonium chloride (MAPTAC) onto salecan chains. The obtained hydrogels were transparent, solid-elastic, macro-porous, ion-sensitive, and non-cytotoxic. The swelling ratios increased with salecan content, while mechanical strength does the opposite. Moreover, drug delivery test was studied as a potential application. Diclofenac sodium (DS) and insulin were selected as model drugs. Interestingly, in drug loading process, DS molecules exhibited highly affinity to these cationic hydrogels. Almost all the DS molecules in loading solution were absorbed and spread into the hydrogel. For drug release profiles, insulin-loaded hydrogel showed an initial rapid release and a sustained release. As a comparison, DS-loaded hydrogel exhibited a more sustained release profile. Results suggested salecan-g-PMAPTAC hydrogel could be a good candidate for anionic drug loading and delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanically enhanced nested-network hydrogels as a coating material for biomedical devices.

PubMed

Wang, Zhengmu; Zhang, Hongbin; Chu, Axel J; Jackson, John; Lin, Karen; Lim, Chinten James; Lange, Dirk; Chiao, Mu

2018-04-01

Well-organized composite formations such as hierarchical nested-network (NN) structure in bone tissue and reticular connective tissue present remarkable mechanical strength and play a crucial role in achieving physical and biological functions for living organisms. Inspired by these delicate microstructures in nature, an analogous scaffold of double network hydrogel was fabricated by creating a poly(2-hydroxyethyl methacrylate) (pHEMA) network in the porous structure of alginate hydrogels. The resulting hydrogel possessed hierarchical NN structure and showed significantly improved mechanical strength but still maintained high elasticity comparable to soft tissues due to a mutual strengthening effect between the two networks. The tough hydrogel is also self-lubricated, exhibiting a surface friction coefficient comparable with polydimethylsiloxane (PDMS) substrates lubricated by a commercial aqueous lubricant (K-Y Jelly) and other low surface friction hydrogels. Additional properties of this hydrogel include high hydrophilicity, good biocompatibility, tunable cell adhesion and bacterial resistance after incorporation of silver nanoparticles. Firm bonding of the hydrogel on silicone substrates could be achieved through facile chemical modification, thus enabling the use of this hydrogel as a versatile coating material for biomedical applications. In this study, we developed a tough hydrogel by crosslinking HEMA monomers in alginate hydrogels and forming a well-organized structure of hierarchical nested network (NN). Different from most reported stretchable alginate-based hydrogels, the NN hydrogel shows higher compressive strength but retains comparable softness to alginate counterparts. This work further demonstrated the good integration of the tough hydrogel with silicone substrates through chemical modification and micropillar structures. Other properties including surface friction, biocompatibility and bacterial resistance were investigated and the hydrogel shows a great promise as a versatile coating material for biomedical applications. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

In vitro drug release behavior from a novel thermosensitive composite hydrogel based on Pluronic f127 and poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) copolymer

PubMed Central

Gong, Chang Yang; Shi, Shuai; Dong, Peng Wei; Zheng, Xiu Ling; Fu, Shao Zhi; Guo, Gang; Yang, Jing Liang; Wei, Yu Quan; Qian, Zhi Yong

2009-01-01

Background Most conventional methods for delivering chemotherapeutic agents fail to achieve therapeutic concentrations of drugs, despite reaching toxic systemic levels. Novel controlled drug delivery systems are designed to deliver drugs at predetermined rates for predefined periods at the target organ and overcome the shortcomings of conventional drug formulations therefore could diminish the side effects and improve the life quality of the patients. Thus, a suitable controlled drug delivery system is extremely important for chemotherapy. Results A novel biodegradable thermosensitive composite hydrogel, based on poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) and Pluronic F127 copolymer, was successfully prepared in this work, which underwent thermosensitive sol-gel-sol transition. And it was flowing sol at ambient temperature but became non-flowing gel at body temperature. By varying the composition, sol-gel-sol transition and in vitro drug release behavior of the composite hydrogel could be adjusted. Cytotoxicity of the composite hydrogel was conducted by cell viability assay using human HEK293 cells. The 293 cell viability of composite hydrogel copolymers were yet higher than 71.4%, even when the input copolymers were 500 μg per well. Vitamin B12 (VB12), honokiol (HK), and bovine serum albumin (BSA) were used as model drugs to investigate the in vitro release behavior of hydrophilic small molecular drug, hydrophobic small molecular drug, and protein drug from the composite hydrogel respectively. All the above-mentioned drugs in this work could be released slowly from composite hydrogel in an extended period. Chemical composition of composite hydrogel, initial drug loading, and hydrogel concentration substantially affected the drug release behavior. The higher Pluronic F127 content, lower initial drug loading amount, or lower hydrogel concentration resulted in higher cumulative release rate. Conclusion The results showed that composite hydrogel prepared in this paper were biocompatible with low cell cytotoxicity, and the drugs in this work could be released slowly from composite hydrogel in an extended period, which suggested that the composite hydrogel might have great potential applications in biomedical fields. PMID:19210779

Stress relaxing hyaluronic acid-collagen hydrogels promote cell spreading, fiber remodeling, and focal adhesion formation in 3D cell culture.

PubMed

Lou, Junzhe; Stowers, Ryan; Nam, Sungmin; Xia, Yan; Chaudhuri, Ovijit

2018-02-01

The physical and architectural cues of the extracellular matrix (ECM) play a critical role in regulating important cellular functions such as spreading, migration, proliferation, and differentiation. Natural ECM is a complex viscoelastic scaffold composed of various distinct components that are often organized into a fibrillar microstructure. Hydrogels are frequently used as synthetic ECMs for 3D cell culture, but are typically elastic, due to covalent crosslinking, and non-fibrillar. Recent work has revealed the importance of stress relaxation in viscoelastic hydrogels in regulating biological processes such as spreading and differentiation, but these studies all utilize synthetic ECM hydrogels that are non-fibrillar. Key mechanotransduction events, such as focal adhesion formation, have only been observed in fibrillar networks in 3D culture to date. Here we present an interpenetrating network (IPN) hydrogel system based on HA crosslinked with dynamic covalent bonds and collagen I that captures the viscoelasticity and fibrillarity of ECM in tissues. The IPN hydrogels exhibit two distinct processes in stress relaxation, one from collagen and the other from HA crosslinking dynamics. Stress relaxation in the IPN hydrogels can be tuned by modulating HA crosslinker affinity, molecular weight of the HA, or HA concentration. Faster relaxation in the IPN hydrogels promotes cell spreading, fiber remodeling, and focal adhesion (FA) formation - behaviors often inhibited in other hydrogel-based materials in 3D culture. This study presents a new, broadly adaptable materials platform for mimicking key ECM features of viscoelasticity and fibrillarity in hydrogels for 3D cell culture and sheds light on how these mechanical and structural cues regulate cell behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes

NASA Astrophysics Data System (ADS)

Zhang, Lijie; Rodriguez, Jose; Raez, Jose; Myles, Andrew J.; Fenniri, Hicham; Webster, Thomas J.

2009-04-01

Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml-1 HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites make them promising candidates for further study for bone tissue engineering applications.

Programmable display of DNA-protein chimeras for controlling cell-hydrogel interactions via reversible intermolecular hybridization.

PubMed

Zhang, Zhaoyang; Li, Shihui; Chen, Niancao; Yang, Cheng; Wang, Yong

2013-04-08

Extensive studies have been recently carried out to achieve dynamic control of cell-material interactions primarily through physicochemical stimulation. The purpose of this study was to apply reversible intermolecular hybridization to program cell-hydrogel interactions in physiological conditions based on DNA-antibody chimeras and complementary oligonucleotides. The results showed that DNA oligonucleotides could be captured to and released from the immobilizing DNA-functionalized hydrogels with high specificity via DNA hybridization. Accordingly, DNA-antibody chimeras were captured to the hydrogels, successfully inducing specific cell attachment. The cell attachment to the hydrogels reached the plateau at approximately half an hour after the functionalized hydrogels and the cells were incubated together. The attached cells were rapidly released from the bound hydrogels when triggering complementary oligonucleotides were introduced to the system. However, the capability of the triggering complementary oligonucleotides in releasing cells was affected by the length of intermolecular hybridization. The length needed to be at least more than 20 base pairs in the current experimental setting. Notably, because the procedure of intermolecular hybridization did not involve any harsh condition, the released cells maintained the same viability as that of the cultured cells. The functionalized hydrogels also exhibited the potential to catch and release cells repeatedly. Therefore, this study demonstrates that it is promising to regulate cell-material interactions dynamically through the DNA-programmed display of DNA-protein chimeras.

Synthesis, Characterization, and Acute Oral Toxicity Evaluation of pH-Sensitive Hydrogel Based on MPEG, Poly(ε-caprolactone), and Itaconic Acid

PubMed Central

Tan, Liwei; Song, Jia; Luo, Feng

2013-01-01

A kind of chemically cross-linked pH-sensitive hydrogels based on methoxyl poly(ethylene glycol)-poly(caprolactone)-acryloyl chloride (MPEG-PCL-AC, PECA), poly(ethylene glycol) methyl ether methacrylate (MPEGMA, MEG), N,N-methylenebisacrylamide (BIS), and itaconic acid (IA) were prepared without using any organic solvent by heat-initiated free radical method. The obtained macromonomers and hydrogels were characterized by 1H NMR and FT-IR, respectively. Morphology study of hydrogels was also investigated in this paper, and it showed that the hydrogels had good pH-sensitivity. The acute toxicity test and histopathological study were conducted in BALB/c mice. The results indicated that the maximum tolerance dose of the hydrogel was higher than 10000 mg/kg body weight. No morality or signs of toxicity were observed during the whole 7-day observation period. Compared to the control groups, there were no important adverse effects in the variables of hematology routine test and serum chemistry analysis both in male or female treatment group. Histopathological study also did not show any significant lesions, including heart, liver, lung, spleen, kidney, stomach, intestine, and testis. All the results demonstrated that this hydrogel was nontoxic after gavage. Thus, the hydrogel might be the biocompatible potential candidate for oral drug delivery system. PMID:24364030

Integrating valve-inspired design features into poly(ethylene glycol) hydrogel scaffolds for heart valve tissue engineering.

PubMed

Zhang, Xing; Xu, Bin; Puperi, Daniel S; Yonezawa, Aline L; Wu, Yan; Tseng, Hubert; Cuchiara, Maude L; West, Jennifer L; Grande-Allen, K Jane

2015-03-01

The development of advanced scaffolds that recapitulate the anisotropic mechanical behavior and biological functions of the extracellular matrix in leaflets would be transformative for heart valve tissue engineering. In this study, anisotropic mechanical properties were established in poly(ethylene glycol) (PEG) hydrogels by crosslinking stripes of 3.4 kDa PEG diacrylate (PEGDA) within 20 kDa PEGDA base hydrogels using a photolithographic patterning method. Varying the stripe width and spacing resulted in a tensile elastic modulus parallel to the stripes that was 4.1-6.8 times greater than that in the perpendicular direction, comparable to the degree of anisotropy between the circumferential and radial orientations in native valve leaflets. Biomimetic PEG-peptide hydrogels were prepared by tethering the cell-adhesive peptide RGDS and incorporating the collagenase-degradable peptide PQ (GGGPQG↓IWGQGK) into the polymer network. The specific amounts of RGDS and PEG-PQ within the resulting hydrogels influenced the elongation, de novo extracellular matrix deposition and hydrogel degradation behavior of encapsulated valvular interstitial cells (VICs). In addition, the morphology and activation of VICs grown atop PEG hydrogels could be modulated by controlling the concentration or micro-patterning profile of PEG-RGDS. These results are promising for the fabrication of PEG-based hydrogels using anatomically and biologically inspired scaffold design features for heart valve tissue engineering. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Smart hydrogel-functionalized textile system with moisture management property for skin application

NASA Astrophysics Data System (ADS)

Wang, Xiaowen; Hu, Huawen; Yang, Zongyue; He, Liang; Kong, Yeeyee; Fei, Bin; Xin, John H.

2014-12-01

In this study, a functional textile-based material for topical skin application was fabricated by coating a thermoresponsive hydrogel onto one side of absorbent nonwoven fabric. The thermoresponsive hydrogel was synthesized easily through coupling of poly (ethylene glycol) (PEG) and poly (ɛ-caprolactone) (PCL) with hexamethylene diisocyanate (HMDI) as a chemical linker. The chemical structure of the as-prepared triblock copolymer hydrogel was unraveled by FTIR and 1H NMR analysis. The hydrogel showed a temperature-triggered sol-gel transition behavior and high potential for use as drug controlled release. When the surrounding temperature was close to the skin temperature of around 34 °C, it became a moisture management system where the liquids including sweat, blood, and other body fluids can be transported unidirectionally from one fabric side with the hydrophobic hydrogel coating to the untreated opposite side. This thereby showed that the thermoresponsive hydrogel-coated textile materials had a function to keep topical skin area clean, breathable, and comfortable, thus suggesting a great potential and significance for long-term skin treatment application. The structure and surface morphology of the thermoresponsive hydrogel, in vitro drug release behavior, and the mechanism of unidirectional water transport were investigated in detail. Our success in preparation of the functional textile composites will pave the way for development of various polymer- or textile-based functional materials that are applicable in the real world.

Formulation of sage essential oil (Salvia officinalis, L.) monoterpenes into chitosan hydrogels and permeation study with GC-MS analysis.

PubMed

Kodadová, Alexandra; Vitková, Zuzana; Herdová, Petra; Ťažký, Anton; Oremusová, Jarmila; Grančai, Daniel; Mikuš, Peter

2015-01-01

This study deals with the formulation of natural drugs into hydrogels. For the first time, compounds from the sage essential oil were formulated into chitosan hydrogels. A sample preparation procedure for hydrophobic volatile analytes present in a hydrophilic water matrix along with an analytical method based on the gas chromatography coupled with the mass spectrometry (GC-MS) was developed and applied for the evaluation of the identity and quantity of essential oil components in the hydrogels and saline samples. The experimental results revealed that the chitosan hydrogels are suitable for the formulation of sage essential oil. The monoterpene release can be effectively controlled by both chitosan and caffeine concentration in the hydrogels. Permeation experiment, based on a hydrogel with the optimized composition [3.5% (w/w) sage essential oil, 2.0% (w/w) caffeine, 2.5% (w/w) chitosan and 0.1% (w/w) Tween-80] in donor compartment, saline solution in acceptor compartment, and semi-permeable cellophane membrane, demonstrated the useful permeation selectivity. Here, (according to lipophilicity) an enhanced permeation of the bicyclic monoterpenes with antiflogistic and antiseptic properties (eucalyptol, camphor and borneol) and, at the same time, suppressed permeation of toxic thujone (not exceeding its permitted applicable concentration) was observed. These properties highlight the pharmaceutical importance of the developed chitosan hydrogel formulating sage essential oil in the dermal applications.

Development of CMC hydrogels loaded with silver nano-particles for medical applications.

PubMed

Hebeish, Ali; Hashem, M; El-Hady, M M Abd; Sharaf, S

2013-01-30

Innovative CMC-based hydrogels with great potentials for usage in medical area were principally synthesized as per two strategies .The first involved reaction of epichlorohydrin in alkaline medium containing silver nitrate to yield silver nano-particles (AgNPs)-loaded CMC hydrogel. While CMC acted as stabilizing for AgNPs, trisodium citrate was added to the reaction medium to assist CMC in establishing reduction of Ag(+) to AgNPs. The second strategy entailed preparation of CMC hydrogel which assists the in situ preparation of AgNPs under the same conditions. In both strategies, factors affecting the characterization of AgNPs-loaded CMC hydrogels were studied. Analysis and characterization of the so obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, EDX, UV-vis spectrophotometer and TEM. Antimicrobial activity of the hydrogels was examined and mechanisms involved in their synthesis were reported. Copyright © 2012 Elsevier Ltd. All rights reserved.

Rationally designed synthetic protein hydrogels with predictable mechanical properties.

PubMed

Wu, Junhua; Li, Pengfei; Dong, Chenling; Jiang, Heting; Bin Xue; Gao, Xiang; Qin, Meng; Wang, Wei; Bin Chen; Cao, Yi

2018-02-12

Designing synthetic protein hydrogels with tailored mechanical properties similar to naturally occurring tissues is an eternal pursuit in tissue engineering and stem cell and cancer research. However, it remains challenging to correlate the mechanical properties of protein hydrogels with the nanomechanics of individual building blocks. Here we use single-molecule force spectroscopy, protein engineering and theoretical modeling to prove that the mechanical properties of protein hydrogels are predictable based on the mechanical hierarchy of the cross-linkers and the load-bearing modules at the molecular level. These findings provide a framework for rationally designing protein hydrogels with independently tunable elasticity, extensibility, toughness and self-healing. Using this principle, we demonstrate the engineering of self-healable muscle-mimicking hydrogels that can significantly dissipate energy through protein unfolding. We expect that this principle can be generalized for the construction of protein hydrogels with customized mechanical properties for biomedical applications.

Reusable self-healing hydrogels realized via in situ polymerization.

PubMed

Vivek, Balachandran; Prasad, Edamana

2015-04-09

In this work, a self-healing hydrogel has been prepared using in situ polymerization of acrylic acid and acrylamide in the presence of glycogen. The hydrogel was characterized using NMR, SEM, FT-IR, rheology, and dynamic light scattering (DLS) studies. The developed hydrogel exhibits self-healing properties at neutral pH, high swelling ability, high elasticity, and excellent mechanical strength. The hydrogel exhibits modulus values (G', G″) as high as 10(6) Pa and shows an exceptionally high degree of swelling ratio (∼3.5 × 10(3)). Further, the polymer based hydrogel adsorbs toxic metal ions (Cd(2+), Pb(2+), and Hg(2+)) and organic dyes (methylene blue and methyl orange) from contaminated water with remarkable efficiency (90-98%). The mechanistic analysis indicated the presence of pseudo-second-order reaction kinetics. The reusability of the hydrogel has been demonstrated by repeating the adsorption-desorption process over five cycles with identical results in the adsorption efficiency.

A study in the adsorption of Fe(2+) and NO(3)(-) on pine needles based hydrogels.

PubMed

Chauhan, Ghanshyam S; Chauhan, Sandeep; Kumar, Sunil; Kumari, Anita

2008-09-01

Novel supports for use as cation and anion adsorbents were prepared from lignocellulosics using pine needles and their carboxymethylated forms by network/hydrogel formation with acrylamide and N,N-methylene bisacrylamide. The hydrogels thus prepared were further functionalized by partial alkaline hydrolysis with 0.5 N NaOH and were characterized by FTIR, SEM and nitrogen analysis. Adsorption of Fe(2+) on these hydrogels was carried as a function of time, temperature, pH and ionic strength. The hydrogel having the maximum adsorption capacity was loaded with Fe(2+) at the conditions those afforded maximum uptake and was used as novel anionic adsorbent for NO(3)(-). The water uptake capacities and biodegradability of the hydrogels before and after the ion loading was studied to evaluate the possible end-uses of these hydrogels as alternate materials in the removal of ionic species from water.

Time-dependent chemo-electro-mechanical behavior of hydrogel-based structures

NASA Astrophysics Data System (ADS)

Leichsenring, Peter; Wallmersperger, Thomas

2018-03-01

Charged hydrogels are ionic polymer gels and belong to the class of smart materials. These gels are multiphasic materials which consist of a solid phase, a fluid phase and an ionic phase. Due to the presence of bound charges these materials are stimuli-responsive to electrical or chemical loads. The application of electrical or chemical stimuli as well as mechanical loads lead to a viscoelastic response. On the macroscopic scale, the response is governed by a local reversible release or absorption of water which, in turn, leads to a local decrease or increase of mass and a respective volume change. Furthermore, the chemo-electro-mechanical equilibrium of a hydrogel depends on the chemical composition of the gel and the surrounding solution bath. Due to the presence of bound charges in the hydrogel, this system can be understood as an osmotic cell where differences in the concentration of mobile ions in the gel and solution domain lead to an osmotic pressure difference. In the present work, a continuum-based numerical model is presented in order to describe the time-dependent swelling behavior of hydrogels. The numerical model is based on the Theory of Porous Media and captures the fluid-solid, fluid-ion and ion-ion interactions. As a direct consequence of the chemo-electro-mechanical equilibrium, the corresponding boundary conditions are defined following the equilibrium conditions. For the interaction of the hydrogel with surrounding mechanical structures, also respective jump condtions are formulated. Finaly, numerical results of the time-dependent behavior of a hydrogel-based chemo-sensor will be presented.

Mechanical Testing of Hydrogels in Cartilage Tissue Engineering: Beyond the Compressive Modulus

PubMed Central

Xiao, Yinghua; Friis, Elizabeth A.; Gehrke, Stevin H.

2013-01-01

Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context. PMID:23448091

Biological hydrogels as selective diffusion barriers.

PubMed

Lieleg, Oliver; Ribbeck, Katharina

2011-09-01

The controlled exchange of molecules between organelles, cells, or organisms and their environment is crucial for life. Biological gels such as mucus, the extracellular matrix (ECM), and the biopolymer barrier within the nuclear pore are well suited to achieve such a selective exchange, allowing passage of particular molecules while rejecting many others. Although hydrogel-based filters are integral parts of biology, clear concepts of how their barrier function is controlled at a microscopic level are still missing. We summarize here our current understanding of how selective filtering is established by different biopolymer-based hydrogels. We ask if the modulation of microscopic particle transport in biological hydrogels is based on a generic filtering principle which employs biochemical/biophysical interactions with the filtered molecules rather than size-exclusion effects. Copyright © 2011 Elsevier Ltd. All rights reserved.

Bioorthogonal in Situ Hydrogels Based on Polyether Polyols for New Biosensor Materials with High Sensitivity.

PubMed

Herrmann, Anna; Kaufmann, Lena; Dey, Pradip; Haag, Rainer; Schedler, Uwe

2018-04-04

Both noncovalent and covalent encapsulations of active biomolecules, for example, proteins and oligonucleotides, for a new biosensor matrix in an in situ bioorthogonal hydrogel formation via a strain-promoted azide-alkyne cycloaddition reaction were investigated. Unspecific interaction between the gel and the biomolecules as well as protein denaturation was prevented by the bioorthogonal gel components, which ensure a uniform aqueous environment in the hydrogel network. No leaching of the active biomolecules was observed. Additionally, a much higher and also adjustable loading of biomolecules in the hydrogel matrix was achieved compared to conventional biosensor surfaces, where the sensor molecules are immobilized on monolayers (2D surfaces) or brushlike structures (3D surfaces). Spotting experiments of the hydrogel confirm the possibility to use this new surface for microarray-based multiplex applications which require very high signal-to-noise ratios.

Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhudesai, S. A., E-mail: swapnil@barc.gov.in; Mitra, S.; Mukhopadhyay, R.

2015-06-24

Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D{sub 2}O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by amore » model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10{sup −5} cm{sup 2}/sec.« less

Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

NASA Astrophysics Data System (ADS)

Prabhudesai, S. A.; Lawrence, Mathias B.; Mitra, S.; Desa, J. A. E.; Mukhopadhyay, R.

2015-06-01

Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D2O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10-5 cm2/sec.

Viscoelastic Properties and Morphology of Mumio-based Medicated Hydrogels

NASA Astrophysics Data System (ADS)

Zandraa, Oyunchimeg; Jelínková, Lenka; Roy, Niladri; Sáha, Tomáš; Kitano, Takeshi; Saha, Nabanita

2011-07-01

Novel medicated hydrogels were prepared (by moist heat treatment) with PVA, agar, mumio, mare's milk (MM), seabuckthorn oil (SB oil) and salicylic acid (SA) for wound dressing/healing application. Scanning electron micrographs (SEM) show highly porous structure of these hydrogels. The swelling behaviour of the hydrogels in physiological solution displays remarkable liquid absorption property. The knowledge obtained from rheological investigations of these-systems may be highly useful for the characterization of the newly developed topical formulations. In the present study, an oscillation frequency sweep test was used for the evaluation of storage modulus (G'), loss modulus (G″), and complex viscosity (η*) of five different formulations, over an angular frequency range from 0.1 to 100 rad.s-1. The influence of healing agents and swelling effect on the rheological properties of mumio-based medicated hydrogels was investigated to judge its application on uneven surface of body.

Multifunctional hydrogel nano-probes for atomic force microscopy

PubMed Central

Lee, Jae Seol; Song, Jungki; Kim, Seong Oh; Kim, Seokbeom; Lee, Wooju; Jackman, Joshua A.; Kim, Dongchoul; Cho, Nam-Joon; Lee, Jungchul

2016-01-01

Since the invention of the atomic force microscope (AFM) three decades ago, there have been numerous advances in its measurement capabilities. Curiously, throughout these developments, the fundamental nature of the force-sensing probe—the key actuating element—has remained largely unchanged. It is produced by long-established microfabrication etching strategies and typically composed of silicon-based materials. Here, we report a new class of photopolymerizable hydrogel nano-probes that are produced by bottom-up fabrication with compressible replica moulding. The hydrogel probes demonstrate excellent capabilities for AFM imaging and force measurement applications while enabling programmable, multifunctional capabilities based on compositionally adjustable mechanical properties and facile encapsulation of various nanomaterials. Taken together, the simple, fast and affordable manufacturing route and multifunctional capabilities of hydrogel AFM nano-probes highlight the potential of soft matter mechanical transducers in nanotechnology applications. The fabrication scheme can also be readily utilized to prepare hydrogel cantilevers, including in parallel arrays, for nanomechanical sensor devices. PMID:27199165

Lipophilic super-absorbent polymer gels as surface cleaners for oil and grease

USDA-ARS?s Scientific Manuscript database

Increasingly stringent environmental regulations on volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) demand the development of disruptive technologies for cleaning weapons systems and platforms. Currently employed techniques such as vapor degreasing, solvent, aqueous, or blast ...

Tuning the Mechanical Properties of a DNA Hydrogel in Three Phases Based on ATP Aptamer.

PubMed

Liu, Hengyuan; Cao, Tianyang; Xu, Yun; Dong, Yuanchen; Liu, Dongsheng

2018-05-31

By integrating ATP aptamer into the linker DNA, a novel DNA hydrogel was designed, with mechanical properties that could be tuned into three phases. Based on the unique interaction between ATP and its aptamer, the mechanical strength of the hydrogel increased from 204 Pa to 380 Pa after adding ATP. Furthermore, with the addition of the complementary sequence to the ATP aptamer, the mechanical strength could be increased to 570 Pa.

Synthesis and Primary Characterization of Self-Assembled Peptide-Based Hydrogels

PubMed Central

Nagarkar, Radhika P.; Schneider, Joel P.

2009-01-01

Summary Hydrogels based on peptide self-assembly form an important class of biomaterials that find application in tissue engineering and drug delivery. It is essential to prepare peptides with high purity to achieve batch-to-batch consistency affording hydrogels with reproducible properties. Automated solid-phase peptide synthesis coupled with optimized Fmoc (9-fluorenylmethoxycarbonyl) chemistry to obtain peptides in high yield and purity is discussed. Details of isolating a desired peptide from crude synthetic mixtures and assessment of the peptide’s final purity by high-performance liquid chromatography and mass spectrometry are provided. Beyond the practical importance of synthesis and primary characterization, techniques used to investigate the properties of hydrogels are briefly discussed. PMID:19031061

Molecular dynamics studies of polyurethane nanocomposite hydrogels

NASA Astrophysics Data System (ADS)

Strankowska, J.; Piszczyk, Ł.; Strankowski, M.; Danowska, M.; Szutkowski, K.; Jurga, S.; Kwela, J.

2013-10-01

Polyurethane PEO-based hydrogels have a broad range of biomedical applicability. They are attractive for drug-controlled delivery systems, surgical implants and wound healing dressings. In this study, a PEO based polyurethane hydrogels containing Cloisite® 30B, an organically modified clay mineral, was synthesized. Structure of nanocomposite hydrogels was determined using XRD technique. Its molecular dynamics was studied by means of NMR spectroscopy, DMA and DSC analysis. The mechanical properties and thermal stability of the systems were improved by incorporation of clay and controlled by varying the clay content in polymeric matrix. Molecular dynamics of polymer chains depends on interaction of Cloisite® 30B nanoparticles with soft segments of polyurethanes. The characteristic nanosize effect is observed.

Effects of Mechanical Constraint on the Performance of Fluorescent Hydrogel-based Fiber Optic Sensors

NASA Astrophysics Data System (ADS)

Jukl, Jennifer Marie

Although biosensor technology is a broad and well-studied field, the progress of many novel sensor technologies faces challenges. These challenges range from simple design considerations to fundamental issues with the concept or approach. One of the most active fields of sensor research integrates fiber optics with specially engineered fluorescent molecules. This type of sensor typically utilizes a porous polymer or porous glass substrate to entrap the fluorescent (or fluorescently-tagged) molecule. Porous polymer hydrogels are generally favored due to their ease of fabrication, low cost, adaptability, and biocompatibility. While hydrogels are ideal for both functional molecule suspension and fluid diffusion, their porosity and hydrophilicity are not always advantageous. The largest drawback of these properties is the hydrogel swelling they produce and the resulting geometric changes. This project investigated the limitations of fluorescent hydrogel-based sensors and the effects of unpredictable structural changes hydrogels undergo during typical, unrestrained swelling. The significance of covalent incorporation of the sensing fluorophore into the hydrogel matrix is also explored. Leaching tests were conducted using polyacrylamide (PAm) hydrogels which were impregnated with one of two pH sensitive fluorophores, one which bonded covalently with the hydrogel matrix during polymerization (fluorescein o-acrylate), and one which did not (fluorescein sodium). Once determined to be effective, the covalently bonding fluorophore was used to create constrained-dimension fluorescent pH sensors. These sensors were tested for effectiveness and reproducibility. All data was collected using a laboratory grade optical fibers, a USB spectrometer, and SpectraSuite software (Ocean Optics, 2010) unless otherwise specified.

Hybrid microscaffold-based 3D bioprinting of multi-cellular constructs with high compressive strength: A new biofabrication strategy

PubMed Central

Tan, Yu Jun; Tan, Xipeng; Yeong, Wai Yee; Tor, Shu Beng

2016-01-01

A hybrid 3D bioprinting approach using porous microscaffolds and extrusion-based printing method is presented. Bioink constitutes of cell-laden poly(D,L-lactic-co-glycolic acid) (PLGA) porous microspheres with thin encapsulation of agarose-collagen composite hydrogel (AC hydrogel). Highly porous microspheres enable cells to adhere and proliferate before printing. Meanwhile, AC hydrogel allows a smooth delivery of cell-laden microspheres (CLMs), with immediate gelation of construct upon printing on cold build platform. Collagen fibrils were formed in the AC hydrogel during culture at body temperature, improving the cell affinity and spreading compared to pure agarose hydrogel. Cells were proven to proliferate in the bioink and the bioprinted construct. High cell viability up to 14 days was observed. The compressive strength of the bioink is more than 100 times superior to those of pure AC hydrogel. A potential alternative in tissue engineering of tissue replacements and biological models is made possible by combining the advantages of the conventional solid scaffolds with the new 3D bioprinting technology. PMID:27966623

Highly Swellable, Dual-Responsive Hydrogels Based on PNIPAM and Redox Active Poly(ferrocenylsilane) Poly(ionic liquid)s: Synthesis, Structure, and Properties.

PubMed

Feng, Xueling; Zhang, Kaihuan; Chen, Peng; Sui, Xiaofeng; Hempenius, Mark A; Liedberg, Bo; Vancso, G Julius

2016-12-01

Highly swellable, dual-responsive hydrogels, consisting of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) based poly(ionic liquid)s (PILs) are formed by photo-polymerization. PFS chains bearing cross-linkable vinylimidazolium (VIm) side groups are copolymerized with NIPAM in aqueous solutions under ultraviolet light (λ = 365 nm) in the presence of a photoinitiator. The PFS-PILs serve as a macro-cross-linker and also provide redox responsiveness. The swelling ratio, morphology, and lower critical solution temperature (LCST) of the hydrogels are studied as a function of the PNIPAM/PFS ratio. The value of the LCST is dependent on the choice of the counterion of the PIL and the PNIPAM/PFS ratio. The hydrogel is employed as a reducing environment for the in situ fabrication of gold nanoparticles (AuNPs), forming AuNP-hydrogel composites. The localized surface plasmon resonance peak of the as-synthesized Au nanoparticles inside the hydrogel could be tuned by altering the temperature. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Formation of hydrogels based on chitosan/alginate for the delivery of lysozyme and their antibacterial activity.

PubMed

Wu, Tiantian; Huang, Jiaqi; Jiang, Yangyang; Hu, Yaqin; Ye, Xingqian; Liu, Donghong; Chen, Jianchu

2018-02-01

Novel hydrogels based on chitosan/sodium alginate (CS-ALG) were prepared to deliver and protect lysozyme while eliminating food-borne microorganisms. These hydrogels were characterized according to the zeta potential, optical microscopy, scanning electron microscopy (SEM), UV-visible spectroscopy (UV-vis), fourier transform infrared (FT-IR), and small-angle X-ray scattering (SAXS). The results demonstrated that the resultant hydrogels were negatively charged and spherical in shape. In addition, the maximum swelling ratio was 45.66±7.62 for CS-ALG hydrogels loaded with lysozyme. The relative activity of the released lysozyme was 87.72±3.96%, indicating that CS-ALG hydrogels are promising matrices for enzyme loading and adsorption. Furthermore, a 100% bacterial clearance rate of CS/ALG loaded with lysozyme was observed to correspond to the superposition effect stimulated by CS and lysozyme, which improved the antibacterial activity against E. coli and S. aureus compared to CS/ALG, suggesting its potential use in the food industry as well as other applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and evaluation of functional alginate hydrogels based on click chemistry for drug delivery applications.

PubMed

García-Astrain, Clara; Avérous, Luc

2018-06-15

Environment-sensitive alginate-based hydrogels for drug delivery applications are receiving increasing attention. However, most work in this field involves traditional cross-linking strategies which led to hydrogels with poor long-term stability. Herein, a series of chemically cross-linked alginate hydrogels was synthesized via click chemistry using Diels-Alder reaction by reacting furan-modified alginate and bifunctional cross-linkers. Alginate was successfully functionalized with furfurylamine. Then, 3D architectures were synthesized with water-soluble bismaleimides. Different substitution degrees were achieved in order to study the effect of alginate modification and the cross-linking extent over the behaviour of the hydrogels. The ensuing hydrogels were analysed in terms of microstructure, swelling, structure modification and rheological behaviour. The materials response to external stimuli such as pH was also investigated, revealing a pulsatile behaviour in a large pH range (1-13) and a clear pH-dependent swelling. Finally, vanillin release studies were conducted to demonstrate the potential of these biobased materials for drug delivery applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Gamma ray-induced synthesis of hyaluronic acid/chondroitin sulfate-based hydrogels for biomedical applications

NASA Astrophysics Data System (ADS)

Zhao, Linlin; Gwon, Hui-Jeong; Lim, Youn-Mook; Nho, Young-Chang; Kim, So Yeon

2015-01-01

Hyaluronic acid (HA)/chondroitin sulfate (CS)/poly(acrylic acid) (PAAc) hydrogel systems were synthesized by gamma-ray irradiation without the use of additional initiators or crosslinking agents to achieve a biocompatible hydrogel system for skin tissue engineering. HA and CS derivatives with polymerizable residues were synthesized. Then, the hydrogels composed of glycosaminoglycans, HA, CS, and a synthetic ionic polymer, PAAc, were prepared using gamma-ray irradiation through simultaneous free radical copolymerization and crosslinking. The physicochemical properties of the HA/CS/PAAc hydrogels having various compositions were investigated to evaluate their feasibility as artificial skin substitutes. The gel fractions of the HA/CS/PAAc hydrogels increased in absorbed doses up to 15 kGy, and they exhibited 91-93% gel fractions under 15 kGy radiation. All of the HA/CS/PAAc hydrogels exhibited relatively high water contents of over 90% and reached an equilibrium swelling state within 24 h. The enzymatic degradation kinetics of the HA/CS/PAAc hydrogels depended on both the concentration of the hyaluronidase solution and the ratio of HA/CS/PAAc. The in vitro drug release profiles of the HA/CS/PAAc hydrogels were significantly influenced by the interaction between the ionic groups in the hydrogels and the ionic drug molecules as well as the swelling of the hydrogels. From the cytotoxicity results of human keratinocyte (HaCaT) cells cultured with extracts of the HA/CS/PAAc hydrogels, all of the HA/CS/PAAc hydrogel samples tested showed relatively high cell viabilities of more than 82%, and did not induce any significant adverse effects on cell viability.

Encoding Hydrogel Mechanics via Network Cross-Linking Structure.

PubMed

Schweller, Ryan M; West, Jennifer L

2015-05-11

The effects of mechanical cues on cell behaviors in 3D remain difficult to characterize as the ability to tune hydrogel mechanics often requires changes in the polymer density, potentially altering the material's biochemical and physical characteristics. Additionally, with most PEG diacrylate (PEGDA) hydrogels, forming materials with compressive moduli less than ∼10 kPa has been virtually impossible. Here, we present a new method of controlling the mechanical properties of PEGDA hydrogels independent of polymer chain density through the incorporation of additional vinyl group moieties that interfere with the cross-linking of the network. This modification can tune hydrogel mechanics in a concentration dependent manner from <1 to 17 kPa, a more physiologically relevant range than previously possible with PEG-based hydrogels, without altering the hydrogel's degradation and permeability. Across this range of mechanical properties, endothelial cells (ECs) encapsulated within MMP-2/MMP-9 degradable hydrogels with RGDS adhesive peptides revealed increased cell spreading as hydrogel stiffness decreased in contrast to behavior typically observed for cells on 2D surfaces. EC-pericyte cocultures exhibited vessel-like networks within 3 days in highly compliant hydrogels as compared to a week in stiffer hydrogels. These vessel networks persisted for at least 4 weeks and deposited laminin and collagen IV perivascularly. These results indicate that EC morphogenesis can be regulated using mechanical cues in 3D. Furthermore, controlling hydrogel compliance independent of density allows for the attainment of highly compliant mechanical regimes in materials that can act as customizable cell microenvironments.

Bioactive gyroid scaffolds formed by sacrificial templating of nanocellulose and nanochitin hydrogels as instructive platforms for biomimetic tissue engineering.

PubMed

Torres-Rendon, Jose Guillermo; Femmer, Tim; De Laporte, Laura; Tigges, Thomas; Rahimi, Khosrow; Gremse, Felix; Zafarnia, Sara; Lederle, Wiltrud; Ifuku, Shinsuke; Wessling, Matthias; Hardy, John G; Walther, Andreas

2015-05-20

A sacrificial templating process using lithographically printed minimal surface structures allows complex de novo geo-metries of delicate hydrogel materials. The hydrogel scaffolds based on cellulose and chitin nanofibrils show differences in terms of attachment of human mesenchymal stem cells, and allow their differentiation into osteogenic outcomes. The approach here serves as a first example toward designer hydrogel scaffolds viable for biomimetic tissue engineering. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanostructured PEG-based hydrogels with tunable physical properties for gene delivery to human mesenchymal stem cells.

PubMed

Li, Yan; Yang, Chuan; Khan, Majad; Liu, Shaoqiong; Hedrick, James L; Yang, Yi-Yan; Ee, Pui-Lai R

2012-09-01

Effective delivery of DNA to direct cell behavior in a well defined three dimensional scaffold offers a superior approach in tissue engineering. In this study, we synthesized biodegradable nanostructured hydrogels with tunable physical properties for cell and gene delivery. The hydrogels were formed via Michael addition chemistry by reacting a four-arm acrylate-terminated PEG with a four-arm thiol-functionalized PEG. Nanosized micelles self-assembled from the amphiphilic PEG-b-polycarbonate diblock copolymer, having reactive end-groups, were chemically incorporated into the hydrogel networks at various contents. The use of Michael addition chemistry allows for in situ hydrogel formation under the physiological conditions. Mechanical property analysis of the hydrogels revealed a correlation between the content of micelles and the storage modulus of the hydrogels. Internal morphology of hydrogels was observed using a field emission scanning electron microscope, which showed that the number and/or size of the pores in the hydrogel increased with increasing micelle content due to reduced crosslinking degree. There exists an optimal micelle content for cell proliferation and gene transfection. MTT assays demonstrated the highest cell viability in the hydrogel with 20% micelles. The gene expression level in hMSCs in the hydrogel with 20% micelles was also significantly higher than that in the hydrogel without micelles. The enhanced cell viability and gene expression in the hydrogel with the optimized micelle content are likely attributed to the physical properties that provide a better environment for cell-matrix interactions. Therefore, incorporating micelles into the hydrogel is a good strategy to control cellular behavior in 3-D through changes in physical properties of the microenvironment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Applying macromolecular crowding to 3D bioprinting: fabrication of 3D hierarchical porous collagen-based hydrogel constructs.

PubMed

Ng, Wei Long; Goh, Min Hao; Yeong, Wai Yee; Naing, May Win

2018-02-27

Native tissues and/or organs possess complex hierarchical porous structures that confer highly-specific cellular functions. Despite advances in fabrication processes, it is still very challenging to emulate the hierarchical porous collagen architecture found in most native tissues. Hence, the ability to recreate such hierarchical porous structures would result in biomimetic tissue-engineered constructs. Here, a single-step drop-on-demand (DOD) bioprinting strategy is proposed to fabricate hierarchical porous collagen-based hydrogels. Printable macromolecule-based bio-inks (polyvinylpyrrolidone, PVP) have been developed and printed in a DOD manner to manipulate the porosity within the multi-layered collagen-based hydrogels by altering the collagen fibrillogenesis process. The experimental results have indicated that hierarchical porous collagen structures could be achieved by controlling the number of macromolecule-based bio-ink droplets printed on each printed collagen layer. This facile single-step bioprinting process could be useful for the structural design of collagen-based hydrogels for various tissue engineering applications.

Metallization of DNA hydrogel: application of soft matter host for preparation and nesting of catalytic nanoparticles

NASA Astrophysics Data System (ADS)

Zinchenko, Anatoly; Che, Yuxin; Taniguchi, Shota; Lopatina, Larisa I.; G. Sergeyev, Vladimir; Murata, Shizuaki

2016-07-01

Nanoparticles (NPs) of Au, Ag, Pt, Pd, Cu and Ni of 2-3 nm average-size and narrow-size distributions were synthesized in DNA cross-linked hydrogels by reducing corresponding metal precursors by sodium borohydride. DNA hydrogel plays a role of a universal reactor in which the reduction of metal precursor results in the formation of 2-3 nm ultrafine metal NPs regardless of metal used. Hydrogels metallized with various metals showed catalytic activity in the reduction of nitroaromatic compounds, and the catalytic activity of metallized hydrogels changed as follows: Pd > Ag ≈ Au ≈ Cu > Ni > Pt. DNA hydrogel-based "soft catalysts" elaborated in this study are promising for green organic synthesis in aqueous media as well as for biomedical in vivo applications.

Sequentially-crosslinked biomimetic bioactive glass/gelatin methacryloyl composites hydrogels for bone regeneration.

PubMed

Zheng, Jiafu; Zhao, Fujian; Zhang, Wen; Mo, Yunfei; Zeng, Lei; Li, Xian; Chen, Xiaofeng

2018-08-01

In recent years, gelatin-based composites hydrogels have been intensively investigated because of their inherent bioactivity, biocompatibility and biodegradability. Herein, we fabricated photocrosslinkable biomimetic composites hydrogels from bioactive glass (BG) and gelatin methacryloyl (GelMA) by a sequential physical and chemical crosslinking (gelation + UV) approach. The results showed that the compressive modulus of composites hydrogels increased significantly through the sequential crosslinking approach. The addition of BG resulted in a significant increase in physiological stability and apatite-forming ability. In vitro data indicated that BG/GelMA composites hydrogels promoted cell attachment, proliferation and differentiation. Overall, the BG/GelMA composites hydrogels combined the advantages of good biocompatibility and bioactivity, and had potential applications in bone regeneration. Copyright © 2018. Published by Elsevier B.V.

Light-triggered methylcellulose gold nanoparticle hydrogels for leptin release to inhibit fat stores in adipocytes.

PubMed

Liao, Zi-Xian; Liu, Meng-Chia; Kempson, Ivan M; Fa, Yu-Chen; Huang, Kuo-Yen

2017-01-01

Leptin is released in response to increased triglyceride storage in adipocytes and impacts body weight, but has drawbacks such as poor therapeutic effect and side effects when delivered systemically. Leptin also modifies adipocyte sensitivity to insulin to inhibit lipid accumulation. Here, light-triggered degradation of hydrogels was used to improve accuracy and effectiveness for sustained and controllable release. In our approach, leptin was entrapped within methylcellulose (MC)-based hydrogels, with incorporation of gold nanoparticles (NP). The incorporation of gold NP into MC hydrogels led to a tunable light irradiation response that dictated the hydrogel release rate of leptin. This manuscript demonstrates feasibility in designing tunable thermosensitive hydrogels for loading multimodality therapeutic agents to enhance the bioactivity of leptin for obesity therapy.

Carbon Nanotubes Reinforced Maleic Anhydride-Modified Xylan-g-Poly(N-isopropylacrylamide) Hydrogel with Multifunctional Properties

PubMed Central

Liu, Xinxin; Song, Tao; Chang, Minmin; Meng, Ling; Wang, Xiaohui; Sun, Runcang; Ren, Junli

2018-01-01

Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified xylan grafted with poly(N-isopropylacrylamide) (MAX-g-PNIPAM) hydrogels network. It was found that the addition of AT-CNTs affected the MAX-g-PNIPAM hydrogel structure, the swelling ratio and mechanical properties, and imparted the hydrogel with new properties of electrical conductivity and near infrared region (NIR) photothermal conversion. AT-CNTs could reinforce the mechanical properties of MAX-g-PNIPAM hydrogels, being up to 83 kPa for the compressive strength when the amount was 11 wt %, which was eight times than that of PNIPAM hydrogel and four times than that of MAX-g-PNIPAM hydrogel. The electroconductibility was enhanced by the increase of AT-CNTs amounts. Meanwhile, the composite hydrogel also exhibited multiple shape memory and NIR photothermal conversion properties, and water temperature was increased from 26 °C to 56 °C within 8 min under the NIR irradiation. Thus, the AT-CNTs reinforced MAX-g-PNIPAM hydrogel possessed promising multifunctional properties, which offered many potential applications in the fields of biosensors, thermal-arrest technology, and drug-controlled release. PMID:29495611

Carbon Nanotubes Reinforced Maleic Anhydride-Modified Xylan-g-Poly(N-isopropylacrylamide) Hydrogel with Multifunctional Properties.

PubMed

Liu, Xinxin; Song, Tao; Chang, Minmin; Meng, Ling; Wang, Xiaohui; Sun, Runcang; Ren, Junli

2018-02-28

Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified xylan grafted with poly(N-isopropylacrylamide) (MAX-g-PNIPAM) hydrogels network. It was found that the addition of AT-CNTs affected the MAX-g-PNIPAM hydrogel structure, the swelling ratio and mechanical properties, and imparted the hydrogel with new properties of electrical conductivity and near infrared region (NIR) photothermal conversion. AT-CNTs could reinforce the mechanical properties of MAX-g-PNIPAM hydrogels, being up to 83 kPa for the compressive strength when the amount was 11 wt %, which was eight times than that of PNIPAM hydrogel and four times than that of MAX-g-PNIPAM hydrogel. The electroconductibility was enhanced by the increase of AT-CNTs amounts. Meanwhile, the composite hydrogel also exhibited multiple shape memory and NIR photothermal conversion properties, and water temperature was increased from 26 °C to 56 °C within 8 min under the NIR irradiation. Thus, the AT-CNTs reinforced MAX-g-PNIPAM hydrogel possessed promising multifunctional properties, which offered many potential applications in the fields of biosensors, thermal-arrest technology, and drug-controlled release.

Crosslinked hydrogels-a promising class of insoluble solid molecular dispersion carriers for enhancing the delivery of poorly soluble drugs.

PubMed

Sun, Dajun D; Lee, Ping I

2014-02-01

Water-insoluble materials containing amorphous solid dispersions (ASD) are an emerging category of drug carriers which can effectively improve dissolution kinetics and kinetic solubility of poorly soluble drugs. ASDs based on water-insoluble crosslinked hydrogels have unique features in contrast to those based on conventional water-soluble and water-insoluble carriers. For example, solid molecular dispersions of poorly soluble drugs in poly(2-hydroxyethyl methacrylate) (PHEMA) can maintain a high level of supersaturation over a prolonged period of time via a feedback-controlled diffusion mechanism thus avoiding the initial surge of supersaturation followed by a sharp decline in drug concentration typically encountered with ASDs based on water-soluble polymers. The creation of both immediate- and controlled-release ASD dosage forms is also achievable with the PHEMA based hydrogels. So far, ASD systems based on glassy PHEMA have been shown to be very effective in retarding precipitation of amorphous drugs in the solid state to achieve a robust physical stability. This review summarizes recent research efforts in investigating the potential of developing crosslinked PHEMA hydrogels as a promising alternative to conventional water-soluble ASD carriers, and a related finding that the rate of supersaturation generation does affect the kinetic solubility profiles implications to hydrogel based ASDs.

Accelerated Leach Testing of Glass (ALTGLASS): II. Mineralization of hydrogels by leachate strong bases

DOE PAGES

Jantzen, Carol M.; Trivelpiece, Cory L.; Crawford, Charles L.; ...

2017-02-18

The durability of high level nuclear waste glasses must be predicted on geological time scales. Waste glass surfaces form hydrogels when in contact with water for varying test durations. As the glass hydrogels age, some exhibit an undesirable resumption of dissolution at long times while others exhibit near steady-state dissolution, that is, nonresumption of dissolution. Resumption of dissolution is associated with the formation of zeolitic phases while nonresumption of dissolution is associated with the formation of clay minerals. Hydrogels with a stoichiometry close to that of imogolite, (Al 2O 3·Si(OH) 4), with ferrihydrite (Fe 2O 3·0.5H 2O), have been shownmore » to be associated with waste glasses that resume dissolution. Aluminosilicate hydrogels with a stoichiometry of allophane-hisingerite ((Al,Fe) 2O 3·1.3-2Si(OH) 4) have been shown to be associated with waste glasses that exhibit near steady-state dissolution at long times. These phases are all amorphous and poorly crystalline and are also found on natural weathered basalt glasses. Interaction of these hydrogels with excess alkali and OH – (strong base) in the leachates, causes the Al 2O 3· nSiO 2 (where n=1-2) hydrogels to mineralize to zeolites. Excess alkali in the leachate is generated by alkali in the glass. As a result, preliminary rate-determining leach layer forming exchange reactions are hypothesized based on these findings.« less

Elastin-like Protein-Hyaluronic acid (ELP-HA) Hydrogels with Decoupled Mechanical and Biochemical cues for Cartilage Regeneration

PubMed Central

Zhu, Danqing; Wang, Huiyuan; Trinh, Pavin; Heilshorn, Sarah C.; Yang, Fan

2018-01-01

Hyaluronic acid (HA) is a major component of cartilage extracellular matrix and is an attractive material for use as 3D injectable matrices for cartilage regeneration. While previous studies have shown the promise of HA-based hydrogels to support cell-based cartilage formation, varying HA concentration generally led to simultaneous changes in both biochemical cues and stiffness. How cells respond to the change of biochemical content of HA remains largely unknown. Here we report an adaptable elastin-like protein-hyaluronic acid (ELP-HA) hydrogel platform using dynamic covalent chemistry, which allows varyiation of HA concentration without affecting matrix stiffness. ELP-HA hydrogels were created through dynamic hydrazone bonds via the reaction between hydrazine-modified ELP (ELP-HYD) and aldehyde-modified HA (HA-ALD). By tuning the stoichiometric ratio of aldehyde groups to hydrazine groups while maintaining ELP-HYD concentration constant, hydrogels with variable HA concentration (1.5%, 3%, or 5%) (w/v) were fabricated with comparable stiffness. To evaluate the effects of HA concentration on cell-based cartilage regeneration, chondrocytes were encapsulated within ELP-HA hydrogels with varying HA concentration. Increasing HA concentration led to a dose-dependent increase in cartilage-marker gene expression and enhanced sGAG deposition while minimizing undesirable fibrocartilage phenotype. The use of adaptable protein hydrogels formed via dynamic covalent chemistry may be broadly applicable as 3D scaffolds with decoupled niche properties to guide other desirable cell fates and tissue repair. PMID:28268018

Elastin-like protein-hyaluronic acid (ELP-HA) hydrogels with decoupled mechanical and biochemical cues for cartilage regeneration.

PubMed

Zhu, Danqing; Wang, Huiyuan; Trinh, Pavin; Heilshorn, Sarah C; Yang, Fan

2017-05-01

Hyaluronic acid (HA) is a major component of cartilage extracellular matrix and is an attractive material for use as 3D injectable matrices for cartilage regeneration. While previous studies have shown the promise of HA-based hydrogels to support cell-based cartilage formation, varying HA concentration generally led to simultaneous changes in both biochemical cues and stiffness. How cells respond to the change of biochemical content of HA remains largely unknown. Here we report an adaptable elastin-like protein-hyaluronic acid (ELP-HA) hydrogel platform using dynamic covalent chemistry, which allows variation of HA concentration without affecting matrix stiffness. ELP-HA hydrogels were created through dynamic hydrazone bonds via the reaction between hydrazine-modified ELP (ELP-HYD) and aldehyde-modified HA (HA-ALD). By tuning the stoichiometric ratio of aldehyde groups to hydrazine groups while maintaining ELP-HYD concentration constant, hydrogels with variable HA concentration (1.5%, 3%, or 5%) (w/v) were fabricated with comparable stiffness. To evaluate the effects of HA concentration on cell-based cartilage regeneration, chondrocytes were encapsulated within ELP-HA hydrogels with varying HA concentration. Increasing HA concentration led to a dose-dependent increase in cartilage-marker gene expression and enhanced sGAG deposition while minimizing undesirable fibrocartilage phenotype. The use of adaptable protein hydrogels formed via dynamic covalent chemistry may be broadly applicable as 3D scaffolds with decoupled niche properties to guide other desirable cell fates and tissue repair. Copyright © 2017 Elsevier Ltd. All rights reserved.

Accelerated Leach Testing of Glass (ALTGLASS): II. Mineralization of hydrogels by leachate strong bases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, Carol M.; Trivelpiece, Cory L.; Crawford, Charles L.

The durability of high level nuclear waste glasses must be predicted on geological time scales. Waste glass surfaces form hydrogels when in contact with water for varying test durations. As the glass hydrogels age, some exhibit an undesirable resumption of dissolution at long times while others exhibit near steady-state dissolution, that is, nonresumption of dissolution. Resumption of dissolution is associated with the formation of zeolitic phases while nonresumption of dissolution is associated with the formation of clay minerals. Hydrogels with a stoichiometry close to that of imogolite, (Al 2O 3·Si(OH) 4), with ferrihydrite (Fe 2O 3·0.5H 2O), have been shownmore » to be associated with waste glasses that resume dissolution. Aluminosilicate hydrogels with a stoichiometry of allophane-hisingerite ((Al,Fe) 2O 3·1.3-2Si(OH) 4) have been shown to be associated with waste glasses that exhibit near steady-state dissolution at long times. These phases are all amorphous and poorly crystalline and are also found on natural weathered basalt glasses. Interaction of these hydrogels with excess alkali and OH – (strong base) in the leachates, causes the Al 2O 3· nSiO 2 (where n=1-2) hydrogels to mineralize to zeolites. Excess alkali in the leachate is generated by alkali in the glass. As a result, preliminary rate-determining leach layer forming exchange reactions are hypothesized based on these findings.« less

Induction of neurite outgrowth in 3D hydrogel-based environments.

PubMed

Assunção-Silva, Rita C; Oliveira, Cátia Costa; Ziv-Polat, Ofra; Gomes, Eduardo D; Sahar, Abraham; Sousa, Nuno; Silva, Nuno A; Salgado, António J

2015-10-20

The ability of peripheral nervous system (PNS) axons to regenerate and re-innervate their targets after an injury has been widely recognized. However, despite the considerable advances made in microsurgical techniques, complete functional recovery is rarely achieved, especially for severe peripheral nerve injuries (PNIs). Therefore, alternative therapies that can successfully repair peripheral nerves are still essential. In recent years the use of biodegradable hydrogels enriched with growth-supporting and guidance cues, cell transplantation, and biomolecular therapies have been explored for the treatment of PNIs. Bearing this in mind, the aim of this study was to assess whether Gly-Arg-Gly-Asp-Ser synthetic peptide (GRGDS)-modified gellan gum (GG) based hydrogels could foster an amenable environment for neurite/axonal growth. Additionally, strategies to further improve the rate of neurite outgrowth were also tested, namely the use of adipose tissue derived stem cells (ASCs), as well as the glial derived neurotrophic factor (GDNF). In order to increase its stability and enhance its bioactivity, the GDNF was conjugated covalently to iron oxide nanoparticles (IONPs). The impact of hydrogel modification as well as the effect of the GDNF-IONPs on ASC behavior was also screened. The results revealed that the GRGDS-GG hydrogel was able to support dorsal root ganglia (DRG)-based neurite outgrowth, which was not observed for non-modified hydrogels. Moreover, the modified hydrogels were also able to support ASCs attachment. In contrast, the presence of the GDNF-IONPs had no positive or negative impact on ASC behavior. Further experiments revealed that the presence of ASCs in the hydrogel improved axonal growth. On the other hand, GDNF-IONPs alone or combined with ASCs significantly increased neurite outgrowth from DRGs, suggesting a beneficial role of the proposed strategy for future applications in PNI regenerative medicine.

Myocardial matrix-polyethylene glycol hybrid hydrogels for tissue engineering

NASA Astrophysics Data System (ADS)

Grover, Gregory N.; Rao, Nikhil; Christman, Karen L.

2014-01-01

Similar to other protein-based hydrogels, extracellular matrix (ECM) based hydrogels, derived from decellularized tissues, have a narrow range of mechanical properties and are rapidly degraded. These hydrogels contain natural cellular adhesion sites, form nanofibrous networks similar to native ECM, and are biodegradable. In this study, we expand the properties of these types of materials by incorporating poly(ethylene glycol) (PEG) into the ECM network. We use decellularized myocardial matrix as an example of a tissue specific ECM derived hydrogel. Myocardial matrix-PEG hybrids were synthesized by two different methods, cross-linking the proteins with an amine-reactive PEG-star and photo-induced radical polymerization of two different multi-armed PEG-acrylates. We show that both methods allow for conjugation of PEG to the myocardial matrix by gel electrophoresis and infrared spectroscopy. Scanning electron microscopy demonstrated that the hybrid materials still contain a nanofibrous network similar to unmodified myocardial matrix and that the fiber diameter is changed by the method of PEG incorporation and PEG molecular weight. PEG conjugation also decreased the rate of enzymatic degradation in vitro, and increased material stiffness. Hybrids synthesized with amine-reactive PEG had gelation rates of 30 min, similar to the unmodified myocardial matrix, and incorporation of PEG did not prevent cell adhesion and migration through the hydrogels, thus offering the possibility to have an injectable ECM hydrogel that degrades more slowly in vivo. The photo-polymerized radical systems gelled in 4 min upon irradiation, allowing 3D encapsulation and culture of cells, unlike the soft unmodified myocardial matrix. This work demonstrates that PEG incorporation into ECM-based hydrogels can expand material properties, thereby opening up new possibilities for in vitro and in vivo applications.

Hyaluronic Acid and Polyethylene Glycol Hybrid Hydrogel Encapsulating Nanogel with Hemostasis and Sustainable Antibacterial Property for Wound Healing.

PubMed

Zhu, Jie; Li, Faxue; Wang, Xueli; Yu, Jianyong; Wu, Dequn

2018-04-25

Immediate hemorrhage control and anti-infection play important roles in the wound management. Besides, a moist environment is also beneficial for wound healing. Hydrogels are promising materials in urgent hemostasis and drug release. However, hydrogels have the disadvantage of rapid release profiles, leading to the exposure to high drug concentrations. In this study, we constructed hybrid hydrogels with rapid hemostasis and sustainable antibacterial property combining aminoethyl methacrylate hyaluronic acid (HA-AEMA) and methacrylated methoxy polyethylene glycol (mPEG-MA) hybrid hydrogels and chlorhexidine diacetate (CHX)-loaded nanogels. The CHX-loaded nanogels (CLNs) were prepared by the enzyme degradation of CHX-loaded lysine-based hydrogels. The HA-AEMA and mPEG-MA hybrid hydrogel loaded with CLNs (labeled as Gel@CLN) displayed a three-dimensional microporous structure and exhibited excellent swelling, mechanical property, and low cytotoxicity. The Gel@CLN hydrogel showed a prolonged release period of CHX over 240 h and the antibacterial property over 10 days. The hemostasis and wound-healing properties were evaluated in vivo using a mouse model. The results showed that hydrogel had the rapid hemostasis capacity and accelerated wound healing. In summary, CLN-loaded hydrogels may be excellent candidates as hemostasis and anti-infection materials for the wound dressing application.

Preparation of the chitosan/poly(glutamic acid)/alginate polyelectrolyte complexing hydrogel and study on its drug releasing property.

PubMed

Chen, Yu; Yan, Xiaoting; Zhao, Jian; Feng, Huaiyu; Li, Puwang; Tong, Zongrui; Yang, Ziming; Li, Sidong; Yang, Jueying; Jin, Shaohua

2018-07-01

In the current study, a novel semi-dissolution/acidification/sol-gel transition (SD-A-SGT) method was explored for the preparation of polyelectrolyte complexing (PEC) composite hydrogels with natural polymers only. A chitosan (CS) powder was uniformly dispersed in a solution of poly(glutamic acid) (PGA) and alginate (SA) to form a semi-dissolved slurry mixture that was then exposed to an gaseous acidic atmosphere. CS was gradually dissolved and interacted with PGA and SA to form a CS/PGA/SA PEC composite hydrogel with a homogeneous structure. The SD-A-SGT procedure was able to overcome the shortcomings of direct mixing method via the PEC interaction. The effects of the hydrogel composition on its structure and properties were investigated by FTIR, XRD, rheology study, XPS, SEM, and swelling kinetics. The drug delivery performance of the CS/PGA/SA hydrogel was explored using piroxicam (PXC) as a model drug. PXC was in situ embedded in the hydrogel by the SD-A-SGT method. The hydrogel exhibited pH responsive drug release behaviors that were affected by the hydrogel composition. In all, the SD-A-SGT method for preparing PEC composite hydrogels has a great application potential in constructing the CS based hydrogels as medical materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Controlling mechanical properties of cell-laden hydrogels by covalent incorporation of graphene oxide.

PubMed

Cha, Chaenyung; Shin, Su Ryon; Gao, Xiguang; Annabi, Nasim; Dokmeci, Mehmet R; Tang, Xiaowu Shirley; Khademhosseini, Ali

2014-02-12

Graphene-based materials are useful reinforcing agents to modify the mechanical properties of hydrogels. Here, an approach is presented to covalently incorporate graphene oxide (GO) into hydrogels via radical copolymerization to enhance the dispersion and conjugation of GO sheets within the hydrogels. GO is chemically modified to present surface-grafted methacrylate groups (MeGO). In comparison to GO, higher concentrations of MeGO can be stably dispersed in a pre-gel solution containing methacrylated gelatin (GelMA) without aggregation or significant increase in viscosity. In addition, the resulting MeGO-GelMA hydrogels demonstrate a significant increase in fracture strength with increasing MeGO concentration. Interestingly, the rigidity of the hydrogels is not significantly affected by the covalently incorporated GO. Therefore, this approach can be used to enhance the structural integrity and resistance to fracture of the hydrogels without inadvertently affecting their rigidity, which is known to affect the behavior of encapsulated cells. The biocompatibility of MeGO-GelMA hydrogels is confirmed by measuring the viability and proliferation of the encapsulated fibroblasts. Overall, this study highlights the advantage of covalently incorporating GO into a hydrogel system, and improves the quality of cell-laden hydrogels. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tumor Growth Suppression Induced by Biomimetic Silk Fibroin Hydrogels

NASA Astrophysics Data System (ADS)

Yan, Le-Ping; Silva-Correia, Joana; Ribeiro, Viviana P.; Miranda-Gonçalves, Vera; Correia, Cristina; da Silva Morais, Alain; Sousa, Rui A.; Reis, Rui M.; Oliveira, Ana L.; Oliveira, Joaquim M.; Reis, Rui L.

2016-08-01

Protein-based hydrogels with distinct conformations which enable encapsulation or differentiation of cells are of great interest in 3D cancer research models. Conformational changes may cause macroscopic shifts in the hydrogels, allowing for its use as biosensors and drug carriers. In depth knowledge on how 3D conformational changes in proteins may affect cell fate and tumor formation is required. Thus, this study reports an enzymatically crosslinked silk fibroin (SF) hydrogel system that can undergo intrinsic conformation changes from random coil to β-sheet conformation. In random coil status, the SF hydrogels are transparent, elastic, and present ionic strength and pH stimuli-responses. The random coil hydrogels become β-sheet conformation after 10 days in vitro incubation and 14 days in vivo subcutaneous implantation in rat. When encapsulated with ATDC-5 cells, the random coil SF hydrogel promotes cell survival up to 7 days, whereas the subsequent β-sheet transition induces cell apoptosis in vitro. HeLa cells are further incorporated in SF hydrogels and the constructs are investigated in vitro and in an in vivo chick chorioallantoic membrane model for tumor formation. In vivo, Angiogenesis and tumor formation are suppressed in SF hydrogels. Therefore, these hydrogels provide new insights for cancer research and uses of biomaterials.

Poly(amido-amine)-based hydrogels with tailored mechanical properties and degradation rates for tissue engineering.

PubMed

Martello, Federico; Tocchio, Alessandro; Tamplenizza, Margherita; Gerges, Irini; Pistis, Valentina; Recenti, Rossella; Bortolin, Monica; Del Fabbro, Massimo; Argentiere, Simona; Milani, Paolo; Lenardi, Cristina

2014-03-01

Poly(amido-amine) (PAA) hydrogels containing the 2,2-bisacrylamidoacetic acid-4-amminobutyl guanidine monomeric unit have a known ability to enhance cellular adhesion by interacting with the arginin-glycin-aspartic acid (RGD)-binding αVβ3 integrin, expressed by a wide number of cell types. Scientific interest in this class of materials has traditionally been hampered by their poor mechanical properties and restricted range of degradation rate. Here we present the design of novel biocompatible, RGD-mimic PAA-based hydrogels with wide and tunable degradation rates as well as improved mechanical and biological properties for biomedical applications. This is achieved by radical polymerization of acrylamide-terminated PAA oligomers in both the presence and absence of 2-hydroxyethylmethacrylate. The degradation rate is found to be precisely tunable by adjusting the PAA oligomer molecular weight and acrylic co-monomer concentration in the starting reaction mixture. Cell adhesion and proliferation tests on Madin-Darby canine kidney epithelial cells show that PAA-based hydrogels have the capacity to promote cell adhesion up to 200% compared to the control. Mechanical tests show higher compressive strength of acrylic chain containing hydrogels compared to traditional PAA hydrogels. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Wound healing applications of sericin/chitosan-capped silver nanoparticles incorporated hydrogel.

PubMed

Verma, Jyoti; Kanoujia, Jovita; Parashar, Poonam; Tripathi, Chandra Bhusan; Saraf, Shubhini A

2017-02-01

Microbial contamination in wounds leading to severe sepsis can be treated by silver-based antiseptics. However, frequent application of silver-based antiseptics, staining of skin, burning, and irritation at application site resulted to poor patient compliances. Thus, we formulated sericin- and chitosan-capped silver nanoparticle (S/C-SNP)-loaded hydrogel for accelerated wound healing and antimicrobial properties. The wound healing property of sericin, antibacterial nature of chitosan and silver, and mucoadhesive property of carbopol were utilized in development of novel wound dressing hydrogel to investigate the combined effect of these materials for effective treatment of wounds. The chemical reduction method was successfully employed for the synthesis of SNPs using sericin and chitosan as a capping/reducing agent. The SNPs were characterized by ultraviolet-spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The optimized SNPs were further used for preparation of carbopol hydrogel (0.5, 0.75, and 1.0 % w/v). The prepared hydrogels were characterized for pH, viscosity, and texture analysis. The antimicrobial activity and wound healing activity of the optimized hydrogel (S/C-SNPs G-1) demonstrated higher bactericidal activity and wound closure, as supported by results of histopathology. Hydrogel containing capped SNPs has application in wound healing treatment.

Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels

PubMed Central

Yue, Kan; Santiago, Grissel Trujillo-de; Alvarez, Mario Moisés; Tamayol, Ali; Annabi, Nasim; Khademhosseini, Ali

2015-01-01

Gelatin methacryloyl (GelMA) hydrogels have been widely used for various biomedical applications due to their suitable biological properties and tunable physical characteristics. Three dimensional (3D) GelMA hydrogels closely resemble some essential properties of native extracellular matrix (ECM) due to the presence of cell-attaching and matrix metalloproteinase responsive peptide motifs, which allow cells to proliferate and spread in GelMA-based scaffolds. GelMA is also versatile from a processing perspective. It crosslinks when exposed to light irradiation to form hydrogels with tunable mechanical properties which mimic the native ECM. It can also be microfabricated using different methodologies including micromolding, photomasking, bioprinting, self-assembly, and microfluidic techniques to generate constructs with controlled architectures. Hybrid hydrogel systems can also be formed by mixing GelMA with nanoparticles such as carbon nanotubes and graphene oxide, and other polymers to form networks with desired combined properties and characteristics for specific biological applications. Recent research has demonstrated the proficiency of GelMA-based hydrogels in a wide range of applications including engineering of bone, cartilage, cardiac, and vascular tissues, among others. Other applications of GelMA hydrogels, besides tissue engineering, include fundamental single-single cell research, cell signaling, drug and gene delivery, and bio-sensing. PMID:26414409

Development of hydrogels for regenerative engineering.

PubMed

Guan, Xiaofei; Avci-Adali, Meltem; Alarçin, Emine; Cheng, Hao; Kashaf, Sara Saheb; Li, Yuxiao; Chawla, Aditya; Jang, Hae Lin; Khademhosseini, Ali

2017-05-01

The aim of regenerative engineering is to restore complex tissues and biological systems through convergence in the fields of advanced biomaterials, stem cell science, and developmental biology. Hydrogels are one of the most attractive biomaterials for regenerative engineering, since they can be engineered into tissue mimetic 3D scaffolds to support cell growth due to their similarity to native extracellular matrix. Advanced nano- and micro-technologies have dramatically increased the ability to control properties and functionalities of hydrogel materials by facilitating biomimetic fabrication of more sophisticated compositions and architectures, thus extending our understanding of cell-matrix interactions at the nanoscale. With this perspective, this review discusses the most commonly used hydrogel materials and their fabrication strategies for regenerative engineering. We highlight the physical, chemical, and functional modulation of hydrogels to design and engineer biomimetic tissues based on recent achievements in nano- and micro-technologies. In addition, current hydrogel-based regenerative engineering strategies for treating multiple tissues, such as musculoskeletal, nervous and cardiac tissue, are also covered in this review. The interaction of multiple disciplines including materials science, cell biology, and chemistry, will further play an important role in the design of functional hydrogels for the regeneration of complex tissues. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enzyme-Regulated Fast Self-Healing of a Pillararene-Based Hydrogel.

PubMed

Zhang, Xin; Xu, Jiayun; Lang, Chao; Qiao, Shanpeng; An, Guo; Fan, Xiaotong; Zhao, Linlu; Hou, Chunxi; Liu, Junqiu

2017-06-12

Self-healing, one of the exciting properties of materials, is frequently used to repair the damage of biological and artificial systems. Here we have used enzymatic catalysis approaches to develop a fast self-healing hydrogel, which has been constructed by dynamic aldimine cross-linking of pillar[5]arene-derivant and dialdehyde-functionalized PEG followed by encapsulation of glucose oxidase (GOx) and catalase (CAT). In specific, the two hydroxyl groups at terminal of PEG 4000 are functionalized with benzaldehydes that can interact with amino-containing pillar[5]arene-derivant through dynamic aldimine cross-links, resulting in reversible dynamic hydrogels. Modulus analysis indicated that storage modulus (G') and loss modulus (G″) of the hydrogel increased obviously as the concentration of dialdehyde-functionalized PEG 4000 (DF-PEG 4000 ) increased or the pH values decreased. Once glucose oxidase (GOx) and catalase (CAT) are located, the hydrogel could be fast repaired, with self-healing efficiency up to 100%. Notably tensile test showed that the repair process of pillararene-based hydrogel can finish in several minutes upon enzyme catalysis, while it needed more than 24 h to achieve this recovery without enzymes. This enzyme-regulated self-healing hydrogel would hold promise for delivering drugs and for soft tissue regeneration in the future.

Synthesis and characterization of arginine-NIPAAm hybrid hydrogel as wound dressing: In vitro and in vivo study.

PubMed

Wu, De-Qun; Zhu, Jie; Han, Hua; Zhang, Jun-Zhi; Wu, Fei-Fei; Qin, Xiao-Hong; Yu, Jian-Yong

2018-01-01

A multi-functional hybrid hydrogel P(M-Arg/NIPAAm) with temperature response, anti-protein adsorption and antibacterial properties was prepared and applied as wound dressing. The hydrogel was carried out by free radical copolymerization of methacrylate arginine (M-Arg) and N-isopropyl acrylamide (NIPAAm) monomers using N,N'-methylene bisacrylamide as a crosslinker, and ammonium persulfate/N,N,N', N'-tetramethylethylenediamine as the redox initiator. To endow the antimicrobial property, chlorhexidine diacetate (CHX) was preloaded into the hydrogel and polyhexamethylene guanidine phosphate (PHMG) was grafted on the hydrogel surface, respectively. The antimicrobial property of two series of hydrogels was evaluated and compared. The successful synthesis of M-Arg, PHMG and hydrogels was proved by 13 C NMR, 1 H NMR and FTIR spectroscopy. The hydrogel morphology characterized by scanning electron microscopy confirmed that the homogeneous porous and interconnected structures of the hydrogels. The swelling, protein adsorption property, in vitro release of CHX, antimicrobial assessment, cell viability as well as in vivo wound healing in a mouse model were studied. The results showed the nontoxicity and antimicrobial P(M-Arg/NIPAAm) hydrogel accelerated the full-thickness wound healing process and had the potential application in wound dressing. Despite the zwitterionic characteristic and biocompatible property of arginine based hydrogels, the brittle behavior and non-transparency still remain as a significant problem for wound dressing. Furthermore promoting the antibacterial property of the zwitterionic hydrogel is also necessary to prevent the bacterial colonization and subsequent wound infection. Therefore, we created a hybrid hydrogel combined methacrylate arginine (M-Arg) and N-isopropyl acrylamide (NIPAAm). NIPAAm improves transparency and mechanical property as well as acts as a temperature-response drug release system. Additionally, chlorhexidine (CHX) was preloaded into the hydrogels and polyhexamethylene guanidine phosphate (PHMG) was grafted on the hydrogel surface, respectively, which make the hydrogel useful as a favorable antibacterial dressing. The hybrid hydrogel has a combination effect of biocompatibility, environmentally responsive transformation behavior, biodegradability, anti-protein adsorption and antimicrobial properties. This report proposes the preparation of P(M-Arg/NIPAAm) hydrogel that has a great potential for wound healing. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of visible-light responsive and mechanically enhanced "smart" UCST interpenetrating network hydrogels.

PubMed

Xu, Yifei; Ghag, Onkar; Reimann, Morgan; Sitterle, Philip; Chatterjee, Prithwish; Nofen, Elizabeth; Yu, Hongyu; Jiang, Hanqing; Dai, Lenore L

2017-12-20

An interpenetrating polymer network (IPN), chlorophyllin-incorporated environmentally responsive hydrogel was synthesized and exhibited the following features: enhanced mechanical properties, upper critical solution temperature (UCST) swelling behavior, and promising visible-light responsiveness. Poor mechanical properties are known challenges for hydrogel-based materials. By forming an interpenetrating network between polyacrylamide (PAAm) and poly(acrylic acid) (PAAc) polymer networks, the mechanical properties of the synthesized IPN hydrogels were significantly improved compared to hydrogels made of a single network of each polymer. The formation of the interpenetrating network was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), the analysis of glass transition temperature, and a unique UCST responsive swelling behavior, which is in contrast to the more prevalent lower critical solution temperature (LCST) behaviour of environmentally responsive hydrogels. The visible-light responsiveness of the synthesized hydrogel also demonstrated a positive swelling behavior, and the effect of incorporating chlorophyllin as the chromophore unit was observed to reduce the average pore size and further enhance the mechanical properties of the hydrogel. This interpenetrating network system shows potential to serve as a new route in developing "smart" hydrogels using visible-light as a simple, inexpensive, and remotely controllable stimulus.

Subconjunctivally Implantable Hydrogels with Degradable and Thermoresponsive Properties for Sustained Release of Insulin to the Retina

PubMed Central

Misra, Gauri P.; Singh, Ravi S.J.; Aleman, Tomas S.; Jacobson, Samuel G.; Gardner, Thomas W.; Lowe, Tao L.

2009-01-01

The objective of this work is to develop subconjunctivally implantable, biodegradable hydrogels for sustained release of intact insulin to the retina to prevent and treat retinal neurovascular degeneration such as diabetic retinopathy. The hydrogels are synthesized by UV photopolymerization of N-isopropylacrylamide (NIPAAm) monomer and a dextran macromer containing multiple hydrolytically degradable oligolactate-(2-hydroxyetheyl methacrylate) units (Dex-lactateHEMA) in 25:75 (v:v) ethanol:water mixture solvent. Insulin is loaded into the hydrogels during the synthesis process with loading efficiency up to 98%. The hydrogels can release biologically active insulin in vitro for at least one week and the release kinetics can be modulated by varying the ratio between NIPAAm and Dex-lactateHEMA and altering the physical size of the hydrogels. The hydrogels are not toxic to R28 retinal neuron cells in culture medium with 100% cell viability. The hydrogels can be implanted under the conjunctiva without causing adverse effects to the retina based on hematoxylin and eosin stain, immunostaining for microglial cell activation, and electroretinography. These subconjunctivally implantable hydrogels have potential for long-term periocular delivery of insulin or other drugs to treat diabetic retinopathy and other retinal diseases. PMID:19709741

Heparin-based hydrogels with tunable sulfation & degradation for anti-inflammatory small molecule delivery.

PubMed

Peng, Yifeng; Tellier, Liane E; Temenoff, Johnna S

2016-08-16

Sustained release of anti-inflammatory agents remains challenging for small molecule drugs due to their low molecular weight and hydrophobicity. Therefore, the goal of this study was to control the release of a small molecule anti-inflammatory agent, crystal violet (CV), from hydrogels fabricated with heparin, a highly sulfated glycosaminoglycan capable of binding positively-charged molecules such as CV. In this system, both electrostatic interactions between heparin and CV and hydrogel degradation were tuned simultaneously by varying the level of heparin sulfation and varying the amount of dithiothreitol within hydrogels, respectively. It was found that heparin sulfation significantly affected CV release, whereby more sulfated heparin hydrogels (Hep and Hep(-N)) released CV with near zero-order release kinetics (R-squared values between 0.96-0.99). Furthermore, CV was released more quickly from fast-degrading hydrogels than slow-degrading hydrogels, providing a method to tune total CV release between 5-15 days while maintaining linear release kinetics. In particular, N-desulfated heparin hydrogels exhibited efficient CV loading (∼90% of originally included CV), near zero-order CV release kinetics, and maintenance of CV bioactivity after release, making this hydrogel formulation a promising CV delivery vehicle for a wide range of inflammatory diseases.

Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

NASA Astrophysics Data System (ADS)

Reddy, N. Narayana; Ravindra, S.; Reddy, N. Madhava; Rajinikanth, V.; Raju, K. Mohana; Vallabhapurapu, Vijaya Srinivasu

2015-11-01

The present work deals with the development of temperature and magnetic responsive hydrogel networks based on poly (N-isopropylacrylamide)/acrylamido propane sulfonic acid. The hydrogel matrices are synthesized by polymerizing N-isopropylacrylamide (NIPAM) monomer in the presence of acrylamido propane sulphonicacid (AMPS) using a cross-linker (N,N-methylenebisacrylamide, MBA) and redox initiating system [ammonium persulphate (APS)/tetramethylethylenediamine (TMEDA)]. The magnetic nanoparticles are generated throughout the hydrogel networks using in situ method by incorporating iron ions and subsequent treatment with ammonia. A series of hydrogel-magnetic nanocomposites (HGMNC) are developed by varying AMPS composition. The synthesized hydrogel magnetic nanocomposites (HGMNC) are characterized by using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Thermal Analyses and Electron Microscopy analysis (Scanning and Transmission Electron Microscope). The metal extraction capacities of the prepared hydrogel (HG) and hydrogel magnetic nanocomposites (HGMNC) were studied at different temperatures. The results suggest that HGMNCs have higher extraction capacity compared to HG and HG loaded iron ions. This data also reveals that the extraction of metals by hydrogel magnetic nanocomposites (HGMNCs) is higher at higher temperatures than room temperature. The prepared HGMNCs are also subjected to hyperthermia (cancer therapy) studies.

The Formation Mechanism of Hydrogels.

PubMed

Lu, Liyan; Yuan, Shiliang; Wang, Jing; Shen, Yun; Deng, Shuwen; Xie, Luyang; Yang, Qixiang

2017-06-12

Hydrogels are degradable polymeric networks, in which cross-links play a vital role in structure formation and degradation. Cross-linking is a stabilization process in polymer chemistry that leads to the multi-dimensional extension of polymeric chains, resulting in network structures. By cross-linking, hydrogels are formed into stable structures that differ from their raw materials. Generally, hydrogels can be prepared from either synthetic or natural polymers. Based on the types of cross-link junctions, hydrogels can be categorized into two groups: the chemically cross-linked and the physically cross-linked. Chemically cross-linked gels have permanent junctions, in which covalent bonds are present between different polymer chains, thus leading to excellent mechanical strength. Although chemical cross-linking is a highly resourceful method for the formation of hydrogels, the cross-linkers used in hydrogel preparation should be extracted from the hydrogels before use, due to their reported toxicity, while, in physically cross-linked gels, dissolution is prevented by physical interactions, such as ionic interactions, hydrogen bonds or hydrophobic interactions. Physically cross-linked methods for the preparation of hydrogels are the alternate solution for cross-linker toxicity. Both methods will be discussed in this essay. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Microcontact printing of polydopamine on thermally expandable hydrogels for controlled cell adhesion and delivery of geometrically defined microtissues.

PubMed

Lee, Yu Bin; Kim, Se-Jeong; Kim, Eum Mi; Byun, Hayeon; Chang, Hyung-Kwan; Park, Jungyul; Choi, Yu Suk; Shin, Heungsoo

2017-10-01

Scaffold-free harvest of microtissue with a defined structure has received a great deal of interest in cell-based assay and regenerative medicine. In this study, we developed thermally expandable hydrogels with spatially controlled cell adhesive patterns for rapid harvest of geometrically controlled microtissue. We patterned polydopamine (PD) on to the hydrogel via microcontact printing (μCP), in linear shapes with widths of 50, 100 and 200μm. The hydrogels facilitated formation of spatially controlled strip-like microtissue of human dermal fibroblasts (HDFBs). It was possible to harvest and translocate microtissues with controlled widths of 61.4±14.7, 104.3±15.6, and 186.6±22.3μm from the hydrogel to glass substrates by conformal contact upon expansion of the hydrogel in response to a temperature change from 37 to 4°C, preserving high viability, extracellular matrix, and junction proteins. Microtissues were readily translocated in vivo to the subcutaneous tissue of mouse. The microtissues were further utilized as a simple assay model for monitoring of contraction in response to ROCK1 inhibitor. Collectively, micro-sized patterning of PD on the thermally expandable hydrogels via μCP holds promise for the development of microtissue harvesting systems that can be employed to ex vivo tissue assay and cell-based therapy. Harvest of artificial tissue with controlled cellular arrangement independently from external materials has been widely studied in cell-based assay and regenerative medicine. In this study, we developed scaffold-free harvest system of microtissues with anisotropic arrangement and controlled width by exploiting thermally expandable hydrogels with cell-adhesive patterns of polydopamine formed by simple microcontact printing. Cultured strips of human dermal fibroblasts on the hydrogels were rapidly delivered to various targets ranging from flat coverglass to mice subcutaneous tissue by thermal expansion of the hydrogel at 4°C for 10min. These were further utilized as a drug screening model responding to ROCK1 inhibitor, which imply its versatile applicability. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Ciprofloxacin-lidocaine-based hydrogel: development, characterization, and in vivo evaluation in a second-degree burn model.

PubMed

Sanchez, María Florencia; Breda, Susana Andrea; Soria, Elio Andrés; Tártara, Luis Ignacio; Manzo, Rubén Hilario; Olivera, María Eugenia

2018-04-13

The purpose of this work was to develop an effective carbomer hydrogel to be used to treat second-degree burns that combined ciprofloxacin and lidocaine (CbCipLid hydrogel). Its antibiotic and anesthetic efficacy and the physical and chemical properties of the CbCipLid hydrogel (release rate and kinetics, rheology, appearance, and drug content) were evaluated both before and after a sterilization cycle and also after 6 months of storage. For the in vivo studies, second-degree burns were developed in a rat model. Animals were divided into three groups: CbCipLid hydrogel, silver sulfadiazine cream (reference), and carbomer hydrogel (as control). The treatments were applied daily for 21 days, and the healing was monitored by macroscopic observation and histologic evaluation. The anesthetic effect was evaluated through the corneal touch threshold in a rabbit eye model. The CbCipLid hydrogel obtained is transparent and allows the loading of ciprofloxacin above its solubility at a neutral pH, with a rheology which is convenient for topical administration. Its physical and chemical properties remained unchanged after sterilization and for at least six additional months. Both ciprofloxacin and lidocaine are reversibly released from the CbCipLid hydrogel with a kinetics fitting the Higuchi model. The presence of a biologic-like fluid increased the rate of drug delivery through an ionic exchange mechanism. Treatment with the CbCipLid hydrogel decreased the wound-healing period, compared with the reference, and was associated with a greater number of fibroblasts and a faster rate of epithelialization and dermis reconstruction. These differences were assigned to the moist environment provided by the hydrogel and also to the presence of a therapeutic concentration of ciprofloxacin. Moreover, CbCipLid hydrogel provides an immediate anesthetic effect, which is significantly more intense than that of the reference. Based on these results, it is believed that the CbCipLid hydrogel could be a potential candidate in the prophylaxis/treatment of second-degree burns.

Application of a Dense Gas Technique for Sterilizing Soft Biomaterials

PubMed Central

Karajanagi, Sandeep S.; Yoganathan, Roshan; Mammucari, Raffaella; Park, Hyoungshin; Cox, Julian; Zeitels, Steven M.; Langer, Robert; Foster, Neil R.

2017-01-01

Sterilization of soft biomaterials such as hydrogels is challenging because existing methods such as gamma irradiation, steam sterilization, or ethylene oxide sterilization, while effective at achieving high sterility assurance levels (SAL), may compromise their physicochemical properties and biocompatibility. New methods that effectively sterilize soft biomaterials without compromising their properties are therefore required. In this report, a dense-carbon dioxide (CO2)-based technique was used to sterilize soft polyethylene glycol (PEG)-based hydrogels while retaining their structure and physicochemical properties. Conventional sterilization methods such as gamma irradiation and steam sterilization severely compromised the structure of the hydrogels. PEG hydrogels with high water content and low elastic shear modulus (a measure of stiffness) were deliberately inoculated with bacteria and spores and then subjected to dense CO2. The dense CO2-based methods effectively sterilized the hydrogels achieving a SAL of 10−7 without compromising the viscoelastic properties, pH, water-content, and structure of the gels. Furthermore, dense CO2-treated gels were biocompatible and non-toxic when implanted subcutaneously in ferrets. The application of novel dense CO2-based methods to sterilize soft biomaterials has implications in developing safe sterilization methods for soft biomedical implants such as dermal fillers and viscosupplements. PMID:21337339

A photonic crystal hydrogel suspension array for the capture of blood cells from whole blood

NASA Astrophysics Data System (ADS)

Zhang, Bin; Cai, Yunlang; Shang, Luoran; Wang, Huan; Cheng, Yao; Rong, Fei; Gu, Zhongze; Zhao, Yuanjin

2016-02-01

Diagnosing hematological disorders based on the separation and detection of cells in the patient's blood is a significant challenge. We have developed a novel barcode particle-based suspension array that can simultaneously capture and detect multiple types of blood cells. The barcode particles are polyacrylamide (PAAm) hydrogel inverse opal microcarriers with characteristic reflection peak codes that remain stable during cell capture on their surfaces. The hydrophilic PAAm hydrogel scaffolds of the barcode particles can entrap various plasma proteins to capture different cells in the blood, with little damage to captured cells.Diagnosing hematological disorders based on the separation and detection of cells in the patient's blood is a significant challenge. We have developed a novel barcode particle-based suspension array that can simultaneously capture and detect multiple types of blood cells. The barcode particles are polyacrylamide (PAAm) hydrogel inverse opal microcarriers with characteristic reflection peak codes that remain stable during cell capture on their surfaces. The hydrophilic PAAm hydrogel scaffolds of the barcode particles can entrap various plasma proteins to capture different cells in the blood, with little damage to captured cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06368j

In situ gelable interpenetrating double network hydrogel formulated from binary components: thiolated chitosan and oxidized dextran.

PubMed

Zhang, Hanwei; Qadeer, Aisha; Chen, Weiliam

2011-05-09

In situ gelable interpenetrating double-network hydrogels composed of thiolated chitosan (Chitosan-NAC) and oxidized dextran (Odex), completely devoid of potentially cytotoxic small molecule cross-linkers and that do not require complex maneuvers or catalysis, have been formulated. The interpenetrating network structure is created by Schiff base formations and disulfide bond inter-cross-linkings through exploiting the disparity of their reaction times. Compared with the autogelable thiolated chitosan hydrogels that typically require a relatively long time span for gelation to occur, the Odex/Chitosan-NAC composition solidifies rapidly and forms a well-developed 3D network in a short time span. Compared with typical hydrogels derived from natural materials, the Odex/Chitosan-NAC hydrogels are mechanically strong and resist degradation. The cytotoxicity potential of the hydrogels was determined by an in vitro viability assay using fibroblast as a model cell, and the results reveal that the hydrogels are noncytotoxic. In parallel, in vivo results from subdermal implantation in mice models demonstrate that this hydrogel is not only highly resistant to degradation but also induces very mild tissue response.

Cytotoxicity and biocompatibility evaluation of N,O-carboxymethyl chitosan/oxidized alginate hydrogel for drug delivery application.

PubMed

Li, Xingyi; Kong, Xiangye; Zhang, Zhaoliang; Nan, Kaihui; Li, LingLi; Wang, XianHou; Chen, Hao

2012-06-01

In this paper, covalently cross-linked hydrogel composed of N,O-carboxymethyl chitosan and oxidized alginate was developed intending for drug delivery application. In vitro/vivo cytocompatibility and biocompatibility of the developed hydrogel were preliminary evaluated. In vitro cytocompatibility test showed that the developed hydrogel exhibited good cytocompatibility against NH3T3 cells after 3-day incubation. According to the results of acute toxicity test, there was no obvious cytotoxicity for major organs during the period of 21-day intraperitoneal administration. Meanwhile, the developed hydrogel did not induce any cutaneous reaction within 72 h of subcutaneous injection followed by slow degradation and adsorption with the time evolution. Moreover, the extraction of developed hydrogel had nearly 0% of hemolysis ratio, which indicated the good hemocompatibility of hydrogel. Based on the above results, it may be concluded that the developed N,O-carboxymethyl chitosan/oxidized alginate hydrogel with non-cytotoxicity and good biocompatibility might suitable for the various drug delivery applications. Copyright © 2012 Elsevier B.V. All rights reserved.

In situ Gelable Interpenetrating Double Network Hydrogel Formulated from Binary Components: Thiolated Chitosan and Oxidized Dextran

PubMed Central

Zhang, Hanwei; Qadeer, Aisha; Chen, Weiliam

2011-01-01

In situ gelable interpenetrating double network hydrogels composed of thiolated chitosan (Chitosan-NAC) and oxidized dextran (Odex), completely devoid of potentially cytotoxic small molecule crosslinkers and do not require complex maneuvers or catalysis, have been formulated. The interpenetrating network structure is created by Schiff base formations and disulfide bond inter-crosslinkings through exploiting the disparity of their reaction times. Compare to the auto-gelable thiolated chitosan hydrogels that typically require a relatively long time span for gelation to occur, the Odex/Chitosan-NAC composition solidifies rapidly and forms a well-developed three-dimensional network in a short time span. Compare to typical hydrogels derived from natural materials, the Odex/Chitosan-NAC hydrogels are mechanically strong and resist degradation. The cytotoxicity potential of the hydrogels was determined by an in vitro viability assay using fibroblast as a model cell and the results reveal that the hydrogels are non-cytotoxic. In parallel, in vivo results from subdermal implantation in mice models demonstrate that this hydrogel is not only highly resistant to degradation but also induces very mild tissue response. PMID:21410248

Synthesis of a chitosan-based photo-sensitive hydrogel and its biocompatibility and biodegradability.

PubMed

He, Ming; Han, Baoqin; Jiang, Zhiwen; Yang, Yan; Peng, Yanfei; Liu, Wanshun

2017-06-15

Hydroxyethyl chitosan (HECTS) is one of the most important water soluble derivatives of chitosan. In this study, photo-sensitive azidehydroxyethyl chitosan (AZ-HECTS) was synthesized with grafting degree 3.4%, and its water solution resulted in an insoluble hydrogel by 254nm UV irradiation for 90s. AZ-HECTS hydrogels, with water absorption 86.21%, had little impact on growth of mouse fibroblast (L929) and presented good cell biocompatibility. Obvious sudden degradation stage, slow degradation stage and no apparent toxicity was observed after AZ-HECTS hydrogels implanted into rats, and tissue inflammation was slighter, which indicated favorable biological safety. Furthermore, AZ-HECTS hydrogels was loaded with heparin, and released 50% of heparin accumulated 14d. AZ-HECTS-heparin hydrogels showed inhibitory effects on L929, and pro-growth functions within vascular endothelial cells seeded on the hydrogels, meanwhile a positive influence on vascular endothelial growth factor expression. In conclusion, AZ-HECTS hydrogels possessed favorable biocompatibility and biodegradability and had good potential as drug carrier. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of gellan gum-based microparticles/hydrogel matrices for application in the intervertebral disc regeneration.

PubMed

Pereira, Diana Ribeiro; Silva-Correia, Joana; Caridade, Sofia Glória; Oliveira, Joao T; Sousa, Rui A; Salgado, Antonio J; Oliveira, Joaquim M; Mano, João F; Sousa, Nuno; Reis, Rui L

2011-10-01

Low back pain is one of the most reported medical conditions associated to intervertebral disc (IVD) degeneration. Nucleus pulposus (NP) is often regarded as the structure where IVD degeneration begins. Gellan gum (GG)-based hydrogels for acellular and cellular tissue engineering strategies have been developed for finding applications as NP substitutes. The innovative strategy is based on the reinforcement of the hydrogel matrix with biocompatible and biodegradable GG microparticles (MPs), which are expected to improve the mechanical properties, while allowing to tailor its degradation rate. In this study, several GG MP/hydrogel disc formulations were prepared by means of mixing high acyl GG (0.75% (w/v)) and low acyl GG (2% (w/v)) GG aqueous solutions at different ratios, namely, 75%:25% (v/v), 50%:50% (v/v), and 25%:75% (v/v), respectively. The GG MP size was measured using a stereo microscope, and their dispersion within the hydrogel matrix was evaluated by means of staining the MPs with Toluidine Blue-O. The developed GG MPs/hydrogel discs were physicochemically characterized by Fourier-transform infrared spectroscopy and (1)H-nuclear magnetic resonance spectroscopy. The swelling behavior and degradation rate were assessed by immersion in a phosphate buffer saline for 14 days. The morphology and mechanical behavior were investigated by scanning electron microscopy and dynamic mechanical analysis, respectively. The mechanical properties of the hydrogel disc were improved by mixing the gels with the MPs. In addition, the possible cytotoxicity of the leachables released by MPs/hydrogel discs was screened in vitro, using a mouse lung fibroblast cell line (L929 cells). To investigate the encapsulation efficacy of L929 cells into the GG MPs/hydrogel discs, cells were stained with DAPI blue/Texas Red-Phalloidin and observed by confocal microscopy, after 24, 48, and 72 h of culturing. A cell viability assay was also performed using Calcein AM staining. The cell culture studies demonstrated that MPs/hydrogel discs are noncytotoxic over L929 cells. It was also demonstrated that L929 cells can be successfully encapsulated into the GG MPs of different formulations, remaining viable after 72 h of culturing. This study showed that GG hydrogel matrices reinforced with cell-loaded MPs could be a candidate strategy for NP regeneration. © Mary Ann Liebert, Inc.

Sustainable Hydrogels Based on Lignin-Methacrylate Copolymers with Enhanced Water Retention and Tunable Material Properties.

PubMed

Rajan, Kalavathy; Mann, Jeffrey K; English, Eldon; Harper, David P; Carrier, Danielle Julie; Rials, Timothy G; Labbé, Nicole; Chmely, Stephen C

2018-04-12

Synthesizing lignin-based copolymers would valorize a major coproduct stream from pulp and paper mills and biorefineries as well as reduce the dependence on petrochemical-based consumer goods. In this study, we used organosolv lignin isolated from hybrid poplar ( Populus trichocarpa × P. deltoides) to generate lignin-containing methacrylate hydrogels. The copolymer hydrogels were synthesized by first grafting 2-hydroxyethyl methacrylate (HEMA) onto lignin (OSLH) via esterification and then by free radical polymerization of OSLH with excess HEMA. The copolymer hydrogels were prepared with different stoichiometric ratios of OSLH (e.g., 0, 10, 20, and 40 wt %) with respect to HEMA. Copolymerization with OSLH led to an increase in cross-linking density, which in turn enhanced the hydrogel's material properties; we report up to 39% improvement in water retention, 20% increase in thermostability, and up to a 3 order increase in magnitude of the storage modulus ( G'). The copolymer's properties, such as water retention and glass transition temperature, could be tuned by altering the percent functionalization of lignin OH groups and the ratio of OSLH to HEMA.

Recent Developments in Thiolated Polymeric Hydrogels for Tissue Engineering Applications.

PubMed

Gajendiran, Mani; Rhee, Jae-Sung; Kim, Kyobum

2018-02-01

This review focuses on the recent strategy in the preparation of thiolated polymers and fabrication of their hydrogel matrices. The mechanism involved in the synthesis of thiolated polymers and fabrication of thiolated polymer hydrogels is exemplified with suitable schematic representations reported in the recent literature. The 2-iminothiolane namely "Traut's reagent" has been widely used for effectively thiolating the natural polymers such as collagen and gelatin, which contain free amino group in their backbone. The free carboxylic acid group containing polymers such as hyaluronic acid and heparin have been thiolated by using the bifunctional molecules such as cysteamine and L-cysteine via N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling reaction. The degree of thiolation in the polymer chain has been widely determined by using Ellman's assay method. The thiolated polymer hydrogels are prepared by disulfide bond formation (or) thiol-ene reaction (or) Michael-type addition reaction. The thiolated polymers such as thiolated gelatin are reacted with polyethylene glycol diacrylate for obtaining interpenetrating polymer network hydrogel scaffolds. Several in vitro cell culture experiments indicate that the developed thiolated polymer hydrogels exhibited biocompatibility and cellular mimicking properties. The developed hydrogel scaffolds efficiently support proliferation and differentiation of various cell types. In the present review article, the thiol-functionalized protein-based biopolymers, carbohydrate-based polymers, and some synthetic polymers have been covered with recently published research articles. In addition, the usage of new thiolated nanomaterials as a crosslinking agent for the preparation of three-dimensional tissue-engineered hydrogels is highlighted.

Pore Interconnectivity Influences Growth Factor-Mediated Vascularization in Sphere-Templated Hydrogels

PubMed Central

Somo, Sami I.; Akar, Banu; Bayrak, Elif S.; Larson, Jeffery C.; Appel, Alyssa A.; Mehdizadeh, Hamidreza; Cinar, Ali

2015-01-01

Rapid and controlled vascularization within biomaterials is essential for many applications in regenerative medicine. The extent of vascularization is influenced by a number of factors, including scaffold architecture. While properties such as pore size and total porosity have been studied extensively, the importance of controlling the interconnectivity of pores has received less attention. A sintering method was used to generate hydrogel scaffolds with controlled pore interconnectivity. Poly(methyl methacrylate) microspheres were used as a sacrificial agent to generate porous poly(ethylene glycol) diacrylate hydrogels with interconnectivity varying based on microsphere sintering conditions. Interconnectivity levels increased with sintering time and temperature with resultant hydrogel structure showing agreement with template structure. Porous hydrogels with a narrow pore size distribution (130–150 μm) and varying interconnectivity were investigated for their ability to influence vascularization in response to gradients of platelet-derived growth factor-BB (PDGF-BB). A rodent subcutaneous model was used to evaluate vascularized tissue formation in the hydrogels in vivo. Vascularized tissue invasion varied with interconnectivity. At week 3, higher interconnectivity hydrogels had completely vascularized with twice as much invasion. Interconnectivity also influenced PDGF-BB transport within the scaffolds. An agent-based model was used to explore the relative roles of steric and transport effects on the observed results. In conclusion, a technique for the preparation of hydrogels with controlled pore interconnectivity has been developed and evaluated. This method has been used to show that pore interconnectivity can independently influence vascularization of biomaterials. PMID:25603533

The type and composition of alginate and hyaluronic-based hydrogels influence the viability of stem cells of the apical papilla.

PubMed

Lambricht, Laure; De Berdt, Pauline; Vanacker, Julie; Leprince, Julian; Diogenes, Anibal; Goldansaz, Hadi; Bouzin, Caroline; Préat, Véronique; Dupont-Gillain, Christine; des Rieux, Anne

2014-12-01

The goal of the present work was to evaluate in vitro and in vivo the influence of various types and compositions of natural hydrogels on the viability and metabolic activity of SCAPs. Two alginate, three hyaluronic-based (Corgel™) hydrogel formulations and Matrigel were characterized for their mechanical, surface and microstructure properties using rheology, X-ray photoelectron spectroscopy and scanning electron microscopy, respectively. A characterized SCAP cell line (RP89 cells) was encapsulated in the different experimental hydrogel formulations. Cells were cultured in vitro, or implanted in cyclosporine treated mice. In vitro cell viability was evaluated using a Live/Dead assay and in vitro cellular metabolic activity was evaluated with a MTS assay. In vivo cell apoptosis was evaluated by a TUNEL test and RP89 cells were identified by human mitochondria immunostaining. Hydrogel composition influenced their mechanical and surface properties, and their microstructure. In vitro cell viability was above 80% after 2 days but decreased significantly after 7 days (60-40%). Viability at day 7 was the highest in Matrigel (70%) and then in Corgel 1.5 (60%). Metabolic activity increased over time in all the hydrogels, excepted in alginate SLM. SCAPs survived after 1 week in vivo with low apoptosis (<1%). The highest number of RP89 cells was found in Corgel 5.5 (140cells/mm(2)). Collectively, these data demonstrate that SCAP viability was directly modulated by hydrogel composition and suggest that a commercially available hyaluronic acid-based formulation might be a suitable delivery vehicle for SCAP-based dental pulp regeneration strategies. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Diffusion coefficients of water in biobased hydrogel polymer matrices by nuclear magnetic resonance imaging

USDA-ARS?s Scientific Manuscript database

The diffusion coefficient of water in biobased hydrogels were measured utilizing a simple NMR method. This method tracks the migration of deuterium oxide through imaging data that is fit to a diffusion equation. The results show that a 5 wt% soybean oil based hydrogel gives aqueous diffusion of 1.37...

Highly stretchable HA/SA hydrogels for tissue engineering.

PubMed

Zhu, Chengcheng; Yang, Rui; Hua, Xiaobin; Chen, Hong; Xu, Jumei; Wu, Rile; Cen, Lian

2018-04-01

A highly stretchable hyaluronic acid (HA)/sodium alginate (SA) hydrogel was developed in this study based on an interpenetrating polymer network. HA/SA hydrogels were prepared by mixing two polysaccharides followed by covalent crosslinking via epoxy groups on HA molecules and ionic crosslinking via divalent ions on SA chains sequentially. The effect of HA/SA ratio on the pore size and distribution, swelling ratio, elongation and rheological properties as well as protein loading and release properties of HA/SA hydrogels was explored. Moreover, a surface modification method, layer-by-layer (LBL) assembly technique, was applied to modify the hydrogel to evaluate the hydrogel's tenability in varying biological performance. It was then shown that the hydrogels had the pore sizes ranging from 100 to 50 μm. With the increase in SA content of the resulting hydrogels, the pore size, swelling ratio, and storage modulus (G') and loss modulus (G″) of the hydrogel all decreased, whereas the in vitro bulk weight loss was fastened. Moreover, elongation at break (EB) value increased first, reached a peak value and then decreased, that is HA8/SA1 (HA:SA = 8:1) had the highest EB value of 417%. This hydrogel could retain 33.2% of the pre-loaded protein even after 72 h, which could be further attenuated when LBL was used to shell the hydrogel. The growth of fibroblasts on HA8/SA1 hydrogel gave preliminary assessment on its suitability as a cellular carrier, while the LBL modified HA8/SA1 hydrogel also favored the anchoring of keratinocytes, further enhancing its cell carrier role for tissue regeneration, especially skin engineering.

Encapsulation of cell into monodispersed hydrogels on microfluidic device

NASA Astrophysics Data System (ADS)

Choi, Chang-Hyoung; Lee, Ji-Hye; Shim, Hyun-Woo; Lee, Nae-Rym; Jung, Jae-Hoon; Yoon, Tae-Ho; Kim, Dong-Pyo; Lee, Chang-Soo

2007-12-01

In here, we present the microfluidic approach to produce monodispersed microbeads that will contain viable cells. The utilization of microfludics is helpful to synthesize monodispersed alginate hydrogels and in situ encapsulate cell into the generating hydrogels in microfludic device. First, the condition of formation of hydrogels in multiphase flows including oil, CaCl II, and alginate was optimized. Based on the preliminary survey, microfludic device could easily manipulate the size of alginate beads having narrow size distribution. The microfluidic method manipulates the size of hydrogel microbeads from 30 to 200um with a variation less than 2%. For the proof of concept of cell entrapment, the live yeast expressing green fluorescence protein is successfully encapsulated in microfluidic device.

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel.

PubMed

Rakhshaei, Rasul; Namazi, Hassan

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV-vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Antimicrobial cellulosic hydrogel from olive oil industrial residue.

PubMed

Dacrory, Sawsan; Abou-Yousef, Hussein; Abouzeid, Ragab E; Kamel, Samir; Abdel-Aziz, Mohamed S; El-Badry, Mohamed

2018-05-25

The cellulose-based antimicrobial hydrogel was prepared from seed and husk cellulosic fibers of olive industry residues by load silver nanoparticles (AgNPs) onto grafted acrylamide monomer (Am) cellulosic fibers. The grafting approach was the free radical mechanism by utilizing ceric ammonium nitrate (CAN) as initiator in aqueous medium and N,N methylene bisacrylamide (MBAm) as a cross linker. The effect of different grafting conditions on the properties of produced hydrogels has been studied by determining the grafting parameters, i.e. concentration of Am, MBAm, grafting time and temperature to optimize grafting yield (G %), grafting efficiency (GE %), and swelling %. Characterizations of the obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, and EDX. AgNPs were grown into the prepared hydrogel. Hydrogel/AgNPs were characterized by FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The hydrogel loaded AgNPs exhibit high efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Copyright © 2018. Published by Elsevier B.V.

Novel polymer-free iridescent lamellar hydrogel for two-dimensional confined growth of ultrathin gold membranes

NASA Astrophysics Data System (ADS)

Niu, Jian; Wang, Dong; Qin, Haili; Xiong, Xiong; Tan, Pengli; Li, Youyong; Liu, Rui; Lu, Xuxing; Wu, Jian; Zhang, Ting; Ni, Weihai; Jin, Jian

2014-02-01

Hydrogels are generally thought to be formed by nano- to micrometre-scale fibres or polymer chains, either physically branched or entangled with each other to trap water. Although there are also anisotropic hydrogels with apparently ordered structures, they are essentially polymer fibre/discrete polymer chains-based network without exception. Here we present a type of polymer-free anisotropic lamellar hydrogels composed of 100-nm-thick water layers sandwiched by two bilayer membranes of a self-assembled nonionic surfactant, hexadecylglyceryl maleate. The hydrogels appear iridescent as a result of Bragg’s reflection of visible light from the periodic lamellar plane. The particular lamellar hydrogel with extremely wide water spacing was used as a soft two-dimensional template to synthesize single-crystalline nanosheets in the confined two-dimensional space. As a consequence, flexible, ultrathin and large area single-crystalline gold membranes with atomically flat surface were produced in the hydrogel. The optical and electrical properties were detected on a single gold membrane.

Evaluation of hydrogels for soft tissue adhesives in vitro and in vivo analyses

NASA Astrophysics Data System (ADS)

Yuan, Liu; Fan, Wenshuai; Han, Linyingjun; Guo, Changan; Yan, Zuoqin; Zhu, Meifang; Mo, Xiumei

2018-03-01

In this study, natural materials (sodium alginate, dextran, gelatin and carboxymethyl chitosan) were modified to get aldehyde components and amino components. Upon mixing the two-component solutions together, four kinds of Schiff base hydrogels formed successfully within 5-300 s and could seal the wound tissue. The cytotoxicity tests of hydrogel extraction solution confirmed that the hydrogels are nontoxic materials. The adhesive ability was evaluated in vivo by measuring the adhesive strength after sealing the skin incisions on the back of rats. All the hydrogels showed higher adhesive strength than that of commercial fibrin glue and the blank control. The histological staining observation by hematoxylin and eosin staining (HE) and Masson's trichrome staining (MTC) methods suggested that the hydrogels had good biocompatibility and biodegradation in vivo. They have only normal initial inflammation to skin tissue and could improve the formation of new collagen in the incision section. So, the prepared hydrogels were both safe and effective tissue adhesive, which had the great potentials to be used as skin tissue adhesive.

Design of poly(mPEGMA-co-MAA) hydrogel-based mPEG-b-PCL nanoparticles for oral meloxicam delivery.

PubMed

Shi, Yongli; Liu, Zhaomin; Yang, Yaxing; Xu, Xiaojie; Li, Yan; Li, Tong

2017-07-01

To enhance the therapeutic effects of meloxicam (MLX), we developed an oral MLX-loaded poly(ethylene glycol)-b-poly(ε-caprolactone) nanoparticles@hydrogel (MLX-NPs@hydrogel) preparation. The MLX-NPs were fabricated via a solvent evaporation method, and their morphologies were observed by a JEM-1011 transmission electron microscope (TEM). The poly(mPEGMA-co-MAA) hydrogels were synthesized, and studies on their pH sensibilities were carried out in pH1.2, 6.8, and 7.4 buffers. The final MLX-NPs@hydrogel preparation was obtained by immersing the hydrogels in the MLX-NPs suspensions (pH7.4) for 48h. The thermodynamic properties and cytotoxicity of the MLX-NPs@hydrogel preparation were also studied. TEM images illustrated that mPEG-b-PCL NPs had a uniform size distribution. The poly(mPEGMA-co-MAA) hydrogels showed an excellent pH-sensibility. Thermal gravity analysis (TGA) data suggested that the protection of hydrogels improved the stability of mPEG-b-PCL NPs. The release studies revealed that MLX-NPs@hydrogel could deliver the MLX-NPs into alkalescent environment (e.g. intestinal tract). Then, the medicated NPs released MLX at a sustained release profile. Such preparation could overcome the drawbacks of oral MLX, and enhance its therapeutic effects. Therefore, the NPs@hydrogel was a promising sustained-controlled release matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

PEG-based degradable networks for drug delivery applications

NASA Astrophysics Data System (ADS)

Ostroha, Jamie L.

The controlled delivery of therapeutic agents by biodegradable hydrogels has become a popular mechanism for drug administration in recent years. Hydrogels are three-dimensional networks of polymer chains held together by crosslinks. Although the changes which the hydrogel undergoes in solution are important to a wide range of experimental studies, they have not been investigated systematically and the factors which influence the degree of swelling have not been adequately described. Hydrogels made of poly(ethylene glycol) (PEG) will generally resist degradation in aqueous conditions, while a hydrogel made from a copolymer of poly(lactic acid) (PLA) and PEG will degrade via hydrolysis of the lactic acid group. This ability to degrade makes these hydrogels promising candidates for controlled release drug delivery systems. The goal of this research was to characterize the swelling and degradation of both degradable and non-degradable gels and to evaluate the release of different drugs from these hydrogels, where the key variable is the molecular weight of the PEG segment. These hydrogels were formed by the addition and subsequent chemically crosslinking of methacrylate end groups. During crosslinking, both PEG and LA-PEG-LA hydrogels of varied PEG molecular weight were loaded with Vitamin B12, Insulin, Haloperidol, and Dextran. It was shown that increasing PEG molecular weight produces a hydrogel with larger pores, thus increasing water uptake and degradation rate. While many environmental factors do not affect the swelling behavior, they do significantly impact the degradation of the hydrogel, and thus the release of incorporated therapeutic agents.

Heparin-based hydrogels induce human renal tubulogenesis in vitro.

PubMed

Weber, Heather M; Tsurkan, Mikhail V; Magno, Valentina; Freudenberg, Uwe; Werner, Carsten

2017-07-15

Dialysis or kidney transplantation is the only therapeutic option for end stage renal disease. Accordingly, there is a large unmet clinical need for new causative therapeutic treatments. Obtaining robust models that mimic the complex nature of the human kidney is a critical step in the development of new therapeutic strategies. Here we establish a synthetic in vitro human renal tubulogenesis model based on a tunable glycosaminoglycan-hydrogel platform. In this system, renal tubulogenesis can be modulated by the adjustment of hydrogel mechanics and degradability, growth factor signaling, and the presence of insoluble adhesion cues, potentially providing new insights for regenerative therapy. Different hydrogel properties were systematically investigated for their ability to regulate renal tubulogenesis. Hydrogels based on heparin and matrix metalloproteinase cleavable peptide linker units were found to induce the morphogenesis of single human proximal tubule epithelial cells into physiologically sized tubule structures. The generated tubules display polarization markers, extracellular matrix components, and organic anion transport functions of the in vivo renal proximal tubule and respond to nephrotoxins comparable to the human clinical response. The established hydrogel-based human renal tubulogenesis model is thus considered highly valuable for renal regenerative medicine and personalized nephrotoxicity studies. The only cure for end stage kidney disease is kidney transplantation. Hence, there is a huge need for reliable human kidney models to study renal regeneration and establish alternative treatments. Here we show the development and application of an in vitro human renal tubulogenesis model using heparin-based hydrogels. To the best of our knowledge, this is the first system where human renal tubulogenesis can be monitored from single cells to physiologically sized tubule structures in a tunable hydrogel system. To validate the efficacy of our model as a drug toxicity platform, a chemotherapy drug was incubated with the model, resulting in a drug response similar to human clinical pathology. The established model could have wide applications in the field of nephrotoxicity and renal regenerative medicine and offer a reliable alternative to animal models. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A Stimuli-Responsive Supramolecular Hydrogel for Controlled Release of Drug

NASA Astrophysics Data System (ADS)

Biswas, Subharanjan; Datta, Lakshmi Priya; Roy, Soumyajit

An inexpensive, facile, and environmentally benign method has been developed for the preparation of stimuli-responsive and self-healing polyacrylic acid-chitosan-based supramolecular hydrogels. Guanidine hydrochloride is used as the supramolecular crosslinker to form an interconnected network with polyacrylic acid-chitosan complex. Because of the dynamic equilibrium between the hydrogen-bonding sites of the components, the hydrogels were found to be self-healable and sensitive to biochemical-stimulus, such as pH. Controlled loading of drug like doxorubicin and its significant anticancer activity of such hydrogels is worth mentioning.

Structural design approaches for creating fat droplet and starch granule mimetics.

PubMed

McClements, David Julian; Chung, Cheryl; Wu, Bi-Cheng

2017-02-22

This article focuses on hydrogel-based strategies for creating reduced calorie foods with desirable physicochemical, sensory, and nutritional properties. Initially, the role of fat droplets and starch granules in foods is discussed, and then different methods for fabricating hydrogel beads are reviewed, including phase separation, antisolvent precipitation, injection, and emulsion template methods. Finally, the potential application of hydrogel beads as fat droplet and starch granule replacements is discussed. There is still a need for large-scale, high-throughout, and economical methods of fabricating hydrogel beads suitable for utilization within the food industry.

Regeneration of hyaline cartilage promoted by xenogeneic mesenchymal stromal cells embedded within elastin-like recombinamer-based bioactive hydrogels.

PubMed

Pescador, David; Ibáñez-Fonseca, Arturo; Sánchez-Guijo, Fermín; Briñón, Jesús G; Arias, Francisco Javier; Muntión, Sandra; Hernández, Cristina; Girotti, Alessandra; Alonso, Matilde; Del Cañizo, María Consuelo; Rodríguez-Cabello, José Carlos; Blanco, Juan Francisco

2017-08-01

Over the last decades, novel therapeutic tools for osteochondral regeneration have arisen from the combination of mesenchymal stromal cells (MSCs) and highly specialized smart biomaterials, such as hydrogel-forming elastin-like recombinamers (ELRs), which could serve as cell-carriers. Herein, we evaluate the delivery of xenogeneic human MSCs (hMSCs) within an injectable ELR-based hydrogel carrier for osteochondral regeneration in rabbits. First, a critical-size osteochondral defect was created in the femora of the animals and subsequently filled with the ELR-based hydrogel alone or with embedded hMSCs. Regeneration outcomes were evaluated after three months by gross assessment, magnetic resonance imaging and computed tomography, showing complete filling of the defect and the de novo formation of hyaline-like cartilage and subchondral bone in the hMSC-treated knees. Furthermore, histological sectioning and staining of every sample confirmed regeneration of the full cartilage thickness and early subchondral bone repair, which was more similar to the native cartilage in the case of the cell-loaded ELR-based hydrogel. Overall histological differences between the two groups were assessed semi-quantitatively using the Wakitani scale and found to be statistically significant (p < 0.05). Immunofluorescence against a human mitochondrial antibody three months post-implantation showed that the hMSCs were integrated into the de novo formed tissue, thus suggesting their ability to overcome the interspecies barrier. Hence, we conclude that the use of xenogeneic MSCs embedded in an ELR-based hydrogel leads to the successful regeneration of hyaline cartilage in osteochondral lesions.

Dual Cross-Linked Biofunctional and Self-Healing Networks to Generate User-Defined Modular Gradient Hydrogel Constructs.

PubMed

Wei, Zhao; Lewis, Daniel M; Xu, Yu; Gerecht, Sharon

2017-08-01

Gradient hydrogels have been developed to mimic the spatiotemporal differences of multiple gradient cues in tissues. Current approaches used to generate such hydrogels are restricted to a single gradient shape and distribution. Here, a hydrogel is designed that includes two chemical cross-linking networks, biofunctional, and self-healing networks, enabling the customizable formation of modular gradient hydrogel construct with various gradient distributions and flexible shapes. The biofunctional networks are formed via Michael addition between the acrylates of oxidized acrylated hyaluronic acid (OAHA) and the dithiol of matrix metalloproteinase (MMP)-sensitive cross-linker and RGD peptides. The self-healing networks are formed via dynamic Schiff base reaction between N-carboxyethyl chitosan (CEC) and OAHA, which drives the modular gradient units to self-heal into an integral modular gradient hydrogel. The CEC-OAHA-MMP hydrogel exhibits excellent flowability at 37 °C under shear stress, enabling its injection to generate gradient distributions and shapes. Furthermore, encapsulated sarcoma cells respond to the gradient cues of RGD peptides and MMP-sensitive cross-linkers in the hydrogel. With these superior properties, the dual cross-linked CEC-OAHA-MMP hydrogel holds significant potential for generating customizable gradient hydrogel constructs, to study and guide cellular responses to their microenvironment such as in tumor mimicking, tissue engineering, and stem cell differentiation and morphogenesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel thermal-sensitive hydrogel enhances both humoral and cell-mediated immune responses by intranasal vaccine delivery.

PubMed

Wu, Youbin; Wu, Shipo; Hou, Lihua; Wei, Wei; Zhou, Meng; Su, Zhiguo; Wu, Jie; Chen, Wei; Ma, Guanghui

2012-08-01

A novel thermal sensitive hydrogel was formulated with N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) and α, β-glycerophosphate (α, β-GP). A serial of hydrogels containing different amount of GP and HTCC with diverse quarternize degree (QD, 41%, 59%, 79.5%, and 99%) were prepared and characterized by rheological method. The hydrogel was subsequently evaluated for intranasal vaccine delivery with adenovirus based Zaire Ebola virus glycoprotein antigen (Ad-GPZ). Results showed that moderate quarternized HTCC (60% and 79.5%) hydrogel/antigen formulations induced highest IgG, IgG1, and IgG2a antibody titers in serum, as well as mucosal IgA responses in lung wash, which may attributed to the prolonged antigen residence time due to the thermal-sensitivity of this hydrogel. Furthermore, CD8(+) splenocytes for IFN-γ positive cell assay and the release profile of Th1/Th2 type cytokines (IFN-γ, IL-2, IL-10, and IL-4) showed that hydrogel/Ad-GPZ generated an overwhelmingly enhanced Th1 biased cellular immune response. In addition, this hydrogel displayed low toxicity to nasal tissue and epithelial cells even by frequently intranasal dosing of hydrogel. All these results strongly supported this hydrogel as a safe and effective delivery system for nasal immunization. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Lipophilic super-absorbent swelling gels as cleaners for use on weapons systems and platforms

USDA-ARS?s Scientific Manuscript database

Increasingly stringent environmental regulations on volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) demand the development of disruptive technologies for cleaning weapons systems and platforms. Currently employed techniques such as vapor degreasing, solvent, aqueous, or blast c...

An Optimized Centrifugal Method for Separation of Semen from Superabsorbent Polymers for Forensic Analysis.

PubMed

Camarena, Lucy R; Glasscock, Bailey K; Daniels, Demi; Ackley, Nicolle; Sciarretta, Marybeth; Seashols-Williams, Sarah J

2017-03-01

Connection of a perpetrator to a sexual assault is best performed through the confirmed presence of semen, thereby proving sexual contact. Evidentiary items can include sanitary napkins or diapers containing superabsorbent polymers (SAPs), complicating spermatozoa visualization and DNA analysis. In this report, we evaluated the impact of SAPS on the current forensic DNA workflow, developing an efficient centrifugal protocol for separating spermatozoa from SAP material. The optimized filtration method was compared to common practices of excising the top layer only, resulting in significantly higher sperm yields when a core sample of the substrate was taken. Direct isolation of the SAP-containing materials without filtering resulted in 20% sample failure; additionally, SAP material was observed in the final eluted DNA samples, causing physical interference. Thus, use of the described centrifugal-filtering method is a simple preliminary step that improves spermatozoa visualization and enables more consistent DNA yields, while also avoiding SAP interference. © 2016 American Academy of Forensic Sciences.

Superabsorbent nanocomposite synthesis of cellulose from rice husk grafted poly(acrylate acid-co-acrylamide)/bentonite

NASA Astrophysics Data System (ADS)

Helmiyati; Abbas, G. H.; Kurniawan, S.

2017-04-01

Superabsorbent nanocomposite synthesis of cellulose rice husk as the backbone with free radical polymerization method in copolymerization grafted with acrylic acid and acrylamide monomer. The cellulose was isolated from rice husk with mixture of toluene and ethanol and then hemicellulose and lignin were removed by using potassium hydroxide 4% and hydrogen peroxide 2%. The obtained cellulose rendement was 37.85%. The functional group of lignin analyzed by FTIR spectra was disappeared at wavenumber 1724 cm-1. Crystal size of the obtained isolated cellulose analyzed by XRD diffraction pattern was 34.6 nm, indicated the nanocrystal structure. Copolymerization was performed at temperature of 70°C with flow nitrogen gas. Initiator and crosslinking agent used were potassium persulfate and N‧N-methylene-bis-acrylamide. The swelling capacity of water and urea showed the results was quite satisfactory, the maximum swelling capacity in urea and water were 611.700 g/g and 451.303 g/g, respectively, and can be applied in agriculture to absorb water and urea fertilizer.

Synthesis of Superabsorbent Polymer via Inverse Suspension Method: Effect of Carbon Filler

NASA Astrophysics Data System (ADS)

Zakaria, Munirah Ezzah Tuan; Shima Jamari, Saidatul; Ling, Yeong Yi; Ghazali, Suriati

2017-05-01

This paper studies on the effect of the addition of carbon filler towards the performance of superabsorbent polymer composite (SAPc). In this work, the SAPc was synthesized using inverse suspension polymerization method. The process involved two different solutions; dispersed phase which contains partially neutralized acrylic acid, acrylamide, APS and NN-Methylenebisacrylamide, and continuous phase which contains cyclohexane, span-80 and carbon filler (at different weight percent). The optimum SAPs and filler ratio was measured in terms of water retention in soil and characterized by Mastersizer, FTIR and SEM. Biodegradability of the polymer was determined by soil burial test and SAPc with 0.02% carbon has highest biodegradability rate. SAPc with 0.04wt% carbon showed the optimal water retention percentage among all the samples. The synthesized SAPc producing spherical shapes with parallel alignment due to the addition of carbon fiber. It can be concluded that the addition of carbon fiber able to enhance the performance of the SAP composite (SAPc).

Application of superabsorbent polymers (SAP) as desiccants to dry maize and reduce aflatoxin contamination.

PubMed

Mbuge, Duncan O; Negrini, Renata; Nyakundi, Livine O; Kuate, Serge P; Bandyopadhyay, Ranajit; Muiru, William M; Torto, Baldwyn; Mezzenga, Raffaele

2016-08-01

The ability of superabsorbent polymers (SAP) in drying maize and controlling aflatoxin contamination was studied under different temperatures, drying times and SAP-to-maize ratios. Temperature and drying time showed significant influence on the aflatoxin formation. SAP-to-maize ratios between 1:1 and 1:5 showed little or no aflatoxin contamination after drying to the optimal moisture content (MC) of 13 %, while for ratios 1:10 and 1:20, aflatoxin contamination was not well controlled due to the overall higher MC and drying time, which made these ratios unsuitable for the drying process. Results clearly show that temperature, frequency of SAP change, drying time and SAP-to-maize ratio influenced the drying rate and aflatoxin contamination. Furthermore, it was shown that SAP had good potential for grain drying and can be used iteratively, which can make this system an optimal solution to reduce aflatoxin contamination in maize, particular for developing countries and resource-lacking areas.

Controlled drug release from hydrogels for contact lenses: Drug partitioning and diffusion.

PubMed

Pimenta, A F R; Ascenso, J; Fernandes, J C S; Colaço, R; Serro, A P; Saramago, B

2016-12-30

Optimization of drug delivery from drug loaded contact lenses assumes understanding the drug transport mechanisms through hydrogels which relies on the knowledge of drug partition and diffusion coefficients. We chose, as model systems, two materials used in contact lens, a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel and a silicone based hydrogel, and three drugs with different sizes and charges: chlorhexidine, levofloxacin and diclofenac. Equilibrium partition coefficients were determined at different ionic strength and pH, using water (pH 5.6) and PBS (pH 7.4). The measured partition coefficients were related with the polymer volume fraction in the hydrogel, through the introduction of an enhancement factor following the approach developed by the group of C. J. Radke (Kotsmar et al., 2012; Liu et al., 2013). This factor may be decomposed in the product of three other factors E HS , E el and E ad which account for, respectively, hard-sphere size exclusion, electrostatic interactions, and specific solute adsorption. While E HS and E el are close to 1, E ad >1 in all cases suggesting strong specific interactions between the drugs and the hydrogels. Adsorption was maximal for chlorhexidine on the silicone based hydrogel, in water, due to strong hydrogen bonding. The effective diffusion coefficients, D e , were determined from the drug release profiles. Estimations of diffusion coefficients of the non-adsorbed solutes D=D e ×E ad allowed comparison with theories for solute diffusion in the absence of specific interaction with the polymeric membrane. Copyright © 2016 Elsevier B.V. All rights reserved.

Semi-Interpenetrating polymer network hydrogels based on aspen hemicellulose and chitosan: Effect of crosslinking sequence on hydrogel properties

Treesearch

Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

2012-01-01

Semi-interpenetrating network hydrogel films were prepared using hemicellulose and chemically crosslinked chitosan. Hemicellulose was extracted from aspen by using a novel alkaline treatment and characterized by HPSEC, and consisted of a mixture of high and low molecular weight polymeric fractions. HPLC analysis of the acid hydrolysate of the hemicellulose showed that...

Pullulan-based composite scaffolds for bone tissue engineering: Improved osteoconductivity by pore wall mineralization.

PubMed

Amrita; Arora, Aditya; Sharma, Poonam; Katti, Dhirendra S

2015-06-05

Porous hydrogels have been explored for bone tissue engineering; however their poor mechanical properties make them less suitable as bone graft substitutes. Since incorporation of fillers is a well-accepted method for improving mechanical properties of hydrogels, in this work pullulan hydrogels were reinforced with nano-crystalline hydroxyapatite (nHAp) (5 wt% nHAp in hydrogel) and poly(3-hydroxybutyrate) (PHB) fibers (3 wt% fibers in hydrogel) containing nHAp (3 wt% nHAp in fibers). Addition of these fillers to pullulan hydrogel improved compressive modulus of the scaffold by 10 fold. However, the hydrophilicity of pullulan did not support adhesion and spreading of cells. To overcome this limitation, porous composite scaffolds were modified using a double diffusion method that enabled deposition of hydroxyapatite on pore walls. This method resulted in rapid and uniform coating of HAp throughout the three-dimensional scaffolds which not only rendered them osteoconductive in vitro but also led to an improvement in their compressive modulus. These results demonstrate the potential of mineralized pullulan-based composite scaffolds in non-load bearing bone tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

Robust multi-responsive supramolecular hydrogel based on a mono-component host-guest gelator.

PubMed

Cheng, Weinan; Zhao, Dongxu; Qiu, Yuan; Hu, Haisi; Wang, Hong; Wang, Qin; Liao, Yonggui; Peng, Haiyan; Xie, Xiaolin

2018-05-29

Supramolecular hydrogels have been widely investigated, but the construction of stimuli-responsive mono-component host-guest hydrogels remains a challenge in that it is still hard to balance the solubility and gelation ability of the gelator. In this work, three azobenzene-modified β-cyclodextrin derivatives with different alkyl lengths (β-CD-Azo-Cn) have been synthesized. The length of the alkyl chain dramatically influences the solubility and gelation ability of β-CD derivatives in water. Among these derivatives, β-CD-Azo-C8 possesses the lowest minimum gelation concentration (MGC). Based on the host-guest interaction between β-CD and azobenzene units in aqueous solution, which is confirmed by UV-visible and ROESY NMR spectra, the gelators self-assemble and further interwine into networks through the hydrogen bonds on the surface of β-CD cavities. Hydrogels formed by mono-component gelators can collapse under external stimuli such as heating, competition guests and hosts, and UV irradiation. When the concentration of the gelator is more than 8 wt%, the hydrogel exhibits good self-supporting ability with a storage modulus higher than 104 Pa. The gel-sol transition temperature of the hydrogel is near body temperature, indicating its potential applications in biological materials.

Interleukin-15 and cisplatin co-encapsulated thermosensitive polypeptide hydrogels for combined immuno-chemotherapy.

PubMed

Wu, Xilong; Wu, Yundi; Ye, Hongbo; Yu, Shuangjiang; He, Chaoliang; Chen, Xuesi

2017-06-10

In situ-forming thermosensitive hydrogels based on poly(ethylene glycol)-poly(γ-ethyl-l-glutamate) diblock copolymers (mPEG-b-PELG) were prepared for the co-delivery of interleukin-15 (IL-15) and cisplatin (CDDP). The polypeptide-based hydrogels as local drug delivery carriers could reduce the systemic toxicity, degrade thoroughly within 3weeks after subcutaneous injection into rats and display an acceptable biocompatibility. When incubated with mouse melanoma B16 cells, only the CDDP-treated groups had significant effects on the S phase cell-cycle arrest in melanoma cells. After a single peritumoral injection of the hydrogel containing IL-15/CDDP in C57BL/6 mice inoculated with B16F0-RFP melanoma cells, the dual drug-loaded hydrogels displayed synergistic anticancer efficacy, which was resulted from a combination of CDDP-mediated S arrest and IL-15/CDDP-induced recovery of CD8 + T cell and NK cell populations to reduce immunosuppression and enhance antitumor immunity. Hence, the as-prepared thermosensitive polypeptide hydrogels for localized and sustained co-delivery of IL-15 and CDDP may have potential for efficient treatment of melanoma. Copyright © 2017 Elsevier B.V. All rights reserved.

Versatile hydrogel-based nanocrystal microreactors towards uniform fluorescent photonic crystal supraballs

NASA Astrophysics Data System (ADS)

Zhang, Jing; Tian, Yu; Ling, Lu-Ting; Yin, Su-Na; Wang, Cai-Feng; Chen, Su

2014-12-01

Versatile hydrogel-based nanocrystal (NC) microreactors were designed in this work for the construction of uniform fluorescence colloidal photonic crystal (CPC) supraballs. The hydrogel-based microspheres with sizes ranging from 150 to 300 nm were prepared by seeded copolymerization of acrylic acid and 2-hydroxyethyl methacrylate with micrometer-sized PS seed particles. As an independent NC microreactor, the as-synthesized hydrogel microsphere can effectively capture the guest cadmium ions due to the abundant carboxyl groups inside. Followed by the introduction of chalcogenides, in situ generation of higher-uptake NCs with sizes less than 5 nm was finally realized. Additionally, with the aid of the microfluidic device, the as-obtained NC-latex hybrids can be further self-assembled to bi-functional CPC supraballs bearing brilliant structural colors and uniform fluorescence. This research offers an alternative way to finely bind CPCs with NCs, which will facilitate progress in fields of self-assembled functional colloids and photonic materials.

Sericin/Dextran Injectable Hydrogel as an Optically Trackable Drug Delivery System for Malignant Melanoma Treatment.

PubMed

Liu, Jia; Qi, Chao; Tao, Kaixiong; Zhang, Jinxiang; Zhang, Jian; Xu, Luming; Jiang, Xulin; Zhang, Yunti; Huang, Lei; Li, Qilin; Xie, Hongjian; Gao, Jinbo; Shuai, Xiaoming; Wang, Guobin; Wang, Zheng; Wang, Lin

2016-03-01

Severe side effects of cancer chemotherapy prompt developing better drug delivery systems. Injectable hydrogels are an effective site-target system. For most of injectable hydrogels, once delivered in vivo, some properties including drug release and degradation, which are critical to chemotherapeutic effects and safety, are challenging to monitor. Developing a drug delivery system for effective cancer therapy with in vivo real-time noninvasive trackability is highly desired. Although fluorescence dyes are used for imaging hydrogels, the cytotoxicity limits their applications. By using sericin, a natural photoluminescent protein from silk, we successfully synthesized a hydrazone cross-linked sericin/dextran injectable hydrogel. This hydrogel is biodegradable and biocompatible. It achieves efficient drug loading and controlled release of both macromolecular and small molecular drugs. Notably, sericin's photoluminescence from this hydrogel is directly and stably correlated with its degradation, enabling long-term in vivo imaging and real-time monitoring of the remaining drug. The hydrogel loaded with Doxorubicin significantly suppresses tumor growth. Together, the work demonstrates the efficacy of this drug delivery system, and the in vivo effectiveness of this sericin-based optical monitoring strategy, providing a potential approach for improving hydrogel design toward optimal efficiency and safety of chemotherapies, which may be widely applicable to other drug delivery systems.

Development of carboxymethyl cellulose-based hydrogel and nanosilver composite as antimicrobial agents for UTI pathogens.

PubMed

Alshehri, Saad M; Aldalbahi, Ali; Al-Hajji, Abdullah Baker; Chaudhary, Anis Ahmad; Panhuis, Marc In Het; Alhokbany, Norah; Ahamad, Tansir

2016-03-15

Silver nanoparticles (AgNPs) containing hydrogel composite were first synthesized by preparing a new hydrogel from carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and the cross-linker ethylene glycol diglycidyl ether (EGDE), followed by the incorporation of AgNPs by microwave radiation. The resulting neat hydrogels and AgNPs-hydrogel composites were characterized using spectral, thermal, microscopic analysis and X-ray diffraction (XRD) analyses. The SEM and TEM results demonstrated that the synthesized AgNPs were spherical with diameters ranging from 8 to 14nm. In addition, the XRD analysis confirmed the nanocrystalline phase of silver with face-centered cubic (FCC) crystal structure. Energy dispersive spectroscopy (EDS) analysis of the AgNPs confirmed the presence of an elemental silver signal, and no peaks of any other impurities were detected. Additionally, the antibacterial activities of the neat hydrogel and AgNPs-hydrogel composites were measured by Kirby-Bauer method against urinary tract infection (UTI) pathogens. The rheology measurement revealed that the values of storage modulus (G') were higher than that of loss modulus (G″). The AgNPs-hydrogel composites exhibited higher antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus and Proteus mirabilis compared to the corresponding neat hydrogel. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multi-scale Multi-mechanism Toughening of Hydrogels

NASA Astrophysics Data System (ADS)

Zhao, Xuanhe

Hydrogels are widely used as scaffolds for tissue engineering, vehicles for drug delivery, actuators for optics and fluidics, and model extracellular matrices for biological studies. The scope of hydrogel applications, however, is often severely limited by their mechanical properties. Inspired by the mechanics and hierarchical structures of tough biological tissues, we propose that a general principle for the design of tough hydrogels is to implement two mechanisms for dissipating mechanical energy and maintaining high elasticity in hydrogels. A particularly promising strategy for the design is to integrate multiple pairs of mechanisms across multiple length scales into a hydrogel. We develop a multiscale theoretical framework to quantitatively guide the design of tough hydrogels. On the network level, we have developed micro-physical models to characterize the evolution of polymer networks under deformation. On the continuum level, we have implemented constitutive laws formulated from the network-level models into a coupled cohesive-zone and Mullins-effect model to quantitatively predict crack propagation and fracture toughness of hydrogels. Guided by the design principle and quantitative model, we will demonstrate a set of new hydrogels, based on diverse types of polymers, yet can achieve extremely high toughness superior to their natural counterparts such as cartilages. The work was supported by NSF(No. CMMI- 1253495) and ONR (No. N00014-14-1-0528).

Effects of precursor composition and mode of crosslinking on mechanical properties of graphene oxide reinforced composite hydrogels.

PubMed

Jang, Jinhyeong; Hong, Jisu; Cha, Chaenyung

2017-05-01

Graphene oxide (GO) is increasingly investigated as a reinforcing nanofiller for various hydrogels for biomedical applications for its superior mechanical strength. However, the reinforcing mechanism of GO in different hydrogel conditions has not been extensively explored and elucidated to date. Herein, we systematically examine the effects of various types of precursor molecules (monomers vs. macromers) as well as mode of GO incorporation (physical vs. covalent) on the mechanical properties of resulting composite hydrogels. Two hydrogel types, (1) polyacrylamide hydrogels with varying concentrations of acrylamide monomers and (2) poly(ethylene glycol) (PEG) hydrogels with varying molecular weights of PEG macromers, are used as model systems. In addition, incorporation of GO is also controlled by using either unmodified GO or methacrylic GO (MGO) which allows for covalent incorporation. The results in this study demonstrate that the interaction between GO and the surrounding network and its effect on the mechanical properties (i.e. rigidity and toughness) of composite hydrogels are highly dependent on both the type and concentration of precursors and the mode of crosslinking. We expect this study will provide an important guideline for future research efforts on controlling the mechanical properties of GO-based composite hydrogels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Morphological, electrical & antibacterial properties of trilayered Cs/PAA/PPy bionanocomposites hydrogel based on Fe3O4-NPs.

PubMed

Youssef, A M; Abdel-Aziz, M E; El-Sayed, E S A; Abdel-Aziz, M S; Abd El-Hakim, A A; Kamel, S; Turky, G

2018-09-15

Bionanocomposites hydrogel based on conducting polymers were successfully fabricated from chitosan/polyacrylic acid/polypyrrole (CS/PAA/PPy) as well as the magnetite nanoparticle (Fe 3 O 4 -NPs) was prepared via co-precipitation method. In addition, different ratios of Fe 3 O 4 -NPs were added to the prepared bionanocomposites to enhance the antimicrobial and the electrical conductivity of the prepared conductive hydrogel. Furthermore, the morphology, the swelling percent, antimicrobial activity and the dielectric properties of the prepared conducting bionanocomposites hydrogel were investigated. The antibacterial activities of the experienced microbes were improved with the increasing the loading of Fe 3 O 4 -NPs in conducting Bio-nanocomposites hydrogel. Moreover, the DC-conductivity was examined and our resulted indicated that the DC-conductivity was enhanced by increasing the loadings of Fe 3 O 4 -NPs compared to that of the pure CS/PAA as well as CS/PAA/PPy. Copyright © 2018 Elsevier Ltd. All rights reserved.

Recognition-Mediated Hydrogel Swelling Controlled by Interaction with a Negative Thermoresponsive LCST Polymer.

PubMed

Belal, Khaled; Stoffelbach, François; Lyskawa, Joël; Fumagalli, Matthieu; Hourdet, Dominique; Marcellan, Alba; Smet, Lieselot De; de la Rosa, Victor R; Cooke, Graeme; Hoogenboom, Richard; Woisel, Patrice

2016-11-02

Most polymeric thermoresponsive hydrogels contract upon heating beyond the lower critical solution temperature (LCST) of the polymers used. Herein, we report a supramolecular hydrogel system that shows the opposite temperature dependence. When the non-thermosesponsive hydrogel NaphtGel, containing dialkoxynaphthalene guest molecules, becomes complexed with the tetra cationic macrocyclic host CBPQT 4+ , swelling occurred as a result of host-guest complex formation leading to charge repulsion between the host units, as well as an osmotic contribution of chloride counter-ions embedded in the network. The immersion of NaphtGel in a solution of poly(N-isopropylacrylamide) with tetrathiafulvalene (TTF) end groups complexed with CBPQT 4+ induced positive thermoresponsive behaviour. The LCST-induced dethreading of the polymer-based pseudorotaxane upon heating led to transfer of the CBPQT 4+ host and a concomitant swelling of NaphtGel. Subsequent cooling led to reformation of the TTF-based host-guest complexes in solution and contraction of the hydrogel. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Hydrogel based approaches for cardiac tissue engineering.

PubMed

Saludas, Laura; Pascual-Gil, Simon; Prósper, Felipe; Garbayo, Elisa; Blanco-Prieto, María

2017-05-25

Heart failure still represents the leading cause of death worldwide. Novel strategies using stem cells and growth factors have been investigated for effective cardiac tissue regeneration and heart function recovery. However, some major challenges limit their translation to the clinic. Recently, biomaterials have emerged as a promising approach to improve delivery and viability of therapeutic cells and proteins for the regeneration of the damaged heart. In particular, hydrogels are considered one of the most promising vehicles. They can be administered through minimally invasive techniques while maintaining all the desirable characteristics of drug delivery systems. This review discusses recent advances made in the field of hydrogels for cardiac tissue regeneration in detail, focusing on the type of hydrogel (conventional, injectable, smart or nano- and micro-gel), the biomaterials used for its manufacture (natural, synthetic or hybrid) and the therapeutic agent encapsulated (stem cells or proteins). We expect that these novel hydrogel-based approaches will open up new possibilities in drug delivery and cell therapies. Copyright © 2016 Elsevier B.V. All rights reserved.

Release of Cyclic Phosphatidic Acid from Gelatin-based Hydrogels Inhibit Colon Cancer Cell Growth and Migration

PubMed Central

Tsukahara, Tamotsu; Murakami-Murofushi, Kimiko

2012-01-01

Microparticle and nanoparticle formulations are widely used to improve the bioavailability of low-solubility drugs and as vehicles for organ- and tissue-specific targeted drug delivery. We investigated the effect of a novel, controlled-release form of a bioactive lipid, cyclic phosphatidic acid (cPA), on human colon cancer cell line functions. We encapsulated cPA in gelatin-based hydrogels and examined its ability to inhibit the viability and migration of HT-29 and DLD-1 cells in vitro and the LPA-induced activity of the transcription factor peroxisome proliferator-activated receptor gamma (PPARγ). The hydrogel delivery system prolonged cPA release into the culture medium. Accordingly, cPA-hydrogel microspheres substantially inhibited LPA-induced PPARγ activity and cell growth and migration compared with that of cells cultured with cPA alone. Thus, hydrogel microspheres are a potential system for stable and efficient delivery of bioactive lipids such as cPA and may offer a new strategy for targeted colon cancer treatment. PMID:23008752

Combination of a peptide-modified gellan gum hydrogel with cell therapy in a lumbar spinal cord injury animal model.

PubMed

Gomes, Eduardo D; Mendes, Sofia S; Leite-Almeida, Hugo; Gimble, Jeffrey M; Tam, Roger Y; Shoichet, Molly S; Sousa, Nuno; Silva, Nuno A; Salgado, António J

2016-10-01

Spinal Cord Injury (SCI) is a highly incapacitating condition for which there is still no cure. Current clinical approaches are mainly based on palliative care, so there is a need to find possible treatments to SCI. Cellular transplantation is regarded with great expectation due to the therapeutic potential of cells such as Adipose tissue-derived Stromal/Stem Cells (ASCs) or Olfactory Ensheathing Cells (OECs). Both are accessible sources and present positive paracrine and cell-to-cell interactions, previously reported by our group. Additionally, biomaterials such as hydrogels have been applied in SCI repair with promising results. We propose to combine a GRGDS-modified gellan gum hydrogel with ASCs and OECs in order to promote SCI regeneration. In vitro, ASCs and OECs could be co-cultured within GG-GRGDS hydrogels inducing a more robust neurite outgrowth when compared to controls. In vivo experiments in a hemisection SCI rat model revealed that the administration of ASCs and OECs encapsulated in a GG-GRGDS hydrogel led to significant motor improvements when compared to both control (SCI) and hydrogel alone (GG-GRGDS) groups. This was accompanied by a decreased infiltration of inflammatory cells and astrocytes, and by an increased intensity of neurofilament. These results suggest evident gains induced by the encapsulation of ASCs and OECs in GG-GRGDS based hydrogels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microfluidic bioassay system based on microarrays of hydrogel sensing elements entrapping quantum dot-enzyme conjugates.

PubMed

Jang, Eunji; Kim, Sinyoung; Koh, Won-Gun

2012-01-15

This paper presents a simple method to fabricate a microfluidic biosensor that is able to detect substrates for H(2)O(2)-generating oxidase. The biosensor consists of three components (quantum dot-enzyme conjugates, hydrogel microstructures, and a set of microchannels) that were hierarchically integrated into a microfluidic device. The quantum dot (QD)-enzyme conjugates were entrapped within the poly(ethylene glycol) (PEG)-based hydrogel microstructures that were fabricated within the microchannels by a photopatterning process. Glucose oxidase (GOX) and alcohol oxidase (AOX) were chosen as the model oxidase enzymes, conjugated to carboxyl-terminated CdSe/ZnS QDs, and entrapped within the hydrogel microstructures, which resulted in a fluorescent hydrogel microarray that was responsive to glucose or alcohol. The hydrogel-entrapped GOX and AOX were able to perform enzyme-catalyzed oxidation of glucose and alcohol, respectively, to produce H(2)O(2), which subsequently quenched the fluorescence of the conjugated QDs. The fluorescence intensity of the hydrogel microstructures decreased as the glucose and alcohol concentrations increased, and the detection limits of this system were found to be 50 μM of glucose and 70 μM of alcohol. Because each microchannel was able to carry out different assays independently, the simultaneous detection of glucose and alcohol was possible using our novel microfluidic device composed of multiple microchannels. Copyright © 2011 Elsevier B.V. All rights reserved.

The effects of cross-linked thermo-responsive PNIPAAm-based hydrogel injection on retinal function.

PubMed

Turturro, Sanja B; Guthrie, Micah J; Appel, Alyssa A; Drapala, Pawel W; Brey, Eric M; Pérez-Luna, Victor H; Mieler, William F; Kang-Mieler, Jennifer J

2011-05-01

There is significant interest in biomaterials that provide sustained release of therapeutic molecules to the retina. Poly(N-isopropylacrylamide) (PNIPAAm)-based materials have received significant attention as injectable drug delivery platforms due to PNIPAAm's thermo-responsive properties at approximately 32 °C. While the drug delivery properties of PNIPAAm materials have been studied extensively, there is a need to evaluate the safety effects of hydrogel injection on retinal function. The purpose of this study was to examine the effect of poly(ethylene glycol) diacrylate (PEG-DA) crosslinked PNIPAAm hydrogel injection on retinal function. Utilizing scanning laser ophthalmoscopy (SLO), optical coherent tomography (OCT), and electroretinography (ERG), retinal function was assessed following hydrogel injection. In region near the hydrogel, there was a significant decrease in arterial and venous diameters (∼4%) and an increase in venous blood velocity (∼8%) 1 week post-injection. Retinal thickness decreased (∼6%) at 1 week and the maximum a- and b-wave amplitudes of ERG decreased (∼15%). All data returned to baseline values after week 1. These data suggest that the injection of PEG-DA crosslinked PNIPAAm hydrogel results in a small transient effect on retinal function without any long-term effects. These results further support the potential of PNIPAAm-based materials as an ocular drug delivery platform. Copyright © 2011 Elsevier Ltd. All rights reserved.

Biological performance of cell-encapsulated methacrylated gellan gum-based hydrogels for nucleus pulposus regeneration.

PubMed

Tsaryk, Roman; Silva-Correia, Joana; Oliveira, Joaquim Miguel; Unger, Ronald E; Landes, Constantin; Brochhausen, Christoph; Ghanaati, Shahram; Reis, Rui L; Kirkpatrick, C James

2017-03-01

Limitations of current treatments for intervertebral disc (IVD) degeneration have promoted interest in the development of tissue-engineering approaches. Injectable hydrogels loaded with cells can be used as a substitute material for the inner IVD part, the nucleus pulposus (NP), and provide an opportunity for minimally invasive treatment of IVD degeneration. The NP is populated by chondrocyte-like cells; therefore, chondrocytes and mesenchymal stem cells (MSCs), stimulated to differentiate along the chondrogenic lineage, could be used to promote NP regeneration. In this study, the in vitro and in vivo response of human bone marrow-derived MSCs and nasal chondrocytes (NCs) to modified gellan gum-based hydrogels was investigated. Both ionic- (iGG-MA) and photo-crosslinked (phGG-MA) methacrylated gellan gum hydrogels show no cytotoxicity in extraction assays with MSCs and NCs. Furthermore, the materials do not induce pro-inflammatory responses in endothelial cells. Moreover, MSCs and NCs can be encapsulated into the hydrogels and remain viable for at least 2 weeks, although apoptosis is observed in phGG-MA. Importantly, encapsulated MSCs and NCs show signs of in vivo chondrogenesis in a subcutaneous implantation of iGG-MA. Altogether, the data endorse the potential use of modified gellan gum-based hydrogel as a suitable material in NP tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

Cell-specific and pH-sensitive nanostructure hydrogel based on chitosan as a photosensitizer carrier for selective photodynamic therapy.

PubMed

Belali, Simin; Karimi, Ali Reza; Hadizadeh, Mahnaz

2018-04-15

The major problems of porphyrins as promising materials for photodynamic therapy (PDT) are their low solubility, subsequently aggregation in biological environments, and a lack of tumor selectivity. With this in mind, a chitosan-based hydrogel conjugated with tetrakis(4-aminophenyl)porphyrin (NH 2 -TPP) and 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine (TRIPOD) via Schiff base linkage, functionalized with folate was designed and synthesized as a pH-sensitive, self-healable and injectable targeted PS delivery system. This new hydrogel was characterized by FT-IR, 1 H NMR, SEM, UV-vis, fluorescence spectroscopy and zeta potential. Formation of imine bonds with the aldehyde group of TRIPOD and amine group of NH 2 -TPP and chitosan, as a dynamic connection, was approved by rheological analysis. Spectroscopic characterizations revealed that aggregation of porphyrin in aqueous media was eliminated due to diminished π stacking interaction of porphyrin in 3D cross-linked hydrogel structure. Hydrogel 3D microporous structure efficiently transfers the excitation energy to the porphyrin unit, yielding improvement singlet oxygen releases. Cytotoxicity and phototoxicity analysis of the CS/NH 2 -TPP/FA hydrogels indicating an excellent capability to kill cancer cells selectively and prevent damage to normal cells. This work presents a new and efficient model for the preparation of highly efficient and targeting photosensitizer delivery system. Copyright © 2018. Published by Elsevier B.V.

Phase separation of in situ forming poly (lactide-co-glycolide acid) implants investigated using a hydrogel-based subcutaneous tissue surrogate and UV-vis imaging.

PubMed

Sun, Yu; Jensen, Henrik; Petersen, Nickolaj J; Larsen, Susan W; Østergaard, Jesper

2017-10-25

Phase separation of in situ forming poly (lactide-co-glycolide acid) (PLGA) implants with agarose hydrogels as the provider of nonsolvent (water) mimicking subcutaneous tissue was investigated using a novel UV-vis imaging-based analytical platform. In situ forming implants of PLGA-1-methyl-2-pyrrolidinone and PLGA-triacetin representing fast and slow phase separating systems, respectively, were evaluated using this platform. Upon contact with the agarose hydrogel, the phase separation of the systems was followed by the study of changes in light transmission and absorbance as a function of time and position. For the PLGA-1-methyl-2-pyrrolidinone system, the rate of spatial phase separation was determined and found to decrease with increasing the PLGA concentration from 20% to 40% (w/w). Hydrogels with different agarose concentrations (1% and 10% (w/v)) were prepared for providing the nonsolvent, water, to the in situ forming PLGA implants simulating the injection site environment. The resulting implant morphology depended on the stiffness of hydrogel matrix, indicating that the matrix in which implants are formed is of importance. Overall, the work showed that the UV-vis imaging-based platform with an agarose hydrogel mimicking the subcutaneous tissue holds potential in providing bio-relevant and mechanistic information on the phase separation processes of in situ forming implants. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-degradation of tissue adhesive based on oxidized dextran and poly-L-lysine.

PubMed

Matsumura, Kazuaki; Nakajima, Naoki; Sugai, Hajime; Hyon, Suong-Hyu

2014-11-26

We have developed a low-toxicity bioadhesive based on oxidized dextran and poly-L-lysine. Here, we report that the mechanical properties and degradation of this novel hydrogel bioadhesive can be controlled by changing the extent of oxidation of the dextran and the type or concentration of the anhydride species in the acylated poly-L-lysine. The dynamic moduli of the hydrogels can be controlled from 120 Pa to 20 kPa, suggesting that they would have mechanical compatibility with various tissues, and could have applications as tissue adhesives. Development of the hydrogel color from clear to brown indicates that the reaction between the dextran aldehyde groups and the poly-L-lysine amino groups may be induced by a Maillard reaction via Schiff base formation. Degradation of the aldehyde dextran may begin by reaction of the amino groups in the poly-L-lysine. The gel degradation can be ascribed to degradation of the aldehyde dextran in the hydrogel, although the aldehyde dextran itself is relatively stable in water. The oxidized dextran and poly-L-lysine, and the degraded hydrogel showed low cytotoxicities. These findings indicate that a hydrogel consisting of oxidized dextran and poly-L-lysine has low toxicity and a well-controlled degradation rate, and has potential clinical applications as a bioadhesive. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cell recruiting chemokine-loaded sprayable gelatin hydrogel dressings for diabetic wound healing.

PubMed

Yoon, Dong Suk; Lee, Yunki; Ryu, Hyun Aae; Jang, Yeonsue; Lee, Kyoung-Mi; Choi, Yoorim; Choi, Woo Jin; Lee, Moses; Park, Kyung Min; Park, Ki Dong; Lee, Jin Woo

2016-07-01

In this study, we developed horseradish peroxidase (HRP)-catalyzed sprayable gelatin hydrogels (GH) as a bioactive wound dressing that can deliver cell-attracting chemotactic cytokines to the injured tissues for diabetic wound healing. We hypothesized that topical administration of chemokines using GH hydrogels might improve wound healing by inducing recruitment of the endogenous cells. Two types of chemokines (interleukin-8; IL-8, macrophage inflammatory protein-3α; MIP-3α) were simply loaded into GH hydrogels during in situ cross-linking, and then their wound-healing effects were evaluated in streptozotocin-induced diabetic mice. The incorporation of chemokines did not affect hydrogels properties including swelling ratio and mechanical stiffness, and the bioactivities of IL-8 and MIP-3α released from hydrogel matrices were stably maintained. In vivo transplantation of chemokine-loaded GH hydrogels facilitated cell infiltration into the wound area, and promoted wound healing with enhanced re-epithelialization/neovascularization and increased collagen deposition, compared with no treatment or the GH hydrogel alone. Based on our results, we suggest that cell-recruiting chemokine-loaded GH hydrogel dressing can serve as a delivery platform of various therapeutic proteins for wound healing applications. Despite development of materials combined with therapeutic agents for diabetic wound treatment, impaired wound healing by insufficient chemotactic responses still remain as a significant problem. In this study, we have developed enzyme-catalyzed gelatin (GH) hydrogels as a sprayable dressing material that can deliver cell-attracting chemokines for diabetic wound healing. The chemotactic cytokines (IL-8 and MIP-3α) were simply loaded within hydrogel during in situ gelling, and wound healing efficacy of chemokine-loaded GH hydrogels was investigated in STZ-induced diabetic mouse model. These hydrogels significantly promoted wound-healing efficacy with faster wound closure, neovascularization, and thicker granulation. Therefore, we expect that HRP-catalyzed in situ forming GH hydrogels can serve as an injectable/sprayable carrier of various therapeutic agents for wound healing applications. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Modified pineapple peel cellulose hydrogels embedded with sepia ink for effective removal of methylene blue.

PubMed

Dai, Hongjie; Huang, Huihua

2016-09-05

Novel composite hydrogels based on pineapple peel cellulose and sepia ink were synthesized by homogeneous acetylation of cellulose in ionic liquid 1-butyl-3-methylimidazolium chloride. The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, thermogravimetry and differential scanning calorimetry. The effects of acetylation time, acetylation temperature, molar ratio of acetic anhydride/anhydroglucose unit and the additive amount of sepia ink on methylene blue adsorption capacity of the hydrogels embedded with sepia ink were also investigated. Methylene blue adsorption of the hydrogels followed pseudo-second-order kinetic model and sepia ink improved adsorption capacity significantly. The adsorption capacity at equilibrium was increased from 53.72 to 138.25mg/g when the additive amount of sepia ink of the hydrogels was 10%. Copyright © 2016 Elsevier Ltd. All rights reserved.

A mini review on hydrogels classification and recent developments in miscellaneous applications.

PubMed

Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Yallapu, Murali Mohan; Sadiku, Rotimi

2017-10-01

Hydrogels are composed of three-dimensional smart and/or hungry networks, which do not dissolve in water but swell considerably in an aqueous medium, demonstrating an extraordinary ability to absorb water into the reticulated structure. Such inherent feature is a subject of considerable scientific research interest which leads to a dominating path in extending their potential in hi-tech applications. Over the past decades, significant progress has been made in the field of hydrogels. Further, explorations are continuously being made in all directions at an accelerated pace for their extensive usage. In view of this, the present review discusses the subject on the miscellaneous hydrogels with regard to their raw materials, methods of fabrication and applications. In addition, this article summarizes the classification of hydrogels, based on their cross-linking and physical states. Lately, a brief outlook on the future prospects of hydrogels is also presented. Copyright © 2017 Elsevier B.V. All rights reserved.

Optical sensing properties of Au nanoparticle/hydrogel composite microbeads using droplet microfluidics

NASA Astrophysics Data System (ADS)

Li, Huilin; Men, Dandan; Sun, Yiqiang; Zhang, Tao; Hang, Lifeng; Liu, Dilong; Li, Cuncheng; Cai, Weiping; Li, Yue

2017-10-01

Uniform Au nanoparticle (NP)/poly (acrylamide-co-acrylic acid) [P(AAm-co-AA)] hydrogel microbeads were successfully prepared using droplet microfluidics technology. The microbeads exhibited a good stimuli-responsive behavior to pH value. Particularly in the pH value ranging from pH 2-pH 9, the composite microbead sizes gradually increased along with the increase of pH value. The homogeneous Au NPs, which were encapsulated in the P(AAm-co-AA) hydrogel microbeads, could transform the volume changes of hydrogel into optical signals by a tested single microbead with a microspectrometre system. The glucose was translated into gluconic acid by glucose oxidase. Thus, the Au NP/P(AAm-co-AA) hydrogel microbeads were used for detecting glucose based on pH effects on the composite microbeads. For this, the single Au NP/P(AAm-co-AA) hydrogel microbead could act as a good pH- or glucose-visualizing sensor.

Mussel-inspired synthesis of polydopamine-functionalized graphene oxide hydrogel as broad-spectrum antimicrobial material

NASA Astrophysics Data System (ADS)

Wang, Xinpeng; Liu, Zhiming; Zhong, Huiqing; Guo, Zhouyi; Yuan, Xiaochan

2014-09-01

Recently, three-dimensional GO-based hydrogels have attracted great attention due to the unique advantages. It is generally know that bacteria are everywhere and many of them could cause the diseases and threaten human health. However, developing new antibacterial materials with high-efficiency, low cost, broad-spectrum, and easy recycling is still a great challenge. Herein, inspired by mussel, we synthesized benzalkonium bromide/polydopamine/reduced graphene oxide hydrogel (BKB/PDA/rGOG). The as-prepared three-dimensional hydrogels were characterized by scanning eletron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The resultant hydrogels exhibited strong antibacterial effects to both Gram-negative and Gram-positive bacteria due to the synergistic effect of graphene oxide and benzalkonium bromide. In addition, the resultant hydrogels could be removed easily from the resolution, which was undoubtedly good news for industry application.

Matrix-Assisted Three-Dimensional Printing of Cellulose Nanofibers for Paper Microfluidics.

PubMed

Shin, Sungchul; Hyun, Jinho

2017-08-09

A cellulose nanofiber (CNF), one of the most attractive green bioresources, was adopted for construction of microfluidic devices using matrix-assisted three-dimensional (3D) printing. CNF hydrogels can support structures printed using CAD design in a 3D hydrogel environment with the appropriate combination of rheological properties between the CNF hydrogel and ink materials. Amazingly, the structure printed freely in the bulky CNF hydrogels was able to retain its highly resolved 3D features in an ultrathin two-dimensional (2D) paper using a simple drying process. The dimensional change in the CNF hydrogels from 3D to 2D resulted from simple dehydration of the CNFs and provided transparent, stackable paper-based 3D channel devices. As a proof of principle, the rheological properties of the CNF hydrogels, the 3D structure of the ink, the formation of channels by evacuation of the ink, and the highly localized selectivity of the devices are described.

Cellulose Anionic Hydrogels Based on Cellulose Nanofibers As Natural Stimulants for Seed Germination and Seedling Growth.

PubMed

Zhang, Hao; Yang, Minmin; Luan, Qian; Tang, Hu; Huang, Fenghong; Xiang, Xia; Yang, Chen; Bao, Yuping

2017-05-17

Cellulose anionic hydrogels were successfully prepared by dissolving TEMPO-oxidized cellulose nanofibers in NaOH/urea aqueous solution and being cross-linked with epichlorohydrin. The hydrogels exhibited microporous structure and high hydrophilicity, which contribute to the excellent water absorption property. The growth indexes, including the germination rate, root length, shoot length, fresh weight, and dry weight of the seedlings, were investigated. The results showed that cellulose anionic hydrogels with suitable carboxylate contents as plant growth regulators could be beneficial for seed germination and growth. Moreover, they presented preferable antifungal activity during the breeding and growth of the sesame seed breeding. Thus, the cellulose anionic hydrogels with suitable carboxylate contents could be applied as soilless culture mediums for plant growth. This research provided a simple and effective method for the fabrication of cellulose anionic hydrogel and evaluated its application in agriculture.

Kinetically Controlled Lifetimes in Redox-Responsive Transient Supramolecular Hydrogels.

PubMed

Wojciechowski, Jonathan P; Martin, Adam D; Thordarson, Pall

2018-02-28

It remains challenging to program soft materials to show dynamic, tunable time-dependent properties. In this work, we report a strategy to design transient supramolecular hydrogels based on kinetic control of competing reactions. Specifically, the pH-triggered self-assembly of a redox-active supramolecular gelator, N,N'-dibenzoyl-l-cystine (DBC) in the presence of a reducing agent, which acts to disassemble the system. The lifetimes of the transient hydrogels can be tuned simply by pH or reducing agent concentration. We find through kinetic analysis that gel formation hinders the ability of the reducing agent and enables longer transient hydrogel lifetimes than would be predicted. The transient hydrogels undergo clean cycles, with no kinetically trapped aggregates observed. As a result, multiple transient hydrogel cycles are demonstrated and can be predicted. This work contributes to our understanding of designing transient assemblies with tunable temporal control.

Effect of heterocyclic capping groups on the self-assembly of a dipeptide hydrogel.

PubMed

Martin, Adam D; Wojciechowski, Jonathan P; Warren, Holly; in het Panhuis, Marc; Thordarson, Pall

2016-03-14

The mechanism and design rules associated with the self-assembly of short peptides into hydrogels is currently not well understood. In this work, four diphenylalanine-based peptides have been synthesised, bearing heterocyclic capping groups which have different degrees of hydrogen bonding potential and nitrogen substitution. For these four peptides, zeta potential and electrical impedance spectroscopy measurements were undertaken to monitor gelation, with the impedance data showing different gelation times for each peptide hydrogel. Through a combination of atomic force microscopy and rheological measurmeents, including dynamic strain and frequency sweeps, and thixotropic tests, the relationship between the mechanism of self-assembly in these hydrogels and their macroscopic behaviour can be established. It is observed that the degree of nitrogen substitution affects the self-assembly mechanisms of the hydrogels and as such, that there is an interplay between branching and bundling self-assembly pathways that are responsible for the final properties of each hydrogel.

Study of soybean oil-based polymers for controlled release anticancer drugs

USDA-ARS?s Scientific Manuscript database

Soybean oil-based polymers were prepared by the ring-opening polymerization of epoxidized soybean oil with Lewis acid catalyst. The formed polymers (HPESO) could be converted into hydrogels through hydrolysis. Characterization and viscoelastic properties of this soy hydrogel and application in contr...

Recent Advances in Edible Polymer Based Hydrogels as a Sustainable Alternative to Conventional Polymers.

PubMed

Ali, Akbar; Ahmed, Shakeel

2018-06-26

The over increasing demand of eco-friendly materials to counter various problems, such as environmental issues, economics, sustainability, biodegradability, and biocompatibility, open up new fields of research highly focusing on nature-based products. Edible polymer based materials mainly consisting of polysaccharides, proteins, and lipids could be a prospective contender to handle such problems. Hydrogels based on edible polymer offer many valuable properties compared to their synthetic counterparts. Edible polymers can contribute to the reduction of environmental contamination, advance recyclability, provide sustainability, and thereby increase its applicability along with providing environmentally benign products. This review is highly emphasizing on toward the development of hydrogels from edible polymer, their classification, properties, chemical modification, and their potential applications. The application of edible polymer hydrogels covers many areas including the food industry, agricultural applications, drug delivery to tissue engineering in the biomedical field and provide more safe and attractive products in the pharmaceutical, agricultural, and environmental fields, etc.

Toward a versatile toolbox for cucurbit[n]uril-based supramolecular hydrogel networks through in situ polymerization.

PubMed

Liu, Ji; Soo Yun Tan, Cindy; Lan, Yang; Scherman, Oren A

2017-09-15

The success of exploiting cucurbit[ n ]uril (CB[ n ])-based molecular recognition in self-assembled systems has sparked a tremendous interest in polymer and materials chemistry. In this study, polymerization in the presence of host-guest complexes is applied as a modular synthetic approach toward a diverse set of CB[8]-based supramolecular hydrogels with desirable properties, such as mechanical strength, toughness, energy dissipation, self-healing, and shear-thinning. A range of vinyl monomers, including acrylamide-, acrylate-, and imidazolium-based hydrophilic monomers, could be easily incorporated as the polymer backbones, leading to a library of CB[8] hydrogel networks. This versatile strategy explores new horizons for the construction of supramolecular hydrogel networks and materials with emergent properties in wearable and self-healable electronic devices, sensors, and structural biomaterials. © 2017 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3105-3109.

pH responsive cross-linked polymeric matrices based on natural polymers: effect of process variables on swelling characterization and drug delivery properties.

PubMed

Naeem, Fahad; Khan, Samiullah; Jalil, Aamir; Ranjha, Nazar Muhammad; Riaz, Amina; Haider, Malik Salman; Sarwar, Shoaib; Saher, Fareha; Afzal, Samrin

2017-01-01

Introduction: The current work was aimed to design and synthesize novel crosslinked pH-sensitive gelatin/pectin (Ge/Pec) hydrogels using different polymeric ratios and to explore the effect of polymers and degree of crosslinking on dynamic, equilibrium swelling and in vitro release behavior of the model drug (Mannitol). Methods: The Ge/Pec based hydrogels were prepared using glutaraldehyde as the crosslinker. Various structural parameters that affect their release behavior were determined, including swelling study, porosity, sol-gel analysis, average molecular weight between crosslinks (Mc), volume fraction of polymer (V2,s), solvent interaction parameter (χ) and diffusion coefficient. The synthesized hydrogels were subjected to various characterization tools like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and DSC differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Results: The hydrogels show highest water uptake and release at lower pH values. The FTIR spectra showed an interaction between Ge and Pec, and the drug-loaded samples also showed the drug-related peaks, indicating proper loading of the drug. DSC and TGA studies confirmed the thermal stability of hydrogel samples, while SEM showed the porous nature of hydrogels. The drug release followed non-Fickian diffusion or anomalous mechanism. Conclusion: Aforementioned characterizations reveal the successful formation of copolymer hydrogels. The pH-sensitive swelling ability and drug release behavior suggest that the rate of polymer chain relaxation and drug diffusion from these hydrogels are comparable which also predicts their possible use for site-specific drug delivery.

pH responsive cross-linked polymeric matrices based on natural polymers: effect of process variables on swelling characterization and drug delivery properties

PubMed Central

Naeem, Fahad; Khan, Samiullah; Jalil, Aamir; Ranjha, Nazar Muhammad; Riaz, Amina; Haider, Malik Salman; Sarwar, Shoaib; Saher, Fareha; Afzal, Samrin

2017-01-01

Introduction: The current work was aimed to design and synthesize novel crosslinked pH-sensitive gelatin/pectin (Ge/Pec) hydrogels using different polymeric ratios and to explore the effect of polymers and degree of crosslinking on dynamic, equilibrium swelling and in vitro release behavior of the model drug (Mannitol). Methods: The Ge/Pec based hydrogels were prepared using glutaraldehyde as the crosslinker. Various structural parameters that affect their release behavior were determined, including swelling study, porosity, sol-gel analysis, average molecular weight between crosslinks (Mc), volume fraction of polymer (V2,s), solvent interaction parameter (χ) and diffusion coefficient. The synthesized hydrogels were subjected to various characterization tools like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and DSC differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Results:The hydrogels show highest water uptake and release at lower pH values. The FTIR spectra showed an interaction between Ge and Pec, and the drug-loaded samples also showed the drug-related peaks, indicating proper loading of the drug. DSC and TGA studies confirmed the thermal stability of hydrogel samples, while SEM showed the porous nature of hydrogels. The drug release followed non-Fickian diffusion or anomalous mechanism. Conclusion: Aforementioned characterizations reveal the successful formation of copolymer hydrogels. The pH-sensitive swelling ability and drug release behavior suggest that the rate of polymer chain relaxation and drug diffusion from these hydrogels are comparable which also predicts their possible use for site-specific drug delivery. PMID:29159145

Fluxgate magnetorelaxometry: a new approach to study the release properties of hydrogel cylinders and microspheres.

PubMed

Wöhl-Bruhn, S; Heim, E; Schwoerer, A; Bertz, A; Harling, S; Menzel, H; Schilling, M; Ludwig, F; Bunjes, H

2012-10-15

Hydrogels are under investigation as long term delivery systems for biomacromolecules as active pharmaceutical ingredients. The release behavior of hydrogels can be tailored during the fabrication process. This study investigates the applicability of fluxgate magnetorelaxometry (MRX) as a tool to characterize the release properties of such long term drug delivery depots. MRX is based on the use of superparamagnetic core-shell nanoparticles as model substances. The feasibility of using superparamagnetic nanoparticles to study the degradation of and the associated release from hydrogel cylinders and hydrogel microspheres was a major point of interest. Gels prepared from two types of photo crosslinkable polymers based on modified hydroxyethylstarch, specifically hydroxyethyl starch-hydroxyethyl methacrylate (HES-HEMA) and hydroxyethyl starch-polyethylene glycol methacrylate (HES-P(EG)(6)MA), were analyzed. MRX analysis of the incorporated nanoparticles allowed to evaluate the influence of different crosslinking conditions during hydrogel production as well as to follow the increase in nanoparticle mobility as a result of hydrogel degradation during release studies. Conventional release studies with fluorescent markers (half-change method) were performed for comparison. MRX with superparamagnetic nanoparticles as model substances is a promising method to analyze pharmaceutically relevant processes such as the degradation of hydrogel drug carrier systems. In contrast to conventional release experiments MRX allows measurements in closed vials (reducing loss of sample and sampling errors), in opaque media and at low magnetic nanoparticle concentrations. Magnetic markers possess a better long-term stability than fluorescent ones and are thus also promising for the use in in vivo studies. Copyright © 2012 Elsevier B.V. All rights reserved.

Design of a single-step immunoassay principle based on the combination of an enzyme-labeled antibody release coating and a hydrogel copolymerized with a fluorescent enzyme substrate in a microfluidic capillary device.

PubMed

Wakayama, Hideki; Henares, Terence G; Jigawa, Kaede; Funano, Shun-ichi; Sueyoshi, Kenji; Endo, Tatsuro; Hisamoto, Hideaki

2013-11-21

A combination of an enzyme-labeled antibody release coating and a novel fluorescent enzyme substrate-copolymerized hydrogel in a microchannel for a single-step, no-wash microfluidic immunoassay is demonstrated. This hydrogel discriminates the free enzyme-conjugated antibody from an antigen-enzyme-conjugated antibody immunocomplex based on the difference in molecular size. A selective and sensitive immunoassay, with 10-1000 ng mL(-1) linear range, is reported.

Equilibrium swelling properties of polyampholytic hydrogels

NASA Astrophysics Data System (ADS)

English, Anthony E.; Mafé, Salvador; Manzanares, José A.; Yu, Xiahong; Grosberg, Alexander Yu.; Tanaka, Toyoichi

1996-06-01

The role of counter ions and ion dissociation in establishing the equilibrium swelling of balanced and unbalanced polyampholytic hydrogels has been investigated experimentally and theoretically. The swelling dependence on both the net charge offset and the external bath salt concentration has been examined using an acrylamide based polyampholytic hydrogels. By careful consideration of the swelling kinetics, we illustrate the effects of ion dissociation equilibria and counter ion shielding in polyampholytic hydrogels near their balance point where both polyelectrolyte and polyampholyte effects are present. The theory considers a Flory type swelling model where the Coulombic interactions between fixed ions in the hydrogel resemble those of an ionic solid with a Debye screening factor. Theoretical predictions from this model are in qualitative agreement with our experimental results.

Cytotoxicity and metal ions removal using antibacterial biodegradable hydrogels based on N-quaternized chitosan/poly(acrylic acid).

PubMed

Mohamed, Riham R; Elella, Mahmoud H Abu; Sabaa, Magdy W

2017-05-01

Physically crosslinked hydrogels resulted from interaction between N,N,N-trimethyl chitosan chloride (N-Quaternized Chitosan) (NQC) and poly(acrylic acid) (PAA) were synthesized in different weight ratios (3:1), (1:1) and (1:3) taking the following codes Q3P1, Q1P1 and Q1P3, respectively. Characterization of the mentioned hydrogels was done using several analysis tools including; FTIR, XRD, SEM, TGA, biodegradation in simulated body fluid (SBF) and cytotoxicity against HepG-2 liver cancer cells. FTIR results proved that the prepared hydrogels were formed via electrostatic and H-bonding interactions, while XRD patterns proved that the prepared hydrogels -irrespective to their ratios- were more crystalline than both matrices NQC and PAA. TGA results, on the other hand, revealed that Q1P3 hydrogel was the most thermally stable compared to the other two hydrogels (Q3P1 and Q1P1). Biodegradation tests in SBF proved that these hydrogels were more biodegradable than the native chitosan. Examination of the prepared hydrogels for their potency in heavy metal ions removal revealed that they adsorbed Fe (III) and Cd (II) ions more than chitosan, while they adsorbed Cr (III), Ni (II) and Cu (II) ions less than chitosan. Moreover, testing the prepared hydrogels as antibacterial agents towards several Gram positive and Gram negative bacteria revealed their higher antibacterial activity as compared with NQC when used alone. Evaluating the cytotoxic effect of these hydrogels on an in vitro human liver cancer cell model (HepG-2) showed their good cytotoxic activity towards HepG-2. Moreover, the inhibition rate increased with increasing the hydrogels concentration in the culture medium. Copyright © 2017 Elsevier B.V. All rights reserved.

Establishment of a Physical Model for Solute Diffusion in Hydrogel: Understanding the Diffusion of Proteins in Poly(sulfobetaine methacrylate) Hydrogel.

PubMed

Zhou, Yuhang; Li, Junjie; Zhang, Ying; Dong, Dianyu; Zhang, Ershuai; Ji, Feng; Qin, Zhihui; Yang, Jun; Yao, Fanglian

2017-02-02

Prediction of the diffusion coefficient of solute, especially bioactive molecules, in hydrogel is significant in the biomedical field. Considering the randomness of solute movement in a hydrogel network, a physical diffusion RMP-1 model based on obstruction theory was established in this study. The physical properties of the solute and the polymer chain and their interactions were introduced into this model. Furthermore, models RMP-2 and RMP-3 were established to understand and predict the diffusion behaviors of proteins in hydrogel. In addition, zwitterionic poly(sulfobetaine methacrylate) (PSBMA) hydrogels with wide range and fine adjustable mesh sizes were prepared and used as efficient experimental platforms for model validation. The Flory characteristic ratios, Flory-Huggins parameter, mesh size, and polymer chain radii of PSBMA hydrogels were determined. The diffusion coefficients of the proteins (bovine serum albumin, immunoglobulin G, and lysozyme) in PSBMA hydrogels were studied by the fluorescence recovery after photobleaching technique. The measured diffusion coefficients were compared with the predictions of obstruction models, and it was found that our model presented an excellent predictive ability. Furthermore, the assessment of our model revealed that protein diffusion in PSBMA hydrogel would be affected by the physical properties of the protein and the PSBMA network. It was also confirmed that the diffusion behaviors of protein in zwitterionic hydrogels can be adjusted by changing the cross-linking density of the hydrogel and the ionic strength of the swelling medium. Our model is expected to possess accurate predictive ability for the diffusion coefficient of solute in hydrogel, which will be widely used in the biomedical field.

Laser-ignited frontal polymerization of shape-controllable poly(VI-co-AM) hydrogels based on 3D templates toward adsorption of heavy metal ions

NASA Astrophysics Data System (ADS)

Fan, Suzhen; Liu, Sisi; Wang, Xiao-Qiao; Wang, Cai-Feng; Chen, Su

2016-06-01

Given the increasing heavy metal pollution issue, fast preparation of polymeric hydrogels with excellent adsorption property toward heavy metal ions is very attractive. In this work, a series of poly( N-vinylimidazole-co-acrylamide) (poly(VI-co-AM)) hydrogels were synthesized via laser-ignited frontal polymerization (LIFP) for the first time. The dependence of frontal velocity and temperature on two factors monomer ratios and initiator concentrations was systematically investigated. Poly(VI-co-AM) hydrogels with any self-supporting shapes can be synthesized by a one-step LIFP in seconds through the application of 3D templates. These shape-persistent hydrogels are pH-responsive and exhibit excellent adsorption/desorption characteristics toward Mn(II), Zn(II), Cd(II), Ni(II), Cu(II) and Co(II) ions, and the adsorption conformed to the pseudo-second-order kinetic model. The reusability of the hydrogels toward mental ions adsorption was further researched, which suggested that the hydrogels can be reused without serious decrease in adsorption capacity. This work might open a promising strategy to facilely prepare shape-controllable hydrogels and expand the application of LIFP.

Glycol chitosan/oxidized hyaluronic acid hydrogels functionalized with cartilage extracellular matrix particles and incorporating BMSCs for cartilage repair.

PubMed

Liu, Chun; Liu, Deshuai; Wang, Yingying; Li, Yun; Li, Tao; Zhou, Zhiyou; Yang, Zhijian; Wang, Jianhua; Zhang, Qiqing

2018-02-05

In this article, we fabricated a bioactive hydrogel composed of glycol chitosan (G-CS) and oxidized hyaluronic acid (OHA) via Schiff base reaction. Cartilage extracellular matrix (ECM) particles with different concentrations were used to functionalize G-CS/OHA (S1) hydrogel. The results demonstrated that S3 (G-CS/OHA/ECM 2% w/v) hydrogel exhibited the most suitable compression strength and provided the optimal environment for proliferation of bone marrow mesenchymal stem cells (BMSCs). To assess the chondroinductivity of ECM in vitro, we compared the chondrogenesis of BMSCs in S1 (G-CS/OHA) and S3 (G-CS/OHA/ECM 2% w/v) hydrogels. The results confirmed that the higher levels of glycosaminoglycans (GAGs) and collagen type II (COL II) were accumulated in S3 hydrogel. In vivo, cartilage defects of rats generated most mature tissue within BMSCs-laden S3 hydrogel (S3/BMSCs group). The tissues were more integrative and contained higher levels of COL II and GAGs compared to the other groups. All these results suggested that the G-CS/OHA hydrogel functionalized with ECM particles is a good candidate biomaterial to be applied in cartilage tissue engineering.

Hydrolytically degradable poly(ethylene glycol) hydrogel scaffolds with tunable degradation and mechanical properties

PubMed Central

Zustiak, Silviya P.

2011-01-01

The objective of this work was to create three-dimensional (3D) hydrogel matrices with defined mechanical properties, as well as tunable degradability for use in applications involving protein delivery and cell encapsulation. Thus, we report the synthesis and characterization of a novel hydrolytically degradable poly(ethylene glycol) (PEG) hydrogel composed of PEG vinyl sulfone (PEG-VS) cross-linked with PEG-diester-dithiol. Unlike previously reported degradable PEG-based hydrogels, these materials are homogeneous in structure, fully hydrophilic and have highly specific cross-linking chemistry. We characterized hydrogel degradation and associated trends in mechanical properties, i.e., storage modulus (G′), swelling ratio (QM), and mesh size (ξ). Degradation time and the monitored mechanical properties of the hydrogel correlated with cross-linker molecular weight, cross-linker functionality, and total polymer density; these properties changed predictably as degradation proceeded (G′ decreased, whereas QM and ξ increased) until the gels reached complete degradation. Balb/3T3 fibroblast adhesion and proliferation within the 3D hydrogel matrices were also verified. In sum, these unique properties indicate that the reported degradable PEG hydrogels are well poised for specific applications in protein and cell delivery to repair soft tissue. PMID:20355705

Glucose-responsive hydrogel electrode for biocompatible glucose transistor

NASA Astrophysics Data System (ADS)

Kajisa, Taira; Sakata, Toshiya

2017-12-01

In this paper, we propose a highly sensitive and biocompatible glucose sensor using a semiconductor-based field effect transistor (FET) with a functionalized hydrogel. The principle of the FET device contributes to the easy detection of ionic charges with high sensitivity, and the hydrogel coated on the electrode enables the specific detection of glucose with biocompatibility. The copolymerized hydrogel on the Au gate electrode of the FET device is optimized by controlling the mixture ratio of biocompatible 2-hydroxyethylmethacrylate (HEMA) as the main monomer and vinylphenylboronic acid (VPBA) as a glucose-responsive monomer. The gate surface potential of the hydrogel FETs shifts in the negative direction with increasing glucose concentration from 10 μM to 40 mM, which results from the increase in the negative charges on the basis of the diol-binding of PBA derivatives with glucose molecules in the hydrogel. Moreover, the hydrogel coated on the gate suppresses the signal noise caused by the nonspecific adsorption of proteins such as albumin. The hydrogel FET can serve as a highly sensitive and biocompatible glucose sensor in in vivo or ex vivo applications such as eye contact lenses and sheets adhering to the skin.

ADVANCED MOLECULAR DESIGN OF BIOPOLYMERS FOR TRANSMUCOSAL AND INTRACELLULAR DELIVERY OF CHEMOTHERAPEUTIC AGENTS AND BIOLOGICAL THERAPEUTICS

PubMed Central

Liechty, William B.; Caldorera-Moore, Mary; Phillips, Margaret A.; Schoener, Cody; Peppas, Nicholas A.

2011-01-01

Hydrogels have been instrumental in the development of polymeric systems for controlled release of therapeutic agents. These materials are attractive for transmucosal and intracellular drug delivery because of their facile synthesis, inherent biocompatibility, tunable physicochemical properties, and capacity to respond to various physiological stimuli. In this contribution, we outline a multifaceted hydrogel-based approach for expanding the range of therapeutics in oral formulations from classical small-molecule drugs to include proteins, chemotherapeutics, and nucleic acids. Through judicious materials selection and careful design of copolymer composition and molecular architecture, we can engineer systems capable of responding to distinct physiological cues, with tunable physicochemical properties that are optimized to load, protect, and deliver valuable macromolecular payloads to their intended site of action. These hydrogel carriers, including complexation hydrogels, tethered hydrogels, interpenetrating networks, nanoscale hydrogels, and hydrogels with decorated structures are investigated for their ability respond to changes in pH, to load and release insulin and fluorescein, and remain non-toxic to Caco-2 cells. Our results suggest these novel hydrogel networks have great potential for controlled delivery of proteins, chemotherapeutics, and nucleic acids. PMID:21699934

Programmable and Bidirectional Bending of Soft Actuators Based on Janus Structure with Sticky Tough PAA-Clay Hydrogel.

PubMed

Zhao, Lei; Huang, Jiahe; Zhang, Yuancheng; Wang, Tao; Sun, Weixiang; Tong, Zhen

2017-04-05

Facile preparation, rapid actuating, and versatile actions are great challenges in exploring new kinds of hydrogel actuators. In this paper, we presented a facile sticking method to prepare Janus bilayer and multilayer hydrogel actuators that benefited from a special tough and adhesive PAA-clay hydrogel. Combining physical and chemical cross-linking reagents, we endowed the PAA gel with both toughness and adhesion. This PAA gel was reinforced by further cross-linking with Fe 3+ . These two hydrogels with different cross-linking densities exhibited different swelling capabilities and moduli in the media manipulated by pH and ionic strength, thus acting as promising candidates for soft actuators. On the basis of these gels, we designed hydrogel actuators of rapid response in several minutes and precisely controlled actuating direction by sticking two hydrogel layers together. Elaborate soft actuators such as bidirectional bending flytrap, gel hand with grasp, open, and gesturing actions as well as word-writing actuator were prepared. This method could be generalized by using other stimuli-responsive hydrogels combined with the adhesive PAA gel, which would open a new way to programmable and versatile soft actuators.

Bromelain Loading and Release from a Hydrogel Formulated Using Alginate and Arabic Gum.

PubMed

Ataide, Janaína Artem; Cefali, Letícia Caramori; Rebelo, Marcia de Araujo; Spir, Lívia Genovez; Tambourgi, Elias Basile; Jozala, Angela Faustino; Chaud, Marco Vinícius; Silveira, Edgar; Gu, Xiaochen; Gava Mazzola, Priscila

2017-07-01

An ideal wound dressing ensures a moist environment around the wound area and absorbs exudates from the wound surface. Topical application of bromelain to incised wounds has been shown to reprogram the wound microenvironment to promote effective tissue repair. Combining the characteristics of hydrogels and bromelain is therefore of great interest. Herein, we describe the development of a hydrogel, formulated using alginate and Arabic gum, for bromelain loading and release. The hydrogel formulation was evaluated using response surface methodology, considering the pH value and the concentration of alginate and Arabic gum. Bromelain loading and release were evaluated based on passive diffusion. Differential scanning calorimetry and Fourier transform infrared spectroscopy were performed to confirm bromelain immobilization in the hydrogel. The final hydrogel formulation had a swelling ratio of 227 % and incorporated 19 % of bromelain from a bromelain solution. Bromelain immobilization in the hydrogel was the result of hydrogen bond formation and was optimal at 4 °C after 4 h of contact. This evidence suggests that bromelain entrapment into a hydrogel is a promising strategy for the development of wound dressings that support the debridement of burns and wounds. Georg Thieme Verlag KG Stuttgart · New York.

Poly(N-isopropylacrylamide) hydrogel-based shape-adjustable polyimide films triggered by near-human-body temperature.

PubMed

Huanqing Cui; Xuemin Du; Juan Wang; Tianhong Tang; Tianzhun Wu

2016-08-01

Hydrogel-based shape-adjustable films were successfully fabricated via grafting poly(N-isopropylacrylamide) (PNIPAM) onto one side of polyimide (PI) films. The prepared PI-g-PNIPAM films exhibited rapid, reversible, and repeatable bending/unbending property by heating to near-human-body temperature (37 °C) or cooling to 25 °C. The excellent property of PI-g-PNIPAM films resulted from a lower critical solution temperature (LCST) of PNIPAM at about 32 °C. Varying the thickness of PNIPAM hydrogel layer regulated the thermo-responsive shape bending degree and response speed of PI-g-PNIPAM films. The thermo-induced shrinkage of hydrogel layers can tune the curvature of PI films, which have potential applications in the field of wearable and implantable devices.

Free radical scavenging injectable hydrogels for regenerative therapy.

PubMed

Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2017-02-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Controlled release of paclitaxel from a self-assembling peptide hydrogel formed in situ and antitumor study in vitro

PubMed Central

Liu, Jingping; Zhang, Lanlan; Yang, Zehong; Zhao, Xiaojun

2011-01-01

Background A nanoscale injectable in situ-forming hydrogel drug delivery system was developed in this study. The system was based on a self-assembling peptide RADA16 solution, which can spontaneously form a hydrogel rapidly under physiological conditions. We used the RADA16 hydrogel for the controlled release of paclitaxel (PTX), a hydrophobic antitumor drug. Methods The RADA16-PTX suspension was prepared simply by magnetic stirring, followed by atomic force microscopy, circular dichroism analysis, dynamic light scattering, rheological analysis, an in vitro release assay, and a cell viability test. Results The results indicated that RADA16 and PTX can interact with each other and that the amphiphilic peptide was able to stabilize hydrophobic drugs in aqueous solution. The particle size of PTX was markedly decreased in the RADA16 solution compared with its size in water. The RADA16-PTX suspension could form a hydrogel in culture medium, and the elasticity of the hydrogel showed a positive correlation with peptide concentration. In vitro release measurements indicated that hydrogels with a higher peptide concentration had a longer half-release time. The RADA16-PTX hydrogel could effectively inhibit the growth of the breast cancer cell line, MDA-MB-435S, in vitro, and hydrogels with higher peptide concentrations were more effective at inhibiting tumor cell proliferation. The RADA16-PTX hydrogel was effective at controlling the release of PTX and inhibiting tumor cell growth in vitro. Conclusion Self-assembling peptide hydrogels may work well as a system for drug delivery. PMID:22114478

Design of multimodal degradable hydrogels for controlled therapeutic delivery

NASA Astrophysics Data System (ADS)

Kharkar, Prathamesh Madhav

Hydrogels are of growing interest for the delivery of therapeutics to specific sites in the body. For localized drug delivery, hydrophilic polymeric precursors often are laden with bioactive moieties and then directly injected to the site of interest for in situ gel formation. The release of physically entrapped cargo is dictated by Fickian diffusion, degradation of the drug carrier, or a combination of both. The goal of this work was to design and characterize degradable hydrogel formulations that are responsive to multiple biologically relevant stimuli for degradation-mediated delivery of cargo molecules such as therapeutic proteins, growth factors, and immunomodulatory agents. We began by demonstrating the use of cleavable click linkages formed by Michael-type addition reactions in conjunction with hydrolytically cleavable functionalities for the degradation of injectable hydrogels by endogenous stimuli for controlled protein release. Specifically, the reaction between maleimides and thiols was utilized for hydrogel formation, where thiol selection dictates the degradability of the resulting linkage under thiol-rich reducing conditions. Relevant microenvironments where degradation would occur in vivo include those rich in glutathione (GSH), a tripeptide that is found at elevated concentrations in carcinoma tissues. Degradation of the hydrogels was monitored with rheometry and volumetric swelling measurements. Arylthiol-based thioether succinimide linkages underwent degradation via click cleavage and thiol exchange reaction in the presence of GSH and via ester hydrolysis, whereas alkylthiol-based thioether succinimide linkages only undergo degradation by only ester hydrolysis. The resulting control over the degradation rate within a reducing microenvironment resulted in 2.5 fold differences in the release profile of the model protein, a fluorescently-labeled bovine serum albumin, from dually degradable hydrogels compared to non-degradable hydrogels, where the thiol exchange reaction facilitated rapid and responsive protein release in the presence of GSH. A photolabile o-nitrobenzyl ether group (o-NB) was subsequently incorporated within the PEG-based, gel-forming monomers to demonstrate cargo release triggered by exogenous stimuli for patient-specific therapies. Upon the application of cytocompatible doses of light, the photolabile o-NB linkage underwent irreversible cleavage yielding ketone and carboxylic acid-based cleavage products. Hydrogel degradation kinetics was characterized in response to externally applied cytocompatible light or GSH in aqueous microenvironments. By incorporating a photodegradable o-nitrobenzyl ether group, a thiol-sensitive succinimide thioether linkage, and ester linkages within the hydrogels, we demonstrated unique control over degradation via surface erosion or bulk degradation mechanisms, respectively, with degradation rate constants ranging from 10-1 min-1 to 10-4 min-1. As a proof of concept, the controlled release of nanobeads from the hydrogel was demonstrated in a preprogrammed and stimuli-responsive fashion. The multimodal degradable hydrogels were then investigated for the local controlled release of small molecular weight proteins, which are of interest for regulating various cellular functions and fates in vivo. Low molecular weight heparin, a highly sulfated polysaccharide was incorporated within the hydrogel network by Michael-type reaction due to its affinity with biologics such as growth factors and immunomodulatory proteins. Incorporation of reduction-sensitive linkages resulted in 2.3 fold differences in the release profile of fibroblast growth factor-2 (FGF-2) in the presence of GSH compared to non-reducing microenvironment. Bioactivity of released FGF-2 was comparable to pristine FGF-2, indicating the ability of the hydrogel to retain bioactivity of cargo molecules during encapsulation and release. Further, preliminary in vivo studies demonstrated control over hydrogel degradation by varying % degradable contents. Collectively, this research developed injectable hydrogels that are responsive to various endogenous and exogenous stimuli, establishing a platform for stimuli-responsive drug delivery carriers.

An injectable particle-hydrogel hybrid system for glucose-regulatory insulin delivery.

PubMed

Zhao, Fuli; Wu, Di; Yao, Dan; Guo, Ruiwei; Wang, Weiwei; Dong, Anjie; Kong, Deling; Zhang, Jianhua

2017-12-01

Long-term and daily subcutaneous injections of insulin for the treatment of insulin-dependent diabetic patients often lead to poor patient compliance and undesired complications. Phenylboronic acid (PBA)-based polymeric hydrogels have been widely considered as one of the most promising insulin delivery system to replace the frequent insulin injections. However, their applications are limited by clinically irrelevant glucose-responsive range, slow response rate, low tissue-adhesiveness and poor biodegradability, undesirable leakage at normoglycemic state. Herein, we report a novel implantable insulin hydrogel for glucose-regulated delivery of insulin based on a unique particle-hydrogel hybrid platform featuring fast glucose responsiveness at physiological pH, shear-thinning behavior for injection, tissue-adhesive function for long-lasting adherence, and full biodegradability for safe use. The system was thoroughly characterized both in vitro and in vivo and was demonstrated to hold these unique functions. Using streptozotocin-induced diabetic mice as a model, it was shown that a single subcutaneous injection of the insulin-loaded particle-hydrogel formulation led to quasi-steady-state blood glucose levels within the normal range for about two weeks. In addition, the preparation of the formulation only involved simple mixing and self-assembling processes, and thus it had great scalability and reproducibility for practical use. The highly feasible preparation, excellent performance, inherent biocompatibility and biodegradability make this novel composite hydrogel promising platform for diabetes therapy. Phenylboronic acid (PBA)-based polymeric hydrogels have been widely considered as one of the most promising insulin delivery system to replace the frequent insulin injections. However, these hydrogels, mostly based on a variety of PBA-containing acrylamide monomers, are still far from clinical reality. Building upon a unique particle-hydrogel hybrid platform, herein we report a novel implantable insulin storage and delivery system with multifunctionalities including fast glucose-sensitiveness at physiological pH, shear-thinning behavior for injection, tissue-adhesive function for long-lasting adherence, biodegradable materials for safe use and well-controlled insulin release. These unique functions were demonstrated through research both in vitro and in vivo. In addition, the preparation of the formulation was simple, and thus it had great scalability and reproducibility for practical use. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

3D patterned substrates for bioartificial blood vessels - The effect of hydrogels on aligned cells on a biomaterial surface.

PubMed

Zhao, Xinxin; Irvine, Scott Alexander; Agrawal, Animesh; Cao, Ye; Lim, Pei Qi; Tan, Si Ying; Venkatraman, Subbu S

2015-10-01

The optimal bio-artificial blood vessel construct is one that has a compliant tubular core with circumferentially aligned smooth muscle cells (SMCs). Obtaining this well-aligned pattern of SMCs on a scaffold is highly beneficial as this cellular orientation preserves the SMC contractile phenotype. We used 3D patterning to create channels on a polycaprolactone (PCL) scaffold; SMCs were then found to be aligned within the microchannels. To preserve this alignment, and to provide a protective coating that could further incorporate cells, we evaluated the use of two hydrogels, one based on poly(ethylene glycol) diacrylate (PEGDA) and the other based on gelatin. Hydrogels were either physically coated on the PCL surfaces or covalently linked via suitable surface modification of PCL. For covalent immobilization of PEGDA hydrogel, alkene groups were introduced on PCL, while for gelatin covalent linkage, serum proteins were introduced. It is, however, crucial that the hydrogel coating does not disrupt the cellular patterning and distribution. We show in this work that both the process of coating as well as the nature of the coating are critical to preservation of the aligned SMCs. The covalent coating methods involving the crosslinking of hydrogels with the surface of PCL films promoted hydrogel retention time on the film as compared with physical deposition. Furthermore, subsequent hydrogel degradation is affected by the components of the cell culture medium, hinting at a possible route to in vivo biodegradation. Surface features control cellular orientation and subsequently influence their functionality, a useful effect for cellularized biomedical devices. Such devices also can benefit from protective and cell friendly hydrogel coatings. However, literature is lacking on the fate of cells that have endured hydrogel coating whilst orientated on a biomaterial surface. In particular, elucidation of the cells ability to remain adherent and orientated post hydrogel addition. Coating requires two procedures that may be deleterious to the orientated cells: the surface pretreatment for gel binding and the hydrogel crosslinking reaction. We compare transglutaminase gelatin crosslinking and UV initiated PEGDA crosslinking, coated onto smooth muscle cells orientated on patterned PCL surfaces. This original study will be of considerable use to the wider biomaterials community. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cell-laden hydrogels for osteochondral and cartilage tissue engineering.

PubMed

Yang, Jingzhou; Zhang, Yu Shrike; Yue, Kan; Khademhosseini, Ali

2017-07-15

Despite tremendous advances in the field of regenerative medicine, it still remains challenging to repair the osteochondral interface and full-thickness articular cartilage defects. This inefficiency largely originates from the lack of appropriate tissue-engineered artificial matrices that can replace the damaged regions and promote tissue regeneration. Hydrogels are emerging as a promising class of biomaterials for both soft and hard tissue regeneration. Many critical properties of hydrogels, such as mechanical stiffness, elasticity, water content, bioactivity, and degradation, can be rationally designed and conveniently tuned by proper selection of the material and chemistry. Particularly, advances in the development of cell-laden hydrogels have opened up new possibilities for cell therapy. In this article, we describe the problems encountered in this field and review recent progress in designing cell-hydrogel hybrid constructs for promoting the reestablishment of osteochondral/cartilage tissues. Our focus centers on the effects of hydrogel type, cell type, and growth factor delivery on achieving efficient chondrogenesis and osteogenesis. We give our perspective on developing next-generation matrices with improved physical and biological properties for osteochondral/cartilage tissue engineering. We also highlight recent advances in biomanufacturing technologies (e.g. molding, bioprinting, and assembly) for fabrication of hydrogel-based osteochondral and cartilage constructs with complex compositions and microarchitectures to mimic their native counterparts. Despite tremendous advances in the field of regenerative medicine, it still remains challenging to repair the osteochondral interface and full-thickness articular cartilage defects. This inefficiency largely originates from the lack of appropriate tissue-engineered biomaterials that replace the damaged regions and promote tissue regeneration. Cell-laden hydrogel systems have emerged as a promising tissue-engineering platform to address this issue. In this article, we describe the fundamental problems encountered in this field and review recent progress in designing cell-hydrogel constructs for promoting the reestablishment of osteochondral/cartilage tissues. Our focus centers on the effects of hydrogel composition, cell type, and growth factor delivery on achieving efficient chondrogenesis and osteogenesis. We give our perspective on developing next-generation hydrogel/inorganic particle/stem cell hybrid composites with improved physical and biological properties for osteochondral/cartilage tissue engineering. We also highlight recent advances in biomanufacturing and bioengineering technologies (e.g. 3D bioprinting) for fabrication of hydrogel-based osteochondral and cartilage constructs. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Thermo-responsive in-situ forming hydrogels as barriers to prevent post-operative peritendinous adhesion.

PubMed

Chou, Pang-Yun; Chen, Shih-Heng; Chen, Chih-Hao; Chen, Shih-Hsien; Fong, Yi Teng; Chen, Jyh-Ping

2017-11-01

In this study, we aimed to assess whether thermo-responsive in-situ forming hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) could prevent post-operative peritendinous adhesion. The clinical advantages of the thermo-responsive hydrogels are acting as barrier material to block penetration of fibroblasts, providing mobility and flexibility during application and enabling injection through a small opening to fill spaces of any shape after surgery. The thermo-responsiveness of hydrogels was determined to ensure their clinic uses. By grafting hydrophilic biopolymers chitosan (CS) and hyaluronic acid (HA) to PNIPAM, the copolymer hydrogels show enhanced water retention and lubrication, while reduced volume shrinkage during phase transition. In cell culture experiments, the thermo-responsive hydrogel has good biocompatibility and reduces fibroblast penetration. In animal experiments, the effectiveness of preventing post-operative peritendinous adhesion was studied in a rabbit deep flexor tendon model. From gross examination, histology, bending angles of joints, tendon gliding excursion and pull-out force, HA-CS-PNIPAM (HACPN) was confirmed to be the best barrier material to prevent post-operative peritendinous adhesion compared to PNIPAM and CS-PNIPAM (CPN) hydrogels and a commercial barrier film Seprafilm®. There was no significant difference in the breaking strength of HACPN-treated tendons and spontaneously healed ones, indicating HACPN hydrogel application did not interfere with normal tendon healing. We conclude that HACPN hydrogel can provide the best functional outcomes to significantly prevent post-operative tendon adhesion in vivo. We prepared thermo-responsive in-situ forming hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) to prevent post-operative peritendinous adhesion. The injectable barrier hydrogel could have better anti-adhesive properties than current commercial products by acting as barrier material to block penetration of fibroblasts, providing mobility and flexibility during application and enabling injection through a small opening to fill spaces of any shape after surgery. The effectiveness of preventing post-operative peritendinous adhesion was studied in a rabbit deep flexor tendon model. From gross examination, histology, bending angles of joints, tendon gliding excursion and pull-out force, HA-CS-PNIPAM (HACPN) was confirmed to be the best barrier material to prevent post-operative peritendinous adhesion compared to PNIPAM and CS-PNIPAM (CPN) hydrogels and a commercial barrier film Seprafilm®. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hydrogel-laden paper scaffold system for origami-based tissue engineering

PubMed Central

Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S.

2015-01-01

In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca2+. This procedure ensures the formation of alginate hydrogel on the paper due to Ca2+ diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs. PMID:26621717

Culture of preantral follicles in poly(ethylene) glycol-based, three-dimensional hydrogel: a relationship between swelling ratio and follicular developments

PubMed Central

Ahn, Jong Il; Kim, Gil Ah; Kwon, Hyo Suk; Ahn, Ji Yeon; Hubbell, Jeffrey A; Song, Yong Sang; Lee, Seung Tae; Lim, Jeong Mook

2015-01-01

This study was undertaken to examine how the softness of poly(ethylene) glycol (PEG)-based hydrogels, creating a three-dimensional (3D) microenvironment, influences the in vitro growth of mouse ovarian follicles. Early secondary, preantral follicles of 2 week-old mice were cultured in a crosslinked four-arm PEG hydrogel. The hydrogel swelling ratio, which relates to softness, was modified within the range 25.7–15.5 by increasing the reactive PEG concentration in the precursor solution from 5% to 15% w/v, but it did not influence follicular growth to form the pseudoantrum (60–80%; p = 0.76). Significant (p < 0.04) model effects, however, were detected in the maturation and developmental competence of the follicle-derived oocytes. A swelling ratio of > 21.4 yielded better oocyte maturation than other levels, while the highest competence to develop pronuclear and blastocyst formation was detected at 20.6. In conclusion, gel softness, as reflected in swelling ratio, was one of the essential factors for supporting folliculogenesis in vivo within a hydrogel-based, 3D microenvironment. © 2014 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd. PMID:24493269

Hydrogel-laden paper scaffold system for origami-based tissue engineering.

PubMed

Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S

2015-12-15

In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca(2+). This procedure ensures the formation of alginate hydrogel on the paper due to Ca(2+) diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs.

Mineral-Enhanced Polyacrylic Acid Hydrogel as an Oyster-Inspired Organic-Inorganic Hybrid Adhesive.

PubMed

Li, Ang; Jia, Yunfei; Sun, Shengtong; Xu, Yisheng; Minsky, Burcu Baykal; Stuart, M A Cohen; Cölfen, Helmut; von Klitzing, Regine; Guo, Xuhong

2018-03-28

Underwater adhesion is crucial to many marine life forms living a sedentary lifestyle. Amongst them, mussel adhesion has been mostly studied, which inspires numerous investigations of 3,4-dihydroxyphenylalanine (DOPA)-based organic adhesives. In contrast, reef-building oysters represent another important "inorganic" strategy of marine molluscs for adhesion by generating biomineralized organic-inorganic adhesives, which is still rarely studied and no synthetic analogues have ever been reported so far. Here, a novel type of oyster-inspired organic-inorganic adhesive based on a biomineralized polyelectrolyte hydrogel is reported, which consists of polyacrylic acid physically cross-linked by very small amorphous calcium carbonate nanoparticles (<3 nm). The mineral-enhanced polyelectrolyte hydrogel adhesive is shown to be injectable, reusable, and optically clear upon curing in air. Moreover, comparable adhesion performance to DOPA-based adhesives is found for the hydrogel adhesive in both dry and wet conditions, which can even be further enhanced by introducing a small amount of second large cross-linker such as negatively charged nanoparticles. The present mineral hydrogel represents a new type of bio-inspired organic-inorganic adhesive that may find a variety of potential applications in adhesive chemistry.

RNA extraction from self-assembling peptide hydrogels to allow qPCR analysis of encapsulated cells.

PubMed

Burgess, Kyle A; Workman, Victoria L; Elsawy, Mohamed A; Miller, Aline F; Oceandy, Delvac; Saiani, Alberto

2018-01-01

Self-assembling peptide hydrogels offer a novel 3-dimensional platform for many applications in cell culture and tissue engineering but are not compatible with current methods of RNA isolation; owing to interactions between RNA and the biomaterial. This study investigates the use of two techniques based on two different basic extraction principles: solution-based extraction and direct solid-state binding of RNA respectively, to extract RNA from cells encapsulated in four β-sheet forming self-assembling peptide hydrogels with varying net positive charge. RNA-peptide fibril interactions, rather than RNA-peptide molecular complexing, were found to interfere with the extraction process resulting in low yields. A column-based approach relying on RNA-specific binding was shown to be more suited to extracting RNA with higher purity from these peptide hydrogels owing to its reliance on strong specific RNA binding interactions which compete directly with RNA-peptide fibril interactions. In order to reduce the amount of fibrils present and improve RNA yields a broad spectrum enzyme solution-pronase-was used to partially digest the hydrogels before RNA extraction. This pre-treatment was shown to significantly increase the yield of RNA extracted, allowing downstream RT-qPCR to be performed.

Gelatin-based Hydrogel Degradation and Tissue Interaction in vivo: Insights from Multimodal Preclinical Imaging in Immunocompetent Nude Mice.

PubMed

Tondera, Christoph; Hauser, Sandra; Krüger-Genge, Anne; Jung, Friedrich; Neffe, Axel T; Lendlein, Andreas; Klopfleisch, Robert; Steinbach, Jörg; Neuber, Christin; Pietzsch, Jens

2016-01-01

Hydrogels based on gelatin have evolved as promising multifunctional biomaterials. Gelatin is crosslinked with lysine diisocyanate ethyl ester (LDI) and the molar ratio of gelatin and LDI in the starting material mixture determines elastic properties of the resulting hydrogel. In order to investigate the clinical potential of these biopolymers, hydrogels with different ratios of gelatin and diisocyanate (3-fold (G10_LNCO3) and 8-fold (G10_LNCO8) molar excess of isocyanate groups) were subcutaneously implanted in mice (uni- or bilateral implantation). Degradation and biomaterial-tissue-interaction were investigated in vivo (MRI, optical imaging, PET) and ex vivo (autoradiography, histology, serum analysis). Multimodal imaging revealed that the number of covalent net points correlates well with degradation time, which allows for targeted modification of hydrogels based on properties of the tissue to be replaced. Importantly, the degradation time was also dependent on the number of implants per animal. Despite local mechanisms of tissue remodeling no adverse tissue responses could be observed neither locally nor systemically. Finally, this preclinical investigation in immunocompetent mice clearly demonstrated a complete restoration of the original healthy tissue.

Superporous hybrid hydrogels based on polyacrylamide and chitosan: Characterization and in vitro drug release

PubMed Central

Nagpal, Manju; Singh, Shailendra Kumar; Mishra, Dinanath

2013-01-01

Objective: Current research was aimed at the development of the drug delivery systems based on the superporous hydrogels (SPH) with the desired swelling and the mechanical properties. Materials and Methods: Superporous hydrogel composites (SPHCs) and superporous hybrid hydrogels (SPHHs) based on the chitosan and the polyacrylamide were synthesized using the gas blowing technique. The prepared hydrogels were evaluated for swelling studies, mechanical strength and scanning electron microscopy. The selected hydrogels were loaded with the drug (verapamil hydrochloride) by aqueous loading method. Drug integrity with in polymeric network was evaluated via fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-RD), differential scanning calorimetry (DSC), proton nuclear magnetic resonance (1HNMR) studies. In vitro drug release studies were carried out using the united state pharmacopoeial (USP) dissolution apparatus (type II). Results and Discussion: The mechanical strength was observed to be higher in SPH hybrids in comparison to that in SPHCs while no significant difference was observed in swelling behavior. In situ crosslinking of chitosan with glutaraldehyde (GA) may be responsible for high mechanical strength. The equilibrium swelling time was slight higher in SPHH than in SPHCs. The integrity of pores was maintained in ethanol treated hydrogels as observed in scanning electron micrographs. Whereas, freeze dried SPH samples showed non-uniform pores. No drug polymer interaction was observed as indicated by DSC, FTIR, X-RD and NMR studies. However, the crosslinking of chitosan with GA was clearly indicated by these studies. The in vitro drug release studies from SPH hybrids indicated initial fast release (65%) with in first 2 h and then sustained release at the end of 24 h (95%). The addition of hydroxypropyl methyl cellulose with drug; however, leads to a significant decrease in drug release (56% at the end of 24 h). Conclusion: Superporous hybrid hydrogels can be promising devices for the sustained delivery of drug candidates to the gastrointestinal region. PMID:24015380

A new injectable biphasic hydrogel based on partially hydrolyzed polyacrylamide and nano hydroxyapatite, crosslinked with chromium acetate, as scaffold for cartilage regeneration

NASA Astrophysics Data System (ADS)

Koushki, N.; Tavassoli, H.; Katbab, A. A.; Katbab, P.; Bonakdar, S.

2015-05-01

Polymer scaffolds are applied in the field of tissue engineering as three dimensional structures to organize cells and present stimuli to direct generation of a desired damaged tissue. In situ gelling scaffolds have attracted great attentions, as they are structurally similar to the extra cellular matrix (ECM). In the present work, attempts have been made to design and fabricate a new injectable and crosslinkable biphasic hydrogel based on partially hydrolyzed polyacrylamide (HPAM), chromium acetate as crosslink agent and nanocrystalline hydroxyapatite (nHAp) as reinforcing and bioactive agent for repair and regeneration of damaged cartilage. The distinct characteristic of HPAM is the presence of carboxylate anion groups on its backbone which allows to engineer the structure of the hydrogel for the desired bioactivity with appropriate cells differentiation towards both soft and hard (bone) tissues. The synthesized hydrogel exhibited bifunctional behavior which was derived by its biphasic structure in which one phase was loaded with nano hydroxyapatite to provide integration capability by subchondral bones and fix the hydrogel at cartilage defect without a need for suturing. The other phase differentiates the rabbit adipogenic mesenchymal stem cells (MSCs) towards soft tissue. Rheomechanical spectrometry (RMS) was employed to study the kinetic of the gelation including induction time and rate, as well as to measure the ultimate elastic modulus of the optimum crosslinked hydrogel. Surface tension measurement was also performed to tailor the surface characteristics of the gels. In vitro culturing of the cells inside the crosslinked hydrogel revealed high viability and high differentiation of the encapsulated rabbit stem cells, providing that the chromium acetate level was kept below 0.2 wt%. Based on the obtained results, the designed and fabricated biphasic hydrogel exhibited high potential as carrier for the stem cells for cartilage tissue engineering application with excellent injectability.

Ultrasound stimulated release of mimosa medicine from cellulose hydrogel matrix.

PubMed

Jiang, Huixin; Tovar-Carrillo, Karla; Kobayashi, Takaomi

2016-09-01

Ultrasound (US) drug release system using cellulose based hydrogel films was developed as triggered to mimosa. Here, the mimosa, a fascinating drug to cure injured skin, was employed as the loading drug in cellulose hydrogel films prepared with phase inversion method. The mimosa hydrogels were fabricated from dimethylacetamide (DMAc)/LiCl solution in the presence of mimosa, when the solution was exposed to ethanol vapor. The US triggered release of the mimosa from the hydrogel matrix was carried out under following conditions of US powers (0-30W) and frequencies (23, 43 and 96kHz) for different mimosa hydrogel matrix from 0.5wt% to 2wt% cellulose solution. To release the drug by US trigger from the matrix, the better medicine release was observed in the matrix prepared from the 0.5wt% cellulose solution when the 43kHz US was exposed to the aqueous solution with the hydrogel matrix. The release efficiency increased with the increase of the US power from 5 to 30W at 43kHz. Viscoelasticity of the hydrogel matrix showed that the hydrogel became somewhat rigid after the US exposure. FT-IR analysis of the mimosa hydrogel matrixes showed that during the US exposure, hydrogen bonds in the structure of mimosa-water and mimosa-cellulose were broken. This suggested that the enhancement of the mimosa release was caused by the US exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

In vivo biofunctional evaluation of hydrogels for disc regeneration.

PubMed

Reitmaier, Sandra; Kreja, Ludwika; Gruchenberg, Katharina; Kanter, Britta; Silva-Correia, Joana; Oliveira, Joaquim Miguel; Reis, Rui Luís; Perugini, Valeria; Santin, Matteo; Ignatius, Anita; Wilke, Hans-Joachim

2014-01-01

Regenerative strategies aim to restore the original biofunctionality of the intervertebral disc. Different biomaterials are available, which might support disc regeneration. In the present study, the prospects of success of two hydrogels functionalized with anti-angiogenic peptides and seeded with bone marrow derived mononuclear cells (BMC), respectively, were investigated in an ovine nucleotomy model. In a one-step procedure iliac crest aspirates were harvested and, subsequently, separated BMC were seeded on hydrogels and implanted into the ovine disc. For the cell-seeded approach a hyaluronic acid-based hydrogel was used. The anti-angiogenic potential of newly developed VEGF-blockers was investigated on ionically crosslinked metacrylated gellan gum hydrogels. Untreated discs served as nucleotomy controls. 24 adult merino sheep were used. After 6 weeks histological, after 12 weeks histological and biomechanical analyses were conducted. Biomechanical tests revealed no differences between any of the implanted and nucleotomized discs. All implanted discs significantly degenerated compared to intact discs. In contrast, there was no marked difference between implanted and nucleotomized discs. In tendency, albeit not significant, degeneration score and disc height index deteriorated for all but not for the cell-seeded hydrogels from 6 to 12 weeks. Cell-seeded hydrogels slightly decelerated degeneration. None of the hydrogel configurations was able to regenerate biofunctionality of the intervertebral disc. This might presumably be caused by hydrogel extrusion. Great importance should be given to the development of annulus sealants, which effectively exploit the potential of (cell-seeded) hydrogels for biological disc regeneration and restoration of intervertebral disc functioning.

Thermo-responsive methylcellulose hydrogels as temporary substrate for cell sheet biofabrication.

PubMed

Altomare, Lina; Cochis, Andrea; Carletta, Andrea; Rimondini, Lia; Farè, Silvia

2016-05-01

Methylcellulose (MC), a water-soluble polymer derived from cellulose, was investigated as a possible temporary substrate having thermo-responsive properties favorable for cell culturing. MC-based hydrogels were prepared by a dispersion technique, mixing MC powder (2, 4, 6, 8, 10, 12 % w/v) with selected salts (sodium sulphate, Na2SO4), sodium phosphate, calcium chloride, or phosphate buffered saline, to evaluate the influence of different compositions on the thermo-responsive behavior. The inversion test was used to determine the gelation temperatures of the different hydrogel compositions; thermo-mechanical properties and thermo-reversibility of the MC hydrogels were investigated by rheological analysis. Gelation temperatures and rheological behavior depended on the MC concentration and type and concentration of salt used in hydrogel preparation. In vitro cytotoxicity tests, performed using L929 mouse fibroblasts, showed no toxic release from all the tested hydrogels. Among the investigated compositions, the hydrogel composed of 8 % w/v MC with 0.05 M Na2SO4 had a thermo-reversibility temperature at 37 °C. For that reason, this formulation was thus considered to verify the possibility of inducing in vitro spontaneous detachment of cells previously seeded on the hydrogel surface. A continuous cell layer (cell sheet) was allowed to grow and then detached from the hydrogel surface without the use of enzymes, thanks to the thermo-responsive behavior of the MC hydrogel. Immunofluorescence observation confirmed that the detached cell sheet was composed of closely interacting cells.

Review of collagen I hydrogels for bioengineered tissue microenvironments: characterization of mechanics, structure, and transport.

PubMed

Antoine, Elizabeth E; Vlachos, Pavlos P; Rylander, Marissa Nichole

2014-12-01

Type I collagen hydrogels have been used successfully as three-dimensional substrates for cell culture and have shown promise as scaffolds for engineered tissues and tumors. A critical step in the development of collagen hydrogels as viable tissue mimics is quantitative characterization of hydrogel properties and their correlation with fabrication parameters, which enables hydrogels to be tuned to match specific tissues or fulfill engineering requirements. A significant body of work has been devoted to characterization of collagen I hydrogels; however, due to the breadth of materials and techniques used for characterization, published data are often disjoint and hence their utility to the community is reduced. This review aims to determine the parameter space covered by existing data and identify key gaps in the literature so that future characterization and use of collagen I hydrogels for research can be most efficiently conducted. This review is divided into three sections: (1) relevant fabrication parameters are introduced and several of the most popular methods of controlling and regulating them are described, (2) hydrogel properties most relevant for tissue engineering are presented and discussed along with their characterization techniques, (3) the state of collagen I hydrogel characterization is recapitulated and future directions are proposed. Ultimately, this review can serve as a resource for selection of fabrication parameters and material characterization methodologies in order to increase the usefulness of future collagen-hydrogel-based characterization studies and tissue engineering experiments.

The dynamic magnetoviscoelastic properties of biomineralized (Fe3O4) PVP-CMC hydrogel

NASA Astrophysics Data System (ADS)

Ray, Ayan; Saha, Nabanita; Saha, Petr

2017-05-01

The Polyvinylpyrrolidone (PVP) and carboxymethylcellulose (CMC) based polymer matrix was used as a template for the preparation of magnetic hydrogel. This freshly prepared PVP-CMC hydrogel template was successfully mineralized by in situ synthesis of magnetic nanoparticles (Fe3O4) via chemical co-precipitation reaction using liquid diffusion method. The present study emphasizes on the rheological behavior of non-mineralized and mineralized PVP-CMC hydrogels. Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD) pattern, Fourier transform infrared spectroscopy (FT-TR), Vibrating sample magnetometer (VSM) and dynamic magneto rheometer were used to study the morphological, physical, chemical and magnetic properties of nanoparticle (Fe3O4) filled PVP-CMC hydrogel respectively in order to monitor how Fe3O4 magnetic nanoparticles affects the mechanical properties of the hydrogel network. The storage (G') and loss (G") moduli with a complex viscosity of the system was measured using a parallel plate rheometer. Frequency and amplitude sweep with temperature variation was performed to determine the frequency and amplitude dependent magneto viscoelastic moduli for both hydrogel samples. A strong shear thinning effect was observed in both (non-mineralized and mineralized) PVP-CMC hydrogels, which confirm that Fe3O4 filled magnetic hydrogels, are pseudoplastic in nature. This Fe3O4 filled PVP-CMC hydrogel can be considered as stimuli-responsive soft matter that may be used as an actuator in medical devices.

Review of Collagen I Hydrogels for Bioengineered Tissue Microenvironments: Characterization of Mechanics, Structure, and Transport

PubMed Central

Vlachos, Pavlos P.; Rylander, Marissa Nichole

2014-01-01

Type I collagen hydrogels have been used successfully as three-dimensional substrates for cell culture and have shown promise as scaffolds for engineered tissues and tumors. A critical step in the development of collagen hydrogels as viable tissue mimics is quantitative characterization of hydrogel properties and their correlation with fabrication parameters, which enables hydrogels to be tuned to match specific tissues or fulfill engineering requirements. A significant body of work has been devoted to characterization of collagen I hydrogels; however, due to the breadth of materials and techniques used for characterization, published data are often disjoint and hence their utility to the community is reduced. This review aims to determine the parameter space covered by existing data and identify key gaps in the literature so that future characterization and use of collagen I hydrogels for research can be most efficiently conducted. This review is divided into three sections: (1) relevant fabrication parameters are introduced and several of the most popular methods of controlling and regulating them are described, (2) hydrogel properties most relevant for tissue engineering are presented and discussed along with their characterization techniques, (3) the state of collagen I hydrogel characterization is recapitulated and future directions are proposed. Ultimately, this review can serve as a resource for selection of fabrication parameters and material characterization methodologies in order to increase the usefulness of future collagen-hydrogel-based characterization studies and tissue engineering experiments. PMID:24923709

2-hydroxyethyl metahcrylate/gelatin based superporous hydrogels for tissue regeneration

NASA Astrophysics Data System (ADS)

Tomić, Simonida Lj.; Babić, Marija M.; Vuković, Jovana S.; Perišić, Marija D.; Filipović, Vuk V.; Davidović, Sladjana Z.; Filipović, Jovanka M.

2016-05-01

In this study, superporous hydrogels were synthesized by free radical polymerization of 2-hydroxyethyl methacrylate without and in the presence of gelatin. Highly porous hydrogel structures were obtained by two different techniques: using a gas blowing agent, sodium bicarbonate, and a cryogenic treatment followed by freeze-drying. After the gel synthesis, gelatin molecules were covalently immobilised onto PHEMA via glytaraldehyde activation. All samples were characterized for morphological, mechanical, swelling and antibacterial properties. The results obtained show that samples with gelatin show better properties in comparison with PHEMA samples, which make these materials highly attractive for developing hydrogel scaffolds for tissue regeneration.

Bioactive factor delivery strategies from engineered polymer hydrogels for therapeutic medicine

PubMed Central

Nguyen, Minh Khanh; Alsberg, Eben

2014-01-01

Polymer hydrogels have been widely explored as therapeutic delivery matrices because of their ability to present sustained, localized and controlled release of bioactive factors. Bioactive factor delivery from injectable biopolymer hydrogels provides a versatile approach to treat a wide variety of diseases, to direct cell function and to enhance tissue regeneration. The innovative development and modification of both natural-(e.g., alginate (ALG), chitosan, hyaluronic acid (HA), gelatin, heparin (HEP), etc.) and synthetic-(e.g., polyesters, polyethyleneimine (PEI), etc.) based polymers has resulted in a variety of approaches to design drug delivery hydrogel systems from which loaded therapeutics are released. This review presents the state-of-the-art in a wide range of hydrogels that are formed though self-assembly of polymers and peptides, chemical crosslinking, ionic crosslinking and biomolecule recognition. Hydrogel design for bioactive factor delivery is the focus of the first section. The second section then thoroughly discusses release strategies of payloads from hydrogels for therapeutic medicine, such as physical incorporation, covalent tethering, affinity interactions, on demand release and/or use of hybrid polymer scaffolds, with an emphasis on the last 5 years. PMID:25242831

Alginate-polyester comacromer based hydrogels as physiochemically and biologically favorable entities for cardiac tissue engineering.

PubMed

Thankam, Finosh G; Muthu, Jayabalan

2015-11-01

The physiochemical and biological responses of tissue engineering hydrogels are crucial in determining their desired performance. A hybrid comacromer was synthesized by copolymerizing alginate and poly(mannitol fumarate-co-sebacate) (pFMSA). Three bimodal hydrogels pFMSA-AA, pFMSA-MA and pFMSA-NMBA were synthesized by crosslinking with Ca(2+) and vinyl monomers acrylic acid (AA), methacrylic acid (MA) and N,N'-methylene bisacrylamide (NMBA), respectively. Though all the hydrogels were cytocompatible and exhibited a normal cell cycle profile, pFMSA-AA exhibited superior physiochemical properties viz non-freezable water content (58.34%) and water absorption per unit mass (0.97 g water/g gel) and pore length (19.92±3.91 μm) in comparing with other two hydrogels. The increased non-freezable water content and water absorption of pFMSA-AA hydrogels greatly influenced its biological performance, which was evident from long-term viability assay and cell cycle proliferation. The physiochemical and biological favorability of pFMSA-AA hydrogels signifies its suitability for cardiac tissue engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

Skin-Inspired Multifunctional Autonomic-Intrinsic Conductive Self-Healing Hydrogels with Pressure Sensitivity, Stretchability, and 3D Printability.

PubMed

Darabi, Mohammad Ali; Khosrozadeh, Ali; Mbeleck, Rene; Liu, Yuqing; Chang, Qiang; Jiang, Junzi; Cai, Jun; Wang, Quan; Luo, Gaoxing; Xing, Malcolm

2017-08-01

The advent of conductive self-healing (CSH) hydrogels, a class of novel materials mimicking human skin, may change the trajectory of the industrial process because of their potential applications in soft robots, biomimetic prostheses, and health-monitoring systems. Here, the development of a mechanically and electrically self-healing hydrogel based on physically and chemically cross-linked networks is reported. The autonomous intrinsic self-healing of the hydrogel is attained through dynamic ionic interactions between carboxylic groups of poly(acrylic acid) and ferric ions. A covalent cross-linking is used to support the mechanical structure of the hydrogel. Establishing a fair balance between the chemical and physical cross-linking networks together with the conductive nanostructure of polypyrrole networks leads to a double network hydrogel with bulk conductivity, mechanical and electrical self-healing properties (100% mechanical recovery in 2 min), ultrastretchability (1500%), and pressure sensitivity. The practical potential of CSH hydrogels is further revealed by their application in human motion detection and their 3D-printing performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Glucose-specific poly(allylamine) hydrogels--a reassessment.

PubMed

Fazal, Furqan M; Hansen, David E

2007-01-01

Polymer hydrogels synthesized by crosslinking poly(allylamine hydrochloride) with (+/-)-epichlorohydrin in the presence of d-glucose-6-phosphate monobarium salt do not show imprinting on the molecular level. A series of hydrogels was prepared using the following five templates: d-glucose-6-phosphate monobarium salt, d-glucose, l-glucose, barium hydrogen phosphate (BaHPO(4)), and d-gluconamide; a hydrogel was also prepared in the absence of a template. For all six hydrogels, batch binding studies were conducted with d-glucose, l-glucose, d-fructose, and d-gluconamide. The extent of analyte sugar binding was determined using (1)H NMR. Each hydrogel shows approximately the same relative binding affinity for the different sugar derivatives, and none displays selectivity for either glucose enantiomer. The results of the binding studies correlate with the octanol-water partition coefficients of the sugars, indicative that differential solubilities in the bulk polymer account for the binding affinities observed. Thus, in contrast to templated hydrogels prepared using methacrylate- or acrylamide-based reagents, true imprinting does not occur in this novel, crosslinked-poly(allylamine hydrochloride) system.

Development of crosslinked methylcellulose hydrogels for soft tissue augmentation using an ammonium persulfate-ascorbic acid redox system.

PubMed

Gold, Gittel T; Varma, Devika M; Taub, Peter J; Nicoll, Steven B

2015-12-10

Hydrogels composed of methylcellulose are candidate materials for soft tissue reconstruction. Although photocrosslinked methylcellulose hydrogels have shown promise for such applications, gels crosslinked using reduction-oxidation (redox) initiators may be more clinically viable. In this study, methylcellulose modified with functional methacrylate groups was polymerized using an ammonium persulfate (APS)-ascorbic acid (AA) redox initiation system to produce injectable hydrogels with tunable properties. By varying macromer concentration from 2% to 4% (w/v), the equilibrium moduli of the hydrogels ranged from 1.47 ± 0.33 to 5.31 ± 0.71 kPa, on par with human adipose tissue. Gelation time was found to conform to the ISO standard for injectable materials. Cellulase treatment resulted in complete degradation of the hydrogels within 24h, providing a reversible corrective feature. Co-culture with human dermal fibroblasts confirmed the cytocompatibility of the gels based on DNA measurements and Live/Dead imaging. Taken together, this evidence indicates that APS-AA redox-polymerized methylcellulose hydrogels possess properties beneficial for use as soft tissue fillers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Injectable hyperbranched poly(β-amino ester) hydrogels with on-demand degradation profiles to match wound healing processes.

PubMed

Xu, Qian; Guo, Linru; A, Sigen; Gao, Yongsheng; Zhou, Dezhong; Greiser, Udo; Creagh-Flynn, Jack; Zhang, Hong; Dong, Yixiao; Cutlar, Lara; Wang, Fagang; Liu, Wenguang; Wang, Wei; Wang, Wenxin

2018-02-28

Adjusting biomaterial degradation profiles to match tissue regeneration is a challenging issue. Herein, biodegradable hyperbranched poly(β-amino ester)s (HP-PBAEs) were designed and synthesized via "A2 + B4" Michael addition polymerization, and displayed fast gelation with thiolated hyaluronic acid (HA-SH) via a "click" thiol-ene reaction. HP-PBAE/HA-SH hydrogels showed tunable degradation profiles both in vitro and in vivo using diamines with different alkyl chain lengths and poly(ethylene glycol) diacrylates with varied PEG spacers. The hydrogels with optimized degradation profiles encapsulating ADSCs were used as injectable hydrogels to treat two different types of humanized excisional wounds - acute wounds with faster healing rates and diabetic wounds with slower healing and neo-tissue formation. The fast-degrading hydrogel showed accelerated wound closure in acute wounds, while the slow-degrading hydrogel showed better wound healing for diabetic wounds. The results demonstrate that the new HP-PBAE-based hydrogel in combination with ADSCs can be used as a well-controlled biodegradable skin substitute, which demonstrates a promising approach in the treatment of various types of skin wounds.

Rheological study of in-situ crosslinkable hydrogels based on hyaluronanic acid, collagen and sericin.

PubMed

Vulpe, Raluca; Le Cerf, Didier; Dulong, Virginie; Popa, Marcel; Peptu, Catalina; Verestiuc, Liliana; Picton, Luc

2016-12-01

The elaboration of chemically crosslinked hydrogels based on collagen (C), hyaluronanic acid (HA) and sericin (S) with different polymer ratios was investigated by in-situ rheology. This reaction was performed via amide or ester bond reaction activated by carbodiimide, in pure water. Prior to molecule crosslinking, the rheological behaviour of the biopolymers (alone or in mixture) was characterized in a semi-dilute concentration regime. Both flow and dynamic measurements showed that uncrosslinked collagen alone appears to be rather elastic with yield stress properties, whereas uncrosslinked HA alone appears to be rather shear thinning and viscoelastic in agreement with entangled polymer behaviour. Sericin exhibited Newtonian low viscosity behaviour according to its very low molar mass. Before crosslinking, HA exhibited viscoelastic behaviour at concentrations above the critical entangled concentration (C*) in the mixtures, thus HA shows promise as a matrix for future crosslinked networks, whereas sericin did not significantly modify the rheology. During the reaction, followed by rheology, the kinetics were slower for pure HA systems compared with the mixtures (i.e., with added collagen and/or to a lesser extent sericin). At the same time, the final network of hydrogels (i.e., the elastic modulus) was more structured in the mixture based systems. This result is explained by ester bonds (the only possibility for pure HA systems), which are less favourable and reactive than amide bonds (possible with sericin and collagen). The presence of collagen in the HA matrix reinforced the hydrogel network. SEM studies confirmed the structure of the hydrogels, and in vitro degradability was globally consistent with the effect of the selected enzyme according to the hydrogel composition. All the elaborated hydrogels were non-cytotoxic in vitro. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-assembled three-dimensional reduced graphene oxide-based hydrogel for highly efficient and facile removal of pharmaceutical compounds from aqueous solution.

PubMed

Umbreen, Nadia; Sohni, Saima; Ahmad, Imtiaz; Khattak, Nimat Ullah; Gul, Kashif

2018-05-14

Herein, self-assembled three-dimensional reduced graphene oxide (RGO)-based hydrogels were synthesized and characterized in detail. A thorough investigation on the uptake of three widely used pharmaceutical drugs, viz. Naproxen (NPX), Ibuprofen (IBP) and Diclofenac (DFC) was carried out from aqueous solutions. To ensure the sustainability of developed hydrogel assembly, practically important parameters such as desorption, recyclability and applicability to real samples were also evaluated. Using the developed 3D hydrogels as adsorptive platforms, excellent decontamination for the above mentioned persistent pharmaceutical drugs was achieved in acidic pH with a removal efficiency in the range of 70-80%. These hydrogels showed fast adsorption kinetics and experimental findings were fitted to different kinetic models, such as pseudo-first order, pseudo-second order, intra-particle and the Elovich models in an attempt to better understand the adsorption kinetics. Furthermore, equilibrium adsorption data was fitted to the Langmuir and Freundlich models, where relatively higher R 2 values obtained in case of former one suggested that monolayer adsorption played an important part in drug uptake. Thermodynamic aspects were also studied and negative ΔG 0 values obtained indicated the spontaneous nature of adsorption process. The study was also extended to check practical utility of as-prepared hydrogels by spiking real aqueous samples with drug solution, where high % recoveries obtained for NPX, IBP and DFC were of particular importance with regard to prospective application in wastewater treatment systems. We advocate RGO-based hydrogels as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in wastewater purification. Copyright © 2018 Elsevier Inc. All rights reserved.

Effects of pore forming agents on chitosan-graft-poly(N-vinylpyrrolidone) hydrogel properties for use as a matrix for floating drug delivery

NASA Astrophysics Data System (ADS)

Budianto, E.; Al-Shidqi, M. F.; Cahyana, A. H.

2017-07-01

Eradicating H. pylori-based infection by using conventional oral dosage form of amoxicillin trihydrate finds difficulties to overcome rapid gastric retention time. Encapsulating amoxicillin trihydrate in floating drug delivery system may solve the problem. In this research, the floating drug delivery system of amoxicillin trihydrate encapsulated in floating chitosan-graft-poly(N-vinyl pyrrolidone) hydrogels containing CaCO3 and NaHCO3 as pore forming agents has been successfully prepared. Pore forming agents used was varied with the ratio of 10 to 25% pore forming agents to total mass of the used materials. The hydrogel were characterizedusing FTIR spectrophotometer and stereo microscope. As pore forming agents compositions increased, the porosity (%) and floating properties increased but followed by decrease in drug entrapment efficiency. Most of the floating hydrogels possessed floating ability longer than 180 min and the highest porosity was found in hydrogel containing 25% NaHCO3. Hydrogel containing CaCO3 showed sustained drug release profile than hydrogel containing NaHCO3. However, the optimum formulation was achieved at composition of 10% NaHCO3 with 57% of drug entrapped within the hydrogel and 43% drug released. The results of these studies show that NaHCO3 is an effective pore forming agents for chitosan-graft-poly(N-vinyl pyrrolidone) hydrogel preparation as compare to CaCO3.

Visible Light Crosslinking of Methacrylated Hyaluronan Hydrogels for Injectable Tissue Repair

PubMed Central

Fenn, Spencer L.; Oldinski, Rachael A.

2015-01-01

Tissue engineering hydrogels are primarily cured in situ using ultraviolet (UV) radiation which limits the use of hydrogels as drug or cell carriers. Visible green light activated crosslinking systems are presented as a safe alternative to UV photocrosslinked hydrogels, without compromising material properties such as viscosity and stiffness. The objective of this study was to fabricate and characterize photocrosslinked hydrogels with well-regulated gelation kinetics and mechanical properties for the repair or replacement of soft tissue. An anhydrous methacrylation of hyaluronan (HA) was performed to control the degree of modification (DOM) of HA, verified by 1H-NMR spectroscopy. UV activated crosslinking was compared to visible green light activated crosslinking. While the different photocrosslinking techniques resulted in varied crosslinking times, comparable mechanical properties of UV and green light activated crosslinked hydrogels were achieved using each photocrosslinking method by adjusting time of light exposure. Methacrylated HA (HA-MA) hydrogels of varying molecular weight, DOM and concentration exhibited compressive moduli ranging from 1 kPa to 116 kPa, for UV crosslinking, and 3 kPa to 146 kPa, for green light crosslinking. HA-MA molecular weight and concentration were found to significantly influence moduli values. HA-MA hydrogels did not exhibit any significant cytotoxic affects towards human mesenchymal stem cells. Green light activated crosslinking systems are presented as a viable method to form natural-based hydrogels in situ. PMID:26097172

Towards a quantitative understanding of oxygen tension and cell density evolution in fibrin hydrogels.

PubMed

Demol, Jan; Lambrechts, Dennis; Geris, Liesbet; Schrooten, Jan; Van Oosterwyck, Hans

2011-01-01

The in vitro culture of hydrogel-based constructs above a critical size is accompanied by problems of unequal cell distribution when diffusion is the primary mode of oxygen transfer. In this study, an experimentally-informed mathematical model was developed to relate cell proliferation and death inside fibrin hydrogels to the local oxygen tension in a quantitative manner. The predictive capacity of the resulting model was tested by comparing its outcomes to the density, distribution and viability of human periosteum derived cells (hPDCs) that were cultured inside fibrin hydrogels in vitro. The model was able to reproduce important experimental findings, such as the formation of a multilayered cell sheet at the hydrogel periphery and the occurrence of a cell density gradient throughout the hydrogel. In addition, the model demonstrated that cell culture in fibrin hydrogels can lead to complete anoxia in the centre of the hydrogel for realistic values of oxygen diffusion and consumption. A sensitivity analysis also identified these two parameters, together with the proliferation parameters of the encapsulated cells, as the governing parameters for the occurrence of anoxia. In conclusion, this study indicates that mathematical models can help to better understand oxygen transport limitations and its influence on cell behaviour during the in vitro culture of cell-seeded hydrogels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Adenosine triphosphate diffusion through poly(ethylene glycol) diacrylate hydrogels can be tuned by cross-link density as measured by PFG-NMR

NASA Astrophysics Data System (ADS)

Majer, Günter; Southan, Alexander

2017-06-01

The diffusion of small molecules through hydrogels is of great importance for many applications. Especially in biological contexts, the diffusion of nutrients through hydrogel networks defines whether cells can survive inside the hydrogel or not. In this contribution, hydrogels based on poly(ethylene glycol) diacrylate with mesh sizes ranging from ξ = 1.1 to 12.9 nm are prepared using polymers with number-average molecular weights between Mn = 700 and 8000 g/mol. Precise measurements of diffusion coefficients D of adenosine triphosphate (ATP), an important energy carrier in biological systems, in these hydrogels are performed by pulsed field gradient nuclear magnetic resonance. Depending on the mesh size, ξ, and on the polymer volume fraction of the hydrogel after swelling, ϕ, it is possible to tune the relative ATP diffusion coefficient D/D0 in the hydrogels to values between 0.14 and 0.77 compared to the ATP diffusion coefficient D0 in water. The diffusion coefficients of ATP in these hydrogels are compared with predictions of various mathematical expressions developed under different model assumptions. The experimental data are found to be in good agreement with the predictions of a modified obstruction model or the free volume theory in combination with the sieving behavior of the polymer chains. No reasonable agreement was found with the pure hydrodynamic model.

Investigation of copper (Cu2+) adsorption performances and gamma radiation dose effect of polymeric hydrogel

NASA Astrophysics Data System (ADS)

Hassan, Safia; Yasin, Tariq; Imran, Zahid; Batool, Syeda Sitwat

2018-02-01

In present study, series of gamma irradiated poly(acrylic acid)/Penytriethoxytrisilane (PTES) based hydrogels were synthesized. The hydrogels were used for the adsorption of Cu2+ from the aqueous solution. Batch adsorption experiments were performed by varying contact time (0-10 hours), pH value (2-6), hydrogels weight (15-155 mg) and initial Cu2+ concentration (0.003-90 mg/L). The results indicated that lowering the gamma irradiation dose (30-15 kGy) and PTES amount (1.65-0.83 μmol) into hydrogel polymeric networks, improved the initial rate of adsorption and final adsorption capacity of hydrogel for Cu2+. AA40/15 had 143.4mg/g Cu2+ adsorption capacity higher than AA80/30 which is 106.0mg/g. Hydrogels exhibited maximum o adsorption capacity for Cu2+ within a wide pH range. All adsorption data was described by the pseudo—first order and second order kinetic model equations and isotherm data by Langmuir model. FTIR spectra analysis before and after adsorption of Cu2+ on the AA hydrogels gave detail analysis of adsorption mechanism. The behavior of adsorption expressed that the enhanced adsorption capacity was due to the porous structure and e presence of functional groups onto surface of adsorbate. It is expected this polymeric hydrogel has potential to work as alternative biomedical sorbents and environmental use as pH altered.

Modification of vital wheat gluten with phosphoric acid to produce high free-solution capacity

USDA-ARS?s Scientific Manuscript database

Wheat gluten reacts with phosphoric acid to produce natural superabsorbent gels. The gel properties are defined by Fourier Transform Infra-red (FTIR) spectroscopy, 2-dimensional gel electrophoresis (2DE), and uptake of water, salt solutions, and aqueous ethanol. Temperatures above 120'C and dry cond...

Reversible Polymer Hydrogels

DTIC Science & Technology

2008-12-01

glucosamine hydrochloride was dissolved in 100 mL of de- ionized water and placed in an ice bath at >5oC and purged with N2 gas for 20 minutes; 3.25...Temperature sensitive hydrogels based on N-isopropyl acrylamide (NIPA) and acryloyl glucosamine (AG) were synthesized using ammonium persulfate (APS) as...hydrogels by copolymerization of poly (N-isopropylacrylamide) (NIPA), and acryloyl glucosamine (AG) a derivative of chi- tosan, a biopolymer from

Characterization of Particle Translocation through Mucin Hydrogels

PubMed Central

Lieleg, Oliver; Vladescu, Ioana; Ribbeck, Katharina

2010-01-01

Abstract Biological functional entities surround themselves with selective barriers that control the passage of certain classes of macromolecules while rejecting others. A prominent example of such a selective permeability barrier is given by mucus. Mucus is a biopolymer-based hydrogel that lines all wet epithelial surfaces of the human body. It regulates the uptake of nutrients from our gastrointestinal system, adjusts itself with the menstrual cycle to control the passage of sperm, and shields the underlying cells from pathogens such as bacteria and viruses. In the case of drug delivery, the mucus barrier needs to be overcome for successful medical treatment. Despite its importance for both physiology and medical applications, the underlying principles which regulate the permeability of mucus remain enigmatic. Here, we analyze the mobility of microscopic particles in reconstituted mucin hydrogels. We show that electrostatic interactions between diffusing particles and mucin polymers regulate the permeability properties of reconstituted mucin hydrogels. As a consequence, various parameters such as particle surface charge and mucin density, and buffer conditions such as pH and ionic strength, can modulate the microscopic barrier function of the mucin hydrogel. Our findings suggest that the permeability of a biopolymer-based hydrogel such as native mucus can be tuned to a wide range of settings in different compartments of our bodies. PMID:20441741

Stretchable All-Gel-State Fiber-Shaped Supercapacitors Enabled by Macromolecularly Interconnected 3D Graphene/Nanostructured Conductive Polymer Hydrogels.

PubMed

Li, Panpan; Jin, Zhaoyu; Peng, Lele; Zhao, Fei; Xiao, Dan; Jin, Yong; Yu, Guihua

2018-05-01

Nanostructured conductive polymer hydrogels (CPHs) have been extensively applied in energy storage owing to their advantageous features, such as excellent electrochemical activity and relatively high electrical conductivity, yet the fabrication of self-standing and flexible electrode-based CPHs is still hampered by their limited mechanical properties. Herein, macromolecularly interconnected 3D graphene/nanostructured CPH is synthesized via self-assembly of CPHs and graphene oxide macrostructures. The 3D hybrid hydrogel shows uniform interconnectivity and enhanced mechanical properties due to the strong macromolecular interaction between the CPHs and graphene, thus greatly reducing aggregation in the fiber-shaping process. A proof-of-concept all-gel-state fibrous supercapacitor based on the 3D polyaniline/graphene hydrogel is fabricated to demonstrate the outstanding flexibility and mouldability, as well as superior electrochemical properties enabled by this 3D hybrid hydrogel design. The proposed device can achieve a large strain (up to ≈40%), and deliver a remarkable volumetric energy density of 8.80 mWh cm -3 (at power density of 30.77 mW cm -3 ), outperforming many fiber-shaped supercapacitors reported previously. The all-hydrogel design opens up opportunities in the fabrication of next-generation wearable and portable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel vehicle for local protein delivery to the inner ear: injectable and biodegradable thermosensitive hydrogel loaded with PLGA nanoparticles.

PubMed

Dai, Juan; Long, Wei; Liang, Zhongping; Wen, Lu; Yang, Fan; Chen, Gang

2018-01-01

Delivery of biomacromolecular drugs into the inner ear is challenging, mainly because of their inherent instability as well as physiological and anatomical barriers. Therefore, protein-friendly, hydrogel-based delivery systems following local administration are being developed for inner ear therapy. Herein, biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing interferon α-2 b (IFN α-2 b) were loaded in chitosan/glycerophosphate (CS/GP)-based thermosensitive hydrogel for IFN delivery by intratympanic injection. The injectable hydrogel possessed a physiological pH and formed semi-solid gel at 37 °C, with good swelling and deswelling properties. The CS/GP hydrogel could slowly degrade as visualized by scanning electron microscopy (SEM). The presence of NPs in CS/GP gel largely influenced in vitro drug release. In the guinea pig cochlea, a 1.5- to 3-fold increase in the drug exposure time of NPs-CS/GP was found than those of the solution, NPs and IFN-loaded hydrogel. Most importantly, a prolonged residence time was attained without obvious histological changes in the inner ear. This biodegradable, injectable, and thermosensitive NPs-CS/GP system may allow longer delivery of protein drugs to the inner ear, thus may be a potential novel vehicle for inner ear therapy.

Lignin-based hydrogels with "super-swelling" capacities for dye removal.

PubMed

Domínguez-Robles, Juan; Peresin, María Soledad; Tamminen, Tarja; Rodríguez, Alejandro; Larrañeta, Eneko; Jääskeläinen, Anna-Stiina

2018-04-12

Lignin is a complex natural polymer and it is one of the main constituent of the lignocellulosic biomass. Moreover, it is a bio-renewable material and it is available in large amounts as by-product from the forest industry. Lignin-based hydrogels with high swelling capabilities were prepared by crosslinking poly (methyl vinyl ether co-maleic acid) and different technical lignins in ammonium and sodium hydroxide solutions. The produced hydrogels showed a wide range of water absorption capacities varying from 13 to 130 g of water per 1 g of sample. It was observed that the higher the water uptake the poorer mechanical performance, as evaluated in terms of storage and loss modulus (G' and G″, respectively) of the materials. Methylene blue (MB) was used as a model dye to evaluate the adsorption and release capabilities of the lignin hydrogels. Results suggested that these hydrogels showed a high MB removal efficiency, which ranged from 12 to 96%. On the contrary, the percentages of MB released depended on the negative surface charge of the hydrogels, showing values which ranged from 0.06 to 0.35%. Thus, these materials have potential to be used as adsorbents for the removal of organic dyes from waste water. Copyright © 2018 Elsevier B.V. All rights reserved.

Biomimetic hydrogels for biosensor implant biocompatibility: electrochemical characterization using micro-disc electrode arrays (MDEAs).

PubMed

Justin, Gusphyl; Finley, Stephen; Abdur Rahman, Abdur Rub; Guiseppi-Elie, Anthony

2009-02-01

Our interest is in the development of engineered microdevices for continuous remote monitoring of intramuscular lactate, glucose, pH and temperature during post-traumatic hemorrhaging. Two important design considerations in the development of such devices for in vivo diagnostics are discussed; the utility of micro-disc electrode arrays (MDEAs) for electrochemical biosensing and the application of biomimetic, bioactive poly(HEMA)-based hydrogel composites for implant biocompatibility. A poly(HEMA)-based hydrogel membrane containing polyethylene glycol (PEG) was UV cross-linked with tetraethyleneglycol diacrylate following application to MDEAs (50 mum discs) and to 250 mum diameter gold electrodes within 8-well culture ware. Cyclic voltammetry (CV) of the MDEAs revealed a reduction in the apparent diffusion coefficient of ferrocenemonocarboxylic acid (FcCO(2)H), from 6.68 x 10(-5) to 6.74 x 10(-6) cm(2)/s for the uncoated and 6 mum thick hydrogel coated devices, respectively. Single frequency (4 kHz) temporal impedance measurements of the hydrogels in the 8-well culture ware showed a reversible 5% change in the absolute impedance of the hydrogels when exposed to a pH change between 6.1 to 7.2 and a 20% drop between pH 6.1 and 8.8.

Self healing hydrogels composed of amyloid nano fibrils for cell culture and stem cell differentiation.

PubMed

Jacob, Reeba S; Ghosh, Dhiman; Singh, Pradeep K; Basu, Santanu K; Jha, Narendra Nath; Das, Subhadeep; Sukul, Pradip K; Patil, Sachin; Sathaye, Sadhana; Kumar, Ashutosh; Chowdhury, Arindam; Malik, Sudip; Sen, Shamik; Maji, Samir K

2015-06-01

Amyloids are highly ordered protein/peptide aggregates associated with human diseases as well as various native biological functions. Given the diverse range of physiochemical properties of amyloids, we hypothesized that higher order amyloid self-assembly could be used for fabricating novel hydrogels for biomaterial applications. For proof of concept, we designed a series of peptides based on the high aggregation prone C-terminus of Aβ42, which is associated with Alzheimer's disease. These Fmoc protected peptides self assemble to β sheet rich nanofibrils, forming hydrogels that are thermoreversible, non-toxic and thixotropic. Mechanistic studies indicate that while hydrophobic, π-π interactions and hydrogen bonding drive amyloid network formation to form supramolecular gel structure, the exposed hydrophobic surface of amyloid fibrils may render thixotropicity to these gels. We have demonstrated the utility of these hydrogels in supporting cell attachment and spreading across a diverse range of cell types. Finally, by tuning the stiffness of these gels through modulation of peptide concentration and salt concentration these hydrogels could be used as scaffolds that can drive differentiation of mesenchymal stem cells. Taken together, our results indicate that small size, ease of custom synthesis, thixotropic nature makes these amyloid-based hydrogels ideally suited for biomaterial/nanotechnology applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biocompatibility and inflammatory response in vitro and in vivo to gelatin-based biomaterials with tailorable elastic properties.

PubMed

Ullm, Sandra; Krüger, Anne; Tondera, Christoph; Gebauer, Tim P; Neffe, Axel T; Lendlein, Andreas; Jung, Friedrich; Pietzsch, Jens

2014-12-01

Hydrogels prepared from gelatin and lysine diisocyanate ethyl ester provide tailorable elastic properties and degradation behavior. Their interaction with human aortic endothelial cells (HAEC) as well as human macrophages (Mɸ) and granulocytes (Gɸ) were explored. The experiments revealed a good biocompatibility, appropriate cell adhesion, and cell infiltration. Direct contact to hydrogels, but not contact to hydrolytic or enzymatic hydrogel degradation products, resulted in enhanced cyclooxygenase-2 (COX-2) expression in all cell types, indicating a weak inflammatory activation in vitro. Only Mɸ altered their cytokine secretion profile after direct hydrogel contact, indicating a comparably pronounced inflammatory activation. On the other hand, in HAEC the expression of tight junction proteins, as well as cytokine and matrix metalloproteinase secretion were not influenced by the hydrogels, suggesting a maintained endothelial cell function. This was in line with the finding that in HAEC increased thrombomodulin synthesis but no thrombomodulin membrane shedding occurred. First in vivo data obtained after subcutaneous implantation of the materials in immunocompetent mice revealed good integration of implants in the surrounding tissue, no progredient fibrous capsule formation, and no inflammatory tissue reaction in vivo. Overall, the study demonstrates the potential of gelatin-based hydrogels for temporal replacement and functional regeneration of damaged soft tissue. Copyright © 2014 Elsevier Ltd. All rights reserved.

In Situ Gelation-Induced Death of Cancer Cells Based on Proteinosomes.

PubMed

Zhou, Yuting; Song, Jianmin; Wang, Lei; Xue, Xuting; Liu, Xiaoman; Xie, Hui; Huang, Xin

2017-08-14

Hydrogels are an excellent type of material that can be utilized as a platform for cell culture. However, when a bulky hydrogel forms on the inside of cancer cells, the result would be different. In this study, we demonstrate a method for in situ gelation inside cancer cells that can efficiently induce cell death. Glutathione-responsive proteinosomes with good biocompatibility were prepared as carriers for sodium alginate to be endocytosed by cancer cells, where the chelation between sodium alginate and free calcium ions in the culture medium occurs during the diffusion process. The uptake of the hydrogel-loaded proteinosomes into the cancer cells, and then the triggered release of hydrogel with concomitant aggregation, was well-confirmed by monitoring the change of the Young's modulus of the cells based on AFM force measurements. Accordingly, when a large amount of hydrogel formed in cells, the cell viability would be inhibited by ∼90% by MTT assay at a concentration of 5.0 μM of hydrogel-loaded proteinosomes after 48 h incubation, which clearly proves the feasibility of the demonstrated method for killing cancer cells. Although more details regarding the mechanism of cell death should be conducted in the near future, such a demonstrated method of in situ gelation inside cells provides another choice for killing cancer cells.

Chromatographic matrix based on hydrogel-coated reticulated polyurethane foams, prepared by gamma irradiation

NASA Astrophysics Data System (ADS)

Sánchez, Mirna L.; Giménez, Claudia Y.; Delgado, Juan F.; Martínez, Leandro J.; Grasselli, Mariano

2017-12-01

Novel chromatographic materials for protein purification with high adsorption capacity and fouling resistance are highly demanded to improve downstream processes. Here, we describe a novel adsorptive material based on reticulated polyurethane foam (rPUF) coated with a functional hydrogel layer. rPUF provides physical rigidity through its macroscopic structure, whereas the hydrogel layer provides capacity to adsorb proteins by specific interactions. The hydrogel coating process was performed by the dip-coating method, using a polyvinyl alcohol (PVA) solution. The PVA hydrogel was linked to the rPUF material by using a radiation-induced crosslinking process in aqueous ethanol solution. The ethanol in the solvent mixture allowed a balance between PVA swelling and PVA dissolution during the irradiation step. The resulting material showed higher thermal stability than the non-irradiated one. In addition, a simultaneous radiation-induced grafting polymerization (SRIGP) was done by simple addition of glycidyl methacrylate monomer into the irradiation solution. In a further step, sulfonic ligands were included specifically in the hydrogel layer, which contained around 200% of PVA respect to the original rPUF. Materials were characterized by FT-IR, thermogravimetric analysis, SEM microscopy and EDX analysis. The cation-exchange rPUF material was functionally characterized by the Langmuir isotherm and a dynamic adsorption experiment to analyze the chromatographic properties for protein purification processes.

Desmosine-Inspired Cross-Linkers for Hyaluronan Hydrogels

NASA Astrophysics Data System (ADS)

Hagel, Valentin; Mateescu, Markus; Southan, Alexander; Wegner, Seraphine V.; Nuss, Isabell; Haraszti, Tamás; Kleinhans, Claudia; Schuh, Christian; Spatz, Joachim P.; Kluger, Petra J.; Bach, Monika; Tussetschläger, Stefan; Tovar, Günter E. M.; Laschat, Sabine; Boehm, Heike

2013-06-01

We designed bioinspired cross-linkers based on desmosine, the cross-linker in natural elastin, to prepare hydrogels with thiolated hyaluronic acid. These short, rigid cross-linkers are based on pyridinium salts (as in desmosine) and can connect two polymer backbones. Generally, the obtained semi-synthetic hydrogels are form-stable, can withstand repeated stress, have a large linear-elastic range, and show strain stiffening behavior typical for biopolymer networks. In addition, it is possible to introduce a positive charge to the core of the cross-linker without affecting the gelation efficiency, or consequently the network connectivity. However, the mechanical properties strongly depend on the charge of the cross-linker. The properties of the presented hydrogels can thus be tuned in a range important for engineering of soft tissues by controlling the cross-linking density and the charge of the cross-linker.

Gelatin-based hydrogel for vascular endothelial growth factor release in peripheral nerve tissue engineering.

PubMed

Gnavi, S; di Blasio, L; Tonda-Turo, C; Mancardi, A; Primo, L; Ciardelli, G; Gambarotta, G; Geuna, S; Perroteau, I

2017-02-01

Hydrogels are promising materials in regenerative medicine applications, due to their hydrophilicity, biocompatibility and capacity to release drugs and growth factors in a controlled manner. In this study, biocompatible and biodegradable hydrogels based on blends of natural polymers were used in in vitro and ex vivo experiments as a tool for VEGF-controlled release to accelerate the nerve regeneration process. Among different candidates, the angiogenic factor VEGF was selected, since angiogenesis has been long recognized as an important and necessary step during tissue repair. Recent studies have pointed out that VEGF has a beneficial effect on motor neuron survival and Schwann cell vitality and proliferation. Moreover, VEGF administration can sustain and enhance the growth of regenerating peripheral nerve fibres. The hydrogel preparation process was optimized to allow functional incorporation of VEGF, while preventing its degradation and denaturation. VEGF release was quantified through ELISA assay, whereas released VEGF bioactivity was validated in human umbilical vein endothelial cells (HUVECs) and in a Schwann cell line (RT4-D6P2T) by assessing VEGFR-2 and downstream effectors Akt and Erk1/2 phosphorylation. Moreover, dorsal root ganglia explants cultured on VEGF-releasing hydrogels displayed increased neurite outgrowth, providing confirmation that released VEGF maintained its effect, as also confirmed in a tubulogenesis assay. In conclusion, a gelatin-based hydrogel system for bioactive VEGF delivery was developed and characterized for its applicability in neural tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

Thiolated hyaluronan-based hydrogels crosslinked using oxidized glutathione: an injectable matrix designed for ophthalmic applications.

PubMed

Zarembinski, Thomas I; Doty, Nathaniel J; Erickson, Isaac E; Srinivas, Ramya; Wirostko, Barbara M; Tew, William P

2014-01-01

Future ophthalmic therapeutics will require the sustained delivery of bioactive proteins and nucleic acid-based macromolecules and/or provide a suitable microenvironment for the localization and sustenance of reparative progenitor cells after transplantation into or onto the eye. Water-rich hydrogels are ideal vehicles for such cargo, but few have all the qualities desired for novel ophthalmic use, namely in situ gelation speed, cytocompatibility, biocompatibility and capacity to functionalize. We describe here the development of an ophthalmic-compatible crosslinking system using oxidized glutathione (GSSG), a physiologically relevant molecule with a history of safe use in humans. When GSSG is used in conjunction with an existing hyaluronate-based, in situ crosslinkable hydrogel platform, gels form in less than 5 min using the thiol-disulfide exchange reaction. This GSSG hydrogel supports the 3-D culture of adipose-derived stem cells in vitro and shows biocompatibility in preliminary intracutaneous and subconjunctival experiments in vivo. In addition, the thiol-disulfide exchange reaction can also be used in conjunction with other thiol-compatible chemistries to covalently link peptides for more complex formulations. These data suggest that this hydrogel could be well suited for local ocular delivery, focusing initially on front of the eye therapies. Subsequent uses of the hydrogel include delivery of back of the eye treatments and eventually into other soft, hyaluronan-rich tissues such as those from the liver and brain. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Visual and portable strategy for copper(II) detection based on a striplike poly(thymine)-caged and microwell-printed hydrogel.

PubMed

Qing, Zhihe; Mao, Zhengui; Qing, Taiping; He, Xiaoxiao; Zou, Zhen; He, Dinggeng; Shi, Hui; Huang, Jin; Liu, Jianbo; Wang, Kemin

2014-11-18

Due to its importance to develop strategies for copper(II) (Cu(2+)) detection, we here report a visual and portable strategy for Cu(2+) detection based on designing and using a strip-like hydrogel. The hydrogel is functionalized through caging poly(thymine) as probes, which can effectively template the formation of fluorescent copper nanoparticles (CuNPs) in the presence of the reductant (ascorbate) and Cu(2+). On the hydrogel's surface, uniform wells of microliter volume (microwells) are printed for sample-injection. When the injected sample is stained by Cu(2+), fluorescent CuNPs will be in situ templated by poly T in the hydrogel. With ultraviolet (UV) irradiation, the red fluorescence of CuNPs can be observed by naked-eye and recorded by a common camera without complicated instruments. Thus, the strategy integrates sample-injection, reaction and indication with fast signal response, providing an add-and-read manner for visual and portable detection of Cu(2+), as well as a strip-like strategy. Detection ability with a detectable minimum concentration of 20 μM and practically applicable properties have been demonstrated, such as resistance to environmental interference and good constancy, indicating that the strategy holds great potential and significance for popular detection of Cu(2+), especially in remote regions. We believe that the strip-like hydrogel-based methodology is also applicable to other targets by virtue of altering probes.

Structural evolution of photocrosslinked silk fibroin and silk fibroin-based hybrid hydrogels: A small angle and ultra-small angle scattering investigation.

PubMed

Whittaker, Jasmin L; Balu, Rajkamal; Knott, Robert; de Campo, Liliana; Mata, Jitendra P; Rehm, Christine; Hill, Anita J; Dutta, Naba K; Roy Choudhury, Namita

2018-07-15

Regenerated Bombyx mori silk fibroin (RSF) is a widely recognized protein for biomedical applications; however, its hierarchical gel structure is poorly understood. In this paper, the hierarchical structure of photocrosslinked RSF and RSF-based hybrid hydrogel systems: (i) RSF/Rec1-resilin and (ii) RSF/poly(N-vinylcaprolactam (PVCL) is reported for the first time using small-angle scattering (SAS) techniques. The structure of RSF in dilute to concentrated solution to fabricated hydrogels were characterized using small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) techniques. The RSF hydrogel exhibited three distinctive structural characteristics: (i) a Porod region in the length scale of 2 to 3nm due to hydrophobic domains (containing β-sheets) which exhibits sharp interfaces with the amorphous matrix of the hydrogel and the solvent, (ii) a Guinier region in the length scale of 4 to 20nm due to hydrophilic domains (containing turns and random coil), and (iii) a Porod-like region in the length scale of few micrometers due to water pores/channels exhibiting fractal-like characteristics. Addition of Rec1-resilin or PVCL to RSF and subsequent crosslinking systematically increased the nanoscale size of hydrophobic and hydrophilic domains, whereas decreased the homogeneity of pore size distribution in the microscale. The presented results have implications on the fundamental understanding of the structure-property relationship of RSF-based hydrogels. Copyright © 2018. Published by Elsevier B.V.

A novel pH-responsive hydrogel-based on calcium alginate engineered by the previous formation of polyelectrolyte complexes (PECs) intended to vaginal administration.

PubMed

Ferreira, Natália Noronha; Perez, Taciane Alvarenga; Pedreiro, Liliane Neves; Prezotti, Fabíola Garavello; Boni, Fernanda Isadora; Cardoso, Valéria Maria de Oliveira; Venâncio, Tiago; Gremião, Maria Palmira Daflon

2017-10-01

This work aimed to develop a calcium alginate hydrogel as a pH responsive delivery system for polymyxin B (PMX) sustained-release through the vaginal route. Two samples of sodium alginate from different suppliers were characterized. The molecular weight and M/G ratio determined were, approximately, 107 KDa and 1.93 for alginate_S and 32 KDa and 1.36 for alginate_V. Polymer rheological investigations were further performed through the preparation of hydrogels. Alginate_V was selected for subsequent incorporation of PMX due to the acquisition of pseudoplastic viscous system able to acquiring a differential structure in simulated vaginal microenvironment (pH 4.5). The PMX-loaded hydrogel (hydrogel_PMX) was engineered based on polyelectrolyte complexes (PECs) formation between alginate and PMX followed by crosslinking with calcium chloride. This system exhibited a morphology with variable pore sizes, ranging from 100 to 200 μm and adequate syringeability. The hydrogel liquid uptake ability in an acid environment was minimized by the previous PECs formation. In vitro tests evidenced the hydrogels mucoadhesiveness. PMX release was pH-dependent and the system was able to sustain the release up to 6 days. A burst release was observed at pH 7.4 and drug release was driven by an anomalous transport, as determined by the Korsmeyer-Peppas model. At pH 4.5, drug release correlated with Weibull model and drug transport was driven by Fickian diffusion. The calcium alginate hydrogels engineered by the previous formation of PECs showed to be a promising platform for sustained release of cationic drugs through vaginal administration.

Hydrogel-coated microfluidic channels for cardiomyocyte culture

PubMed Central

Annabi, Nasim; Selimović, Šeila; Cox, Juan Pablo Acevedo; Ribas, João; Bakooshli, Mohsen Afshar; Heintze, Déborah; Weiss, Anthony S.; Cropek, Donald; Khademhosseini, Ali

2013-01-01

The research areas of tissue engineering and drug development have displayed increased interest in organ-on-a-chip studies, in which physiologically or pathologically relevant tissues can be engineered to test pharmaceutical candidates. Microfluidic technologies enable the control of the cellular microenvironment for these applications through the topography, size, and elastic properties of the microscale cell culture environment, while delivering nutrients and chemical cues to the cells through continuous media perfusion. Traditional materials used in the fabrication of microfluidic devices, such as poly(dimethylsiloxane) (PDMS), offer high fidelity and high feature resolution, but do not facilitate cell attachment. To overcome this challenge, we have developed a method for coating microfluidic channels inside a closed PDMS device with a cell-compatible hydrogel layer. We have synthesized photocrosslinkable gelatin and tropoelastin-based hydrogel solutions that were used to coat the surfaces under continuous flow inside 50 μm wide, straight microfluidic channels to generate a hydrogel layer on the channel walls. Our observation of primary cardiomyocytes seeded on these hydrogel layers showed preferred attachment as well as higher spontaneous beating rates on tropoelastin coatings compared to gelatin. In addition, cellular attachment, alignment and beating were stronger on 5 % (w/v) hydrogel-coated devices than on 10 % (w/v) gel-coated channels. Our results demonstrate that cardiomyocytes respond favorably to the elastic, soft tropoelastin culture substrates, indicating that tropoelastin-based hydrogels may be a suitable coating choice for some organ-on-a-chip applications. We anticipate that the proposed hydrogel coating method and tropoelastin as a cell culture substrate may be useful for the generation of elastic tissues, e.g. blood vessels, using microfluidic approaches. PMID:23728018

Evaluation of Gentamicin and Lidocaine Release Profile from Gum Acacia-crosslinked-poly(2-hydroxyethylmethacrylate)-carbopol Based Hydrogels.

PubMed

Singh, Baljit; Dhiman, Abhishek

2017-01-01

No doubt, the prevention of infection is an indispensable aspect of the wound management, but, simultaneous wound pain relief is also required. Therefore, herein this article, incorporation of antibiotic agent 'gentamicin' and pain relieving agent 'lidocaine' into hydrogel wound dressings, prepared by using acacia gum, carbopol and poly(2-hydroxyethylmethacrylate) polymers, has been carried out. The hydrogels were evaluated as a drug carrier for model drugs gentamicin and lidocaine. Synthesis of hydrogel wound dressing was carried out by free radical polymerization technique. The drug loading was carried out by swelling equilibrium method and gel strength of hydrogels was measured by a texture analyzer. Porous microstructure of the hydrogel was observed in cryo-SEM images. The hydrogel showed mesh size 37.29 nm, cross-link density 2.19× 10-5 mol/cm3, molecular weight between two cross-links 60.25× 10-3 g/mol and gel strength 0.625±0.112 N in simulated wound fluid. It is concluded that the pH of swelling medium has influenced the network structure of hydrogel i.e., molecular weight of the polymer chain between two neighboring cross links, crosslink density and the corresponding mesh size. A good correlation was established between gel strength and network parameters. Cryo-SEM images showed porous morphology of hydrogels. These hydrogels were found to be biodegradable and antimicrobial in nature. Drug release occurred through Fickian diffusion mechanism and release profile was best fitted in first order model. Overall it is concluded that modification in GA has led to formation of a porous hydrogels for wound dressing applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Synthesis of stiffness-tunable and cell-responsive Gelatin-poly(ethylene glycol) hydrogel for three-dimensional cell encapsulation.

PubMed

Cao, Ye; Lee, Bae Hoon; Peled, Havazelet Bianco; Venkatraman, Subbu S

2016-10-01

Biosynthetic poly(ethylene glycol) (PEG)-based hydrogels have been extensively investigated as extracellular matrix (ECM) mimicking gels as they retain the benefits of both ECM (biological cues) and synthetic hydrogels (tunable mechanical properties). In this article, we developed and characterized a new gelatin-PEG (GP) hydrogel that retains the benefits of gelatin and synthetic hydrogels. In this strategy, the thiolation of gelatin was accomplished by reacting with Traut's reagent; the thiolated gelatin was then conjugated to one end of PEG diacrylate (PEGDA) by Michael-type addition reaction. Two kinds of GP precursors, GP30 and GP60, were synthesized by changing the amount of Traut's reagent, while the weight ratio between thiolated-gelatin and PEGDA of GP30 and GP60 was 1.451:1 and 0.785:1, respectively. Finally, neonatal human dermal fibroblasts were encapsulated into the hydrogel by cross-linking the remaining double bonds of precursor under ultraviolet light. These GP hydrogels can encapsulate the fibroblasts in situ with high cell viability. Moreover, the behaviors of cells within the GP hydrogels can be modulated by varying the cross-linking density of GP hydrogel (storage modulus from 40 to 2000 Pa). In particular, this article showed that a minimum amount of cell-binding motifs (gelatin >2.30 wt/vol % and 44.0% dry weight percentage) are required for attachment; and appropriate initial rheological and structural properties (storage modulus <∼100 Pa and mesh size >∼150 nm) can accelerate the attachment of cells and improve cell viability. Hence, this mixed-hydrogel platform allows an easily control hydrogel structure and modulates cell behavior to reconstruct new tissue in the three-dimensional microenvironments. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2401-2411, 2016. © 2016 Wiley Periodicals, Inc.

A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers

PubMed Central

Raza, Faisal; Zafar, Hajra; Zhu, Ying; Ren, Yuan; -Ullah, Aftab; Khan, Asif Ullah; He, Xinyi; Han, Han; Aquib, Md; Boakye-Yiadom, Kofi Oti; Ge, Liang

2018-01-01

Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS) and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All these dynamic properties of hydrogels have increased the interest in their use as a carrier for peptides and proteins to be released slowly in a sustained manner. Peptide and proteins are remarkable therapeutic agents in today’s world that allow the treatment of severe, chronic and life-threatening diseases, such as diabetes, rheumatoid arthritis, hepatitis. Despite few limitations, hydrogels provide fine tuning of proteins and peptides delivery with enormous impact in clinical medicine. Novels drug delivery systems composed of smart peptides and molecules have the ability to drive self-assembly and form hydrogels at physiological pH. These hydrogels are significantly important for biological and medical fields. The primary objective of this article is to review current issues concerned with the therapeutic peptides and proteins and impact of remarkable properties of hydrogels on these therapeutic agents. Different routes for pharmaceutical peptides and proteins and superiority over other drugs candidates are presented. Recent advances based on various approaches like self-assembly of peptides and small molecules to form novel hydrogels are also discussed. The article will also review the literature concerning the classification of hydrogels on a different basis, polymers used, “release mechanisms” their physical and chemical characteristics and diverse applications. PMID:29346275

Synthesis and characterization of cloisite-30B clay dispersed poly (acryl amide/sodium alginate)/AgNp hydrogel composites for the study of BSA protein drug delivery and antibacterial activity

NASA Astrophysics Data System (ADS)

Nanjunda Reddy, B. H.; Ranjan Rauta, Pradipta; Venkatalakshimi, V.; Sreenivasa, Swamy

2018-02-01

The aim of this research is to inspect the effect of Cloisite-30B (C30B) modified clay dispersed poly (acrylamide-co-Sodiumalginate)/AgNp hydrogel nanocomposites (PASA/C30B/Ag) for drug delivery and antibacterial activity. A novel hydrogel composite based sodium alginate (SA) and the inorganic modified clay with silver nano particle (C30B/AgNps)polymer hydrogel composites are synthesized via the graft copolymerization of acrylamide (AAm) in an aqueous medium with methylene bisacrylamide (MBA) as a crosslinking agent and ammonium per sulfate(APS) as an initiator. The UV/Visible spectroscopy of obtained composites is successfully studied, which confirms the occurrence of AgNps in the hydrogel composites. And the swelling capacity and bovine serum albumin (BSA) protein as model drug delivery study for these hydrogel nanocomposites have been carried out. The C30B/Ag filled hydrogel composites exhibit superior water absorbency or swelling capacity compared to pure samples and it is establish that the formulations with clay (C30B) dispersed silver nanocomposite hydrogels show improved and somewhat faster rate of drug delivery than other formulations(pure systems) and SEM and TEM reports suggests that the size of AgNps in the composite hydrogels is in the range of 5-10 nm with shrunken surface and the antibacterial characterizations for gram positive and gram negative bacteria are carried out by using Streptococcus faecalis (S. Faecalis) and Escherichia coli (E.coli) as model bacteria and the hydrogel composites of PASA/C30B/Ag shows exceptional antibacterial activity against both the bacteria as compared to pure hydrogel composites samples.

Visual in vivo degradation of injectable hydrogel by real-time and non-invasive tracking using carbon nanodots as fluorescent indicator.

PubMed

Wang, Lei; Li, Baoqiang; Xu, Feng; Li, Ying; Xu, Zheheng; Wei, Daqing; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu

2017-11-01

Visual in vivo degradation of hydrogel by fluorescence-related tracking and monitoring is crucial for quantitatively depicting the degradation profile of hydrogel in a real-time and non-invasive manner. However, the commonly used fluorescent imaging usually encounters limitations, such as intrinsic photobleaching of organic fluorophores and uncertain perturbation of degradation induced by the change in molecular structure of hydrogel. To address these problems, we employed photoluminescent carbon nanodots (CNDs) with low photobleaching, red emission and good biocompatibility as fluorescent indicator for real-time and non-invasive visual in vitro/in vivo degradation of injectable hydrogels that are mixed with CNDs. The in vitro/in vivo toxicity results suggested that CNDs were nontoxic. The embedded CNDs in hydrogels did not diffuse outside in the absence of hydrogel degradation. We had acquired similar degradation kinetics (PBS-Enzyme) between gravimetric and visual determination, and established mathematical equation to quantitatively depict in vitro degradation profile of hydrogels for the predication of in vivo hydrogel degradation. Based on the in vitro data, we developed a visual platform that could quantitatively depict in vivo degradation behavior of new injectable biomaterials by real-time and non-invasive fluorescence tracking. This fluorescence-related visual imaging methodology could be applied to subcutaneous degradation of injectable hydrogel with down to 7 mm depth in small animal trials so far. This fluorescence-related visual imaging methodology holds great potentials for rational design and convenient in vivo screening of biocompatible and biodegradable injectable hydrogels in tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning.

PubMed

Sivakumaran, Daryl; Bakaic, Emilia; Campbell, Scott B; Xu, Fei; Mueller, Eva; Hoare, Todd

2018-04-16

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by the lack of biologically-relevant degradation observed for most smart materials. This is particularly true for temperature-responsive hydrogels, which are almost uniformly based on polymers that are functionally non-degradable (e.g., poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)). As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, a method is required to render the hydrogels (if not fully degradable) at least capable of renal clearance following the required lifetime of the material. To that end, this protocol describes the preparation of hydrolytically-degradable hydrazone-crosslinked hydrogels on multiple length scales based on the reaction between hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit. Specifically, methods to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) are described. In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can be degraded over time to re-form the oligomeric precursor polymers and enable clearance. As such, we anticipate these methods (which may be generically applied to any synthetic water-soluble polymer, not just smart materials) will enable easier translation of synthetic smart materials to clinical applications.

Nanoclay cross-linked semi-IPN silk sericin/poly(NIPAm/LMSH) nanocomposite hydrogel: An outstanding antibacterial wound dressing.

PubMed

Yang, Chaochao; Xue, Rui; Zhang, Qingsong; Yang, Shulin; Liu, Pengfei; Chen, Li; Wang, Ke; Zhang, Xiaoyong; Wei, Yen

2017-12-01

High antibacterial and skin-like hydrogels have always been the perfect wound dressing for human to protect wound from infection. Here, based on silk sericin, we design a series of nanoclay lithium magnesium silicate hydrate (LMSH) cross-linked semi-IPN sericin/poly(NIPAm/LMSH) (HSP) nanocomposite hydrogels and demonstrate advantages in serving as antibacterial wound dressing in comparison with gauze. Firstly, the effect of mass ratios of sericin/(sericin+NIPAm) upon pore structure, feasibility of mechanics and gas permeability of HSP nanocomposite hydrogels were evaluated. Then, the relationship between nanocomposite hydrogel and histological/antimicrobial properties was systematically analyzed. It was found that, the introduction of sericin increased internal pore size, leading to obvious transition from honeycomb to layered structure. Furthermore, as mass ratio of sericin/(sericin+NIPAm) is 20%, the wound healing area treated with nanocomposite hydrogels at 6th day reached up to 83%, 3 times of gauze, and almost recovered at 13th day. Especially, antibacterial mechanism can be thought to be the results that the macromolecular sericin embedded in the nanocomposite hydrogel adsorbed bacteria by charge interaction and micromolecular sericin dissociating out from nanocomposite hydrogels can be adsorbed onto bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of poly(ethylene glycol) hydrogels with different network structures for the application of enzyme immobilization.

PubMed

Choi, Dongkil; Lee, Woojin; Park, Jinwon; Koh, Wongun

2008-01-01

In this study, poly(ethylene glycol) (PEG)-based hydrogels having different network structures were synthesized by UV-initiated photopolymerization and used for the enzyme immobilization. PEGs with different molecular weight were acrylated by derivatizing both ends with acryloyl chloride and photopolymerization of PEG-diacrylate (PEG-DA) yielded crosslinked hydrogel network within 5 seconds. Attachment of acrylate groups and gelation were confirmed by ATR/FT-IR and FT-Raman spectroscopy. Network structures of hydrogels could be easily controlled by changing the molecular weight (MW) of PEG-DA and characterized by calculating molecular weight between crosslinks and mesh size from the swelling measurement. Synthesis of hydrogels with higher MW of PEG produced less crosslinked hydrogels having higher water content, larger value of Mc and mesh size, which resulted in enhanced mass transfer but loss of mechanical properties. For the enzyme immobilization, glucose oxidase (GOX) was immobilized inside PEG hydrogels by means of physical entrapment and covalent immobilization. Encapsulated GOX were covalently bound to PEG backbone using acryloyl-PEG-N-hydroxysuccinimide and maintained their activity over a week period without leakage. Kinetic study indicated that immobilized enzyme inside hydrogel prepared from higher MW of PEG possessed lower apparent Km (Michaelis-Menten constant) and higher activity.

Silk-ionomer and silk-tropoelastin hydrogels as charged three-dimensional culture platforms for the regulation of hMSC response.

PubMed

Calabrese, Rossella; Raia, Nicole; Huang, Wenwen; Ghezzi, Chiara E; Simon, Marc; Staii, Cristian; Weiss, Anthony S; Kaplan, David L

2017-09-01

The response of human bone marrow-derived mesenchymal stem cells (hMSCs) encapsulated in three-dimensional (3D) charged protein hydrogels was studied. Combining silk fibroin (S) with recombinant human tropoelastin (E) or silk ionomers (I) provided protein composite alloys with tunable physicochemical and biological features for regulating the bioactivity of encapsulated hMSCs. The effects of the biomaterial charges on hMSC viability, proliferation and chondrogenic or osteogenic differentiation were assessed. The silk-tropoelastin or silk-ionomers hydrogels supported hMSC viability, proliferation and differentiation. Gene expression of markers for chondrogenesis and osteogenesis, as well as biochemical and histological analysis, showed that hydrogels with different S/E and S/I ratios had different effects on cell fate. The negatively charged hydrogels upregulated hMSC chondrogenesis or osteogenesis, with or without specific differentiation media, and hydrogels with higher tropoelastin content inhibited the differentiation potential even in the presence of the differentiation media. The results provide insight on charge-tunable features of protein-based biomaterials to control hMSC differentiation in 3D hydrogels, as well as providing a new set of hydrogels for the compatible encapsulation and utility for cell functions. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Design and evaluation of novel fast forming pilocarpine-loaded ocular hydrogels for sustained pharmacological response

PubMed Central

Anumolu, SivaNaga S.; Singh, Yashveer; Gao, Dayuan; Stein, Stanley; Sinko, Patrick J.

2009-01-01

Fast forming hydrogels prepared by crosslinking a poly(ethylene glycol) (PEG)-based copolymer containing multiple thiol (SH) groups were evaluated for the controlled ocular delivery of pilocarpine and subsequent pupillary constriction. Physical properties of the hydrogels were characterized using UV-Vis spectrophotometry, transmission electron microscopy (TEM), rheometry, and swelling kinetics. Pilocarpine loading efficiency and release properties were measured in simulated tear fluid. The hydrogel formulations exhibited high drug loading efficiency (~74%). Pilocarpine release was found to be biphasic with release half times of ~2 and 94 h, respectively, and 85–100% of the drug was released over 8-days. Pilocarpine-loaded (2% w/v) hydrogels were evaluated in a rabbit model and compared to a similar dose of drug in aqueous solution. The hydrogels were retained in the eye for the entire period of the study with no observed irritation. Pilocarpine-loaded hydrogels sustained pupillary constriction for 24 h after administration as compared to 3 h for the solution, an 8-fold increase in duration of action. A strong correlation between pilocarpine release and pupillary response was observed. In conclusion, the current studies demonstrate that in situ forming PEG hydrogels possess the viscoelastic, retention, and sustained delivery properties required for an efficient ocular drug delivery system. PMID:19341773

Smart nanocomposite hydrogels based on azo crosslinked graphene oxide for oral colon-specific drug delivery

NASA Astrophysics Data System (ADS)

Hou, Lin; Shi, Yuyang; Jiang, Guixiang; Liu, Wei; Han, Huili; Feng, Qianhua; Ren, Junxiao; Yuan, Yujie; Wang, Yongchao; Shi, Jinjin; Zhang, Zhenzhong

2016-08-01

A safe and efficient nanocomposite hydrogel for colon cancer drug delivery was synthesized using pH-sensitive and biocompatible graphene oxide (GO) containing azoaromatic crosslinks as well as poly (vinyl alcohol) (PVA) (GO-N=N-GO/PVA composite hydrogels). Curcumin (CUR), an anti-cancer drug, was encapsulated successfully into the hydrogel through a freezing and thawing process. Fourier transform infrared spectroscopy, scanning electron microscopy and Raman spectroscopy were performed to confirm the formation and morphological properties of the nanocomposite hydrogel. The hydrogels exhibited good swelling properties in a pH-sensitive manner. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely into the physiological environment of the stomach and small intestine. In vivo imaging analysis, pharmacokinetics and a distribution of the gastrointestinal tract experiment were systematically studied and evaluated as colon-specific drug delivery systems. All the results demonstrated that GO-N=N-GO/PVA composite hydrogels could protect CUR well while passing through the stomach and small intestine to the proximal colon, and enhance the colon-targeting ability and residence time in the colon site. Therefore, CUR loaded GO-N=N-GO/PVA composite hydrogels might potentially provide a theoretical basis for the treatment of colon cancer with high efficiency and low toxicity.

Laponite crosslinked starch/polyvinyl alcohol hydrogels by freezing/thawing process and studying their cadmium ion absorption.

PubMed

Yu, Chen; Tang, Xiaozhi; Liu, Shaowei; Yang, Yuling; Shen, Xinchun; Gao, Chengcheng

2018-05-22

In this study, Laponite RD (LRD) cross-linked hydrogels consisting of starch, polyvinyl alcohol (PVA) were prepared by freezing/thawing process and the influence of LRD content on structure and properties of hydrogels was investigated. FTIR showed a new structure of hydrogen bonding might result from cross-linking reactions between LRD and polymers. X-ray diffraction (XRD) analysis showed that high degree of exfoliation of LRD clay layers had occurred during the preparation of hydrogels. The synergistic effect of physical cross-linking by freeze/thaw cycles and by LRD led to more porous, uniform and stable network, which was shown in SEM images. The melting temperature decreased and thermal stability got improved with the increase of LRD content. Reswelling ratios of hydrogels had the highest value when LRD content was 10%. Additionally, cadmium ion absorption capacity of the hydrogel was studied and the results showed that increasing the concentration of LRD increased absorption ratio and amount of Cd 2+ ion in the solution. In a word, LRD could be used as a physical crosslinker and reinforced agent for starch-PVA based hydrogels and the formed hydrogels could be used as novel type and high capacity absorbent materials in heavy metal removing processes. Copyright © 2018. Published by Elsevier B.V.

3D cell entrapment in crosslinked thiolated gelatin-poly(ethylene glycol) diacrylate hydrogels

PubMed Central

Fu, Yao; Xu, Kedi; Zheng, Xiaoxiang; Giacomin, A. Jeffrey; Mix, Adam W.; Kao, Weiyuan John

2012-01-01

The combined use of natural ECM components and synthetic materials offers an attractive alternative to fabricate hydrogel-based tissue engineering scaffolds to study cell-matrix interactions in three-dimensions (3D). A facile method was developed to modify gelatin with cysteine via a bifunctional PEG linker, thus introducing free thiol groups to gelatin chains. A covalently crosslinked gelatin hydrogel was fabricated using thiolated gelatin and poly(ethylene glycol) diacrylate (PEGdA) via thiol-ene reaction. Unmodified gelatin was physically incorporated in a PEGdA-only matrix for comparison. We sought to understand the effect of crosslinking modality on hydrogel physicochemical properties and the impact on 3D cell entrapment. Compared to physically incorporated gelatin hydrogels, covalently crosslinked gelatin hydrogels displayed higher maximum weight swelling ratio (Qmax), higher water content, significantly lower cumulative gelatin dissolution up to 7 days, and lower gel stiffness. Furthermore, fibroblasts encapsulated within covalently crosslinked gelatin hydrogels showed extensive cytoplasmic spreading and the formation of cellular networks over 28 days. In contrast, fibroblasts encapsulated in the physically incorporated gelatin hydrogels remained spheroidal. Hence, crosslinking ECM protein with synthetic matrix creates a stable scaffold with tunable mechanical properties and with long-term cell anchorage points, thus supporting cell attachment and growth in the 3D environment. PMID:21955690

Effect of Tendon Stem Cells in Chitosan/β-Glycerophosphate/Collagen Hydrogel on Achilles Tendon Healing in a Rat Model.

PubMed

Yang, Zhijin; Cao, Honghui; Gao, Shang; Yang, Mingyu; Lyu, Jingtong; Tang, Kanglai

2017-09-27

BACKGROUND The aim of this study was to determine whether the local application of tendon stem cells (TSCs) with chitosan/β-glycerophosphate/collagen(C/GP/Co) hydrogel promotes healing after an acute Achilles tendon injury in a rat model. MATERIAL AND METHODS Ninety-six Sprague-Dawley (SD) rats were used to make an Achilles tendon defect model, then the animals were randomly divided into 4 groups consisting of 8 rats each: control group, hydrogel group, TSCs group, and TSCs with hydrogel group. At 2, 4, and 6 weeks after treatment, tendon samples were harvested, and the quality of tendon repair was evaluated based on histology, immunohistochemistry, and biomechanical properties. RESULTS Combining TSCs with C/GP/Co hydrogel significantly enhances tendon healing compared with the control, hydrogel, and TSCs groups. The improved healing was indicated by the improvement in histological and immunohistochemistry outcomes and the increase in the biomechanical properties of the regenerated tissue at both 4 and 6 weeks post-injury. CONCLUSIONS This study demonstrates that the transplantation of TSCs combined with C/GP/Co hydrogel significantly improved the histological, immunohistochemistry, and biomechanical outcomes of the regenerated tissue at 4 and 6 weeks after implantation. TSCs with C/GP/Co hydrogel is a potentially effective treatment for tendon injury.

Rapid enrichment of rare-earth metals by carboxymethyl cellulose-based open-cellular hydrogel adsorbent from HIPEs template.

PubMed

Zhu, Yongfeng; Wang, Wenbo; Zheng, Yian; Wang, Feng; Wang, Aiqin

2016-04-20

A series of monolithic open-cellular hydrogel adsorbents based on carboxymethylcellulose (CMC) were prepared through high internal phase emulsions (HIPEs) and used to enrich the rare-earth metals La(3+) and Ce(3+). The changes of pore structure, and the effects of pH, contact time, initial concentration on the adsorption performance were systematically studied. The results show that the as-prepared monolithic hydrogel adsorbents possess good open-cellular framework structure and have fast adsorption kinetics and high adsorption capacity for La(3+) and Ce(3+). The involved adsorption system can reach equilibrium within 30min and the maximal adsorption capacity is determined to be 384.62mg/g for La(3+) and 333.33mg/g for Ce(3+). Moreover, these porous hydrogel adsorbents show an excellent adsorptive reusability for La(3+) and Ce(3+) through five adsorption-desorption cycles. Such a pore hierarchy structure makes this monolithic open-cellular hydrogel adsorbent be an effective adsorbent for effective enrichment of La(3+) and Ce(3+) from aqueous solution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis and characterization of a biocompatible chitosan-based hydrogel cross-linked via 'click' chemistry for controlled drug release.

PubMed

Guaresti, O; García-Astrain, C; Palomares, T; Alonso-Varona, A; Eceiza, A; Gabilondo, N

2017-09-01

A chemically cross-linked chitosan-based hydrogel was successfully synthesized through Diels-Alder (DA) reaction and characterized. The final product was obtained after different steps; on the one hand, furan-modified chitosan (Cs-Fu) was synthesized by the reaction of furfural with the free amino groups of chitosan. On the other hand, highlighting the novelty of the present research, maleimide-functionalized chitosan (Cs-AMI) was prepared by the reaction of a maleimide-modified aminoacid with the amino groups of chitosan through amide coupling. The two complementary chitosan derivatives were cross-linked to the final hydrogel network. Both modification reactions were confirmed by FTIR and 1 H NMR, obtaining a degree of substitution (DS) of 31% and 26% for Cs-Fu and Cs-AMI, respectively. The as-designed hydrogel was analyzed in terms of microstructure, swelling capacity and rheological behaviour. The hydrogel showed pH-sensitivity, biocompatibility and inhibitory bacterial activity, promising features for biomedical applications, particularly for targeted-drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of polymer network parameters of tragacanth gum-based pH responsive hydrogels on drug delivery.

PubMed

Singh, Baljit; Sharma, Vikrant

2014-01-30

The present article deals with design of tragacanth gum-based pH responsive hydrogel drug delivery systems. The characterization of hydrogels has been carried out by SEMs, EDAX, FTIR, (13)C NMR, XRD, TGA/DTA/DTG and swelling studies. The correlation between reaction conditions and structural parameters of polymer networks such as polymer volume fraction in the swollen state (ϕ), Flory-Huggins interaction parameter (χ), molecular weight of the polymer chain between two neighboring cross links (M¯c), crosslink density (ρ) and mesh size (ξ) has been determined. The different kinetic models such as zero order, first order, Higuchi square root law, Korsmeyer-Peppas model and Hixson-Crowell cube root model were applied and it has been observed that release profile of amoxicillin best followed the first order model for the release of drug from the polymer matrix. The swelling of the hydrogels and release of drug from the drug loaded hydrogels occurred through non-Fickian diffusion mechanism in pH 7.4 solution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Triboelectric-Nanogenerator-Based Soft Energy-Harvesting Skin Enabled by Toughly Bonded Elastomer/Hydrogel Hybrids.

PubMed

Liu, Ting; Liu, Mengmeng; Dou, Su; Sun, Jiangman; Cong, Zifeng; Jiang, Chunyan; Du, Chunhua; Pu, Xiong; Hu, Weiguo; Wang, Zhong Lin

2018-03-27

A major challenge accompanying the booming next-generation soft electronics is providing correspondingly soft and sustainable power sources for driving such devices. Here, we report stretchable triboelectric nanogenerators (TENG) with dual working modes based on the soft hydrogel-elastomer hybrid as energy skins for harvesting biomechanical energies. The tough interfacial bonding between the hydrophilic hydrogel and hydrophobic elastomer, achieved by the interface modification, ensures the stable mechanical and electrical performances of the TENGs. Furthermore, the dehydration of this toughly bonded hydrogel-elastomer hybrid is significantly inhibited (the average dehydration decreases by over 73%). With PDMS as the electrification layer and hydrogel as the electrode, a stretchable, transparent (90% transmittance), and ultrathin (380 μm) single-electrode TENG was fabricated to conformally attach on human skin and deform as the body moves. The two-electrode mode TENG is capable of harvesting energy from arbitrary human motions (press, stretch, bend, and twist) to drive the self-powered electronics. This work provides a feasible technology to design soft power sources, which could potentially solve the energy issues of soft electronics.

Fabrication of robust hydrogel coatings on polydimethylsiloxane substrates using micropillar anchor structures with chemical surface modification.

PubMed

Zhang, Hongbin; Bian, Chao; Jackson, John K; Khademolhosseini, Farzad; Burt, Helen M; Chiao, Mu

2014-06-25

A durable hydrophilic and protein-resistant surface of polydimethylsiloxane (PDMS) based devices is desirable in many biomedical applications such as implantable and microfluidic devices. This paper describes a stable antifouling hydrogel coating on PDMS surfaces. The coating method combines chemical modification and surface microstructure fabrication of PDMS substrates. Three-(trimethoxysilyl)propyl methacrylates containing C═C groups were used to modify PDMS surfaces with micropillar array structures fabricated by a replica molding method. The micropillar structures increase the surface area of PDMS surfaces, which facilitates secure bonding with a hydrogel coating compared to flat PMDS surfaces. The adhesion properties of the hydrogel coating on PDMS substrates were characterized using bending, stretching and water immersion tests. Long-term hydrophilic stability (maintaining a contact angle of 55° for a month) and a low protein adsorption property (35 ng/cm(2) of adsorbed BSA-FITC) of the hydrogel coated PDMS were demonstrated. This coating method is suitable for PDMS modification with most crosslinkable polymers containing C═C groups, which can be useful for improving the anti-biofouling performance of PDMS-based biomedical microdevices.