Science.gov

Sample records for alginate scaffold including

  1. Hepatocyte behavior within three-dimensional porous alginate scaffolds.

    PubMed

    Glicklis, R; Shapiro, L; Agbaria, R; Merchuk, J C; Cohen, S

    2000-02-01

    A potential approach to facilitate the performance of implanted hepatocytes is to enable their aggregation and re-expression of their differentiated function prior to implantation. Here we examined the behavior of freshly isolated rat adult hepatocytes seeded within a novel three-dimensional (3-D) scaffold based on alginate. The attractive features of this scaffold include a highly porous structure (sponge-like) with interconnecting pores, and pore sizes with diameters of 100-150 microm. Due to their hydrophilic nature, seeding hepatocytes onto the alginate sponges was efficient. DNA measurements showed that the total cell number within the sponges did not change over 2 weeks, indicating that hepatocytes do not proliferate under these culture conditions. Nearly all seeded cells maintained viability, according to the MTT assay. Within 24 h post-seeding, small clusters of viable cells, were seen scattered within the sponge. More than 90% of the seeded cells participated in the aggregation; the high efficiency is attributed to the non-adherent nature of alginate. The spheroids had smooth boundaries and by day 4 in culture reached an average diameter of 100 microm, which is at the same magnitude of the sponge pore size. The cells appeared to synthesize fibronectin which was deposited on the spheroids. No laminin or collagen type IV were detected in the deposit. The 3-D arrangement of hepatocytes within the alginate sponges promoted their functional expression; within a week the cells secreted the maximal albumin secretion rate of 60 microg albumin/10(6) cells/day. Urea secretion rate did not depend on cell aggregation and was similar to that obtained when hepatocytes were cultured on collagen type I coated dishes (100 microg/10(6) cells/day). Our studies show that alginate sponges can provide a conducive environment to facilitate the performance of cultured hepatocytes by enhancing their aggregation.

  2. PCL/alginate composite scaffolds for hard tissue engineering: fabrication, characterization, and cellular activities.

    PubMed

    Kim, Yong Bok; Kim, Geun Hyung

    2015-02-01

    Alginates have been used widely in biomedical applications because of good biocompatibility, low cost, and rapid gelation in the presence of calcium ions. However, poor mechanical properties and fabrication-ability for three-dimensional shapes have been obstacles in hard-tissue engineering applications. To overcome these shortcomings of alginates, we suggest a new composite system, consisting of a synthetic polymer, poly(ε-caprolactone), and various weight fractions (10-40 wt %) of alginate. The fabricated composite scaffolds displayed a multilayered 3D structure, consisting of microsized composite struts, and they provided a 100% offset for each layer. To show the feasibility of the scaffold for hard tissue regeneration, the composite scaffolds fabricated were assessed not only for physical properties, including surface roughness, tensile strength, and water absorption and wetting, but also in vitro osteoblastic cellular responses (cell-seeding efficiency, cell viability, fluorescence analyses, alkaline phosphatase (ALP) activity, and mineralization) by culturing with preosteoblasts (MC3T3-E1). Due to the alginate components in the composites, the scaffolds showed significantly enhanced wetting behavior, water-absorption (∼12-fold), and meaningful biological activities (∼2.1-fold for cell-seeding efficiency, ∼2.5-fold for cell-viability at 7 days, ∼3.4-fold for calcium deposition), compared with a pure PCL scaffold.

  3. In vitro evaluation of alginate/halloysite nanotube composite scaffolds for tissue engineering.

    PubMed

    Liu, Mingxian; Dai, Libing; Shi, Huizhe; Xiong, Sheng; Zhou, Changren

    2015-04-01

    In this study, a series of alginate/halloysite nanotube (HNTs) composite scaffolds were prepared by solution-mixing and freeze-drying method. HNTs are incorporated into alginate to improve both the mechanical and cell-attachment properties of the scaffolds. The interfacial interactions between alginate and HNTs were confirmed by the atomic force microscope (AFM), transmission electron microscope (TEM) and FTIR spectroscopy. The mechanical, morphological, and physico-chemical properties of the composite scaffolds were investigated. The composite scaffolds exhibit significant enhancement in compressive strength and compressive modulus compared with pure alginate scaffold both in dry and wet states. A well-interconnected porous structure with size in the range of 100-200μm and over 96% porosity is found in the composite scaffolds. X-ray diffraction (XRD) result shows that HNTs are uniformly dispersed and partly oriented in the composite scaffolds. The incorporation of HNTs leads to increase in the scaffold density and decrease in the water swelling ratio of alginate. HNTs improve the stability of alginate scaffolds against enzymatic degradation in PBS solution. Thermogravimetrica analysis (TGA) shows that HNTs can improve the thermal stability of the alginate. The mouse fibroblast cells display better attachment to the alginate/HNT composite than those to the pure alginate, suggesting the good cytocompatibility of the composite scaffolds. Alginate/HNT composite scaffolds exhibit great potential for applications in tissue engineering. PMID:25686999

  4. Three-dimensional electrospun polycaprolactone (PCL)/alginate hybrid composite scaffolds.

    PubMed

    Kim, Min Seong; Kim, GeunHyung

    2014-12-19

    Micro/nanofibrous scaffolds have been used widely in biomedical applications because the micro/nano-scale fibres resemble natural extracellular matrix and the high surface-to-volume ratio encourages cellular activities (attachment and proliferation). However, poor mechanical properties, low controllability of various shapes and difficulties in obtaining controllable pore structure have been obstacles to their use in hard-tissue regeneration. To overcome these shortcomings, we suggest a new composite system, which uses a combination method of wet electrospinning, rapid prototyping and a physical punching process. Using the process, we obtained polycaprolactone (PCL)/alginate composite scaffolds, consisting of electrospun PCL/alginate fibres and micro-sized PCL struts, with mean pore sizes of 821 ± 55 μm. To show the feasibility of the scaffolds for hard-tissue regeneration, the scaffolds were assessed not only for physical properties, including hydrophilicity, water absorption, and tensile and compressive strength, but also in vitro cellular responses (cell viability and proliferation) and osteogenic differentiation (alkaline phosphatase (ALP) activity, and mineralisation) by culturing with pre-osteoblasts (MC3T3-E1 cells). With the reinforcing micro-sized PCL struts, the elastic modulus of the PCL/alginate scaffold was significantly improved versus a pure PCL scaffold. Additionally, due to the alginate component in the fibrous scaffold, they showed significantly enhanced hydrophilic behaviour, water absorption (∼8-fold) and significant biological activities (∼1.6-fold for cell viability at 7 days, ∼2.3-fold for ALP activity at 14 days and ∼6.4-fold for calcium mineralisation at 14 days) compared with those of a pure PCL fibrous scaffold.

  5. Hydroxyapatite-doped alginate beads as scaffolds for the osteoblastic differentiation of mesenchymal stem cells.

    PubMed

    Wang, Martha O; Bracaglia, Laura; Thompson, Joshua A; Fisher, John P

    2016-09-01

    This work investigates the role of an osteoblastic matrix component, hydroxyapatite (HA), in modular alginate scaffolds to support osteoblastic differentiation of human mesenchymal stem cells for the purpose of tissue engineered bone constructs. This system is first evaluated in a tubular perfusion bioreactor, which has been shown to improve osteoblastic differentiation over static culture conditions. HMSCs in alginate scaffolds that contain HA show increased osteoblastic gene expression compared to cells in pure alginate scaffolds, as well as significantly more matrix production and mineralization. The differentiated hMSCs and cell-laid matrix are ultimately evaluated in an in vivo site specific model. Implantation of these scaffolds with preformed matrix into the rat femoral condyle defects results in abundant bone growth and significant incorporation of the scaffold into the surrounding tissue. The developed mineralized matrix, induced in part by the HA component in the scaffold, could lead to increased tissue development in critically sized defects, and should be included in future implant strategies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2325-2333, 2016.

  6. Preparation of aminated chitosan/alginate scaffold containing halloysite nanotubes with improved cell attachment.

    PubMed

    Amir Afshar, Hamideh; Ghaee, Azadeh

    2016-10-20

    The chemical nature of biomaterials play important role in cell attachment, proliferation and migration in tissue engineering. Chitosan and alginate are biodegradable and biocompatible polymers used as scaffolds for various medical and clinical applications. Amine groups of chitosan scaffolds play an important role in cell attachment and water adsorption but also associate with alginate carboxyl groups via electrostatic interactions and hydrogen bonding, consequently the activity of amine groups in the scaffold decreases. In this study, chitosan/alginate/halloysite nanotube (HNTs) composite scaffolds were prepared using a freeze-drying method. Amine treatment on the scaffold occurred through chemical methods, which in turn caused the hydroxyl groups to be replaced with carboxyl groups in chitosan and alginate, after which a reaction between ethylenediamine, 1-ethyl-3,(3-dimethylaminopropyl) carbodiimide (EDC) and scaffold triggered the amine groups to connect to the carboxyl groups of chitosan and alginate. The chemical structure, morphology and mechanical properties of the composite scaffolds were investigated by FTIR, CHNS, SEM/EDS and compression tests. The electrostatic attraction and hydrogen bonding between chitosan, alginate and halloysite was confirmed by FTIR spectroscopy. Chitosan/alginate/halloysite scaffolds exhibit significant enhancement in compressive strength compared with chitosan/alginate scaffolds. CHNS and EDS perfectly illustrate that amine groups were effectively introduced in the aminated scaffold. The growth and cell attachment of L929 cells as well as the cytotoxicity of the scaffolds were investigated by SEM and Alamar Blue (AB). The results indicated that the aminated chitosan/alginate/halloysite scaffold has better cell growth and cell adherence in comparison to that of chitosan/alginate/halloysite samples. Aminated chitosan/alginate/halloysite composite scaffolds exhibit great potential for applications in tissue engineering, ideally in

  7. Preparation of aminated chitosan/alginate scaffold containing halloysite nanotubes with improved cell attachment.

    PubMed

    Amir Afshar, Hamideh; Ghaee, Azadeh

    2016-10-20

    The chemical nature of biomaterials play important role in cell attachment, proliferation and migration in tissue engineering. Chitosan and alginate are biodegradable and biocompatible polymers used as scaffolds for various medical and clinical applications. Amine groups of chitosan scaffolds play an important role in cell attachment and water adsorption but also associate with alginate carboxyl groups via electrostatic interactions and hydrogen bonding, consequently the activity of amine groups in the scaffold decreases. In this study, chitosan/alginate/halloysite nanotube (HNTs) composite scaffolds were prepared using a freeze-drying method. Amine treatment on the scaffold occurred through chemical methods, which in turn caused the hydroxyl groups to be replaced with carboxyl groups in chitosan and alginate, after which a reaction between ethylenediamine, 1-ethyl-3,(3-dimethylaminopropyl) carbodiimide (EDC) and scaffold triggered the amine groups to connect to the carboxyl groups of chitosan and alginate. The chemical structure, morphology and mechanical properties of the composite scaffolds were investigated by FTIR, CHNS, SEM/EDS and compression tests. The electrostatic attraction and hydrogen bonding between chitosan, alginate and halloysite was confirmed by FTIR spectroscopy. Chitosan/alginate/halloysite scaffolds exhibit significant enhancement in compressive strength compared with chitosan/alginate scaffolds. CHNS and EDS perfectly illustrate that amine groups were effectively introduced in the aminated scaffold. The growth and cell attachment of L929 cells as well as the cytotoxicity of the scaffolds were investigated by SEM and Alamar Blue (AB). The results indicated that the aminated chitosan/alginate/halloysite scaffold has better cell growth and cell adherence in comparison to that of chitosan/alginate/halloysite samples. Aminated chitosan/alginate/halloysite composite scaffolds exhibit great potential for applications in tissue engineering, ideally in

  8. Alginate/nanohydroxyapatite scaffolds with designed core/shell structures fabricated by 3D plotting and in situ mineralization for bone tissue engineering.

    PubMed

    Luo, Yongxiang; Lode, Anja; Wu, Chengtie; Chang, Jiang; Gelinsky, Michael

    2015-04-01

    Composite scaffolds, especially polymer/hydroxyapatite (HAP) composite scaffolds with predesigned structures, are promising materials for bone tissue engineering. Various methods including direct mixing of HAP powder with polymers or incubating polymer scaffolds in simulated body fluid for preparing polymer/HAP composite scaffolds are either uncontrolled or require long times of incubation. In this work, alginate/nano-HAP composite scaffolds with designed pore parameters and core/shell structures were fabricated using 3D plotting technique and in situ mineralization under mild conditions (at room temperature and without the use of any organic solvents). Light microscopy, scanning electron microscopy, microcomputer tomography, X-ray diffraction, and Fourier transform infrared spectroscopy were applied to characterize the fabricated scaffolds. Mechanical properties and protein delivery of the scaffolds were evaluated, as well as the cell response to the scaffolds by culturing human bone-marrow-derived mesenchymal stem cells (hBMSC). The obtained data indicate that this method is suitable to fabricate alginate/nano-HAP composite scaffolds with a layer of nano-HAP, coating the surface of the alginate strands homogeneously and completely. The surface mineralization enhanced the mechanical properties and improved the cell attachment and spreading, as well as supported sustaining protein release, compared to pure alginate scaffolds without nano-HAP shell layer. The results demonstrated that the method provides an interesting option for bone tissue engineering application.

  9. Optimization of keratin/alginate scaffold using RSM and its characterization for tissue engineering.

    PubMed

    Gupta, Pratima; Nayak, Kush Kumar

    2016-04-01

    The scaffold for tissue engineering was fabricated from a binary blend of keratin/alginate. The concentration and ratio of keratin and alginate was optimized by response surface methodology in a scaffold. The structural compatibility between keratin and alginate was examined by X-ray diffractometer and Fourier transforms infrared spectroscopy. Apparent porosity of the scaffold was calculated by Archimedes principles and its observed value of was found 96.25 ± 0.04%. The pore size of the scaffold was observed in the range between 10 and 200 μm. Tensile strength (0.33 ± 0.26 MPa) and percent of elongation at break (23.33 ± 2.52%) are the reported mechanical strength of the scaffold. Positive antimicrobial activity and in vitro degradation further confirms the fabrication of a scaffold required for tissue engineering application. PMID:26691383

  10. Optimization of keratin/alginate scaffold using RSM and its characterization for tissue engineering.

    PubMed

    Gupta, Pratima; Nayak, Kush Kumar

    2016-04-01

    The scaffold for tissue engineering was fabricated from a binary blend of keratin/alginate. The concentration and ratio of keratin and alginate was optimized by response surface methodology in a scaffold. The structural compatibility between keratin and alginate was examined by X-ray diffractometer and Fourier transforms infrared spectroscopy. Apparent porosity of the scaffold was calculated by Archimedes principles and its observed value of was found 96.25 ± 0.04%. The pore size of the scaffold was observed in the range between 10 and 200 μm. Tensile strength (0.33 ± 0.26 MPa) and percent of elongation at break (23.33 ± 2.52%) are the reported mechanical strength of the scaffold. Positive antimicrobial activity and in vitro degradation further confirms the fabrication of a scaffold required for tissue engineering application.

  11. Mechanically reinforced cell-laden scaffolds formed using alginate-based bioink printed onto the surface of a PCL/alginate mesh structure for regeneration of hard tissue.

    PubMed

    Kim, Yong Bok; Lee, Hyeongjin; Yang, Gi-Hoon; Choi, Chang Hyun; Lee, DaeWeon; Hwang, Heon; Jung, Won-Kyo; Yoon, Hyeon; Kim, Geun Hyung

    2016-01-01

    Cell-printing technology has provided a new paradigm for biofabrication, with potential to overcome several shortcomings of conventional scaffold-based tissue regeneration strategies via controlled delivery of various cell types in well-defined target regions. Here we describe a cell-printing method to obtain mechanically reinforced multi-layered cell-embedded scaffolds, formed of micron-scale poly(ε-caprolactone) (PCL)/alginate struts coated with alginate-based bioink. To compare the physical and cellular activities, we used a scaffold composed of pure alginate (without cells) coated PCL/alginate struts as a control. We systematically varied the ratio of alginate cross-linking agent, and determined the optimal cell-coating conditions to form the PCL/alginate struts. Following fabrication of the cell (MG63)-laden PCL/alginate scaffold, the bioactivity was evaluated in vitro. The laden cells exhibited a substantially more developed cytoskeleton compared with those on a control scaffold consisting of the same material composition. Based on these results, the printed cells exhibited a significantly more homogenous distribution within the scaffold compared with the control. Cell proliferation was determined via MTT assays at 1, 3, 7, and 14 days of culture, and the proliferation of the cell-printed scaffold was substantially in excess (∼2.4-fold) of that on the control. Furthermore, the osteogenic activity such as ALP was measured, and the cell-laden scaffold exhibited significantly greater activity (∼3.2-fold) compared with the control scaffold.

  12. Cell(MC3T3-E1)-printed poly(ϵ-caprolactone)/alginate hybrid scaffolds for tissue regeneration.

    PubMed

    Lee, Hyeongjin; Ahn, SeungHyun; Bonassar, Lawrence J; Kim, GeunHyung

    2013-01-25

    A new cell-printed scaffold consisting of poly(ϵ-caprolactone) (PCL) and cell-embedded alginate struts is designed. The PCL and alginate struts are stacked in an interdigitated pattern in successive layers to acquire a three-dimensional (3D) shape. The hybrid scaffold exhibits a two-phase structure consisting of cell (MC3T3-E1)-laden alginate struts able to support biological activity and PCL struts able to provide controllable mechanical support of the cell-laden alginate struts. The hybrid scaffolds exhibit an impressive increase in tensile modulus and maximum strength compared to pure alginate scaffolds. Laden cells are homogeneously distributed throughout the alginate struts and the entire scaffold, resulting in cell viability of approximately 84%.

  13. Mastoid obliteration using 3D PCL scaffold in combination with alginate and rhBMP-2.

    PubMed

    Jang, Chul Ho; Kim, Min Seong; Cho, Yong Beom; Jang, Yoon Seok; Kim, Geun Hyung

    2013-11-01

    Various materials, both biological and alloplastic, have been used for mastoid obliteration after canal wall-down mastoidectomy in chronic otitis media. The purpose of this study is to investigate the osteoinductive potential of PCL scaffolds in mastoid obliteration, and to test that osteoinductivity can be enhanced by coating PCL with alginate and rhBMP-2. The in vitro biocompatibilities of the scaffolds were examined using osteoblast-like cells (MG63). Cell-morphology and calcium deposition were assessed. Based on scanning electron microscope (SEM) images, the cells grew sporadically on the surfaces of the struts in the PCL scaffold, while the entire struts of the PCL/alginate/BMP-2 scaffold was covered with the cells. Furthermore, the PCL/alginate/BMP-2 scaffold showed significantly higher calcium deposition than the PCL/alginate scaffold. Micro-CT showed osteogenesis in the pores of the 3D PCL scaffold in the experimental group, compared to the control group. Confocal microscopic findings showed that the honeycomb appearance of the PCL structure remained in the control group (pure PCL), but significant amount of bone remodeling in the experimental group (PCL/alginate/BMP-2). Histomorphometric analysis showed that the experimental group demonstrated a significantly higher amount (p=0.014) of new bone formation with 50.2 ± 6.5% (mean ± SD), compared to 10.2 ± 3.5% for the control group. Based on these in vitro and in vivo results, the use of the PCL/alginate/BMP-2 scaffold seemed to be a promising technique for the mastoid obliteration.

  14. An additive manufacturing-based PCL-alginate-chondrocyte bioprinted scaffold for cartilage tissue engineering.

    PubMed

    Kundu, Joydip; Shim, Jin-Hyung; Jang, Jinah; Kim, Sung-Won; Cho, Dong-Woo

    2015-11-01

    Regenerative medicine is targeted to improve, restore or replace damaged tissues or organs using a combination of cells, materials and growth factors. Both tissue engineering and developmental biology currently deal with the process of tissue self-assembly and extracellular matrix (ECM) deposition. In this investigation, additive manufacturing (AM) with a multihead deposition system (MHDS) was used to fabricate three-dimensional (3D) cell-printed scaffolds using layer-by-layer (LBL) deposition of polycaprolactone (PCL) and chondrocyte cell-encapsulated alginate hydrogel. Appropriate cell dispensing conditions and optimum alginate concentrations for maintaining cell viability were determined. In vitro cell-based biochemical assays were performed to determine glycosaminoglycans (GAGs), DNA and total collagen contents from different PCL-alginate gel constructs. PCL-alginate gels containing transforming growth factor-β (TGFβ) showed higher ECM formation. The 3D cell-printed scaffolds of PCL-alginate gel were implanted in the dorsal subcutaneous spaces of female nude mice. Histochemical [Alcian blue and haematoxylin and eosin (H&E) staining] and immunohistochemical (type II collagen) analyses of the retrieved implants after 4 weeks revealed enhanced cartilage tissue and type II collagen fibril formation in the PCL-alginate gel (+TGFβ) hybrid scaffold. In conclusion, we present an innovative cell-printed scaffold for cartilage regeneration fabricated by an advanced bioprinting technology.

  15. Mechanically reinforced cell-laden scaffolds formed using alginate-based bioink printed onto the surface of a PCL/alginate mesh structure for regeneration of hard tissue.

    PubMed

    Kim, Yong Bok; Lee, Hyeongjin; Yang, Gi-Hoon; Choi, Chang Hyun; Lee, DaeWeon; Hwang, Heon; Jung, Won-Kyo; Yoon, Hyeon; Kim, Geun Hyung

    2016-01-01

    Cell-printing technology has provided a new paradigm for biofabrication, with potential to overcome several shortcomings of conventional scaffold-based tissue regeneration strategies via controlled delivery of various cell types in well-defined target regions. Here we describe a cell-printing method to obtain mechanically reinforced multi-layered cell-embedded scaffolds, formed of micron-scale poly(ε-caprolactone) (PCL)/alginate struts coated with alginate-based bioink. To compare the physical and cellular activities, we used a scaffold composed of pure alginate (without cells) coated PCL/alginate struts as a control. We systematically varied the ratio of alginate cross-linking agent, and determined the optimal cell-coating conditions to form the PCL/alginate struts. Following fabrication of the cell (MG63)-laden PCL/alginate scaffold, the bioactivity was evaluated in vitro. The laden cells exhibited a substantially more developed cytoskeleton compared with those on a control scaffold consisting of the same material composition. Based on these results, the printed cells exhibited a significantly more homogenous distribution within the scaffold compared with the control. Cell proliferation was determined via MTT assays at 1, 3, 7, and 14 days of culture, and the proliferation of the cell-printed scaffold was substantially in excess (∼2.4-fold) of that on the control. Furthermore, the osteogenic activity such as ALP was measured, and the cell-laden scaffold exhibited significantly greater activity (∼3.2-fold) compared with the control scaffold. PMID:26409783

  16. Injectable alginate/hydroxyapatite gel scaffold combined with gelatin microspheres for drug delivery and bone tissue engineering.

    PubMed

    Yan, Jingxuan; Miao, Yuting; Tan, Huaping; Zhou, Tianle; Ling, Zhonghua; Chen, Yong; Xing, Xiaodong; Hu, Xiaohong

    2016-06-01

    Injectable and biodegradable alginate-based composite gel scaffolds doubly integrated with hydroxyapatite (HAp) and gelatin microspheres (GMs) were cross-linked via in situ release of calcium cations. As triggers of calcium cations, CaCO3 and glucono-D-lactone (GDL) were fixed as a mass ratio of 1:1 to control pH value ranging from 6.8 to 7.2 during gelation. Synchronously, tetracycline hydrochloride (TH) was encapsulated into GMs to enhance bioactivity of composite gel scaffolds. The effects of HAp and GMs on characteristics of gel scaffolds, including pH value, gelation time, mechanical properties, swelling ratio, degradation behavior and drug release, were investigated. The results showed that HAp and GMs successfully improved mechanical properties of gel scaffolds at strain from 0.1 to 0.5, which stabilized the gel network and decreased weight loss, as well as swelling ratio and gelation time. TH could be released from this composite gel scaffold into the local microenvironment in a controlled fashion by the organic/inorganic hybrid of hydrogel network. Our results demonstrate that the HAp and GMs doubly integrated alginate-based gel scaffolds, especially the one with 6% (w/v) HAp and 5% (w/v) GMs, have suitable physical performance and bioactive properties, thus provide a potential opportunity to be used for bone tissue engineering. The potential application of this gel scaffold in bone tissue engineering was confirmed by encapsulation behavior of osteoblasts. In combination with TH, the gel scaffold exhibited beneficial effects on osteoblast activity, which suggested a promising future for local treatment of pathologies involving bone loss.

  17. Functional cell-laden alginate scaffolds consisting of core/shell struts for tissue regeneration.

    PubMed

    Ahn, SeungHyun; Lee, HyeongJin; Kim, GeunHyung

    2013-10-15

    We report an innovative cell-dispensing process using a three-axis robot system coupled with a micro-core/shell nozzle and an aerosol cross-linking process to achieve controlled mechanical properties and high cell viability of porous cell-laden alginate scaffolds. The scaffolds were fabricated into layer-by-layer struts, which were used to design the pore structure. The struts consisted of a core/shell region; a low weight fraction of alginate and cells (MC3T3-E1) was injected in the shell region to efficiently exchange nutrients and metabolic wastes, while a high weight fraction of alginate without cells was deposited in the core region to improve the mechanical properties of the cell-laden scaffold. After 10 days of cell culture, the cell viability (95%) in the shell region improved significantly compared to 70% for the cells homogeneously distributed in the struts, and the mechanical properties were enhanced from 1.4 to 15.7 kPa. Stained nuclei and F-actin images showed that the laden cells proliferated well on the functional hydrogel scaffold after 20 days of cell culture, indicating that the cells concentrated in the shell region of the struts survived and increased their metabolic functions during several incubation periods compared to the standard cell-laden scaffold. This innovative cell-dispensing technique represents a promising fabrication tool for obtaining bottom-up scaffolds for various tissue regenerations.

  18. Transplantation of Neural Stem Cells Cultured in Alginate Scaffold for Spinal Cord Injury in Rats

    PubMed Central

    Sharafkhah, Ali; Koohi-Hosseinabadi, Omid; Semsar-Kazerooni, Maryam

    2016-01-01

    Study Design This study investigated the effects of transplantation of alginate encapsulated neural stem cells (NSCs) on spinal cord injury in Sprague-Dawley male rats. The neurological functions were assessed for 6 weeks after transplantation along with a histological study and measurement of caspase-3 levels. Purpose The aim of this study was to discover whether NSCs cultured in alginate transplantation improve recovery from spinal cord injury. Overview of Literature Spinal cord injury is one of the leading causes of disability and it has no effective treatment. Spinal cord injury can also cause sensory impairment. With an impetus on using stem cells therapy in various central nervous system settings, there is an interest in using stem cells for addressing spinal cord injury. Neural stem cell is one type of stem cells that is able to differentiate to all three neural lineages and it shows promise in spinal injury treatment. Furthermore, a number of studies have shown that culturing NSCs in three-dimensional (3D) scaffolds like alginate could enhance neural differentiation. Methods The NSCs were isolated from 14-day-old rat embryos. The isolated NSCs were cultured in growth media containing basic fibroblast growth factor and endothelial growth factor. The cells were characterized by differentiating to three neural lineages and they were cultured in an alginate scaffold. After 7 days the cells were encapsulated and transplanted in a rat model of spinal cord injury. Results Our data showed that culturing in an alginate 3D scaffold and transplantation of the NSCs could improve neurological outcome in a rat model of spinal cord injury. The inflammation scores and lesion sizes and also the activity of caspase-3 (for apoptosis evaluation) were less in encapsulated neural stem cell transplantation cases. Conclusions Transplantation of NSCs that were cultured in an alginate scaffold led to a better clinical and histological outcome for recovery from spinal cord injury in

  19. Copper-releasing, boron-containing bioactive glass-based scaffolds coated with alginate for bone tissue engineering.

    PubMed

    Erol, M M; Mouriňo, V; Newby, P; Chatzistavrou, X; Roether, J A; Hupa, L; Boccaccini, Aldo R

    2012-02-01

    The aim of this study was to synthesize and characterize new boron-containing bioactive glass-based scaffolds coated with alginate cross-linked with copper ions. A recently developed bioactive glass powder with nominal composition (wt.%) 65 SiO2, 15 CaO, 18.4 Na2O, 0.1 MgO and 1.5 B2O3 was fabricated as porous scaffolds by the foam replica method. Scaffolds were alginate coated by dipping them in alginate solution. Scanning electron microscopy investigations indicated that the alginate effectively attached on the surface of the three-dimensional scaffolds leading to a homogeneous coating. It was confirmed that the scaffold structure remained amorphous after the sintering process and that the alginate coating improved the scaffold bioactivity and mechanical properties. Copper release studies showed that the alginate-coated scaffolds allowed controlled release of copper ions. The novel copper-releasing composite scaffolds represent promising candidates for bone regeneration. PMID:22040685

  20. Development and characterization of novel porous 3D alginate-cockle shell powder nanobiocomposite bone scaffold.

    PubMed

    Bharatham, B Hemabarathy; Abu Bakar, Md Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

    2014-01-01

    A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects.

  1. An ice-templated, linearly aligned chitosan-alginate scaffold for neural tissue engineering.

    PubMed

    Francis, Nicola L; Hunger, Philipp M; Donius, Amalie E; Riblett, Benjamin W; Zavaliangos, Antonios; Wegst, Ulrike G K; Wheatley, Margaret A

    2013-12-01

    Several strategies have been investigated to enhance axonal regeneration after spinal cord injury, however, the resulting growth can be random and disorganized. Bioengineered scaffolds provide a physical substrate for guidance of regenerating axons towards their targets, and can be produced by freeze casting. This technique involves the controlled directional solidification of an aqueous solution or suspension, resulting in a linearly aligned porous structure caused by ice templating. In this study, freeze casting was used to fabricate porous chitosan-alginate (C/A) scaffolds with longitudinally oriented channels. Chick dorsal root ganglia explants adhered to and extended neurites through the scaffold in parallel alignment with the channel direction. Surface adsorption of a polycation and laminin promoted significantly longer neurite growth than the uncoated scaffold (poly-L-ornithine + Laminin = 793.2 ± 187.2 μm; poly-L-lysine + Laminin = 768.7 ± 241.2 μm; uncoated scaffold = 22.52 ± 50.14 μm) (P < 0.001). The elastic modulus of the hydrated scaffold was determined to be 5.08 ± 0.61 kPa, comparable to reported spinal cord values. The present data suggested that this C/A scaffold is a promising candidate for use as a nerve guidance scaffold, because of its ability to support neuronal attachment and the linearly aligned growth of DRG neurites.

  2. Low intensity pulse ultrasound stimulate chondrocytes growth in a 3-D alginate scaffold through improved porosity and permeability.

    PubMed

    Guo, Gepu; Lu, Lu; Ji, Hongfei; Ma, Yong; Dong, Rui; Tu, Juan; Guo, Xiasheng; Qiu, Yuanyuan; Wu, Junru; Zhang, Dong

    2015-04-01

    A 3-D scaffold culture system has been used to promote in producing functional chondrocytes for repairing damaged cartilage. In the present study, the low intensity pulse ultrasound (LIPUS) (P(-)=0, 0.055, 0.085 and 0.11 MPa) was applied to improve the porosity and permeability of a 3-D alginate scaffold which was beneficial for the nutrition supply and metabolism during cell growth in 3-D alginate scaffold. The porosity and permeability of the scaffold was quantitatively analyzed based on scanning electron microscopy examination and fluorescence image observation. The results suggest that, for the scaffold exposed to LIPUS, its porosity and permeability could be significantly enhanced by the increasing LIPUS amplitude, which might be induced by the microstreaming shear stress generated by ultrasound-driven microbubble oscillations. Furthermore, the assessments of cell proliferation and collagen II expression confirmed that chondrocytes growth could be effectively promoted in 3-D alginate scaffolds treated by LIPUS, because of the improved scaffold porosity and permeability might benefit cell growth space and nutrition supply. It should also be noticed that appropriate LIPUS driving parameters should be adapted to achieve optimized chondrocytes culture effect in 3-D alginate scaffold. PMID:25543661

  3. Low intensity pulse ultrasound stimulate chondrocytes growth in a 3-D alginate scaffold through improved porosity and permeability.

    PubMed

    Guo, Gepu; Lu, Lu; Ji, Hongfei; Ma, Yong; Dong, Rui; Tu, Juan; Guo, Xiasheng; Qiu, Yuanyuan; Wu, Junru; Zhang, Dong

    2015-04-01

    A 3-D scaffold culture system has been used to promote in producing functional chondrocytes for repairing damaged cartilage. In the present study, the low intensity pulse ultrasound (LIPUS) (P(-)=0, 0.055, 0.085 and 0.11 MPa) was applied to improve the porosity and permeability of a 3-D alginate scaffold which was beneficial for the nutrition supply and metabolism during cell growth in 3-D alginate scaffold. The porosity and permeability of the scaffold was quantitatively analyzed based on scanning electron microscopy examination and fluorescence image observation. The results suggest that, for the scaffold exposed to LIPUS, its porosity and permeability could be significantly enhanced by the increasing LIPUS amplitude, which might be induced by the microstreaming shear stress generated by ultrasound-driven microbubble oscillations. Furthermore, the assessments of cell proliferation and collagen II expression confirmed that chondrocytes growth could be effectively promoted in 3-D alginate scaffolds treated by LIPUS, because of the improved scaffold porosity and permeability might benefit cell growth space and nutrition supply. It should also be noticed that appropriate LIPUS driving parameters should be adapted to achieve optimized chondrocytes culture effect in 3-D alginate scaffold.

  4. Fabrication and characterization of novel nano-biocomposite scaffold of chitosan-gelatin-alginate-hydroxyapatite for bone tissue engineering.

    PubMed

    Sharma, Chhavi; Dinda, Amit Kumar; Potdar, Pravin D; Chou, Chia-Fu; Mishra, Narayan Chandra

    2016-07-01

    A novel nano-biocomposite scaffold was fabricated in bead form by applying simple foaming method, using a combination of natural polymers-chitosan, gelatin, alginate and a bioceramic-nano-hydroxyapatite (nHAp). This approach of combining nHAp with natural polymers to fabricate the composite scaffold, can provide good mechanical strength and biological property mimicking natural bone. Environmental scanning electron microscopy (ESEM) images of the nano-biocomposite scaffold revealed the presence of interconnected pores, mostly spread over the whole surface of the scaffold. The nHAp particulates have covered the surface of the composite matrix and made the surface of the scaffold rougher. The scaffold has a porosity of 82% with a mean pore size of 112±19.0μm. Swelling and degradation studies of the scaffold showed that the scaffold possesses excellent properties of hydrophilicity and biodegradability. Short term mechanical testing of the scaffold does not reveal any rupturing after agitation under physiological conditions, which is an indicative of good mechanical stability of the scaffold. In vitro cell culture studies by seeding osteoblast cells over the composite scaffold showed good cell viability, proliferation rate, adhesion and maintenance of osteoblastic phenotype as indicated by MTT assay, ESEM of cell-scaffold construct, histological staining and gene expression studies, respectively. Thus, it could be stated that the nano-biocomposite scaffold of chitosan-gelatin-alginate-nHAp has the paramount importance for applications in bone tissue-engineering in future regenerative therapies.

  5. In Situ Gelation for Cell Immobilization and Culture in Alginate Foam Scaffolds

    PubMed Central

    Markussen, Christine; Dornish, Michael; Heier-Baardson, Helene; Melvik, Jan Egil; Alsberg, Eben; Christensen, Bjørn E.

    2014-01-01

    Essential cellular functions are often lost under culture in traditional two-dimensional (2D) systems. Therefore, biologically more realistic three-dimensional (3D) cell culture systems are needed that provide mechanical and biochemical cues which may otherwise be unavailable in 2D. For the present study, an alginate-based hydrogel system was used in which cells in an alginate solution were seeded onto dried alginate foams. A uniform distribution of NIH:3T3 and NHIK 3025 cells entrapped within the foam was achieved by in situ gelation induced by calcium ions integrated in the foam. The seeding efficiency of the cells was about 100% for cells added in a seeding solution containing 0.1–1.0% alginate compared with 18% when seeded without alginate. The NHIK 3025 cells were allowed to proliferate and form multi-cellular structures inside the transparent gel that were later vital stained and evaluated by confocal microcopy. Gels were de-gelled at different time points to isolate the multi-cellular structures and to determine the spheroid growth rate. It was also demonstrated that the mechanical properties of the gel could largely be varied through selection of type and concentration of the applied alginate and by immersing the already gelled disks in solutions providing additional gel-forming ions. Cells can efficiently be incorporated into the gel, and single cells and multi-cellular structures that may be formed inside can be retrieved without influencing cell viability or contaminating the sample with enzymes. The data show that the current system may overcome some limitations of current 3D scaffolds such as cell retrieval and in situ cell staining and imaging. PMID:24125496

  6. In situ gelation for cell immobilization and culture in alginate foam scaffolds.

    PubMed

    Andersen, Therese; Markussen, Christine; Dornish, Michael; Heier-Baardson, Helene; Melvik, Jan Egil; Alsberg, Eben; Christensen, Bjørn E

    2014-02-01

    Essential cellular functions are often lost under culture in traditional two-dimensional (2D) systems. Therefore, biologically more realistic three-dimensional (3D) cell culture systems are needed that provide mechanical and biochemical cues which may otherwise be unavailable in 2D. For the present study, an alginate-based hydrogel system was used in which cells in an alginate solution were seeded onto dried alginate foams. A uniform distribution of NIH:3T3 and NHIK 3025 cells entrapped within the foam was achieved by in situ gelation induced by calcium ions integrated in the foam. The seeding efficiency of the cells was about 100% for cells added in a seeding solution containing 0.1-1.0% alginate compared with 18% when seeded without alginate. The NHIK 3025 cells were allowed to proliferate and form multi-cellular structures inside the transparent gel that were later vital stained and evaluated by confocal microscopy. Gels were de-gelled at different time points to isolate the multi-cellular structures and to determine the spheroid growth rate. It was also demonstrated that the mechanical properties of the gel could largely be varied through selection of type and concentration of the applied alginate and by immersing the already gelled disks in solutions providing additional gel-forming ions. Cells can efficiently be incorporated into the gel, and single cells and multi-cellular structures that may be formed inside can be retrieved without influencing cell viability or contaminating the sample with enzymes. The data show that the current system may overcome some limitations of current 3D scaffolds such as cell retrieval and in situ cell staining and imaging.

  7. Proliferation and osteogenic differentiation of human bone marrow stromal cells on alginate-gelatine-hydroxyapatite scaffolds with anisotropic pore structure.

    PubMed

    Bernhardt, A; Despang, F; Lode, A; Demmler, A; Hanke, T; Gelinsky, M

    2009-01-01

    Porous mineralized scaffolds are required for various applications in bone engineering. In particular, tube-like pores with controlled orientation inside the scaffold may support homogeneous cell seeding as well as sufficient nutrient supply and may facilitate blood vessel ingrowth. Scaffolds with parallely orientated tube-like pores were generated by diffusion-controlled ionotropic gelation of alginate. Incorporation of hydroxyapatite (HA) during the gelation process yielded stable scaffolds with an average pore diameter of approximately 90 microm. To evaluate the potential use of alginate-gelatine-HA scaffolds for bone tissue engineering, in vitro tests with human bone marrow stromal cells (hBMSCs) were carried out. We analysed biocompatibility and cell penetration into the capillary pores by microscopic methods. hBMSCs were also cultivated on alginate-gelatine-HA scaffolds for 3 weeks in the presence and absence of osteogenic supplements. We studied proliferation and osteogenic differentiation in terms of total lactate dehydrogenase (LDH) activity, DNA content and alkaline phosphatase (ALP) activity and found a 10-14-fold increase of cell number after 2 weeks of cultivation, as well as an increase of specific ALP activity for osteogenic-induced hBMSCs. Furthermore, the expression of bone-related genes [ALP, bone sialoprotein II (BSPII)] was analysed. We found an increase of ALP as well as BSPII expression for osteogenic-induced hBMSCs on alginate-gelatin-HA scaffolds.

  8. A tunable silk-alginate hydrogel scaffold for stem cell culture and transplantation.

    PubMed

    Ziv, Keren; Nuhn, Harald; Ben-Haim, Yael; Sasportas, Laura S; Kempen, Paul J; Niedringhaus, Thomas P; Hrynyk, Michael; Sinclair, Robert; Barron, Annelise E; Gambhir, Sanjiv S

    2014-04-01

    One of the major challenges in regenerative medicine is the ability to recreate the stem cell niche, which is defined by its signaling molecules, the creation of cytokine gradients, and the modulation of matrix stiffness. A wide range of scaffolds has been developed in order to recapitulate the stem cell niche, among them hydrogels. This paper reports the development of a new silk-alginate based hydrogel with a focus on stem cell culture. This biocomposite allows to fine tune its elasticity during cell culture, addressing the importance of mechanotransduction during stem cell differentiation. The silk-alginate scaffold promotes adherence of mouse embryonic stem cells and cell survival upon transplantation. In addition, it has tunable stiffness as function of the silk-alginate ratio and the concentration of crosslinker--a characteristic that is very hard to accomplish in current hydrogels. The hydrogel and the presented results represents key steps on the way of creating artificial stem cell niche, opening up new paths in regenerative medicine. PMID:24484675

  9. Composite ECM-alginate microfibers produced by microfluidics as scaffolds with biomineralization potential.

    PubMed

    Angelozzi, Marco; Miotto, Martina; Penolazzi, Letizia; Mazzitelli, Stefania; Keane, Timothy; Badylak, Stephen F; Piva, Roberta; Nastruzzi, Claudio

    2015-11-01

    A novel approach to produce artificial bone composites (microfibers) with distinctive features mimicking natural tissue was investigated. Currently proposed inorganic materials (e.g. apatite matrixes) lack self-assembly and thereby limit interactions between cells and the material. The present work investigates the feasibility of creating "bio-inspired materials" specifically designed to overcome certain limitations inherent to current biomaterials. We examined the dimensions, morphology, and constitutive features of a composite hydrogel which combined an alginate based microfiber with a gelatin solution or a particulate form of urinary bladder matrix (UBM). The effectiveness of the composite microfibers to induce and modulate osteoblastic differentiation in three-dimensional (3D) scaffolds without altering the viability and morphological characteristics of the cells was investigated. The present study describes a novel alginate microfiber production method with the use of microfluidics. The microfluidic procedure allowed for precise tuning of microfibers which resulted in enhanced viability and function of embedded cells.

  10. Fish collagen/alginate/chitooligosaccharides integrated scaffold for skin tissue regeneration application.

    PubMed

    Chandika, Pathum; Ko, Seok-Chun; Oh, Gun-Woo; Heo, Seong-Yeong; Nguyen, Van-Tinh; Jeon, You-Jin; Lee, Bonggi; Jang, Chul Ho; Kim, GeunHyung; Park, Won Sun; Chang, Wonseok; Choi, Il-Whan; Jung, Won-Kyo

    2015-11-01

    An emerging paradigm in wound healing techniques is that a tissue-engineered skin substitute offers an alternative approach to create functional skin tissue. Here we developed a fish collagen/alginate (FCA) sponge scaffold that was functionalized by different molecular weights of chitooligosaccharides (COSs) with the use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as a cross-linking agent. The effects of cross-linking were analyzed by Fourier transform infrared spectroscopy. The results indicate that the homogeneous materials blending and cross-linking intensity were dependent on the molecular weights of COSs. The highly interconnected porous architecture with 160-260μm pore size and over 90% porosity and COS's MW driven swelling and retention capacity, tensile property and in vitro biodegradation behavior guaranteed the FCA/COS scaffolds for skin tissue engineering application. Further improvement of these properties enhanced the cytocompatibility of all the scaffolds, especially the scaffolds containing COSs with MW in the range of 1-3kDa (FCA/COS1) showed the best cytocompatibility. These physicochemical, mechanical, and biological properties suggest that the FCA/COS1 scaffold is a superior candidate that can be used for skin tissue regeneration.

  11. Fish collagen/alginate/chitooligosaccharides integrated scaffold for skin tissue regeneration application.

    PubMed

    Chandika, Pathum; Ko, Seok-Chun; Oh, Gun-Woo; Heo, Seong-Yeong; Nguyen, Van-Tinh; Jeon, You-Jin; Lee, Bonggi; Jang, Chul Ho; Kim, GeunHyung; Park, Won Sun; Chang, Wonseok; Choi, Il-Whan; Jung, Won-Kyo

    2015-11-01

    An emerging paradigm in wound healing techniques is that a tissue-engineered skin substitute offers an alternative approach to create functional skin tissue. Here we developed a fish collagen/alginate (FCA) sponge scaffold that was functionalized by different molecular weights of chitooligosaccharides (COSs) with the use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as a cross-linking agent. The effects of cross-linking were analyzed by Fourier transform infrared spectroscopy. The results indicate that the homogeneous materials blending and cross-linking intensity were dependent on the molecular weights of COSs. The highly interconnected porous architecture with 160-260μm pore size and over 90% porosity and COS's MW driven swelling and retention capacity, tensile property and in vitro biodegradation behavior guaranteed the FCA/COS scaffolds for skin tissue engineering application. Further improvement of these properties enhanced the cytocompatibility of all the scaffolds, especially the scaffolds containing COSs with MW in the range of 1-3kDa (FCA/COS1) showed the best cytocompatibility. These physicochemical, mechanical, and biological properties suggest that the FCA/COS1 scaffold is a superior candidate that can be used for skin tissue regeneration. PMID:26306410

  12. Design and Fabrication of a Biodegradable, Covalently Crosslinked Shape-Memory Alginate Scaffold for Cell and Growth Factor Delivery

    PubMed Central

    Wang, Lin; Shansky, Janet; Borselli, Cristina; Mooney, David

    2012-01-01

    The successful use of transplanted cells and/or growth factors for tissue repair is limited by a significant cell loss and/or rapid growth factor diffusion soon after implantation. Highly porous alginate scaffolds formed with covalent crosslinking have been used to improve cell survival and growth factor release kinetics, but require open-wound surgical procedures for insertion and have not previously been designed to readily degrade in vivo. In this study, a biodegradable, partially crosslinked alginate scaffold with shape-memory properties was fabricated for minimally invasive surgical applications. A mixture of high and low molecular weight partially oxidized alginate modified with RGD peptides was covalently crosslinked using carbodiimide chemistry. The scaffold was compressible 11-fold and returned to its original shape when rehydrated. Scaffold degradation properties in vitro indicated ∼85% mass loss by 28 days. The greater than 90% porous scaffolds released the recombinant growth factor insulin-like growth factor-1 over several days in vitro and allowed skeletal muscle cell survival, proliferation, and migration from the scaffold over a 28-day period. The compressible scaffold thus has the potential to be delivered by a minimally invasive technique, and when rehydrated in vivo with cells and/or growth factors, could serve as a temporary delivery vehicle for tissue repair. PMID:22646518

  13. Enhancing cell migration in shape-memory alginate-collagen composite scaffolds: In vitro and ex vivo assessment for intervertebral disc repair.

    PubMed

    Guillaume, Olivier; Naqvi, Syeda Masooma; Lennon, Kerri; Buckley, Conor Timothy

    2015-04-01

    Lower lumbar disc disorders pose a significant problem in an aging society with substantial socioeconomic consequences. Both inner tissue (nucleus pulposus) and outer tissue (annulus fibrosus) of the intervertebral disc are affected by such debilitating disorders and can lead to disc herniation and lower back pain. In this study, we developed an alginate-collagen composite porous scaffold with shape-memory properties to fill defects occurring in annulus fibrosus tissue of degenerated intervertebral discs, which has the potential to be administered using minimal invasive surgery. In the first part of this work, we assessed how collagen incorporation on preformed alginate scaffolds influences the physical properties of the final composite scaffold. We also evaluated the ability of annulus fibrosus cells to attach, migrate, and proliferate on the composite alginate-collagen scaffolds compared to control scaffolds (alginate only). In vitro experiments, performed in intervertebral disc-like microenvironmental conditions (low glucose and low oxygen concentrations), revealed that for alginate only scaffolds, annulus fibrosus cells agglomerated in clusters with limited infiltration and migration capacity. In comparison, for alginate-collagen scaffolds, annulus fibrosus cells readily attached and colonized constructs, while preserving their typical fibroblastic-like cell morphology with spreading behavior and intense cytoskeleton expression. In a second part of this study, we investigated the effects of alginate-collagen scaffold when seeded with bone marrow derived mesenchymal stem cells. In vitro, we observed that alginate-collagen porous scaffolds supported cell proliferation and extracellular matrix deposition (collagen type I), with secretion amplified by the local release of transforming growth factor-β3. In addition, when cultured in ex vivo organ defect model, alginate-collagen scaffolds maintained viability of transplanted mesenchymal stem cells for up to 5

  14. Delivery of Alginate Scaffold Releasing Two Trophic Factors for Spinal Cord Injury Repair

    PubMed Central

    Grulova, I.; Slovinska, L.; Blaško, J.; Devaux, S.; Wisztorski, M.; Salzet, M.; Fournier, I.; Kryukov, O.; Cohen, S.; Cizkova, D.

    2015-01-01

    Spinal cord injury (SCI) has been implicated in neural cell loss and consequently functional motor and sensory impairment. In this study, we propose an alginate -based neurobridge enriched with/without trophic growth factors (GFs) that can be utilized as a therapeutic approach for spinal cord repair. The bioavailability of key GFs, such as Epidermal Growth factor (EGF) and basic Fibroblast Growth Factor (bFGF) released from injected alginate biomaterial to the central lesion site significantly enhanced the sparing of spinal cord tissue and increased the number of surviving neurons (choline acetyltransferase positive motoneurons) and sensory fibres. In addition, we document enhanced outgrowth of corticospinal tract axons and presence of blood vessels at the central lesion. Tissue proteomics was performed at 3, 7 and 10 days after SCI in rats indicated the presence of anti-inflammatory factors in segments above the central lesion site, whereas in segments below, neurite outgrowth factors, inflammatory cytokines and chondroitin sulfate proteoglycan of the lectican protein family were overexpressed. Collectively, based on our data, we confirm that functional recovery was significantly improved in SCI groups receiving alginate scaffold with affinity-bound growth factors (ALG +GFs), compared to SCI animals without biomaterial treatment. PMID:26348665

  15. Spray-spinning: a novel method for making alginate/chitosan fibrous scaffold.

    PubMed

    Wang, Jian-Zheng; Huang, Xiao-Bo; Xiao, Jing; Li, Nan; Yu, Wei-Ting; Wang, Wei; Xie, Wei-Yang; Ma, Xiao-Jun; Teng, Ying-Li

    2010-02-01

    The subject of our investigations was the process of obtaining alginate/chitosan polyelectrolyte complex (PEC) fibers. In this study, a novel method named "spray-spinning" was developed for the making of these hybrid fibers. In spray-spinning, a chitosan solution was sprayed into a flowing sodium alginate solution and sheared into streamlines. The elongated streamlines subsequently transformed into alginate/chitosan PEC fibers. Average diameter of the fibers increased with the increasing of chitosan concentration used in spinning. The fibers showed a high water-absorbability of about 45 folds of water to their dry weight and retained their integrity after incubation in Minimum Essential Medium (MEM) for up to 30 days. In vitro co-culture experiments indicated that the fibers could support the three-dimensional growth of HepG2 cells and did not display any cyto-toxicity. Moreover, in vivo implanting experiments indicated that the connective tissue cells infiltrated into the implanted fibrous scaffolds in 3 weeks after surgery. These results demonstrated the potential applications of the as-spun fibers in regenerative medicine and tissue engineering. PMID:19756966

  16. A tunable silk-alginate hydrogel scaffold for stem cell culture and transplantation

    PubMed Central

    Ziv, Keren; Nuhn, Harald; Ben-Haim, Yael; Sasportas, Laura S.; Kempen, Paul J.; Niedringhaus, Thomas P.; Hrynyk, Michael; Sinclair, Robert; Barron, Annelise E.; Gambhir, Sanjiv S.

    2014-01-01

    One of the major challenges in regenerative medicine is the ability to recreate the stem cell niche, which is defined by its signaling molecules, the creation of cytokine gradients, and the modulation of matrix stiffness. A wide range of scaffolds has been developed in order to recapitulate the stem cell niche, among them hydrogels. This paper reports the development of a new silk-alginate based hydrogel with a focus on stem cell culture. This biocomposite allows to fine tune its elasticity during cell culture, addressing the importance of mechanotransduction during stem cell differentiation. The silk-alginate scaffold promotes adherence of mouse embryonic stem cells and cell survival upon transplantation. In addition, it has tunable stiffness as function of the silk-alginte ratio and the concentration of crosslinker - a characteristic that is very hard to accomplish in current hydrogels. The hydrogel and the presented results represents key steps on the way of creating artificial stem cell niche, opening up new paths in regenerative medicine. PMID:24484675

  17. Development and characterization of novel porous 3D alginate-cockle shell powder nanobiocomposite bone scaffold.

    PubMed

    Bharatham, B Hemabarathy; Abu Bakar, Md Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

    2014-01-01

    A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects. PMID:25110655

  18. Structural modification and characterization of bacterial cellulose-alginate composite scaffolds for tissue engineering.

    PubMed

    Kirdponpattara, Suchata; Khamkeaw, Arnon; Sanchavanakit, Neeracha; Pavasant, Prasit; Phisalaphong, Muenduen

    2015-11-01

    A novel bacterial cellulose-alginate composite scaffold (N-BCA) was fabricated by freeze drying and subsequent crosslinking with Ca(2+). The N-BCA then underwent a second freeze drying step to remove water without altering the physical structure. A stable structure of N-BCA with open and highly interconnected pores in the range of 90-160 μm was constructed. The N-BCA was stable in both water and PBS. The swelling ability of N-BCA in water was approximately 50 times its weight, which was about 6.5 times that of the freeze dried bacterial cellulose pellicles. N-BCA demonstrated no cytotoxicity against L929 mouse fibroblast cells. For long-term culture, N-BCA supported attachment, spreading, and proliferation of human gingival fibroblast (GF) on the surface. However, under static conditions, the cell migration and growth inside the scaffold were limited. Because of its biocompatibility and open macroporous structure, N-BCA could potentially be used as a scaffold for tissue engineering. PMID:26256335

  19. Structural modification and characterization of bacterial cellulose-alginate composite scaffolds for tissue engineering.

    PubMed

    Kirdponpattara, Suchata; Khamkeaw, Arnon; Sanchavanakit, Neeracha; Pavasant, Prasit; Phisalaphong, Muenduen

    2015-11-01

    A novel bacterial cellulose-alginate composite scaffold (N-BCA) was fabricated by freeze drying and subsequent crosslinking with Ca(2+). The N-BCA then underwent a second freeze drying step to remove water without altering the physical structure. A stable structure of N-BCA with open and highly interconnected pores in the range of 90-160 μm was constructed. The N-BCA was stable in both water and PBS. The swelling ability of N-BCA in water was approximately 50 times its weight, which was about 6.5 times that of the freeze dried bacterial cellulose pellicles. N-BCA demonstrated no cytotoxicity against L929 mouse fibroblast cells. For long-term culture, N-BCA supported attachment, spreading, and proliferation of human gingival fibroblast (GF) on the surface. However, under static conditions, the cell migration and growth inside the scaffold were limited. Because of its biocompatibility and open macroporous structure, N-BCA could potentially be used as a scaffold for tissue engineering.

  20. Calcium/Cobalt Alginate Beads as Functional Scaffolds for Cartilage Tissue Engineering

    PubMed Central

    Focaroli, Stefano; Teti, Gabriella; Salvatore, Viviana; Orienti, Isabella; Falconi, Mirella

    2016-01-01

    Articular cartilage is a highly organized tissue with complex biomechanical properties. However, injuries to the cartilage usually lead to numerous health concerns and often culminate in disabling symptoms, due to the poor intrinsic capacity of this tissue for self-healing. Although various approaches are proposed for the regeneration of cartilage, its repair still represents an enormous challenge for orthopedic surgeons. The field of tissue engineering currently offers some of the most promising strategies for cartilage restoration, in which assorted biomaterials and cell-based therapies are combined to develop new therapeutic regimens for tissue replacement. The current study describes the in vitro behavior of human adipose-derived mesenchymal stem cells (hADSCs) encapsulated within calcium/cobalt (Ca/Co) alginate beads. These novel chondrogenesis-promoting scaffolds take advantage of the synergy between the alginate matrix and Co+2 ions, without employing costly growth factors (e.g., transforming growth factor betas (TGF-βs) or bone morphogenetic proteins (BMPs)) to direct hADSC differentiation into cartilage-producing chondrocytes. PMID:27057167

  1. Comparing different methods to fix and to dehydrate cells on alginate hydrogel scaffolds using scanning electron microscopy.

    PubMed

    Santana, Bianca Palma; Nedel, Fernanda; Perelló Ferrúa, Camila; Marques e Silva, Ricardo; da Silva, Adriana Fernandes; Demarco, Flávio Fernando; Lenin Villarreal Carreño, Neftali

    2015-07-01

    Scanning electron microscopy (SEM) is commonly used in the analysis of scaffolds morphology, as well as cell attachment, morphology and spreading on to the scaffolds. However, so far a specific methodology to prepare the alginate hydrogel (AH) scaffolds for SEM analysis has not been evaluated. This study compared different methods to fix/dehydrate cells in AH scaffolds for SEM analysis. AH scaffolds were prepared and seeded with NIH/3T3 cell line; fixed with glutaraldehyde, osmium tetroxide, or the freeze drying method and analyzed by SEM. Results demonstrated that the freeze dried method interferes less with cell morphology and density, and preserves the scaffolds structure. The fixation with glutaraldehyde did not affect cells morphology and density; however, the scaffolds morphology was affected in some level. The fixation with osmium tetroxide interfered in the natural structure of cells and scaffold. In conclusion the freeze drying and glutaraldehyde are suitable methods for cell fixation in AH scaffold for SEM, although scaffolds structure seems to be affected by glutaraldehyde.

  2. Comparing different methods to fix and to dehydrate cells on alginate hydrogel scaffolds using scanning electron microscopy.

    PubMed

    Santana, Bianca Palma; Nedel, Fernanda; Perelló Ferrúa, Camila; Marques e Silva, Ricardo; da Silva, Adriana Fernandes; Demarco, Flávio Fernando; Lenin Villarreal Carreño, Neftali

    2015-07-01

    Scanning electron microscopy (SEM) is commonly used in the analysis of scaffolds morphology, as well as cell attachment, morphology and spreading on to the scaffolds. However, so far a specific methodology to prepare the alginate hydrogel (AH) scaffolds for SEM analysis has not been evaluated. This study compared different methods to fix/dehydrate cells in AH scaffolds for SEM analysis. AH scaffolds were prepared and seeded with NIH/3T3 cell line; fixed with glutaraldehyde, osmium tetroxide, or the freeze drying method and analyzed by SEM. Results demonstrated that the freeze dried method interferes less with cell morphology and density, and preserves the scaffolds structure. The fixation with glutaraldehyde did not affect cells morphology and density; however, the scaffolds morphology was affected in some level. The fixation with osmium tetroxide interfered in the natural structure of cells and scaffold. In conclusion the freeze drying and glutaraldehyde are suitable methods for cell fixation in AH scaffold for SEM, although scaffolds structure seems to be affected by glutaraldehyde. PMID:25871651

  3. Biodegradable photo-crosslinked alginate nanofibre scaffolds with tuneable physical properties, cell adhesivity and growth factor release.

    PubMed

    Jeong, Sung In; Jeon, Oju; Krebs, Melissa D; Hill, Michael C; Alsberg, Eben

    2012-01-01

    Nanofibrous scaffolds are of interest in tissue engineering due to their high surface area to volume ratio, interconnected pores, and architectural similarity to the native extracellular matrix. Our laboratory recently developed a biodegradable, photo-crosslinkable alginate biopolymer. Here, we show the capacity of the material to be electrospun into a nanofibrous matrix, and the ability to enhance cell adhesion and proliferation on these matrices by covalent modification with cell adhesion peptides. Additionally, the potential of covalently incorporating heparin into the hydrogels during the photopolymerisation process to sustain the release of a heparin binding growth factor via affinity interactions was demonstrated. Electrospun photo-crosslinkable alginate nanofibrous scaffolds endowed with cell adhesion ligands and controlled delivery of growth factors may allow for improved regulation of cell behaviour for regenerative medicine. PMID:23070945

  4. BIODEGRADABLE PHOTO-CROSSLINKED ALGINATE NANOFIBRE SCAFFOLDS WITH TUNEABLE PHYSICAL PROPERTIES, CELL ADHESIVITY AND GROWTH FACTOR RELEASE

    PubMed Central

    Jeong, Sung In; Jeon, Oju; Krebs, Melissa D.; Hill, Michael C.; Alsberg, Eben

    2012-01-01

    Nanofibrous scaffolds are of interest in tissue engineering due to their high surface area to volume ratio, interconnected pores, and architectural similarity to the native extracellular matrix. Our laboratory recently developed a biodegradable, photo-crosslinkable alginate biopolymer. Here, we show the capacity of the material to be electrospun into a nanofibrous matrix, and the ability to enhance cell adhesion and proliferation on these matrices by covalent modification with cell adhesion peptides. Additionally, the potential of covalently incorporating heparin into the hydrogels during the photopolymerisation process to sustain the release of a heparin binding growth factor via affinity interactions was demonstrated. Electrospun photo-crosslinkable alginate nanofibrous scaffolds endowed with cell adhesion ligands and controlled delivery of growth factors may allow for improved regulation of cell behaviour for regenerative medicine. PMID:23070945

  5. Proliferation and enrichment of CD133+ glioblastoma cancer stem cells on 3D chitosan-alginate scaffolds

    PubMed Central

    Kievit, Forrest M.; Florczyk, Stephen J.; Leung, Matthew C.; Wang, Kui; Wu, Jennifer D.; Silber, John R.; Ellenbogen, Richard G.; Lee, Jerry S.H.; Zhang, Miqin

    2014-01-01

    Emerging evidence implicates cancer stem cells (CSCs) as primary determinants of the clinical behavior of human cancers, representing an ideal target for next-generation anticancer therapies. However CSCs are difficult to propagate in vitro, severely limiting the study of CSC biology and drug development. Here we report that growing cells from glioblastoma (GBM) cell lines on three dimensional (3D) porous chitosan-alginate (CA) scaffolds dramatically promotes the proliferation and enrichment of cells possessing the hallmarks of CSCs. CA scaffold-grown cells were found more tumorigenic in nude mouse xenografts than cells grown from monolayers. Growing in CA scaffolds rapidly promoted expression of genes involved in the epithelial-to-mesenchymal transition that has been implicated in the genesis of CSCs. Our results indicate that CA scaffolds have utility as a simple and inexpensive means to cultivate CSCs in vitro in support of studies to understand CSC biology and develop more effective anti-cancer therapies. PMID:25109438

  6. Human hepatoma cell lines on gas foaming templated alginate scaffolds for in vitro drug-drug interaction and metabolism studies.

    PubMed

    Stampella, A; Rizzitelli, G; Donati, F; Mazzarino, M; de la Torre, X; Botrè, F; Giardi, M F; Dentini, M; Barbetta, A; Massimi, M

    2015-12-25

    Liver in vitro systems that allow reliable prediction of major human in vivo metabolic pathways have a significant impact in drug screening and drug metabolism research. In the present study, a novel porous scaffold composed of alginate was prepared by employing a gas-in-liquid foaming approach. Galactose residues were introduced on scaffold surfaces to promote cell adhesion and to enhance liver specific functions of the entrapped HepG2/C3A cells. Hepatoma cells in the gal-alginate scaffold showed higher levels of liver specific products (albumin and urea) and were more responsive to specific inducers (e.g. dexamethasone) and inhibitors (e.g. ketoconazole) of the CYP3A4 system than in conventional monolayer culture. HepG2/C3A cells were also more efficient in terms of rapid elimination of testosterone, used as a model substance, at rates comparable to those of in vivo excretion. In addition, an improvement in metabolism of testosterone, in terms of phase II metabolite formation, was also observed when the more differentiated HepaRG cells were used. Together the data suggest that hepatocyte/gas templated alginate-systems provide an innovative high throughput platform for in vitro drug metabolism and drug-drug interaction studies, with broad fields of application, and might provide a valid tool for minimizing animal use in preclinical testing of human relevance.

  7. Self-crosslinked oxidized alginate/gelatin hydrogel as injectable, adhesive biomimetic scaffolds for cartilage regeneration.

    PubMed

    Balakrishnan, Biji; Joshi, Nitin; Jayakrishnan, Athipettah; Banerjee, Rinti

    2014-08-01

    Biopolymeric hydrogels that mimic the properties of extracellular matrix have great potential in promoting cellular migration and proliferation for tissue regeneration. The authors reported earlier that rapidly gelling, biodegradable, injectable hydrogels can be prepared by self-crosslinking of periodate oxidized alginate and gelatin in the presence of borax, without using any toxic crosslinking agents. The present paper investigates the suitability of this hydrogel as a minimally invasive injectable, cell-attractive and adhesive scaffold for cartilage tissue engineering for the treatment of osteoarthritis. Time and frequency sweep rheology analysis confirmed gel formation within 20s. The hydrogel integrated well with the cartilage tissue, with a burst pressure of 70±3mmHg, indicating its adhesive nature. Hydrogel induced negligible inflammatory and oxidative stress responses, a prerequisite for the management and treatment of osteoarthritis. Scanning electron microscopy images of primary murine chondrocytes encapsulated within the matrix revealed attachment of cells onto the hydrogel matrix. Chondrocytes demonstrated viability, proliferation and migration within the matrix, while maintaining their phenotype, as seen by expression of collagen type II and aggrecan, and functionality, as seen by enhanced glycosoaminoglycan (GAG) deposition with time. DNA content and GAG deposition of chondrocytes within the matrix can be tuned by incorporation of bioactive signaling molecules such as dexamethasone, chondroitin sulphate, platelet derived growth factor (PDGF-BB) and combination of these three agents. The results suggest that self-crosslinked oxidized alginate/gelatin hydrogel may be a promising injectable, cell-attracting adhesive matrix for neo-cartilage formation in the management and treatment of osteoarthritis. PMID:24811827

  8. Enhanced Healing of Rat Calvarial Defects with MSCs Loaded on BMP-2 Releasing Chitosan/Alginate/Hydroxyapatite Scaffolds

    PubMed Central

    He, Xiaoning; Liu, Yang; Yuan, Xue; Lu, Li

    2014-01-01

    In this study, we designed a chitosan/alginate/hydroxyapatite scaffold as a carrier for recombinant BMP-2 (CAH/B2), and evaluated the release kinetics of BMP-2. We evaluated the effect of the CAH/B2 scaffold on the viability and differentiation of bone marrow mesenchymal stem cells (MSCs) by scanning electron microscopy, MTS, ALP assay, alizarin-red staining and qRT-PCR. Moreover, MSCs were seeded on scaffolds and used in a 8 mm rat calvarial defect model. New bone formation was assessed by radiology, hematoxylin and eosin staining 12 weeks postoperatively. We found the release kinetics of BMP-2 from the CAH/B2 scaffold were delayed compared with those from collagen gel, which is widely used for BMP-2 delivery. The BMP-2 released from the scaffold increased MSC differentiation and did not show any cytotoxicity. MSCs exhibited greater ALP activity as well as stronger calcium mineral deposition, and the bone-related markers Col1α, osteopontin, and osteocalcin were upregulated. Analysis of in vivo bone formation showed that the CAH/B2 scaffold induced more bone formation than other groups. This study demonstrates that CAH/B2 scaffolds might be useful for delivering osteogenic BMP-2 protein and present a promising bone regeneration strategy. PMID:25084008

  9. The promotion of in vitro vessel-like organization of endothelial cells in magnetically responsive alginate scaffolds

    PubMed Central

    Sapir, Yulia; Cohen, Smadar; Friedman, Gary; Polyak, Boris

    2012-01-01

    One of the major challenges in engineering thick, complex tissues such as cardiac muscle, is the need to pre-vascularize the engineered tissue in vitro to enable its efficient integration with host tissue upon implantation. Herein, we explored new magnetic alginate composite scaffolds to provide means of physical stimulation to cells. Magnetite-impregnated alginate scaffolds seeded with aortic endothelial cells stimulated during the first 7 days out of a total 14 day experimental course showed significantly elevated metabolic activity during the stimulation period. Expression of proliferating cell nuclear antigen (PCNA) indicated that magnetically stimulated cells had a lower proliferation index as compared to the non-stimulated cells. This suggests that the elevated metabolic activity could instead be related to cell migration and re-organization. Immunostaining and confocal microscopy analyses supported this observation showing that on day 14 in magnetically stimulated scaffolds without supplementation of any growth factors, cellular vessel-like (loop) structures, known as indicators of vasculogenesis and angiogenesis were formed as compared to cell sheets or aggregates observed in the non-stimulated (control) scaffolds. This work is the first step in our understanding of how to accurately control cellular organization to form tissue engineered constructs, which together with additional molecular signals could lead to a creation of an efficient pre-vascularized tissue construct with potential applicability for transplantation. PMID:22417620

  10. The effect of an alginate carrier on bone formation in a hydroxyapatite scaffold.

    PubMed

    Coathup, Melanie J; Edwards, Thomas C; Samizadeh, Sorousheh; Lo, Wei-Jen; Blunn, Gordon W

    2016-10-01

    This study investigated the osteoconductive properties of a porous hydroxyapatite (HA) scaffold manufactured using a novel technique similar to the bread-making process, alone and in combination with an alginate polysaccharide fiber gel (HA/APFG putty) and autologous bone marrow aspirate (BMA). The hypothesis was that the HA/APFG putty would be as osteoconductive as granular HA and that the presence of BMA would further enhance bone formation in an ovine femoral condyle critical defect model. Thirty-six defects were created and either (1) porous HA granules, (2) HA/APFG putty, or (3) HA/APFG putty + BMA were implanted. After retrieval at 6 and 12 weeks, image analysis techniques were used to quantify bone apposition rates, new bone area, bone-HA scaffold contact, and implant resorption. At 6 weeks postsurgery, significantly lower bone apposition rates were observed in the HA/APFG putty group when compared to the HA (p = 0.014) and HA/APFG putty + BMA (p = 0.014) groups. At 12 weeks, significantly increased amounts of new bone formation were measured within the HA scaffold (33.56 ± 3.53%) when compared to both the HA/APFG putty (16.69 ± 2.7%; p = 0.043) and the defects containing HA/APFG putty + BMA (19.31 ± 3.8%; p = 0.043). The use of an APFG gel as a carrier for injectable CaP bone substitute materials delayed bone formation in this model compared to HA granules alone which enhanced bone formation especially within the interconnected smaller pores. Our results also showed that the addition of autologous BMA did not further enhance its osteoconductive properties. Further study is required to optimize the degradation rate of this APFG binding agent before using as a directly injectable material for repair of bone defect. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1328-1335, 2016.

  11. 3D Porous Calcium-Alginate Scaffolds Cell Culture System Improved Human Osteoblast Cell Clusters for Cell Therapy

    PubMed Central

    Chen, Ching-Yun; Ke, Cherng-Jyh; Yen, Ko-Chung; Hsieh, Hui-Chen; Sun, Jui-Sheng; Lin, Feng-Huei

    2015-01-01

    Age-related orthopedic disorders and bone defects have become a critical public health issue, and cell-based therapy is potentially a novel solution for issues surrounding bone tissue engineering and regenerative medicine. Long-term cultures of primary bone cells exhibit phenotypic and functional degeneration; therefore, culturing cells or tissues suitable for clinical use remain a challenge. A platform consisting of human osteoblasts (hOBs), calcium-alginate (Ca-Alginate) scaffolds, and a self-made bioreactor system was established for autologous transplantation of human osteoblast cell clusters. The Ca-Alginate scaffold facilitated the growth and differentiation of human bone cell clusters, and the functionally-closed process bioreactor system supplied the soluble nutrients and osteogenic signals required to maintain the cell viability. This system preserved the proliferative ability of cells and cell viability and up-regulated bone-related gene expression and biological apatite crystals formation. The bone-like tissue generated could be extracted by removal of calcium ions via ethylenediaminetetraacetic acid (EDTA) chelation, and exhibited a size suitable for injection. The described strategy could be used in therapeutic application and opens new avenues for surgical interventions to correct skeletal defects. PMID:25825603

  12. Preparation and characterization of nano-sized hydroxyapatite/alginate/chitosan composite scaffolds for bone tissue engineering.

    PubMed

    Kim, Hye-Lee; Jung, Gil-Yong; Yoon, Jun-Ho; Han, Jung-Suk; Park, Yoon-Jeong; Kim, Do-Gyoon; Zhang, Miqin; Kim, Dae-Joon

    2015-09-01

    The aim of this study was to develop chitosan composite scaffolds with high strength and controlled pore structures by homogenously dispersed nano-sized hydroxyapatite (nano-HAp) powders. In the fabrication of composite scaffolds, nano-HAp powders distributed in an alginate (AG) solution with a pH higher than 10 were mixed with a chitosan (CS) solution and then freeze dried. While the HAp content increased up to 70 wt.%, the compressive strength and the elastic modulus of the composite scaffolds significantly increased from 0.27 MPa and 4.42 MPa to 0.68 MPa and 13.35 MPa, respectively. Higher content of the HAp also helped develop more differentiation and mineralization of the MC3T3-E1 cells on the composite scaffolds. The uniform pore structure and the excellent mechanical properties of the HAp/CS composite scaffolds likely resulted from the use of the AG solution at pH 10 as a dispersant for the nano-HAp powders. PMID:26046263

  13. Automated quantitative characterization of alginate/hydroxyapatite bone tissue engineering scaffolds by means of micro-CT image analysis.

    PubMed

    Brun, Francesco; Turco, Gianluca; Accardo, Agostino; Paoletti, Sergio

    2011-12-01

    Accurate image acquisition techniques and analysis protocols for a reliable characterization of tissue engineering scaffolds are yet to be well defined. To this aim, the most promising imaging technique seems to be the X-ray computed microtomography (μ-CT). However critical issues of the analysis process deal with the representativeness of the selected Volume of Interest (VOI) and, most significantly, its segmentation. This article presents an image analysis protocol that computes a set of quantitative descriptors suitable for characterizing the morphology and the micro-architecture of alginate/hydroxyapatite bone tissue engineering scaffolds. Considering different VOIs extracted from different μ-CT datasets, an automated segmentation technique is suggested and compared against a manual segmentation. Variable sizes of VOIs are also considered in order to assess their representativeness. The resulting image analysis protocol is reproducible, parameter-free and it automatically provides accurate quantitative information in addition to the simple qualitative observation of the acquired images.

  14. Macro- and micro-designed chitosan-alginate scaffold architecture by three-dimensional printing and directional freezing.

    PubMed

    Reed, Stephanie; Lau, Grace; Delattre, Benjamin; Lopez, David Don; Tomsia, Antoni P; Wu, Benjamin M

    2016-01-07

    While many tissue-engineered constructs aim to treat cartilage defects, most involve chondrocyte or stem cell seeding on scaffolds. The clinical application of cell-based techniques is limited due to the cost of maintaining cellular constructs on the shelf, potential immune response to allogeneic cell lines, and autologous chondrocyte sources requiring biopsy from already diseased or injured, scarce tissue. An acellular scaffold that can induce endogenous influx and homogeneous distribution of native stem cells from bone marrow holds great promise for cartilage regeneration. This study aims to develop such an acellular scaffold using designed, channeled architecture that simultaneously models the native zones of articular cartilage and subchondral bone. Highly porous, hydrophilic chitosan-alginate (Ch-Al) scaffolds were fabricated in three-dimensionally printed (3DP) molds designed to create millimeter scale macro-channels. Different polymer preform casting techniques were employed to produce scaffolds from both negative and positive 3DP molds. Macro-channeled scaffolds improved cell suspension distribution and uptake overly randomly porous scaffolds, with a wicking volumetric flow rate of 445.6 ± 30.3 mm(3) s(-1) for aqueous solutions and 177 ± 16 mm(3) s(-1) for blood. Additionally, directional freezing was applied to Ch-Al scaffolds, resulting in lamellar pores measuring 300 μm and 50 μm on the long and short axes, thus creating micrometer scale micro-channels. After directionally freezing Ch-Al solution cast in 3DP molds, the combined macro- and micro-channeled scaffold architecture enhanced cell suspension uptake beyond either macro- or micro-channels alone, reaching a volumetric flow rate of 1782.1 ± 48 mm(3) s(-1) for aqueous solutions and 440.9 ± 0.5 mm(3) s(-1) for blood. By combining 3DP and directional freezing, we can control the micro- and macro-architecture of Ch-Al to drastically improve cell influx into and distribution within the scaffold

  15. Macro- and micro-designed chitosan-alginate scaffold architecture by three-dimensional printing and directional freezing.

    PubMed

    Reed, Stephanie; Lau, Grace; Delattre, Benjamin; Lopez, David Don; Tomsia, Antoni P; Wu, Benjamin M

    2016-03-01

    While many tissue-engineered constructs aim to treat cartilage defects, most involve chondrocyte or stem cell seeding on scaffolds. The clinical application of cell-based techniques is limited due to the cost of maintaining cellular constructs on the shelf, potential immune response to allogeneic cell lines, and autologous chondrocyte sources requiring biopsy from already diseased or injured, scarce tissue. An acellular scaffold that can induce endogenous influx and homogeneous distribution of native stem cells from bone marrow holds great promise for cartilage regeneration. This study aims to develop such an acellular scaffold using designed, channeled architecture that simultaneously models the native zones of articular cartilage and subchondral bone. Highly porous, hydrophilic chitosan-alginate (Ch-Al) scaffolds were fabricated in three-dimensionally printed (3DP) molds designed to create millimeter scale macro-channels. Different polymer preform casting techniques were employed to produce scaffolds from both negative and positive 3DP molds. Macro-channeled scaffolds improved cell suspension distribution and uptake overly randomly porous scaffolds, with a wicking volumetric flow rate of 445.6 ± 30.3 mm(3) s(-1) for aqueous solutions and 177 ± 16 mm(3) s(-1) for blood. Additionally, directional freezing was applied to Ch-Al scaffolds, resulting in lamellar pores measuring 300 μm and 50 μm on the long and short axes, thus creating micrometer scale micro-channels. After directionally freezing Ch-Al solution cast in 3DP molds, the combined macro- and micro-channeled scaffold architecture enhanced cell suspension uptake beyond either macro- or micro-channels alone, reaching a volumetric flow rate of 1782.1 ± 48 mm(3) s(-1) for aqueous solutions and 440.9 ± 0.5 mm(3) s(-1) for blood. By combining 3DP and directional freezing, we can control the micro- and macro-architecture of Ch-Al to drastically improve cell influx into and distribution within the scaffold

  16. Study of Carbon Nano-Tubes Effects on the Chondrogenesis of Human Adipose Derived Stem Cells in Alginate Scaffold

    PubMed Central

    Valiani, Ali; Hashemibeni, Batool; Esfandiary, Ebrahim; Ansar, Malek Masoud; Kazemi, Mohammad; Esmaeili, Nafiseh

    2014-01-01

    Background: Osteoarthritis is one of the most common diseases in middle-aged populations in the World and could become the fourth principal cause of disability by the year 2020. One of the critical properties for cartilage tissue engineering (TE) is the ability of scaffolds to closely mimic the extracellular matrix and bond to the host tissue. Therefore, TE has been presented as a technique to introduce the best combination of cells and biomaterial scaffold and to stimulate growth factors to produce a cartilage tissue resembling natural articular cartilage. The aim of study is to improve differentiation of adipose derived stem cells (ADSCs) into chondrocytes in order to provide a safe and modern treatment for patients suffering from cartilage damages. Methods: After functionalization, dispersions and sterilizing carbon nano-tubes (CNTs), a new type of nanocomposite gel was prepared from water-soluble CNTs and alginate. ADSCs seeded in 1.5% alginate scaffold and cultured in chondrogenic media with and without transforming growth factor-β1 (TGF-β1) for 7 and 14 days. The genes expression of sex determining region Y-box 9 (SOX9), types II and X collagens was assessed by real-time polymerase chain reaction and the amount of aggrecan (AGC) and type I collagen was measured by ELISA. Results: Our findings showed that the expression of essential cartilage markers, SOX9, type II collagen and AGC, in differentiated ADSCs at the concentration of 1 μg/ml CNTs in the presence of TGF-β1 were significantly increased in comparison with the control group (P < 0.001). Meanwhile, type X collagen expression and also type I collagen production were significantly decreased (P < 0.001). Conclusions: The results showed that utilized three-dimensional scaffold had a brilliant effect in promoting gene expression of chondrogenesis. PMID:25104993

  17. Proliferation and enrichment of CD133(+) glioblastoma cancer stem cells on 3D chitosan-alginate scaffolds.

    PubMed

    Kievit, Forrest M; Florczyk, Stephen J; Leung, Matthew C; Wang, Kui; Wu, Jennifer D; Silber, John R; Ellenbogen, Richard G; Lee, Jerry S H; Zhang, Miqin

    2014-11-01

    Emerging evidence implicates cancer stem cells (CSCs) as primary determinants of the clinical behavior of human cancers, representing an ideal target for next-generation anti-cancer therapies. However CSCs are difficult to propagate in vitro, severely limiting the study of CSC biology and drug development. Here we report that growing cells from glioblastoma (GBM) cell lines on three dimensional (3D) porous chitosan-alginate (CA) scaffolds dramatically promotes the proliferation and enrichment of cells possessing the hallmarks of CSCs. CA scaffold-grown cells were found more tumorigenic in nude mouse xenografts than cells grown from monolayers. Growing in CA scaffolds rapidly promoted expression of genes involved in the epithelial-to-mesenchymal transition that has been implicated in the genesis of CSCs. Our results indicate that CA scaffolds have utility as a simple and inexpensive means to cultivate CSCs in vitro in support of studies to understand CSC biology and develop more effective anti-cancer therapies.

  18. Enhanced cellular activities of polycaprolactone/alginate-based cell-laden hierarchical scaffolds for hard tissue engineering applications.

    PubMed

    Lee, HyeongJin; Kim, GeunHyung

    2014-09-15

    Biomedical scaffolds have been widely investigated because they are essential for support and promotion of cell adhesion, proliferation and differentiation in three-dimensional (3D) structures. An ideal scaffold should be highly porous to enable efficient nutrient and oxygen transfer and have a 3D structure that provides optimal micro-environmental conditions for the seeded cells to obtain homogeneous growth after a long culture period. In this study, new hierarchical osteoblast-like cell (MG-63)-laden scaffolds consisting of micro-sized struts/inter-layered micro-nanofibres and cell-laden hydrogel struts with mechanically stable and biologically superior properties were introduced. Poly(ethylene oxide) (PEO) was used as a sacrificial component to generate pores within the cell-laden hydrogel struts to attain a homogeneous cell distribution and rapid cell growth in the scaffold interior. The alginate-based cell-laden struts with PEO induced fast/homogeneous cell release, in contrast to nonporous cell-laden struts. Various weight fractions (0.5, 1, 2, 3 and 3.5 wt%) of PEO were used, of which 2 wt% PEO in the cell-laden strut resulted in the most appropriate cell release and enhanced biological activities (cell proliferation and calcium deposition), compared to nonporous cell-laden struts.

  19. Mechanical properties, biological behaviour and drug release capability of nano TiO2-HAp-Alginate composite scaffolds for potential application as bone implant material.

    PubMed

    Naik, Kshipra; Chandran, V Girish; Rajashekaran, Raghavan; Waigaonkar, Sachin; Kowshik, Meenal

    2016-09-01

    Nanocomposite scaffolds of TiO2 and hydroxyapatite nanoparticles with alginate as the binding agent were fabricated using the freeze drying technique. TiO2, hydroxyapatite and alginate were used in the ratio of 1:1:4. The scaffolds were characterized using X-ray diffraction, fourier transform infrared spectroscopy, and scanning electron microscopy. The biocompatibility of the scaffolds was evaluated using cell adhesion and MTT assay on osteosarcoma (MG-63) cells. Scanning electron microscopy analysis revealed that cells adhered to the surface of the scaffolds with good spreading. The mechanical properties of the scaffolds were investigated using dynamic mechanical analysis. The swelling ability, porosity, in vitro degradation, and biomineralization of the scaffolds were also evaluated. The results indicated controlled swelling, limited degradation, and enhanced biomineralization. Further, drug delivery studies of the scaffolds using the chemotherapeutic drug methotrexate exhibited an ideal drug release profile. These scaffolds are proposed as potential candidates for bone tissue engineering and drug delivery applications. PMID:27485954

  20. Mechanical properties, biological behaviour and drug release capability of nano TiO2-HAp-Alginate composite scaffolds for potential application as bone implant material.

    PubMed

    Naik, Kshipra; Chandran, V Girish; Rajashekaran, Raghavan; Waigaonkar, Sachin; Kowshik, Meenal

    2016-09-01

    Nanocomposite scaffolds of TiO2 and hydroxyapatite nanoparticles with alginate as the binding agent were fabricated using the freeze drying technique. TiO2, hydroxyapatite and alginate were used in the ratio of 1:1:4. The scaffolds were characterized using X-ray diffraction, fourier transform infrared spectroscopy, and scanning electron microscopy. The biocompatibility of the scaffolds was evaluated using cell adhesion and MTT assay on osteosarcoma (MG-63) cells. Scanning electron microscopy analysis revealed that cells adhered to the surface of the scaffolds with good spreading. The mechanical properties of the scaffolds were investigated using dynamic mechanical analysis. The swelling ability, porosity, in vitro degradation, and biomineralization of the scaffolds were also evaluated. The results indicated controlled swelling, limited degradation, and enhanced biomineralization. Further, drug delivery studies of the scaffolds using the chemotherapeutic drug methotrexate exhibited an ideal drug release profile. These scaffolds are proposed as potential candidates for bone tissue engineering and drug delivery applications.

  1. Cell-Laden Poly(ɛ-caprolactone)/Alginate Hybrid Scaffolds Fabricated by an Aerosol Cross-Linking Process for Obtaining Homogeneous Cell Distribution: Fabrication, Seeding Efficiency, and Cell Proliferation and Distribution

    PubMed Central

    Lee, HyeongJin; Ahn, SeungHyun; Bonassar, Lawrence J.; Chun, Wook

    2013-01-01

    Generally, solid-freeform fabricated scaffolds show a controllable pore structure (pore size, porosity, pore connectivity, and permeability) and mechanical properties by using computer-aided techniques. Although the scaffolds can provide repeated and appropriate pore structures for tissue regeneration, they have a low biological activity, such as low cell-seeding efficiency and nonuniform cell density in the scaffold interior after a long culture period, due to a large pore size and completely open pores. Here we fabricated three different poly(ɛ-caprolactone) (PCL)/alginate scaffolds: (1) a rapid prototyped porous PCL scaffold coated with an alginate, (2) the same PCL scaffold coated with a mixture of alginate and cells, and (3) a multidispensed hybrid PCL/alginate scaffold embedded with cell-laden alginate struts. The three scaffolds had similar micropore structures (pore size=430–580 μm, porosity=62%–68%, square pore shape). Preosteoblast cells (MC3T3-E1) were used at the same cell density in each scaffold. By measuring cell-seeding efficiency, cell viability, and cell distribution after various periods of culturing, we sought to determine which scaffold was more appropriate for homogeneously regenerated tissues. PMID:23469894

  2. Cell-laden poly(ɛ-caprolactone)/alginate hybrid scaffolds fabricated by an aerosol cross-linking process for obtaining homogeneous cell distribution: fabrication, seeding efficiency, and cell proliferation and distribution.

    PubMed

    Lee, HyeongJin; Ahn, SeungHyun; Bonassar, Lawrence J; Chun, Wook; Kim, GeunHyung

    2013-10-01

    Generally, solid-freeform fabricated scaffolds show a controllable pore structure (pore size, porosity, pore connectivity, and permeability) and mechanical properties by using computer-aided techniques. Although the scaffolds can provide repeated and appropriate pore structures for tissue regeneration, they have a low biological activity, such as low cell-seeding efficiency and nonuniform cell density in the scaffold interior after a long culture period, due to a large pore size and completely open pores. Here we fabricated three different poly(ɛ-caprolactone) (PCL)/alginate scaffolds: (1) a rapid prototyped porous PCL scaffold coated with an alginate, (2) the same PCL scaffold coated with a mixture of alginate and cells, and (3) a multidispensed hybrid PCL/alginate scaffold embedded with cell-laden alginate struts. The three scaffolds had similar micropore structures (pore size = 430-580 μm, porosity = 62%-68%, square pore shape). Preosteoblast cells (MC3T3-E1) were used at the same cell density in each scaffold. By measuring cell-seeding efficiency, cell viability, and cell distribution after various periods of culturing, we sought to determine which scaffold was more appropriate for homogeneously regenerated tissues.

  3. Shape-memory porous alginate scaffolds for regeneration of the annulus fibrosus: effect of TGF-β3 supplementation and oxygen culture conditions.

    PubMed

    Guillaume, Olivier; Daly, Andrew; Lennon, Kerri; Gansau, Jennifer; Buckley, Shane F; Buckley, Conor T

    2014-05-01

    Disc herniation as a result of degenerative or traumatic injury is believed to be the primary instigator of low back pain. At present there is a lack of viable treatment options to repair damaged annulus fibrosus (AF) tissue. Developing alternative strategies to fill and repair ruptured AF tissue is a key challenge. In this work we developed a porous alginate scaffold with shape-memory properties which can be delivered using minimally invasive approaches and recover its original geometry once hydrated. Covalently cross-linked alginate hydrogels were created using carbodiimide chemistry, followed by a freeze-drying step to impart porosity and create porous scaffolds. Results showed that porous alginate scaffolds exhibited shape-memory recovery and mechanical behaviour that could be modulated depending on the cross-linker concentrations. The scaffold can be repeatedly compressed and expanded, which provides the potential to deliver the biomaterial directly to the damaged area of the AF tissue. In vitro experiments demonstrated that scaffolds were cytocompatible and supported cell seeding, penetration and proliferation under intervertebral-disc-like microenvironmental conditions (low glucose media and low oxygen concentration). Extracellular matrix (ECM) was secreted by AF cells with TGF-β3 stimulation and after 21days had filled the porous scaffold network. This biological matrix was rich in sulfated glycosaminoglycan and collagen type I, which are the main compounds of native AF tissue. Successful ECM deposition was also confirmed by the increase in the peak stress of the scaffold. However, the immaturity of the matrix network after only 21days of in vitro culture was not sufficient to attain native AF tissue mechanical properties. The ability to deliver porous scaffolds using minimal invasive approaches that can potentially promote the regeneration of AF defects provides an exciting new avenue for disc repair.

  4. Design and Fabrication of Anatomical Bioreactor Systems Containing Alginate Scaffolds for Cartilage Tissue Engineering

    PubMed Central

    Gharravi, Anneh Mohammad; Orazizadeh, Mahmoud; Ansari-Asl, Karim; Banoni, Salem; Izadi, Sina; Hashemitabar, Mahmoud

    2012-01-01

    The aim of the present study was to develop a tissue-engineering approach through alginate gel molding to mimic cartilage tissue in a three-dimensional culture system. The perfusion biomimetic bioreactor was designed to mimic natural joint. The shear stresses exerting on the bioreactor chamber were calculated by Computational Fluid Dynamic (CFD). Several alginate/bovine chondrocyte constructs were prepared, and were cultured in the bioreactor. Histochemical and immunohistochemical staining methods for the presence of glycosaminoglycan(GAG), overall matrix production and type II collagen protein were performed, respectively. The dynamic mechanical device applied a linear mechanical displacement of 2 mm to 10 mm. The CFD modeling indicated peak velocity and maximum wall shear stress were 1.706×10−3 m/s and 0.02407 dyne/cm 2, respectively. Histochemical and immunohistochemical analysis revealed evidence of cartilage-like tissue with lacunas similar to those of natural cartilage and the production of sulfated GAG of matrix by the chondrons, metachromatic territorial matrix-surrounded cells and accumulation of type II collagen around the cells. The present study indicated that when chondrocytes were seeded in alginate hydrogel and cultured in biomimetic cell culture system, cells survived well and secreted newly synthesized matrix led to improvement of chondrogenesis. PMID:23408660

  5. Synthesis and biocompatibility of porous nano-hydroxyapatite/collagen/alginate composite.

    PubMed

    Zhang, S M; Cui, F Z; Liao, S S; Zhu, Y; Han, L

    2003-07-01

    Porous nano-hydroxyapatite/collagen/alginate (nHAC/Alginate) composite containing nHAC and Ca-crosslinked alginate is synthesized biomimetically. This composite shows a significant improvement in mechanical properties over nHAC material. Mechanical test results show that the compressive modulus and yield strength of this composite are in direct proportion to the percentage of Ca-crosslinked alginate in the composite. Primary biocompatibility experiments in vitro including fibroblasts and osteoblasts co-culture with nHAC/alginate composite indicated the high biocompatibility of this composite. Therefore the composite can be a promising candidate of scaffold material for bone tissue engineering.

  6. Bone regeneration potential of stem cells derived from periodontal ligament or gingival tissue sources encapsulated in RGD-modified alginate scaffold.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H; Shi, Songtao

    2014-02-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications. PMID:24070211

  7. Bone Regeneration Potential of Stem Cells Derived from Periodontal Ligament or Gingival Tissue Sources Encapsulated in RGD-Modified Alginate Scaffold

    PubMed Central

    Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H.; Shi, Songtao

    2014-01-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications. PMID:24070211

  8. Cells (MC3T3-E1)-laden alginate scaffolds fabricated by a modified solid-freeform fabrication process supplemented with an aerosol spraying.

    PubMed

    Ahn, SeungHyun; Lee, HyeongJin; Bonassar, Lawrence J; Kim, GeunHyung

    2012-09-10

    In this study, we propose a new cell encapsulation method consisting of a dispensing method and an aerosol-spraying method. The aerosol spray using a cross-linking agent, calcium chloride (CaCl(2)), was used to control the surface gelation of dispensed alginate struts during dispensing. To show the feasibility of the method, we used preosteoblast (MC3T3-E1) cells. By changing the relationship between the various dispensing/aerosol-spraying conditions and cell viability, we could determine the optimal cell-dispensing process: a nozzle size (240 μm) and an aerosol spray flow rate (0.93 ± 0.12 mL min(-1)), 10 mm s(-1) nozzle moving speed, a 10 wt % concentration of CaCl(2) in the aerosol solution, and 2 wt % concentration of CaCl(2) in the second cross-linking process. Based on these optimized process conditions, we successfully fabricated a three-dimensional, pore-structured, cell-laden alginate scaffold of 20 × 20 × 4.6 mm(3) and 84% cell viability. During long cell culture periods (16, 25, 33, and 45 days), the preosteoblasts in the alginate scaffold survived and proliferated well.

  9. Thermogelling Bioadhesive Scaffolds for Intervertebral Disc Tissue Engineering: Preliminary In Vitro Comparison of Aldehyde-Based Versus Alginate Microparticle-Mediated Adhesion

    PubMed Central

    Wiltsey, C.; Christiani, T.; Williams, J.; Scaramazza, J.; Van Sciver, C.; Toomer, K.; Sheehan, J.; Branda, A.; Nitzl, A.; England, E.; Kadlowec, J.; Iftode, C.; Vernengo, J.

    2015-01-01

    Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or “end-capping”, the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase two-fold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration. PMID:25641647

  10. Thermogelling bioadhesive scaffolds for intervertebral disk tissue engineering: preliminary in vitro comparison of aldehyde-based versus alginate microparticle-mediated adhesion.

    PubMed

    Wiltsey, C; Christiani, T; Williams, J; Scaramazza, J; Van Sciver, C; Toomer, K; Sheehan, J; Branda, A; Nitzl, A; England, E; Kadlowec, J; Iftode, C; Vernengo, J

    2015-04-01

    Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or "end-capping", the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase twofold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration.

  11. Thermogelling bioadhesive scaffolds for intervertebral disk tissue engineering: preliminary in vitro comparison of aldehyde-based versus alginate microparticle-mediated adhesion.

    PubMed

    Wiltsey, C; Christiani, T; Williams, J; Scaramazza, J; Van Sciver, C; Toomer, K; Sheehan, J; Branda, A; Nitzl, A; England, E; Kadlowec, J; Iftode, C; Vernengo, J

    2015-04-01

    Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or "end-capping", the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase twofold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration. PMID:25641647

  12. Poly-L-lactide/sodium alginate/chitosan microsphere hybrid scaffolds made with braiding manufacture and adhesion technique: Solution to the incongruence between porosity and compressive strength.

    PubMed

    Lin, Jia-Horng; Chen, Chih-Kuang; Wen, Shih-Peng; Lou, Ching-Wen

    2015-01-01

    Bone scaffolds require a three-dimensional structure, high porosity, interconnected pores, adequate mechanical strengths, and non-toxicity. A high porosity is incongruent with mechanical strengths. Therefore, this study combines a braiding method and microsphere solution to create bone scaffolds with a high porosity and sufficient mechanical strengths. First, poly-L-lactide (PLLA) plied yarns are braided into 5-, 10-, 15-, 20-, and 25-layer hollow braids, and then thermally treated at 165 °C for various durations. Next, sodium alginate (SA) microspheres, cross-linked with CaCl2 solution with various concentrations, are combined with PLLA porous braided bone scaffolds to form PLLA/SA/CS microsphere hybrid scaffolds, which are then observed for surface observation, and tested for porosity, water contact angle, compressive strength, MTT assay, bioactivity, alkaline phosphatase (ALP) assay, cell attachment, and statistical analyses. The test results show that the layer amount of the bone scaffold is proportional to the compressive strength. With the same number of layers, the compressive strength is inversely proportional to the concentration of the CaCl2 solution. The results of surface observation, porosity, and water contact angle tests show that PLLA/SA/CS microsphere hybrid scaffolds possess a high porosity and good hydrophilicity; as a result, the braiding manufacture and the bonding technique effectively solve the confliction between porosity and mechanical strength. The concentration of CaCl2 does not pertain to cell activity and ALP results, exemplified by good cell attachment on bone scaffolds for each specification. PMID:25953547

  13. Hybrid Polycaprolactone/Alginate Scaffolds Functionalized with VEGF to Promote de Novo Vessel Formation for the Transplantation of Islets of Langerhans.

    PubMed

    Marchioli, Giulia; Luca, Andrea Di; de Koning, Eelco; Engelse, Marten; Van Blitterswijk, Clemens A; Karperien, Marcel; Van Apeldoorn, Aart A; Moroni, Lorenzo

    2016-07-01

    Although regarded as a promising treatment for type 1 diabetes, clinical islet transplantation in the portal vein is still hindered by a low transplantation outcome. Alternative transplantation sites have been proposed, but the survival of extra-hepatically transplanted islets of Langerhans critically depends on quick revascularization after engraftment. This study aims at developing a new 3D scaffold platform that can actively boost vascularization and may find an application for extra-hepatic islet transplantation. The construct consists of a 3D ring-shaped polycaprolactone (PCL) scaffold with heparinized surface to electrostatically bind vascular endothelial growth factor (VEGF), surrounding a hydrogel core for islets encapsulation. Heparin immobilization improves the amount of VEGF retained by the construct, up to 3.6 fold, compared to untreated PCL scaffolds. In a chicken chorioallanthoic membrane model, VEGF immobilized on the construct enhances angiogenesis in close proximity and on the surface of the scaffolds. After 7 days, islets encapsulated in the alginate core show functional response to glucose stimuli comparable to free-floating islets. Thus, the developed platform has the potential to support rapid vascularization and islet endocrine function. PMID:27113576

  14. CellMAC: a novel technology for encapsulation of mammalian cells in cellulose sulfate/pDADMAC capsules assembled on a transient alginate/Ca2+ scaffold.

    PubMed

    Weber, Wilfried; Rinderknecht, Matthias; Daoud-El Baba, Marie; de Glutz, François-Nicolas; Aubel, Dominique; Fussenegger, Martin

    2004-11-01

    Microencapsulation of desired mammalian cell phenotypes in biocompatible polymer matrices represents a powerful technology for cell-based therapies and biopharmaceutical manufacturing of protein therapeutics. We have pioneered a novel jet break-up-compatible process for encapsulation of mammalian cells in cellulose sulfate (CS)/poly-diallyl-dimethyl-ammoniumchloride (pDADMAC) (CellMAC) capsules. CS and pDADMAC polymerize on a transient ad hoc co-assembled Ca2+/alginate scaffold and form homogenous capsules following dissolution of the alginate core by Ca2+ chelating agents. CellMAC capsules exhibited excellent mechanical properties and showed a molecular weight cut-off between 43 and 77kDa. Chinese hamster ovary cells engineered for constitutive production of the glycohormone erythropoietin reached high viable cell densities when grown inside CellMAC capsules, while specific erythropoietin (EPO) productivities matched those of conventional non-encapsulated control cultures. CellMAC-encapsulated EPO-production cell lines induced increased EPO serum levels when implanted intraperitoneally into mice and provided robust glycoprotein production during standard stirred-tank bioreactor operation. We expect the CellMAC technology to foster advances in therapeutic encapsulation of engineered cell lines as well as manufacturing of protein pharmaceuticals.

  15. Integration of a Novel Injectable Nano Calcium Sulfate/Alginate Scaffold and BMP2 Gene-Modified Mesenchymal Stem Cells for Bone Regeneration

    PubMed Central

    He, Xiaoning; Dziak, Rosemary; Mao, Keya; Genco, Robert; Swithart, Mark; Li, Chunyi

    2013-01-01

    The repair of craniofacial bone defects is surgically challenging due to the complex anatomical structure of the craniofacial skeleton. Current strategies for bone tissue engineering using a preformed scaffold have not resulted in the expected clinical regeneration due to difficulty in seeding cells into the deep internal space of scaffold, and the inability to inject them in minimally invasive surgeries. In this study, we used the osteoconductive and mechanical properties of nano-scale calcium sulfate (nCS) and the biocompatibility of alginate to develop the injectable nCS/alginate (nCS/A) paste, and characterized the effect of this nCS/A paste loaded with bone morphogenetic protein 2 (BMP2) gene-modified rat mesenchymal stem cells (MSCs) on bone and blood vessel growth. Our results showed that the nCS/A paste was injectable under small injection forces. The mechanical properties of the nCS/A paste were increased with an increased proportion of alginate. MSCs maintained their viability after the injection, and MSCs and BMP2 gene-modified MSCs in the injectable pastes remained viable, osteodifferentiated, and yielded high alkaline phosphatase activity. By testing the ability of this injectable paste and BMP2-gene-modified MSCs for the repair of critical-sized calvarial bone defects in a rat model, we found that BMP2-gene-modified MSCs in nCS/A (nCS/A+M/B2) showed robust osteogenic activity, which resulted in consistent bone bridging of the bone defects. The vessel density in nCS/A+M/B2 was significantly higher than that in the groups of blank control, nCS/A alone, and nCS/A mixed with MSCs (nCS/A+M). These results indicate that BMP2 promotes MSCs-mediated bone formation and vascularization in nCS/A paste. Overall, the results demonstrated that the combination of injectable nCS/A paste and BMP2-gene-modified MSCs is a new and effective strategy for the repair of bone defects. PMID:22994418

  16. Factors influencing alginate gel biocompatibility.

    PubMed

    Tam, Susan K; Dusseault, Julie; Bilodeau, Stéphanie; Langlois, Geneviève; Hallé, Jean-Pierre; Yahia, L'Hocine

    2011-07-01

    Alginate remains the most popular polymer used for cell encapsulation, yet its biocompatibility is inconsistent. Two commercially available alginates were compared, one with 71% guluronate (HiG), and the other with 44% (IntG). Both alginates were purified, and their purities were verified. After 2 days in the peritoneal cavity of C57BL/6J mice, barium (Ba)-gel and calcium (Ca)-gel beads of IntG alginate were clean, while host cells were adhered to beads of HiG alginate. IntG gel beads, however, showed fragmentation in vivo while HiG gel beads stayed firm. The physicochemical properties of the sodium alginates and their gels were thoroughly characterized. The intrinsic viscosity of IntG alginate was 2.5-fold higher than that of HiG alginate, suggesting a greater molecular mass. X-ray photoelectron spectroscopy indicated that both alginates were similar in elemental composition, including low levels of counterions in all gels. The wettabilities of the alginates and gels were also identical, as measured by contact angles of water on dry films. Ba-gel beads of HiG alginate resisted swelling and degradation when immersed in water, much more than the other gel beads. These results suggest that the main factors contributing to the biocompatibility of gels of purified alginate are the mannuronate/guluronate content and/or intrinsic viscosity.

  17. Boron nitride nanotubes included thermally cross-linked gelatin-glucose scaffolds show improved properties.

    PubMed

    Şen, Özlem; Culha, Mustafa

    2016-02-01

    Boron nitride nanotubes (BNNTs) are increasingly investigated for their medical and biomedical applications due to their unique properties such as resistance to oxidation, thermal and electrical insulation, and biocompatibility. BNNTs can be used to enhance mechanical strength of biomedical structures such as scaffolds in tissue engineering applications. In this study, we report the use of BNNTs and hydroxylated BNNTs (BNNT-OH) to improve the properties of gelatin-glucose scaffolds prepared with electrospinning technique. Human dermal fibroblast (HDF) cells are used for the toxicity assessment and cell seeding studies. It is found that the addition of BNNTs into the scaffold does not influence cell viability, decreases the scaffold degradation rate, and improves cell attachment and proliferation compared to only-gelatin scaffold.

  18. Novel alginate-based nanocarriers as a strategy to include high concentrations of hydrophobic compounds in hydrogels for topical application

    NASA Astrophysics Data System (ADS)

    Nguyen, H. T. P.; Munnier, E.; Souce, M.; Perse, X.; David, S.; Bonnier, F.; Vial, F.; Yvergnaux, F.; Perrier, T.; Cohen-Jonathan, S.; Chourpa, I.

    2015-06-01

    The cutaneous penetration of hydrophobic active molecules is of foremost concern in the dermatology and cosmetic formulation fields. The poor solubility in water of those molecules limits their use in hydrophilic forms such as gels, which are favored by patients with chronic skin disease. The aim of this work is to design a novel nanocarrier of hydrophobic active molecules and to determine its potential as an ingredient of a topical form. The nanocarrier consists of an oily core surrounded by a protective shell of alginate, a natural polysaccharide isolated from brown algae. These calcium alginate-based nanocarriers (CaANCs) were prepared at room temperature and without the use of organic solvent by an accelerated nanoemulsification-polymer crosslinking method. The size (hydrodynamic diameter ˜200 nm) and surface charge (zeta potential ˜ - 30 mV) of the CaANCs are both compatible with their application on skin. CaANCs loaded with a fluorescent label were stable in model hydrophilic galenic forms under different storage conditions. Curcumin was encapsulated in CaANCs with an efficiency of ˜95%, fully retaining its antioxidant activity. The application of the curcumin-loaded CaANCs on excised human skin led to a significant accumulation of the active molecules in the upper layers of the skin, asserting the potential of these nanocarriers in active pharmaceutical and cosmetic ingredients topical delivery.

  19. 3D Cell Culture in Alginate Hydrogels

    PubMed Central

    Andersen, Therese; Auk-Emblem, Pia; Dornish, Michael

    2015-01-01

    This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell–matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue. PMID:27600217

  20. 3D Cell Culture in Alginate Hydrogels

    PubMed Central

    Andersen, Therese; Auk-Emblem, Pia; Dornish, Michael

    2015-01-01

    This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell–matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue.

  1. 3D Cell Culture in Alginate Hydrogels.

    PubMed

    Andersen, Therese; Auk-Emblem, Pia; Dornish, Michael

    2015-03-24

    This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell-matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue.

  2. Understanding Alginate Gel Development for Bioclogging and Biogeophysical Experiments

    NASA Astrophysics Data System (ADS)

    Brown, I.; Atekwana, E. A.; Abdel Aal, G. Z.; Atekwana, E. A.; Sarkisova, S.; Patrauchan, M.

    2012-12-01

    Bioremediation strategies to mitigate the transport of heavy metals and radionuclides in subsurface sediments have largely targeted to increase the mobility and/or solubility of these compounds by the stimulation of biogeochemical activity of the metal- and sulfate-reducing bacteria. The latter secrete and/or release out diverse biochemical molecule including, first of all, organic acids and biopolymers such as alginic acid, proteins and DNA. Alginate gel is one of the major components determining the structure of biofilm which causes clogging in porous media. Biopolymers composing biofilm having, at least, two main functions: to be a scaffold for a microbial biofilm, and to regulate the exchange of metabolites and ions between an environment and bacterial cells. Additionally, the accumulation of biopolymers and a matured biofilm within porous media was shown to contribute to a detectable biogeophysical signal, spectral induced polarization (SIP), in particular. Our objective is to understand the role of different biofilm components on the SIP response as the latter has been proposed as a non-invasive tool to monitor biofilm development and rate of clogging in the subsurface. Understanding the process of alginate gel development may aid in the understanding of the fate and transport of mineralized heavy metals and radionuclides in contaminated soils. Here we describe the reciprocal relationship between environmental chemistry and alginate gel development. Commercial (Sigma) alginic acid (AA) was used as a substratum for the preparation of a model gel. AA was solubilized by adjusting solutions with pH up to 4 with 0.1 NaOH. Both Ca(OH)2 or CaCl2 were used to initiate the gelation of alginate. pH, fluid conductivity, soluble Ca2+ concentration, and a yield of gelated alginate were monitored in both liquid and porous media after the interaction of calcium compounds with alginate. This study confirms the critical role of Ca2+ for alginate gelation, biofilm development

  3. Jellyfish collagen and alginate: Combined marine materials for superior chondrogenesis of hMSC.

    PubMed

    Pustlauk, W; Paul, B; Gelinsky, M; Bernhardt, A

    2016-07-01

    Marine, hybrid constructs of porous scaffolds from fibrillized jellyfish collagen and alginate hydrogel are mimicking both of the main tissue components of cartilage, thus being a promising approach for chondrogenic differentiation of human mesenchymal stem cells (hMSC). Investigating their potential for articular cartilage repair, the present study examined scaffolds being either infiltrated with an alginate-cell-suspension (ACS) or seeded with hMSC and embedded in alginate after cell adhesion (EAS). Hybrid constructs with 2×10(5) and 4.5×10(5)hMSC/scaffold were compared to hMSC encapsulated in pure alginate discs, both chondrogenically stimulated for 21days. Typical round, chondrocyte-like morphology was observed in pure alginate gels and ACS scaffolds, while cells in EAS were elongated and tightly attached to the collagen pores. Col 2 gene expression was comparable in all scaffold types examined. However, the Col 2/Col 1 ratio was higher for pure alginate discs and ACS scaffolds compared to EAS. In contrast, cells in EAS scaffolds displayed higher gene expression of Sox 9, Col 11 and ACAN compared to ACS and pure alginate. Secretion of sulfated glycosaminoglycans (sGAG) was comparable for ACS and EAS scaffolds. In conclusion hybrid constructs of jellyfish collagen and alginate support hMSC chondrogenic differentiation and provide more stable and constructs compared to pure hydrogels. PMID:27127044

  4. Alginate: properties and biomedical applications

    PubMed Central

    Lee, Kuen Yong; Mooney, David J.

    2011-01-01

    Alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications to date, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers. PMID:22125349

  5. Development of a morphogenetically active scaffold for three-dimensional growth of bone cells: biosilica-alginate hydrogel for SaOS-2 cell cultivation.

    PubMed

    Müller, Werner E G; Schröder, Heinz C; Feng, Qingling; Schlossmacher, Ute; Link, Thorben; Wang, Xiaohong

    2015-11-01

    Polymeric silica is formed from ortho-silicate during a sol-gel formation process, while biosilica is the product of an enzymatically driven bio-polycondensation reaction. Both polymers have recently been described as a template that induces an increased expression of the genes encoding bone morphogenetic protein 2 (BMP-2) and osteoprotegerin in osteoblast-related SaOS-2 cells; simultaneously or subsequently the cells respond with enhanced hydroxyapatite formation. In order to assess whether the biocompatible polymeric silica/biosilica can serve as a morphogenetically active matrix suitable for three-dimensional (3D) cell growth, or even for 3D cell bioprinting, SaOS-2 cells were embedded into a Na-alginate-based hydrogel. Four different gelatinous hydrogel matrices were used for suspending SaOS-2 cells: (a) the hydrogel alone; (b) the hydrogel with 400 μM ortho-silicate; (c) the hydrogel supplemented with 400 μM ortho-silicate and recombinant silicatein to allow biosilica synthesis to occur; and (d) the hydrogel with ortho-silicate and BSA. The SaOS-2 cells showed an increased growth if silica/biosilica components were present in the hydrogel. Likewise intensified was the formation of hydroxyapatite nodules in the silica-containing hydrogels. After an incubation period of 2 weeks, cells present in silica-containing hydrogels showed a significantly higher expression of the genes encoding the cytokine BMP-2, the major fibrillar structural protein collagen 1 and likewise of carbonic anhydrase. It is concluded that silica, and to a larger extent biosilica, retains its morphogenetic/osteogenic potential after addition to Na-alginate-based hydrogels. This property might qualify silica hydrogels to be also used as a matrix for 3D cell printing.

  6. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    NASA Astrophysics Data System (ADS)

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-08-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering.

  7. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    PubMed Central

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-01-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering. PMID:27578567

  8. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies.

    PubMed

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M

    2016-01-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca(2+) ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering. PMID:27578567

  9. Preparation and characterization of hydroxyapatite/sodium alginate biocomposites for bone implant application

    NASA Astrophysics Data System (ADS)

    Kanasan, Nanthini; Adzila, Sharifah; Suid, Mohd Syafiq; Gurubaran, P.

    2016-07-01

    In biomedical fields, synthetic scaffolds are being improved by using the ceramics, polymers and composites materials to avoid the limitations of allograft. Ceramic-polymer composites are appearing to be the most successful bone graft substitute in human body. The natural bones itself are well-known as composite of collagen and hydroxyapatite. In this research, precipitation method was used to synthesis hydroxyapatite (HA)/sodium alginate (SA) in various parameters. This paper describes the hydroxyapatite/sodium alginate biocomposite which suitable for use in bone defects or regeneration of bone through the characterizations which include FTIR, FESEM, EDS and DTA. In FTIR, the characteristi peaks of PO4-3 and OH- groups which corresponding to hydroxyapatite are existed in the mixing powders. The needle-size particle of hydroxyapatite/ alginate (HA/SA) are observed in FESEM in the range of 15.8nm-38.2nm.EDS confirmed the existence of HA/SA composition in the mixing powders. There is an endothermic peak which corresponds to the dehydration and the loss of physically adsorbed water molecules of the hydroxyapatite (HA)/sodium alginate (SA) powder which are described in DTA.

  10. Chitosan-Alginate Biocomposite Containing Fucoidan for Bone Tissue Engineering

    PubMed Central

    Venkatesan, Jayachandran; Bhatnagar, Ira; Kim, Se-Kwon

    2014-01-01

    Over the last few years, significant research has been conducted in the construction of artificial bone scaffolds. In the present study, different types of polymer scaffolds, such as chitosan-alginate (Chi-Alg) and chitosan-alginate with fucoidan (Chi-Alg-fucoidan), were developed by a freeze-drying method, and each was characterized as a bone graft substitute. The porosity, water uptake and retention ability of the prepared scaffolds showed similar efficacy. The pore size of the Chi-Alg and Chi-Alg-fucoidan scaffolds were measured from scanning electron microscopy and found to be 62–490 and 56–437 µm, respectively. In vitro studies using the MG-63 cell line revealed profound cytocompatibility, increased cell proliferation and enhanced alkaline phosphatase secretion in the Chi-Alg-fucoidan scaffold compared to the Chi-Alg scaffold. Further, protein adsorption and mineralization were about two times greater in the Chi-Alg-fucoidan scaffold than the Chi-Alg scaffold. Hence, we suggest that Chi-Alg-fucoidan will be a promising biomaterial for bone tissue regeneration. PMID:24441614

  11. Influence of mechanical properties of alginate-based substrates on the performance of Schwann cells in culture.

    PubMed

    Ning, Liqun; Xu, Yitong; Chen, Xiongbiao; Schreyer, David J

    2016-06-01

    In tissue engineering, artificial tissue scaffolds containing living cells have been studied for tissue repair and regeneration. Notably, the performance of these encapsulated-in-scaffolds cells in terms of cell viability, proliferation, and expression of function during and after the scaffold fabrication process, has not been well documented because of the influence of mechanical, chemical, and physical properties of the scaffold substrate materials. This paper presents our study on the influence of mechanical properties of alginate-based substrates on the performance of Schwann cells, which are the major glial cells of peripheral nervous system. Given the fact that alginate polysaccharide hydrogel has poor cell adhesion properties, in this study, we examined several types of cell-adhesion supplements and found that alginate covalently modified with RGD peptide provided improved cell proliferation and adhesion. We prepared alginate-based substrates for cell culture using varying alginate concentrations for altering their mechanical properties, which were confirmed by compression testing. Then, we examined the viability, proliferation, morphology, and expression of the extracellular matrix protein laminin of Schwann cells that were seeded on the surface of alginate-based substrates (or 2D culture) or encapsulated within alginate-based substrates (3D cultures), and correlated the examined cell performance to the alginate concentration (or mechanical properties) of hydrogel substrates. Our findings suggest that covalent attachment of RGD peptide can improve the success of Schwann cell encapsulation within alginate-based scaffolds, and provide guidance for regulating the mechanical properties of alginate-based scaffolds containing Schwann cells for applications in peripheral nervous system regeneration and repair. PMID:27012482

  12. Influence of mechanical properties of alginate-based substrates on the performance of Schwann cells in culture.

    PubMed

    Ning, Liqun; Xu, Yitong; Chen, Xiongbiao; Schreyer, David J

    2016-06-01

    In tissue engineering, artificial tissue scaffolds containing living cells have been studied for tissue repair and regeneration. Notably, the performance of these encapsulated-in-scaffolds cells in terms of cell viability, proliferation, and expression of function during and after the scaffold fabrication process, has not been well documented because of the influence of mechanical, chemical, and physical properties of the scaffold substrate materials. This paper presents our study on the influence of mechanical properties of alginate-based substrates on the performance of Schwann cells, which are the major glial cells of peripheral nervous system. Given the fact that alginate polysaccharide hydrogel has poor cell adhesion properties, in this study, we examined several types of cell-adhesion supplements and found that alginate covalently modified with RGD peptide provided improved cell proliferation and adhesion. We prepared alginate-based substrates for cell culture using varying alginate concentrations for altering their mechanical properties, which were confirmed by compression testing. Then, we examined the viability, proliferation, morphology, and expression of the extracellular matrix protein laminin of Schwann cells that were seeded on the surface of alginate-based substrates (or 2D culture) or encapsulated within alginate-based substrates (3D cultures), and correlated the examined cell performance to the alginate concentration (or mechanical properties) of hydrogel substrates. Our findings suggest that covalent attachment of RGD peptide can improve the success of Schwann cell encapsulation within alginate-based scaffolds, and provide guidance for regulating the mechanical properties of alginate-based scaffolds containing Schwann cells for applications in peripheral nervous system regeneration and repair.

  13. Alginate composites for bone tissue engineering: a review.

    PubMed

    Venkatesan, Jayachandran; Bhatnagar, Ira; Manivasagan, Panchanathan; Kang, Kyong-Hwa; Kim, Se-Kwon

    2015-01-01

    Bone is a complex and hierarchical tissue consisting of nano hydroxyapatite and collagen as major portion. Several attempts have been made to prepare the artificial bone so as to replace the autograft and allograft treatment. Tissue engineering is a promising approach to solve the several issues and is also useful in the construction of artificial bone with materials including polymer, ceramics, metals, cells and growth factors. Composites consisting of polymer-ceramics, best mimic the natural functions of bone. Alginate, an anionic polymer owing enormous biomedical applications, is gaining importance particularly in bone tissue engineering due to its biocompatibility and gel forming properties. Several composites such as alginate-polymer (PLGA, PEG and chitosan), alginate-protein (collagen and gelatin), alginate-ceramic, alginate-bioglass, alginate-biosilica, alginate-bone morphogenetic protein-2 and RGD peptides composite have been investigated till date. These alginate composites show enhanced biochemical significance in terms of porosity, mechanical strength, cell adhesion, biocompatibility, cell proliferation, alkaline phosphatase increase, excellent mineralization and osteogenic differentiation. Hence, alginate based composite biomaterials will be promising for bone tissue regeneration. This review will provide a broad overview of alginate preparation and its applications towards bone tissue engineering.

  14. Stability of alginate-immobilized algal cells

    SciTech Connect

    Dainty, A.L.; Goulding, K.H.; Robinson, P.K.; Simpkins, I; Trevan, M.D.

    1986-01-01

    Investigations were carried out using immobilized Chlorella cells to determine the diameter, compressibility, tolerance to phosphate chelation, and ability to retain algal cells during incubation of various alginate beads. These physical bead-characteristics were affected by a variety of interactive factors, including multivalent cation type (hardening agent) and cell, cation, and alginate concentration, the latter exhibiting a predominant influence. The susceptibility of alginate beads to phosphate chelation involved a complex interaction of cation type, concentration, and pH of phosphate solution. A scale of response ranging from gel swelling to gel shrinking was observed for a range of conditions. However, stable Ca alginate beads were maintained in incubation media with a pH of 5.5 and a phosphate concentration of 5 micro M. A preliminary investigation into cell leakage from the beads illustrated the importance of maintaining a stable gel structure and limiting cell growth to reduce leakage.

  15. 21 CFR 201.319 - Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including, but not limited to...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium polycarbophil..., and hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium polycarbophil... including, but not limited to, agar, alginic acid, calcium polycarbophil, carboxymethylcellulose...

  16. 21 CFR 201.319 - Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including, but not limited to...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium polycarbophil..., and hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium polycarbophil... including, but not limited to, agar, alginic acid, calcium polycarbophil, carboxymethylcellulose...

  17. Stability of alginate microbead properties in vitro

    PubMed Central

    Moya, Monica L.; Morley, Michael; Khanna, Omaditya; Opara, Emmanuel C.

    2013-01-01

    Alginate microbeads have been investigated clinically for a number of therapeutic interventions, including drug delivery for treatment of ischemic tissues, cell delivery for tissue regeneration, and islet encapsulation as a therapy for type I diabetes. The physical properties of the microbeads play an important role in regulating cell behavior, protein release, and biological response following implantation. In this research alginate microbeads were synthesized, varying composition (mannuronic acid to guluronic acid ratio), concentration of alginate and needle gauge size. Following synthesis, the size, volume fraction, and morphometry of the beads were quantified. In addition, these properties were monitored over time in vitro in the presence of varying calcium levels in the microenvironment. The initial volume available for solute diffusion increased with alginate concentration and mannuronic (M) acid content, and bead diameter decreased with M content but increased with needle diameter. Interestingly, microbeads eroded completely in saline in less than 3 weeks regardless of synthesis conditions much faster than what has been observed in vivo. However, microbead stability was increased by the addition of calcium in the culture medium. Beads synthesized with low alginate concentration and high G content exhibited a more rapid change in physical properties even in the presence of calcium. These data suggest that temporal variations in the physical characteristics of alginate microbeads can occur in vitro depending on synthesis conditions and microbead environment. The results presented here will assist in optimizing the design of the materials for clinical application in drug delivery and cell therapy. PMID:22350778

  18. ERK Signals: Scaffolding Scaffolds?

    PubMed Central

    Casar, Berta; Crespo, Piero

    2016-01-01

    ERK1/2 MAP Kinases become activated in response to multiple intra- and extra-cellular stimuli through a signaling module composed of sequential tiers of cytoplasmic kinases. Scaffold proteins regulate ERK signals by connecting the different components of the module into a multi-enzymatic complex by which signal amplitude and duration are fine-tuned, and also provide signal fidelity by isolating this complex from external interferences. In addition, scaffold proteins play a central role as spatial regulators of ERKs signals. In this respect, depending on the subcellular localization from which the activating signals emanate, defined scaffolds specify which substrates are amenable to be phosphorylated. Recent evidence has unveiled direct interactions among different scaffold protein species. These scaffold-scaffold macro-complexes could constitute an additional level of regulation for ERK signals and may serve as nodes for the integration of incoming signals and the subsequent diversification of the outgoing signals with respect to substrate engagement. PMID:27303664

  19. Novel crosslinked alginate/hyaluronic acid hydrogels for nerve tissue engineering

    NASA Astrophysics Data System (ADS)

    Wang, Min-Dan; Zhai, Peng; Schreyer, David J.; Zheng, Ruo-Shi; Sun, Xiao-Dan; Cui, Fu-Zhai; Chen, Xiong-Biao

    2013-09-01

    Artificial tissue engineering scaffolds can potentially provide support and guidance for the regrowth of severed axons following nerve injury. In this study, a hybrid biomaterial composed of alginate and hyaluronic acid (HA) was synthesized and characterized in terms of its suitability for covalent modification, biocompatibility for living Schwann cells and feasibility to construct three dimensional (3D) scaffolds. Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calciumions that ionically crosslink alginate. Amide formation was found to be dependent on the concentrations of carbodiimide and calcium chloride. The double-crosslinked composite hydrogels display biocompatibility that is comparable to simple HA hydrogels, allowing for Schwann cell survival and growth. No significant difference was found between composite hydrogels made from different ratios of alginate and HA. A 3D BioPlotter™ rapid prototyping system was used to fabricate 3D scaffolds. The result indicated that combining HA with alginate facilitated the fabrication process and that 3D scaffolds with porous inner structure can be fabricated from the composite hydrogels, but not from HA alone. This information provides a basis for continuing in vitro and in vivo tests of the suitability of alginate/HA hydrogel as a biomaterial to create living cell scaffolds to support nerve regeneration.

  20. Automated quantitative assessment of three-dimensional bioprinted hydrogel scaffolds using optical coherence tomography

    PubMed Central

    Wang, Ling; Xu, Mingen; Zhang, LieLie; Zhou, QingQing; Luo, Li

    2016-01-01

    Reconstructing and quantitatively assessing the internal architecture of opaque three-dimensional (3D) bioprinted hydrogel scaffolds is difficult but vital to the improvement of 3D bioprinting techniques and to the fabrication of functional engineered tissues. In this study, swept-source optical coherence tomography was applied to acquire high-resolution images of hydrogel scaffolds. Novel 3D gelatin/alginate hydrogel scaffolds with six different representative architectures were fabricated using our 3D bioprinting system. Both the scaffold material networks and the interconnected flow channel networks were reconstructed through volume rendering and binarisation processing to provide a 3D volumetric view. An image analysis algorithm was developed based on the automatic selection of the spatially-isolated region-of–interest. Via this algorithm, the spatially-resolved morphological parameters including pore size, pore shape, strut size, surface area, porosity, and interconnectivity were quantified precisely. Fabrication defects and differences between the designed and as-produced scaffolds were clearly identified in both 2D and 3D; the locations and dimensions of each of the fabrication defects were also defined. It concludes that this method will be a key tool for non-destructive and quantitative characterization, design optimisation and fabrication refinement of 3D bioprinted hydrogel scaffolds. Furthermore, this method enables investigation into the quantitative relationship between scaffold structure and biological outcome. PMID:27231597

  1. Bioacetylation of Seaweed Alginate

    PubMed Central

    Lee, J. W.; Day, D. F.

    1995-01-01

    Seaweed alginate was acetylated by intact, resting cells of Pseudomonas syringae ATCC 19304. Maximum acetylation of this polymer occurred at a pH of 6.0 and a temperature of 25 deg C. Aeration and gluconic acid were required for an optimal reaction. A reactor which contained carbon-immobilized cells was constructed to continuously acetylate alginate. The maximal yield of acetylation was about 90%, and the half-life of this system was 6.5 days. PMID:16534934

  2. Gingival Mesenchymal Stem Cell (GMSC) Delivery System Based on RGD-Coupled Alginate Hydrogel with Antimicrobial Properties: A Novel Treatment Modality for Peri-Implantitis

    PubMed Central

    Diniz, Ivana M. A.; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H.; Moshaverinia, Maryam; Chee, Daniel; Marques, Márcia M.; Shi, Songtao; Moshaverinia, Alireza

    2015-01-01

    Purpose Peri-implantitis is one of the most common inflammatory complications in dental implantology. Similar to periodontitis, in peri-implantitis, destructive inflammatory changes take place in the tissues surrounding a dental implant. Bacterial flora at the failing implant sites resemble the pathogens in periodontal disease and consist of Gram-negative anaerobic bacteria including Aggregatibacter actinomycetemcomitans (Aa). Here we demonstrate the effectiveness of a silver lactate (SL)-containing RGD-coupled alginate hydrogel scaffold as a promising stem cell delivery vehicle with antimicrobial properties. Materials and Methods Gingival mesenchymal stem cells (GMSCs) or human bone marrow mesenchymal stem cells (hBMMSCs) were encapsulated in SL-loaded alginate hydrogel microspheres. Stem cell viability, proliferation, and osteo-differentiation capacity were analyzed. Results Our results showed that SL exhibited antimicrobial properties against Aa in a dose-dependent manner, with 0.50 mg/ml showing the greatest antimicrobial properties while still maintaining cell viability. At this concentration, SL-containing alginate hydrogel was able to inhibit Aa on the surface of Ti discs and significantly reduce the bacterial load in Aa suspensions. Silver ions were effectively released from the SL-loaded alginate microspheres for up to 2 weeks. Osteogenic differentiation of GMSCs and hBMMSCs encapsulated in the SL-loaded alginate microspheres were confirmed by the intense mineral matrix deposition and high expression of osteogenesis-related genes. Conclusion Taken together, our findings confirm that GMSCs encapsulated in RGD-modified alginate hydrogel containing SL show promise for bone tissue engineering with antimicrobial properties against Aa bacteria in vitro. PMID:26216081

  3. Alginate-polymethacrylate hybrid hydrogels with double ionic and covalent network for tissue engineering

    NASA Astrophysics Data System (ADS)

    Schizzi, I.; Utzeri, R.; Castellano, M.; Stagnaro, P.

    2016-05-01

    Hydrogels based on alginates are very promising candidates to realize scaffolds for tissue engineering. Indeed, alginate hydrogels are able to mimic the extracellular matrix (ECM) thus promoting in vitro and/or in vivo cell growth; moreover, their capability of giving rise to highly porous structures can specifically favor the osteochondral tissue regeneration. However, mechanical properties of polymeric hydrogels are often inadequate to endow the final constructs with the required characteristics of elasticity and toughness. Here alginate/polymethacrylate hybrid hydrogels, with a suitable porous structure and characterized by a double network, ionic (from alginate) and covalent (from polymethacrylate) were designed and realized. The mechanical performance of these hybrid materials resulted, as expected, improved due to the double interconnected network, where the alginate portion provides the appropriate micro-environment mimicking the ECM, whereas the polymethacrylate portion acts as a reinforce.

  4. Mechanical properties of alginate hydrogels manufactured using external gelation.

    PubMed

    Kaklamani, Georgia; Cheneler, David; Grover, Liam M; Adams, Michael J; Bowen, James

    2014-08-01

    Alginate hydrogels are commonly used in biomedical applications such as scaffolds for tissue engineering, drug delivery, and as a medium for cell immobilisation. Multivalent cations are often employed to create physical crosslinks between carboxyl and hydroxyl moieties on neighbouring polysaccharide chains, creating hydrogels with a range of mechanical properties. This work describes the manufacture and characterisation of sodium alginate hydrogels using the divalent cations Mg(2+), Ca(2+) and Sr(2+) to promote gelation via non-covalent crosslinks. Gelation time and Young׳s modulus are characterised as a function of cation and alginate concentrations. The implications of this work towards the use of environmental elasticity to control stem cell differentiation are discussed.

  5. A prospective comparison of alginate-hydrogel with standard medical therapy to determine impact on functional capacity and clinical outcomes in patients with advanced heart failure (AUGMENT-HF trial)

    PubMed Central

    Anker, Stefan D.; Coats, Andrew J.S.; Cristian, Gabriel; Dragomir, Dinu; Pusineri, Enrico; Piredda, Massimo; Bettari, Luca; Dowling, Robert; Volterrani, Maurizio; Kirwan, Bridget-Anne; Filippatos, Gerasimos; Mas, Jean-Louis; Danchin, Nicolas; Solomon, Scott D.; Lee, Randall J.; Ahmann, Frank; Hinson, Andy; Sabbah, Hani N.; Mann, Douglas L.

    2015-01-01

    Aims AUGMENT-HF was an international, multi-centre, prospective, randomized, controlled trial to evaluate the benefits and safety of a novel method of left ventricular (LV) modification with alginate-hydrogel. Methods Alginate-hydrogel is an inert permanent implant that is directly injected into LV heart muscle and serves as a prosthetic scaffold to modify the shape and size of the dilated LV. Patients with advanced chronic heart failure (HF) were randomized (1 : 1) to alginate-hydrogel (n = 40) in combination with standard medical therapy or standard medical therapy alone (Control, n = 38). The primary endpoint of AUGMENT-HF was the change in peak VO2 from baseline to 6 months. Secondary endpoints included changes in 6-min walk test (6MWT) distance and New York Heart Association (NYHA) functional class, as well as assessments of procedural safety. Results Enrolled patients were 63 ± 10 years old, 74% in NYHA functional class III, had a LV ejection fraction of 26 ± 5% and a mean peak VO2 of 12.2 ± 1.8 mL/kg/min. Thirty-five patients were successfully treated with alginate-hydrogel injections through a limited left thoracotomy approach without device-related complications; the 30-day surgical mortality was 8.6% (3 deaths). Alginate-hydrogel treatment was associated with improved peak VO2 at 6 months—treatment effect vs. Control: +1.24 mL/kg/min (95% confidence interval 0.26–2.23, P = 0.014). Also 6MWT distance and NYHA functional class improved in alginate-hydrogel-treated patients vs. Control (both P < 0.001). Conclusion Alginate-hydrogel in addition to standard medical therapy for patients with advanced chronic HF was more effective than standard medical therapy alone for improving exercise capacity and symptoms. The results of AUGMENT-HF provide proof of concept for a pivotal trial. Trial Registration Number NCT01311791. PMID:26082085

  6. Towards antimicrobial yet bioactive Cu-alginate hydrogels.

    PubMed

    Madzovska-Malagurski, I; Vukasinovic-Sekulic, M; Kostic, D; Levic, S

    2016-06-15

    The simplest approach to enhance alginate hydrogel characteristics and functional properties is to replace the calcium in the process of alginate gelation with other metallic ions which are essential for living systems. Gelling of alginate with other ions and using modern encapsulation techniques can provide new delivery systems with required properties. Hence, in this study Cu-alginate hydrogels in the form of microbeads were produced by electrostatic extrusion using gelling solutions with Cu(II) concentrations in the range 13.5-270 mM and comprehensively characterized in vitro. The variation of gelling solution concentration influenced the microbead Cu(II) content, size, biomechanical properties, Cu(II) release and subsequently potential biomedical application. The formulations chosen for biomedical evaluation showed potential for antimicrobial and tissue engineering applications. Microbeads with higher Cu(II) loading (~100 μmol g(-1)) induced immediate bactericidal effects against Escherichia coli and Staphylococcus aureus. Conversely, Cu(II) release from microbeads with the Cu(II) content of ~60 μmol g(-1) was slower and they were suitable for promoting and maintaining chondrogenic phenotype of bovine calf chondrocytes in 3D culture. Results of this study have shown possibilities for tuning Cu-alginate properties for potential biomedical applications such as antimicrobial wound dressings, tissue engineering scaffolds or articular cartilage implants.

  7. Evaluation of sodium alginate for bone marrow cell tissue engineering.

    PubMed

    Wang, L; Shelton, R M; Cooper, P R; Lawson, M; Triffitt, J T; Barralet, J E

    2003-09-01

    Sodium alginate has applications as a material for the encapsulation and immobilisation of a variety of cell types for immunoisolatory and biochemical processing applications. It forms a biodegradable gel when crosslinked with calcium ions and it has been exploited in cartilage tissue engineering since chondrocytes do not dedifferentiate when immobilised in it. Despite its attractive properties of degradability, ease of processing and cell immobilisation, there is little work demonstrating the efficacy of alginate gel as a substrate for cell proliferation, except when RGD is modified. In this study we investigated the ability of rat bone marrow cells to proliferate and differentiate on alginates of differing composition and purity. The mechanical properties of the gels were investigated. It was found that high purity and high G-type alginate retained 27% of its initial strength after 12 days in culture and that comparable levels of proliferation were observed on this material and tissue culture plastic. Depending on composition, calcium crosslinked alginate can act as a substrate for rat marrow cell proliferation and has potential for use as 3D degradable scaffold.

  8. Evaluation of an alginate-gelatine crosslinked hydrogel for bioplotting.

    PubMed

    Zehnder, Tobias; Sarker, Bapi; Boccaccini, Aldo R; Detsch, Rainer

    2015-04-08

    Using additive manufacturing to create hydrogel scaffolds which incorporate homogeneously distributed, immobilized cells in the context of biofabrication approaches represents an emerging and expanding field in tissue engineering. Applying hydrogels for additive manufacturing must consider the material processing properties as well as their influence on the immobilized cells. In this work alginate-dialdehyde (ADA), a partially oxidized alginate, was used as a basic material to improve the physico-chemical properties of the hydrogel for cell immobilization. At first, the processing ability of the gel using a bioplotter and the compatibility of the process with MG-63 osteoblast like cells were investigated. The metabolic and mitochondrial activities increased at the beginning of the incubation period and they balanced at a relatively high level after 14-28 days of incubation. During this incubation period the release of vascular endothelial growth factor-A also increased. After 28 days of incubation the cell morphology showed a spreading morphology and cells were seen to move out of the scaffold struts covering the whole scaffold structure. The reproducible processing capability of alginate-gelatine (ADA-GEL) and the compatibility with MG-63 cells were proven, thus the ADA-GEL material is highlighted as a promising matrix for applications in biofabrication.

  9. Scaffolds in Tendon Tissue Engineering

    PubMed Central

    Longo, Umile Giuseppe; Lamberti, Alfredo; Petrillo, Stefano; Maffulli, Nicola; Denaro, Vincenzo

    2012-01-01

    Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing tendon disorders. Tissue engineering strategies to improve tendon repair healing include the use of scaffolds, growth factors, cell seeding, or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Available scaffolds for tendon repair include both biological scaffolds, obtained from mammalian tissues, and synthetic scaffolds, manufactured from chemical compounds. Preliminary studies support the idea that scaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potential. However, available data are lacking to allow definitive conclusion on the use of scaffolds for tendon augmentation. We review the current basic science and clinical understanding in the field of scaffolds and tissue engineering for tendon repair. PMID:22190961

  10. Wound Dressing Model of Human Umbilical Cord Mesenchymal Stem Cells-Alginates Complex Promotes Skin Wound Healing by Paracrine Signaling

    PubMed Central

    Yang, Huachao; Tang, Zhenrui; Long, Gang; Huang, Wen

    2016-01-01

    Purpose. To probe growth characteristics of human umbilical cord mesenchymal stem cells (hUCMSCs) cultured with alginate gel scaffolds, and to explore feasibility of wound dressing model of hUCMSCs-alginates compound. Methods. hUCMSCs were isolated, cultured, and identified in vitro. Then cells were cultivated in 100 mM calcium alginate gel, and the capacity of proliferation and migration and the expression of vascular endothelial growth factors (VEGF) were investigated regularly. Wound dressing model of hUCMSCs-alginate gel mix was transplanted into Balb/c mice skin defects. Wound healing rate and immunohistochemistry were examined. Results. hUCMSCs grew well but with little migration ability in the alginate gel. Compared with control group, a significantly larger cell number and more VEGF expression were shown in the gel group after culturing for 3–6 days (P < 0.05). In addition, a faster skin wound healing rate with more neovascularization was observed in the hUCMSCs-alginate gel group than in control groups at 15th day after surgery (P < 0.05). Conclusion. hUCMSCs can proliferate well and express massive VEGF in calcium alginate gel porous scaffolds. Wound dressing model of hUCMSCs-alginate gel mix can promote wound healing through paracrine signaling. PMID:26880953

  11. Utilizing Core–Shell Fibrous Collagen-Alginate Hydrogel Cell Delivery System for Bone Tissue Engineering

    PubMed Central

    Perez, Roman A.; Kim, Meeju; Kim, Tae-Hyun; Kim, Joong-Hyun; Lee, Jae Ho; Park, Jeong-Hui; Knowles, Jonathan C.

    2014-01-01

    Three-dimensional matrices that encapsulate and deliver stem cells with defect-tuned formulations are promising for bone tissue engineering. In this study, we designed a novel stem cell delivery system composed of collagen and alginate as the core and shell, respectively. Mesenchymal stem cells (MSCs) were loaded into the collagen solution and then deposited directly into a fibrous structure while simultaneously sheathing with alginate using a newly designed core–shell nozzle. Alginate encapsulation was achieved by the crosslinking within an adjusted calcium-containing solution that effectively preserved the continuous fibrous structure of the inner cell-collagen part. The constructed hydrogel carriers showed a continuous fiber with a diameter of ∼700–1000 μm for the core and 200–500 μm for the shell area, which was largely dependent on the alginate concentration (2%–5%) as well as the injection rate (20–80 mL/h). The water uptake capacity of the core–shell carriers was as high as 98%, which could act as a pore channel to supply nutrients and oxygen to the cells. Degradation of the scaffolds showed a weight loss of ∼22% at 7 days and ∼43% at 14 days, suggesting a possible role as a degradable tissue-engineered construct. The MSCs encapsulated within the collagen core showed excellent viability, exhibiting significant cellular proliferation up to 21 days with levels comparable to those observed in the pure collagen gel matrix used as a control. A live/dead cell assay also confirmed similar percentages of live cells within the core–shell carrier compared to those in the pure collagen gel, suggesting the carrier was cell compatible and was effective for maintaining a cell population. Cells allowed to differentiate under osteogenic conditions expressed high levels of bone-related genes, including osteocalcin, bone sialoprotein, and osteopontin. Further, when the core–shell fibrous carriers were implanted in a rat calvarium defect, the bone

  12. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate is prepared by...

  13. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium alginate. 184.1724 Section 184.1724 Food and... Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate...

  14. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Potassium alginate...

  15. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Calcium alginate is prepared...

  16. Preparation of in situ hardening composite microcarriers: calcium phosphate cement combined with alginate for bone regeneration.

    PubMed

    Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C; Kim, Hae-Won

    2014-03-01

    Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution = 0.8-1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement-alginate microcarriers under moist conditions due to the conversion of the α-tricalcium phosphate phase in the calcium phosphate cement into a carbonate-hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement-alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone.

  17. A Semi-Degradable Composite Scaffold for Articular Cartilage Defects

    PubMed Central

    Scholten, Paul M.; Ng, Kenneth W.; Joh, Kiwon; Serino, Lorenzo P.; Warren, Russell F.; Torzilli, Peter A.; Maher, Suzanne A.

    2010-01-01

    Few options exist to replace or repair damaged articular cartilage. The optimal solution that has been suggested is a scaffold that can carry load and integrate with surrounding tissues; but such a construct has thus far been elusive. The objectives of this study were to manufacture and characterize a non-degradable hydrated scaffold. Our hypothesis was that the polymer content of the scaffold can be used to control its mechanical properties, while an internal porous network augmented with biological agents can facilitate integration with the host tissue. Using a two-step water-in-oil emulsion process a porous poly-vinyl alcohol (PVA) hydrogel scaffold combined with alginate microspheres was manufactured. The scaffold had a porosity of 11–30% with pore diameters of 107–187 μm, which readily allowed for movement of cells through the scaffold. Alginate microparticles were evenly distributed through the scaffold and allowed for the slow release of biological factors. The elastic modulus (Es) and Poisson’s ratio (υ), Aggregate modulus (Ha) and dynamic modulus (ED) of the scaffold were significantly affected by % PVA, as it varied from 10% to 20% wt/vol. Es and υ were similar to that of articular cartilage for both polymer concentrations, while Ha and ED were similar to that of cartilage only at 20% PVA. The ability to control scaffold mechanical properties, while facilitating cellular migration suggest that this scaffold is a potentially viable candidate for the functional replacement of cartilage defects. PMID:21308980

  18. Mathematical model for predicting topographical properties of poly (ε-caprolactone) melt electrospun scaffolds including the effects of temperature and linear transitional speed

    NASA Astrophysics Data System (ADS)

    Ko, Junghyuk; Khadem Mohtaram, Nima; Lee, Patrick C.; Willerth, Stephanie M.; Jun, Martin B. G.

    2015-04-01

    Melt electrospinning can be used to fabricate various fibrous biomaterial scaffolds with a range of mechanical properties and varying topographical properties for different applications such as tissue scaffold and filtration and etc, making it a powerful technique. Engineering the topography of such electrospun microfibers can be easily done by tuning the operational parameters of this process. Recent experimental studies have shown promising results for fabricating various topographies, but there is no body of work that focuses on using mathematical models of this technique to further understand the effect of operational parameters on these properties of microfiber scaffolds. In this study, we developed a novel mathematical model using numerical simulations to demonstrate the effect of temperature, feed rate and flow rate on controlling topographical properties such as fiber diameter of these spun fibrous scaffolds. These promising modelling results are also compared to our previous and current experimental results. Overall, we show that our novel mathematical model can predict the topographical properties affected by key operational parameters such as change in temperature, flow rate and feed rate, and this model could serve as a promising strategy for the controlling of topographical properties of such structures for different applications.

  19. Dual drug-loaded nanoparticles on self-integrated scaffold for controlled delivery

    PubMed Central

    Bennet, Devasier; Marimuthu, Mohana; Kim, Sanghyo; An, Jeongho

    2012-01-01

    Antioxidant (quercetin) and hypoglycemic (voglibose) drug-loaded poly-D,L-lactideco-glycolide nanoparticles were successfully synthesized using the solvent evaporation method. The dual drug-loaded nanoparticles were incorporated into a scaffold film using a solvent casting method, creating a controlled transdermal drug-delivery system. Key features of the film formulation were achieved utilizing several ratios of excipients, including polyvinyl alcohol, polyethylene glycol, hyaluronic acid, xylitol, and alginate. The scaffold film showed superior encapsulation capability and swelling properties, with various potential applications, eg, the treatment of diabetes-associated complications. Structural and light scattering characterization confirmed a spherical shape and a mean particle size distribution of 41.3 nm for nanoparticles in the scaffold film. Spectroscopy revealed a stable polymer structure before and after encapsulation. The thermoresponsive swelling properties of the film were evaluated according to temperature and pH. Scaffold films incorporating dual drug-loaded nanoparticles showed remarkably high thermoresponsivity, cell compatibility, and ex vivo drug-release behavior. In addition, the hybrid film formulation showed enhanced cell adhesion and proliferation. These dual drug-loaded nanoparticles incorporated into a scaffold film may be promising for development into a transdermal drug-delivery system. PMID:22888222

  20. Novel synthesis strategies for natural polymer and composite biomaterials as potential scaffolds for tissue engineering

    PubMed Central

    Ko, Hsu-Feng; Sfeir, Charles; Kumta, Prashant N.

    2010-01-01

    Recent developments in tissue engineering approaches frequently revolve around the use of three-dimensional scaffolds to function as the template for cellular activities to repair, rebuild and regenerate damaged or lost tissues. While there are several biomaterials to select as three-dimensional scaffolds, it is generally agreed that a biomaterial to be used in tissue engineering needs to possess certain material characteristics such as biocompatibility, suitable surface chemistry, interconnected porosity, desired mechanical properties and biodegradability. The use of naturally derived polymers as three-dimensional scaffolds has been gaining widespread attention owing to their favourable attributes of biocompatibility, low cost and ease of processing. This paper discusses the synthesis of various polysaccharide-based, naturally derived polymers, and the potential of using these biomaterials to serve as tissue engineering three-dimensional scaffolds is also evaluated. In this study, naturally derived polymers, specifically cellulose, chitosan, alginate and agarose, and their composites, are examined. Single-component scaffolds of plain cellulose, plain chitosan and plain alginate as well as composite scaffolds of cellulose–alginate, cellulose–agarose, cellulose–chitosan, chitosan–alginate and chitosan–agarose are synthesized, and their suitability as tissue engineering scaffolds is assessed. It is shown that naturally derived polymers in the form of hydrogels can be synthesized, and the lyophilization technique is used to synthesize various composites comprising these natural polymers. The composite scaffolds appear to be sponge-like after lyophilization. Scanning electron microscopy is used to demonstrate the formation of an interconnected porous network within the polymeric scaffold following lyophilization. It is also established that HeLa cells attach and proliferate well on scaffolds of cellulose, chitosan or alginate. The synthesis protocols reported

  1. Mimicking Metastases Including Tumor Stroma: A New Technique to Generate a Three-Dimensional Colorectal Cancer Model Based on a Biological Decellularized Intestinal Scaffold

    PubMed Central

    Nietzer, Sarah; Baur, Florentin; Sieber, Stefan; Hansmann, Jan; Schwarz, Thomas; Stoffer, Carolin; Häfner, Heide; Gasser, Martin; Waaga-Gasser, Ana Maria; Walles, Heike

    2016-01-01

    Tumor models based on cancer cell lines cultured two-dimensionally (2D) on plastic lack histological complexity and functionality compared to the native microenvironment. Xenogenic mouse tumor models display higher complexity but often do not predict human drug responses accurately due to species-specific differences. We present here a three-dimensional (3D) in vitro colon cancer model based on a biological scaffold derived from decellularized porcine jejunum (small intestine submucosa+mucosa, SISmuc). Two different cell lines were used in monoculture or in coculture with primary fibroblasts. After 14 days of culture, we demonstrated a close contact of human Caco2 colon cancer cells with the preserved basement membrane on an ultrastructural level as well as morphological characteristics of a well-differentiated epithelium. To generate a tissue-engineered tumor model, we chose human SW480 colon cancer cells, a reportedly malignant cell line. Malignant characteristics were confirmed in 2D cell culture: SW480 cells showed higher vimentin and lower E-cadherin expression than Caco2 cells. In contrast to Caco2, SW480 cells displayed cancerous characteristics such as delocalized E-cadherin and nuclear location of β-catenin in a subset of cells. One central drawback of 2D cultures—especially in consideration of drug testing—is their artificially high proliferation. In our 3D tissue-engineered tumor model, both cell lines showed decreased numbers of proliferating cells, thus correlating more precisely with observations of primary colon cancer in all stages (UICC I-IV). Moreover, vimentin decreased in SW480 colon cancer cells, indicating a mesenchymal to epithelial transition process, attributed to metastasis formation. Only SW480 cells cocultured with fibroblasts induced the formation of tumor-like aggregates surrounded by fibroblasts, whereas in Caco2 cocultures, a separate Caco2 cell layer was formed separated from the fibroblast compartment beneath. To foster tissue

  2. Mimicking Metastases Including Tumor Stroma: A New Technique to Generate a Three-Dimensional Colorectal Cancer Model Based on a Biological Decellularized Intestinal Scaffold.

    PubMed

    Nietzer, Sarah; Baur, Florentin; Sieber, Stefan; Hansmann, Jan; Schwarz, Thomas; Stoffer, Carolin; Häfner, Heide; Gasser, Martin; Waaga-Gasser, Ana Maria; Walles, Heike; Dandekar, Gudrun

    2016-07-01

    Tumor models based on cancer cell lines cultured two-dimensionally (2D) on plastic lack histological complexity and functionality compared to the native microenvironment. Xenogenic mouse tumor models display higher complexity but often do not predict human drug responses accurately due to species-specific differences. We present here a three-dimensional (3D) in vitro colon cancer model based on a biological scaffold derived from decellularized porcine jejunum (small intestine submucosa+mucosa, SISmuc). Two different cell lines were used in monoculture or in coculture with primary fibroblasts. After 14 days of culture, we demonstrated a close contact of human Caco2 colon cancer cells with the preserved basement membrane on an ultrastructural level as well as morphological characteristics of a well-differentiated epithelium. To generate a tissue-engineered tumor model, we chose human SW480 colon cancer cells, a reportedly malignant cell line. Malignant characteristics were confirmed in 2D cell culture: SW480 cells showed higher vimentin and lower E-cadherin expression than Caco2 cells. In contrast to Caco2, SW480 cells displayed cancerous characteristics such as delocalized E-cadherin and nuclear location of β-catenin in a subset of cells. One central drawback of 2D cultures-especially in consideration of drug testing-is their artificially high proliferation. In our 3D tissue-engineered tumor model, both cell lines showed decreased numbers of proliferating cells, thus correlating more precisely with observations of primary colon cancer in all stages (UICC I-IV). Moreover, vimentin decreased in SW480 colon cancer cells, indicating a mesenchymal to epithelial transition process, attributed to metastasis formation. Only SW480 cells cocultured with fibroblasts induced the formation of tumor-like aggregates surrounded by fibroblasts, whereas in Caco2 cocultures, a separate Caco2 cell layer was formed separated from the fibroblast compartment beneath. To foster tissue

  3. Influence of structural load-bearing scaffolds on mechanical load- and BMP-2-mediated bone regeneration.

    PubMed

    McDermott, Anna M; Mason, Devon E; Lin, Angela S P; Guldberg, Robert E; Boerckel, Joel D

    2016-09-01

    A common design constraint in functional tissue engineering is that scaffolds intended for use in load-bearing sites possess similar mechanical properties to the replaced tissue. Here, we tested the hypothesis that in vivo loading would enhance bone morphogenetic protein-2 (BMP-2)-mediated bone regeneration in the presence of a load-bearing PLDL scaffold, whose pores and central core were filled with BMP-2-releasing alginate hydrogel. First, we evaluated the effects of in vivo mechanical loading on bone regeneration in the structural scaffolds. Second, we compared scaffold-mediated bone regeneration, independent of mechanical loading, with alginate hydrogel constructs, without the structural scaffold, that have been shown previously to facilitate in vivo mechanical stimulation of bone formation. Contrary to our hypothesis, mechanical loading had no effect on bone formation, distribution, or biomechanical properties in structural scaffolds. Independent of loading, the structural scaffolds reduced bone formation compared to non-structural alginate, particularly in regions in which the scaffold was concentrated, resulting in impaired functional regeneration. This is attributable to a combination of stress shielding by the scaffold and inhibition of cellular infiltration and tissue ingrowth. Collectively, these data question the necessity of scaffold similarity to mature tissue at the time of implantation and emphasize development of an environment conducive to cellular activation of matrix production and ultimate functional regeneration.

  4. Calcium signaling in response to fluid flow by chondrocytes in 3D alginate culture.

    PubMed

    Degala, Satish; Williams, Rebecca; Zipfel, Warren; Bonassar, Lawrence J

    2012-05-01

    Quantifying the effects of mechanical loading on the metabolic response of chondrocytes is difficult due to complicated structure of cartilage ECM and the coupled nature of the mechanical stimuli presented to the cells. In this study we describe the effects of fluid flow, particularly hydrostatic pressure and wall shear stress, on the Ca(2+) signaling response of bovine articular chondrocytes in 3D culture. Using well-established alginate hydrogel system to maintain spherical chondrocyte morphology, we altered solid volume fraction to change scaffold mechanics. Fluid velocities in the bulk of the scaffolds were directly measured via an optical technique and scaffold permeability and aggregate modulus was characterized to quantify the mechanical stimuli presented to cells. Ca(2+) signaling response to direct perfusion of chondrocyte-seeded scaffolds increased monotonically with flow rate and was found more directly dependent on fluid velocity rather than shear stress or hydrostatic pressure. Chondrocytes in alginate scaffolds responded to fluid flow at velocities and shear stresses 2-3 orders of magnitude lower than seen in previous monolayer studies. Our data suggest that flow-induced Ca(2+) signaling response of chondrocytes in alginate culture may be due to mechanical signaling pathways, which is influenced by the 3D nature of cell shape.

  5. Using Scaffolds in Problem-Based Hypermedia

    ERIC Educational Resources Information Center

    Su, Yuyan; Klein, James D.

    2010-01-01

    This study investigated the use of scaffolds in problem-based hypermedia. Three hundred and twelve undergraduate students enrolled in a computer literacy course worked in project teams to use a hypermedia PBL program focused on designing a personal computer. The PBL program included content scaffolds, metacognitive scaffolds, or no scaffolds.…

  6. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  7. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  8. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  9. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  10. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  11. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  12. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  13. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  14. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  15. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  16. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  17. Influence of amino acids, buffers, and ph on the γ-irradiation-induced degradation of alginates.

    PubMed

    Ulset, Ann-Sissel T; Mori, Hideki; Dalheim, Marianne Ø; Hara, Masayuki; Christensen, Bjørn E

    2014-12-01

    Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates' material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy.

  18. Microbial alginate production, modification and its applications

    PubMed Central

    Hay, Iain D; Rehman, Zahid Ur; Moradali, M Fata; Wang, Yajie; Rehm, Bernd H A

    2013-01-01

    Alginate is an important polysaccharide used widely in the food, textile, printing and pharmaceutical industries for its viscosifying, and gelling properties. All commercially produced alginates are isolated from farmed brown seaweeds. These algal alginates suffer from heterogeneity in composition and material properties. Here, we will discuss alginates produced by bacteria; the molecular mechanisms involved in their biosynthesis; and the potential to utilize these bacterially produced or modified alginates for high-value applications where defined material properties are required. PMID:24034361

  19. Sustained Delivery of Bioactive GDNF from Collagen and Alginate-Based Cell-Encapsulating Gel Promoted Photoreceptor Survival in an Inherited Retinal Degeneration Model.

    PubMed

    Wong, Francisca S Y; Wong, Calvin C H; Chan, Barbara P; Lo, Amy C Y

    2016-01-01

    Encapsulated-cell therapy (ECT) is an attractive approach for continuously delivering freshly synthesized therapeutics to treat sight-threatening posterior eye diseases, circumventing repeated invasive intravitreal injections and improving local drug availability clinically. Composite collagen-alginate (CAC) scaffold contains an interpenetrating network that integrates the physical and biological merits of its constituents, including biocompatibility, mild gelling properties and availability. However, CAC ECT properties and performance in the eye are not well-understood. Previously, we reported a cultured 3D CAC system that supported the growth of GDNF-secreting HEK293 cells with sustainable GDNF delivery. Here, the system was further developed into an intravitreally injectable gel with 1x104 or 2x105 cells encapsulated in 2mg/ml type I collagen and 1% alginate. Gels with lower alginate concentration yielded higher initial cell viability but faster spheroid formation while increasing initial cell density encouraged cell growth. Continuous GDNF delivery was detected in culture and in healthy rat eyes for at least 14 days. The gels were well-tolerated with no host tissue attachment and contained living cell colonies. Most importantly, gel-implanted in dystrophic Royal College of Surgeons rat eyes for 28 days retained photoreceptors while those containing higher initial cell number yielded better photoreceptor survival. CAC ECT gels offers flexible system design and is a potential treatment option for posterior eye diseases. PMID:27441692

  20. Sustained Delivery of Bioactive GDNF from Collagen and Alginate-Based Cell-Encapsulating Gel Promoted Photoreceptor Survival in an Inherited Retinal Degeneration Model

    PubMed Central

    Chan, Barbara P.; Lo, Amy C. Y.

    2016-01-01

    Encapsulated-cell therapy (ECT) is an attractive approach for continuously delivering freshly synthesized therapeutics to treat sight-threatening posterior eye diseases, circumventing repeated invasive intravitreal injections and improving local drug availability clinically. Composite collagen-alginate (CAC) scaffold contains an interpenetrating network that integrates the physical and biological merits of its constituents, including biocompatibility, mild gelling properties and availability. However, CAC ECT properties and performance in the eye are not well-understood. Previously, we reported a cultured 3D CAC system that supported the growth of GDNF-secreting HEK293 cells with sustainable GDNF delivery. Here, the system was further developed into an intravitreally injectable gel with 1x104 or 2x105 cells encapsulated in 2mg/ml type I collagen and 1% alginate. Gels with lower alginate concentration yielded higher initial cell viability but faster spheroid formation while increasing initial cell density encouraged cell growth. Continuous GDNF delivery was detected in culture and in healthy rat eyes for at least 14 days. The gels were well-tolerated with no host tissue attachment and contained living cell colonies. Most importantly, gel-implanted in dystrophic Royal College of Surgeons rat eyes for 28 days retained photoreceptors while those containing higher initial cell number yielded better photoreceptor survival. CAC ECT gels offers flexible system design and is a potential treatment option for posterior eye diseases. PMID:27441692

  1. Calcium-Alginate Hydrogel-Encapsulated Fibroblasts Provide Sustained Release of Vascular Endothelial Growth Factor

    PubMed Central

    Hunt, Nicola C.; Shelton, Richard M.; Henderson, Deborah J.

    2013-01-01

    Vascularization of engineered or damaged tissues is essential to maintain cell viability and proper tissue function. Revascularization of the left ventricle (LV) of the heart after myocardial infarction is particularly important, since hypoxia can give rise to chronic heart failure due to inappropriate remodeling of the LV after death of cardiomyocytes (CMs). Fibroblasts can express vascular endothelial growth factor (VEGF), which plays a major role in angiogenesis and also acts as a chemoattractant and survival factor for CMs and cardiac progenitors. In this in vitro model study, mouse NIH 3T3 fibroblasts encapsulated in 2% w/v Ca-alginate were shown to remain viable for 150 days. Semiquantitative reverse transcription–polymerase chain reaction and immunohistochemistry demonstrated that over 21 days of encapsulation, fibroblasts continued to express VEGF, while enzyme-linked immunosorbent assay showed that there was sustained release of VEGF from the Ca-alginate during this period. The scaffold degraded gradually over the 21 days, without reduction in volume. Cells released from the Ca-alginate at 7 and 21 days as a result of scaffold degradation were shown to retain viability, to adhere to fibronectin in a normal manner, and continue to express VEGF, demonstrating their potential to further contribute to maintenance of cardiac function after scaffold degradation. This model in vitro study therefore demonstrates that fibroblasts encapsulated in Ca-alginate provide sustained release of VEGF. PMID:23082964

  2. Osteogenic behavior of alginate encapsulated bone marrow stromal cells: an in vitro study.

    PubMed

    Abbah, S A; Lu, W W; Chan, D; Cheung, K M C; Liu, W G; Zhao, F; Li, Z Y; Leong, J C Y; Luk, K D K

    2008-05-01

    Sodium alginate is a useful polymer for the encapsulation and immobilization of a variety of cells in tissue engineering because it is biocompatible, biodegradable and easy to process into injectable microbeads. Despite these properties, little is known of the efficacy of calcium cross-linked alginate gel beads as a biodegradable scaffold for osteogenic cell proliferation and differentiation. In this study, we investigated the ability of rabbit derived bone marrow cells (BMCs) to proliferate and differentiate in alginate microbeads and compared them with BMCs cultured in poly-L-lysine (PLL) coated microbeads and on conventional 2D plastic surfaces. Results show that levels of proliferation and differentiation in microbeads and on tissue culture plastics were comparable. Cell proliferation in microbeads however diminished after fortification with a coating layer of PLL. Maximum cell numbers observed were, 3.32 x 10(5) +/- 1.72 x 103; 3.11 x 10(5) +/- 1.52 x 10(3) and 3.28 x 10(5) +/- 1.21 x 10(3 ) for the uncoated, PLL coated and plastic surface groups respectively. Alkaline phosphatase and protein expressions reflected the stage of cell differentiation. We conclude that calcium cross-linked alginate microbeads can act as a scaffold for BMC proliferation and osteogenic differentiation and has potential for use as 3D degradable scaffold.

  3. Removal of uranium and other metals from wastewaters using calcium alginate and bacteria immobilized in calcium alginate

    SciTech Connect

    Gardner, K.R.; Montgomery, J.R.; Adams, D.J.

    1995-12-31

    Calcium alginate beads, containing immobilized bacteria, removed turanium and other metals from mine wastewaters. Batch tests using 2% calcium alginate beads with and without immobilized bacteria showed both were effective at removing uranium. Beads containing live and dead cells removed essentially the same amount of uranium and removed significantly more uranium than beads without bacteria. The bacteria-alginate system was used to treat waters containing 24.5 mg/L uranium and produced effluents containing 1.0 mg/L uranium in 1 hr and <0.1 mg/L uranium in 24 hr. Calcium alginate beads, with and without immobilized bacteria, also removed arsenic, selenium, and other metals from wastewaters. Bacteria investigated for immobilization in the alginate beads include Bacillus and Pseudomonas sp. A spray technique using an air nozzle has been tested to disperse the alginate into mine wastewater eliminating the bead-making process. Ninety-nine percent of the uranium was removed in less than 15 min contact.

  4. Behavior of encapsulated MG-63 cells in RGD and gelatine-modified alginate hydrogels.

    PubMed

    Grigore, Alexandra; Sarker, Bapi; Fabry, Ben; Boccaccini, Aldo R; Detsch, Rainer

    2014-08-01

    Achieving cell spreading and proliferation inside hydrogels that are compatible with microencapsulation technology represents a major challenge for tissue engineering scaffolding and for the development of three-dimensional cell culture models. In this study, microcapsules of 650-900 μm in diameter were fabricated from oxidized alginate covalently cross-linked with gelatine (AlGel). Schiff's base bond formed in AlGel, detected by Fourier transform infrared spectroscopy, which confirmed the cross-linking of oxidized alginate with gelatine. Biological properties of alginate based hydrogels were studied by comparing the viability and morphology of MG-63 osteosarcoma cells encapsulated in gelatine and RGD-modified alginate. We hypothesized that the presence of gelatine and RGD will support cell adhesion and spreading inside the microcapsules and finally, also vascular endothelial growth factor (VEGF) secretion. After 4 days of incubation, cells formed extensive cortical protrusions and after 2 weeks they proliferated, migrated, and formed cellular networks through the AlGel material. In contrast, cells encapsulated in pure alginate and in RGD-modified alginate formed spherical aggregates with limited cell mobility and VEGF secretion. Metabolic activity was doubled after 5 days of incubation, making AlGel a promising material for cell encapsulation.

  5. Hydroxyapatite-reinforced collagen tissue engineering scaffolds

    NASA Astrophysics Data System (ADS)

    Kane, Robert J.

    Scaffolds have been fabricated from a wide variety of materials and most have showed some success, either as bone graft substitutes or as tissue engineering scaffolds. However, all current scaffold compositions and architectures suffer from one or more flaws including poor mechanical properties, lack of biological response, nondegradability, or a scaffold architecture not conducive to osteointegration. Biomimetic approaches to scaffold design using the two main components of bone tissue, collagen and hydroxyapatite, resulted in scaffolds with superior biological properties but relatively poor mechanical properties and scaffold architecture. It was hypothesized that by optimizing scaffold composition and architecture, HA-collagen bone tissue engineering scaffolds could provide both an excellent biological response along with improved structural properties. The mechanical properties of freeze-dried HA-collagen scaffolds, the most common type of porous HA-collagen material, were first shown to be increased by the addition of HA reinforcements, but scaffold stiffness still fell far short of the desired range. Based on limitations inherent in the freeze-dried process, a new type of leached-porogen scaffold fabrication process was developed. Proof-of-concept scaffolds demonstrated the feasibility of producing leached-porogen HA-collagen materials, and the scaffold architecture was optimized though careful selection of porogen particle size and shape along with an improved crosslinking technique. The final scaffolds exhibited substantially increased compressive modulus compared to previous types HA-collagen scaffolds, while the porosity, pore size, and scaffold permeability were tailored to be suitable for bone tissue ingrowth. An in vitro study demonstrated the capacity of the leached-porogen scaffolds to serve as a substrate for the differentiation of osteoblasts and subsequent production of new bone tissue. The new leached-porogen scaffold HA-collagen scaffolds were

  6. Controlled mineralisation and recrystallisation of brushite within alginate hydrogels.

    PubMed

    Bjørnøy, Sindre H; Bassett, David C; Ucar, Seniz; Andreassen, Jens-Petter; Sikorski, Pawel

    2016-02-01

    Due to high solubility and fast resorption behaviour under physiological conditions, brushite (CaHPO4⋅2H2O, calcium monohydrogen phosphate dihydrate, dicalcium phosphate dihydrate) has great potential in bone regeneration applications, both in combination with scaffolds or as a component of calcium phosphate cements. The use of brushite in combination with hydrogels opens up possibilities for new cell-based tissue engineering applications of this promising material. However, published preparation methods of brushite composites, in which the mineral phase is precipitated within the hydrogel network, fail to offer the necessary degree of control over the mineral phase, content and distribution within the hydrogel matrix. The main focus of this study is to address these shortcomings by determining the precise fabrication parameters needed to prepare composites with controlled composition and properties. Composite alginate microbeads were prepared using a counter-diffusion technique, which allows for the simultaneous crosslinking of the hydrogel and precipitation of an inorganic mineral phase. Reliable nucleation of a desired mineral phase within the alginate network proved more challenging than simple aqueous precipitation. This was largely due to ion transport within the hydrogel producing concentration gradients that modified levels of supersaturation and favoured the nucleation of other phases such as hydroxyapatite and octacalcium phosphate, which would otherwise not form. To overcome this, the incorporation of brushite seed crystals resulted in good control during the mineral phase, and by adjusting the number of seeds and amount of precursor concentration, the amount of mineral could be tuned. The material was characterised with a range of physical techniques, including scanning electron microscopy, powder x-ray diffraction and Rietveld refinement, Fourier transform infrared spectroscopy, and thermogravimetric analysis, in order to assess the mineral

  7. Coaxial additive manufacture of biomaterial composite scaffolds for tissue engineering.

    PubMed

    Cornock, R; Beirne, S; Thompson, B; Wallace, G G

    2014-06-01

    An inherent difficulty associated with the application of suitable bioscaffolds for tissue engineering is the incorporation of adequate mechanical characteristics into the materials which recapitulate that of the native tissue, whilst maintaining cell proliferation and nutrient transfer qualities. Biomaterial composites fabricated using rapid prototyping techniques can potentially improve the functionality and patient-specific processing of tissue engineering scaffolds. In this work, a technique for the coaxial melt extrusion printing of core-shell scaffold structures was designed, implemented and assessed with respect to the repeatability, cell efficacy and scaffold porosity obtainable. Encapsulated alginate hydrogel/thermoplastic polycaprolactone (Alg-PCL) cofibre scaffolds were fabricated. Selective laser melting was used to produce a high resolution stainless steel 316 L coaxial extrusion nozzle, exhibiting diameters of 300 μm/900 μm for the inner and outer nozzles respectively. We present coaxial melt extrusion printed scaffolds of Alg-PCL cofibres with ~0.4 volume fraction alginate, with total fibre diameter as low as 600 μm and core material offset as low as 10% of the total diameter. Furthermore the tuneability of scaffold porosity, pore size and interconnectivity, as well as the preliminary inclusion, compatibility and survival of an L-929 mouse fibroblast cell-line within the scaffolds were explored. This preliminary cell work highlighted the need for optimal material selection and further design reiteration in future research. PMID:24658021

  8. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering. PMID:26700239

  9. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering.

  10. Scaffolding and Metacognition

    ERIC Educational Resources Information Center

    Holton, Derek; Clarke, David

    2006-01-01

    This paper proposes an expanded conception of scaffolding with four key elements: (1) scaffolding agency--expert, reciprocal, and self-scaffolding; (2) scaffolding domain--conceptual and heuristic scaffolding; (3) the identification of self-scaffolding with metacognition; and (4) the identification of six zones of scaffolding activity; each zone…

  11. The effect of calcium chloride concentration on alginate/Fmoc-diphenylalanine hydrogel networks.

    PubMed

    Çelik, Ekin; Bayram, Cem; Akçapınar, Rümeysa; Türk, Mustafa; Denkbaş, Emir Baki

    2016-09-01

    Peptide based hydrogels gained a vast interest in the tissue engineering studies thanks to great superiorities such as biocompatibility, supramolecular organization without any need of additional crosslinker, injectability and tunable nature. Fmoc-diphenylalanine (FmocFF) is one of the earliest and widely used example of these small molecule gelators that have been utilized in biomedical studies. However, Fmoc-peptides are not feasible for long term use due to low stability and weak mechanical properties at neutral pH. In this study, Fmoc-FF dipeptides were mechanically enhanced by incorporation of alginate, a biocompatible and absorbable polysaccharide. The binary hydrogel is obtained via molecular self-assembly of FmocFF dipeptide in alginate solution followed by ionic crosslinking of alginate moieties with varying concentrations of calcium chloride. Hydrogel characterization was evaluated in terms of morphology, viscoelastic moduli and diffusional phenomena and the structures were tested as 3D scaffolds for bovine chondrocytes. In vitro evaluation of scaffolds lasted up to 14days and cell viability, sulphated glycosaminoglycan (sGAG) levels, collagen type II synthesis were determined. Our results showed that alginate incorporation into FmocFF hydrogels leads to better mechanical properties and higher stability with good biocompatibility.

  12. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  13. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  14. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  15. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  16. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  17. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  18. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  19. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  20. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  1. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  2. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  3. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  4. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  5. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  6. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  7. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1011 Alginic acid. (a) Alginic acid is a colloidal, hydrophilic polysaccharide obtained from...

  8. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  9. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  10. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  11. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  12. 21 CFR 582.7133 - Ammonium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammonium alginate. 582.7133 Section 582.7133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Ammonium alginate. (a) Product. Ammonium alginate. (b) Conditions of use. This substance is...

  13. 21 CFR 582.7133 - Ammonium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ammonium alginate. 582.7133 Section 582.7133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Ammonium alginate. (a) Product. Ammonium alginate. (b) Conditions of use. This substance is...

  14. Nonlinear elasticity of alginate gels

    NASA Astrophysics Data System (ADS)

    Hashemnejad, Seyed Meysam; Kundu, Santanu

    Alginate is a naturally occurring anionic polysaccharide extracted from brown algae. Because of biocompatibility, low toxicity, and simple gelation process, alginate gels are used in biomedical and food applications. Here, we report the rheological behavior of ionically crosslinked alginate gels, which are obtained by in situ gelation of alginates with calcium salts, in between two parallel plates of a rheometer. Strain stiffening behavior was captured using large amplitude oscillatory shear (LAOS) experiments. In addition, negative normal stress was observed for these gels, which has not been reported earlier for any polysaccharide networks. The magnitude of negative normal stress increases with applied strain and can exceed that of the shear stress at large strain. Rheological results fitted with a constitutive model that considers both stretching and bending of chains indicate that nonlinearity is likely related to the stretching of the chains between the crosslink junctions. The results provide an improved understanding of the deformation mechanism of ionically crosslinked alginate gel and the results will be important in developing synthetic extracellular matrix (ECM) from these materials.

  15. Healing and Preventive Effects of Calcium Alginate on Carbon Tetrachloride Induced Liver Injury in Rats

    PubMed Central

    Khotimchenko, Yuri S.; Khotimchenko, Maxim Y.

    2004-01-01

    The purpose of this study was to investigate the pharmacological effects of calcium alginate on carbon tetrachloride (CCL4)-induced hepatotoxicity in rats. The study included two experiments. In the first experiment the animals were given daily CCL4 through gavage for 7 days and then 10, 50, or 250 mg/kg b.w. of calcium alginate for 21 days. The increased bilirubin level, enhanced alanine and aspartate aminotransferase activity in plasma and reduced liver glycogen content induced by CCL4 were partly normalized by alginate administration in a dose-dependent manner. In addition, alginate significantly improved CCL4-induced alterations of pro-oxidant and antioxidant biochemical parameters in liver and plasma compared to those of rats administered CCL4. In the second experiment the animals were given daily 10, 50 or 250 mg/kg b.w. of calcium alginate for 21 days before 7-day administration of CCL4. Pretreatment with alginate before CCL4 administration resulted in significantly inhibited increase of the blood enzymatic activities of alanine and aspartate aminotransferases and bilirubin level in a dose-dependent manner. Also, preliminary administration of alginate prevented elevation of lipid peroxidation products and reduction of liver glutathione content in rats given CCL4. These results suggest that calcium alginate exerts healing and preventive effects on CCL4-induced hepatotoxicity in rats.

  16. Superabsorbent nanocomposite (alginate-g-PAMPS/MMT): synthesis, characterization and swelling behavior.

    PubMed

    Yadav, Mithilesh; Rhee, Kyong Yop

    2012-09-01

    A superabsorbent composite (alginate-g-PAMPS/MMT) was prepared by graft copolymerization from alginate, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and Na+ montmorillonite (MMT) in an inert atmosphere. Effects of polymerization variables on water absorbency, including the content of Na+ montmorillonite, sodium alginate, N,N'-methylenebisacrylamide and AMPS, were studied. The introduced montmorillonite formed a loose and porous surface and improved the water absorbency of the alginate-g-PAMPS/MMT superabsorbent composite. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3) and anionic salt solutions (NaCl and Na2SO4) were also systematically investigated. The superabsorbent composite was further characterized using Fourier transform infrared spectroscopy (FTIR), rheology, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking alginate-g-PAMPS as a reference. PMID:24751026

  17. Multi-featured macroporous agarose-alginate cryogel: synthesis and characterization for bioengineering applications.

    PubMed

    Tripathi, Anuj; Kumar, Ashok

    2011-01-10

    In this study agarose-alginate scaffolds are synthesized using cryogelation technology in different formats like monolith, sheet, discs, and beads, and show amiable mechanical strength like soft tissue properties and high interconnected macroporous degradable architecture. In cell-material interactions, fibroblast (NIH-3T3) cells showed good adherence and proliferation on these scaffolds presenting its potential application in soft tissue engineering. The application of cryogel beads and monoliths was also examined by the efficient immobilization of bacterial cells (BL21) on these matrices revealing their use for recovery of product from continuous fermentation systems without cell leakage. These scaffolds also showed potential as a filter for repeated recovery of heavy metal binding, such as copper and nickel from the waste water. The cryogels prepared herein do have a number of unique features that make them an important class of soft materials for developing multi-featured scaffolds as a novel carrier for bioengineering applications.

  18. Multi-featured macroporous agarose-alginate cryogel: synthesis and characterization for bioengineering applications.

    PubMed

    Tripathi, Anuj; Kumar, Ashok

    2011-01-10

    In this study agarose-alginate scaffolds are synthesized using cryogelation technology in different formats like monolith, sheet, discs, and beads, and show amiable mechanical strength like soft tissue properties and high interconnected macroporous degradable architecture. In cell-material interactions, fibroblast (NIH-3T3) cells showed good adherence and proliferation on these scaffolds presenting its potential application in soft tissue engineering. The application of cryogel beads and monoliths was also examined by the efficient immobilization of bacterial cells (BL21) on these matrices revealing their use for recovery of product from continuous fermentation systems without cell leakage. These scaffolds also showed potential as a filter for repeated recovery of heavy metal binding, such as copper and nickel from the waste water. The cryogels prepared herein do have a number of unique features that make them an important class of soft materials for developing multi-featured scaffolds as a novel carrier for bioengineering applications. PMID:21077225

  19. Detoxification of Hg(II) from aqueous and enzyme media: Pristine vs. tailored calcium alginate hydrogels.

    PubMed

    Sarkar, Kangkana; Ansari, Zarina; Sen, Kamalika

    2016-10-01

    Calcium alginate (CA) hydrogels were tailored using phenolic compounds (PC) like, thymol, morin, catechin, hesperidin, during their preparation. The PC incorporated gels show modified surface features as indicated by scanning electron microscopic images (SEM). The rheological studies show that excepting the hesperidin incorporated gels all the other kinds including calcium alginate pristine have similar mechanical strength. The hesperidine incorporated CA gels had the maximum capacity to adsorb Hg. The Freundlich adsorption isotherms show higher values of adsorption capacity for all PC incorporated CA beads than the pristine CA (PCA). The hesperidin incorporated CA gels were found to show the best adsorption condition at neutral pH and an optimum contact time of 2.5h at 25°C. Considering the possibility of ingested Hg detoxification from human alimentary tract, the hesperidin and morin incorporated CA beads were further modified through incorporation of cod liver oil as the digestion time of fat in stomach is higher. In vitro uptake capacities of Hg in pepsin and pancreatin containing enzyme media were studied with hesperidin and morin incorporated beads and their corresponding fat incorporated beads also. In the pepsin medium, there was no uptake by hesperidin and fat-hesperidin incorporated beads, which is possibly due to the higher acidity of the medium. But in pancreatin medium Hg was taken up by both kinds of beads. Morin and morin-fat incorporated beads were efficient to uptake Hg from both the pepsin and pancreatin medium. The tailored CA beads may therefore serve as efficient scaffolds to rescue Hg ingested individuals. PMID:27208797

  20. Scaffolded biology.

    PubMed

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology. PMID:27287514

  1. Scaffolded biology.

    PubMed

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology.

  2. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes.

    PubMed

    Kim, Han-Sem; Song, Minsoo; Lee, Eun-Jung; Shin, Ueon Sang

    2015-06-01

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H3PO4/P2O5/Et3PO4 followed by acid-base reaction with Ca(OAc)2 to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for (1)H, and (31)P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2w/v%) with NaAlg solution (2w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO4 or CaCl2 were added externally. The gelation was completed within about 3-40min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤6.7kPa for compressive strength at break and about 8.4kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100-800μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering. PMID:25842118

  3. In vivo bioengineered ovarian tumors based on collagen, matrigel, alginate and agarose hydrogels: a comparative study.

    PubMed

    Zheng, Li; Hu, Xuefeng; Huang, Yuanjie; Xu, Guojie; Yang, Jinsong; Li, Li

    2015-01-29

    Scaffold-based tumor engineering is rapidly evolving the study of cancer progression. However, the effects of scaffolds and environment on tumor formation have seldom been investigated. In this study, four types of injectable hydrogels, namely, collagen type I, Matrigel, alginate and agarose gels, were loaded with human ovarian cancer SKOV3 cells and then injected into nude mice subcutaneously. The growth of the tumors in vitro was also investigated. After four weeks, the specimens were harvested and analyzed. We found that tumor formation by SKOV3 cells was best supported by collagen, followed by Matrigel, alginate, control (without scaffold) and agarose in vivo. The collagen I group exhibited a larger tumor volume with increased neovascularization and increased necrosis compared with the other materials. Further, increased MMP activity, upregulated expression of laminin and fibronectin and higher levels of HIF-1α and VEGF-A in the collagen group revealed that the engineered tumor is closer to human ovarian carcinoma. In order, collagen, Matrigel, alginate, control (without scaffold) and agarose exhibited decreases in tumor formation. All evidence indicated that the in vivo engineered tumor is scaffold-dependent. Bioactive hydrogels are superior to inert hydrogels at promoting tumor regeneration. In particular, biomimetic hydrogels are advantageous because they provide a microenvironment that mimics the ECM of natural tumors. On the other hand, typical features of cancer cells and the expression of genes related to cancer malignancy were far less similar to the natural tumor in vitro, which indicated the importance of culture environment in vivo. Superior to the in vitro culture, nude mice can be considered satisfactory in vivo 'bioreactors' for the screening of favorable cell vehicles for tumor engineering in vitro.

  4. Perfluorinated alginate for cellular encapsulation.

    PubMed

    Gattás-Asfura, Kerim M; Fraker, Christopher A; Stabler, Cherie L

    2012-08-01

    Molecules of pentadecafluorooctanoyl chloride (PFC) were grafted onto alginate (Alg) using a linear poly(ethylene glycol) linker and amide bonds. The resulting Alg-PFC material was characterized by proton nuclear magnetic resonance and infrared spectroscopies. The degree of PFC functionalization significantly influenced the physical and chemical properties of Alg-PFC, particularly when the resulting polymer was ionically crosslinked into hydrogels. Alg-PFC hydrogel beads fabricated via Ba(2+) crosslinking were found to match the permeability properties of control alginate beads, except upon swelling over time in culture media. When used to encapsulate MIN6 cells, a beta cell line, Alg-PFC beads demonstrated enhanced cell proliferation over alginate control beads. These results indicate that Alg-PFC hydrogels retain some of the PFC's biological-relevant benefits, such as enhancement of mass transport and bioinertness, to enhance cellular viability within alginate three-dimensional hydrogel environments. We envision these functionalized hydrogels to be particularly useful in the encapsulation of cells with a high metabolic demand, such as pancreatic islets.

  5. A preliminary investigation into the use of alginates for the lifting and enhancement of fingermarks in blood.

    PubMed

    Munro, Mhairi; Deacon, Paul; Farrugia, Kevin J

    2014-05-01

    Recent studies have reported the use of alginate in the lifting and subsequent enhancement of footwear marks in blood. A study was set up to assess the use of such a method in the treatment of fingermarks in blood on a variety of porous, non-porous and semi-porous surfaces. Other variables included ageing of the fingermarks in blood and the application of chemicals prior to or post-alginate lifting. All different variations were compared to direct chemical treatment of the substrate. The results demonstrated that alginate is not compatible with certain substrates (e.g. glass and tile). On substrates that were compatible with alginate (e.g. fabric and paper), the enhanced fingermarks on the alginate cast and the enhanced fingermarks on the post-alginate substrates appeared, overall, inferior compared to direct chemical enhancement without the use of alginate. A further variation using water-based protein stains directly mixed with the alginate appeared to provide enhancement directly on the substrate as well as simultaneous lifting and enhancing the fingermarks in blood on the alginate cast.

  6. Molecular insight into the role of the N-terminal extension in the maturation, substrate recognition, and catalysis of a bacterial alginate lyase from polysaccharide lyase family 18.

    PubMed

    Dong, Sheng; Wei, Tian-Di; Chen, Xiu-Lan; Li, Chun-Yang; Wang, Peng; Xie, Bin-Bin; Qin, Qi-Long; Zhang, Xi-Ying; Pang, Xiu-Hua; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2014-10-24

    Bacterial alginate lyases, which are members of several polysaccharide lyase (PL) families, have important biological roles and biotechnological applications. The mechanisms for maturation, substrate recognition, and catalysis of PL18 alginate lyases are still largely unknown. A PL18 alginate lyase, aly-SJ02, from Pseudoalteromonas sp. 0524 displays a β-jelly roll scaffold. Structural and biochemical analyses indicated that the N-terminal extension in the aly-SJ02 precursor may act as an intramolecular chaperone to mediate the correct folding of the catalytic domain. Molecular dynamics simulations and mutational assays suggested that the lid loops over the aly-SJ02 active center serve as a gate for substrate entry. Molecular docking and site-directed mutations revealed that certain conserved residues at the active center, especially those at subsites +1 and +2, are crucial for substrate recognition. Tyr(353) may function as both a catalytic base and acid. Based on our results, a model for the catalysis of aly-SJ02 in alginate depolymerization is proposed. Moreover, although bacterial alginate lyases from families PL5, 7, 15, and 18 adopt distinct scaffolds, they share the same conformation of catalytic residues, reflecting their convergent evolution. Our results provide the foremost insight into the mechanisms of maturation, substrate recognition, and catalysis of a PL18 alginate lyase.

  7. Meniscal scaffolds.

    PubMed

    Myers, Kevin R; Sgaglione, Nicholas A; Goodwillie, Andrew D

    2014-12-01

    There are two scaffold products designed for meniscal reconstruction or substitution of partial meniscal defects that are currently available in the Europe: the collagen meniscal implant (CMI; Ivy Sports Medicine, Gräfelfing, Germany) and the polymer scaffold (PS; Actifit, Orteq Bioengineering, London, United Kingdom). The CMI has demonstrated improved clinical outcomes compared with baseline in patients with chronic postmeniscectomy symptoms with follow-up ranging from 5 to more than 10 years. There are also several comparative studies that report improved clinical scores in patients with chronic medial meniscus symptoms treated with CMI versus repeat partial meniscectomy, and a lower reoperation rate. Recently, PS insertion was shown to result in improved clinical outcomes in patients with chronic postmeniscectomy symptoms of the medial or lateral meniscus at short-term follow-up. However, there is currently no medium- or long-term data available for the PS. The use of meniscal scaffolds in the acute setting has not been found to result in improved outcomes in most studies. The authors' surgical indications for meniscal scaffold implantation, preferred surgical technique, and postoperative rehabilitation protocol are described. PMID:25172967

  8. The scaffold tree: an efficient navigation in the scaffold universe.

    PubMed

    Ertl, Peter; Schuffenhauer, Ansgar; Renner, Steffen

    2011-01-01

    The Scaffold Tree algorithm (J Chem Inf Model 47:47-58, 2007) allows to organize large molecular data sets by arranging sets of molecules into a unique tree hierarchy based on their scaffolds, with scaffolds forming leaf nodes of such tree. The hierarchy is created by iterative removal of rings from more complex scaffolds using chemically meaningful set of rules, until a single, root ring is obtained. The classification is deterministic, data set independent, and scales linearly with the number of compounds included in the data set. In this review we summarize the basic principles of the Scaffold Tree methodology and review its applications, which appeared in recent medicinal chemistry literature, including the use of Scaffold Trees for visualization of large chemical data sets, compound clustering, and the identification of novel bioactive molecules. References to several computer programs, including also free tools available on the Internet, allowing to perform classification and visualization of molecules based on their scaffolds are also provided. PMID:20838972

  9. Preventative Effects of Sodium Alginate on Indomethacin-induced Small-intestinal Injury in Mice.

    PubMed

    Horibe, Sayo; Tanahashi, Toshihito; Kawauchi, Shoji; Mizuno, Shigeto; Rikitake, Yoshiyuki

    2016-01-01

    Recent advances in diagnostic technologies have revealed that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious mucosal injury in the upper and lower gastrointestinal tract (including the small intestine). A drug to treat NSAID-induced small-intestinal injury (SII) is lacking. Sodium alginate is a soluble dietary fiber extracted from brown seaweed and its solution has been used as a hemostatic agent to treat gastrointestinal bleeding due to gastric ulcers. Whether sodium alginate has therapeutic effects on NSAID-induced SII and its mechanism of action are not known. Here, we investigated if administration of two forms (high-molecular-weight (HMW) and low-molecular-weight (LMW)) of sodium alginate could ameliorate indomethacin-induced SII. Pretreatment with HMW sodium alginate or LMW sodium alginate before indomethacin administration improved ulceration and the resultant intestinal shortening was associated with reduced histological severity of mucosal injury and ameliorated mRNA expression of inflammation-related molecules in the small intestine. We found that mRNAs of secretory Muc2 and membrane-associated Muc1, Muc3 and Muc4 were expressed in the small intestine. mRNA expression of Muc1-4 was increased in indomethacin-induced SII, and these increases were prevented by sodium alginate. Thus, administration of sodium alginate could be a therapeutic approach to prevent indomethacin-induced SII. PMID:27647994

  10. Preventative Effects of Sodium Alginate on Indomethacin-induced Small-intestinal Injury in Mice

    PubMed Central

    Horibe, Sayo; Tanahashi, Toshihito; Kawauchi, Shoji; Mizuno, Shigeto; Rikitake, Yoshiyuki

    2016-01-01

    Recent advances in diagnostic technologies have revealed that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious mucosal injury in the upper and lower gastrointestinal tract (including the small intestine). A drug to treat NSAID-induced small-intestinal injury (SII) is lacking. Sodium alginate is a soluble dietary fiber extracted from brown seaweed and its solution has been used as a hemostatic agent to treat gastrointestinal bleeding due to gastric ulcers. Whether sodium alginate has therapeutic effects on NSAID-induced SII and its mechanism of action are not known. Here, we investigated if administration of two forms (high-molecular-weight (HMW) and low-molecular-weight (LMW)) of sodium alginate could ameliorate indomethacin-induced SII. Pretreatment with HMW sodium alginate or LMW sodium alginate before indomethacin administration improved ulceration and the resultant intestinal shortening was associated with reduced histological severity of mucosal injury and ameliorated mRNA expression of inflammation-related molecules in the small intestine. We found that mRNAs of secretory Muc2 and membrane-associated Muc1, Muc3 and Muc4 were expressed in the small intestine. mRNA expression of Muc1-4 was increased in indomethacin-induced SII, and these increases were prevented by sodium alginate. Thus, administration of sodium alginate could be a therapeutic approach to prevent indomethacin-induced SII. PMID:27647994

  11. Preventative Effects of Sodium Alginate on Indomethacin-induced Small-intestinal Injury in Mice.

    PubMed

    Horibe, Sayo; Tanahashi, Toshihito; Kawauchi, Shoji; Mizuno, Shigeto; Rikitake, Yoshiyuki

    2016-01-01

    Recent advances in diagnostic technologies have revealed that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious mucosal injury in the upper and lower gastrointestinal tract (including the small intestine). A drug to treat NSAID-induced small-intestinal injury (SII) is lacking. Sodium alginate is a soluble dietary fiber extracted from brown seaweed and its solution has been used as a hemostatic agent to treat gastrointestinal bleeding due to gastric ulcers. Whether sodium alginate has therapeutic effects on NSAID-induced SII and its mechanism of action are not known. Here, we investigated if administration of two forms (high-molecular-weight (HMW) and low-molecular-weight (LMW)) of sodium alginate could ameliorate indomethacin-induced SII. Pretreatment with HMW sodium alginate or LMW sodium alginate before indomethacin administration improved ulceration and the resultant intestinal shortening was associated with reduced histological severity of mucosal injury and ameliorated mRNA expression of inflammation-related molecules in the small intestine. We found that mRNAs of secretory Muc2 and membrane-associated Muc1, Muc3 and Muc4 were expressed in the small intestine. mRNA expression of Muc1-4 was increased in indomethacin-induced SII, and these increases were prevented by sodium alginate. Thus, administration of sodium alginate could be a therapeutic approach to prevent indomethacin-induced SII.

  12. Preventative Effects of Sodium Alginate on Indomethacin-induced Small-intestinal Injury in Mice

    PubMed Central

    Horibe, Sayo; Tanahashi, Toshihito; Kawauchi, Shoji; Mizuno, Shigeto; Rikitake, Yoshiyuki

    2016-01-01

    Recent advances in diagnostic technologies have revealed that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious mucosal injury in the upper and lower gastrointestinal tract (including the small intestine). A drug to treat NSAID-induced small-intestinal injury (SII) is lacking. Sodium alginate is a soluble dietary fiber extracted from brown seaweed and its solution has been used as a hemostatic agent to treat gastrointestinal bleeding due to gastric ulcers. Whether sodium alginate has therapeutic effects on NSAID-induced SII and its mechanism of action are not known. Here, we investigated if administration of two forms (high-molecular-weight (HMW) and low-molecular-weight (LMW)) of sodium alginate could ameliorate indomethacin-induced SII. Pretreatment with HMW sodium alginate or LMW sodium alginate before indomethacin administration improved ulceration and the resultant intestinal shortening was associated with reduced histological severity of mucosal injury and ameliorated mRNA expression of inflammation-related molecules in the small intestine. We found that mRNAs of secretory Muc2 and membrane-associated Muc1, Muc3 and Muc4 were expressed in the small intestine. mRNA expression of Muc1-4 was increased in indomethacin-induced SII, and these increases were prevented by sodium alginate. Thus, administration of sodium alginate could be a therapeutic approach to prevent indomethacin-induced SII.

  13. Biomimetic Scaffold with Aligned Microporosity Designed for Dentin Regeneration

    PubMed Central

    Panseri, Silvia; Montesi, Monica; Dozio, Samuele Maria; Savini, Elisa; Tampieri, Anna; Sandri, Monica

    2016-01-01

    Tooth loss is a common result of a variety of oral diseases due to physiological causes, trauma, genetic disorders, and aging and can lead to physical and mental suffering that markedly lowers the individual’s quality of life. Tooth is a complex organ that is composed of mineralized tissues and soft connective tissues. Dentin is the most voluminous tissue of the tooth and its formation (dentinogenesis) is a highly regulated process displaying several similarities with osteogenesis. In this study, gelatin, thermally denatured collagen, was used as a promising low-cost material to develop scaffolds for hard tissue engineering. We synthetized dentin-like scaffolds using gelatin biomineralized with magnesium-doped hydroxyapatite and blended it with alginate. With a controlled freeze-drying process and alginate cross-linking, it is possible to obtain scaffolds with microscopic aligned channels suitable for tissue engineering. 3D cell culture with mesenchymal stem cells showed the promising properties of the new scaffolds for tooth regeneration. In detail, the chemical–physical features of the scaffolds, mimicking those of natural tissue, facilitate the cell adhesion, and the porosity is suitable for long-term cell colonization and fine cell–material interactions. PMID:27376060

  14. Biomimetic Scaffold with Aligned Microporosity Designed for Dentin Regeneration.

    PubMed

    Panseri, Silvia; Montesi, Monica; Dozio, Samuele Maria; Savini, Elisa; Tampieri, Anna; Sandri, Monica

    2016-01-01

    Tooth loss is a common result of a variety of oral diseases due to physiological causes, trauma, genetic disorders, and aging and can lead to physical and mental suffering that markedly lowers the individual's quality of life. Tooth is a complex organ that is composed of mineralized tissues and soft connective tissues. Dentin is the most voluminous tissue of the tooth and its formation (dentinogenesis) is a highly regulated process displaying several similarities with osteogenesis. In this study, gelatin, thermally denatured collagen, was used as a promising low-cost material to develop scaffolds for hard tissue engineering. We synthetized dentin-like scaffolds using gelatin biomineralized with magnesium-doped hydroxyapatite and blended it with alginate. With a controlled freeze-drying process and alginate cross-linking, it is possible to obtain scaffolds with microscopic aligned channels suitable for tissue engineering. 3D cell culture with mesenchymal stem cells showed the promising properties of the new scaffolds for tooth regeneration. In detail, the chemical-physical features of the scaffolds, mimicking those of natural tissue, facilitate the cell adhesion, and the porosity is suitable for long-term cell colonization and fine cell-material interactions. PMID:27376060

  15. 3D printing facilitated scaffold-free tissue unit fabrication.

    PubMed

    Tan, Yu; Richards, Dylan J; Trusk, Thomas C; Visconti, Richard P; Yost, Michael J; Kindy, Mark S; Drake, Christopher J; Argraves, William Scott; Markwald, Roger R; Mei, Ying

    2014-06-01

    Tissue spheroids hold great potential in tissue engineering as building blocks to assemble into functional tissues. To date, agarose molds have been extensively used to facilitate fusion process of tissue spheroids. As a molding material, agarose typically requires low temperature plates for gelation and/or heated dispenser units. Here, we proposed and developed an alginate-based, direct 3D mold-printing technology: 3D printing microdroplets of alginate solution into biocompatible, bio-inert alginate hydrogel molds for the fabrication of scaffold-free tissue engineering constructs. Specifically, we developed a 3D printing technology to deposit microdroplets of alginate solution on calcium containing substrates in a layer-by-layer fashion to prepare ring-shaped 3D hydrogel molds. Tissue spheroids composed of 50% endothelial cells and 50% smooth muscle cells were robotically placed into the 3D printed alginate molds using a 3D printer, and were found to rapidly fuse into toroid-shaped tissue units. Histological and immunofluorescence analysis indicated that the cells secreted collagen type I playing a critical role in promoting cell-cell adhesion, tissue formation and maturation.

  16. 3D Printing Facilitated Scaffold-free Tissue Unit Fabrication

    PubMed Central

    Tan, Yu; Richards, Dylan J.; Trusk, Thomas C.; Visconti, Richard P.; Yost, Michael J.; Kindy, Mark S.; Drake, Christopher J.; Argraves, William Scott; Markwald, Roger R.; Mei, Ying

    2014-01-01

    Tissue spheroids hold great potential in tissue engineering as building blocks to assemble into functional tissues. To date, agarose molds have been extensively used to facilitate fusion process of tissue spheroids. As a molding material, agarose typically requires low temperature plates for gelation and/or heated dispenser units. Here, we proposed and developed an alginate-based, direct 3D mold-printing technology: 3D printing micro-droplets of alginate solution into biocompatible, bio-inert alginate hydrogel molds for the fabrication of scaffold-free tissue engineering constructs. Specifically, we developed a 3D printing technology to deposit micro-droplets of alginate solution on calcium containing substrates in a layer-by-layer fashion to prepare ring-shaped 3D hydrogel molds. Tissue spheroids composed of 50% endothelial cells and 50% smooth muscle cells were robotically placed into the 3D printed alginate molds using a 3D printer, and were found to rapidly fuse into toroid-shaped tissue units. Histological and immunofluorescence analysis indicated that the cells secreted collagen type I playing a critical role in promoting cell-cell adhesion, tissue formation and maturation. PMID:24717646

  17. Effect of Alginate Concentration on Alginate-TiO2 Hydrogel for Lead Ion Removal

    NASA Astrophysics Data System (ADS)

    Teoh, W. T.; Saito, N.; Sato, K.

    2011-03-01

    Alginate-TiO2 hydrogel was investigated for lead ion (Pb(II)) removal. By immobilizing TiO2 powder onto an alginate biopolymer, it is possible to utilize the ion exchange properties of the alginate and the photoreducibility of TiO2 to recover Pb(II). However, these photocatalytic activities degrade the alginate biopolymer in addition to removing Pb(II). This study examines photolytic degradation of alginate-TiO2 hydrogels prepared with alginate concentrations of 1, 1.5, 2, and 2.5%w/v; the same amount (0.4%w/v) of TiO2 was added to each alginate solution. The alginate-TiO2 hydrogels were formed by dripping the alginate-TiO2 suspension into a 0.2 M calcium chloride solution. The samples were washed and dried and then photoirradiated. The samples with alginate concentrations of 1 and 1.5%w/v were depolymerized, whereas the surface morphology of the sample that prepared from the 2%w/v alginate solution remained unchanged. The samples prepared from 1.5, 2, and 2.5%w/v alginate solutions had Pb(II) uptakes of 24.0, 39.8, and 39.7 mg/g, respectively.

  18. Improved cell infiltration of highly porous nanofibrous scaffolds formed by combined fiber-fiber charge repulsions and ultra-sonication

    PubMed Central

    Jeong, Sung Isn; Burns, Nancy A.; Bonino, Christopher A.; Kwon, Il Keun; Khan, Saad A.; Alsberg, Eben

    2014-01-01

    A significant problem affecting electrospun nanofibrous tissue scaffolds is poor infiltration of cells into their three-dimensional (3D) structure. Environmental and physical manipulation, however, can enhance cellular infiltration into electrospun scaffolds. In this work, RGD-modified alginate mats with increased thickness and porosity were achieved by pairing high humidity electrospinning with post-processing ultra-sonication. RGD-modified alginate, polyethylene oxide (PEO), and an FDA-approved, nonionic surfactant blends were electrospun in 20 and 50% relative humidity conditions. Mats electrospun in high humidity conditions resulted in significantly increased mat thickness and decreased fiber diameters. The mats’ alginate content was then isolated via ionic crosslinking and PEO/surfactant extraction. Finally, the alginate-only mat was post-processed by ultra-sonication to further enhance its cross-sectional thickness. Cell morphology, proliferation, and infiltration into the scaffolds were evaluated by seeding fibroblasts onto the alginate mat. Cell spreading, growth and infiltration improved with increased humidity and ultra-sonication. This approach shows great promise for the design of cell-permeable nanofibrous scaffolds for tissue-engineering applications. PMID:25530854

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

    PubMed

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

    2015-01-01

    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. PMID:26689257

  20. 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.

  1. Engineering alginate as bioink for bioprinting.

    PubMed

    Jia, Jia; Richards, Dylan J; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P; Trusk, Thomas C; Yost, Michael J; Yao, Hai; Markwald, Roger R; Mei, Ying

    2014-10-01

    Recent advances in three-dimensional (3-D) printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been used extensively as bioinks for 3-D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations was prepared to develop a bioink platform that can be applied to a multitude of tissue engineering applications. The authors systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting the structure integrity of the lattice structures (except the highly degradable one) after 8days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  2. Engineering alginate as bioink for bioprinting

    PubMed Central

    Jia, Jia; Richards, Dylan J.; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P.; Trusk, Thomas C.; Yost, Michael J.; Yao, Hai; Markwald, Roger R.; Mei, Ying

    2015-01-01

    Recent advances in 3D printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been extensively utilized as bioinks for 3D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, we prepared a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations to develop a bioink platform that can be applied to a multitude of tissue engineering applications. We systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting structure integrity of the lattice structures (except the highly degradable one) after 8 days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  3. A compressible scaffold for minimally invasive delivery of large intact neuronal networks.

    PubMed

    Béduer, Amélie; Braschler, Thomas; Peric, Oliver; Fantner, Georg E; Mosser, Sébastien; Fraering, Patrick C; Benchérif, Sidi; Mooney, David J; Renaud, Philippe

    2015-01-28

    Millimeter to centimeter-sized injectable neural scaffolds based on macroporous cryogels are presented. The polymer-scaffolds are made from alginate and carboxymethyl-cellulose by a novel simple one-pot cryosynthesis. They allow surgical sterility by means of autoclaving, and present native laminin as an attachment motive for neural adhesion and neurite development. They are designed to protect an extended, living neuronal network during compression to a small fraction of the original volume in order to enable minimally invasive delivery. The scaffolds behave as a mechanical meta-material: they are soft at the macroscopic scale, enabling injection through narrow-bore tubing and potentially good cellular scaffold integration in soft target tissues such as the brain. At the same time, the scaffold material has a high local Young modulus, allowing protection of the neuronal network during injection. Based on macroscopic and nanomechanical characterization, the generic geometrical and mechanical design rules are presented, enabling macroporous cellular scaffold injectability.

  4. Alginate cryogel based glucose biosensor

    NASA Astrophysics Data System (ADS)

    Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

    2016-02-01

    Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

  5. Physicochemical characterization and biocompatibility of alginate-polycation microcapsules designed for islet transplantation

    NASA Astrophysics Data System (ADS)

    Tam, Susan Kimberly

    diabetic mice. To achieve these aims, extensive physicochemical analyses of the alginates and microcapsules were carried out. Among the properties of the alginates that were investigated include their purity (LAL assay, microBCA), chemical composition (nuclear magnetic resonance, NMR), elemental composition (x-ray photoelectron spectroscopy, XPS), and hydrophilicity (contact angle technique). As for the microcapsules, we also examined their surface chemical composition (XPS), hydrophilicity, as well as alginate-polycation interactions (Fourier transform infrared spectroscopy, FTIR), and membrane strength (osmotic swelling). The results of this research led to a number of important conclusions about the biocompatibility of alginates and alginate-based microcapsules. First of all, purifying an alginate does not guarantee its biocompatibility. Indeed, we provided evidence that both the alginate chemical composition (i.e. relative content of mannuronate and guluronate) and its intrinsic viscosity influence the extent of host cell adhesion to alginate gel beads. Using a biocompatible alginate, we then provided evidence that microcapsule biocompatibility is greatly compromised by its polycationic membrane. We showed that this membrane is responsible for the adsorption of opsonizing proteins in vitro and the adhesion of immune cells in vivo. That said, the severity of inflammatory response to the membrane can vary, and this depended on the microcapsule design, including the choice of alginate and polycation type. Results of our physicochemical analyses suggested that the most important factor determining biocompatibility is the ability of the polycation to diffuse into, and subsequently bind to, the alginate gel core. Moreover, adding a final coating of alginate had no significant effect on reversing the effects of the membrane on various microcapsule properties (surface composition, hydrophobicity, stability), nor did this coating reduce its immunogenicity. Although we

  6. Alginate/Poly(γ-glutamic Acid) Base Biocompatible Gel for Bone Tissue Engineering

    PubMed Central

    Chan, Wing P.; Kung, Fu-Chen; Kuo, Yu-Lin; Yang, Ming-Chen; Lai, Wen-Fu Thomas

    2015-01-01

    A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid), alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca2+ from Ca–γ-PGA directly and γ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and for γ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials. PMID:26504784

  7. Effects of Chitin Whiskers on Physical Properties and Osteoblast Culture of Alginate Based Nanocomposite Hydrogels.

    PubMed

    Huang, Yao; Yao, Mengyu; Zheng, Xing; Liang, Xichao; Su, Xiaojuan; Zhang, Yu; Lu, Ang; Zhang, Lina

    2015-11-01

    Novel nanocomposite hydrogels composed of polyelectrolytes alginate and chitin whiskers with biocompatibility were successfully fabricated based on the pH-induced charge shifting behavior of chitin whiskers. The chitin whiskers with mean length and width of 300 and 20 nm were uniformly dispersed in negatively charged sodium alginate aqueous solution, leading to the formation of the homogeneous nanocomposite hydrogels. The experimental results indicated that their mechanical properties were significantly improved compared to alginate hydrogel and the swelling trends were inhibited as a result of the strong electrostatic interactions between the chitin whiskers and alginate. The nanocomposite hydrogels exhibited certain crystallinity and hierarchical structure with nanoscale chitin whiskers, similar to the structure of the native extracellular matrix. Moreover, the nanocomposite hydrogels were successfully applied as bone scaffolds for MC3T3-E1 osteoblast cells, showing their excellent biocompatibility and low cytotoxicity. The results of fluorescent micrographs and scanning electronic microscope (SEM) images revealed that the addition of chitin whiskers into the nanocomposite hydrogels markedly promoted the cell adhesion and proliferation of the osteoblast cells. The biocompatible nanocomposite hydrogels have potential application in bone tissue engineering. PMID:26393272

  8. Effects of Chitin Whiskers on Physical Properties and Osteoblast Culture of Alginate Based Nanocomposite Hydrogels.

    PubMed

    Huang, Yao; Yao, Mengyu; Zheng, Xing; Liang, Xichao; Su, Xiaojuan; Zhang, Yu; Lu, Ang; Zhang, Lina

    2015-11-01

    Novel nanocomposite hydrogels composed of polyelectrolytes alginate and chitin whiskers with biocompatibility were successfully fabricated based on the pH-induced charge shifting behavior of chitin whiskers. The chitin whiskers with mean length and width of 300 and 20 nm were uniformly dispersed in negatively charged sodium alginate aqueous solution, leading to the formation of the homogeneous nanocomposite hydrogels. The experimental results indicated that their mechanical properties were significantly improved compared to alginate hydrogel and the swelling trends were inhibited as a result of the strong electrostatic interactions between the chitin whiskers and alginate. The nanocomposite hydrogels exhibited certain crystallinity and hierarchical structure with nanoscale chitin whiskers, similar to the structure of the native extracellular matrix. Moreover, the nanocomposite hydrogels were successfully applied as bone scaffolds for MC3T3-E1 osteoblast cells, showing their excellent biocompatibility and low cytotoxicity. The results of fluorescent micrographs and scanning electronic microscope (SEM) images revealed that the addition of chitin whiskers into the nanocomposite hydrogels markedly promoted the cell adhesion and proliferation of the osteoblast cells. The biocompatible nanocomposite hydrogels have potential application in bone tissue engineering.

  9. Alginate/Poly(γ-glutamic Acid) Base Biocompatible Gel for Bone Tissue Engineering.

    PubMed

    Chan, Wing P; Kung, Fu-Chen; Kuo, Yu-Lin; Yang, Ming-Chen; Lai, Wen-Fu Thomas

    2015-01-01

    A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid), alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca(2+) from Ca-γ-PGA directly and γ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and for γ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials. PMID:26504784

  10. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level

    PubMed Central

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein

    2015-01-01

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface. PMID:26655760

  11. Multilayered Short Peptide-Alginate Blends as New Materials for Potential Applications in Cartilage Tissue Regeneration.

    PubMed

    Knoll, Grant A; Romanelli, Steven M; Brown, Alexandra M; Sortino, Rachel M; Banerjee, Ipsita A

    2016-03-01

    Peptide based nanomaterials have been gaining increased prominence due to their ability to form permeable scaffolds that promote growth and regeneration of new tissue. In this work for the first time a short hexapeptide motif VQIVYK, derived from the Tau protein family was conjugated with an organic polyamine linker, putrescine and utilized as a template for developing new materials for cartilage tissue regeneration. Our results showed that the conjugate formed extensive nanofibrous assemblies upon self-assembly under aqueous conditions. We then employed the layer-by-layer (LBL) approach to design the scaffold by first incorporating a short segment of the dentin sialophosphoprotein motif GDASYNSDESK followed by integration with the peptide sequence GSGAGAGSGAGAGSGAGA. This sequence mimics Ala, Gly, Ser repeats seen in the spider silk protein. We then incorporated the polysaccharide alginate which served as a hydrogel. To further enhance binding interactions with chondrocytes, and promote the formation of cartilage in vitro, the bionanocomposites were then attached to the chondrocyte binding peptide sequence HDSQLEALIKFM. The thermal properties as well as biodegradability of the scaffold was examined. To confirm biocompatibility, we examined cell viability, attachment and morphology in the presence of bovine chondrocytes. The cells were found to efficiently adhere to the scaffolds which formed an intricate mesh mimicking the extracellular matrix of cartilage tissue. To evaluate if differentiation occurred in the presence of the scaffolds, we examined in vitro deposition of proteoglycans. Thus, we have developed a new family of nanoscale scaffolds that may be utilized for cartilage tissue regeneration.

  12. Multilayered Short Peptide-Alginate Blends as New Materials for Potential Applications in Cartilage Tissue Regeneration.

    PubMed

    Knoll, Grant A; Romanelli, Steven M; Brown, Alexandra M; Sortino, Rachel M; Banerjee, Ipsita A

    2016-03-01

    Peptide based nanomaterials have been gaining increased prominence due to their ability to form permeable scaffolds that promote growth and regeneration of new tissue. In this work for the first time a short hexapeptide motif VQIVYK, derived from the Tau protein family was conjugated with an organic polyamine linker, putrescine and utilized as a template for developing new materials for cartilage tissue regeneration. Our results showed that the conjugate formed extensive nanofibrous assemblies upon self-assembly under aqueous conditions. We then employed the layer-by-layer (LBL) approach to design the scaffold by first incorporating a short segment of the dentin sialophosphoprotein motif GDASYNSDESK followed by integration with the peptide sequence GSGAGAGSGAGAGSGAGA. This sequence mimics Ala, Gly, Ser repeats seen in the spider silk protein. We then incorporated the polysaccharide alginate which served as a hydrogel. To further enhance binding interactions with chondrocytes, and promote the formation of cartilage in vitro, the bionanocomposites were then attached to the chondrocyte binding peptide sequence HDSQLEALIKFM. The thermal properties as well as biodegradability of the scaffold was examined. To confirm biocompatibility, we examined cell viability, attachment and morphology in the presence of bovine chondrocytes. The cells were found to efficiently adhere to the scaffolds which formed an intricate mesh mimicking the extracellular matrix of cartilage tissue. To evaluate if differentiation occurred in the presence of the scaffolds, we examined in vitro deposition of proteoglycans. Thus, we have developed a new family of nanoscale scaffolds that may be utilized for cartilage tissue regeneration. PMID:27455656

  13. Electrospun multifunctional tissue engineering scaffolds

    NASA Astrophysics Data System (ADS)

    Wang, Chong; Wang, Min

    2014-03-01

    Tissue engineering holds great promises in providing successful treatments of human body tissue loss that current methods are unable to treat or unable to achieve satisfactory clinical outcomes. In scaffold-based tissue engineering, a highperformance scaffold underpins the success of a tissue engineering strategy and a major direction in the field is to create multifunctional tissue engineering scaffolds for enhanced biological performance and for regenerating complex body tissues. Electrospinning can produce nanofibrous scaffolds that are highly desirable for tissue engineering. The enormous interest in electrospinning and electrospun fibrous structures by the science, engineering and medical communities has led to various developments of the electrospinning technology and wide investigations of electrospun products in many industries, including biomedical engineering, over the past two decades. It is now possible to create novel, multicomponent tissue engineering scaffolds with multiple functions. This article provides a concise review of recent advances in the R & D of electrospun multifunctional tissue engineering scaffolds. It also presents our philosophy and research in the designing and fabrication of electrospun multicomponent scaffolds with multiple functions.

  14. Development of an angiogenesis-promoting microvesicle-alginate-polycaprolactone composite graft for bone tissue engineering applications

    PubMed Central

    Zhang, Liming; Lei, Qian; Zhao, Aiqi; Wang, Hongxiang; Li, Qiubai

    2016-01-01

    One of the major challenges of bone tissue engineering applications is to construct a fully vascularized implant that can adapt to hypoxic environments in vivo. The incorporation of proangiogenic factors into scaffolds is a widely accepted method of achieving this goal. Recently, the proangiogenic potential of mesenchymal stem cell-derived microvesicles (MSC-MVs) has been confirmed in several studies. In the present study, we incorporated MSC-MVs into alginate-polycaprolactone (PCL) constructs that had previously been developed for bone tissue engineering applications, with the aim of promoting angiogenesis and bone regeneration. MSC-MVs were first isolated from the supernatant of rat bone marrow-derived MSCs and characterized by scanning electron microscopic, confocal microscopic, and flow cytometric analyses. The proangiogenic potential of MSC-MVs was demonstrated by the stimulation of tube formation of human umbilical vein endothelial cells in vitro. MSC-MVs and osteodifferentiated MSCs were then encapsulated with alginate and seeded onto porous three-dimensional printed PCL scaffolds. When combined with osteodifferentiated MSCs, the MV-alginate-PCL constructs enhanced vessel formation and tissue-engineered bone regeneration in a nude mouse subcutaneous bone formation model, as demonstrated by micro-computed tomographic, histological, and immunohistochemical analyses. This MV-alginate-PCL construct may offer a novel, proangiogenic, and cost-effective option for bone tissue engineering. PMID:27231660

  15. Alginate lyase: Review of major sources and classification, properties, structure-function analysis and applications

    PubMed Central

    Zhu, Benwei; Yin, Heng

    2015-01-01

    Alginate lyases catalyze the degradation of alginate, a complex copolymer of α-L-guluronate and its C5 epimer β-D-mannuronate. The enzymes have been isolated from various kinds of organisms with different substrate specificities, including algae, marine mollusks, marine and terrestrial bacteria, and some viruses and fungi. With the progress of structural biology, many kinds of alginate lyases of different polysaccharide lyases families have been characterized by obtaining crystal structures, and the catalytic mechanism has also been elucidated. Combined with various studies, we summarized the source, classification and properties of the alginate lyases from different polysaccharide lyases families. The relationship between substrate specificity and protein sequence was also investigated. PMID:25831216

  16. Preparation of calcium alginate microgel beads in an electrodispersion reactor using an internal source of calcium carbonate nanoparticles.

    PubMed

    Zhao, Yinyan; Carvajal, M Teresa; Won, You-Yeon; Harris, Michael T

    2007-12-01

    An electrodispersion reactor has been used to prepare calcium alginate (Ca-alginate) microgel beads in this study. In the electrodispersion reactor, pulsed electric fields are utilized to atomize aqueous mixtures of sodium alginate and CaCO3 nanoparticles (dispersed phase) from a nozzle into an immiscible, insulating second liquid (continuous phase) containing a soluble organic acid. This technique combines the features of the electrohydrodynamic force driven emulsion processes and externally triggered gelations in microreactors (the droplets) ultimately to yield soft gel beads. The average particle size of the Ca-alginate gels generated by this method changed from 412 +/- 90 to 10 +/- 3 microm as the applied peak voltage was increased. A diagram depicting structural information for the Ca-alginate was constructed as a function of the concentrations of sodium alginate and CaCO3 nanoparticles. From this diagram, a critical concentration of sodium alginate required for sol-gel transformation was observed. The characteristic highly porous structure of Ca-alginate particles made by this technique appears suitable for microencapsulation applications. Finally, time scale analysis was performed for the electrodispersion processes that include reactions in the microreactor droplets to provide guidelines for the future employment of this technique. This electrodispersion reactor can be used potentially in the formation of many reaction-based microencapsulation systems.

  17. Alginate as a protease inhibitor in vitro and in a model gut system; selective inhibition of pepsin but not trypsin

    PubMed Central

    Chater, Peter Ian; Wilcox, Mathew D.; Brownlee, Iain A.; Pearson, Jeffrey P.

    2015-01-01

    Alginates are widely used in the food and medical industries, including as a Gastro-Oesophagul Reflux treatment. This work investigates the inhibitory effects of alginate on the reflux aggressors trypsin and pepsin and the role of alginate-substrate binding, pH and alginate structure on inhibition. Alginates were shown to reduce pepsin activity by up to 53.9% (±9.5SD) in vitro. Strong positive correlation between alginate mannuronate residue frequency and levels of pepsin inhibition was observed. Limited inhibition of trypsin was shown. Viscometric observations of pH dependent interactions between alginate and protein suggest a mechanism whereby pH dependent ionic interactions reduce substrate availability to enzyme at acidic pH. To understand how dietary protein digestion is affected by alginate, proteolytic digestion was investigated in an in vitro model of the upper digestive tract. Significant inhibition of proteolysis was shown in the gastric phase of digestion, but not the small intestinal phase. PMID:26256170

  18. Evaluation of polyelectrolyte complex-based scaffolds for mesenchymal stem cell therapy in cardiac ischemia treatment.

    PubMed

    Ceccaldi, Caroline; Bushkalova, Raya; Alfarano, Chiara; Lairez, Olivier; Calise, Denis; Bourin, Philippe; Frugier, Celine; Rouzaud-Laborde, Charlotte; Cussac, Daniel; Parini, Angelo; Sallerin, Brigitte; Fullana, Sophie Girod

    2014-02-01

    Three-dimensional (3D) scaffolds hold great potential for stem cell-based therapies. Indeed, recent results have shown that biomimetic scaffolds may enhance cell survival and promote an increase in the concentration of therapeutic cells at the injury site. The aim of this work was to engineer an original polymeric scaffold based on the respective beneficial effects of alginate and chitosan. Formulations were made from various alginate/chitosan ratios to form opposite-charge polyelectrolyte complexes (PECs). After freeze-drying, the resultant matrices presented a highly interconnected porous microstructure and mechanical properties suitable for cell culture. In vitro evaluation demonstrated their compatibility with mesenchymal stell cell (MSC) proliferation and their ability to maintain paracrine activity. Finally, the in vivo performance of seeded 3D PEC scaffolds with a polymeric ratio of 40/60 was evaluated after an acute myocardial infarction provoked in a rat model. Evaluation of cardiac function showed a significant increase in the ejection fraction, improved neovascularization, attenuated fibrosis as well as less left ventricular dilatation as compared to an animal control group. These results provide evidence that 3D PEC scaffolds prepared from alginate and chitosan offer an efficient environment for 3D culturing of MSCs and represent an innovative solution for tissue engineering.

  19. Preclinical evaluation of collagen type I scaffolds, including gelatin-collagen microparticles and loaded with a hydroglycolic Calendula officinalis extract in a lagomorph model of full-thickness skin wound.

    PubMed

    Millán, D; Jiménez, R A; Nieto, L E; Linero, I; Laverde, M; Fontanilla, M R

    2016-02-01

    Previously, we have developed collagen type I scaffolds including microparticles of gelatin-collagen type I (SGC) that are able to control the release of a hydroglycolic extract of the Calendula officinalis flower. The main goal of the present work was to carry out the preclinical evaluation of SGC alone or loaded with the C. officinalis extract (SGC-E) in a lagomorph model of full-thickness skin wound. A total of 39 rabbits were distributed in three groups, of 13 animals each. The first group was used to compare wound healing by secondary intention (control) with wound healing observed when wounds were grafted with SGC alone. Comparison of control wounds with wounds grafted with SGC-E was performed in the second group, and comparison of wounds grafted with SGC with wounds grafted with SGC-E was performed in the third group. Clinical follow-ups were carried in all animals after surgery, and histological and histomorphometric analyses were performed on tissues taken from the healed area and healthy surrounding tissue. Histological and histomorphometric results indicate that grafting of SGC alone favors wound healing and brings a better clinical outcome than grafting SGC-E. In vitro collagenase digestion data suggested that the association of the C. officinalis extract to SGC increased the SGC-E cross-linking, making it difficult to degrade and affecting its biocompatibility.

  20. Preclinical evaluation of collagen type I scaffolds, including gelatin-collagen microparticles and loaded with a hydroglycolic Calendula officinalis extract in a lagomorph model of full-thickness skin wound.

    PubMed

    Millán, D; Jiménez, R A; Nieto, L E; Linero, I; Laverde, M; Fontanilla, M R

    2016-02-01

    Previously, we have developed collagen type I scaffolds including microparticles of gelatin-collagen type I (SGC) that are able to control the release of a hydroglycolic extract of the Calendula officinalis flower. The main goal of the present work was to carry out the preclinical evaluation of SGC alone or loaded with the C. officinalis extract (SGC-E) in a lagomorph model of full-thickness skin wound. A total of 39 rabbits were distributed in three groups, of 13 animals each. The first group was used to compare wound healing by secondary intention (control) with wound healing observed when wounds were grafted with SGC alone. Comparison of control wounds with wounds grafted with SGC-E was performed in the second group, and comparison of wounds grafted with SGC with wounds grafted with SGC-E was performed in the third group. Clinical follow-ups were carried in all animals after surgery, and histological and histomorphometric analyses were performed on tissues taken from the healed area and healthy surrounding tissue. Histological and histomorphometric results indicate that grafting of SGC alone favors wound healing and brings a better clinical outcome than grafting SGC-E. In vitro collagenase digestion data suggested that the association of the C. officinalis extract to SGC increased the SGC-E cross-linking, making it difficult to degrade and affecting its biocompatibility. PMID:26597789

  1. Mechanical properties of C-5 epimerized alginates.

    PubMed

    Mørch, Y A; Holtan, S; Donati, I; Strand, B L; Skjåk-Braek, G

    2008-09-01

    There is an increased need for alginate materials with both enhanced and controllable mechanical properties in the fields of food, pharmaceutical and specialty applications. In the present work, well-characterized algal polymers and mannuronan were enzymatically modified using C-5 epimerases converting mannuronic acid residues to guluronic acid in the polymer chain. Composition and sequential structure of controls and epimerized alginates were analyzed by (1)H NMR spectroscopy. Mechanical properties of Ca-alginate gels were further examined giving Young's modulus, syneresis, rupture strength, and elasticity of the gels. Both mechanical strength and elasticity of hydrogels could be improved and manipulated by epimerization. In particular, alternating sequences were found to play an important role for the final mechanical properties of alginate gels, and interestingly, a pure polyalternating sample resulted in gels with extremely high syneresis and rupture strength. In conclusion, enzymatic modification was shown to be a valuable tool in modifying the mechanical properties of alginates in a highly specific manner.

  2. Production of new 3D scaffolds for bone tissue regeneration by rapid prototyping.

    PubMed

    Fradique, R; Correia, T R; Miguel, S P; de Sá, K D; Figueira, D R; Mendonça, A G; Correia, I J

    2016-04-01

    The incidence of bone disorders, whether due to trauma or pathology, has been trending upward with the aging of the worldwide population. The currently available treatments for bone injuries are rather limited, involving mainly bone grafts and implants. A particularly promising approach for bone regeneration uses rapid prototyping (RP) technologies to produce 3D scaffolds with highly controlled structure and orientation, based on computer-aided design models or medical data. Herein, tricalcium phosphate (TCP)/alginate scaffolds were produced using RP and subsequently their physicochemical, mechanical and biological properties were characterized. The results showed that 60/40 of TCP and alginate formulation was able to match the compression and present a similar Young modulus to that of trabecular bone while presenting an adequate biocompatibility. Moreover, the biomineralization ability, roughness and macro and microporosity of scaffolds allowed cell anchoring and proliferation at their surface, as well as cell migration to its interior, processes that are fundamental for osteointegration and bone regeneration.

  3. Physicochemical characterization and biocompatibility of alginate-polycation microcapsules designed for islet transplantation

    NASA Astrophysics Data System (ADS)

    Tam, Susan Kimberly

    diabetic mice. To achieve these aims, extensive physicochemical analyses of the alginates and microcapsules were carried out. Among the properties of the alginates that were investigated include their purity (LAL assay, microBCA), chemical composition (nuclear magnetic resonance, NMR), elemental composition (x-ray photoelectron spectroscopy, XPS), and hydrophilicity (contact angle technique). As for the microcapsules, we also examined their surface chemical composition (XPS), hydrophilicity, as well as alginate-polycation interactions (Fourier transform infrared spectroscopy, FTIR), and membrane strength (osmotic swelling). The results of this research led to a number of important conclusions about the biocompatibility of alginates and alginate-based microcapsules. First of all, purifying an alginate does not guarantee its biocompatibility. Indeed, we provided evidence that both the alginate chemical composition (i.e. relative content of mannuronate and guluronate) and its intrinsic viscosity influence the extent of host cell adhesion to alginate gel beads. Using a biocompatible alginate, we then provided evidence that microcapsule biocompatibility is greatly compromised by its polycationic membrane. We showed that this membrane is responsible for the adsorption of opsonizing proteins in vitro and the adhesion of immune cells in vivo. That said, the severity of inflammatory response to the membrane can vary, and this depended on the microcapsule design, including the choice of alginate and polycation type. Results of our physicochemical analyses suggested that the most important factor determining biocompatibility is the ability of the polycation to diffuse into, and subsequently bind to, the alginate gel core. Moreover, adding a final coating of alginate had no significant effect on reversing the effects of the membrane on various microcapsule properties (surface composition, hydrophobicity, stability), nor did this coating reduce its immunogenicity. Although we

  4. Crystal structure of bacterial cell-surface alginate-binding protein with an M75 peptidase motif

    SciTech Connect

    Maruyama, Yukie; Ochiai, Akihito; Mikami, Bunzo; Hashimoto, Wataru; Murata, Kousaku

    2011-02-18

    Research highlights: {yields} Bacterial alginate-binding Algp7 is similar to component EfeO of Fe{sup 2+} transporter. {yields} We determined the crystal structure of Algp7 with a metal-binding motif. {yields} Algp7 consists of two helical bundles formed through duplication of a single bundle. {yields} A deep cleft involved in alginate binding locates around the metal-binding site. {yields} Algp7 may function as a Fe{sup 2+}-chelated alginate-binding protein. -- Abstract: A gram-negative Sphingomonas sp. A1 directly incorporates alginate polysaccharide into the cytoplasm via the cell-surface pit and ABC transporter. A cell-surface alginate-binding protein, Algp7, functions as a concentrator of the polysaccharide in the pit. Based on the primary structure and genetic organization in the bacterial genome, Algp7 was found to be homologous to an M75 peptidase motif-containing EfeO, a component of a ferrous ion transporter. Despite the presence of an M75 peptidase motif with high similarity, the Algp7 protein purified from recombinant Escherichia coli cells was inert on insulin B chain and N-benzoyl-Phe-Val-Arg-p-nitroanilide, both of which are substrates for a typical M75 peptidase, imelysin, from Pseudomonas aeruginosa. The X-ray crystallographic structure of Algp7 was determined at 2.10 A resolution by single-wavelength anomalous diffraction. Although a metal-binding motif, HxxE, conserved in zinc ion-dependent M75 peptidases is also found in Algp7, the crystal structure of Algp7 contains no metal even at the motif. The protein consists of two structurally similar up-and-down helical bundles as the basic scaffold. A deep cleft between the bundles is sufficiently large to accommodate macromolecules such as alginate polysaccharide. This is the first structural report on a bacterial cell-surface alginate-binding protein with an M75 peptidase motif.

  5. Alginate-modifying enzymes: biological roles and biotechnological uses

    PubMed Central

    Ertesvåg, Helga

    2015-01-01

    Alginate denotes a group of industrially important 1-4-linked biopolymers composed of the C-5-epimers β-D-mannuronic acid (M) and α-L-guluronic acid (G). The polysaccharide is manufactured from brown algae where it constitutes the main structural cell wall polymer. The physical properties of a given alginate molecule, e.g., gel-strength, water-binding capacity, viscosity and biocompatibility, are determined by polymer length, the relative amount and distribution of G residues and the acetyl content, all of which are controlled by alginate modifying enzymes. Alginate has also been isolated from some bacteria belonging to the genera Pseudomonas and Azotobacter, and bacterially synthesized alginate may be O-acetylated at O-2 and/or O-3. Initially, alginate is synthesized as polymannuronic acid, and some M residues are subsequently epimerized to G residues. In bacteria a mannuronan C-5-epimerase (AlgG) and an alginate acetylase (AlgX) are integral parts of the protein complex necessary for alginate polymerization and export. All alginate-producing bacteria use periplasmic alginate lyases to remove alginate molecules aberrantly released to the periplasm. Alginate lyases are also produced by organisms that utilize alginate as carbon source. Most alginate-producing organisms encode more than one mannuronan C-5 epimerase, each introducing its specific pattern of G residues. Acetylation protects against further epimerization and from most alginate lyases. An enzyme from Pseudomonas syringae with alginate deacetylase activity has been reported. Functional and structural studies reveal that alginate lyases and epimerases have related enzyme mechanisms and catalytic sites. Alginate lyases are now utilized as tools for alginate characterization. Secreted epimerases have been shown to function well in vitro, and have been engineered further in order to obtain enzymes that can provide alginates with new and desired properties for use in medical and pharmaceutical applications

  6. Performance evaluation of bipolar and tripolar excitations during nozzle-jetting-based alginate microsphere fabrication

    NASA Astrophysics Data System (ADS)

    Herran, C. Leigh; Huang, Yong; Chai, Wenxuan

    2012-08-01

    Microspheres, small spherical (polymeric) particles with or without second phase materials embedded or encapsulated, are important for many biomedical applications such as drug delivery and organ printing. Scale-up fabrication with the ability to precisely control the microsphere size and morphology has always been of great manufacturing interest. The objective of this work is to experimentally study the performance differences of bipolar and tripolar excitation waveforms in using drop-on-demand (DOD)-based single nozzle jetting for alginate microsphere fabrication. The fabrication performance has been evaluated based on the formability of alginate microspheres as a function of materials properties (sodium alginate and calcium chloride concentrations) and operating conditions. The operating conditions for each excitation include voltage rise/fall times, dwell times and excitation voltage amplitudes. Overall, the bipolar excitation is more robust in making spherical, monodispersed alginate microspheres as good microspheres for its wide working range of material properties and operating conditions, especially during the fabrication of highly viscous materials such as the 2% sodium alginate solution. For both bipolar and tripolar excitations, the sodium alginate concentration and the voltage dwell times should be carefully selected to achieve good microsphere formability.

  7. Doxorubicin-loaded alginate-g-poly(N-isopropylacrylamide) micelles for cancer imaging and therapy.

    PubMed

    Ahn, Dong-Gyun; Lee, Jangwook; Park, So-Young; Kwark, Young-Je; Lee, Kuen Yong

    2014-12-24

    Chemotherapy is a widely adopted method for the treatment of cancer. However, its use is often limited due to side effects produced by anti-cancer drugs. Therefore, various drug carriers, including polymeric micelles, have been investigated to find a method to overcome this limitation. In this study, alginate-based, self-assembled polymeric micelles were designed and prepared using alginate-g-poly(N-isopropylacrylamide) (PNIPAAm). Amino-PNIPAAm was chemically introduced to the alginate backbone via carbodiimide chemistry. The resulting polymer was dissolved in distilled water at room temperature and formed self-assembled micelles at 37 °C. Characteristics of alginate-g-PNIPAAm micelles were dependent on the molecular weight of PNIPAAm, the degree of substitution, and the polymer concentration. Doxorubicin (DOX), a model anti-cancer drug, was efficiently encapsulated in alginate-g-PNIPAAm micelles, and sustained release of DOX from the micelles was achieved at 37 °C in vitro. These micelles accumulated at the tumor site of a tumor-bearing mouse model as a result of the enhanced permeability and retention effect. Interestingly, DOX-loaded alginate-g-PNIPAAm micelles showed excellent anti-cancer therapeutic efficacy in a mouse model without any significant side effects. This approach to designing and tailoring natural polymer-based systems to fabricate nanoparticles at human body temperature may provide a useful means for cancer imaging and therapy. PMID:25487046

  8. One-step synthesis of platinum nanoparticles loaded in alginate bubbles.

    PubMed

    Yang, Chih-Hui; Wang, Wei-Ting; Grumezescu, Alexandru Mihai; Huang, Keng-Shiang; Lin, Yung-Sheng

    2014-01-01

    Composite particles with multifunctions have been extensively utilized for various applications. Bubble particles can be applied for ultrasound-mediated imaging, drug delivery, absorbers, cell culture, etc. This study proposes a one-step strategy to obtain Pt nanoparticles loaded in alginate bubbles. A needle-based droplet formation was used to generate uniform alginate particles about 2 mm in diameter. The hydrolysis reaction of NaBH4 was utilized to produce gaseous hydrogen and then trapped within alginate particles to form bubbles. The Pt(4+) mixed with alginate solution was dropped into the reservoir to react with reducing NaBH4 and hardening CaCl2 to form Pt nanoparticles-alginate composite bubbles. Results indicate that the size of bubbles decreases with the CaCl2 concentration (1% ~ 20%), and size of bubbles increases with the NaBH4 concentration (1 ~ 20 mM). The advantages for the present approach include low cost, easy operation, and effective production of Pt nanoparticles-alginate composite bubbles.

  9. Influence of amino acids, buffers, and ph on the γ-irradiation-induced degradation of alginates.

    PubMed

    Ulset, Ann-Sissel T; Mori, Hideki; Dalheim, Marianne Ø; Hara, Masayuki; Christensen, Bjørn E

    2014-12-01

    Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates' material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy. PMID:25412478

  10. Self-cross-linking biopolymers as injectable in situ forming biodegradable scaffolds.

    PubMed

    Balakrishnan, Biji; Jayakrishnan, A

    2005-06-01

    The injectable polymer scaffolds which are biocompatible and biodegradable are important biomaterials for tissue engineering and drug delivery. Hydrogels derived from natural proteins and polysaccharides are ideal scaffolds for tissue engineering since they resemble the extracellular matrices of the tissue comprised of various amino acids and sugar-based macromolecules. Here, we report a new class of hydrogels derived from oxidized alginate and gelatin. We show that periodate-oxidized sodium alginate having appropriate molecular weight and degree of oxidation rapidly cross-links proteins such as gelatin in the presence of small concentrations of sodium tetraborate (borax) to give injectable systems for tissue engineering, drug delivery and other medical applications. The rapid gelation in the presence of borax is attributed to the slightly alkaline pH of the medium as well as the ability of borax to complex with hydroxyl groups of polysaccharides. The effect of degree of oxidation and concentration of alginate dialdehyde, gelatin and borax on the speed of gelation was examined. As a general rule, the gelling time decreased with increase in concentration of oxidized alginate, gelatin and borax and increase in the degree of oxidation of alginate. Cross-linking parameters of the gel matrix were studied by swelling measurements and trinitrobenzene sulphonic acid (TNBS) assay. In general, the degree of cross-linking was found to increase with increase in the degree of oxidation of alginate, whereas the swelling ratio and the degree of swelling decreased. The gel was found to be biocompatible and biodegradable. The potential of the system as an injectable drug delivery vehicle and as a tissue-engineering scaffold is demonstrated by using primaquine as a model drug and by encapsulation of hepatocytes inside the gel matrix, respectively.

  11. Stapled endosome disrupting alginate particles for cytosolic delivery of cations.

    PubMed

    Acharya, Abhinav P; Little, Steven R

    2015-01-01

    Divalent cations, the most prevalent minerals in the body, are responsible for a wide variety of cellular functions including signaling, proliferation, differentiation and cell death, and therefore their transmembrane transportation is tightly regulated. Despite the importance of divalent cations in cell activity, there are currently no intracellular delivery methods for divalent cations or modulation of intracellular levels of minerals. Here, we describe endosome disrupting alginate nanoparticles termed Alginoketals, which can deliver divalent cations to the cytosol of the cells. Alginoketals are generated by crosslinking alginic acid with endosome disrupting ketals, and using divalent cations as the stapling or binding agent. We show that Alginoketals were able to deliver copper (II) in the cytosol of the cancer cells thereby disrupting copper homeostasis and inducing cell death via accumulation of hydrogen peroxide. Alginoketal-copper (II)-based particles act as superoxide dismutase mimics and are the first class of divalent cation delivery vehicles, with potential application in cancer therapy, regenerative medicine and drug delivery.

  12. Photonic monitoring of chitosan nanostructured alginate microcapsules for drug release

    NASA Astrophysics Data System (ADS)

    Khajuria, Deepak Kumar; Konnur, Manish C.; Vasireddi, Ramakrishna; Roy Mahapatra, D.

    2015-02-01

    By using a novel microfluidic set-up for drug screening applications, this study examines delivery of a novel risedronate based drug formulation for treatment of osteoporosis that was developed to overcome the usual shortcomings of risedronate, such as its low bioavailability and adverse gastric effects. Risedronate nanoparticles were prepared using muco-adhesive polymers such as chitosan as matrix for improving the intestinal cellular absorption of risedronate and also using a gastric-resistant polymer such as sodium alginate for reducing the gastric inflammation of risedronate. The in-vitro characteristics of the alginate encapsulated chitosan nanoparticles are investigated, including their stability, muco-adhesiveness, and Caco-2 cell permeability. Fluorescent markers are tagged with the polymers and their morphology within the microcapsules is imaged at various stages of drug release.

  13. Laser-assisted fabrication of highly viscous alginate microsphere

    NASA Astrophysics Data System (ADS)

    Lin, Yafu; Huang, Yong

    2011-04-01

    Encapsulated microspheres have been widely used in various biomedical applications. However, fabrication of encapsulated microspheres from highly viscous materials has always been a manufacturing challenge. The objective of this study is to explore a novel metallic foil-assisted laser-induced forward transfer (LIFT), a laser-assisted fabrication technique, to make encapsulated microspheres using high sodium alginate concentration solutions. The proposed four-layer approach includes a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a transferred suspension layer. It is found that the proposed four-layer modified LIFT approach provides a promising fabrication technology for making of bead-encapsulated microspheres from highly viscous solutions. During the process, the microsphere only can be formed if the direct-writing height is larger than the critical direct-writing height; otherwise, tail structured droplets are formed; and the encapsulated microsphere diameter linearly increases with the laser fluence and decreases with the sodium alginate concentration.

  14. Chromosome Scaffold is a Double-Stranded Assembly of Scaffold Proteins

    PubMed Central

    Poonperm, Rawin; Takata, Hideaki; Hamano, Tohru; Matsuda, Atsushi; Uchiyama, Susumu; Hiraoka, Yasushi; Fukui, Kiichi

    2015-01-01

    Chromosome higher order structure has been an enigma for over a century. The most important structural finding has been the presence of a chromosome scaffold composed of non-histone proteins; so-called scaffold proteins. However, the organization and function of the scaffold are still controversial. Here, we use three dimensional-structured illumination microscopy (3D-SIM) and focused ion beam/scanning electron microscopy (FIB/SEM) to reveal the axial distributions of scaffold proteins in metaphase chromosomes comprising two strands. We also find that scaffold protein can adaptably recover its original localization after chromosome reversion in the presence of cations. This reversion to the original morphology underscores the role of the scaffold for intrinsic structural integrity of chromosomes. We therefore propose a new structural model of the chromosome scaffold that includes twisted double strands, consistent with the physical properties of chromosomal bending flexibility and rigidity. Our model provides new insights into chromosome higher order structure. PMID:26132639

  15. Functionalized scaffolds to enhance tissue regeneration

    PubMed Central

    Guo, Baolin; Lei, Bo; Li, Peng; Ma, Peter X.

    2015-01-01

    Tissue engineering scaffolds play a vital role in regenerative medicine. It not only provides a temporary 3-dimensional support during tissue repair, but also regulates the cell behavior, such as cell adhesion, proliferation and differentiation. In this review, we summarize the development and trends of functional scaffolding biomaterials including electrically conducting hydrogels and nanocomposites of hydroxyapatite (HA) and bioactive glasses (BGs) with various biodegradable polymers. Furthermore, the progress on the fabrication of biomimetic nanofibrous scaffolds from conducting polymers and composites of HA and BG via electrospinning, deposition and thermally induced phase separation is discussed. Moreover, bioactive molecules and surface properties of scaffolds are very important during tissue repair. Bioactive molecule-releasing scaffolds and antimicrobial surface coatings for biomedical implants and scaffolds are also reviewed. PMID:25844177

  16. Alginate dressing as a donor site haemostat.

    PubMed Central

    Groves, A. R.; Lawrence, J. C.

    1986-01-01

    An alginate fibre dressing has been used to reduce blood loss from skin graft donor sites. Significant haemostasis has been achieved in the immediate post surgery phase and no adverse reactions observed. Images Fig. 1 PMID:3511833

  17. 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.

  18. 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. PMID:26621717

  19. 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

  20. Lead removal in rats using calcium alginate.

    PubMed

    Savchenko, Olga V; Sgrebneva, Marina N; Kiselev, Vladimir I; Khotimchenko, Yuri S

    2015-01-01

    Lead (Pb) exposure, even at low levels, causes a variety of health problems. The aims of this study were to investigate the tissue distribution of lead in the bodies of rats, to evaluate lead removal from the internal organs and bones using calcium alginate in doses of 500, 200 and 100 mg/kg per day for 28 days and to assess the impact of calcium alginate on the level of essential elements. Lead (Pb), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn) levels in the blood, hearts, kidneys, livers and femurs of the experimental animals were measured using mass spectrometry with inductively coupled plasma. The results revealed that lead acetate exposure increased the levels of Pb in the blood and organs of the animals and significantly reduced contents of Ca, Mn, Fe, Cu and Zn. Treatment with calcium alginate in dose 500 mg/kg contributed to significant decreases in the amount of lead in the kidney, heart and bones of animals and a slight increase in the content of essential elements in the liver, kidneys and heart, although these changes were not significant. Decreasing of lead was not significant in the internal organs, bones and blood of animals treated with calcium alginate 200 and 100 mg/kg. Consequently, calcium alginate dose of 500 mg/kg more efficiently removes lead accumulated in the body. Calcium alginate does not have negative effect on level of essential elements quite the contrary; reducing the levels of lead, calcium alginate helps normalize imbalances of Ca, Mn, Fe, Cu and Zn. The results of this study suggest that calcium alginate may potentially be useful for the treatment and prevention of heavy metal intoxications. PMID:25062547

  1. Freeze-thaw induced gelation of alginates.

    PubMed

    Zhao, Ying; Shen, Wei; Chen, Zhigang; Wu, Tao

    2016-09-01

    Adding divalent ions or lowering pH below the pKa values of alginate monomers are common ways in preparing alginate gels. Herein a new way of preparing alginate gels using freeze-thaw technique is described. Solvent crystallization during freezing drove the polymers to associate into certain structures that became the junction zones of hydrogels after thawing. It enabled the preparation of alginate gels at pH 4.0 and 3.5, two pH at which the gel could not be formed previously. At pH 3.0 where alginate gel could be formed initially, applying freeze-thaw treatment increased the gel storage modulus almost 100 times. The formation of hydrogels and the resulting gel properties, such as dynamic moduli and gel syneresis were influenced by the pH values, number of freeze-thaw cycles, alginate concentrations, and ionic strengths. The obtained hydrogels were soft and demonstrated a melting behavior upon storage, which may find novel applications in the biomedical industry.

  2. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    NASA Astrophysics Data System (ADS)

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-01-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %.

  3. Development of porous scaffolds for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Ramay, Hassna Rehman

    -liquid phase separation technique with a polyelectrolyte complex of chitosan and alginate as scaffolding material. These scaffolds were used to study sustained delivery of a model protein. The effect of size of ceramic in polymer matrix on mechanical and biological properties of scaffold is also examined by using both nano- and micron-sized ceramic particles.

  4. Three-dimensional electrospun alginate nanofiber mats via tailored charge repulsions.

    PubMed

    Bonino, Christopher A; Efimenko, Kirill; Jeong, Sung In; Krebs, Melissa D; Alsberg, Eben; Khan, Saad A

    2012-06-25

    The formation of 3D electrospun mat structures from alginate-polyethylene oxide (PEO) solution blends is reported. These unique architectures expand the capabilities of traditional electrospun mats for applications such as regenerative medicine, where a scaffold can help to promote tissue growth in three dimensions. The mat structures extend off the surface of the flat collector plate without the need of any modifications in the electrospinning apparatus, are self-supported when the electric field is removed, and are composed of bundles of nanofibers. A mechanism for the unique formations is proposed, based on the fiber-fiber repulsions from surface charges on the negatively charged alginate. Furthermore, the role of the electric field in the distribution of alginate within the nanofibers is discussed. X-ray photoelectron spectroscopy is used to analyze the surface composition of the electrospun nanofiber mats and the data is related to cast films made in the absence of the electric field. Further techniques to tailor the 3D architecture and nanofiber morphology by changing the surface tension and relative humidity are also discussed.

  5. [Applications of Porous Scaffolds in Muscle Tissue Engineering].

    PubMed

    Sun, Yan; Zou, Ling; Liu, Jun

    2015-12-01

    Scaffold is one of the key elements required for tissue engineering. Porous scaffolds have several special advantages for muscle tissue engineering, and they are beneficial to cell survival, myogenic differentiation, and vascular ingrowth. The performance of porous scaffolds is closely related to the property of the biomaterials used. Additionally, the pore size and porosity may affect cell adhesion, proliferation, and differentiation. This review focuses on the application of porous scaffolds in muscle tissue engineering, including their categories, application, and advantages.

  6. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions. PMID:26878165

  7. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions.

  8. Facile fabrication of organic-inorganic hybrid beads by aminated alginate enabled gelation and biomimetic mineralization.

    PubMed

    Li, Jian; Wu, Hong; Liang, Yanpeng; Jiang, Zhongyi; Jiang, Yanjun; Zhang, Lei

    2013-01-01

    Inspired by biomineralization, design and preparation of biomimetic organic-inorganic composites have become a hot issue and a research frontier in many areas, including enzyme engineering. In this research, a unique and facile method for fabricating organic-inorganic hybrid beads is proposed. Modified alginate with a dual function of gelation and mineralization was synthesized for fabrication of hybrid carriers for enzyme immobilization. With the aid of EDC/NHS conjugation chemistry, the amine groups from diethylene triamine were grafted onto alginate in a controllable way. The resultant aminated alginate served manifold functions: forming a hydrogel via Ca(2+)-cross-linking, inducing the biomimetic silicification and manipulating the distribution of silica nanoparticles. Owing to the compact polymer network structure and the homogeneous silica nanoparticle dispersion, the as-prepared NH2-alginate/silica hybrid beads displayed superior swelling resistance and mechanical stability to pure alginate beads. The hybrid beads were subsequently utilized for encapsulation of yeast alcohol dehydrogenase (YADH). It was found that the thermal stability, pH tolerance and storage stability of the immobilized enzyme were all improved without significantly lowering the catalytic activity.

  9. Effects of alginate hydrogel cross-linking density on mechanical and biological behaviors for tissue engineering.

    PubMed

    Jang, Jinah; Seol, Young-Joon; Kim, Hyeon Ji; Kundu, Joydip; Kim, Sung Won; Cho, Dong-Woo

    2014-09-01

    An effective cross-linking of alginate gel was made through reaction with calcium carbonate (CaCO3). We used human chondrocytes as a model cell to study the effects of cross-linking density. Three different pore size ranges of cross-linked alginate hydrogels were fabricated. The morphological, mechanical, and rheological properties of various alginate hydrogels were characterized and responses of biosynthesis of cells encapsulated in each gel to the variation in cross-linking density were investigated. Desired outer shape of structure was maintained when the alginate solution was cross-linked with the applied method. The properties of alginate hydrogel could be tailored through applying various concentrations of CaCO3. The rate of synthesized GAGs and collagens was significantly higher in human chondrocytes encapsulated in the smaller pore structure than that in the larger pore structure. The expression of chondrogenic markers, including collagen type II and aggrecan, was enhanced in the smaller pore structure. It was found that proper structural morphology is a critical factor to enhance the performance and tissue regeneration.

  10. Evaluation of novel in situ synthesized nano-hydroxyapatite/collagen/alginate hydrogels for osteochondral tissue engineering.

    PubMed

    Zheng, Li; Jiang, Xianfang; Chen, Xuening; Fan, Hongsong; Zhang, Xingdong

    2014-12-01

    Collagen hydrogel has been widely used for osteochondral repair, but its mechanical properties cannot meet the requirements of clinical application. Previous studies have shown that the addition of either polysaccharide or inorganic particles could reinforce the polymer matrix. However, their synergic effects on collagen-based hydrogel have seldom been studied, and the potential application of triple-phased composite gel in osteochondral regeneration has not been reported. In this study, nano-hydroxyapatite (nano-HA) reinforced collagen-alginate hydrogel (nHCA) was prepared by the in situ synthesis of nano-HA in collagen gel followed by the addition of alginate and Ca(2+). The properties of triple-phased nHCA hydrogel were studied and compared with pure collagen and biphasic gels, and the triple-phased composite of collagen-alginate-HA gels showed a superiority in not only mechanical but also biological features, as evidenced by the enhanced tensile and compressive modulus, higher cell viability, faster cell proliferation and upregulated hyaline cartilage markers. In addition, it was found that the synthesis process could also affect the properties of the triple-phased composite, compared to blend-mixing HCA. The in situ-synthesized nHCA hydrogel showed an enhanced tensile modulus, as well as enhanced biological features compared with HCA. Our study demonstrated that the nHCA composite hydrogel holds promise in osteochondral regeneration. The addition of alginate and nano-HA contribute to the increase in both mechanical and biological properties. This study may provide a valuable reference for the design of an appropriate composite scaffold for osteochondral tissue engineering.

  11. Biomimetic magnetic silk scaffolds.

    PubMed

    Samal, Sangram K; Dash, Mamoni; Shelyakova, Tatiana; Declercq, Heidi A; Uhlarz, Marc; Bañobre-López, Manuel; Dubruel, Peter; Cornelissen, Maria; Herrmannsdörfer, Thomas; Rivas, Jose; Padeletti, Giuseppina; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-03-25

    Magnetic silk fibroin protein (SFP) scaffolds integrating magnetic materials and featuring magnetic gradients were prepared for potential utility in magnetic-field assisted tissue engineering. Magnetic nanoparticles (MNPs) were introduced into SFP scaffolds via dip-coating methods, resulting in magnetic SFP scaffolds with different strengths of magnetization. Magnetic SFP scaffolds showed excellent hyperthermia properties achieving temperature increases up to 8 °C in about 100 s. The scaffolds were not toxic to osteogenic cells and improved cell adhesion and proliferation. These findings suggest that tailored magnetized silk-based biomaterials can be engineered with interesting features for biomaterials and tissue-engineering applications.

  12. Versatile modular scaffolds

    NASA Technical Reports Server (NTRS)

    Kerley, J.

    1981-01-01

    Movable and fixed modular scaffolds can be tailored to most scaffolding needs by interconnecting only 4 basic structural elements: platforms, rails, vertical-support angles, and stiffener. Standard nuts and bolts are used to join elements, simplifying construction, and reducing costs. Scaffolds are rigid and can be made any length. They are stable on unlevel ground and can extend to well over 50 feet in height. Scaffolds allow for internal elevators and for wheels and air mounts so that same elements can be used for standing or movable scaffold.

  13. Cloning of Pseudomonas aeruginosa algG, which controls alginate structure.

    PubMed Central

    Chitnis, C E; Ohman, D E

    1990-01-01

    The biochemical mechanism by which alpha-L-guluronate (G) residues are incorporated into alginate by Pseudomonas aeruginosa is not understood. P. aeruginosa first synthesizes GDP-mannuronate, which is used to incorporate beta-D-mannuronate residues into the polymer. It is likely that the conversion of some beta-D-mannuronate residues to G occurs by the action of a C-5 epimerase at either the monomer (e.g., sugar-nucleotide) or the polymer level. This study describes the results of a molecular genetic approach to identify a gene involved in the formation or incorporation of G residues into alginate by P. aeruginosa. Mucoid P. aeruginosa FRD1 was chemically mutagenized, and mutants FRD462 and FRD465, which were incapable of incorporating G residues into alginate, were independently isolated. Assays using a G-specific alginate lyase from Klebsiella aerogenes and 1H-nuclear magnetic resonance analyses showed that G residues were absent in the alginates secreted by these mutants. 1H-nuclear magnetic resonance analyses also showed that alginate from wild-type P. aeruginosa contained no detectable blocks of G. The mutations responsible for defective incorporation of G residues into alginate in the mutants FRD462 and FRD465 were designated algG4 and algG7, respectively. Genetic mapping experiments revealed that algG was closely linked (greater than 90%) to argF, which lies at 34 min on the P. aeruginosa chromosome and is adjacent to a cluster of genes required for alginate biosynthesis. The clone pALG2, which contained 35 kilobases of P. aeruginosa DNA that included the algG and argF wild-type alleles, was identified from a P. aeruginosa gene bank by a screening method that involved gene replacement. A DNA fragment carrying algG was shown to complement algG4 and algG7 in trans. The algG gene was physically mapped on the alginate gene cluster by subcloning and Tn501 mutagenesis. Images PMID:2160929

  14. Enzymatic Hydrolysis of Alginate to Produce Oligosaccharides by a New Purified Endo-Type Alginate Lyase

    PubMed Central

    Zhu, Benwei; Chen, Meijuan; Yin, Heng; Du, Yuguang; Ning, Limin

    2016-01-01

    Enzymatic hydrolysis of sodium alginate to produce alginate oligosaccharides has drawn increasing attention due to its advantages of containing a wild reaction condition, excellent gel properties and specific products easy for purification. However, the efficient commercial enzyme tools are rarely available. A new alginate lyase with high activity (24,038 U/mg) has been purified from a newly isolated marine strain, Cellulophaga sp. NJ-1. The enzyme was most active at 50 °C and pH 8.0 and maintained stability at a broad pH range (6.0–10.0) and temperature below 40 °C. It had broad substrate specificity toward sodium alginate, heteropolymeric MG blocks (polyMG), homopolymeric M blocks (polyM) and homopolymeric G blocks (polyG), and possessed higher affinity toward polyG (15.63 mM) as well as polyMG (23.90 mM) than polyM (53.61 mM) and sodium alginate (27.21 mM). The TLC and MS spectroscopy analysis of degradation products suggested that it completely hydrolyzed sodium alginate into oligosaccharides of low degrees of polymerization (DPs). The excellent properties would make it a promising tool for full use of sodium alginate to produce oligosaccharides. PMID:27275826

  15. Silk scaffolds for musculoskeletal tissue engineering

    PubMed Central

    Yao, Danyu

    2015-01-01

    The musculoskeletal system, which includes bone, cartilage, tendon/ligament, and skeletal muscle, is becoming the targets for tissue engineering because of the high need for their repair and regeneration. Numerous factors would affect the use of musculoskeletal tissue engineering for tissue regeneration ranging from cells used for scaffold seeding to the manufacture and structures of materials. The essential function of the scaffolds is to convey growth factors as well as cells to the target site to aid the regeneration of the injury. Among the variety of biomaterials used in scaffold engineering, silk fibroin is recognized as an ideal material for its impressive cytocompatibility, slow biodegradability, and excellent mechanical properties. The current review describes the advances made in the fabrication of silk fibroin scaffolds with different forms such as films, particles, electrospun fibers, hydrogels, three-dimensional porous scaffolds, and their applications in the regeneration of musculoskeletal tissues. PMID:26445979

  16. Silk scaffolds for musculoskeletal tissue engineering.

    PubMed

    Yao, Danyu; Liu, Haifeng; Fan, Yubo

    2016-02-01

    The musculoskeletal system, which includes bone, cartilage, tendon/ligament, and skeletal muscle, is becoming the targets for tissue engineering because of the high need for their repair and regeneration. Numerous factors would affect the use of musculoskeletal tissue engineering for tissue regeneration ranging from cells used for scaffold seeding to the manufacture and structures of materials. The essential function of the scaffolds is to convey growth factors as well as cells to the target site to aid the regeneration of the injury. Among the variety of biomaterials used in scaffold engineering, silk fibroin is recognized as an ideal material for its impressive cytocompatibility, slow biodegradability, and excellent mechanical properties. The current review describes the advances made in the fabrication of silk fibroin scaffolds with different forms such as films, particles, electrospun fibers, hydrogels, three-dimensional porous scaffolds, and their applications in the regeneration of musculoskeletal tissues.

  17. Encapsulated dental-derived mesenchymal stem cells in an injectable and biodegradable scaffold for applications in bone tissue engineering.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Akiyama, Kentaro; Xu, Xingtian; Chee, Winston W L; Schricker, Scott R; Shi, Songtao

    2013-11-01

    Bone grafts are currently the major family of treatment options in modern reconstructive dentistry. As an alternative, stem cell-scaffold constructs seem to hold promise for bone tissue engineering. However, the feasibility of encapsulating dental-derived mesenchymal stem cells in scaffold biomaterials such as alginate hydrogel remains to be tested. The objectives of this study were, therefore, to: (1) develop an injectable scaffold based on oxidized alginate microbeads encapsulating periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs); and (2) investigate the cell viability and osteogenic differentiation of the stem cells in the microbeads both in vitro and in vivo. Microbeads with diameters of 1 ± 0.1 mm were fabricated with 2 × 10(6) stem cells/mL of alginate. Microbeads containing PDLSCs, GMSCs, and human bone marrow mesenchymal stem cells as a positive control were implanted subcutaneously and ectopic bone formation was analyzed by micro CT and histological analysis at 8-weeks postimplantation. The encapsulated stem cells remained viable after 4 weeks of culturing in osteo-differentiating induction medium. Scanning electron microscopy and X-ray diffraction results confirmed that apatitic mineral was deposited by the stem cells. In vivo, ectopic mineralization was observed inside and around the implanted microbeads containing the immobilized stem cells. These findings demonstrate for the first time that immobilization of PDLSCs and GMSCs in alginate microbeads provides a promising strategy for bone tissue engineering. PMID:23983201

  18. Composite scaffolds for cartilage tissue engineering.

    PubMed

    Moutos, Franklin T; Guilak, Farshid

    2008-01-01

    Tissue engineering remains a promising therapeutic strategy for the repair or regeneration of diseased or damaged tissues. Previous approaches have typically focused on combining cells and bioactive molecules (e.g., growth factors, cytokines and DNA fragments) with a biomaterial scaffold that functions as a template to control the geometry of the newly formed tissue, while facilitating the attachment, proliferation, and differentiation of embedded cells. Biomaterial scaffolds also play a crucial role in determining the functional properties of engineered tissues, including biomechanical characteristics such as inhomogeneity, anisotropy, nonlinearity or viscoelasticity. While single-phase, homogeneous materials have been used extensively to create numerous types of tissue constructs, there continue to be significant challenges in the development of scaffolds that can provide the functional properties of load-bearing tissues such as articular cartilage. In an attempt to create more complex scaffolds that promote the regeneration of functional engineered tissues, composite scaffolds comprising two or more distinct materials have been developed. This paper reviews various studies on the development and testing of composite scaffolds for the tissue engineering of articular cartilage, using techniques such as embedded fibers and textiles for reinforcement, embedded solid structures, multi-layered designs, or three-dimensionally woven composite materials. In many cases, the use of composite scaffolds can provide unique biomechanical and biological properties for the development of functional tissue engineering scaffolds.

  19. Recombinant protein scaffolds for tissue engineering.

    PubMed

    Werkmeister, Jerome A; Ramshaw, John A M

    2012-02-01

    New biological materials for tissue engineering are now being developed using common genetic engineering capabilities to clone and express a variety of genetic elements that allow cost-effective purification and scaffold fabrication from these recombinant proteins, peptides or from chimeric combinations of these. The field is limitless as long as the gene sequences are known. The utility is dependent on the ease, product yield and adaptability of these protein products to the biomedical field. The development of recombinant proteins as scaffolds, while still an emerging technology with respect to commercial products, is scientifically superior to current use of natural materials or synthetic polymer scaffolds, in terms of designing specific structures with desired degrees of biological complexities and motifs. In the field of tissue engineering, next generation scaffolds will be the key to directing appropriate tissue regeneration. The initial period of biodegradable synthetic scaffolds that provided shape and mechanical integrity, but no biological information, is phasing out. The era of protein scaffolds offers distinct advantages, particularly with the combination of powerful tools of molecular biology. These include, for example, the production of human proteins of uniform quality that are free of infectious agents and the ability to make suitable quantities of proteins that are found in low quantity or are hard to isolate from tissue. For the particular needs of tissue engineering scaffolds, fibrous proteins like collagens, elastin, silks and combinations of these offer further advantages of natural well-defined structural scaffolds as well as endless possibilities of controlling functionality by genetic manipulation.

  20. Microencapsulation in Alginate and Chitosan Microgels to Enhance Viability of Bifidobacterium longum for Oral Delivery

    PubMed Central

    Yeung, Timothy W.; Üçok, Elif F.; Tiani, Kendra A.; McClements, David J.; Sela, David A.

    2016-01-01

    Probiotic microorganisms are incorporated into a wide variety of foods, supplements, and pharmaceuticals to promote human health and wellness. However, maintaining bacterial cell viability during storage and gastrointestinal transit remains a challenge. Encapsulation of bifidobacteria within food-grade hydrogel particles potentially mitigates their sensitivity to environmental stresses. In this study, Bifidobacterium longum subspecies and strains were encapsulated in core-shell microgels consisting of an alginate core and a microgel shell. Encapsulated obligate anaerobes Bifidobacterium longum subsp. infantis and Bifidobacterium longum subsp. longum exhibited differences in viability in a strain-dependent manner, without a discernable relationship to subspecies lineage. This includes viability under aerobic storage conditions and modeled gastrointestinal tract conditions. Coating alginate microgels with chitosan did not improve viability compared to cells encapsulated in alginate microgels alone, suggesting that modifying the surface charge alone does not enhance delivery. Thus hydrogel beads have great potential for improving the stability and efficacy of bifidobacterial probiotics in various nutritional interventions. PMID:27148184

  1. Designing a highly efficient chemical chaperone system using chitosan-coated alginate.

    PubMed

    Khodagholi, Fariba; Farahmand, Shahrzad; Tusi, Solaleh Khoramian

    2010-07-01

    In the present work we prepared chitosan-coated alginate beads, to use as a chemical chaperone based on the electrostatic interaction between the carboxylate groups of alginate and the ammonium groups of chitosan. This procedure was an attempt for designing a highly efficient chemical chaperone to improve protein stability and refolding. Based on enzyme recovered activity, turbidity, far-UV CD and fluorescence data, alkaline phosphatase can be stabilized and refolded to a higher degree in the presence of alginate capsules compared with unassisted form and was further improved by including chitosan. Finally the maximum yield was obtained when the refolding process was achieved under a well worked out temperature program: incubation of the captured-enzyme for 20 min at 4 degrees C followed by overnight incubation at 22 degrees C, which showed that aggregation is a major limitation to refolding.

  2. Role of Calcium Alginate and Mannitol in Protecting Bifidobacterium

    PubMed Central

    Dianawati, Dianawati; Mishra, Vijay

    2012-01-01

    Fourier transform infrared (FTIR) spectroscopy was carried out to ascertain the mechanism of Ca-alginate and mannitol protection of cell envelope components and secondary proteins of Bifidobacterium animalis subsp. lactis Bb12 after freeze-drying and after 10 weeks of storage at room temperature (25°C) at low water activities (aw) of 0.07, 0.1, and 0.2. Preparation of Ca-alginate and Ca-alginate-mannitol as microencapsulants was carried out by dropping an alginate or alginate-mannitol emulsion containing bacteria using a burette into CaCl2 solution to obtain Ca-alginate beads and Ca-alginate-mannitol beads, respectively. The wet beads were then freeze-dried. The aw of freeze-dried beads was then adjusted to 0.07, 0.1, and 0.2 using saturated salt solutions; controls were prepared by keeping Ca-alginate and Ca-alginate-mannitol in aluminum foil without aw adjustment. Mannitol in the Ca-alginate system interacted with cell envelopes during freeze-drying and during storage at low aws. In contrast, Ca-alginate protected cell envelopes after freeze-drying but not during 10-week storage. Unlike Ca-alginate, Ca-alginate-mannitol was effective in retarding the changes in secondary proteins during freeze-drying and during 10 weeks of storage at low aws. It appears that Ca-alginate-mannitol is more effective than Ca-alginate in preserving cell envelopes and proteins after freeze-drying and after 10 weeks of storage at room temperature (25°C). PMID:22843535

  3. Role of calcium alginate and mannitol in protecting Bifidobacterium.

    PubMed

    Dianawati, Dianawati; Mishra, Vijay; Shah, Nagendra P

    2012-10-01

    Fourier transform infrared (FTIR) spectroscopy was carried out to ascertain the mechanism of Ca-alginate and mannitol protection of cell envelope components and secondary proteins of Bifidobacterium animalis subsp. lactis Bb12 after freeze-drying and after 10 weeks of storage at room temperature (25°C) at low water activities (a(w)) of 0.07, 0.1, and 0.2. Preparation of Ca-alginate and Ca-alginate-mannitol as microencapsulants was carried out by dropping an alginate or alginate-mannitol emulsion containing bacteria using a burette into CaCl(2) solution to obtain Ca-alginate beads and Ca-alginate-mannitol beads, respectively. The wet beads were then freeze-dried. The a(w) of freeze-dried beads was then adjusted to 0.07, 0.1, and 0.2 using saturated salt solutions; controls were prepared by keeping Ca-alginate and Ca-alginate-mannitol in aluminum foil without a(w) adjustment. Mannitol in the Ca-alginate system interacted with cell envelopes during freeze-drying and during storage at low a(w)s. In contrast, Ca-alginate protected cell envelopes after freeze-drying but not during 10-week storage. Unlike Ca-alginate, Ca-alginate-mannitol was effective in retarding the changes in secondary proteins during freeze-drying and during 10 weeks of storage at low a(w)s. It appears that Ca-alginate-mannitol is more effective than Ca-alginate in preserving cell envelopes and proteins after freeze-drying and after 10 weeks of storage at room temperature (25°C). PMID:22843535

  4. Properties and active substance release kinetics from gelatin-alginate matrices.

    PubMed

    Pluta, Janusz; Haznar, Dorota

    2006-01-01

    The aim of the study was to evaluate the effect of composition and technological processing on pharmaceutical availability of active substance as well as on the properties of porous gelatin-alginate matrices. The active substance carrier included glycerol or peanut oil apart from gelatin and sodium alginate, and some matrices were additionally modified with calcium lactate. The obtained matrices were characterized by good sorption properties and high resistance to proteolytic enzymes. The release of the model antibiotic followed the pattern of first order kinetics, while half-release time in vitro (in the experimental conditions) was 1.5 to 3 hrs.

  5. Stereolithographic Bone Scaffold Design Parameters: Osteogenic Differentiation and Signal Expression

    PubMed Central

    Kim, Kyobum; Yeatts, Andrew; Dean, David

    2010-01-01

    Scaffold design parameters including porosity, pore size, interconnectivity, and mechanical properties have a significant influence on osteogenic signal expression and differentiation. This review evaluates the influence of each of these parameters and then discusses the ability of stereolithography (SLA) to be used to tailor scaffold design to optimize these parameters. Scaffold porosity and pore size affect osteogenic cell signaling and ultimately in vivo bone tissue growth. Alternatively, scaffold interconnectivity has a great influence on in vivo bone growth but little work has been done to determine if interconnectivity causes changes in signaling levels. Osteogenic cell signaling could be also influenced by scaffold mechanical properties such as scaffold rigidity and dynamic relationships between the cells and their extracellular matrix. With knowledge of the effects of these parameters on cellular functions, an optimal tissue engineering scaffold can be designed, but a proper technology must exist to produce this design to specification in a repeatable manner. SLA has been shown to be capable of fabricating scaffolds with controlled architecture and micrometer-level resolution. Surgical implantation of these scaffolds is a promising clinical treatment for successful bone regeneration. By applying knowledge of how scaffold parameters influence osteogenic cell signaling to scaffold manufacturing using SLA, tissue engineers may move closer to creating the optimal tissue engineering scaffold. PMID:20504065

  6. A nano-micro alternating multilayer scaffold loading with rBMSCs and BMP-2 for bone tissue engineering.

    PubMed

    Ding, Shan; Li, Long; Liu, Xian; Yang, Guang; Zhou, Guangliang; Zhou, Shaobing

    2015-09-01

    In this study, we develop a nano-micro alternating multilayer scaffold for bone tissue engineering by incorporation of monodispersed calcium alginate microbeads into electrospun polymer nanofibers. Both rat bone marrow mesenchymal stem cells (rBMSCs) and bone morphogenetic protein-2 (BMP-2) are simultaneously loaded into the microbeads, which are generated from a microfluidic device. The layer number of the scaffold can be readily controlled by alternately repeating the electrospinning and the microfluidic processes. Alkaline phosphatase (ALP) activity and Alizarin Red S staining results demonstrate that this rBMSCs and BMP-2 loaded nano-micro alternating multilayer scaffold presents an outstanding osteogenic effect in vitro. Histological and immunohistochemical assessments further reveal that this multilayer scaffold has a significant capability of ectopic bone formation in vivo, enabling this newly developed scaffold to be suitable for wide applications in tissue engineering.

  7. Novel bilayer bacterial nanocellulose scaffold supports neocartilage formation in vitro and in vivo.

    PubMed

    Martínez Ávila, Héctor; Feldmann, Eva-Maria; Pleumeekers, Mieke M; Nimeskern, Luc; Kuo, Willy; de Jong, Willem C; Schwarz, Silke; Müller, Ralph; Hendriks, Jeanine; Rotter, Nicole; van Osch, Gerjo J V M; Stok, Kathryn S; Gatenholm, Paul

    2015-03-01

    Tissue engineering provides a promising alternative therapy to the complex surgical reconstruction of auricular cartilage by using ear-shaped autologous costal cartilage. Bacterial nanocellulose (BNC) is proposed as a promising scaffold material for auricular cartilage reconstruction, as it exhibits excellent biocompatibility and secures tissue integration. Thus, this study evaluates a novel bilayer BNC scaffold for auricular cartilage tissue engineering. Bilayer BNC scaffolds, composed of a dense nanocellulose layer joined with a macroporous composite layer of nanocellulose and alginate, were seeded with human nasoseptal chondrocytes (NC) and cultured in vitro for up to 6 weeks. To scale up for clinical translation, bilayer BNC scaffolds were seeded with a low number of freshly isolated (uncultured) human NCs combined with freshly isolated human mononuclear cells (MNC) from bone marrow in alginate and subcutaneously implanted in nude mice for 8 weeks. 3D morphometric analysis showed that bilayer BNC scaffolds have a porosity of 75% and mean pore size of 50 ± 25 μm. Furthermore, endotoxin analysis and in vitro cytotoxicity testing revealed that the produced bilayer BNC scaffolds were non-pyrogenic (0.15 ± 0.09 EU/ml) and non-cytotoxic (cell viability: 97.8 ± 4.7%). This study demonstrates that bilayer BNC scaffolds offer a good mechanical stability and maintain a structural integrity while providing a porous architecture that supports cell ingrowth. Moreover, bilayer BNC scaffolds provide a suitable environment for culture-expanded NCs as well as a combination of freshly isolated NCs and MNCs to form cartilage in vitro and in vivo as demonstrated by immunohistochemistry, biochemical and biomechanical analyses. PMID:25617132

  8. Novel bilayer bacterial nanocellulose scaffold supports neocartilage formation in vitro and in vivo.

    PubMed

    Martínez Ávila, Héctor; Feldmann, Eva-Maria; Pleumeekers, Mieke M; Nimeskern, Luc; Kuo, Willy; de Jong, Willem C; Schwarz, Silke; Müller, Ralph; Hendriks, Jeanine; Rotter, Nicole; van Osch, Gerjo J V M; Stok, Kathryn S; Gatenholm, Paul

    2015-03-01

    Tissue engineering provides a promising alternative therapy to the complex surgical reconstruction of auricular cartilage by using ear-shaped autologous costal cartilage. Bacterial nanocellulose (BNC) is proposed as a promising scaffold material for auricular cartilage reconstruction, as it exhibits excellent biocompatibility and secures tissue integration. Thus, this study evaluates a novel bilayer BNC scaffold for auricular cartilage tissue engineering. Bilayer BNC scaffolds, composed of a dense nanocellulose layer joined with a macroporous composite layer of nanocellulose and alginate, were seeded with human nasoseptal chondrocytes (NC) and cultured in vitro for up to 6 weeks. To scale up for clinical translation, bilayer BNC scaffolds were seeded with a low number of freshly isolated (uncultured) human NCs combined with freshly isolated human mononuclear cells (MNC) from bone marrow in alginate and subcutaneously implanted in nude mice for 8 weeks. 3D morphometric analysis showed that bilayer BNC scaffolds have a porosity of 75% and mean pore size of 50 ± 25 μm. Furthermore, endotoxin analysis and in vitro cytotoxicity testing revealed that the produced bilayer BNC scaffolds were non-pyrogenic (0.15 ± 0.09 EU/ml) and non-cytotoxic (cell viability: 97.8 ± 4.7%). This study demonstrates that bilayer BNC scaffolds offer a good mechanical stability and maintain a structural integrity while providing a porous architecture that supports cell ingrowth. Moreover, bilayer BNC scaffolds provide a suitable environment for culture-expanded NCs as well as a combination of freshly isolated NCs and MNCs to form cartilage in vitro and in vivo as demonstrated by immunohistochemistry, biochemical and biomechanical analyses.

  9. Composite alginate gels for tunable cellular microenvironment mechanics

    PubMed Central

    Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

    2016-01-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4–12 kPa) as compared to healthy tissue (E = 0.4–2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation. PMID:27484403

  10. Composite alginate gels for tunable cellular microenvironment mechanics.

    PubMed

    Khavari, Adele; Nydén, Magnus; Weitz, David A; Ehrlicher, Allen J

    2016-01-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4-12 kPa) as compared to healthy tissue (E = 0.4-2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation. PMID:27484403

  11. Composite alginate gels for tunable cellular microenvironment mechanics.

    PubMed

    Khavari, Adele; Nydén, Magnus; Weitz, David A; Ehrlicher, Allen J

    2016-08-03

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4-12 kPa) as compared to healthy tissue (E = 0.4-2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation.

  12. Composite alginate gels for tunable cellular microenvironment mechanics

    NASA Astrophysics Data System (ADS)

    Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

    2016-08-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4–12 kPa) as compared to healthy tissue (E = 0.4–2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation.

  13. In Vivo Assessment of Bone Regeneration in Alginate/Bone ECM Hydrogels with Incorporated Skeletal Stem Cells and Single Growth Factors

    PubMed Central

    Gothard, David; Smith, Emma L.; Kanczler, Janos M.; Black, Cameron R.; Wells, Julia A.; Roberts, Carol A.; White, Lisa J.; Qutachi, Omar; Peto, Heather; Rashidi, Hassan; Rojo, Luis; Stevens, Molly M.; El Haj, Alicia J.; Rose, Felicity R. A. J.; Shakesheff, Kevin M.; Oreffo, Richard O. C.

    2015-01-01

    The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-β3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors. PMID:26675008

  14. In Vivo Assessment of Bone Regeneration in Alginate/Bone ECM Hydrogels with Incorporated Skeletal Stem Cells and Single Growth Factors.

    PubMed

    Gothard, David; Smith, Emma L; Kanczler, Janos M; Black, Cameron R; Wells, Julia A; Roberts, Carol A; White, Lisa J; Qutachi, Omar; Peto, Heather; Rashidi, Hassan; Rojo, Luis; Stevens, Molly M; El Haj, Alicia J; Rose, Felicity R A J; Shakesheff, Kevin M; Oreffo, Richard O C

    2015-01-01

    The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-β3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors. PMID:26675008

  15. Vascular Smooth Muscle Cell Optimization of Vasculogenesis within Naturally Derived, Biodegradable Hybrid Hydrogel Scaffolds

    PubMed Central

    Reiffel, Alyssa J.; Perez, Justin L.; Fullerton, Natalia; Lekic, Nikola; Campbell, Rachel; Spector, Jason A.

    2013-01-01

    BACKGROUND As vascularization represents the rate-limiting step in permanent incorporation of hydrogel-based tissue-regeneration templates, we sought to identify the material chemistry that would optimize endothelial cell adhesion and invasion into custom hydrogel constructs. We further investigated induction of endothelial tubule formation by growth factor supplementation and paracrine stimulation. METHODS Hydrogel scaffolds consisting of combinations of alginate, collagen type I, and chitosan were seeded with human umbilical vein endothelial cells (HUVEC) and maintained under standard conditions for 14d. Cell density and invasion were then evaluated. Tubule formation was evaluated following basic fibroblast growth factor (bFGF) addition or co-culture with human aortic smooth muscle cells (HASMC). RESULTS HUVECs demonstrated greatest cell-surface density and invasion volumes with alginate+collagen 10:1 w/w scaffolds (p<0.05). Supplementation with bFGF increased surface-density but neither invasion nor tubule formation. A significant increase in tubule content/organization was observed with increasing HASMC:HUVEC ratio co-culture. CONCLUSIONS Alginate+collagen 10:1 scaffolds allow for maximal cellularization compared with other combinations studied. Growth factor supplementation did not affect HUVEC invasion or morphology. Paracrine signaling via co-culture with HASMC stimulated endothelial tubule formation and vascular proto-network organization. These findings serve to guide our future endeavors towards fabrication of pre-vascularized tissue constructs. PMID:24281642

  16. Alginate hydrogel-mediated crystallization of calcium carbonate

    SciTech Connect

    Ma, Yufei; Feng, Qingling

    2011-05-15

    We documented a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system for the purpose of understanding the mediating function of alginate on the crystallization of calcium carbonate. The alginate was involved in the nucleation and the growth process of CaCO{sub 3}. The crystal size, morphology and roughness of crystal surface were significantly influenced by the type of the alginate, which could be accounted for by the length of the G blocks in alginate. A combination of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that there were the chemical interactions between the alginate and the mineral phase. This strategic approach revealed the biologically controlled CaCO{sub 3} mineralization within calcium alginate hydrogels via the selective nucleation and the confined crystallization of CaCO{sub 3}. The results presented here could contribute to the understanding of the mineralization process in hydrogel systems. -- Graphical abstract: Schematic illustration of the growth of calcite aggregates with different morphologies obtained from (a) Low G alginate gels and (b) High G alginate gels. Display Omitted highlights: > We use a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system to understand the mediating function of alginate on the crystallization of CaCO{sub 3} crystals. > The crystal size, morphology and crystal surface roughness are influenced by the length of G blocks in alginate. There are chemical interactions between the alginate and the mineral phase. > We propose a potential mechanism of CaCO{sub 3} crystallization within High G and Low G calcium alginate hydrogel.

  17. Chondrogenesis of human bone marrow mesenchymal stromal cells in highly porous alginate-foams supplemented with chondroitin sulfate.

    PubMed

    Huang, Zhao; Nooeaid, Patcharakamon; Kohl, Benjamin; Roether, Judith A; Schubert, Dirk W; Meier, Carola; Boccaccini, Aldo R; Godkin, Owen; Ertel, Wolfgang; Arens, Stephan; Schulze-Tanzil, Gundula

    2015-05-01

    To overcome the limited intrinsic cartilage repair, autologous chondrocyte or bone-marrow-derived mesenchymal stromal cell (BM-MSC) was implanted into cartilage defects. For this purpose suitable biocompatible scaffolds are needed to provide cell retention, chondrogenesis and initial mechanical stability. The present study should indicate whether a recently developed highly porous alginate (Alg) foam scaffold supplemented with chondroitin sulfate (CS) allows the attachment, survival and chondrogenesis of BM-MSCs and articular chondrocytes. The foams were prepared using a freeze-drying method; some of them were supplemented with CS and subsequently characterized for porosity, biodegradation and mechanical profile. BM-MSCs were cultured for 1-2 weeks on the scaffold either under chondrogenic or maintenance conditions. Cell vitality assays, histology, glycosaminoglycan (sGAG) assay, and type II and I collagen immunolabelings were performed to monitor cell growth and extracellular matrix (ECM) synthesis in the scaffolds. Scaffolds had a high porosity ~93-95% with a mean pore sizes of 237±48 μm (Alg) and 197±61 μm (Alg/CS). Incorporation of CS increased mechanical strength of the foams providing gradually CS release over 7 days. Most of the cells survived in the scaffolds. BM-MSCs and articular chondrocytes formed rounded clusters within the scaffold pores. The BM-MSCs, irrespective of whether cultured under non/chondrogenic conditions and chondrocytes produced an ECM containing sGAGs, and types II and I collagen. Total collagen and sGAG contents were higher in differentiated BM-MSC cultures supplemented with CS than in CS-free foams after 14 days. The cell cluster formation induced by the scaffolds might stimulate chondrogenesis via initial intense cell-cell contacts.

  18. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... prepared by the neutralization of purified alginic acid with appropriate pH control agents. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 18, which is incorporated... food Maximum level of use in food (as served) (percent) Functional use Confections, frostings, §...

  19. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...: Category of food Maximum level of use in food (as served) (percent) Functional use Confections, frostings... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ammonium alginate. 184.1133 Section 184.1133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  20. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...: Category of food Maximum level of use in food (as served) (percent) Functional use Confections, frostings... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium alginate. 184.1133 Section 184.1133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  1. Structural properties of scaffolds: Crucial parameters towards stem cells differentiation

    PubMed Central

    Ghasemi-Mobarakeh, Laleh; Prabhakaran, Molamma P; Tian, Lingling; Shamirzaei-Jeshvaghani, Elham; Dehghani, Leila; Ramakrishna, Seeram

    2015-01-01

    Tissue engineering is a multidisciplinary field that applies the principles of engineering and life-sciences for regeneration of damaged tissues. Stem cells have attracted much interest in tissue engineering as a cell source due to their ability to proliferate in an undifferentiated state for prolonged time and capability of differentiating to different cell types after induction. Scaffolds play an important role in tissue engineering as a substrate that can mimic the native extracellular matrix and the properties of scaffolds have been shown to affect the cell behavior such as the cell attachment, proliferation and differentiation. Here, we focus on the recent reports that investigated the various aspects of scaffolds including the materials used for scaffold fabrication, surface modification of scaffolds, topography and mechanical properties of scaffolds towards stem cells differentiation effect. We will present a more detailed overview on the effect of mechanical properties of scaffolds on stem cells fate. PMID:26029344

  2. Scaffold devices for rotator cuff repair.

    PubMed

    Ricchetti, Eric T; Aurora, Amit; Iannotti, Joseph P; Derwin, Kathleen A

    2012-02-01

    Rotator cuff tears affect 40% or more of those aged older than 60 years, and repair failure rates of 20% to 70% remain a significant clinical challenge. Hence, there is a need for repair strategies that can augment the repair by mechanically reinforcing it, while at the same time biologically enhancing the intrinsic healing potential of the tendon. Tissue engineering strategies to improve rotator cuff repair healing include the use of scaffolds, growth factors, and cell seeding, or a combination of these approaches. Currently, scaffolds derived from mammalian extracellular matrix, synthetic polymers, and a combination thereof, have been cleared by the U.S. Food and Drug Administration and are marketed as medical devices for rotator cuff repair in humans. Despite the growing clinical use of scaffold devices for rotator cuff repair, there are numerous questions related to their indication, surgical application, safety, mechanism of action, and efficacy that remain to be clarified or addressed. This article reviews the current basic science and clinical understanding of commercially available synthetic and extracellular matrix scaffolds for rotator cuff repair. Our review will emphasize the host response and scaffold remodeling, mechanical and suture-retention properties, and preclinical and clinical studies on the use of these scaffolds for rotator cuff repair. We will discuss the implications of these data on the future directions for use of these scaffolds in tendon repair procedures.

  3. HAp granules encapsulated oxidized alginate-gelatin-biphasic calcium phosphate hydrogel for bone regeneration.

    PubMed

    Sarker, Avik; Amirian, Jhaleh; Min, Young Ki; Lee, Byong Taek

    2015-11-01

    Bone repair in the critical size defect zone using 3D hydrogel scaffold is still a challenge in tissue engineering field. A novel type of hydrogel scaffold combining ceramic and polymer materials, therefore, was fabricated to meet this challenge. In this study, oxidized alginate-gelatin-biphasic calcium phosphate (OxAlg-Gel-BCP) and spherical hydroxyapatite (HAp) granules encapsulated OxAlg-Gel-BCP hydrogel complex were fabricated using freeze-drying method. Detailed morphological and material characterizations of OxAlg-Gel-BCP hydrogel (OGB00), 25wt% and 35wt% granules encapsulated hydrogel (OGB25 and OGB35) were carried out for micro-structure, porosity, chemical constituents, and compressive stress analysis. Cell viability, cell attachment, proliferation and differentiation behavior of rat bone marrow-derived stem cell (BMSC) on OGB00, OGB25 and OGB35 scaffolds were confirmed by MTT assay, Live-Dead assay, and confocal imaging in vitro experiments. Finally, OGB00 and OGB25 hydrogel scaffolds were implanted in the critical size defect of rabbit femoral chondyle for 4 and 8 weeks. The micro-CT analysis and histological studies conducted by H&E and Masson's trichrome demonstrated that a significantly higher (***p<0.001) and earlier bone formation happened in case of 25% HAp granules encapsulated OxAlg-Gel-BCP hydrogel than in OxAlg-Gel-BCP complex alone. All results taken together, HAp granules encapsulated OxAlg-Gel-BCP system can be a promising 3D hydrogel scaffold for the healing of a critical bone defect.

  4. Raman probing of molecular interactions of alginate biopolymers with cells

    NASA Astrophysics Data System (ADS)

    Chourpa, Igor; Carpentier, Philippe; Maingault, Philippe; Fetissoff, Franck; Dubois, Pierre

    2000-05-01

    The biological polymers extracted from brown algae, alginates, are novel materials in biotechnology and biomedicine. Their ability to form viscous gels is used to immobilize or encapsulate yeast, enzymes, living cells and drugs. Calcium-alginate fibers are extensively used in wound dressings since exhibit antihaemostatic and healing properties. The problem with alginate-made dressings in surgery is their slow biodegradability: if entrapped within tissues, they can induce a local cellular recruitment with an inflammatory response contemporaneous to the resorption phase. In part, this problem is a consequence of poor solubility of the calcium alginates in water. Although calcium alginate fibers can exchange calcium ions with sodium ions from the wound exudate to create a calcium/sodium alginate fibers, the residual alginates are thought to be not totally degradable in vivo. Rapid and non- destructive characterization of series of the crude alginates and calcium alginate fibers has been performed using Raman spectroscopy with near IR excitation. Study of structural organization of the polymeric chains within calcium alginate fibers have been previously reported as made by confocal Raman multispectral imaging (CRMSI) in visible. Here, the Raman approach has been used to monitor the ion exchange reactions for different types of alginates and their salts in vitro. For in vivo evaluation, histological sections of alginate-treated rat tissue have been analyzed by light microscopy and CRMSI. The in vitro Raman modeling and the histochemical mapping were a necessary precursor for application of the Raman microprobe to follow in a non-invasive way the alginate-cell molecular interactions in rat tissue.

  5. Chitin scaffolds in tissue engineering.

    PubMed

    Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V; Furuike, Tetsuya; Tamura, Hiroshi

    2011-01-01

    Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine.

  6. Chitin Scaffolds in Tissue Engineering

    PubMed Central

    Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V.; Furuike, Tetsuya; Tamura, Hiroshi

    2011-01-01

    Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine. PMID:21673928

  7. Sterilization techniques for biodegradable scaffolds in tissue engineering applications

    PubMed Central

    Dai, Zheng; Ronholm, Jennifer; Tian, Yiping; Sethi, Benu; Cao, Xudong

    2016-01-01

    Biodegradable scaffolds have been extensively studied due to their wide applications in biomaterials and tissue engineering. However, infections associated with in vivo use of these scaffolds by different microbiological contaminants remain to be a significant challenge. This review focuses on different sterilization techniques including heat, chemical, irradiation, and other novel sterilization techniques for various biodegradable scaffolds. Comparisons of these techniques, including their sterilization mechanisms, post-sterilization effects, and sterilization efficiencies, are discussed. PMID:27247758

  8. Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization

    PubMed Central

    Takahashi, Mami; Tanaka, Reiji; Miyake, Hideo; Shibata, Toshiyuki; Chow, Seinen; Kuroda, Kouichi; Ueda, Mitsuyoshi; Takeyama, Haruko

    2016-01-01

    Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a primary alginate degradation pathway with only single homologs of an endo- and exo-type alginate lyase, AlyFRA and AlyFRB, which is uncommon among such bacteria. Subsequent functional analysis showed that both enzymes were extremely efficient to depolymerize alginate suggesting evolutionary interests in the acquirement of these enzymes. The exo-type alginate lyase, AlyFRB in particular could depolymerize alginate without producing intermediate products making it a highly efficient enzyme for the production of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Based on our findings, we believe that the discovery of Falsirhodobacter sp. alg1 and its alginolytic genes hints at the potentiality of a more diverse and unique population of alginate-degrading bacteria. PMID:27176711

  9. Enhancement of cell viability by fabrication of macroscopic 3D hydrogel scaffolds using an innovative cell-dispensing technique supplemented by preosteoblast-laden micro-beads.

    PubMed

    Lee, Hyeongjin; Ahn, Seunghyun; Chun, Wook; Kim, Geunhyung

    2014-04-15

    We propose a new cell-encapsulated dispensing method consisting of hydrogel struts, embedded with cell-laden micro-beads. To develop the scaffolds, we accommodated a three-axis robot dispensing system and aerosol spraying of a cross-linking agent to effect tentative surface gelation of hydrogel alginate struts. To show the feasibility of the method, we used pre-osteoblast (MC3T3-E1) cells. Using this technique, we obtained a reasonable cell viability (>90% after several culture periods) relative to that of a scaffold onto which cells were dispensed in the conventional manner, and successfully fabricated a realistic macroscopic pore-size in a controlled manner with 100% pore-interconnected 3D alginate hydrogel scaffolds of 20 mm × 20 mm × 6 mm.

  10. Antibacterial Performance of Alginic Acid Coating on Polyethylene Film

    PubMed Central

    Karbassi, Elika; Asadinezhad, Ahmad; Lehocký, Marian; Humpolíček, Petr; Vesel, Alenka; Novák, Igor; Sáha, Petr

    2014-01-01

    Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance. PMID:25196604

  11. Antibacterial performance of alginic acid coating on polyethylene film.

    PubMed

    Karbassi, Elika; Asadinezhad, Ahmad; Lehocký, Marian; Humpolíček, Petr; Vesel, Alenka; Novák, Igor; Sáha, Petr

    2014-01-01

    Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance. PMID:25196604

  12. Contamination level of alginate impressions arriving at a dental laboratory.

    PubMed

    Sofou, A; Larsen, T; Fiehn, N-E; Owall, B

    2002-09-01

    The contamination level of alginate impressions delivered to a large dental laboratory in Sweden was determined. One hundred and seven consecutive alginate impressions were included during 7 days. Samples were taken and transferred into sterile physiological saline and analysed microbiologically for colony-forming units (cfu) as well as nonhemolytic, alpha-hemolytic, and beta-hemolytic colonies. After sampling, the clinics were contacted and asked to fill in simple questionnaires about their routines of disinfecting impressions. The questionnaire study revealed that about half of the clinics had some kind of disinfection routine, while the others rinsed in running water only. Seventy-two percent of the impressions yielded growth of bacteria, with a median number of 1.3x10(2) cfu. Thirteen per cent of the samples yielded >10(3) cfu, with a maximum number of 3.4x10(4) cfu. The majority of isolates were non- and alpha-hemolytic bacteria. Growth was recorded in 61.3% of disinfected impressions, and the numbers of bacteria in disinfected and nondisinfected impressions were similar. These findings raise the question of whether impressions need to be disinfected or if proper handling and hygienic procedures are sufficient to block the possible route of infection. PMID:12271349

  13. Contamination level of alginate impressions arriving at a dental laboratory.

    PubMed

    Sofou, A; Larsen, T; Fiehn, N-E; Owall, B

    2002-09-01

    The contamination level of alginate impressions delivered to a large dental laboratory in Sweden was determined. One hundred and seven consecutive alginate impressions were included during 7 days. Samples were taken and transferred into sterile physiological saline and analysed microbiologically for colony-forming units (cfu) as well as nonhemolytic, alpha-hemolytic, and beta-hemolytic colonies. After sampling, the clinics were contacted and asked to fill in simple questionnaires about their routines of disinfecting impressions. The questionnaire study revealed that about half of the clinics had some kind of disinfection routine, while the others rinsed in running water only. Seventy-two percent of the impressions yielded growth of bacteria, with a median number of 1.3x10(2) cfu. Thirteen per cent of the samples yielded >10(3) cfu, with a maximum number of 3.4x10(4) cfu. The majority of isolates were non- and alpha-hemolytic bacteria. Growth was recorded in 61.3% of disinfected impressions, and the numbers of bacteria in disinfected and nondisinfected impressions were similar. These findings raise the question of whether impressions need to be disinfected or if proper handling and hygienic procedures are sufficient to block the possible route of infection.

  14. Development of a Multi-Functional Biopolymer Scaffold for Neural Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Francis, Nicola Louise

    Spinal cord injury (SCI) affects approximately 270,000 people in the U.S., with approximately 12,000 new cases occurring every year. Several strategies have been investigated to enhance axonal regeneration after SCI, however, the resulting growth can be random and disorganized. Bioengineered scaffolds provide a physical substrate for the guidance of regenerating axons towards their targets, and can be produced by freeze casting. This technique involves the controlled directional solidification of an aqueous solution or suspension, resulting in a linearly aligned porous structure caused by ice templating. In this thesis, freeze casting was used to create novel porous chitosan-alginate (C/A) scaffolds with longitudinally aligned channels and a compressive modulus (5.08 ± 0.61 kPa) comparable to that of native spinal cord tissue. These C/A scaffolds supported the viability, attachment, and directionally oriented growth of chick dorsal root ganglia (DRG) neurites in vitro, with surface adsorptions of polycations and laminin promoting significantly longer neurite growth than the uncoated scaffolds (p<0.001). In order to integrate therapeutic biomolecules within the scaffolds for sustained release, alginate and chitosan microcapsules produced by spray drying were used to encapsulate brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), and the enzyme chondroitinase ABC (chABC) prior to scaffold incorporation. BDNF and NT-3 were released from the C/A scaffolds in a sustained manner for 8 weeks in vitro, while chABC was released for up to 35 days. However, up to 85% of biomolecules emained entrapped within the scaffold walls, due to limitation of diffusion by the scaffold wall mesh size. Release of bioactive chABC and neurotrophins from the multifunctional scaffolds promoted the growth of DRG neurites through an in vitro barrier of chondroitin sulfate proteoglycans, a main inhibitory component of the growth-inhibiting glial scar in the injured spinal cord

  15. Use of chitosan-alginate as alternative pelletization aid to microcrystalline cellulose in extrusion/spheronization.

    PubMed

    Charoenthai, Nattawut; Kleinebudde, Peter; Puttipipatkhachorn, Satit

    2007-09-01

    Two types of different molecular weight chitosan were investigated as a pelletization aid in extrusion/spheronization using water as granulation liquid. Spherical pellets with a maximum fraction of 60% w/w chitosan could be produced when 1.25-2.5% w/w sodium alginate was included in the formulations with no microcrystalline cellulose (MCC). Chitosan with lower molecular weight of 190 kDa showed a better pellet forming property. The pellets obtained had acceptable physical characteristics and a fast drug release. The results from Fourier transform infrared spectroscopy, differential scanning calorimetry and (13)C CP-MAS nuclear magnetic resonance spectroscopy confirmed the formation of polyelectrolyte complex (PEC) between chitosan and sodium alginate, which might be a reason for successful pelletization by extrusion/spheronization. Moreover, the presence of PEC might influence the physical characteristics and dissolution behavior of chitosan-alginate pellets. The results indicated an achievement in production of pellets by extrusion/spheronization without using MCC. Moreover, chitosan combined with sodium alginate could be used as a promising alternative pelletization aid to MCC in extrusion/spheronization. PMID:17286294

  16. The secretome of alginate-encapsulated limbal epithelial stem cells modulates corneal epithelial cell proliferation.

    PubMed

    Wright, Bernice; Hopkinson, Andrew; Leyland, Martin; Connon, Che J

    2013-01-01

    Limbal epithelial stem cells may ameliorate limbal stem cell deficiency through secretion of therapeutic proteins, delivered to the cornea in a controlled manner using hydrogels. In the present study the secretome of alginate-encapsulated limbal epithelial stem cells is investigated. Conditioned medium was generated from limbal epithelial stem cells encapsulated in 1.2% (w/v) calcium alginate gels. Conditioned medium proteins separated by 1-D gel electrophoresis were visualized by silver staining. Proteins of interest including secreted protein acidic and rich in cysteine, profilin-1, and galectin-1 were identified by immunoblotting. The effect of conditioned medium (from alginate-encapsulated limbal epithelial stem cells) on corneal epithelial cell proliferation was quantified and shown to significantly inhibit (P≤0.05) their growth. As secreted protein acidic and rich in cysteine was previously reported to attenuate proliferation of epithelial cells, this protein may be responsible, at least in part, for inhibition of corneal epithelial cell proliferation. We conclude that limbal epithelial stem cells encapsulated in alginate gels may regulate corneal epithelialisation through secretion of inhibitory proteins.

  17. A review: fabrication of porous polyurethane scaffolds.

    PubMed

    Janik, H; Marzec, M

    2015-03-01

    The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages.

  18. ASTM International Workshop on Standards & Measurements for Tissue Engineering Scaffolds

    PubMed Central

    Simon, Carl G.; Yaszemski, Michael J.; Ratcliffe, Anthony; Tomlins, Paul; Luginbuehl, Reto; Tesk, John A.

    2016-01-01

    The “Workshop on Standards & Measurements for Tissue Engineering Scaffolds” was held on May 21, 2013 in Indianapolis, IN and was sponsored by the ASTM International (ASTM). The purpose of the workshop was to identify the highest priority items for future standards work for scaffolds used in the development and manufacture of tissue engineered medical products (TEMPs). Eighteen speakers and 78 attendees met to assess current scaffold standards and to prioritize needs for future standards. A key finding was that the ASTM TEMPs subcommittees (F04.41-46) have many active “guide” documents for educational purposes, but that few standard “test methods” or “practices” have been published. Overwhelmingly, the most clearly identified need was standards for measuring the structure of scaffolds, followed by standards for biological characterization, including in vitro testing, animal models and cell-material interactions. The third most pressing need was to develop standards for assessing the mechanical properties of scaffolds. Additional needs included standards for assessing scaffold degradation, clinical outcomes with scaffolds, effects of sterilization on scaffolds, scaffold composition and drug release from scaffolds. Discussions also highlighted the need for additional scaffold reference materials and the need to use them for measurement traceability. Finally, dialogue emphasized the needs to promote the use of standards in scaffold fabrication, characterization, and commercialization and to assess the use and impact of standards in the TEMPs community. Many scaffold standard needs have been identified and focus should now turn to generating these standards to support the use of scaffolds in TEMPs. PMID:25220952

  19. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate.

  20. An Alginate-based Hybrid System for Growth Factor Delivery in the Functional Repair of Large Bone Defects

    PubMed Central

    Kolambkar, Yash M.; Dupont, Kenneth M.; Boerckel, Joel D.; Huebsch, Nathaniel; Mooney, David J.; Hutmacher, Dietmar W.

    2010-01-01

    The treatment of challenging fractures and large osseous defects presents a formidable problem for orthopaedic surgeons. Tissue engineering/regenerative medicine approaches seek to solve this problem by delivering osteogenic signals within scaffolding biomaterials. In this study, we introduce a hybrid growth factor delivery system that consists of an electrospun nanofiber mesh tube for guiding bone regeneration combined with peptide-modified alginate hydrogel injected inside the tube for sustained growth factor release. We tested the ability of this system to deliver recombinant bone morphogenetic protein-2 (rhBMP-2) for the repair of critically-sized segmental bone defects in a rat model. Longitudinal μ-CT analysis and torsional testing provided quantitative assessment of bone regeneration. Our results indicate that the hybrid delivery system resulted in consistent bony bridging of the challenging bone defects. However, in the absence of rhBMP-2, the use of nanofiber mesh tube and alginate did not result in substantial bone formation. Perforations in the nanofiber mesh accelerated the rhBMP-2 mediated bone repair, and resulted in functional restoration of the regenerated bone. μ-CT based angiography indicated that perforations did not significantly affect the revascularization of defects, suggesting that some other interaction with the tissue surrounding the defect such as improved infiltration of osteoprogenitor cells contributed to the observed differences in repair. Overall, our results indicate that the hybrid alginate/nanofiber mesh system is a promising growth factor delivery strategy for the repair of challenging bone injuries. PMID:20864165

  1. Genipin-Crosslinked Chitosan Gels and Scaffolds for Tissue Engineering and Regeneration of Cartilage and Bone

    PubMed Central

    Muzzarelli, Riccardo A. A.; El Mehtedi, Mohamad; Bottegoni, Carlo; Aquili, Alberto; Gigante, Antonio

    2015-01-01

    The present review article intends to direct attention to the technological advances made since 2009 in the area of genipin-crosslinked chitosan (GEN-chitosan) hydrogels. After a concise introduction on the well recognized characteristics of medical grade chitosan and food grade genipin, the properties of GEN-chitosan obtained with a safe, spontaneous and irreversible chemical reaction, and the quality assessment of the gels are reviewed. The antibacterial activity of GEN-chitosan has been well assessed in the treatment of gastric infections supported by Helicobacter pylori. Therapies based on chitosan alginate crosslinked with genipin include stem cell transplantation, and development of contraction free biomaterials suitable for cartilage engineering. Collagen, gelatin and other proteins have been associated to said hydrogels in view of the regeneration of the cartilage. Viability and proliferation of fibroblasts were impressively enhanced upon addition of poly-l-lysine. The modulation of the osteocytes has been achieved in various ways by applying advanced technologies such as 3D-plotting and electrospinning of biomimetic scaffolds, with optional addition of nano hydroxyapatite to the formulations. A wealth of biotechnological advances and know-how has permitted reaching outstanding results in crucial areas such as cranio-facial surgery, orthopedics and dentistry. It is mandatory to use scaffolds fully characterized in terms of porosity, pore size, swelling, wettability, compressive strength, and degree of acetylation, if the osteogenic differentiation of human mesenchymal stem cells is sought: in fact, the novel characteristics imparted by GEN-chitosan must be simultaneously of physico-chemical and cytological nature. Owing to their high standard, the scientific publications dated 2010–2015 have met the expectations of an interdisciplinary audience. PMID:26690453

  2. Genipin-Crosslinked Chitosan Gels and Scaffolds for Tissue Engineering and Regeneration of Cartilage and Bone.

    PubMed

    Muzzarelli, Riccardo A A; El Mehtedi, Mohamad; Bottegoni, Carlo; Aquili, Alberto; Gigante, Antonio

    2015-12-11

    The present review article intends to direct attention to the technological advances made since 2009 in the area of genipin-crosslinked chitosan (GEN-chitosan) hydrogels. After a concise introduction on the well recognized characteristics of medical grade chitosan and food grade genipin, the properties of GEN-chitosan obtained with a safe, spontaneous and irreversible chemical reaction, and the quality assessment of the gels are reviewed. The antibacterial activity of GEN-chitosan has been well assessed in the treatment of gastric infections supported by Helicobacter pylori. Therapies based on chitosan alginate crosslinked with genipin include stem cell transplantation, and development of contraction free biomaterials suitable for cartilage engineering. Collagen, gelatin and other proteins have been associated to said hydrogels in view of the regeneration of the cartilage. Viability and proliferation of fibroblasts were impressively enhanced upon addition of poly-l-lysine. The modulation of the osteocytes has been achieved in various ways by applying advanced technologies such as 3D-plotting and electrospinning of biomimetic scaffolds, with optional addition of nano hydroxyapatite to the formulations. A wealth of biotechnological advances and know-how has permitted reaching outstanding results in crucial areas such as cranio-facial surgery, orthopedics and dentistry. It is mandatory to use scaffolds fully characterized in terms of porosity, pore size, swelling, wettability, compressive strength, and degree of acetylation, if the osteogenic differentiation of human mesenchymal stem cells is sought: in fact, the novel characteristics imparted by GEN-chitosan must be simultaneously of physico-chemical and cytological nature. Owing to their high standard, the scientific publications dated 2010-2015 have met the expectations of an interdisciplinary audience.

  3. Redox-responsive alginate microsphere containing cystamine.

    PubMed

    Kwon, Kyeongnan; Kim, Jin-Chul

    2016-10-01

    Redox-responsive microspheres were prepared by solidifying the alginate- and cystamine-containing water droplets of O/W emulsion using calcium ion. Emulsions were prepared using alginate/cystamine mixture solution whose the carboxylic group/the amino group molar ratio was 1:1, 1:2, and 1:3, and whose the total concentration was kept to 2% (w/v). The microspheres on Scanning electron microscopy photographs were almost spherical and they were less than 1 μm in diameter. According to the energy-dispersive X-ray spectroscopy, the sulfur content of the microspheres was found to be 6.1, 11.4, and 14.8% (w/w), respectively, not markedly different from the calculated content. The release degree of blue dextran loaded in the microspheres was higher as the cystamine content was higher. Microspheres released almost the same amount of dye regardless of dithiothreitol (DTT, a reducing agent) concentration when the cystamine content was relatively low (e.g. 14.5% (w/w)), whereas they released dye in DTT concentration-dependent manner when the cystamine content was relatively high (e.g. 27.0 and 35.1% (w/w)). The light scattering intensity of alginate/cystamine mixture solution was stronger at a larger amount of cystamine, indicating that cystamine could cross-link alginate chains. The light scattering intensity decreased with increasing DTT concentration, possibly because of the breakdown of the disulfide bond of cystamine. The breakdown of the disulfide bond could account for why the DTT concentration-dependent release of dye loaded in the microspheres was observed. PMID:27484719

  4. Development of silver sulfadiazine loaded bacterial cellulose/sodium alginate composite films with enhanced antibacterial property.

    PubMed

    Shao, Wei; Liu, Hui; Liu, Xiufeng; Wang, Shuxia; Wu, Jimin; Zhang, Rui; Min, Huihua; Huang, Min

    2015-11-01

    Sodium alginate (SA) and bacterial cellulose (BC) are widely used in many applications such as scaffolds and wound dressings due to its biocompatibility. Silver sulfadiazine (AgSD) is a topical antibacterial agents used as a topical cream on burns. In the study, novel BC/SA-AgSD composites were prepared and characterized by SEM, FTIR and TG analyses. These results indicate AgSD successfully impregnated into BC/SA matrix. The swelling behaviors in different pH were studied and the results showed pH-responsive swelling behaviors. The antibacterial performances of BC/SA-AgSD composites were evaluated with Escherichia coli, Staphylococcus aureus and Candida albicans. Moreover, the cytotoxicity of BC/SA-AgSD composites was performed on HEK 293 cells. The experimental results showed BC/SA-AgSD composites have excellent antibacterial activities and good biocompatibility, thus confirming its utility as potential wound dressings.

  5. Neuralization of mouse embryonic stem cells in alginate hydrogels under retinoic acid and SAG treatment.

    PubMed

    Delivopoulos, Evangelos; Shakesheff, Kevin M; Peto, Heather

    2015-08-01

    This paper examines the differentiation of a mouse embryonic stem cell line (CGR8) into neurons, under retinoic acid (RA) and smoothened agonist (SAG) treatment. When stem cells underwent through an embryoid body (EB) formation stage, dissociation and seeding on glass coverslips, immunofluorescent labelling for neuronal markers (Nestin, b-Tubulin III, MAP2) revealed the presence of both immature neural progenitors and mature neurons. Undifferentiated CGR8 were also encapsulated in tubular, alginate-gelatin hydrogels and incubated in differentiation media containing retinoic acid (RA) and smoothened agonist (SAG). Cryo-sections of the hydrogel tubes were positive for Nestin, Pax6 and b-Tubulin III, verifying the presence of neurons and neural progenitors. Provided neural induction can be more precisely directed in the tubular hydrogels, these scaffolds will become a powerful model of neural tube development in embryos and will highlight potential strategies for spinal cord regeneration. PMID:26737053

  6. 3D Printing of Scaffolds for Tissue Regeneration Applications

    PubMed Central

    Do, Anh-Vu; Khorsand, Behnoush; Geary, Sean M.; Salem, Aliasger K.

    2015-01-01

    The current need for organ and tissue replacement, repair and regeneration for patients is continually growing such that supply is not meeting the high demand primarily due to a paucity of donors as well as biocompatibility issues that lead to immune rejection of the transplant. In an effort to overcome these drawbacks, scientists working in the field of tissue engineering and regenerative medicine have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired a growing interest in 3D printing as a mode for generating scaffolds. Utilizing three-dimensional printing (3DP) technologies, ECM-like scaffolds can be produced with a high degree of complexity and precision, where fine details can be included at a micron level. In this review, we discuss the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering. A hybrid approach, employing both natural and synthetic materials, as well as multiple printing processes may be the key to yielding an ECM-like scaffold with high mechanical strength, porosity, interconnectivity, biocompatibility, biodegradability, and high processability. Creating such biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation. PMID:26097108

  7. Alginate and DNA Gels Are Suitable Delivery Systems for Diabetic Wound Healing.

    PubMed

    Tellechea, Ana; Silva, Eduardo A; Min, Jianghong; Leal, Ermelindo C; Auster, Michael E; Pradhan-Nabzdyk, Leena; Shih, William; Mooney, David J; Veves, Aristidis

    2015-06-01

    Diabetic foot ulcers (DFU) represent a severe health problem and an unmet clinical challenge. In this study, we tested the efficacy of novel biomaterials in improving wound healing in mouse models of diabetes mellitus (DM). The biomaterials are composed of alginate- and deoxyribonucleic acid (DNA)-based gels that allow incorporation of effector cells, such as outgrowth endothelial cells (OEC), and provide sustained release of bioactive factors, such as neuropeptides and growth factors, which have been previously validated in experimental models of DM wound healing or hind limb ischemia. We tested these biomaterials in mice and demonstrate that they are biocompatible and can be injected into the wound margins without major adverse effects. In addition, we show that the combination of OEC and the neuropeptide Substance P has a better healing outcome than the delivery of OEC alone, while subtherapeutic doses of vascular endothelial growth factor (VEGF) are required for the transplanted cells to exert their beneficial effects in wound healing. In summary, alginate and DNA scaffolds could serve as potential delivery systems for the next-generation DFU therapies.

  8. Novel porous graphene oxide and hydroxyapatite nanosheets-reinforced sodium alginate hybrid nanocomposites for medical applications

    SciTech Connect

    Xiong, Guangyao; Luo, Honglin; Zuo, Guifu; Ren, Kaijing; Wan, Yizao

    2015-09-15

    Graphene oxide (GO) and hydroxyapatite (HAp) are frequently used as reinforcements in polymers to improve mechanical and biological properties. In this work, novel porous hybrid nanocomposites consisting of GO, HAp, and sodium alginate (SA) have been prepared by facile solution mixing and freeze drying in an attempt to obtain a scaffold with desirable mechanical and biological properties. The as-prepared porous GO/HAp/SA hybrid nanocomposites were characterized by SEM, XRD, FTIR, TGA, and mechanical testing. In addition, preliminary cell behavior was assessed by CCK8 assay. It is found that the GO/HAp/SA nanocomposites show improved compressive strength and modulus over neat SA and HAp/SA nanocomposites. CCK8 results reveal that the GO/HAp/SA nanocomposites show enhanced cell proliferation over neat SA and GO/SA nanocomposite. It has been demonstrated that GO/HAp20/SA holds promise in bone tissue engineering. - Graphical abstract: Display Omitted - Highlights: • Graphene oxide (GO), hydroxyapatite (HAp), and alginate (SA) nanocomposites were fabricated. • The novel porous composites were prepared by solution mixture and freeze drying. • The GO/HAp/SA had porous structure with porosity > 85% and pore size > 150 μm. • The GO/HAp/SA exhibited improved mechanical properties over HAp/SA counterparts. • The GO/HAp/SA showed enhanced cell proliferation over GO/SA counterparts.

  9. Scaffold Design for Bone Regeneration

    PubMed Central

    Polo-Corrales, Liliana; Latorre-Esteves, Magda; Ramirez-Vick, Jaime E.

    2014-01-01

    The use of bone grafts is the standard to treat skeletal fractures, or to replace and regenerate lost bone, as demonstrated by the large number of bone graft procedures performed worldwide. The most common of these is the autograft, however, its use can lead to complications such as pain, infection, scarring, blood loss, and donor-site morbidity. The alternative is allografts, but they lack the osteoactive capacity of autografts and carry the risk of carrying infectious agents or immune rejection. Other approaches, such as the bone graft substitutes, have focused on improving the efficacy of bone grafts or other scaffolds by incorporating bone progenitor cells and growth factors to stimulate cells. An ideal bone graft or scaffold should be made of biomaterials that imitate the structure and properties of natural bone ECM, include osteoprogenitor cells and provide all the necessary environmental cues found in natural bone. However, creating living tissue constructs that are structurally, functionally and mechanically comparable to the natural bone has been a challenge so far. This focus of this review is on the evolution of these scaffolds as bone graft substitutes in the process of recreating the bone tissue microenvironment, including biochemical and biophysical cues. PMID:24730250

  10. ASTM international workshop on standards and measurements for tissue engineering scaffolds.

    PubMed

    Simon, Carl G; Yaszemski, Michael J; Ratcliffe, Anthony; Tomlins, Paul; Luginbuehl, Reto; Tesk, John A

    2015-07-01

    The "Workshop on Standards & Measurements for Tissue Engineering Scaffolds" was held on May 21, 2013 in Indianapolis, IN, and was sponsored by the ASTM International (ASTM). The purpose of the workshop was to identify the highest priority items for future standards work for scaffolds used in the development and manufacture of tissue engineered medical products (TEMPs). Eighteen speakers and 78 attendees met to assess current scaffold standards and to prioritize needs for future standards. A key finding was that the ASTM TEMPs subcommittees (F04.41-46) have many active "guide" documents for educational purposes, but few standard "test methods" or "practices." Overwhelmingly, the most clearly identified need was standards for measuring the structure of scaffolds, followed by standards for biological characterization, including in vitro testing, animal models and cell-material interactions. The third most pressing need was to develop standards for assessing the mechanical properties of scaffolds. Additional needs included standards for assessing scaffold degradation, clinical outcomes with scaffolds, effects of sterilization on scaffolds, scaffold composition, and drug release from scaffolds. Discussions highlighted the need for additional scaffold reference materials and the need to use them for measurement traceability. Workshop participants emphasized the need to promote the use of standards in scaffold fabrication, characterization, and commercialization. Finally, participants noted that standards would be more broadly accepted if their impact in the TEMPs community could be quantified. Many scaffold standard needs have been identified and focus is turning to generating these standards to support the use of scaffolds in TEMPs.

  11. Imaging contrast effects in alginate microbeads containing trapped emulsion droplets.

    PubMed

    Hester-Reilly, Holly J; Shapley, Nina C

    2007-09-01

    This study focuses on spherical microparticles made of cross-linked alginate gel and microcapsules composed of an oil-in-water emulsion where the continuous aqueous phase is cross-linked into an alginate gel matrix. We have investigated the use of these easily manufactured microbeads as contrast agents for the study of the flow properties of fluids using nuclear magnetic resonance imaging. Results demonstrate that combined spin-spin (T(2)) relaxation and diffusion contrast in proton NMR imaging can be used to distinguish among rigid polymer particles, plain alginate beads, and alginate emulsion beads. Multi-echo CPMG spin-echo imaging indicates that the average spin-lattice (T(1)) and spin-spin (T(2)) relaxation times of the plain alginate and alginate emulsion beads are comparable. Meanwhile, diffusion-weighted imaging produces sharp contrast between the two types of alginate beads, due to restricted diffusion inside the embedded oil droplets of the alginate emulsion beads. While the signal obtained from most materials is severely attenuated under applied diffusion gradients, the alginate emulsion beads maintain signal strength. The alginate emulsion beads were added to a suspension and imaged in an abrupt, annular expansion flow. The emulsion beads could be clearly distinguished from the surrounding suspending fluid and rigid polystyrene particles, through either T(2) relaxation or diffusion contrast. Such a capability allows future use of the alginate emulsion beads as tracer particles and as one particle type among many in a multimodal suspension where detailed concentration profiles or particle size separation must be quantified during flow. PMID:17600742

  12. Further Development of Scaffolds for Regeneration of Nerves

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeffrey; Tuszynski, Mark

    2009-01-01

    Progress has been made in continuing research on scaffolds for the guided growth of nerves to replace damaged ones. The scaffolds contain pores that are approximately cylindrical and parallel, with nearly uniform widths ranging from tens to hundreds of microns. At the earlier stage of development, experimental scaffolds had been made from agarose hydrogel. Such a scaffold was made in a multistep process in which poly(methyl methacrylate) [PMMA] fibers were used as templates for the pores. The process included placement of a bundle of the PMMA fibers in a tube, filling the interstices in the tube with a hot agarose solution, cooling to turn the solution into a gel, and then immersion in acetone to dissolve the PMMA fibers. The scaffolds were typically limited to about 25 pores per scaffold, square cross sections of no more than about 1.5 by 1.5 mm, and lengths of no more than about 2 mm.

  13. Exact approaches for scaffolding

    PubMed Central

    2015-01-01

    This paper presents new structural and algorithmic results around the scaffolding problem, which occurs prominently in next generation sequencing. The problem can be formalized as an optimization problem on a special graph, the "scaffold graph". We prove that the problem is polynomial if this graph is a tree by providing a dynamic programming algorithm for this case. This algorithm serves as a basis to deduce an exact algorithm for general graphs using a tree decomposition of the input. We explore other structural parameters, proving a linear-size problem kernel with respect to the size of a feedback-edge set on a restricted version of Scaffolding. Finally, we examine some parameters of scaffold graphs, which are based on real-world genomes, revealing that the feedback edge set is significantly smaller than the input size. PMID:26451725

  14. Versatile design of hydrogel-based scaffolds with manipulated pore structure for hard-tissue regeneration.

    PubMed

    Kim, WonJin; Lee, Hyeongjin; Kim, YongBok; Choi, Chang Hyun; Lee, DaeWeon; Hwang, Heon; Kim, GeunHyung

    2016-01-01

    In recent years, a variety of biomimetic hydrogel scaffolds have been used in tissue engineering because hydrogels can provide reasonable soft-tissue-like environmental conditions for various cell responses. However, although hydrogels can provide an outstanding biofunctional platform, their poor mechanical stability and low processability have been obstacles for their usage as biomedical scaffolds. To overcome this limitation, we propose a simple and versatile method using 3D printing supplemented with a low-temperature working plate and coating process to reinforce the mechanical properties and various cellular activities by accommodating the poly(ε-caprolactone) (PCL). To determine the efficiency of the method, we used two typical hydrogels (alginate and collagen), which were deposited in a multi-layer configuration, and PCL as a coating agent. The scaffolds were evaluated in terms of various physical and cellular activities (metabolic activity and osteogenic activity). Throughout the experiments, significant increases in the tensile modulus (>6-fold), cell proliferation (>1.2-fold), and calcium deposition (>1.3-fold) were observed for the hydrogel/PCL scaffolds compared to those for pure hydrogel. Based on the experimental results, we can confirm that the proposed hydrogel scaffold can be a highly promising biomedical scaffold for application in tissue regeneration. PMID:27586518

  15. Cell-laden biphasic scaffolds with anisotropic structure for the regeneration of osteochondral tissue.

    PubMed

    Schütz, Kathleen; Despang, Florian; Lode, Anja; Gelinsky, Michael

    2016-05-01

    Sufficient treatment of chondral and osteochondral defects to restore function of the respective tissue remains challenging in regenerative medicine. Biphasic scaffolds that mimic properties of bone and cartilage are appropriate to regenerate both tissues at the same time. The present study describes the development of biphasic, but monolithic scaffolds based on alginate, which are suitable for embedding of living cells in the chondral part. Scaffolds are fabricated under sterile and cell-compatible conditions according to the principle of diffusion-controlled, directed ionotropic gelation, which leads to the formation of channel-like, parallel aligned pores, running through the whole length of the biphasic constructs. The synthesis process leads to an anisotropic structure, as it is found in many natural tissues. The two different layers of the scaffolds are characterized by different microstructure and mechanical properties which provide a suitable environment for cells to form the respective tissue. Human chondrocytes and human mesenchymal stem cells were embedded within the chondral layer of the biphasic scaffolds during hydrogel formation and their chondrogenic (re)differentiation was successfully induced. Whereas viability of non-induced human mesenchymal stem cells decreased during culture, cell viability of human chondrocytes and chondrogenically induced human mesenchymal stem cells remained high within the scaffolds over the whole culture period of 3 weeks, demonstrating successful fabrication of cell-laden centimetre-scaled constructs for potential application in regenerative treatment of osteochondral defects. Copyright © 2014 John Wiley & Sons, Ltd.

  16. A Controlled Drug-Delivery Experiment Using Alginate Beads

    ERIC Educational Resources Information Center

    Farrell, Stephanie; Vernengo, Jennifer

    2012-01-01

    This paper describes a simple, cost-effective experiment which introduces students to drug delivery and modeling using alginate beads. Students produce calcium alginate beads loaded with drug and measure the rate of release from the beads for systems having different stir rates, geometries, extents of cross-linking, and drug molecular weight.…

  17. Soy Protein Scaffold Biomaterials for Tissue Engineering and Regenerative Medicine

    NASA Astrophysics Data System (ADS)

    Chien, Karen B.

    Developing functional biomaterials using highly processable materials with tailorable physical and bioactive properties is an ongoing challenge in tissue engineering. Soy protein is an abundant, natural resource with potential use for regenerative medicine applications. Preliminary studies show that soy protein can be physically modified and fabricated into various biocompatible constructs. However, optimized soy protein structures for tissue regeneration (i.e. 3D porous scaffolds) have not yet been designed. Furthermore, little work has established the in vivo biocompatibility of implanted soy protein and the benefit of using soy over other proteins including FDA-approved bovine collagen. In this work, freeze-drying and 3D printing fabrication processes were developed using commercially available soy protein to create porous scaffolds that improve cell growth and infiltration compared to other soy biomaterials previously reported. Characterization of scaffold structure, porosity, and mechanical/degradation properties was performed. In addition, the behavior of human mesenchymal stem cells seeded on various designed soy scaffolds was analyzed. Biological characterization of the cell-seeded scaffolds was performed to assess feasibility for use in liver tissue regeneration. The acute and humoral response of soy scaffolds implanted in an in vivo mouse subcutaneous model was also investigated. All fabricated soy scaffolds were modified using thermal, chemical, and enzymatic crosslinking to change properties and cell growth behavior. 3D printing allowed for control of scaffold pore size and geometry. Scaffold structure, porosity, and degradation rate significantly altered the in vivo response. Freeze-dried soy scaffolds had similar biocompatibility as freeze-dried collagen scaffolds of the same protein content. However, the soy scaffolds degraded at a much faster rate, minimizing immunogenicity. Interestingly, subcutaneously implanted soy scaffolds affected blood

  18. Preparation and characterization of alginate and alginate-resistant starch microparticles containing nisin.

    PubMed

    Hosseini, Seyede Marzieh; Hosseini, Hedayat; Mohammadifar, Mohammad Amin; German, J Bruce; Mortazavian, Amir Mohammad; Mohammadi, Abdorreza; Khosravi-Darani, Kianoosh; Shojaee-Aliabadi, Saeedeh; Khaksar, Ramin

    2014-03-15

    Delivery systems with sustained release of nisin have been proposed to improve stability and long-term effectiveness of this bacteriocin in foods. In this study, nisin was encapsulated in alginate (Alg) and alginate-resistant starch (Alg-RS) microparticles and its release was investigated. Studies found that the nisin concentration has significant influence on encapsulation efficiency (EE), loading capacity (LC) and size of both microparticles. Furthermore, encapsulation efficiency and loading capacity values were more increased by the addition of resistant starch to the alginate formulation. The highest encapsulation efficiency was obtained with Alg-RS microparticles prepared using initial nisin to alginate weight ratio of 25% w/w (59.77 ± 2.26%). Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results confirmed the presence of nisin in the microparticles. The in vitro nisin release from these microparticles followed a controlled-release pattern consistent with a Fickian diffusion mechanism. The release rate from Alg-RS microparticles was less than that from the Alg microparticles.

  19. Maximization of volatile fatty acids production from alginate in acidogenesis.

    PubMed

    Pham, Hong Duc; Seon, Jiyun; Lee, Seong Chan; Song, Minkyung; Woo, Hee-Chul

    2013-11-01

    In this study, the response surface methodology (RSM) was applied to determine the optimum fermentative condition of alginate with the respect to the simultaneous effects of alginate concentration and initial pH to maximize the production of total volatile fatty acids (TVFAs) and alcohols. The results showed that the alginate fermentation was significantly affected by initial pH than by alginate concentration and there was no interaction between the two variables. The optimum condition was 6.2g alginate/L and initial pH 7.6 with a maximum TVFAs yield of 37.1%. Acetic acids were the main constituents of the TVFAs mixtures (i.e., 71.9-95.5%), while alcohols (i.e., ethanol, butanol, and propanol) were not detected.

  20. Depolymerization of alginate into a monomeric sugar acid using Alg17C, an exo-oligoalginate lyase cloned from Saccharophagus degradans 2-40.

    PubMed

    Kim, Hee Taek; Chung, Jae Hyuk; Wang, Damao; Lee, Jieun; Woo, Hee Chul; Choi, In-Geol; Kim, Kyoung Heon

    2012-03-01

    Macroalgae are considered to be promising biomass for fuels and chemicals production. To utilize brown macroalgae as biomass, the degradation of alginate, which is the main carbohydrate of brown macroalgae, into monomeric units is a critical prerequisite step. Saccharophagus degradans 2-40 is capable of degrading more than ten different polysaccharides including alginate, and its genome sequence demonstrated that this bacterium contains several putative alginate lyase genes including alg17C. The gene for Alg17C, which is classified into the PL-17 family, was cloned and overexpressed in Escherichia coli. The recombinant Alg17C was found to preferentially act on oligoalginates with degrees of polymerization higher than 2 to produce the alginate monomer, 4-deoxy-L: -erythro-5-hexoseulose uronic acid. The optimal pH and temperature for Alg17C were found to be 6 and 40 °C, respectively. The K (M) and V (max) of Alg17C were 35.2 mg/ml and 41.7 U/mg, respectively. Based on the results of this study, Alg17C could be used as the key enzyme to produce alginate monomers in the process of utilizing alginate for biofuels and chemicals production. PMID:22281843

  1. Engineering functionally graded tissue engineering scaffolds.

    PubMed

    Leong, K F; Chua, C K; Sudarmadji, N; Yeong, W Y

    2008-04-01

    Tissue Engineering (TE) aims to create biological substitutes to repair or replace failing organs or tissues due to trauma or ageing. One of the more promising approaches in TE is to grow cells on biodegradable scaffolds, which act as temporary supports for the cells to attach, proliferate and differentiate; after which the scaffold will degrade, leaving behind a healthy regenerated tissue. Tissues in nature, including human tissues, exhibit gradients across a spatial volume, in which each identifiable layer has specific functions to perform so that the whole tissue/organ can behave normally. Such a gradient is termed a functional gradient. A good TE scaffold should mimic such a gradient, which fulfils the biological and mechanical requirements of the target tissue. Thus, the design and fabrication process of such scaffolds become more complex and the introduction of computer-aided tools will lend themselves well to ease these challenges. This paper reviews the needs and characterization of these functional gradients and the computer-aided systems used to ease the complexity of the scaffold design stage. These include the fabrication techniques capable of building functionally graded scaffolds (FGS) using both conventional and rapid prototyping (RP) techniques. They are able to fabricate both continuous and discrete types of FGS. The challenge in fabricating continuous FGS using RP techniques lies in the development of suitable computer aided systems to facilitate continuous FGS design. What have been missing are the appropriate models that relate the scaffold gradient, e.g. pore size, porosity or material gradient, to the biological and mechanical requirements for the regeneration of the target tissue. The establishment of these relationships will provide the foundation to develop better computer-aided systems to help design a suitable customized FGS.

  2. Laser microstructured biodegradable scaffolds.

    PubMed

    Koroleva, Anastasia; Kufelt, Olga; Schlie-Wolter, Sabrina; Hinze, Ulf; Chichkov, Boris

    2013-10-01

    The two-photon polymerization technique (2PP) uses non-linear absorption of femtosecond laser pulses to selectively polymerize photosensitive materials. 2PP has the ability to fabricate structures with a resolution from tens of micrometers down to hundreds of nanometers. Three-dimensional microstructuring by the 2PP technique provides many interesting possibilities for biomedical applications. This microstructuring technique is suitable with many biocompatible polymeric materials, such as polyethylene glycol, polylactic acid, polycaprolactone, gelatin, zirconium-based hybrids, and others. The process of fabrication does not require clean room conditions and does not use hazard chemicals or high temperatures. The most beneficial property of 2PP is that it is capable of producing especially complex three-dimensional (3-D) structures, including devices with overhangs, without using any supportive structure. The flexibility in controlling geometries and feature sizes and the possibility to fabricate structures without the addition of new material layers makes this technique particularly appealing for fabrication of 3-D scaffolds for tissue engineering. PMID:23729598

  3. Comparison of some biochemical properties of artichoke polyphenol oxidase entrapped in alginate-carrageenan and alginate gels.

    PubMed

    Yagar, Hulya; Kocaturk, Selin

    2014-08-01

    Polyphenol oxidase (PPO, EC.1.14.18.1) isolated from artichoke (Cynara scolymus) was entrapped within alginate and alginate+ carrageenan beads, and the catecholase and cresolase activities of both entrapped enzymes were determined. Some properties of these immobilized enzymes such as optimum pH and temperature, kinetic parameters (Km and Vmax), thermal, and storage stability were determined and compared to each other. The highest catecholase activity was observed in alginate gel (370 U/g bead) while the highest cresolase activity was in alginate+ carrageenan gel (90 U/g bead). For catecholase and cresolase activities, optimum pHs of alginate and alginate+ carrageenan beads were determined to be 7.0 and 4.0, respectively. Optimum temperatures for catecholase activity were determined to be 40°C for both entrapped enzymes. These values for cresolase activity were 30°C and 20°C, respectively. Immobilized artichoke PPOs greatly preserved their thermal stability which exists anyway. The catalytic efficiency value (Vmax/Km) of the alginate beads is approximately high as two-and-a-half folds of that of alginate+κ-carrageenan beads for cresolase activity. These values were very close for catecholase activity. Immobilized beads saved their both activities after 30 days of storage at 4°C. PMID:23795723

  4. Biotechnologically produced microbial alginate dressings show enhanced gel forming capacity compared to commercial alginate dressings of marine origin.

    PubMed

    Hoefer, Dirk; Schnepf, Julia K; Hammer, Timo R; Fischer, Melissa; Marquardt, Christoph

    2015-04-01

    Marine alginate fibre dressings are well established in wound management. Alginate fibres can absorb plenty of wound exudate due to their gel forming abilities and ion exchange. Alginates from bacteria have never been studied for medical applications so far, although the microbial polymer raises expectations for improved gelling capacity due to its unique O-acetylation. To prove the gelling capacity of bacterial alginate, we extracted the co-polymer from fermentation of the soil bacterium Azotobacter vinelandii ATCC 9046, cultivated on crude glycerol as an alternative carbon source. Bacterial alginate was isolated in high purity and extruded by a wet spinning method. Fibre structure and properties were characterised by infrared spectroscopy, NMR, GPC, scanning electron microscopy and tensile testing. The fibres could be processed into biocompatible needle web dressings, which showed more than twice the gel formation in saline compared to commercial dressings made of marine alginates. Gelled dressings of bacterial alginate formed stable hydrogels of sufficient shape and strength for wound healing applications. This work suggests that the increased gel formation of bacterial alginate from A. vinelandii may be optimal for the preparation of novel wound dressings.

  5. Comparison of some biochemical properties of artichoke polyphenol oxidase entrapped in alginate-carrageenan and alginate gels.

    PubMed

    Yagar, Hulya; Kocaturk, Selin

    2014-08-01

    Polyphenol oxidase (PPO, EC.1.14.18.1) isolated from artichoke (Cynara scolymus) was entrapped within alginate and alginate+ carrageenan beads, and the catecholase and cresolase activities of both entrapped enzymes were determined. Some properties of these immobilized enzymes such as optimum pH and temperature, kinetic parameters (Km and Vmax), thermal, and storage stability were determined and compared to each other. The highest catecholase activity was observed in alginate gel (370 U/g bead) while the highest cresolase activity was in alginate+ carrageenan gel (90 U/g bead). For catecholase and cresolase activities, optimum pHs of alginate and alginate+ carrageenan beads were determined to be 7.0 and 4.0, respectively. Optimum temperatures for catecholase activity were determined to be 40°C for both entrapped enzymes. These values for cresolase activity were 30°C and 20°C, respectively. Immobilized artichoke PPOs greatly preserved their thermal stability which exists anyway. The catalytic efficiency value (Vmax/Km) of the alginate beads is approximately high as two-and-a-half folds of that of alginate+κ-carrageenan beads for cresolase activity. These values were very close for catecholase activity. Immobilized beads saved their both activities after 30 days of storage at 4°C.

  6. Scaffolding Performance in EPSSs: Bridging Theory and Practice.

    ERIC Educational Resources Information Center

    Hannafin, Michael J; McCarthy, James E.; Hannafin, Kathleen M.; Radtke, Paul

    Electronic performance support systems (EPSS) help users accomplish tasks, using computational technologies. Scaffolding is the process through which efforts are supported while engaging a learning or performance task. A number of different types of scaffolds are possible, including conceptual, metacognitive, procedural, and strategic. Each of…

  7. Synergistic Scaffolds as a Means to Support Preservice Teacher Learning

    ERIC Educational Resources Information Center

    Van Zoest, Laura R.; Stockero, Shari L.

    2008-01-01

    This study investigates the role of synergistic scaffolds in supporting preservice teachers' knowledge of self-as-teacher. Data include preservice teacher papers written before and after the introduction of scaffolds, surveys, and interviews. Quantitative and qualitative methods were used to analyze differences in the quality of the papers, the…

  8. 3D Printing of Scaffolds for Tissue Regeneration Applications.

    PubMed

    Do, Anh-Vu; Khorsand, Behnoush; Geary, Sean M; Salem, Aliasger K

    2015-08-26

    The current need for organ and tissue replacement, repair, and regeneration for patients is continually growing such that supply is not meeting demand primarily due to a paucity of donors as well as biocompatibility issues leading to immune rejection of the transplant. In order to overcome these drawbacks, scientists have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired an interest in 3D printing as a mode for generating scaffolds. Utilizing three-dimensional printing (3DP) technologies, ECM-like scaffolds can be produced with a high degree of complexity, where fine details can be included at a micrometer level. In this Review, the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering are discussed. Creating biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation. PMID:26097108

  9. 3D Printing of Scaffolds for Tissue Regeneration Applications.

    PubMed

    Do, Anh-Vu; Khorsand, Behnoush; Geary, Sean M; Salem, Aliasger K

    2015-08-26

    The current need for organ and tissue replacement, repair, and regeneration for patients is continually growing such that supply is not meeting demand primarily due to a paucity of donors as well as biocompatibility issues leading to immune rejection of the transplant. In order to overcome these drawbacks, scientists have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired an interest in 3D printing as a mode for generating scaffolds. Utilizing three-dimensional printing (3DP) technologies, ECM-like scaffolds can be produced with a high degree of complexity, where fine details can be included at a micrometer level. In this Review, the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering are discussed. Creating biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation.

  10. Novel biodegradable porous scaffold applied to skin regeneration.

    PubMed

    Wang, Hui-Min; Chou, Yi-Ting; Wen, Zhi-Hong; Wang, Chau-Zen; Wang, Zhao-Ren; Chen, Chun-Hong; Ho, Mei-Ling

    2013-01-01

    Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.5±8.4 µm measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments.

  11. A budget impact analysis comparing a Hydrofiber® ; dressing to an alginate dressing in managing exuding venous leg ulcers in France.

    PubMed

    Yan, Songkai; Colin, Xavier; Coudray-Omnès, Carole; Guido-Morin, Pascale; Kommala, Dheerendra R

    2014-06-01

    An Excel model was developed to compare total costs (including primary and secondary dressings only) of Hydrofiber(®) ; dressing (2010 branded price) versus an alginate dressing (generic or branded price) in managing exuding venous leg ulcers considering mean wear time and mean duration of exudate management phase, from the French Social Security perspective over 5 years (2011-2015). Budget impact (based on prevalence of venous leg ulcers in France) was estimated as the difference between scenario 1 (Hydrofiber(®) ; versus alginate dressing usage proportion increasing slightly per year) and Scenario2 (proportion remaining at 2010 levels). Annual costs and net savings per patient for the dressings were calculated in analyses 1 and 2. Analysis 1 (28-day mean exudate management phase for both Hydrofiber(®) ; and alginate dressing groups): total costs 66·82€ Hydrofiber(®) ;, 70·08€ generic alginate, 77·0€ branded alginate; net savings 3·26€ and 10·18€ for Hydrofiber(®) ; versus generic and branded alginate. Analysis 2 (mean exudate management phase of 22·2 versus 28 days for Hydrofiber(®) ; versus alginate): total costs 52·92€, 70·08€ and 77·0€, and net savings 17·10€ and 24·02€, accordingly. Total cost savings (budget impact scenario 1 minus scenario 2): Analysis 1 - 223 107€ and 696 304€ for Hydrofiber(®) ; versus generic and branded alginate dressings, respectively; Analysis 2 - 1 169 845€ and 1 643 042€ accordingly. Sensitivity analyses indicated that results are reliable. This conservative analysis shows that effective exudate management using Hydrofiber(®) ; dressing can produce sizeable cost savings.

  12. Modified bacterial cellulose scaffolds for localized doxorubicin release in human colorectal HT-29 cells.

    PubMed

    Cacicedo, Maximiliano L; León, Ignacio E; Gonzalez, Jimena S; Porto, Luismar M; Alvarez, Vera A; Castro, Guillermo R

    2016-04-01

    Bacterial cellulose (BC) films modified by the in situ method with the addition of alginate (Alg) during the microbial cultivation of Gluconacetobacter hansenii under static conditions increased the loading of doxorubicin by at least three times. Biophysical analysis of BC-Alg films by scanning electron microscopy, thermogravimetry, X-ray diffraction and FTIR showed a highly homogeneous interpenetrated network scaffold without changes in the BC crystalline structure but with an increased amorphous phase. The main molecular interactions determined by FTIR between both biopolymers clearly suggest high compatibility. These results indicate that alginate plays a key role in the biophysical properties of the hybrid BC matrix. BC-Alg scaffold analysis by nitrogen adsorption isotherms revealed by the Brunauer-Emmett-Teller (BET) method an increase in surface area of about 84% and in pore volume of more than 200%. The Barrett-Joyner-Halenda (BJH) model also showed an increase of about 25% in the pore size compared to the BC film. Loading BC-Alg scaffolds with different amounts of doxorubicin decreased the cell viability of HT-29 human colorectal adenocarcinoma cell line compared to the free Dox from around 95-53% after 24h and from 63% to 37% after 48 h. Dox kinetic release from the BC-Alg nanocomposite displayed hyperbolic curves related to the different amounts of drug payload and was stable for at least 14 days. The results of the BC-Alg nanocomposites show a promissory potential for anticancer therapies of solid tumors. PMID:26784658

  13. Modified bacterial cellulose scaffolds for localized doxorubicin release in human colorectal HT-29 cells.

    PubMed

    Cacicedo, Maximiliano L; León, Ignacio E; Gonzalez, Jimena S; Porto, Luismar M; Alvarez, Vera A; Castro, Guillermo R

    2016-04-01

    Bacterial cellulose (BC) films modified by the in situ method with the addition of alginate (Alg) during the microbial cultivation of Gluconacetobacter hansenii under static conditions increased the loading of doxorubicin by at least three times. Biophysical analysis of BC-Alg films by scanning electron microscopy, thermogravimetry, X-ray diffraction and FTIR showed a highly homogeneous interpenetrated network scaffold without changes in the BC crystalline structure but with an increased amorphous phase. The main molecular interactions determined by FTIR between both biopolymers clearly suggest high compatibility. These results indicate that alginate plays a key role in the biophysical properties of the hybrid BC matrix. BC-Alg scaffold analysis by nitrogen adsorption isotherms revealed by the Brunauer-Emmett-Teller (BET) method an increase in surface area of about 84% and in pore volume of more than 200%. The Barrett-Joyner-Halenda (BJH) model also showed an increase of about 25% in the pore size compared to the BC film. Loading BC-Alg scaffolds with different amounts of doxorubicin decreased the cell viability of HT-29 human colorectal adenocarcinoma cell line compared to the free Dox from around 95-53% after 24h and from 63% to 37% after 48 h. Dox kinetic release from the BC-Alg nanocomposite displayed hyperbolic curves related to the different amounts of drug payload and was stable for at least 14 days. The results of the BC-Alg nanocomposites show a promissory potential for anticancer therapies of solid tumors.

  14. [Strategies to choose scaffold materials for tissue engineering].

    PubMed

    Gao, Qingdong; Zhu, Xulong; Xiang, Junxi; Lü, Yi; Li, Jianhui

    2016-02-01

    Current therapies of organ failure or a wide range of tissue defect are often not ideal. Transplantation is the only effective way for long time survival. But it is hard to meet huge patients demands because of donor shortage, immune rejection and other problems. Tissue engineering could be a potential option. Choosing a suitable scaffold material is an essential part of it. According to different sources, tissue engineering scaffold materials could be divided into three types which are natural and its modified materials, artificial and composite ones. The purpose of tissue engineering scaffold is to repair the tissues or organs damage, so could reach the ideal recovery in its function and structure aspect. Therefore, tissue engineering scaffold should even be as close as much to the original tissue or organs in function and structure. We call it "organic scaffold" and this strategy might be the drastic perfect substitute for the tissues or organs in concern. Optimized organization with each kind scaffold materials could make up for biomimetic structure and function of the tissue or organs. Scaffold material surface modification, optimized preparation procedure and cytosine sustained-release microsphere addition should be considered together. This strategy is expected to open new perspectives for tissue engineering. Multidisciplinary approach including material science, molecular biology, and engineering might find the most ideal tissue engineering scaffold. Using the strategy of drawing on each other strength and optimized organization with each kind scaffold material to prepare a multifunctional biomimetic tissue engineering scaffold might be a good method for choosing tissue engineering scaffold materials. Our research group had differentiated bone marrow mesenchymal stem cells into bile canaliculi like cells. We prepared poly(L-lactic acid)/poly(ε-caprolactone) biliary stent. The scaffold's internal played a part in the long-term release of cytokines which

  15. Human flexor tendon tissue engineering: revitalization of biostatic allograft scaffolds.

    PubMed

    Woon, Colin Y L; Farnebo, Simon; Schmitt, Taliah; Kraus, Armin; Megerle, Kai; Pham, Hung; Yan, Xinrui; Gambhir, Sanjiv S; Chang, James

    2012-12-01

    Cadaveric tendon allografts form a readily available and underutilized source of graft material. Because of their material properties, allografts are biomechanically and biologically superior to synthetic scaffolds. However, before clinical use, allografts must undergo decellularization to reduce immunogenicity and oxidation to increase porosity, leaving a nonvital biostatic scaffold. Ex vivo seeding, or revitalization, is thought to hasten graft incorporation and stimulate intrinsic tendon healing, permitting early mobilization and return to function. In this study, we examined physical and biochemical augmentation methods, including scaffold surface scoring (physical) and rehydration of lyophilized scaffolds in serum (biochemical). Scaffolds were divided into four groups: (1) scored scaffolds, (2) lyophilized scaffolds rehydrated in fetal calf serum (FCS), (3) scaffolds both scored and rehydrated in FCS, and (4) control scaffolds. Scaffolds were reseeded with adipose-derived stem cells (ADSCs). Reseeding efficacy was quantified by a live cell and total cell assays and qualified histologically with hematoxylin and eosin, live/dead and SYTO green nucleic acid stains, TUNEL apoptosis stains, procollagen stains, and transmission electron microscopy. Scaffold-seeded cell viability at up to 2 weeks in vitro and up to 4 weeks in vivo was demonstrated with bioluminescent imaging of scaffolds seeded with luciferase-positive ADSCs. The effect of seeding on scaffold biomechanical properties was demonstrated with evaluation of ultimate tensile stress (UTS) and an elastic modulus (EM). We found that scaffold surface scoring led to an increase in live and total cell attachment and penetration (MTS assay, p<0.001 and DNA assay, p=0.003, respectively). Histology confirmed greater total cell number in both construct core and surface in scored compared with unscored constructs. Cells reseeded on scored constructs displayed reduced apoptosis, persistent procollagen production, and

  16. [Strategies to choose scaffold materials for tissue engineering].

    PubMed

    Gao, Qingdong; Zhu, Xulong; Xiang, Junxi; Lü, Yi; Li, Jianhui

    2016-02-01

    Current therapies of organ failure or a wide range of tissue defect are often not ideal. Transplantation is the only effective way for long time survival. But it is hard to meet huge patients demands because of donor shortage, immune rejection and other problems. Tissue engineering could be a potential option. Choosing a suitable scaffold material is an essential part of it. According to different sources, tissue engineering scaffold materials could be divided into three types which are natural and its modified materials, artificial and composite ones. The purpose of tissue engineering scaffold is to repair the tissues or organs damage, so could reach the ideal recovery in its function and structure aspect. Therefore, tissue engineering scaffold should even be as close as much to the original tissue or organs in function and structure. We call it "organic scaffold" and this strategy might be the drastic perfect substitute for the tissues or organs in concern. Optimized organization with each kind scaffold materials could make up for biomimetic structure and function of the tissue or organs. Scaffold material surface modification, optimized preparation procedure and cytosine sustained-release microsphere addition should be considered together. This strategy is expected to open new perspectives for tissue engineering. Multidisciplinary approach including material science, molecular biology, and engineering might find the most ideal tissue engineering scaffold. Using the strategy of drawing on each other strength and optimized organization with each kind scaffold material to prepare a multifunctional biomimetic tissue engineering scaffold might be a good method for choosing tissue engineering scaffold materials. Our research group had differentiated bone marrow mesenchymal stem cells into bile canaliculi like cells. We prepared poly(L-lactic acid)/poly(ε-caprolactone) biliary stent. The scaffold's internal played a part in the long-term release of cytokines which

  17. Cryopreservation effects on recombinant myoblasts encapsulated in adhesive alginate hydrogels.

    PubMed

    Ahmad, Hajira F; Sambanis, Athanassios

    2013-06-01

    Cell encapsulation in hydrogels is widely used in tissue engineering applications, including encapsulation of islets or other insulin-secreting cells in pancreatic substitutes. Use of adhesive, biofunctionalized hydrogels is receiving increasing attention as cell-matrix interactions in three-dimensional (3-D) environments can be important for various cell processes. With pancreatic substitutes, studies have indicated benefits of 3-D adhesion on the viability and/or function of insulin-secreting cells. As long-term storage of microencapsulated cells is critical for their clinical translation, cryopreservation of cells in hydrogels is being actively investigated. Previous studies have examined the cryopreservation response of cells encapsulated in non-adhesive hydrogels using conventional freezing and/or vitrification (ice-free cryopreservation); however, none have systematically compared the two cryopreservation methods with cells encapsulated within an adhesive 3-D environment. The latter would be significant, as evidence suggests adhesion influences the cellular response to cryopreservation. Thus, the objective of this study was to determine the response to conventional freezing and vitrification of insulin-secreting cells encapsulated in an adhesive biomimetic hydrogel. Recombinant insulin-secreting C2C12 myoblasts were encapsulated in oxidized RGD-alginate and cultured for 1 or 4days post-encapsulation, cryopreserved, and assessed up to 3days post-warming for metabolic activity and insulin secretion, and 1day post-warming for cell morphology. Besides certain transient differences in the vitrified group relative to the fresh control, both conventional freezing and vitrification maintained the metabolism, secretory activity, and morphology of the recombinant C2C12 cells. Thus, due to a simpler procedure and slightly superior results, conventional freezing is recommended over vitrification for the cryopreservation of C2C12 cells encapsulated in oxidized, RGD

  18. A Transient Cell-Shielding Method for Viable MSC Delivery within Hydrophobic Scaffolds Polymerized In Situ

    PubMed Central

    Guo, Ruijing; Ward, Catherine L.; Davidson, Jeffrey M.; Duvall, Craig L.; Wenke, Joseph C.

    2015-01-01

    Cell-based therapies have emerged as promising approaches for regenerative medicine. Hydrophobic poly(ester urethane)s offer the advantages of robust mechanical properties, cell attachment without the use of peptides, and controlled degradation by oxidative and hydrolytic mechanisms. However, the application of injectable hydrophobic polymers to cell delivery is limited by the challenges of protecting cells from reaction products and creating a macroporous architecture post-cure. We designed injectable carriers for cell delivery derived from reactive, hydrophobic polyisocyanate and polyester triol precursors. To overcome cell death caused by reaction products from in situ polymerization, we encapsulated bone marrow-derived stem cells (BMSCs) in fast-degrading, oxidized alginate beads prior to mixing with the hydrophobic precursors. Cells survived the polymerization at >70% viability, and rapid dissolution of oxidized alginate beads after the scaffold cured created interconnected macropores that facilitated cellular adhesion to the scaffold in vitro. Applying this injectable system to deliver BMSCs to rat excisional skin wounds showed that the scaffolds supported survival of transplanted cells and infiltration of host cells, which improved new tissue formation compared to both implanted, pre-formed scaffolds seeded with cells and acellular controls. Our design is the first to enable injectable delivery of settable, hydrophobic scaffolds where cell encapsulation provides a mechanism for both temporary cytoprotection during polymerization and rapid formation of macropores post-polymerization. This simple approach provides potential advantages for cell delivery relative to hydrogel technologies, which have weaker mechanical properties and require incorporation of peptides to achieve cell adhesion and degradability. PMID:25907036

  19. Carbon nanotubes as vaccine scaffolds

    PubMed Central

    Scheinberg, David A.; McDevitt, Michael R.; Dao, Tao; Mulvey, Justin J.; Feinberg, Evan; Alidori, Simone

    2013-01-01

    Carbon nanotubes display characteristics that are potentially useful in their development as scaffolds for vaccine compositions. These features include stability in vivo, lack of intrinsic immunogenicity, low toxicity, and the ability to be appended with multiple copies of antigens. In addition, the particulate nature of carbon nanotubes and their unusual properties of rapid entry into antigen-presenting cells, such as dendritic cells, make them especially useful as carriers of antigens. Early attempts demonstrating carbon nanotube-based vaccines can be used in both infectious disease settings and cancer are promising. PMID:23899863

  20. Biomimetic Scaffolds for Osteogenesis

    PubMed Central

    Yuan, Nance; Rezzadeh, Kameron S.; Lee, Justine C.

    2015-01-01

    Skeletal regenerative medicine emerged as a field of investigation to address large osseous deficiencies secondary to congenital, traumatic, and post-oncologic conditions. Although autologous bone grafts have been the gold standard for reconstruction of skeletal defects, donor site morbidity remains a significant limitation. To address these limitations, contemporary bone tissue engineering research aims to target delivery of osteogenic cells and growth factors in a defined three dimensional space using scaffolding material. Using bone as a template, biomimetic strategies in scaffold engineering unite organic and inorganic components in an optimal configuration to both support osteoinduction as well as osteoconduction. This article reviews the various structural and functional considerations behind the development of effective biomimetic scaffolds for osteogenesis and highlights strategies for enhancing osteogenesis. PMID:26413557

  1. Evaluation of sodium alginate as drug release modifier in matrix tablets.

    PubMed

    Liew, Celine Valeria; Chan, Lai Wah; Ching, Ai Ling; Heng, Paul Wan Sia

    2006-02-17

    Alginates are useful natural polymers suitable for use in the design of pharmaceutical dosage forms. However, the effects of particle size, viscosity and chemical composition of alginates on drug release from alginate matrix tablets are not clearly understood. Hence, 17 grades of sodium alginate with different particle size distributions, viscosities and chemical compositions were used to prepare matrix tablets at various concentrations to screen the factors influencing drug release from such matrices. Particle size was found to have an influence on drug release from these matrices. Sodium alginate was subsequently classified into several size fractions and also cryogenically milled to produce smaller particle size samples. Cryogenic milling could be successfully applied to pulverize coarse alginate particles without changing the quality through degradation or segregation. This study showed the significance of each alginate property in modulating drug release: particle size is important in initial alginic acid gel barrier formation as it affected the extent of burst release; higher alginate viscosity slowed down drug release rate in the buffer phase but enhanced release rate in the acid phase; high M-alginate might be more advantageous than high-G-alginate in sustaining drug release; and, the effect of increasing alginate concentration was greater with larger alginate particles. This can serve as a framework for formulators working with alginates. Furthermore, the results showed that sodium alginate matrices can sustain drug release for at least 8 h, even for a highly water-soluble drug in the presence of a water-soluble excipient. PMID:16364576

  2. Magnetically actuated tissue engineered scaffold: insights into mechanism of physical stimulation

    NASA Astrophysics Data System (ADS)

    Sapir-Lekhovitser, Yulia; Rotenberg, Menahem Y.; Jopp, Juergen; Friedman, Gary; Polyak, Boris; Cohen, Smadar

    2016-02-01

    Providing the right stimulatory conditions resulting in efficient tissue promoting microenvironment in vitro and in vivo is one of the ultimate goals in tissue development for regenerative medicine. It has been shown that in addition to molecular signals (e.g. growth factors) physical cues are also required for generation of functional cell constructs. These cues are particularly relevant to engineering of biological tissues, within which mechanical stress activates mechano-sensitive receptors, initiating biochemical pathways which lead to the production of functionally mature tissue. Uniform magnetic fields coupled with magnetizable nanoparticles embedded within three dimensional (3D) scaffold structures remotely create transient physical forces that can be transferrable to cells present in close proximity to the nanoparticles. This study investigated the hypothesis that magnetically responsive alginate scaffold can undergo reversible shape deformation due to alignment of scaffold's walls in a uniform magnetic field. Using custom made Helmholtz coil setup adapted to an Atomic Force Microscope we monitored changes in matrix dimensions in situ as a function of applied magnetic field, concentration of magnetic particles within the scaffold wall structure and rigidity of the matrix. Our results show that magnetically responsive scaffolds exposed to an externally applied time-varying uniform magnetic field undergo a reversible shape deformation. This indicates on possibility of generating bending/stretching forces that may exert a mechanical effect on cells due to alternating pattern of scaffold wall alignment and relaxation. We suggest that the matrix structure deformation is produced by immobilized magnetic nanoparticles within the matrix walls resulting in a collective alignment of scaffold walls upon magnetization. The estimated mechanical force that can be imparted on cells grown on the scaffold wall at experimental conditions is in the order of 1 pN, which

  3. Magnetically actuated tissue engineered scaffold: insights into mechanism of physical stimulation.

    PubMed

    Sapir-Lekhovitser, Yulia; Rotenberg, Menahem Y; Jopp, Juergen; Friedman, Gary; Polyak, Boris; Cohen, Smadar

    2016-02-14

    Providing the right stimulatory conditions resulting in efficient tissue promoting microenvironment in vitro and in vivo is one of the ultimate goals in tissue development for regenerative medicine. It has been shown that in addition to molecular signals (e.g. growth factors) physical cues are also required for generation of functional cell constructs. These cues are particularly relevant to engineering of biological tissues, within which mechanical stress activates mechano-sensitive receptors, initiating biochemical pathways which lead to the production of functionally mature tissue. Uniform magnetic fields coupled with magnetizable nanoparticles embedded within three dimensional (3D) scaffold structures remotely create transient physical forces that can be transferrable to cells present in close proximity to the nanoparticles. This study investigated the hypothesis that magnetically responsive alginate scaffold can undergo reversible shape deformation due to alignment of scaffold's walls in a uniform magnetic field. Using custom made Helmholtz coil setup adapted to an Atomic Force Microscope we monitored changes in matrix dimensions in situ as a function of applied magnetic field, concentration of magnetic particles within the scaffold wall structure and rigidity of the matrix. Our results show that magnetically responsive scaffolds exposed to an externally applied time-varying uniform magnetic field undergo a reversible shape deformation. This indicates on possibility of generating bending/stretching forces that may exert a mechanical effect on cells due to alternating pattern of scaffold wall alignment and relaxation. We suggest that the matrix structure deformation is produced by immobilized magnetic nanoparticles within the matrix walls resulting in a collective alignment of scaffold walls upon magnetization. The estimated mechanical force that can be imparted on cells grown on the scaffold wall at experimental conditions is in the order of 1 pN, which

  4. Chitosan-alginate membranes accelerate wound healing.

    PubMed

    Caetano, Guilherme Ferreira; Frade, Marco Andrey Cipriani; Andrade, Thiago Antônio Moretti; Leite, Marcel Nani; Bueno, Cecilia Zorzi; Moraes, Ângela Maria; Ribeiro-Paes, João Tadeu

    2015-07-01

    The purpose of this study was to evaluate the efficacy of chitosan-alginate membrane to accelerate wound healing in experimental cutaneous wounds. Two wounds were performed in Wistar rats by punching (1.5 cm diameter), treated with membranes moistened with saline solution (CAM group) or with saline only (SL group). After 2, 7, 14, and 21 days of surgery, five rats of each group were euthanized and reepithelialization was evaluated. The wounds/scars were harvested for histological, flow cytometry, neutrophil infiltrate, and hydroxyproline analysis. CAM group presented higher inflammatory cells recruitment as compared to SL group on 2(nd) day. On the 7(th) day, CAM group showed higher CD11b(+) level and lower of neutrophils than SL group. The CAM group presented higher CD4(+) cells influx than SL group on 2(nd) day, but it decreased during the follow up and became lower on 14(th) and 21(st) days. Higher fibroplasia was noticed on days 7 and 14 as well as higher collagenesis on 21(st) in the CAM group in comparison to SL group. CAM group showed faster reepithelialization on 7(th) day than SL group, although similar in other days. In conclusion, chitosan-alginate membrane modulated the inflammatory phase, stimulated fibroplasia and collagenesis, accelerating wound healing process in rats.

  5. Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

    PubMed

    Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

    2016-10-01

    The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (<50μm) were investigated in this work as carriers for mucosal administration of drugs. Low methoxyl pectin and κ-carrageenan were co-gelled with alginate and further dried with supercritical CO2 (sc-CO2). Spherical mesoporous aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications.

  6. Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

    PubMed

    Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

    2016-10-01

    The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (<50μm) were investigated in this work as carriers for mucosal administration of drugs. Low methoxyl pectin and κ-carrageenan were co-gelled with alginate and further dried with supercritical CO2 (sc-CO2). Spherical mesoporous aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications. PMID:27393563

  7. An anomalous behavior of trypsin immobilized in alginate network.

    PubMed

    Ganachaud, Chrystelle; Bernin, Diana; Isaksson, Dan; Holmberg, Krister

    2013-05-01

    Alginate is a biopolymer used in drug formulations and for surgical purposes. In the presence of divalent cations, it forms solid gels, and such gels are of interest for immobilization of cells and enzymes. In this work, we entrapped trypsin in an alginate gel together with a known substrate, N α-benzoyl-L-arginine-4-nitroanilide hydrochloride (L-BAPNA), and in the presence or absence of D-BAPNA, which is known to be a competitive inhibitor. Interactions between alginate and the substrate as well as the enzyme were characterized with transmission electron microscopy, rheology, and nuclear magnetic resonance spectroscopy. The biocatalysis was monitored by spectrophotometry at temperatures ranging from 10 to 42 °C. It was found that at 37 and 42 °C a strong acceleration of the reaction was obtained, whereas at 10 °C and at room temperature, the presence of D-BAPNA leads to a retardation of the reaction rate. The same effect was found when the reaction was performed in a non-cross-linked alginate solution. In alginate-free buffer solution, as well as in a solution of carboxymethylcellulose, a biopolymer that resembles alginate, the normal behavior was obtained; however, with D-BAPNA acting as an inhibitor at all temperatures. A more detailed investigation of the reaction kinetics showed that at higher temperature and in the presence of alginate, the curve of initial reaction rate versus L-BAPNA concentration had a sigmoidal shape, indicating an allosteric behavior. We believe that the anomalous behavior of trypsin in the presence of alginate is due to conformational changes caused by interactions between the positively charged trypsin and the strongly negatively charged alginate.

  8. Cell Infiltration and Growth in a Low Density, Uncompressed Three-Dimensional Electrospun Nanofibrous Scaffold

    PubMed Central

    Blakeney, Bryan A.; Tambralli, Ajay; Anderson, Joel M.; Andukuri, Adinarayana; Lim, Dong-Jin; Dean, Derrick R.; Jun, Ho-Wook

    2010-01-01

    A limiting factor of traditional electrospinning is that the electrospun scaffolds consist entirely of tightly packed nanofiber layers that only provide a superficial porous structure due to the sheet-like assembly process. This unavoidable characteristic hinders cell infiltration and growth throughout the nanofibrous scaffolds. Numerous strategies have been tried to overcome this challenge, including the incorporation of nanoparticles, using larger microfibers, or removing embedded salt or water-soluble fibers to increase porosity. However, these methods still produce sheet-like nanofibrous scaffolds, failing to create a porous three-dimensional scaffold with good structural integrity. Thus, we have developed a three-dimensional cotton ball-like electrospun scaffold that consists of an accumulation of nanofibers in a low density and uncompressed manner. Instead of a traditional flat-plate collector, a grounded spherical dish and an array of needle-like probes were used to create a Focused, Low density, Uncompressed nanoFiber (FLUF) mesh scaffold. Scanning electron microscopy showed that the cotton ball-like scaffold consisted of electrospun nanofibers with a similar diameter but larger pores and less dense structure compared to the traditional electrospun scaffolds. In addition, laser confocal microscopy demonstrated an open porosity and loosely packed structure throughout the depth of the cotton ball-like scaffold, contrasting the superficially porous and tightly packed structure of the traditional electrospun scaffold. Cells seeded on the cotton ball-like scaffold infiltrated into the scaffold after 7 days of growth, compared to no penetrating growth for the traditional electrospun scaffold. Quantitative analysis showed approximately a 40% higher growth rate for cells on the cotton ball-like scaffold over a 7 day period, possibly due to the increased space for in-growth within the three-dimensional scaffolds. Overall, this method assembles a nanofibrous scaffold

  9. Chemical modification of alginic acid by ultrasonic irradiation

    NASA Astrophysics Data System (ADS)

    Murdzheva, Dilyana; Denev, Panteley

    2016-03-01

    Abstract: Chemical modification of alginic acid has been done by ultrasonic irradiation to obtain its methylated, ethylated and isopropylated derivatives. The influence of ultrasonic frequency and power on esterification process of alginic acid has been investigated. Alginate derivatives have been characterized by degree of esterification (DE) and IR-FT spectroscopy. It has been found that 45 kHz ultrasonic frequency accelerated modification process as reduced the reaction time from 16 hours to 2 hours. The obtained results showed that ultrasound irradiation increased the reaction efficiency in methanol and depended on the ratio of the M/G.

  10. L_RNA_scaffolder: scaffolding genomes with transcripts

    PubMed Central

    2013-01-01

    Background Generation of large mate-pair libraries is necessary for de novo genome assembly but the procedure is complex and time-consuming. Furthermore, in some complex genomes, it is hard to increase the N50 length even with large mate-pair libraries, which leads to low transcript coverage. Thus, it is necessary to develop other simple scaffolding approaches, to at least solve the elongation of transcribed fragments. Results We describe L_RNA_scaffolder, a novel genome scaffolding method that uses long transcriptome reads to order, orient and combine genomic fragments into larger sequences. To demonstrate the accuracy of the method, the zebrafish genome was scaffolded. With expanded human transcriptome data, the N50 of human genome was doubled and L_RNA_scaffolder out-performed most scaffolding results by existing scaffolders which employ mate-pair libraries. In these two examples, the transcript coverage was almost complete, especially for long transcripts. We applied L_RNA_scaffolder to the highly polymorphic pearl oyster draft genome and the gene model length significantly increased. Conclusions The simplicity and high-throughput of RNA-seq data makes this approach suitable for genome scaffolding. L_RNA_scaffolder is available at http://www.fishbrowser.org/software/L_RNA_scaffolder. PMID:24010822

  11. Electrospun Silk Biomaterial Scaffolds for Regenerative Medicine

    PubMed Central

    Zhang, Xiaohui; Reagan, Michaela R; Kaplan, David L.

    2009-01-01

    Electrospinning is a versatile technique that enables the development of nanofiber-based biomaterial scaffolds. Scaffolds can be generated that are useful for tissue engineering and regenerative medicine since they mimic the nanoscale properties of certain fibrous components of the native extracellular matrix in tissues. Silk is a natural protein with excellent biocompatibility, remarkable mechanical properties as well as tailorable degradability. Integrating these protein polymer advantages with electrospinning results in scaffolds with combined biochemical, topographical and mechanical cues with versatility for a range of biomaterial, cell and tissue studies and applications. This review covers research related to electrospinning of silk, including process parameters, post treatment of the spun fibers, functionalization of nanofibers, and the potential applications for these material systems in regenerative medicine. Research challenges and future trends are also discussed. PMID:19643154

  12. Immune Response to Biologic Scaffold Materials

    PubMed Central

    Badylak, Stephen F.; Gilbert, Thomas W.

    2008-01-01

    Biologic scaffold materials composed of mammalian extracellular matrix are commonly used in regenerative medicine and in surgical procedures for the reconstruction of numerous tissue and organs. These biologic materials are typically allogeneic or xenogeneic in origin and are derived from tissues such as small intestine, urinary bladder, dermis, and pericardium. The innate and acquired host immune response to these biologic materials and the effect of the immune response upon downstream remodeling events has been largely unexplored. Variables that affect the host response include manufacturing processes, the rate of scaffold degradation, and the presence of cross species antigens. This manuscript provides an overview of studies that have evaluated the immune response to biologic scaffold materials and variables that affect this response. PMID:18083531

  13. Silk Fibroin Scaffolds for Urologic Tissue Engineering.

    PubMed

    Sack, Bryan S; Mauney, Joshua R; Estrada, Carlos R

    2016-02-01

    Urologic tissue engineering efforts have been largely focused on bladder and urethral defect repair. The current surgical gold standard for treatment of poorly compliant pathological bladders and severe urethral stricture disease is enterocystoplasty and onlay urethroplasty with autologous tissue, respectively. The complications associated with autologous tissue use and harvesting have led to efforts to develop tissue-engineered alternatives. Natural and synthetic materials have been used with varying degrees of success, but none has proved consistently reliable for urologic tissue defect repair in humans. Silk fibroin (SF) scaffolds have been tested in bladder and urethral repair because of their favorable biomechanical properties including structural strength, elasticity, biodegradability, and biocompatibility. SF scaffolds have been used in multiple animal models and have demonstrated robust regeneration of smooth muscle and urothelium. The pre-clinical data involving SF scaffolds in urologic defect repair are encouraging and suggest that they hold potential for future clinical use.

  14. Producing ORMOSIL scaffolds by femtosecond laser polymerization

    NASA Astrophysics Data System (ADS)

    Matei, A.; Zamfirescu, M.; Radu, C.; Buruiana, E. C.; Buruiana, T.; Mustaciosu, C.; Petcu, I.; Radu, M.; Dinescu, M.

    2012-07-01

    Structures with different geometries and sizes were built via direct femtosecond laser writing, starting from new organic/inorganic hybrid monomers based on hybrid methacrylate containing triethoxysilane, in addition to urethane and urea groups. Multifunctional oligomer of urethane dimethacrylate type was chosen as comonomer in polymerization experiments because dimethacrylates give rise to the formation of a polymer network, having a number of favorable properties including biocompatibility and surface nanostructuring. Free standing polymeric structures were designed and created in order to be tested in fibroblast cells culture. Investigations of the cellular adhesion, proliferation, and viability of L929 mouse fibroblasts on free-standing laser processed scaffolds were performed for different scaffold designs.

  15. An Investigation of Software Scaffolds Supporting Modeling Practices

    NASA Astrophysics Data System (ADS)

    Fretz, Eric B.; Wu, Hsin-Kai; Zhang, Baohui; Davis, Elizabeth A.; Krajcik, Joseph S.; Soloway, Elliot

    2002-08-01

    Modeling of complex systems and phenomena is of value in science learning and is increasingly emphasised as an important component of science teaching and learning. Modeling engages learners in desired pedagogical activities. These activities include practices such as planning, building, testing, analysing, and critiquing. Designing realistic models is a difficult task. Computer environments allow the creation of dynamic and even more complex models. One way of bringing the design of models within reach is through the use of scaffolds. Scaffolds are intentional assistance provided to learners from a variety of sources, allowing them to complete tasks that would otherwise be out of reach. Currently, our understanding of how scaffolds in software tools assist learners is incomplete. In this paper the scaffolds designed into a dynamic modeling software tool called Model-It are assessed in terms of their ability to support learners' use of modeling practices. Four pairs of middle school students were video-taped as they used the modeling software for three hours, spread over a two week time frame. Detailed analysis of coded videotape transcripts provided evidence of the importance of scaffolds in supporting the use of modeling practices. Learners used a variety of modeling practices, the majority of which occurred in conjunction with scaffolds. The use of three tool scaffolds was assessed as directly as possible, and these scaffolds were seen to support a variety of modeling practices. An argument is made for the continued empirical validation of types and instances of tool scaffolds, and further investigation of the important role of teacher and peer scaffolding in the use of scaffolded tools.

  16. Encapsulation of liquid smoke flavoring in ca-alginate and ca-alginate-chitosan beads.

    PubMed

    Petzold, Guillermo; Gianelli, María Pia; Bugueño, Graciela; Celan, Raymond; Pavez, Constanza; Orellana, Patricio

    2014-01-01

    Encapsulation is a technique used in foods that may protect some compounds with sensory impact, in particular flavoring as liquid smoke. We used the dripping method, obtaining two different layers for encapsulation of liquid smoke: calcium alginate and calcium alginate-chitosan. The results show that the load capacity of liquid smoke encapsulation reached values above 96 %. The beads exhibit syneresis at room temperature, but in opposite side, refrigeration temperature stabilizes the hydrogel of beads, allowing the samples loss weight less than 3 % after 72 h. Heated capsules with liquid smoke released several volatile compounds in the headspace and may identify 66 compounds. Among these volatile compounds, phenols derivatives can be considered sensory descriptors to contribute to the specific flavor of smoke. We conclude that the dripping method is highly efficient to encapsulate liquid smoke and released several volatile compounds, although it is necessary to minimize syneresis at room temperature.

  17. Autologous fibrin scaffolds cultured dermal fibroblasts and enriched with encapsulated bFGF for tissue engineering.

    PubMed

    de la Puente, Pilar; Ludeña, Dolores; Fernández, Ana; Aranda, Jose L; Varela, Gonzalo; Iglesias, Javier

    2011-12-15

    Autologous fibrin scaffolds (AFSs) enriched with cells and specific growth factors represent a promising biocompatible scaffold for tissue engineering. Here, we analyzed the in vitro behavior of dermal fibroblasts (DFs) (cellular attachment, distribution, viability and proliferation, histological and immunohistochemical changes), comparing AFS with and without alginate microcapsules loaded with basic fibroblast growth factor (bFGF), to validate our scaffold in a future animal model in vivo. In all cases, DFs showed good adhesion and normal distribution, while in scaffolds with bFGF at 14 days, the cell counts detected in proliferation and viability assays were greatly improved, as was the proliferative state, and there was a decrease in muscle specific actin expression and collagen synthesis in comparison with the scaffolds without bFGF. In addition, the use of plasma without fibrinogen concentration methods, together with the maximum controlled release of bFGF at 14 days, favored cell proliferation. To conclude, we have been able to create an AFS enriched with fully functional DFs and release-controlled bFGF that could be used in multiple applications for tissue engineering.

  18. Genetics of Bacterial Alginate: Alginate Genes Distribution, Organization and Biosynthesis in Bacteria

    PubMed Central

    Muhammadi; Ahmed, Nuzhat

    2007-01-01

    Bacterial alginate genes are chromosomal and fairly widespread among rRNA homology group I Pseudomonads and Azotobacter. In both genera, the genetic pathway of alginate biosynthesis is mostly similar and the identified genes are identically organized into biosynthetic, regulatory and genetic switching clusters. In spite of these similarities,still there are transcriptional and functional variations between P. aeruginosa and A. vinelandii. In P. aeruginosa all biosynthetic genes except algC transcribe in polycistronic manner under the control of algD promoter while in A. vinelandii, these are organized into many transcriptional units. Of these, algA and algC are transcribed each from two different and algD from three different promoters. Unlike P. aeruginosa, the promoters of these transcriptional units except one of algC and algD are algT-independent. Both bacterial species carry homologous algG gene for Ca2+-independent epimerization. But besides algG, A. vinelandii also has algE1-7 genes which encode C-5-epimerases involved in the complex steps of Ca2+-dependent epimerization. A hierarchy of alginate genes expression under σ22(algT) control exists in P. aeruginosa where algT is required for transcription of the response regulators algB and algR, which in turn are necessary for expression of algD and its downstream biosynthetic genes. Although algTmucABCD genes cluster play similar regulatory roles in both P. aeruginosa and A. vinelandii but unlike, transcription of A. vinelandii, algR is independent of σ22. These differences could be due to the fact that in A. vinelandii alginate plays a role as an integrated part in desiccation-resistant cyst which is not found in P. aeruginosa. PMID:18645604

  19. Mathematical Abstraction through Scaffolding

    ERIC Educational Resources Information Center

    Ozmantar, Mehmet Fatih; Roper, Tom

    2004-01-01

    This paper examines the role of scaffolding in the process of abstraction. An activity-theoretic approach to abstraction in context is taken. This examination is carried out with reference to verbal protocols of two 17 year-old students working together on a task connected to sketching the graph of |f|x|)|. Examination of the data suggests that…

  20. Engineered yeast whole-cell biocatalyst for direct degradation of alginate from macroalgae and production of non-commercialized useful monosaccharide from alginate.

    PubMed

    Takagi, Toshiyuki; Yokoi, Takahiro; Shibata, Toshiyuki; Morisaka, Hironobu; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2016-02-01

    Alginate is a major component of brown macroalgae. In macroalgae, an endolytic alginate lyase first degrades alginate into oligosaccharides. These oligosaccharides are further broken down into monosaccharides by an exolytic alginate lyase. In this study, genes encoding various alginate lyases derived from alginate-assimilating marine bacterium Saccharophagus degradans were isolated, and their enzymes were displayed using the yeast cell surface display system. Alg7A-, Alg7D-, and Alg18J-displaying yeasts showed endolytic alginate lyase activity. On the other hand, Alg7K-displaying yeast showed exolytic alginate lyase activity. Alg7A, Alg7D, Alg7K, and Alg18J, when displayed on yeast cell surface, demonstrated both polyguluronate lyase and polymannuronate lyase activities. Additionally, polyguluronic acid could be much easily degraded by Alg7A, Alg7K, and Alg7D than polymannuronic acid. In contrast, polymannuronic acid could be much easily degraded by Alg18J than polyguluronic acid. We further constructed yeasts co-displaying endolytic and exolytic alginate lyases. Degradation efficiency by the co-displaying yeasts were significantly higher than single alginate lyase-displaying yeasts. Alg7A/Alg7K co-displaying yeast had maximum alginate degrading activity, with production of 1.98 g/L of reducing sugars in a 60-min reaction. This system developed, along with our findings, will contribute to the efficient utilization and production of useful and non-commercialized monosaccharides from alginate by Saccharomyces cerevisiae. PMID:26490549

  1. Fabrication of cross-linked alginate beads using electrospraying for adenovirus delivery.

    PubMed

    Park, Hongkwan; Kim, Pyung-Hwan; Hwang, Taewon; Kwon, Oh-Joon; Park, Tae-Joon; Choi, Sung-Wook; Yun, Chae-Ok; Kim, Jung Hyun

    2012-05-10

    Cross-linked alginate beads containing adenovirus (Ad) were successfully fabricated using an electrospraying method to achieve the protection and release of Ad in a controlled manner. An aqueous alginate solution containing Ad was electrosprayed into an aqueous phase containing a cross-linking agent (calcium chloride) at different process variables (voltages, alginate concentrations, and flow rates). Alginate beads containing Ad were used for transduction of U343 glioma cells and the transduction efficiency of the alginate beads was measured by quantification of gene expression using a fluorescence-activated cell sorter at different time points. In vitro results of gene expression revealed that the Ad encapsulated in the alginate beads with 0.5 wt% of alginate concentration exhibited a high activity for a long period (over 7 days) and was released in a sustained manner from the alginate beads. The Ad-encapsulating alginate beads could be promising materials for local delivery of Ad at a high concentration into target sites.

  2. Preparation of novel silica-coated alginate gel beads for efficient encapsulation of yeast alcohol dehydrogenase.

    PubMed

    Xu, Song-Wei; Lu, Yang; Li, Jian; Zhang, Yu-Fei; Jiang, Zhong-Yi

    2007-01-01

    Biomimetic formation has undoubtedly inspired the preparation of novel organic-inorganic hybrid composites. In this study, silica-coated alginate gel beads were prepared by coating the surface of alginate gel beads with silica film derived from tetramethoxysilane (TMOS). The composition and structure of the silica film were characterized by FT-IR and SEM equipped with EDX. The swelling behavior of silica-coated alginate gel beads was studied to be more stable against swelling than that of alginate gel beads. The results showed that silica-coated alginate gel beads exhibited appropriate diffusion property. The effective diffusion coefficient (D(e)) of NADH in silica-coated alginate beads was 1.76 x 10(-10) m2/s, while the effective diffusion coefficient in alginate beads was 1.84 x 10(-10) m2/s. The model enzyme yeast alcohol dehydrogenase (YADH) was encapsulated in silica-coated alginate and pure alginate beads, respectively. Enzyme leakage of YADH in alginate gel beads was determined to be 32%, while the enzyme leakage in silica-coated alginate gel beads was as low as 11%. Furthermore, the relative activity of YADH in alginate gel beads decreased almost to zero after 10 recycles, while the relative activity of YADH in silica-coated alginate gel beads was 81.3%. The recycling stability of YADH in silica-coated alginate gel beads was found to be increased significantly mainly due to the effective inhibition of enzyme leakage by compact silica film.

  3. Design Strategies of Biodegradable Scaffolds for Tissue Regeneration

    PubMed Central

    Bitar, Khalil N; Zakhem, Elie

    2014-01-01

    There are numerous available biodegradable materials that can be used as scaffolds in regenerative medicine. Currently, there is a huge emphasis on the designing phase of the scaffolds. Materials can be designed to have different properties in order to match the specific application. Modifying scaffolds enhances their bioactivity and improves the regeneration capacity. Modifications of the scaffolds can be later characterized using several tissue engineering tools. In addition to the material, cell source is an important component of the regeneration process. Modified materials must be able to support survival and growth of different cell types. Together, cells and modified biomaterials contribute to the remodeling of the engineered tissue, which affects its performance. This review focuses on the recent advancements in the designs of the scaffolds including the physical and chemical modifications. The last part of this review also discusses designing processes that involve viability of cells. PMID:25288907

  4. The angiogenesis in decellularized scaffold-mediated the renal regeneration

    PubMed Central

    Li, Miaozhong; Xi, Shanshan; Zhang, Sixiao; Liu, Xiaolin; Jiang, Junqun; Wang, Zhibin; Zhang, Jianse; Ding, Yuqiang; Lou, Xinfa; Tang, Maolin

    2016-01-01

    There are increasing numbers of patients underwent partial nephrectomy, and recovery of disturbed renal function is imperative post partial nephrectomy. We previously have demonstrated the decellularized (DC) scaffolds could mediate the residual kidney regeneration and thus improve disturbed renal function after partial nephrectomy. However, the cellular changes including the angiogenesis in the implanted DC scaffold has not yet been elaborated. In this study, we observed that the scaffold promoted the proliferation of human umbilical vein endothelial cells (HUVEC) that adhered to the DC scaffold in vitro. We next examined the pathological changes of the implanted DC graft in vivo, and found a decreased volume of the scaffold and a dramatic angiogenesis within the scaffold. The average microvessel density (aMVD) increased at the early stage, while decreased at the later stage post transplantation. Expression level of vascular endothelial growth factor (VEGF) showed similar dynamic changes. In addition, many endothelial cells (ECs) and endothelial progenitor cells (EPCs) were distributed in the region which contained active angiogenesis in the scaffold. However, the implanted graft became fibrosis and the angiogenesis degraded at final stage roughly 8 weeks post transplantation. Our data indicate that DC scaffold can be vascularized in vivo and possible mechanisms are discussed. PMID:27058889

  5. The Alginate Demonstration: Polymers, Food Science, and Ion Exchange

    NASA Astrophysics Data System (ADS)

    Waldman, Amy Sue; Schechinger, Linda; Govindarajoo, Geeta; Nowick, James S.; Pignolet, Louis H.

    1998-11-01

    We have recently devised a polymer demonstration involving the crosslinking and decrosslinking of alginate, a polysaccharide isolated from seaweed. The polymer is composed of D-mannuronic acid and L-guluronic acid subunits and is a component of cell walls. It is commonly used as a thickener in foods such as ice cream and fruit-filled snacks. For the demonstration, a 2% solution of sodium alginate is poured into a 1% solution of calcium chloride. Nontoxic calcium alginate "worms" form due to crosslinking of the polymer. Alternatively, the commercially available antacid Gaviscon can be used as a source of sodium alginate. The crosslinks can then be broken by shaking the worms in brine. The demonstration is a fine addition to any chemical educator's repertoire of polymer experiments.

  6. Enzyme-entrapping behaviors in alginate fibers and their papers

    SciTech Connect

    Kobayashi, Y.; Matsuo, R.; Ohya, T.; Yokoi, N.

    1987-01-01

    Enzyme immobilization in the form of fiber and paper was easily achieved by wet spinning of aqueous admixture of sodium alginate and enzymes into divalent metallic ion solution as a coagulating bath, followed by paper making of resultant shortly cut fibers. Entrapment yields of enzymes used, e.g., glucoamylase, cyclodextrin glucanotransferase, endo-polygalacturonase, and protease, were always higher in calcium alginate fibers and their papers than those in corresponding beads. It was found that the yields increased with an increase of the discharge rate through the spinning nozzle because the higher discharge rate could provide more highly oriented metal-chelate linear polymer molecules along the fiber axis for preventing leakage of entrapped enzymes. Divalent metallic ions affected greatly the entrapment of glucoamylase in alginate fibers, the order of which followed rougly the ionotropic series of Thiele. Entrapment of glucoamylase in bicomponent systems comprising alginate and other water-soluble polymers was also investigated. (Refs. 41).

  7. Modified alginate and chitosan for lactic acid bacteria immobilization.

    PubMed

    Le-Tien, Canh; Millette, Mathieu; Mateescu, Mircea-Alexandru; Lacroix, Monique

    2004-06-01

    Beads with enhanced-stability acid media, which were based on alginate and chitosan functionalized by succinylation (increasing the anionic charges able to retain protons) or by acylation (improving matrix hydrophobicity), were developed for immobilization of bacterial cells. Beads (3 mm diameter) formed by ionotropic gelation with CaCl(2) presented good mechanical characteristics. After 30 min incubation of viable free Lactobacillus rhamnosus cells in simulated gastric fluid (pH 1.5), we noticed that the level of viable bacteria was undetectable. Bacterial immobilization in native-alginate-based beads generated a viable-cell count of 22-26%, whereas, when entrapped in succinylated alginate and chitosan beads, the percentage of viable cells was of 60 and 66%, respectively. Best viability (87%) was found for bacteria immobilized in N -palmitoylaminoethyl alginate, which affords a high protective effect, probably due to long alkyl pendants that improve the beads' hydrophobicity, limiting hydration in the acidic environment.

  8. Characterization of morphology and composition of inorganic fillers in dental alginates.

    PubMed

    Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

    2014-01-01

    Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450(°)C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C-81.59%, H-79.89%, O-78.87%, H5-77.95%, JP-66.88%, wt). The filler fractions in volume (vt) were as follows: H5-84.85%, JP-74.76%, H-70.03%, O-68.31%, and C-56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

  9. Flicking technique for microencapsulation of cells in calcium alginate leading to the microtissue formation.

    PubMed

    Wong, Soon Chuan; Soon, Chin Fhong; Leong, Wai Yean; Tee, Kian Sek

    2016-01-01

    Microbeads have wide applications in biomedical engineering field that include drug delivery, encapsulation of biomolecules, tissue padding and tissue regeneration. In this paper, we report a simple, yet efficient, flicking technique to produce microcapsules of calcium alginate at a narrow distribution of size. The system consists of an infusion pump and a customised flicker that taps the syringe needle for dispersing microcapsules of sodium alginate that polymerised in the calcium chloride solution. The flow rate of the syringe pump and the velocity of the flicker were studied to achieve a well controlled and tunable size distribution of microbeads ranging from 200 to 400 μm. At a flow rate of 4 μl/min and flicking rate of 80 rpm, a narrow size distribution of microbeads were produced. Via this technique, HaCaT cells were encapsulated in calcium alginate microbeads that grown into microtissues with a size ranging from 100 to 300 μm after two weeks of culture. These microtissues could be potentially useful for pharmacological application. PMID:26878098

  10. Production of polyhydroxybutyrate and alginate from glycerol by Azotobacter vinelandii under nitrogen-free conditions.

    PubMed

    Yoneyama, Fuminori; Yamamoto, Mayumi; Hashimoto, Wataru; Murata, Kousaku

    2015-01-01

    Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-d-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including γ-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source. PMID:25880041

  11. Production of polyhydroxybutyrate and alginate from glycerol by Azotobacter vinelandii under nitrogen-free conditions

    PubMed Central

    Yoneyama, Fuminori; Yamamoto, Mayumi; Hashimoto, Wataru; Murata, Kousaku

    2015-01-01

    Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-d-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including γ-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source. PMID:25880041

  12. A comprehensive approach to in vitro functional evaluation of Ag/alginate nanocomposite hydrogels.

    PubMed

    Stojkovska, Jasmina; Kostić, Danijela; Jovanović, Željka; Vukašinović-Sekulić, Maja; Mišković-Stanković, Vesna; Obradović, Bojana

    2014-10-13

    In this work, we present a comprehensive approach to evaluation of alginate microbeads with included silver nanoparticles (AgNPs) at the concentration range of 0.3-5mM for potential biomedical use by combining cytotoxicity, antibacterial activity, and silver release studies. The microbeads were investigated regarding drying and rehydration showing retention of ∼ 80-85% of the initial nanoparticles as determined by UV-vis and SEM analyses. Both wet and dry microbeads were shown to release AgNPs and/or ions inducing similar growth delays of Staphylococcus aureus and Escherichia coli at the total released silver concentrations of ∼ 10 μg/ml. On the other hand, these concentrations were highly toxic for bovine chondrocytes in conventional monolayer cultures while nontoxic when cultured in alginate microbeads under biomimetic conditions in 3D perfusion bioreactors. The applied approach outlined directions for further optimization studies demonstrating Ag/alginate microbeads as potentially attractive components of soft tissue implants as well as antimicrobial wound dressings.

  13. Modified alginate beads for mucoadhesive drug delivery system: an updated review of patents.

    PubMed

    Swain, Suryakanta; Behera, Aurobinda; Beg, Sarwar; Patra, Chinam N; Dinda, Subash C; Sruti, Jammula; Rao, Muddana E B

    2012-12-01

    Pharmaceutical research and inventions are increasingly developed for the design of an ideal dosage regimen in drug therapy of many diseases, which attains therapeutic concentration of drug in plasma and maintains it constant for the entire duration of treatment and also minimizes the side effects. Recent trends in pharmaceutical technology indicated that mucoadhesive micro particle and modified alginate beads as drug delivery system especially suitable for achieving delivery of drug in a predetermined rate locally or systemically for a prolonged period of time. The release of drug from microparticle depends on a variety of factors including carrier used to form the micro particle and amount of drug contained in them. The main aim of the present review is to explain the various theories, mechanisms, advanced mucoadhesive polymers, various delivery approaches, methodologies for developing a mucoadhesive micro-particle and modified alginate beads formulation, in vitro, ex vivo and in vivo characterization. Apart from this, an innovative test method that is biacore is highlighted in this review to measure the mucoadhesive strength. This review is also briefly explained about the updated patenting system for the development of micro-particle and modified alginate beads as drug delivery system.

  14. Synthesis and evaluation of hydroponically alginate nanoparticles as novel carrier for intravenous delivery of propofol.

    PubMed

    Najafabadi, Alireza Hassani; Azodi-Deilami, Saman; Abdouss, Majid; Payravand, Hamid; Farzaneh, Sina

    2015-03-01

    Commercial lipid emulsion of propofol (CLE) has several drawbacks including pain on injection and emulsion instability. In this paper, a novel nanocarrier system is introduced to improve stability and solubility of the poorly soluble anesthetic drug, propofol, for intravenous administration. In this paper, alginate is modified using a facile method in which the carboxylic group of alginate is grafted to octanol. The octanol-grafted alginate (Alg-C8) is then employed to prepare nanoparticles which are subsequently used for encapsulation of propofol. The nanoparticles are analyzed for their pH, osmolarity, particle size, stability, morphology and sleep recovery and the results are compared with CLE as control. It is revealed that nanoparticles have the average particle size of 180 nm ± 1.2 and spherical morphology which is less than CLE while their pH, osmolarity and profile of release of formulated nanoparticles are similar to those of CLE. In addition, the results show good chemical and physical storage stability for the nanoparticles at room temperature for at least 6 months compared to CLE as control. The animal sleep recovery test on rats shows no significant difference in time of unconsciousness and recovery of the righting reflex between nanoparticles and CLE. It is concluded that encapsulated nanoparticles introduced here could be a promising clinical intravenous system for delivery of poorly soluble anesthetic propofol. In addition, this study provides an efficient and facile method for preparing a carrier system for water insoluble drugs.

  15. pH-dependent release property of alginate beads containing calcium carbonate particles.

    PubMed

    Han, M R; Kwon, M C; Lee, H Y; Kim, J C; Kim, J D; Yoo, S K; Sin, I S; Kim, S M

    2007-12-01

    Alginate bead containing calcium carbonate particle were prepared by dropping the suspension of alginate/calcium carbonate (4/1, w/w) into aqueous solution of CaCl(2) (0.1 M). The pH-dependent release property of the bead was observed for 12 h using blue dextran as a model drug. The release increased up to 4 h in a saturation manner. When no calcium carbonate was contained, the release exhibited no marked variation with pH and the values were 27-39%. On the other hand, in case calcium carbonate was included in the matrix of alginate beads, intensive release(40-50%) was achieved in acidic and neutral conditions and the degrees of release were suppressed in alkali conditions and the values were approximately 20%. The pH-sensitive release property is possibly because the particles of calcium carbonate embedded in the matrix of beads were leached out in acidic and neutral conditions, leaving cavities in the matrix. The cavities are likely to be main pathways for the release of blue dextran.

  16. A simple, quantitative method using alginate gel to determine rat colonic tumor volume in vivo.

    PubMed

    Irving, Amy A; Young, Lindsay B; Pleiman, Jennifer K; Konrath, Michael J; Marzella, Blake; Nonte, Michael; Cacciatore, Justin; Ford, Madeline R; Clipson, Linda; Amos-Landgraf, James M; Dove, William F

    2014-04-01

    Many studies of the response of colonic tumors to therapeutics use tumor multiplicity as the endpoint to determine the effectiveness of the agent. These studies can be greatly enhanced by accurate measurements of tumor volume. Here we present a quantitative method to easily and accurately determine colonic tumor volume. This approach uses a biocompatible alginate to create a negative mold of a tumor-bearing colon; this mold is then used to make positive casts of dental stone that replicate the shape of each original tumor. The weight of the dental stone cast correlates highly with the weight of the dissected tumors. After refinement of the technique, overall error in tumor volume was 16.9% ± 7.9% and includes error from both the alginate and dental stone procedures. Because this technique is limited to molding of tumors in the colon, we utilized the Apc(Pirc/+) rat, which has a propensity for developing colonic tumors that reflect the location of the majority of human intestinal tumors. We have successfully used the described method to determine tumor volumes ranging from 4 to 196 mm³. Alginate molding combined with dental stone casting is a facile method for determining tumor volume in vivo without costly equipment or knowledge of analytic software. This broadly accessible method creates the opportunity to objectively study colonic tumors over time in living animals in conjunction with other experiments and without transferring animals from the facility where they are maintained.

  17. Overcoming drug resistance with alginate oligosaccharides able to potentiate the action of selected antibiotics.

    PubMed

    Khan, Saira; Tøndervik, Anne; Sletta, Håvard; Klinkenberg, Geir; Emanuel, Charlotte; Onsøyen, Edvar; Myrvold, Rolf; Howe, Robin A; Walsh, Timothy R; Hill, Katja E; Thomas, David W

    2012-10-01

    The uncontrolled, often inappropriate use of antibiotics has resulted in the increasing prevalence of antibiotic-resistant pathogens, with major cost implications for both United States and European health care systems. We describe the utilization of a low-molecular-weight oligosaccharide nanomedicine (OligoG), based on the biopolymer alginate, which is able to perturb multidrug-resistant (MDR) bacteria by modulating biofilm formation and persistence and reducing resistance to antibiotic treatment, as evident using conventional and robotic MIC screening and microscopic analyses of biofilm structure. OligoG increased (up to 512-fold) the efficacy of conventional antibiotics against important MDR pathogens, including Pseudomonas, Acinetobacter, and Burkholderia spp., appearing to be effective with several classes of antibiotic (i.e., macrolides, β-lactams, and tetracyclines). Using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), increasing concentrations (2%, 6%, and 10%) of alginate oligomer were shown to have a direct effect on the quality of the biofilms produced and on the health of the cells within that biofilm. Biofilm growth was visibly weakened in the presence of 10% OligoG, as seen by decreased biomass and increased intercellular spaces, with the bacterial cells themselves becoming distorted and uneven due to apparently damaged cell membranes. This report demonstrates the feasibility of reducing the tolerance of wound biofilms to antibiotics with the use of specific alginate preparations.

  18. Characterization of Morphology and Composition of Inorganic Fillers in Dental Alginates

    PubMed Central

    Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

    2014-01-01

    Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450°C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C—81.59%, H—79.89%, O—78.87%, H5—77.95%, JP—66.88%, wt). The filler fractions in volume (vt) were as follows: H5—84.85%, JP—74.76%, H—70.03%, O—68.31%, and C—56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

  19. Ultrasoft Alginate Hydrogels Support Long-Term Three-Dimensional Functional Neuronal Networks.

    PubMed

    Palazzolo, Gemma; Broguiere, Nicolas; Cenciarelli, Orlando; Dermutz, Harald; Zenobi-Wong, Marcy

    2015-08-01

    Neuron development and function are exquisitely sensitive to the mechanical properties of their surroundings. Three-dimensional (3D) cultures are therefore being explored as they better mimic the features of the native extracellular matrix. Limitations of existing 3D culture models include poorly defined composition, rapid degradation, and suboptimal biocompatibility. Here we show that ionically cross-linked ultrasoft hydrogels made from unmodified alginate can potently promote neuritogenesis. Alginate hydrogels were characterized mechanically and a remarkable range of stiffness (10-4000 Pa) could be produced by varying the macromer content (0.1-0.4% w/v) and CaCl2 concentration. Dissociated rat embryonic cortical neurons encapsulated within the softest of the hydrogels (0.1% w/v, 10 mM CaCl2) showed excellent viability, extensive formation of axons and dendrites, and long-term activity as determined by calcium imaging. In conclusion, alginate is an off-the-shelf, easy to handle, and inexpensive material, which can be used to make ultrasoft hydrogels for the formation of stable and functional 3D neuronal networks. This 3D culture system could have important applications in neuropharmacology, toxicology, and regenerative medicine.

  20. Psychrotrophic Streptomyces spp. cells immobilisation in alginate microspheres produced by emulsification-internal gelation.

    PubMed

    Cotârleţ, Mihaela; Dima, Stefan; Bahrim, Gabriela

    2014-01-01

    The objective of the investigations was the optimisation of the parameters for cold-adapted Streptomyces MIUG 4 Alga strain cells immobilisation using emulsification-internal gelation technique in calcium alginate microspheres and testing their ability to produce cold-active β-amylase. By Box-Behnken design and response surface methodology, the effects of independent variables were established, which included sodium alginate concentration (A), sodium alginate:living cell ratio (B) and the Span 80 concentration (C) upon microspheres formation and their functionality. Mean diameter of formed microspheres with immobilised biomass and cold-active β-amylase production were chosen as dependent variables in order to increase the yield of starch hydrolysis. Diameters of microspheres <25.5 μm provided large yield of cold-active β-amylase comparing with microspheres with bigger diameter. A 1.5-fold increase in the substrate hydrolysis yield was achieved using the immobilised biocatalyst compared with the crude enzyme extract, after 96 h of substrate bioconversion.

  1. A Simple, Quantitative Method Using Alginate Gel to Determine Rat Colonic Tumor Volume In Vivo

    PubMed Central

    Irving, Amy A; Young, Lindsay B; Pleiman, Jennifer K; Konrath, Michael J; Marzella, Blake; Nonte, Michael; Cacciatore, Justin; Ford, Madeline R; Clipson, Linda; Amos-Landgraf, James M; Dove, William F

    2014-01-01

    Many studies of the response of colonic tumors to therapeutics use tumor multiplicity as the endpoint to determine the effectiveness of the agent. These studies can be greatly enhanced by accurate measurements of tumor volume. Here we present a quantitative method to easily and accurately determine colonic tumor volume. This approach uses a biocompatible alginate to create a negative mold of a tumor-bearing colon; this mold is then used to make positive casts of dental stone that replicate the shape of each original tumor. The weight of the dental stone cast correlates highly with the weight of the dissected tumors. After refinement of the technique, overall error in tumor volume was 16.9% ± 7.9% and includes error from both the alginate and dental stone procedures. Because this technique is limited to molding of tumors in the colon, we utilized the ApcPirc/+ rat, which has a propensity for developing colonic tumors that reflect the location of the majority of human intestinal tumors. We have successfully used the described method to determine tumor volumes ranging from 4 to 196 mm3. Alginate molding combined with dental stone casting is a facile method for determining tumor volume in vivo without costly equipment or knowledge of analytic software. This broadly accessible method creates the opportunity to objectively study colonic tumors over time in living animals in conjunction with other experiments and without transferring animals from the facility where they are maintained. PMID:24674588

  2. Calcium phosphate-alginate microspheres as enzyme delivery matrices.

    PubMed

    Ribeiro, C C; Barrias, C C; Barbosa, M A

    2004-08-01

    The present study concerns the preparation and initial characterisation of novel calcium titanium phosphate-alginate (CTP-alginate) and hydroxyapatite-alginate (HAp-alginate) microspheres, which are intended to be used as enzyme delivery matrices and bone regeneration templates. Microspheres were prepared using different concentrations of polymer solution (1% and 3% w/v) and different ceramic-to-polymer solution ratios (0.1, 0.2 and 0.4 w/w). Ceramic powders were characterised using X-ray diffraction, laser granulometry, Brunauer, Emmel and Teller (BET) method for the determination of surface area, zeta potential and Fourier transform infrared spectroscopy (FT-IR). Alginate was characterised using high performance size exclusion chromatography. The methodology followed in this investigation enabled the preparation of homogeneous microspheres with a uniform size. Studies on the immobilisation and release of the therapeutic enzyme glucocerebrosidase, employed in the treatment of Gaucher disease, were also performed. The enzyme was incorporated into the ceramic-alginate matrix before gel formation in two different ways: pre-adsorbed onto the ceramic particles or dispersed in the polymeric matrix. The two strategies resulted in distinct release profiles. Slow release was obtained after adsorption of the enzyme to the ceramic powders, prior to preparation of the microspheres. An initial fast release was achieved when the enzyme and the ceramic particles were dispersed in the alginate solution before producing the microspheres. The latter profile is very similar to that of alginate microspheres. The different patterns of enzyme release increase the range of possible applications of the system investigated in this work.

  3. Nanocellulose-alginate hydrogel for cell encapsulation.

    PubMed

    Park, Minsung; Lee, Dajung; Hyun, Jinho

    2015-02-13

    TEMPO-oxidized bacterial cellulose (TOBC)-sodium alginate (SA) composites were prepared to improve the properties of hydrogel for cell encapsulation. TOBC fibers were obtained using a TEMPO/NaBr/NaClO system at pH 10 and room temperature. The fibrillated TOBCs mixed with SA were cross-linked in the presence of Ca(2+) solution to form hydrogel composites. The compression strength and chemical stability of the TOBC/SA composites were increased compared with the SA hydrogel, which indicated that TOBC performed an important function in enhancing the structural, mechanical and chemical stability of the composites. Cells were successfully encapsulated in the TOBC/SA composites, and the viability of cells was investigated. TOBC/SA composites can be a potential candidate for cell encapsulation engineering. PMID:25458293

  4. Viscoelastic properties of mineralized alginate hydrogel beads.

    PubMed

    Olderøy, Magnus O; Xie, Minli; Andreassen, Jens-Petter; Strand, Berit L; Zhang, Zhibing; Sikorski, Pawel

    2012-07-01

    Alginate hydrogels have applications in biomedicine, ranging from delivery of cells and growth factors to wound management aids. However, they are mechanically soft and have shown little potential for the use in bone tissue engineering. Here, the viscoelastic properties of alginate hydrogel beads mineralized with calcium phosphate, both by a counter-diffusion (CD) and an enzymatic approach, are characterized by a micro-manipulation technique and mathematical modeling. Fabricated hydrogel materials have low mineral content (below 3 % of the total hydrogel mass, which corresponds to mineral content of up to 60 % of the dry mass) and low dry mass content (<5 %). For all samples compression and hold (relaxation after compression) data was collected and analyzed. The apparent Young's modulus of the mineralized beads was estimated by the Hertz model (compression data) and was shown to increase up to threefold upon mineralization. The enzymatically mineralized beads showed higher apparent Young's modulus compared to the ones mineralized by CD, even though the mineral content of the former was lower. Full compression-relaxation force-time profiles were analyzed using viscoelastic model. From this analysis, infinite and instantaneous Young's moduli were determined. Similarly, enzymatic mineralized beads, showed higher instantaneous and infinite Young's modulus, even if the degree of mineralization is lower then that achieved for CD method. This leads to the conclusion that both the degree of mineralization and the spatial distribution of mineral are important for the mechanical performance of the composite beads, which is in analogy to highly structured mineralized tissues found in many organisms.

  5. Microfluidic generation of hollow Ca-alginate microfibers.

    PubMed

    Meng, Zhi-Jun; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2016-07-01

    This work reports on an efficient microfluidic approach for continuous production of hollow Ca-alginate microfibers with controllable structures and functions. A coaxial microcapillary microfluidic device combined with a rotator is constructed to produce a cylindrical flow jet with four aqueous solutions as templates for continuous fabrication and collection of microfibers. A four-aqueous-phase flow jet with an intermediate buffer flow between the Ca(2+)-containing and alginate-containing flows is used as the template for microfiber fabrication. The buffer flow efficiently controls the diffusion of Ca(2+) into the alginate-containing flow as well as the crosslinking reaction, thus ensuring the continuous fabrication of hollow Ca-alginate microfibers under relatively low flow rates without clogging of the microchannel. The structure of the hollow microfibers can be flexibly adjusted by changing the flow rates and device dimensions. Meanwhile, the continuous fabrication process of the microfibers allows flexible incorporation of a functional component into the sheath flow for functionalization and addition of active substances in the core flow for encapsulation. This is demonstrated by fabricating hollow Ca-alginate microfibers with a wall containing magnetic nanoparticles for magnetic functionalization and with hollow internals containing Chlorella pyrenoidosa cells for confined growth. This work provides an efficient strategy for continuous fabrication of functional hollow Ca-alginate microfibers with controllable structures and functions.

  6. Microfluidic generation of hollow Ca-alginate microfibers.

    PubMed

    Meng, Zhi-Jun; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2016-07-01

    This work reports on an efficient microfluidic approach for continuous production of hollow Ca-alginate microfibers with controllable structures and functions. A coaxial microcapillary microfluidic device combined with a rotator is constructed to produce a cylindrical flow jet with four aqueous solutions as templates for continuous fabrication and collection of microfibers. A four-aqueous-phase flow jet with an intermediate buffer flow between the Ca(2+)-containing and alginate-containing flows is used as the template for microfiber fabrication. The buffer flow efficiently controls the diffusion of Ca(2+) into the alginate-containing flow as well as the crosslinking reaction, thus ensuring the continuous fabrication of hollow Ca-alginate microfibers under relatively low flow rates without clogging of the microchannel. The structure of the hollow microfibers can be flexibly adjusted by changing the flow rates and device dimensions. Meanwhile, the continuous fabrication process of the microfibers allows flexible incorporation of a functional component into the sheath flow for functionalization and addition of active substances in the core flow for encapsulation. This is demonstrated by fabricating hollow Ca-alginate microfibers with a wall containing magnetic nanoparticles for magnetic functionalization and with hollow internals containing Chlorella pyrenoidosa cells for confined growth. This work provides an efficient strategy for continuous fabrication of functional hollow Ca-alginate microfibers with controllable structures and functions. PMID:27302737

  7. Sodium alginate decreases the permeability of intestinal mucus

    PubMed Central

    Mackie, Alan R.; Macierzanka, Adam; Aarak, Kristi; Rigby, Neil M.; Parker, Roger; Channell, Guy A.; Harding, Stephen E.; Bajka, Balazs H.

    2016-01-01

    In the small intestine the nature of the environment leads to a highly heterogeneous mucus layer primarily composed of the MUC2 mucin. We set out to investigate whether the soluble dietary fibre sodium alginate could alter the permeability of the mucus layer. The alginate was shown to freely diffuse into the mucus and to have minimal effect on the bulk rheology when added at concentrations below 0.1%. Despite this lack of interaction between the mucin and alginate, the addition of alginate had a marked effect on the diffusion of 500 nm probe particles, which decreased as a function of increasing alginate concentration. Finally, we passed a protein stabilised emulsion through a simulation of oral, gastric and small intestinal digestion. We subsequently showed that the addition of 0.1% alginate to porcine intestinal mucus decreased the diffusion of fluorescently labelled lipid present in the emulsion digesta. This reduction may be sufficient to reduce problems associated with high rates of lipid absorption such as hyperlipidaemia. PMID:26726279

  8. Encapsulation of fibroblasts causes accelerated alginate hydrogel degradation.

    PubMed

    Hunt, N C; Smith, A M; Gbureck, U; Shelton, R M; Grover, L M

    2010-09-01

    Calcium-alginate hydrogel has been widely studied as a material for cell encapsulation for tissue engineering. At present, the effect that cells have on the degradation of alginate hydrogel is largely unknown. We have shown that fibroblasts encapsulated at a density of 7.5 x 10(5) cells ml(-1) in both 2% and 5% w/v alginate remain viable for at least 60 days. Rheological analysis was used to study how the mechanical properties exhibited by alginate hydrogel changed during 28 days in vitro culture. Alginate degradation was shown to occur throughout the study but was greatest within the first 7 days of culture for all samples, which correlated with a sharp release of calcium ions from the construct. Fibroblasts were shown to increase the rate of degradation during the first 7 days when compared with acellular samples in both 2% and 5% w/v gels, but after 28 days both acellular and cell-encapsulating samples retained disc-shaped morphologies and gel-like spectra. The results demonstrate that although at an early stage cells influence the mechanical properties of encapsulating alginate, over a longer period of culture, the hydrogels retain sufficient mechanical integrity to exhibit gel-like properties. This allows sustained immobilization of the cells at the desired location in vivo where they can produce extracellular matrix and growth factors to expedite the healing process.

  9. Novel alginate based nanocomposite hydrogels with incorporated silver nanoparticles.

    PubMed

    Obradovic, Bojana; Stojkovska, Jasmina; Jovanovic, Zeljka; Miskovic-Stankovic, Vesna

    2012-01-01

    Alginate colloid solution containing electrochemically synthesized silver nanoparticles (AgNPs) was investigated regarding the nanoparticle stabilization and possibilities for production of alginate based nanocomposite hydrogels in different forms. AgNPs were shown to continue to grow in alginate solutions for additional 3 days after the synthesis by aggregative mechanism and Ostwald ripening. Thereafter, the colloid solution remains stable for 30 days and could be used alone or in mixtures with aqueous solutions of poly(vinyl alcohol) (PVA) and poly(N-vinyl-2-pyrrolidone) (PVP) while preserving AgNPs as verified by UV-Vis spectroscopy studies. We have optimized techniques for production of Ag/alginate microbeads and Ag/alginate/PVA beads, which were shown to efficiently release AgNPs decreasing the Escherichia coli concentration in suspensions for 99.9% over 24 h. Furthermore, Ag/hydrogel discs based on alginate, PVA and PVP were produced by freezing-thawing technique allowing adjustments of hydrogel composition and mechanical properties as demonstrated in compression studies performed in a biomimetic bioreactor. PMID:22203513

  10. A Pseudomonas aeruginosa alginate-exotoxin A conjugate that elicits anti-alginate and exotoxin A-neutralizing antibodies.

    PubMed

    Coin, D; Vacheron, M J; Guinand, M; Michel, G

    1991-08-01

    Pseudomonas aeruginosa alginate was covalently coupled to exotoxin A by reductive amination using adipic acid dihydrazide as spacer. The conjugate was composed of 25% alginate and 75% exotoxin A and possessed an average molecular mass higher than 700 kDa as determined by polyacrylamide gel electrophoresis. The conjugate had virtually no ADP-ribosyltransferase activity and a reduced cytotoxicity for TSA8 murine cells, derived from Friend erythroleukemia cells, as indicated by a greater than 50-fold increased LD50. Anti-conjugate antibodies recognized exotoxin A and alginate. A booster injection resulted in markedly increased antibody ELISA titers to both exotoxin A and alginate. The antibodies neutralized the exotoxin A toxicity. PMID:1931130

  11. Study of the interpolyelectrolyte reaction between chitosan and alginate: influence of alginate composition and chitosan molecular weight.

    PubMed

    Becherán-Marón, L; Peniche, C; Argüelles-Monal, W

    2004-04-01

    The interpolyelectrolyte reaction between chitosan (CHI) and alginate (ALG) was followed by conductimetry and potentiometry. Five chitosan samples, all with almost the same degree of N-acetylation (DA approximately 0.20) and molecular weights ranging from 5 x 10(3) to 2.5 x 10(5) Da were used. The polyelectrolyte complex was formed using alginate samples with three different M/G values (0.44, 1.31 and 1.96). The composition of the complex, Z (Z = [CHI]/[ALG]) resulted 0.70 +/- 0.02, independently of the molecular weight of chitosan and the composition of the alginate used. The degree of complexation was 0.51 with no dependence on the alginate composition.

  12. Clinical applications of naturally derived biopolymer-based scaffolds for regenerative medicine.

    PubMed

    Stoppel, Whitney L; Ghezzi, Chiara E; McNamara, Stephanie L; Black, Lauren D; Kaplan, David L

    2015-03-01

    Naturally derived polymeric biomaterials, such as collagens, silks, elastins, alginates, and fibrins are utilized in tissue engineering due to their biocompatibility, bioactivity, and tunable mechanical and degradation kinetics. The use of these natural biopolymers in biomedical applications is advantageous because they do not release cytotoxic degradation products, are often processed using environmentally-friendly aqueous-based methods, and their degradation rates within biological systems can be manipulated by modifying the starting formulation or processing conditions. For these reasons, many recent in vivo investigations and FDA-approval of new biomaterials for clinical use have utilized natural biopolymers as matrices for cell delivery and as scaffolds for cell-free support of native tissues. This review highlights biopolymer-based scaffolds used in clinical applications for the regeneration and repair of native tissues, with a focus on bone, skeletal muscle, peripheral nerve, cardiac muscle, and cornea substitutes.

  13. Composite three-dimensional woven scaffolds with interpenetrating network hydrogels to create functional synthetic articular cartilage.

    PubMed

    Liao, I-Chien; Moutos, Franklin T; Estes, Bradley T; Zhao, Xuanhe; Guilak, Farshid

    2013-12-17

    The development of synthetic biomaterials that possess mechanical properties that mimic those of native tissues remains an important challenge to the field of materials. In particular, articular cartilage is a complex nonlinear, viscoelastic, and anisotropic material that exhibits a very low coefficient of friction, allowing it to withstand millions of cycles of joint loading over decades of wear. Here we show that a three-dimensionally woven fiber scaffold that is infiltrated with an interpenetrating network hydrogel can provide a functional biomaterial that provides the load-bearing and tribological properties of native cartilage. An interpenetrating dual-network "tough-gel" consisting of alginate and polyacrylamide was infused into a porous three-dimensionally woven poly(ε-caprolactone) fiber scaffold, providing a versatile fiber-reinforced composite structure as a potential acellular or cell-based replacement for cartilage repair. PMID:24578679

  14. Composite three-dimensional woven scaffolds with interpenetrating network hydrogels to create functional synthetic articular cartilage.

    PubMed

    Liao, I-Chien; Moutos, Franklin T; Estes, Bradley T; Zhao, Xuanhe; Guilak, Farshid

    2013-12-17

    The development of synthetic biomaterials that possess mechanical properties that mimic those of native tissues remains an important challenge to the field of materials. In particular, articular cartilage is a complex nonlinear, viscoelastic, and anisotropic material that exhibits a very low coefficient of friction, allowing it to withstand millions of cycles of joint loading over decades of wear. Here we show that a three-dimensionally woven fiber scaffold that is infiltrated with an interpenetrating network hydrogel can provide a functional biomaterial that provides the load-bearing and tribological properties of native cartilage. An interpenetrating dual-network "tough-gel" consisting of alginate and polyacrylamide was infused into a porous three-dimensionally woven poly(ε-caprolactone) fiber scaffold, providing a versatile fiber-reinforced composite structure as a potential acellular or cell-based replacement for cartilage repair.

  15. Design of a bioresorbable polymeric scaffold for osteoblast culture

    NASA Astrophysics Data System (ADS)

    Ditaranto, Vincent M., Jr.

    Bioresorbable polymeric scaffolds were designed for the purpose of growing rat osteosarcoma cells (ROS 17/2.8) using the compression molding method. The material used in the construction of the scaffolds was a mixture of polycaprolactone (PCL), Hydroxyapatite (HA), Glycerin (GL) and salt (NaCl) for porosity. The concentration of the several materials utilized, was determined by volume. Past research at the University of Massachusetts Lowell (UML) has successfully utilized the compression molding method for the construction of scaffolds, but was unable to accomplish the goal of long term cell survival and complete cellular proliferation throughout a three dimensional scaffold. This research investigated various concentrations of the materials and molding temperatures used for the manufacture of scaffolds in order to improve the scaffold design and address those issues. The design of the scaffold using the compression molding process is detailed in the Method and Materials section of this thesis. The porogen (salt) used for porosity was suspected as a possible source of contamination causing cell apoptosis in past studies. This research addressed the issues for cell survival and proliferation throughout a three dimensional scaffold. The leaching of the salt was one major design modification. This research successfully used ultrasonic leaching in addition to the passive method. Prior to cell culture, the scaffolds were irradiated to 2.75 Mrad, with cobalt-60 gamma radionuclide. The tissue culture consisted of two trials: (1) cell culture in scaffolds cleaned with passive leaching; (2) cell culture with scaffolds cleaned with ultrasonic leaching. Cell survival and proliferation was accomplished only with the addition of ultrasonic leaching of the scaffolds. Analysis of the scaffolds included Scanning Electron Microscopy (SEM), Nikon light microscopy and x-ray mapping of the calcium, sodium and chloride ion distribution. The cells were analyzed by Environmental Scanning

  16. Determination of diffusion coefficients and diffusion characteristics for chlorferon and diethylthiophosphate in Ca-alginate gel beads.

    PubMed

    Ha, Jiyeon; Engler, Cady R; Lee, Seung Jae

    2008-07-01

    Diffusion characteristics of chlorferon and diethylthiophosphate (DETP) in Ca-alginate gel beads were studied to assist in designing and operating bioreactor systems. Diffusion coefficients for chlorferon and DETP in Ca-alginate gel beads determined at conditions suitable for biodegradation studies were 2.70 x 10(-11) m(2)/s and 4.28 x 10(-11) m(2)/s, respectively. Diffusivities of chlorferon and DETP were influenced by several factors, including viscosity of the bulk solution, agitation speed, and the concentrations of diffusing substrate and immobilized cells. Diffusion coefficients increased with increasing agitation speed, probably due to poor mixing at low speed and some attrition of beads at high speeds. Diffusion coefficients also increased with decreasing substrate concentration. Increased cell concentration in the gel beads caused lower diffusivity. Theoretical models to predict diffusivities as a function of cell weight fraction overestimated the effective diffusivities for both chlorferon and DETP, but linear relations between effective diffusivity and cell weight fraction were derived from experimental data. Calcium-alginate gel beads with radii of 1.65-1.70 mm used in this study were not subject to diffusional limitations: external mass transfer resistances were negligible based on Biot number calculations and effectiveness factors indicated that internal mass transfer resistance was negligible. Therefore, the degradation rates of chlorferon and DETP inside Ca-alginate gel beads were reaction-limited. PMID:18080347

  17. Ceramic scaffolds enriched with gentamicin loaded poly(lactide-co-glycolide) microparticles for prevention and treatment of bone tissue infections.

    PubMed

    Rumian, Łucja; Tiainen, Hanna; Cibor, Urszula; Krok-Borkowicz, Małgorzata; Brzychczy-Włoch, Monika; Haugen, Håvard J; Pamuła, Elżbieta

    2016-12-01

    Bone scaffolds are susceptible for bacterial infection when implanted, particularly in compromised bone. Therefore anti-bacterial bone scaffolds are desirable. Here a novel approach to provide bactericidal properties for titanium dioxide scaffolds is proposed. Gentamicin loaded poly(L-lactide-co-glycolide) microparticles were immobilized on the scaffold pore walls by sodium alginate hydrogel. The results show that the microparticles were effectively immobilized on the scaffolds. Desired burst release was observed within the first 8h and gentamicin dose reached 125μg from single scaffold that corresponded to ~25% of total drug introduced in the system. Following the initial burst, the dose was gradually decreasing up to day 10 and afterwards a sustained release of 3μg/day was measured. Cumulatively ~90% of the drug was delivered up to day 50. Above pattern, i.e. burst release with following sustained release, is desired for prevention of perioperative bone infections: burst release stops local infections during post-implantation "decisive period" while further sustained drug release prevents bacterial recolonization. In vitro studies confirmed antimicrobial activity of released gentamicin against Staphylococcus spp. and cytocompatibility of the system with osteoblast-like cells (MG-63). Thus the system is a viable option for the treatment of bone tissue defects. PMID:27612780

  18. Influence of various alginate brands on the redifferentiation of dedifferentiated bovine articular chondrocytes in alginate bead culture under high and low oxygen tension.

    PubMed

    Domm, C; Schünke, M; Steinhagen, J; Freitag, S; Kurz, B

    2004-01-01

    We examined the influence of various alginates on the redifferentiation of dedifferentiated articular chondrocytes in alginate bead culture under low (5%) and (21%) high oxygen supply. Isolated bovine articular chondrocytes were dedifferentiated and multiplied by 2-week monolayer culture under 21% oxygen. They were subcultured at a density of 10(7) cells/mL in six different commercially available sodium alginates (1.2%, w/v) and held under 21 or 5% oxygen for 3 weeks. Proliferation (DNA measurement on days 0 and 21 of culture), collagen type II production (immunocytochemistry and Western blotting), and [(3)H]proline and [(35)S]sulfate incorporation were monitored. Collagen type II production was significantly stronger under 5% oxygen compared with 21% oxygen in two alginates (three other alginates nearly reached the significance level). However, alginate-based differences proved not to be significant. [(3)H]Proline incorporation was not influenced by alginate but showed strong oxygen dependency (up to 3-fold higher under 5% oxygen). For [(35)S]sulfate incorporation oxygen dependency was even stronger (up to 8-fold higher under 5% oxygen) and significant alginate-dependent differences were found for several alginates. The effects of the different alginates did not correlate with their pH, viscosity, or guluronic:mannuronic acid ratio. Thus, the type of alginate and even more, the oxygen supply, influence the redifferentiation and matrix production of dedifferentiated bovine articular chondrocytes. PMID:15684688

  19. Scaffolding Student Participation in Mathematical Practices

    ERIC Educational Resources Information Center

    Moschkovich, Judit N.

    2015-01-01

    The concept of scaffolding can be used to describe various types of adult guidance, in multiple settings, across different time scales. This article clarifies what we mean by scaffolding, considering several questions specifically for scaffolding in mathematics: What theoretical assumptions are framing scaffolding? What is being scaffolded? At…

  20. 49 CFR 214.109 - Scaffolding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... requirements: (1) Each scaffold and scaffold component, except suspension ropes and guardrail systems, but... least four times the maximum intended load applied or transmitted to that scaffold or scaffold component... guardrail system and the walking/working level. (b) Scaffolds shall not be altered or moved while they...

  1. 49 CFR 214.109 - Scaffolding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... requirements: (1) Each scaffold and scaffold component, except suspension ropes and guardrail systems, but... least four times the maximum intended load applied or transmitted to that scaffold or scaffold component... guardrail system and the walking/working level. (b) Scaffolds shall not be altered or moved while they...

  2. 49 CFR 214.109 - Scaffolding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... requirements: (1) Each scaffold and scaffold component, except suspension ropes and guardrail systems, but... least four times the maximum intended load applied or transmitted to that scaffold or scaffold component... guardrail system and the walking/working level. (b) Scaffolds shall not be altered or moved while they...

  3. 49 CFR 214.109 - Scaffolding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... requirements: (1) Each scaffold and scaffold component, except suspension ropes and guardrail systems, but... least four times the maximum intended load applied or transmitted to that scaffold or scaffold component... guardrail system and the walking/working level. (b) Scaffolds shall not be altered or moved while they...

  4. 49 CFR 214.109 - Scaffolding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... requirements: (1) Each scaffold and scaffold component, except suspension ropes and guardrail systems, but... least four times the maximum intended load applied or transmitted to that scaffold or scaffold component... guardrail system and the walking/working level. (b) Scaffolds shall not be altered or moved while they...

  5. Bioactive apatite incorporated alginate microspheres with sustained drug-delivery for bone regeneration application.

    PubMed

    Li, Haibin; Jiang, Fei; Ye, Song; Wu, Yingying; Zhu, Kaiping; Wang, Deping

    2016-05-01

    The strontium-substituted hydroxyapatite microspheres (SrHA) incorporated alginate composite microspheres (SrHA/Alginate) were prepared via adding SrHA/alginate suspension dropwise into calcium chloride solution, in which the gel beads were formed by means of crosslinking reaction. The structure, morphology and in vitro bioactivity of the composite microspheres were studied by using XRD, SEM and EDS methods. The biological behaviors were characterized and analyzed through inductively coupled plasma optical emission spectroscopy (ICP-OES), CCK-8, confocal laser microscope and ALP activity evaluations. The experimental results indicated that the synthetic SrHA/Alginate showed similar morphology to the well-known alginate microspheres (Alginate) and both of them possessed a great in vitro bioactivity. Compared with the control Alginate, the SrHA/Alginate enhanced MC3T3-E1 cell proliferation and ALP activity by releasing osteoinductive and osteogenic Sr ions. Furthermore, vancomycin was used as a model drug to investigate the drug release behaviors of the SrHA/Alginate, Alginate and SrHA. The results suggested that the SrHA/Alginate had a highest drug-loading efficiency and best controlled drug release properties. Additionally, the SrHA/Alginate was demonstrated to be pH-sensitive as well. The increase of the pH value in phosphate buffer solution (PBS) accelerated the vancomycin release. Accordingly, the multifunctional SrHA/Alginate can be applied in the field of bioactive drug carriers and bone filling materials. PMID:26952484

  6. Design, construction and mechanical testing of digital 3D anatomical data-based PCL-HA bone tissue engineering scaffold.

    PubMed

    Yao, Qingqiang; Wei, Bo; Guo, Yang; Jin, Chengzhe; Du, Xiaotao; Yan, Chao; Yan, Junwei; Hu, Wenhao; Xu, Yan; Zhou, Zhi; Wang, Yijin; Wang, Liming

    2015-01-01

    The study aims to investigate the techniques of design and construction of CT 3D reconstructional data-based polycaprolactone (PCL)-hydroxyapatite (HA) scaffold. Femoral and lumbar spinal specimens of eight male New Zealand white rabbits were performed CT and laser scanning data-based 3D printing scaffold processing using PCL-HA powder. Each group was performed eight scaffolds. The CAD-based 3D printed porous cylindrical stents were 16 piece × 3 groups, including the orthogonal scaffold, the Pozi-hole scaffold and the triangular hole scaffold. The gross forms, fiber scaffold diameters and porosities of the scaffolds were measured, and the mechanical testing was performed towards eight pieces of the three kinds of cylindrical scaffolds, respectively. The loading force, deformation, maximum-affordable pressure and deformation value were recorded. The pore-connection rate of each scaffold was 100 % within each group, there was no significant difference in the gross parameters and micro-structural parameters of each scaffold when compared with the design values (P > 0.05). There was no significant difference in the loading force, deformation and deformation value under the maximum-affordable pressure of the three different cylinder scaffolds when the load was above 320 N. The combination of CT and CAD reverse technology could accomplish the design and manufacturing of complex bone tissue engineering scaffolds, with no significant difference in the impacts of the microstructures towards the physical properties of different porous scaffolds under large load.

  7. Bioresorbable Scaffolds for Atheroregression: Understanding of Transient Scaffolding.

    PubMed

    Kharlamov, Alexander N

    2016-01-01

    This review focuses on the clinical and biological features of the bioresorbable scaffolds in interventional cardiology highlighting scientific achievements and challenges of the transient scaffolding with Absorb BVS. Special attention is granted to the vascular biology pathways which, involved in the resorption of scaffold, artery remodeling and mechanisms of Glagovian atheroregression setting the stage for subsequent clinical applications. Twenty five years ago Glagov described the phenomenon of limited external elastic membrane enlargement in response to an increase in plaque burden. We believe this threshold becomes the target for development of strategies that reverse atherosclerosis, and particularly transient scaffolding has a potential to be a tool to ultimately conquer atherosclerosis. PMID:26818488

  8. In vitro evaluation of alginate encapsulated adipose-tissue stromal cells for use as injectable bone graft substitute

    SciTech Connect

    Abbah, S.A.; Lu, W.W. . E-mail: wwlu@hkusua.hku.hk; Chan, D.; Cheung, K.M.C.; Liu, W.G.; Zhao, F.; Li, Z.Y.; Leong, J.C.Y.; Luk, K.D.K.

    2006-08-18

    This study aims to investigate the survival and osteogenic behavior of murine-derived adipose-tissue stromal cells (ATSCs) encapsulated in alginate microcapsules thereby instigating further studies in this cell delivery strategy for in vivo osteogenesis. Cell viability was quantified using a tetrazolium-based assay and osteogenic differentiation was evaluated by both alkaline-phosphatase (ALP) histochemistry and osteocalcin mRNA analysis. Following microencapsulation, cell numbers increased from 3.9 x 10{sup 3} on day 1 to 7.8 x 10{sup 3} on day 7 and maintained excellent viability in the course of 21-day culture. ALP was 6.9, 5.5, and 3.2 times higher than monolayer cultures on days 7, 14, and 21, respectively. In addition, osteocalcin mRNA was detectable in encapsulated cultures earlier (day 14) than monolayer cultures. We conclude that alginate microcapsules can act as three-dimensional matrix for ATSC proliferation and has potential for use as injectable, biodegradable scaffold in bone tissue engineering.

  9. The effect of autologous bone marrow stromal cells differentiated on scaffolds for canine tibial bone reconstruction.

    PubMed

    Özdal-Kurt, F; Tuğlu, I; Vatansever, H S; Tong, S; Deliloğlu-Gürhan, S I

    2015-01-01

    Bone marrow contains mesenchymal stem cells that form many tissues. Various scaffolds are available for bone reconstruction by tissue engineering. Osteoblastic differentiated bone marrow stromal cells (BMSC) promote osteogenesis on scaffolds and stimulate bone regeneration. We investigated the use of cultured autologous BMSC on different scaffolds for healing defects in tibias of adult male canines. BMSC were isolated from canine humerus bone marrow, differentiated into osteoblasts in culture and loaded onto porous ceramic scaffolds including hydroxyapatite 1, hydroxyapatite gel and calcium phosphate. Osteoblast differentiation was verified by osteonectine and osteocalcine immunocytochemistry. The scaffolds with stromal cells were implanted in the tibial defect. Scaffolds without stromal cells were used as controls. Sections from the defects were processed for histological, ultrastructural, immunohistochemical and histomorphometric analyses to analyze the healing of the defects. BMSC were spread, allowed to proliferate and differentiate to osteoblasts as shown by alizarin red histochemistry, and osteocalcine and osteonectine immunostaining. Scanning electron microscopy showed that BMSC on the scaffolds were more active and adhesive to the calcium phosphate scaffold compared to the others. Macroscopic bone formation was observed in all groups, but scaffolds with stromal cells produced significantly better results. Bone healing occurred earlier and faster with stromal cells on the calcium phosphate scaffold and produced more callus compared to other scaffolds. Tissue healing and osteoblastic marker expression also were better with stromal cells on the scaffolds. Increased trabecula formation, cell density and decreased fibrosis were observed in the calcium phosphate scaffold with stromal cells. Autologous cultured stromal cells on the scaffolds were useful for healing of canine tibial bone defects. The calcium phosphate scaffold was the best for both cell

  10. Aging and microwave effects on alginate/chitosan matrices.

    PubMed

    Wong, Tin Wui; Chan, Lai Wah; Kho, Shyan Bin; Heng, Paul Wan Sia

    2005-06-01

    The influence of microwave irradiation on the drug release properties of freshly prepared and aged alginate, alginate-chitosan and chitosan beads was investigated. The beads were prepared by extrusion method with sulphathiazole as a model drug. The dried beads were subjected to microwave irradiation at 80 W for 10 min, 20 min or three consecutive cycles of 10 and 20 min, respectively. The profiles of drug dissolution, drug content, drug stability, drug polymorphism, drug-polymer interaction, polymer crosslinkage and complexation were determined by dissolution testing, drug content assay, differential scanning calorimetry and Fourier transform infra-red spectroscopy. The chemical stability of drug embedded in beads was unaffected by microwave conditions and length of storage time. The release property of drug was mainly governed by the extent of polymer interaction in beads. The aged alginate beads required intermittent cycles of microwave irradiation to induce drug release retarding effect in contrast to their freshly prepared samples. Unlike the alginate beads, the level of polymer interaction was higher in aged alginate-chitosan beads than the corresponding fresh beads. The drug release retarding property of aged alginate-chitosan beads could be significantly enhanced through subjecting the beads to microwave irradiation for 10 min. No further change in drug release from these beads was observed beyond 30 min of microwave irradiation. Unlike beads containing alginate, the rate and extent of drug released from the aged chitosan beads were higher upon treatment by microwave in spite of the higher degree of polymer interaction shown by the latter on prolonged storage. The observation suggested that the response of polymer matrix to microwave irradiation in induction of drug release retarding property was largely affected by the molecular arrangement of the polymer chains.

  11. Extraction and physicochemical characterization of Sargassum vulgare alginate from Brazil.

    PubMed

    Torres, Marcia R; Sousa, Alessandra P A; Silva Filho, Eduardo A T; Melo, Dirce F; Feitosa, Judith P A; de Paula, Regina C M; Lima, Maria G S

    2007-10-15

    Alginate fractions from Sargassum vulgare brown seaweed were characterized by (1)H NMR and fluorescence spectroscopy and by rheological measurements. The alginate extraction conditions were investigated. In order to carry out the structural and physicochemical characterization, samples extracted for 1 and 5h at 60 degrees C were further purified by re-precipitation with ethanol and denoted as SVLV (S. vulgare low viscosity) and SVHV (S. vulgare high viscosity), respectively. The M/G ratio values for SVLV and SVHV were 1.56 and 1.27, respectively, higher than the ratio for most Sargassum spp. alginates (0.19-0.82). The homopolymeric blocks F(GG) and F(MM) of these fractions characterized by (1)H NMR spectroscopy were 0.43 and 0.55 for SVHV and 0.36 and 0.58 for SVLV samples, respectively, these values typically being within 0.28-0.77 and 0.07-0.41, respectively. Therefore, the alginate samples from S. vulgare are much richer in mannuronic block structures than those from other Sargassum species. Values of M(w) for alginate samples were also calculated using intrinsic viscosity data. The M(w) value for SVLV (1.94 x 10(5)g/mol) was lower than that for SVHV (3.3 x 10(5)g/mol). Newtonian behavior was observed for a solution concentration as high as 0.7% for SVLV, while for SVHV the solutions behaved as a Newtonian fluid up to 0.5%. The optimal conditions for obtaining the alginates from S. vulgare were 60 degrees C and 5h extraction. Under these conditions, a more viscous alginate in higher yield was extracted from the seaweed biomass. PMID:17585891

  12. Enzymatic mineralization of silk scaffolds.

    PubMed

    Samal, Sangram K; Dash, Mamoni; Declercq, Heidi A; Gheysens, Tom; Dendooven, Jolien; Van Der Voort, Pascal; Cornelissen, Ria; Dubruel, Peter; Kaplan, David L

    2014-07-01

    The present study focuses on the alkaline phosphatase (ALP) mediated formation of apatitic minerals on porous silk fibroin protein (SFP) scaffolds. Porous SFP scaffolds impregnated with different concentrations of ALP are homogeneously mineralized under physiological conditions. The mineral structure is apatite while the structures differ as a function of the ALP concentration. Cellular adhesion, proliferation, and colonization of osteogenic MC3T3 cells improve on the mineralized SFP scaffolds. These findings suggest a simple process to generate mineralized scaffolds that can be used to enhanced bone tissue engineering-related utility. PMID:24610728

  13. Immobilization of a Plant Lipase from Pachira aquatica in Alginate and Alginate/PVA Beads.

    PubMed

    Bonine, Bárbara M; Polizelli, Patricia Peres; Bonilla-Rodriguez, Gustavo O

    2014-01-01

    This study reports the immobilization of a new lipase isolated from oleaginous seeds of Pachira aquatica, using beads of calcium alginate (Alg) and poly(vinyl alcohol) (PVA). We evaluated the morphology, number of cycles of reuse, optimum temperature, and temperature stability of both immobilization methods compared to the free enzyme. The immobilized enzymes were more stable than the free enzyme, keeping 60% of the original activity after 4 h at 50°C. The immobilized lipase was reused several times, with activity decreasing to approximately 50% after 5 cycles. Both the free and immobilized enzymes were found to be optimally active between 30 and 40°C.

  14. Mechanical Improvements to Reinforced Porous Silk Scaffolds

    PubMed Central

    Gil, Eun Seok; Kluge, Jonathan A.; Rockwood, Danielle N.; Rajkhowa, Rangam; Wang, Lijing; Wang, Xungai; Kaplan, David L

    2012-01-01

    Load bearing porous biodegradable scaffolds are required to engineer functional tissues such as bone. Mechanical improvements to porogen leached scaffolds prepared from silk proteins were systematically studied through the addition of silk particles in combination with silk solution concentration, exploiting interfacial compatibility between the two components. Solvent solutions of silk up to 32 w/v% were successfully prepared in hexafluoroisopropanaol (HFIP) for the study. The mechanical properties of the reinforced silk scaffolds correlated to the material density and matched by a power law relationship, independent of the ratio of silk particles to matrix. These results were similar to the relationships previously shown for cancellous bone. The mechanism behind the increased mechanical properties was a densification effect, and not the effect of including stiffer silk particles into the softer silk continuous matrix. A continuous interface between the silk matrix and the silk particles, as well as homogeneous distribution of the silk particles within the matrix were observed. Furthermore, we note that the roughness of the pore walls was controllable by varying the ratio of particles matrix, providing a route to control topography. The rate of proteolytic hydrolysis of the scaffolds decreased with increase in mass of silk used in the matrix and with increasing silk particle content. PMID:21793193

  15. Acellular organ scaffolds for tumor tissue engineering

    NASA Astrophysics Data System (ADS)

    Guller, Anna; Trusova, Inna; Petersen, Elena; Shekhter, Anatoly; Kurkov, Alexander; Qian, Yi; Zvyagin, Andrei

    2015-12-01

    Rationale: Tissue engineering (TE) is an emerging alternative approach to create models of human malignant tumors for experimental oncology, personalized medicine and drug discovery studies. Being the bottom-up strategy, TE provides an opportunity to control and explore the role of every component of the model system, including cellular populations, supportive scaffolds and signalling molecules. Objectives: As an initial step to create a new ex vivo TE model of cancer, we optimized protocols to obtain organ-specific acellular matrices and evaluated their potential as TE scaffolds for culture of normal and tumor cells. Methods and results: Effective decellularization of animals' kidneys, ureter, lungs, heart, and liver has been achieved by detergent-based processing. The obtained scaffolds demonstrated biocompatibility and growthsupporting potential in combination with normal (Vero, MDCK) and tumor cell lines (C26, B16). Acellular scaffolds and TE constructs have been characterized and compared with morphological methods. Conclusions: The proposed methodology allows creation of sustainable 3D tumor TE constructs to explore the role of organ-specific cell-matrix interaction in tumorigenesis.

  16. Engineered Biopolymeric Scaffolds for Chronic Wound Healing.

    PubMed

    Dickinson, Laura E; Gerecht, Sharon

    2016-01-01

    Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components, and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered. PMID:27547189

  17. Engineered Biopolymeric Scaffolds for Chronic Wound Healing

    PubMed Central

    Dickinson, Laura E.; Gerecht, Sharon

    2016-01-01

    Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components, and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered. PMID:27547189

  18. Fabrication of functional PLGA-based electrospun scaffolds and their applications in biomedical engineering.

    PubMed

    Zhao, Wen; Li, Jiaojiao; Jin, Kaixiang; Liu, Wenlong; Qiu, Xuefeng; Li, Chenrui

    2016-02-01

    Electrospun PLGA-based scaffolds have been applied extensively in biomedical engineering, such as tissue engineering and drug delivery system. Due to lack of the recognition sites on cells, hydropholicity and single-function, the applications of PLGA fibrous scaffolds are limited. In order to tackle these issues, many works have been done to obtain functional PLGA-based scaffolds, including surface modifications, the fabrication of PLGA-based composite scaffolds and drug-loaded scaffolds. The functional PLGA-based scaffolds have significantly improved cell adhesion, attachment and proliferation. Moreover, the current study has summarized the applications of functional PLGA-based scaffolds in wound dressing, vascular and bone tissue engineering area as well as drug delivery system.

  19. Fabrication of functional PLGA-based electrospun scaffolds and their applications in biomedical engineering.

    PubMed

    Zhao, Wen; Li, Jiaojiao; Jin, Kaixiang; Liu, Wenlong; Qiu, Xuefeng; Li, Chenrui

    2016-02-01

    Electrospun PLGA-based scaffolds have been applied extensively in biomedical engineering, such as tissue engineering and drug delivery system. Due to lack of the recognition sites on cells, hydropholicity and single-function, the applications of PLGA fibrous scaffolds are limited. In order to tackle these issues, many works have been done to obtain functional PLGA-based scaffolds, including surface modifications, the fabrication of PLGA-based composite scaffolds and drug-loaded scaffolds. The functional PLGA-based scaffolds have significantly improved cell adhesion, attachment and proliferation. Moreover, the current study has summarized the applications of functional PLGA-based scaffolds in wound dressing, vascular and bone tissue engineering area as well as drug delivery system. PMID:26652474

  20. Novel nanocomposite biomaterials with controlled copper/calcium release capability for bone tissue engineering multifunctional scaffolds

    PubMed Central

    Cattalini, J. P.; Hoppe, A.; Pishbin, F.; Roether, J.; Boccaccini, A. R.; Lucangioli, S.; Mouriño, V.

    2015-01-01

    This work aimed to develop novel composite biomaterials for bone tissue engineering (BTE) made of bioactive glass nanoparticles (Nbg) and alginate cross-linked with Cu2+ or Ca2+ (AlgNbgCu, AlgNbgCa, respectively). Two-dimensional scaffolds were prepared and the nanocomposite biomaterials were characterized in terms of morphology, mechanical strength, bioactivity, biodegradability, swelling capacity, release profile of the cross-linking cations and angiogenic properties. It was found that both Cu2+ and Ca2+ are released in a controlled and sustained manner with no burst release observed. Finally, in vitro results indicated that the bioactive ions released from both nanocomposite biomaterials were able to stimulate the differentiation of rat bone marrow-derived mesenchymal stem cells towards the osteogenic lineage. In addition, the typical endothelial cell property of forming tubes in Matrigel was observed for human umbilical vein endothelial cells when in contact with the novel biomaterials, particularly AlgNbgCu, which indicates their angiogenic properties. Hence, novel nanocomposite biomaterials made of Nbg and alginate cross-linked with Cu2+ or Ca2+ were developed with potential applications for preparation of multifunctional scaffolds for BTE. PMID:26269233

  1. Formulation of an alginate-vineyard pruning waste composite as a new eco-friendly adsorbent to remove micronutrients from agroindustrial effluents.

    PubMed

    Vecino, X; Devesa-Rey, R; Moldes, A B; Cruz, J M

    2014-09-01

    The cellulosic fraction of vineyard pruning waste (free of hemicellulosic sugars) was entrapped in calcium alginate beads and evaluated as an eco-friendly adsorbent for the removal of different nutrients and micronutrients (Mg, P, Zn, K, N-NH4, SO4, TN, TC and PO4) from an agroindustrial effluent (winery wastewater). Batch adsorption studies were performed by varying the amounts of cellulosic adsorbent (0.5-2%), sodium alginate (1-5%) and calcium chloride (0.05-0.9M) included in the biocomposite. The optimal formulation of the adsorbent composite varied depending on the target contaminant. Thus, for the adsorption of cationic contaminants (Mg, Zn, K, N-NH4 and TN), the best mixture comprised 5% sodium alginate, 0.05M calcium chloride and 0.5% cellulosic vineyard pruning waste, whereas for removal of anionic compounds (P, SO4 and PO4), the optimal mixture comprised 1% sodium alginate, 0.9M calcium chloride and 0.5% cellulosic vineyard pruning waste. To remove TC from the winery wastewater, the optimal mixture comprised 3% of sodium alginate, 0.475M calcium chloride and 0.5% cellulosic vineyard pruning waste.

  2. Instruction, Cognitive Scaffolding, and Motivational Scaffolding in Writing Center Tutoring

    ERIC Educational Resources Information Center

    Mackiewicz, Jo; Thompson, Isabelle

    2014-01-01

    In this study, we quantitatively analyze the discourse of experienced writing center tutors in 10 highly satisfactory conferences. Specifically, we analyze tutors' instruction, cognitive scaffolding, and motivational scaffolding, all tutoring strategies identified in prior research from other disciplines as educationally effective. We find…

  3. PEP_scaffolder: using (homologous) proteins to scaffold genomes

    PubMed Central

    Zhu, Bai-Han; Song, Ying-Nan; Xue, Wei; Xu, Gui-Cai; Xiao, Jun; Sun, Ming-Yuan; Sun, Xiao-Wen; Li, Jiong-Tang

    2016-01-01

    Motivation: Recovering the gene structures is one of the important goals of genome assembly. In low-quality assemblies, and even some high-quality assemblies, certain gene regions are still incomplete; thus, novel scaffolding approaches are required to complete gene regions. Results: We developed an efficient and fast genome scaffolding method called PEP_scaffolder, using proteins to scaffold genomes. The pipeline aims to recover protein-coding gene structures. We tested the method on human contigs; using human UniProt proteins as guides, the improvement on N50 size was 17% increase with an accuracy of ∼97%. PEP_scaffolder improved the proportion of fully covered proteins among all proteins, which was close to the proportion in the finished genome. The method provided a high accuracy of 91% using orthologs of distant species. Tested on simulated fly contigs, PEP_scaffolder outperformed other scaffolders, with the shortest running time and the highest accuracy. Availability and Implementation: The software is freely available at http://www.fishbrowser.org/software/PEP_scaffolder/ Contact: lijt@cafs.ac.cn Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27334475

  4. Development of a porcine renal extracellular matrix scaffold as a platform for kidney regeneration.

    PubMed

    Choi, Seock Hwan; Chun, So Young; Chae, Seon Yeong; Kim, Jin Rae; Oh, Se Heang; Chung, Sung Kwang; Lee, Jin Ho; Song, Phil Hyun; Choi, Gyu-Seog; Kim, Tae-Hwan; Kwon, Tae Gyun

    2015-04-01

    Acellular scaffolds, possessing an intact three-dimensional extracellular matrix (ECM) architecture and biochemical components, are promising for regeneration of complex organs, such as the kidney. We have successfully developed a porcine renal acellular scaffold and analyzed its physical/biochemical characteristics, biocompatibility, and kidney reconstructive potential. Segmented porcine kidney cortexes were treated with either 1% (v/v) Triton X-100 (Triton) or sodium dodecyl sulfate (SDS). Scanning electron microscopy showed both treatments preserved native tissue architecture, including porosity and composition. Swelling behavior was higher in the Triton-treated compared with the SDS-treated scaffold. Maximum compressive strength was lower in the Triton-treated compared with the SDS-treated scaffold. Attenuated total reflective-infrared spectroscopy showed the presence of amide II (-NH) in both scaffolds. Furthermore, richer ECM protein and growth factor contents were observed in the Triton-treated compared with SDS-treated scaffold. Primary human kidney cell adherence, viability, and proliferation were enhanced on the Triton-treated scaffold compared with SDS-treated scaffold. Following murine in vivo implantation, tumorigenecity was absent for both scaffolds after 8 weeks and in the Triton-treated scaffold only, glomeruli-like structure formation and neovascularity were observed. We identified 1% Triton X-100 as a more suitable decellularizing agent for porcine renal ECM scaffolds prior to kidney regeneration.

  5. A Hydrogel-Mineral Composite Scaffold for Osteochondral Interface Tissue Engineering

    PubMed Central

    Khanarian, Nora T.; Jiang, Jie; Wan, Leo Q.; Mow, Van C.

    2012-01-01

    Osteoarthritis is the leading cause of physical disability among Americans, and tissue engineered cartilage grafts have emerged as a promising treatment option for this debilitating condition. Currently, the formation of a stable interface between the cartilage graft and subchondral bone remains a significant challenge. This study evaluates the potential of a hybrid scaffold of hydroxyapatite (HA) and alginate hydrogel for the regeneration of the osteochondral interface. Specifically, the effects of HA on the response of chondrocytes were determined, focusing on changes in matrix production and mineralization, as well as scaffold mechanical properties over time. Additionally, the optimal chondrocyte population for interface tissue engineering was evaluated. It was observed that the HA phase of the composite scaffold promoted the formation of a proteoglycan- and type II collagen–rich matrix when seeded with deep zone chondrocytes. More importantly, the elevated biosynthesis translated into significant increases in both compressive and shear moduli relative to the mineral-free control. Presence of HA also promoted chondrocyte hypertrophy and type X collagen deposition. These results demonstrate that the hydrogel–calcium phosphate composite supported the formation of a calcified cartilage-like matrix and is a promising scaffold design for osteochondral interface tissue engineering. PMID:21919797

  6. Chondrocyte Culture in Three Dimensional Alginate Sulfate Hydrogels Promotes Proliferation While Maintaining Expression of Chondrogenic Markers

    PubMed Central

    Mhanna, Rami; Kashyap, Aditya; Palazzolo, Gemma; Vallmajo-Martin, Queralt; Becher, Jana; Möller, Stephanie; Schnabelrauch, Matthias

    2014-01-01

    The loss of expression of chondrogenic markers during monolayer expansion remains a stumbling block for cell-based treatment of cartilage lesions. Here, we introduce sulfated alginate hydrogels as a cartilage biomimetic biomaterial that induces cell proliferation while maintaining the chondrogenic phenotype of encapsulated chondrocytes. Hydroxyl groups of alginate were converted to sulfates by incubation with sulfur trioxide–pyridine complex (SO3/pyridine), yielding a sulfated material cross-linkable with calcium chloride. Passage 3 bovine chondrocytes were encapsulated in alginate and alginate sulfate hydrogels for up to 35 days. Cell proliferation was five-fold higher in alginate sulfate compared with alginate (p=0.038). Blocking beta1 integrins in chondrocytes within alginate sulfate hydrogels significantly inhibited proliferation (p=0.002). Sulfated alginate increased the RhoA activity of chondrocytes compared with unmodified alginate, an increase that was blocked by β1 blocking antibodies (p=0.017). Expression and synthesis of type II collagen, type I collagen, and proteoglycan was not significantly affected by the encapsulation material evidenced by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry. Alginate sulfate constructs showed an opaque appearance in culture, whereas the unmodified alginate samples remained translucent. In conclusion, alginate sulfate provides a three dimensional microenvironment that promotes both chondrocyte proliferation and maintenance of the chondrogenic phenotype and represents an important advance for chondrocyte-based cartilage repair therapies providing a material in which cell expansion can be done in situ. PMID:24320935

  7. Electrodeposition of alginate gels for construction of vascular-like structures.

    PubMed

    Ozawa, Fumisato; Ino, Kosuke; Takahashi, Yasufumi; Shiku, Hitoshi; Matsue, Tomokazu

    2013-04-01

    In this study, tubular hydrogel structures were constructed via electrodeposition using alginate gels. Electrolysis of water in alginate solutions with calcium carbonate particles induced gel aggregation around Pt wire electrodes, forming tubular alginate gel structures. The simple method is a promising approach for construction of multi-layer tubular hydrogel structures for tissue engineering.

  8. Cloning of alginate lyase gene (alxM) and expression in Escherichia coli.

    PubMed Central

    Brown, B J; Preston, J F; Ingram, L O

    1991-01-01

    The alxM gene encoding a D-mannuronan-specific alginate lyase has been cloned from a marine bacterium isolated as an epiphyte on the brown alga, Sargassum fluitans. Expression of this gene in Escherichia coli provides a source of this enzyme for probing alginate structure and modifying the mannuronan-rich alginate polymers produced by bacterial pathogens. Images PMID:1872617

  9. Novel Antibacterial Nanofibrous PLLA Scaffolds

    PubMed Central

    Feng, Kai; Sun, Hongli; Bradley, Mark A.; Dupler, Ellen J.; Giannobile, William V.; Ma, Peter X.

    2010-01-01

    In order to achieve high local bioactivity and low systemic side effects of antibiotics in the treatment of dental, periodontal and bone infections, a localized and temporally controlled delivery system is crucial. In this study, a three-dimensional (3D) porous tissue engineering scaffold was developed with the ability to release antibiotics in a controlled fashion for long-term inhibition of bacterial growth. The highly soluble antibiotic drug, Doxycycline (DOXY), was successfully incorporated into PLGA nanospheres using a modified water-in-oil-in-oil (w/o/o) emulsion method. The PLGA nanospheres (NS) were then incorporated into prefabricated nanofibrous PLLA scaffolds with a well interconnected macroporous structure. The release kinetics of DOXY from four different PLGA NS formulations on a PLLA scaffold was investigated. DOXY could be released from the NS-scaffolds in a locally and temporally controlled manner. The DOXY release is controlled by DOXY diffusion out of the NS and is strongly dependent upon the physical and chemical properties of the PLGA. While PLGA50-6.5K, PLGA50-64K, and PLGA75-113K NS-scaffolds discharge DOXY rapidly with a high initial burst release, PLGA85-142K NS-scaffold can extend the release of DOXY to longer than 6 weeks with a low initial burst release. Compared to NS alone, the NS incorporated on a 3-D scaffold had significantly reduced the initial burst release. In vitro antibacterial tests of PLGA85 NS-scaffold demonstrated its ability to inhibit common bacterial growth (S.aureus and E.coli) for a prolonged duration. The successful incorporation of DOXY onto 3-D scaffolds and its controlled release from scaffolds extends the usage of nano-fibrous scaffolds from the delivery of large molecules such as growth factors to the delivery of small hydrophilic drugs, allowing for a broader application and a more complex tissue engineering strategy. PMID:20570700

  10. Zinc cross-linked hydroxamated alginates for pulsed drug release

    PubMed Central

    Raut, Neha S; Deshmukh, Prasad R; Umekar, Milind J; Kotagale, Nandkishor R

    2013-01-01

    Introduction: Alginates can be tailored chemically to improve solubility, physicochemical, and biological properties and its complexation with metal ion is useful for controlling the drug release. Materials And Methods: Synthesized N,O-dimethyl, N-methyl, or N-Benzyl hydroxylamine derivatives of sodium alginate were subsequently complexed with zinc to form beads. Hydroxamation of sodium alginate was confirmed by Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC). Results: The synthesized polymeric material exhibited reduced aqueous, HCl and NaOH solubility. The hydroxamated derivatives demonstrated pulsed release where change in pH of the dissolution medium stimulated the atenolol release. Conclusion: Atenolol loaded Zn cross-linked polymeric beads demonstrated the sustained the plasma drug levels with increased half-life. Although the synthesized derivatives greatly altered the aqueous solubility of sodium alginate, no significant differences in in vitro and in vivo atenolol release behavior amongst the N,O-dimethyl, N-methyl, or N-Benzyl hydroxylamine derivatives of sodium alginate were observed. PMID:24350039

  11. Oxidized alginate hydrogels as niche environments for corneal epithelial cells

    PubMed Central

    Wright, Bernice; De Bank, Paul A; Luetchford, Kim A; Acosta, Fernando R; Connon, Che J

    2014-01-01

    Chemical and biochemical modification of hydrogels is one strategy to create physiological constructs that maintain cell function. The aim of this study was to apply oxidised alginate hydrogels as a basis for development of a biomimetic niche for limbal epithelial stem cells that may be applied to treating corneal dysfunction. The stem phenotype of bovine limbal epithelial cells (LEC) and the viability of corneal epithelial cells (CEC) were examined in oxidised alginate gels containing collagen IV over a 3-day culture period. Oxidation increased cell viability (P ≤ 0.05) and this improved further with addition of collagen IV (P ≤ 0.01). Oxidised gels presented larger internal pores (diameter: 0.2–0.8 µm) than unmodified gels (pore diameter: 0.05–0.1 µm) and were significantly less stiff (P ≤ 0.001), indicating that an increase in pore size and a decrease in stiffness contributed to improved cell viability. The diffusion of collagen IV from oxidised alginate gels was similar to that of unmodified gels suggesting that oxidation may not affect the retention of extracellular matrix proteins in alginate gels. These data demonstrate that oxidised alginate gels containing corneal extracellular matrix proteins can influence corneal epithelial cell function in a manner that may impact beneficially on corneal wound healing therapy. © 2013 The Authors. Journal of Biomedical Materials Research Part A Published byWiley Periodicals, Inc. Part A: 102A: 3393–3400, 2014. PMID:24142706

  12. Alginate Nanoparticles as a Promising Adjuvant and Vaccine Delivery System

    PubMed Central

    Sarei, F.; Dounighi, N. Mohammadpour; Zolfagharian, H.; Khaki, P.; Bidhendi, S. Moradi

    2013-01-01

    During last decades, diphtheria has remained as a serious disease that still outbreaks and can occur worldwide. Recently, new vaccine delivery systems have been developed by using the biodegradable and biocompatible polymers such as alginate. Alginate nanoparticles as a carrier with adjuvant and prolong release properties that enhance the immunogenicity of vaccines. In this study diphtheria toxoid loaded nanoparticles were prepared by ionic gelation technique and characterized with respect to size, zeta potential, morphology, encapsulation efficiency, release profile, and immunogenicity. Appropriate parameters (calcium chloride and sodium alginate concentration, homogenization rate and homogenization time) redounded to the formation of suitable nanoparticles with a mean diameter of 70±0.5 nm. The loading studies of the nanoparticles resulted in high loading capacities (>90%) and subsequent release studies showed prolong profile. The stability and antigenicity of toxoid were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and ouchterlony test and proved that the encapsulation process did not affect the antigenic integrity and activity. Guinea pigs immunized with the diphtheria toxoid-loaded alginate nanoparticles showed highest humoral immune response than conventional vaccine. It is concluded that, with regard to the desirable properties of nanoparticles and high immunogenicity, alginate nanoparticles could be considered as a new promising vaccine delivery and adjuvant system. PMID:24302799

  13. Preparation of alginate beads containing a prodrug of diethylenetriaminepentaacetic acid

    PubMed Central

    Yang, Yu-Tsai; Di Pasqua, Anthony J.; He, Weiling; Tsai, Tsuimin; Sueda, Katsuhiko; Zhang, Yong; Jay, Michael

    2012-01-01

    A penta-ethyl ester prodrug of the radionuclide decorporation agent diethylenetriaminepentaacetic acid (DTPA), which exists as an oily liquid, was encapsulated in alginate beads by the ionotropic gelation method. An optimal formulation was found by varying initial concentrations of DTPA pentaethyl ester, alginate polymer, Tween 80 surfactant and calcium chloride. All prepared alginate beads were ~1.6 mm in diameter, and the optimal formulation had loading and encapsulation efficiencies of 91.0 ± 1.1 and 72.6 ± 2.2%, respectively, and only 3.2 ± 0.8% water absorption after storage at room temperature in ~80% relative humidity. Moreover, Fourier transform infrared spectroscopy showed that DTPA penta-ethyl ester did not react with excipients during formation of the DTPA penta-ethyl ester-containing alginate beads. Release of prodrug from alginate beads was via anomalous transport, and its stability enhanced by encapsulation. Collectively, these data suggest that this solid dosage form may be suitable for oral administration after radionuclide contamination. PMID:23399237

  14. Encapsulation optimization of lemon balm antioxidants in calcium alginate hydrogels.

    PubMed

    Najafi-Soulari, Samira; Shekarchizadeh, Hajar; Kadivar, Mahdi

    2016-11-01

    Calcium alginate hydrogel beads were used to encapsulate lemon balm extract. Chitosan layer was used to investigate the effect of hydrogel coating. To determine the interactions of antioxidant compounds of extract with encapsulation materials and its stability, microstructure of hydrogel beads was thoroughly monitored using scanning electron microscopy and Fourier transform infrared (FTIR). Total polyphenols content and antiradical activity of lemon balm extract were also evaluated before and after encapsulation. Three significant parameters (lemon balm extract, sodium alginate, and calcium chloride concentrations) were optimized by response surface methodology to obtain maximum encapsulation efficiency. The FTIR spectra showed no interactions between extract and polymers as there were no new band in spectra of alginate hydrogel after encapsulation of active compounds of lemon balm extract. The antioxidant activity of lemon balm extract did not change after encapsulation. Therefore, it was found that alginate is a suitable material for encapsulation of natural antioxidants. Sodium alginate solution concentration, 1.84%, lemon balm extract concentration, 0.4%, and calcium chloride concentration, 0.2% was determined to be the optimum condition to reach maximum encapsulation efficiency.

  15. Oxidized alginate hydrogels as niche environments for corneal epithelial cells.

    PubMed

    Wright, Bernice; De Bank, Paul A; Luetchford, Kim A; Acosta, Fernando R; Connon, Che J

    2014-10-01

    Chemical and biochemical modification of hydrogels is one strategy to create physiological constructs that maintain cell function. The aim of this study was to apply oxidised alginate hydrogels as a basis for development of a biomimetic niche for limbal epithelial stem cells that may be applied to treating corneal dysfunction. The stem phenotype of bovine limbal epithelial cells (LEC) and the viability of corneal epithelial cells (CEC) were examined in oxidised alginate gels containing collagen IV over a 3-day culture period. Oxidation increased cell viability (P ≤ 0.05) and this improved further with addition of collagen IV (P ≤ 0.01). Oxidised gels presented larger internal pores (diameter: 0.2-0.8 µm) than unmodified gels (pore diameter: 0.05-0.1 µm) and were significantly less stiff (P ≤ 0.001), indicating that an increase in pore size and a decrease in stiffness contributed to improved cell viability. The diffusion of collagen IV from oxidised alginate gels was similar to that of unmodified gels suggesting that oxidation may not affect the retention of extracellular matrix proteins in alginate gels. These data demonstrate that oxidised alginate gels containing corneal extracellular matrix proteins can influence corneal epithelial cell function in a manner that may impact beneficially on corneal wound healing therapy.

  16. Encapsulation optimization of lemon balm antioxidants in calcium alginate hydrogels.

    PubMed

    Najafi-Soulari, Samira; Shekarchizadeh, Hajar; Kadivar, Mahdi

    2016-11-01

    Calcium alginate hydrogel beads were used to encapsulate lemon balm extract. Chitosan layer was used to investigate the effect of hydrogel coating. To determine the interactions of antioxidant compounds of extract with encapsulation materials and its stability, microstructure of hydrogel beads was thoroughly monitored using scanning electron microscopy and Fourier transform infrared (FTIR). Total polyphenols content and antiradical activity of lemon balm extract were also evaluated before and after encapsulation. Three significant parameters (lemon balm extract, sodium alginate, and calcium chloride concentrations) were optimized by response surface methodology to obtain maximum encapsulation efficiency. The FTIR spectra showed no interactions between extract and polymers as there were no new band in spectra of alginate hydrogel after encapsulation of active compounds of lemon balm extract. The antioxidant activity of lemon balm extract did not change after encapsulation. Therefore, it was found that alginate is a suitable material for encapsulation of natural antioxidants. Sodium alginate solution concentration, 1.84%, lemon balm extract concentration, 0.4%, and calcium chloride concentration, 0.2% was determined to be the optimum condition to reach maximum encapsulation efficiency. PMID:27540886

  17. The Use of Scaffolds in Musculoskeletal Tissue Engineering

    PubMed Central

    Henson, Frances; Getgood, Alan

    2011-01-01

    The use of bioengineering scaffolds remains an integral part of the tissue engineering concept. A significant amount of basic science and clinical research has been focused on the regeneration of musculoskeletal tissues including bone, articular cartilage, meniscus, ligament and tendon. This review aims to provide the reader with a summary of the principals of using material scaffolds in musculoskeletal tissue engineering applications and how these materials may eventually come to be incorporated in clinical practice. PMID:21886690

  18. Enhanced Control of In Vivo Bone Formation with Surface Functionalized Alginate Microbeads Incorporating Heparin and Human Bone Morphogenetic Protein-2

    PubMed Central

    Abbah, Sunny Akogwu; Liu, Jing; Goh, James Cho Hong

    2013-01-01

    In this study, we tested the hypothesis that a surface functionalization delivery platform incorporating heparin onto strontium alginate microbeads surfaces would convert this “naive carriers” into “mini-reservoirs” for localized in vivo delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2) that will induce functional bone regeneration. In vitro evaluation confirmed that (1) heparin incorporation could immobilize and prolong rhBMP-2 release for approximately 3 weeks; (2) a significant decrease (p<0.01) in rhBMP-2 burst release is attainable depending on initial protein load; and (3) rhBMP-2 released from surface functionalized microbeads retained bioactivity and stimulated higher alkaline phosphatase activity in cultured C2C12 cells when compared with daily administration of fresh bolus rhBMP-2. Subsequently, surface functionalized microbeads were used for in vivo delivery of rhBMP-2 at local sites of posterolateral spinal fusion surgery in rats. The microbeads were loaded into the pores of medical-grade polyepsilone caprolactone-tricalcium phosphate scaffolds before implantation. Results revealed robust bone formation and a biomechanically solid fusion after 6 weeks. When compared with a control group consisting of an equivalent amount of rhBMP-2 that was directly adsorbed onto bare-surfaced microbeads with no heparin, a 5.3-fold increase in bone volume fraction and a 2.6-fold increase in bending stiffness (flexion/extension) were observed. When compared with collagen sponge carriers of rhBMP-2, a 1.5-fold and a 1.3-fold increase in bone volume fraction and bending stiffness were observed, respectively. More importantly, 3D micro-computed tomography images enabled the visualization of a well-contained newly formed bone at ipsilateral implant sites with surface functionalized rhBMP-2 delivery. This was absent with collagen sponge carriers where newly formed bone tissue was poorly contained and crossed over the posterior midline to

  19. Enhanced control of in vivo bone formation with surface functionalized alginate microbeads incorporating heparin and human bone morphogenetic protein-2.

    PubMed

    Abbah, Sunny Akogwu; Liu, Jing; Goh, James Cho Hong; Wong, Hee-Kit

    2013-02-01

    In this study, we tested the hypothesis that a surface functionalization delivery platform incorporating heparin onto strontium alginate microbeads surfaces would convert this "naive carriers" into "mini-reservoirs" for localized in vivo delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2) that will induce functional bone regeneration. In vitro evaluation confirmed that (1) heparin incorporation could immobilize and prolong rhBMP-2 release for approximately 3 weeks; (2) a significant decrease (p<0.01) in rhBMP-2 burst release is attainable depending on initial protein load; and (3) rhBMP-2 released from surface functionalized microbeads retained bioactivity and stimulated higher alkaline phosphatase activity in cultured C(2)C(12) cells when compared with daily administration of fresh bolus rhBMP-2. Subsequently, surface functionalized microbeads were used for in vivo delivery of rhBMP-2 at local sites of posterolateral spinal fusion surgery in rats. The microbeads were loaded into the pores of medical-grade polyepsilone caprolactone-tricalcium phosphate scaffolds before implantation. Results revealed robust bone formation and a biomechanically solid fusion after 6 weeks. When compared with a control group consisting of an equivalent amount of rhBMP-2 that was directly adsorbed onto bare-surfaced microbeads with no heparin, a 5.3-fold increase in bone volume fraction and a 2.6-fold increase in bending stiffness (flexion/extension) were observed. When compared with collagen sponge carriers of rhBMP-2, a 1.5-fold and a 1.3-fold increase in bone volume fraction and bending stiffness were observed, respectively. More importantly, 3D micro-computed tomography images enabled the visualization of a well-contained newly formed bone at ipsilateral implant sites with surface functionalized rhBMP-2 delivery. This was absent with collagen sponge carriers where newly formed bone tissue was poorly contained and crossed over the posterior midline to contralateral

  20. In vitro development of preimplantation porcine embryos using alginate hydrogels as a three-dimensional extracellular matrix.

    PubMed

    Sargus-Patino, Catherine N; Wright, Elane C; Plautz, Sarah A; Miles, Jeremy R; Vallet, Jeff L; Pannier, Angela K

    2014-08-01

    Between Days 10 and 12 of gestation, porcine embryos undergo a dramatic morphological change, known as elongation, with a corresponding increase in oestrogen production that triggers maternal recognition of pregnancy. Elongation deficiencies contribute to embryonic loss, but exact mechanisms of elongation are poorly understood due to the lack of an effective in vitro culture system. Our objective was to use alginate hydrogels as three-dimensional scaffolds that can mechanically support the in vitro development of preimplantation porcine embryos. White cross-bred gilts were bred at oestrus (Day 0) to Duroc boars and embryos were recovered on Days 9, 10 or 11 of gestation. Spherical embryos were randomly assigned to be encapsulated within double-layered 0.7% alginate beads or remain as non-encapsulated controls (ENC and CONT treatment groups, respectively) and were cultured for 96h. Every 24h, half the medium was replaced with fresh medium and an image of each embryo was recorded. At the termination of culture, embryo images were used to assess morphological changes and cell survival. 17β-Oestradiol levels were measured in the removed media by radioimmunoassay. Real-time polymerase chain reaction was used to analyse steroidogenic transcript expression at 96h in ENC and CONT embryos, as well as in vivo-developed control embryos (i.e. spherical, ovoid and tubular). Although no differences in cell survival were observed, 32% (P<0.001) of the surviving ENC embryos underwent morphological changes characterised by tubal formation with subsequent flattening, whereas none of the CONT embryos exhibited morphological changes. Expression of steroidogenic transcripts STAR, CYP11A1 and CYP19A1 was greater (P<0.07) in ENC embryos with morphological changes (ENC+) compared with CONT embryos and ENC embryos with no morphological changes (ENC-), and was more similar to expression of later-stage in vivo-developed controls. Furthermore, a time-dependent increase (P<0.001) in 17

  1. In vitro development of preimplantation porcine embryos using alginate hydrogels as a three-dimensional extracellular matrix.

    PubMed

    Sargus-Patino, Catherine N; Wright, Elane C; Plautz, Sarah A; Miles, Jeremy R; Vallet, Jeff L; Pannier, Angela K

    2014-08-01

    Between Days 10 and 12 of gestation, porcine embryos undergo a dramatic morphological change, known as elongation, with a corresponding increase in oestrogen production that triggers maternal recognition of pregnancy. Elongation deficiencies contribute to embryonic loss, but exact mechanisms of elongation are poorly understood due to the lack of an effective in vitro culture system. Our objective was to use alginate hydrogels as three-dimensional scaffolds that can mechanically support the in vitro development of preimplantation porcine embryos. White cross-bred gilts were bred at oestrus (Day 0) to Duroc boars and embryos were recovered on Days 9, 10 or 11 of gestation. Spherical embryos were randomly assigned to be encapsulated within double-layered 0.7% alginate beads or remain as non-encapsulated controls (ENC and CONT treatment groups, respectively) and were cultured for 96h. Every 24h, half the medium was replaced with fresh medium and an image of each embryo was recorded. At the termination of culture, embryo images were used to assess morphological changes and cell survival. 17β-Oestradiol levels were measured in the removed media by radioimmunoassay. Real-time polymerase chain reaction was used to analyse steroidogenic transcript expression at 96h in ENC and CONT embryos, as well as in vivo-developed control embryos (i.e. spherical, ovoid and tubular). Although no differences in cell survival were observed, 32% (P<0.001) of the surviving ENC embryos underwent morphological changes characterised by tubal formation with subsequent flattening, whereas none of the CONT embryos exhibited morphological changes. Expression of steroidogenic transcripts STAR, CYP11A1 and CYP19A1 was greater (P<0.07) in ENC embryos with morphological changes (ENC+) compared with CONT embryos and ENC embryos with no morphological changes (ENC-), and was more similar to expression of later-stage in vivo-developed controls. Furthermore, a time-dependent increase (P<0.001) in 17

  2. Bioprinted Scaffolds for Cartilage Tissue Engineering.

    PubMed

    Kang, Hyun-Wook; Yoo, James J; Atala, Anthony

    2015-01-01

    Researchers are focusing on bioprinting technology as a viable option to overcome current difficulties in cartilage tissue engineering. Bioprinting enables a three-dimensional (3-D), free-form, computer-designed structure using biomaterials, biomolecules, and/or cells. The inner and outer shape of a scaffold can be controlled by this technology with great precision. Here, we introduce a hybrid bioprinting technology that is a co-printing process of multiple materials including high-strength synthetic polymer and cell-laden hydrogel. The synthetic polymer provides mechanical support for shape maintenance and load bearing, while the hydrogel provides the biological environment for artificial cartilage regeneration. This chapter introduces the procedures for printing of a 3-D scaffold using our hybrid bioprinting technology and includes the source materials for preparation of 3-D printing. PMID:26445837

  3. Methylene blue adsorption on graphene oxide/calcium alginate composites.

    PubMed

    Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Wang, Yonghao; Wu, Shaoling; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

    2013-06-01

    Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81 mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature.

  4. Fundamental Characteristics of Bioprint on Calcium Alginate Gel

    NASA Astrophysics Data System (ADS)

    Umezu, Shinjiro; Hatta, Tatsuru; Ohmori, Hitoshi

    2013-05-01

    The goal of this study is to fabricate precision three-dimensional (3D) biodevices those are micro fluidics and artificial organs utilizing digital fabrication. Digital fabrication is fabrication method utilizing inkjet technologies. Electrostatic inkjet is one of the inkjet technologies. The electrostatic inkjet method has following two merits; those are high resolution to print and ability to eject highly viscous liquid. These characteristics are suitable to print biomaterials precisely. We are now applying for bioprint. In this paper, the electrostatic inkjet method is applied for fabrication of 3D biodevices that has cave like blood vessel. When aqueous solution of sodium alginate is printed to aqueous solution of calcium chloride, calcium alginate is produced. 3D biodevices are fabricated in case that calcium alginate is piled.

  5. Alginate based polyurethanes: A review of recent advances and perspective.

    PubMed

    Zia, Khalid Mahmood; Zia, Fatima; Zuber, Mohammad; Rehman, Saima; Ahmad, Mirza Nadeem

    2015-08-01

    The trend of using biopolymers in combination with synthetic polymers was increasing rapidly from last two or three decades. Polysaccharide based biopolymers especially starch, cellulose, chitin, chitosan, alginate, etc. found extensive applications for different industrial uses, as they are biocompatible, biodegradable, bio-renewable resources and chiefly environment friendly. Segment block copolymer character of polyurethanes that endows them a broad range of versatility in terms of tailoring their properties was employed in conjunction with various natural polymers resulted in modified biomaterials. Alginate is biodegradable, biocompatible, bioactive, less toxic and low cost anionic polysaccharide, as a part of structural component of bacteria and brown algae (sea weed) is quite abundant in nature. It is used in combination with polyurethanes to form elastomers, nano-composites, hydrogels, etc. that especially revolutionized the food and biomedical industries. The review summarized the development in alginate based polyurethanes with their potential applications.

  6. Effects of ambroxol on alginate of mature Pseudomonas aeruginosa biofilms.

    PubMed

    Li, Fang; Yu, Jialin; Yang, Hua; Wan, Zhenyan; Bai, Dan

    2008-07-01

    Biofilm-forming bacteria Pseudomonas aeruginosa is a common pathogen in mechanically ventilated newborns, which can cause life-threatening infections. Alginate of mucoid Pseudomonas aeruginosa biofilms is considered an important virulence factor which contributes to the resistance to antibiotics. Traditionally, ambroxol is widely used in newborns with lung problems as a mucolytic agent and antioxidant agent as well. And there are few studies that demonstrated the anti-biofilm activity of ambroxol. In this study, we found that ambroxol can affect the structure of mucoid Pseudomonas aeruginosa biofilms. Further, we found that ambroxol reduces the production of alginate, the expression of the important genes and the activity of key enzyme guanosine diphospho-D-mannose dehydrogenase (GDP-mannose dehydrogenase; GMD) which were involved in alginate biosynthesis.

  7. Optimization of alpha-amylase immobilization in calcium alginate beads.

    PubMed

    Ertan, Figen; Yagar, Hulya; Balkan, Bilal

    2007-01-01

    alpha-Amylase enzyme was produced by Aspergillus sclerotiorum under SSF conditions, and immobilized in calcium alginate beads. Effects of immobilization conditions, such as alginate concentration, CaCl(2) concentration, amount of loading enzyme, bead size, and amount of beads, on enzymatic activity were investigated. Optimum alginate and CaCl(2) concentration were found to be 3% (w/v). Using a loading enzyme concentration of 140 U mL(-1), and bead (diameter 3 mm) amount of 0.5 g, maximum enzyme activity was observed. Beads prepared at optimum immobilization conditions were suitable for up to 7 repeated uses, losing only 35% of their initial activity. Among the various starches tested, the highest enzyme activity (96.2%) was determined in soluble potato starch hydrolysis for 120 min at 40 degrees C.

  8. Ocular hypotensive efficacy and safety of once daily carteolol alginate

    PubMed Central

    Demailly, P.; Allaire, C.; Trinquand, C.

    2001-01-01

    BACKGROUND/AIM—Carteolol is a β adrenoceptor antagonist used topically to reduce intraocular pressure, typically twice daily. In an effort to provide a once daily dosing regimen, carteolol was formulated with 1% alginic acid. The objective of this study was to evaluate the efficacy and safety of carteolol alginate solution in comparison with standard carteolol solution.
METHODS—This was a double masked, parallel group, multicentre study. Patients with ocular hypertension or open angle glaucoma (n=235) were randomly assigned to receive either carteolol alginate four times daily or standard carteolol solution, twice daily. The masking was maintained through the use of a vehicle in the evening for the alginate group. Patients were evaluated at baseline, 15, 60, and 120 days.
RESULTS—At 0900 (presumed trough) on day 60, mean reductions in intraocular pressure (IOP) from baseline were 6.09 (SD 2.97) and 6.09 (3.18) mm Hg for the standard carteolol and alginate, respectively. At 1100 (presumed peak), mean reductions were 6.51 (2.53) and 6.47 (2.76) mm Hg, respectively. Results were similar at other times (day 15 and day 120). The most common side effect was transient stinging on instillation of drops, which did not differ significantly between groups. There were no differences of note in other ocular or systemic signs or symptoms.
CONCLUSION—The new alginate formulation of carteolol 2% given once daily was as effective as standard carteolol 2% given twice daily with no meaningful differences regarding safety.

 PMID:11466245

  9. Diffusion in and around alginate and chitosan films with embedded sub-millimeter voids.

    PubMed

    Patra, Subhajit; Bal, Dharmendra Kumar; Ganguly, Somenath

    2016-02-01

    Hydrogel scaffolds from biopolymers have potential use in the controlled release of drugs, and as 3-D structure for the formation of tissue matrix. This article describes the solute release behavior of alginate and chitosan films with embedded voids of sub-millimeter dimensions. Nitrogen gas was bubbled in a fluidic arrangement to generate bubbles, prior to the crosslinking. The crosslinked gel was dried in a vacuum oven, and subsequently, soaked in Vitamin B-12 solution. The dimensions of the voids immediately after the cross-linking of gel, and also after complete drying were obtained using a digital microscope and scanning electron microscope respectively. The porosity of the gel was measured gravimetrically. The release of Vitamin B-12 in PBS buffer on a shaker was studied. The release experiments were repeated at an elevated temperature of 37°C in the presence of lysozyme. The diffusion coefficient within the gel layer and the mass transfer coefficient at the interface with the bulk-liquid were estimated using a mathematical model. For comparison, the experiment was repeated with a film that does not have any embedded void. The enhancement in diffusion coefficient due to the presence of voids is discussed in this article.

  10. Natural polyelectrolyte self-assembled multilayers based on collagen and alginate: stability and cytocompatibility.

    PubMed

    Li, Wenxing; Zhao, Peng; Lin, Chao; Wen, Xuejun; Katsanevakis, Eleni; Gero, Decher; Félix, Olivier; Liu, Yuehua

    2013-08-12

    Scientific interest in the self-assembly of collagen composite films has been increasing for their potential application in constructing bioactive materials. Here we report a highly stable and cytocompatible collagen/alginate (COL/ALG) ultrathin film, which was linearly fabricated via a layer-by-layer self-assembled technique. The variation in morphology and thickness of the films in air and in solutions with different pH and ion values were tested by atomic force microscopy. Results showed that the solutions with high pH values or solutions that contained electrolytes would disintegrate the film, while films with that were cross-linked for a long time prevented the dissolution and contributed to stability maintenance of the films. Interestingly, the COL/ALG coating not only improved the adhesion and proliferation of the human periodontal ligament cells, but also modified the morphology and migration of cells on the surface of glass and poly-L-lactic acid (PLA) electrospun scaffolds. In conclusion, the COL/ALG ultrathin films were highly stable and cytocompatible and could be easily fabricated by the cost-effective self-assembled technique presented. The findings of this study have the potential to play an important role in the surface modification of biomaterials. PMID:23782041

  11. Chitosan and alginate biopolymer membranes for remediation of contaminated water with herbicides.

    PubMed

    Agostini de Moraes, Mariana; Cocenza, Daniela Sgarbi; da Cruz Vasconcellos, Fernando; Fraceto, Leonardo Fernandes; Beppu, Marisa Masumi

    2013-12-15

    This study investigated the adsorption behavior of the herbicides diquat, difenzoquat and clomazone on biopolymer membranes prepared with alginate and chitosan (pristine and multi-layer model) for contaminated water remediation applications. Herbicides, at concentrations ranging from 5 μM to 200 μM, were adsorbed in either pure alginate, pure chitosan or a bilayer membrane composed of chitosan/alginate. No adsorption of clomazone was observed on any of the membranes, probably due to lack of electrostatic interactions between the herbicide and the membranes. Diquat and difenzoquat were only adsorbed on the alginate and chitosan/alginate membranes, indicating that this adsorption takes place in the alginate layer. At a concentration of 50 μM, diquat adsorption reaches ca. 95% after 120 min on both the alginate and chitosan/alginate membranes. The adsorption of difenzoquat, at the same concentration, reaches ca. 62% after 120 min on pure alginate membranes and ca. 12% on chitosan/alginate bilayer membranes. The adsorption isotherms for diquat and difenzoquat were further evaluated using the isotherm models proposed by Langmuir and by Freundlich, where the latter represented the best-fit model. Results indicate that adsorption occurs via coulombic interactions between the herbicides and alginate and is strongly related to the electrostatic charge, partition coefficients and dissociation constants of the herbicides. Biopolymer based membranes present novel systems for the removal of herbicides from contaminated water sources and hold great promise in the field of environmental science and engineering.

  12. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    PubMed

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed.

  13. Effect of chitosan coating on a bacteria-based alginate microrobot.

    PubMed

    Park, Sung Jun; Lee, Yu Kyung; Cho, Sunghoon; Uthaman, Saji; Park, In-Kyu; Min, Jung-Joon; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2015-04-01

    To develop an efficient bacteria-based microrobot, first, therapeutic bacteria should be encapsulated into microbeads using biodegradable and biocompatible materials; second, the releasing rate of the encapsulated bacteria for theragnostic function should be regulated; and finally, flagellated bacteria should be attached on the microbeads to ensure the motility of the microrobot. For the therapeutic bacteria encapsulation, an alginate can be a promising candidate as a biodegradable and biocompatible material. Owing to the non-regulated releasing rate of the encapsulated bacteria in alginate microbeads and the weak attachment of flagellated bacteria on the surface of alginate microbeads, however, the alginate microbeads cannot be used as effective cargo for a bacteria-based microrobot. In this paper, to enhance the stability of the bacteria encapsulation and the adhesion of flagellated bacteria in alginate microbeads, we performed a surface modification of alginate microbeads using chitosan coating. The bacteria-encapsulated alginate microbeads with 1% chitosan coating maintained their structural integrity up to 72 h, whereas the control alginate microbead group without chitosan coating showed severe degradations after 24 h. The chitosan coating in alginate microbeads shows the enhanced attachment of flagellated bacteria on the surface of alginate microbeads. The bacteria-actuated microrobot with the enhanced flagellated bacteria attachment could show approximately 4.2 times higher average velocities than the control bacteria-actuated microrobot without chitosan coating. Consequently, the surface modification using chitosan coating enhanced the structural stability and the motility of the bacteria-based alginate microrobots.

  14. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    PubMed

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed. PMID:26794953

  15. Effects of composition and structure of alginates on adsorption of divalent metals

    NASA Astrophysics Data System (ADS)

    Nai-Yu, Zheng; Yan-Xia, Zhang; Xiao, Fan; Li-Jun, Han

    1994-03-01

    Results of a series of experiments (on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of different composition and block structure) conducted in this systematic study of the effects of the composition and structure of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of the M/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu2+ ion decrease with the increase of the G-block or the average length of the G-block(bar N_G ) and the total adsorption capacity of alginic acid is found to vary in the same order as the F MM(diad frequency) in alginate in the mixed solution of Sr2+, Ba2+ and Cd2+.

  16. The antimicrobial efficacy of a silver alginate dressing against a broad spectrum of clinically relevant wound isolates.

    PubMed

    Percival, Steven L; Slone, Will; Linton, Sara; Okel, Tyler; Corum, Linda; Thomas, John G

    2011-06-01

    Wound dressings impregnated with silver have a role to play in aiding to reduce both the dressing and wound microbial bioburden. It is therefore imperative that antimicrobial wound dressings have efficacy on a broad range of clinical significant microorganisms. Accordingly, this study aimed to determine the antimicrobial efficacy of a silver alginate dressing against 115 wound isolates that had been isolated routinely from patients at West Virginia University Hospital. Standardised corrected zones of inhibition (CZOIs) were performed on all clinical isolates. It was found that the silver alginate dressing was able to inhibit the growth of all microorganisms tested. In particular, the silver alginate dressing inhibited the growth of Candida albicans and yeasts with CZOI of 3-11·5 mm. All meticillin-resistant Staphylococcus aureus (MRSA) strains were found to be sensitive to the silver alginate dressing with a CZOI range calculated at 3-7·8 mm. Sensitivity to the silver alginate dressing was also evident for S. aureus and vancomycin-resistant Enterococci. CZOIs of 4·25 mm were calculated for Enterococcus faecium and 9·8 mm for viridans streptococcus. The bacteria which demonstrated the highest tolerance to ionic silver included Enterobacter cloacae and Acinetobacter baumannii. Contrary to this the most responsive microorganisms to ionic silver included strains of staphylococci, viridans streptococcus and Candida albicans. No antibiotic-resistant isolates, as identified by Kirby Bauer Clinical Laboratory Standards Institute classification system, were found to be resistant to ionic silver. When a selected number of microorganisms were grown in the biofilm phenotypic state enhanced tolerance to silver was observed, compared to their non biofilm counterparts. Overall, this study has demonstrated the broad antimicrobial activity of a silver alginate dressing on wound isolates grown in the non biofilm and biofilm state. This finding is clinically relevant as both the

  17. Alginate gel microwell arrays using electrodeposition for three-dimensional cell culture.

    PubMed

    Ozawa, Fumisato; Ino, Kosuke; Arai, Toshiharu; Ramón-Azcón, Javier; Takahashi, Yasufumi; Shiku, Hitoshi; Matsue, Tomokazu

    2013-08-01

    In this study, we developed a novel method for fabricating microwell arrays constructed from alginate gels, and the alginate gel microwells were used for three-dimensional (3D) cell culture. The alginate gel microwells were fabricated on a patterned ITO electrode using alginate gel electrodeposition. Embryonic stem (ES) cells or hepatocellular carcinoma cells (HepG2) were cultured in the alginate gel microwells containing 3T3 cells. During the culture, embryoid bodies (EBs) or HepG2 spheroids were successfully fabricated in the alginate gel microwells. The oxygen consumption of the EBs indicated that they were successfully cultured. Liver-specific gene expressions of the HepG2 spheroids apparently increased by performing 3D co-culture in the microwell arrays with 3T3 cells. These results show that the alginate gel microwells are a useful 3D culture system.

  18. Hydrophobic modification of sodium alginate and its application in drug controlled release.

    PubMed

    Yao, Bolong; Ni, Caihua; Xiong, Cheng; Zhu, Changping; Huang, Bo

    2010-05-01

    Sodium alginate was hydrophobically modified by coupling of polybutyl methacrylate onto the alginate. The polybutyl methacrylate was previously prepared through polymerization of butyl methacrylate in the presence of 2-amino-ethanethiol as a chain transfer agent. The structure of the product was characterized by Fourier-transformed infrared spectrometry, nuclear magnetic resonance ((1)HNMR) and thermogravimetry. The result of fluorescence analysis showed that the hydrophobicity of the modified alginate was obviously increased. The modified alginate conjugate was used for immobilization of bovine serum albumin in the presence of calcium chloride. In addition, the release behavior of the drug-loaded alginate in deionized water and Tris-HCl buffer solution (pH 7.2) was investigated. It was found that the modified sodium alginate possessed prolonged release behavior compared to unmodified sodium alginate, and it had potential application in controlled release as a drug carrier.

  19. Immobilization of a Plant Lipase from Pachira aquatica in Alginate and Alginate/PVA Beads

    PubMed Central

    Bonine, Bárbara M.; Polizelli, Patricia Peres; Bonilla-Rodriguez, Gustavo O.

    2014-01-01

    This study reports the immobilization of a new lipase isolated from oleaginous seeds of Pachira aquatica, using beads of calcium alginate (Alg) and poly(vinyl alcohol) (PVA). We evaluated the morphology, number of cycles of reuse, optimum temperature, and temperature stability of both immobilization methods compared to the free enzyme. The immobilized enzymes were more stable than the free enzyme, keeping 60% of the original activity after 4 h at 50°C. The immobilized lipase was reused several times, with activity decreasing to approximately 50% after 5 cycles. Both the free and immobilized enzymes were found to be optimally active between 30 and 40°C. PMID:24818012

  20. The influence of polymeric component of bioactive glass-based nanocomposite paste on its rheological behaviors and in vitro responses: hyaluronic acid versus sodium alginate.

    PubMed

    Sohrabi, Mehri; Hesaraki, Saeed; Kazemzadeh, Asghar

    2014-04-01

    Different biocomposite pastes were prepared from a solid phase that was nanoparticles of sol-gel-derived bioactive glass and different liquid phases including 3% hyaluronic acid solution, sodium alginate solutions (3% and 10 %) or mixtures of hyaluronic acid and sodium alginate (3% or 10 %) solutions in 50:50 volume ratio. Rheological properties of the pastes were measured in both rotatory and oscillatory modes. The washout behavior and in vitro apatite formation of the pastes were determined by soaking them in simulated body fluid under dynamic situation for 14 days. The proliferation and alkaline phosphatase activity of MG-63 osteoblastic cells were also determined using extracts of the pastes. All pastes could be easily injected from the standard syringes with different tip diameters. All pastes exhibited visco-elastic character, but a nonthixotropic paste was obtained using hyaluronic acid in which the loss modulus was higher than the storage modulus. The thixotropy and storage modulus were increasingly improved by adding/using sodium alginate as mixing liquid. Moreover, the pastes in which the liquid phase was sodium alginate or mixture of hyaluronic acid and 10% sodium alginate solution revealed better apatite formation ability and washout resistance than that made of hyaluronic acid alone. No cytotoxicity effects were observed by extracts of the pastes on osteoblasts but better alkaline phosphatase activity was found for the pastes containing hyaluronic acid. Overall, injectable biocomposites can be produced by mixing bioactive glass nanoparticles and sodium alginate/hyaluronic acid polymers. They are potentially useful for hard and even soft tissues treatments. PMID:24123918

  1. Electrospun SF/PLCL nanofibrous membrane: a potential scaffold for retinal progenitor cell proliferation and differentiation

    PubMed Central

    Zhang, Dandan; Ni, Ni; Chen, Junzhao; Yao, Qinke; Shen, Bingqiao; Zhang, Yi; Zhu, Mengyu; Wang, Zi; Ruan, Jing; Wang, Jing; Mo, Xiumei; Shi, Wodong; Ji, Jing; Fan, Xianqun; Gu, Ping

    2015-01-01

    Biocompatible polymer scaffolds are promising as potential carriers for the delivery of retinal progenitor cells (RPCs) in cell replacement therapy for the repair of damaged or diseased retinas. The primary goal of the present study was to investigate the effects of blended electrospun nanofibrous membranes of silk fibroin (SF) and poly(L-lactic acid-co-ε-caprolactone) (PLCL), a novel scaffold, on the biological behaviour of RPCs in vitro. To assess the cell-scaffold interaction, RPCs were cultured on SF/PLCL scaffolds for indicated durations. Our data revealed that all the SF/PLCL scaffolds were thoroughly cytocompatible, and the SF:PLCL (1:1) scaffolds yielded the best RPC growth. The in vitro proliferation assays showed that RPCs proliferated more quickly on the SF:PLCL (1:1) than on the other scaffolds and the control. Quantitative polymerase chain reaction (qPCR) and immunocytochemistry analyses demonstrated that RPCs grown on the SF:PLCL (1:1) scaffolds preferentially differentiated toward retinal neurons, including, most interestingly, photoreceptors. In summary, we demonstrated that the SF:PLCL (1:1) scaffolds can not only markedly promote RPC proliferation with cytocompatibility for RPC growth but also robustly enhance RPCs’ differentiation toward specific retinal neurons of interest in vitro, suggesting that SF:PLCL (1:1) scaffolds may have potential applications in retinal cell replacement therapy in the future. PMID:26395224

  2. Electrospun SF/PLCL nanofibrous membrane: a potential scaffold for retinal progenitor cell proliferation and differentiation.

    PubMed

    Zhang, Dandan; Ni, Ni; Chen, Junzhao; Yao, Qinke; Shen, Bingqiao; Zhang, Yi; Zhu, Mengyu; Wang, Zi; Ruan, Jing; Wang, Jing; Mo, Xiumei; Shi, Wodong; Ji, Jing; Fan, Xianqun; Gu, Ping

    2015-01-01

    Biocompatible polymer scaffolds are promising as potential carriers for the delivery of retinal progenitor cells (RPCs) in cell replacement therapy for the repair of damaged or diseased retinas. The primary goal of the present study was to investigate the effects of blended electrospun nanofibrous membranes of silk fibroin (SF) and poly(L-lactic acid-co-ε-caprolactone) (PLCL), a novel scaffold, on the biological behaviour of RPCs in vitro. To assess the cell-scaffold interaction, RPCs were cultured on SF/PLCL scaffolds for indicated durations. Our data revealed that all the SF/PLCL scaffolds were thoroughly cytocompatible, and the SF:PLCL (1:1) scaffolds yielded the best RPC growth. The in vitro proliferation assays showed that RPCs proliferated more quickly on the SF:PLCL (1:1) than on the other scaffolds and the control. Quantitative polymerase chain reaction (qPCR) and immunocytochemistry analyses demonstrated that RPCs grown on the SF:PLCL (1:1) scaffolds preferentially differentiated toward retinal neurons, including, most interestingly, photoreceptors. In summary, we demonstrated that the SF:PLCL (1:1) scaffolds can not only markedly promote RPC proliferation with cytocompatibility for RPC growth but also robustly enhance RPCs' differentiation toward specific retinal neurons of interest in vitro, suggesting that SF:PLCL (1:1) scaffolds may have potential applications in retinal cell replacement therapy in the future. PMID:26395224

  3. Biodegradable Fibrous Scaffolds with Diverse Properties by Electrospinning Candidates from a Combinatorial Macromer Library

    PubMed Central

    Metter, Robert B.; Ifkovits, Jamie L.; Hou, Kevin; Vincent, Ludovic; Hsu, Benjamin; Wang, Louis; Mauck, Robert L.; Burdick, Jason A.

    2009-01-01

    The properties of electrospun fibrous scaffolds, including degradation, mechanics and cellular interactions, are important for their use in tissue engineering applications. Although some diversity has been obtained previously in fibrous scaffolds, optimization of scaffold properties relies on iterative techniques in both polymer synthesis and processing. Here, we electrospun candidates from a combinatorial library of biodegradable and photopolymerizable poly(β-amino ester)s (PBAEs) to show that the diversity in properties found in this library is retained when processed into fibrous scaffolds. Specifically, three PBAE macromers were electrospun into scaffolds and possessed similar initial mechanical properties, but exhibited mass loss ranging from rapid (complete degradation within ∼2 weeks) to moderate (complete degradation within ∼ 3 months) to slow (only partial degradation after 3 months). These trends in mechanics and degradation mimicked what was previously observed in the bulk polymers. Although cellular adhesion was dependent on the polymer composition in films, adhesion to scaffolds that were electrospun with gelatin was similar on all formulations and controls. To further illustrate the diverse properties that are attainable in these systems, the fastest and slowest degrading polymers were electrospun together into one scaffold, but as distinct fiber populations. This dual-polymer scaffold exhibited behavior in mass loss and mechanics with time that fell between the single-polymer scaffolds. In general, this work indicates that combinatorial libraries may be an important source of information and specific polymer compositions for the fabrication of electrospun fibrous scaffolds with tunable properties. PMID:19853066

  4. Characterisation of the surface structure of 3D printed scaffolds for cell infiltration and surgical suturing.

    PubMed

    Ruiz-Cantu, Laura; Gleadall, Andrew; Faris, Callum; Segal, Joel; Shakesheff, Kevin; Yang, Jing

    2016-03-01

    3D printing is of great interest for tissue engineering scaffolds due to the ability to form complex geometries and control internal structures, including porosity and pore size. The porous structure of scaffolds plays an important role in cell ingrowth and nutrition infusion. Although the internal porosity and pore size of 3D printed scaffolds have been frequently studied, the surface porosity and pore size, which are critical for cell infiltration and mass transport, have not been investigated. The surface geometry can differ considerably from the internal scaffold structure depending on the 3D printing process. It is vital to be able to control the surface geometry of scaffolds as well as the internal structure to fabricate optimal architectures. This work presents a method to control the surface porosity and pore size of 3D printed scaffolds. Six scaffold designs have been printed with surface porosities ranging from 3% to 21%. We have characterised the overall scaffold porosity and surface porosity using optical microscopy and microCT. It has been found that surface porosity has a significant impact on cell infiltration and proliferation. In addition, the porosity of the surface has been found to have an effect on mechanical properties and on the forces required to penetrate the scaffold with a surgical suturing needle. To the authors' knowledge, this study is the first to investigate the surface geometry of extrusion-based 3D printed scaffolds and demonstrates the importance of surface geometry in cell infiltration and clinical manipulation. PMID:26930179

  5. Characterisation of the surface structure of 3D printed scaffolds for cell infiltration and surgical suturing.

    PubMed

    Ruiz-Cantu, Laura; Gleadall, Andrew; Faris, Callum; Segal, Joel; Shakesheff, Kevin; Yang, Jing

    2016-03-01

    3D printing is of great interest for tissue engineering scaffolds due to the ability to form complex geometries and control internal structures, including porosity and pore size. The porous structure of scaffolds plays an important role in cell ingrowth and nutrition infusion. Although the internal porosity and pore size of 3D printed scaffolds have been frequently studied, the surface porosity and pore size, which are critical for cell infiltration and mass transport, have not been investigated. The surface geometry can differ considerably from the internal scaffold structure depending on the 3D printing process. It is vital to be able to control the surface geometry of scaffolds as well as the internal structure to fabricate optimal architectures. This work presents a method to control the surface porosity and pore size of 3D printed scaffolds. Six scaffold designs have been printed with surface porosities ranging from 3% to 21%. We have characterised the overall scaffold porosity and surface porosity using optical microscopy and microCT. It has been found that surface porosity has a significant impact on cell infiltration and proliferation. In addition, the porosity of the surface has been found to have an effect on mechanical properties and on the forces required to penetrate the scaffold with a surgical suturing needle. To the authors' knowledge, this study is the first to investigate the surface geometry of extrusion-based 3D printed scaffolds and demonstrates the importance of surface geometry in cell infiltration and clinical manipulation.

  6. Nitric Oxide Release Part I. Macromolecular Scaffolds

    PubMed Central

    Riccio, Daniel A.; Schoenfisch, Mark H.

    2012-01-01

    Summary The roles of nitric oxide (NO) in physiology and pathophysiology merit the use of NO as a therapeutic for certain biomedical applications. Unfortunately, limited NO payloads, too rapid NO release, and the lack of targeted NO delivery have hindered the clinical utility of NO gas and low molecular weight NO donor compounds. A wide-variety of NO-releasing macromolecular scaffolds has thus been developed to improve NO’s pharmacological potential. In this tutorial review, we provide an overview of the most promising NO release scaffolds including protein, organic, inorganic, and hybrid organic-inorganic systems. The NO release vehicles selected for discussion were chosen based on their enhanced NO storage, tunable NO release characteristics, and potential as therapeutics. PMID:22362355

  7. Exploring the scaffold universe of kinase inhibitors.

    PubMed

    Hu, Ye; Bajorath, Jürgen

    2015-01-01

    The scaffold concept was applied to systematically determine, analyze, and compare core structures of kinase inhibitors. From publicly available inhibitors of the human kinome, scaffolds and cyclic skeletons were systematically extracted and organized taking activity data, structural relationships, and retrosynthetic criteria into account. Scaffold coverage varied greatly across the kinome, and many scaffolds representing compounds with different activity profiles were identified. The majority of kinase inhibitor scaffolds were involved in well-defined yet distinct structural relationships, which had different consequences on compound activity. Scaffolds exclusively representing highly potent compounds were identified as well as structurally analogous scaffolds with very different degrees of promiscuity. Scaffold relationships presented herein suggest a variety of hypotheses for inhibitor design. Our detailed organization of the kinase inhibitor scaffold universe with respect to different activity and structural criteria, all scaffolds, and the original compound data assembled for our analysis are made freely available.

  8. Evaluation of Osteoconductive Scaffolds in the Canine Femoral Multi-Defect Model

    PubMed Central

    Luangphakdy, Viviane; Walker, Esteban; Shinohara, Kentaro; Pan, Hui; Hefferan, Theresa; Bauer, Thomas W.; Stockdale, Linda; Saini, Sunil; Dadsetan, Mahrokh; Runge, M. Brett; Vasanji, Amit; Griffith, Linda; Yaszemski, Michael

    2013-01-01

    Treatment of large segmental bone defects remains an unsolved clinical challenge, despite a wide array of existing bone graft materials. This project was designed to rapidly assess and compare promising biodegradable osteoconductive scaffolds for use in the systematic development of new bone regeneration methodologies that combine scaffolds, sources of osteogenic cells, and bioactive scaffold modifications. Promising biomaterials and scaffold fabrication methods were identified in laboratories at Rutgers, MIT, Integra Life Sciences, and Mayo Clinic. Scaffolds were fabricated from various materials, including poly(L-lactide-co-glycolide) (PLGA), poly(L-lactide-co-ɛ-caprolactone) (PLCL), tyrosine-derived polycarbonate (TyrPC), and poly(propylene fumarate) (PPF). Highly porous three-dimensional (3D) scaffolds were fabricated by 3D printing, laser stereolithography, or solvent casting followed by porogen leaching. The canine femoral multi-defect model was used to systematically compare scaffold performance and enable selection of the most promising substrate(s) on which to add cell sourcing options and bioactive surface modifications. Mineralized cancellous allograft (MCA) was used to provide a comparative reference to the current clinical standard for osteoconductive scaffolds. Percent bone volume within the defect was assessed 4 weeks after implantation using both MicroCT and limited histomorphometry. Bone formed at the periphery of all scaffolds with varying levels of radial ingrowth. MCA produced a rapid and advanced stage of bone formation and remodeling throughout the defect in 4 weeks, greatly exceeding the performance of all polymer scaffolds. Two scaffold constructs, TyrPCPL/TCP and PPF4SLA/HAPLGA Dip, proved to be significantly better than alternative PLGA and PLCL scaffolds, justifying further development. MCA remains the current standard for osteoconductive scaffolds. PMID:23215980

  9. PLDLA/PCL-T Scaffold for Meniscus Tissue Engineering.

    PubMed

    Esposito, Andrea Rodrigues; Moda, Marlon; Cattani, Silvia Mara de Melo; de Santana, Gracy Mara; Barbieri, Juliana Abreu; Munhoz, Monique Moron; Cardoso, Túlio Pereira; Barbo, Maria Lourdes Peris; Russo, Teresa; D'Amora, Ugo; Gloria, Antonio; Ambrosio, Luigi; Duek, Eliana Aparecida de Rezende

    2013-04-01

    The inability of the avascular region of the meniscus to regenerate has led to the use of tissue engineering to treat meniscal injuries. The aim of this study was to evaluate the ability of fibrochondrocytes preseeded on PLDLA/PCL-T [poly(L-co-D,L-lactic acid)/poly(caprolactone-triol)] scaffolds to stimulate regeneration of the whole meniscus. Porous PLDLA/PCL-T (90/10) scaffolds were obtained by solvent casting and particulate leaching. Compressive modulus of 9.5±1.0 MPa and maximum stress of 4.7±0.9 MPa were evaluated. Fibrochondrocytes from rabbit menisci were isolated, seeded directly on the scaffolds, and cultured for 21 days. New Zealand rabbits underwent total meniscectomy, after which implants consisting of cell-free scaffolds or cell-seeded scaffolds were introduced into the medial knee meniscus; the negative control group consisted of rabbits that received no implant. Macroscopic and histological evaluations of the neomeniscus were performed 12 and 24 weeks after implantation. The polymer scaffold implants adapted well to surrounding tissues, without apparent rejection, infection, or chronic inflammatory response. Fibrocartilaginous tissue with mature collagen fibers was observed predominantly in implants with seeded scaffolds compared to cell-free implants after 24 weeks. Similar results were not observed in the control group. Articular cartilage was preserved in the polymeric implants and showed higher chondrocyte cell number than the control group. These findings show that the PLDLA/PCL-T 90/10 scaffold has potential for orthopedic applications since this material allowed the formation of fibrocartilaginous tissue, a structure of crucial importance for repairing injuries to joints, including replacement of the meniscus and the protection of articular cartilage from degeneration.

  10. PLDLA/PCL-T Scaffold for Meniscus Tissue Engineering

    PubMed Central

    Moda, Marlon; Cattani, Silvia Mara de Melo; de Santana, Gracy Mara; Barbieri, Juliana Abreu; Munhoz, Monique Moron; Cardoso, Túlio Pereira; Barbo, Maria Lourdes Peris; Russo, Teresa; D'Amora, Ugo; Gloria, Antonio; Ambrosio, Luigi; Duek, Eliana Aparecida de Rezende

    2013-01-01

    Abstract The inability of the avascular region of the meniscus to regenerate has led to the use of tissue engineering to treat meniscal injuries. The aim of this study was to evaluate the ability of fibrochondrocytes preseeded on PLDLA/PCL-T [poly(L-co-D,L-lactic acid)/poly(caprolactone-triol)] scaffolds to stimulate regeneration of the whole meniscus. Porous PLDLA/PCL-T (90/10) scaffolds were obtained by solvent casting and particulate leaching. Compressive modulus of 9.5±1.0 MPa and maximum stress of 4.7±0.9 MPa were evaluated. Fibrochondrocytes from rabbit menisci were isolated, seeded directly on the scaffolds, and cultured for 21 days. New Zealand rabbits underwent total meniscectomy, after which implants consisting of cell-free scaffolds or cell-seeded scaffolds were introduced into the medial knee meniscus; the negative control group consisted of rabbits that received no implant. Macroscopic and histological evaluations of the neomeniscus were performed 12 and 24 weeks after implantation. The polymer scaffold implants adapted well to surrounding tissues, without apparent rejection, infection, or chronic inflammatory response. Fibrocartilaginous tissue with mature collagen fibers was observed predominantly in implants with seeded scaffolds compared to cell-free implants after 24 weeks. Similar results were not observed in the control group. Articular cartilage was preserved in the polymeric implants and showed higher chondrocyte cell number than the control group. These findings show that the PLDLA/PCL-T 90/10 scaffold has potential for orthopedic applications since this material allowed the formation of fibrocartilaginous tissue, a structure of crucial importance for repairing injuries to joints, including replacement of the meniscus and the protection of articular cartilage from degeneration. PMID:23593566

  11. Inhibition of tobramycin diffusion by binding to alginate.

    PubMed Central

    Nichols, W W; Dorrington, S M; Slack, M P; Walmsley, H L

    1988-01-01

    [3H]tobramycin bound to sodium alginate and to exopolysaccharide prepared from two mucoid strains of Pseudomonas aeruginosa. Binding to sodium alginate was similar to binding to exopolysaccharide, both in the dependence on tobramycin concentration and in the maximum binding observed at saturation. Incorporation of sodium alginate into agar plates reduced the zone sizes of growth inhibition caused by tobramycin. The reductions in zone sizes were quantitatively accounted for by the binding of tobramycin to sodium alginate during diffusion of the antibiotic away from the well in which it had been placed at the start of the experiment. However, the binding of tobramycin to the exopolysaccharide of P. aeruginosa, and the resulting inhibition of diffusion of the antibiotic, did not significantly increase the penetration time of a spherical microcolony with a radius of 125 micron, such as might be found in the respiratory tract of a patient with cystic fibrosis (from a 90% penetration time of 12 s in the absence of exopolysaccharide to one of 35 s with an exopolysaccharide concentration of 1.0% [wt/vol]). PMID:3132093

  12. Kefiran-alginate gel microspheres for oral delivery of ciprofloxacin.

    PubMed

    Blandón, Lina M; Islan, German A; Castro, Guillermo R; Noseda, Miguel D; Thomaz-Soccol, Vanete; Soccol, Carlos R

    2016-09-01

    Ciprofloxacin is a broad-spectrum antibiotic associated with gastric and intestinal side effects after extended oral administration. Alginate is a biopolymer commonly employed in gel synthesis by ionotropic gelation, but unstable in the presence of biological metal-chelating compounds and/or under dried conditions. Kefiran is a microbial biopolymer able to form gels with the advantage of displaying antimicrobial activity. In the present study, kefiran-alginate gel microspheres were developed to encapsulate ciprofloxacin for antimicrobial controlled release and enhanced bactericidal effect against common pathogens. Scanning electron microscopy (SEM) analysis of the hybrid gel microspheres showed a spherical structure with a smoother surface compared to alginate gel matrices. In vitro release of ciprofloxacin from kefiran-alginate microspheres was less than 3.0% and 5.0% at pH 1.2 (stomach), and 5.0% and 25.0% at pH 7.4 (intestine) in 3 and 21h, respectively. Fourier transform infrared spectroscopy (FTIR) of ciprofloxacin-kefiran showed the displacement of typical bands of ciprofloxacin and kefiran, suggesting a cooperative interaction by hydrogen bridges between both molecules. Additionally, the thermal analysis of ciprofloxacin-kefiran showed a protective effect of the biopolymer against ciprofloxacin degradation at high temperatures. Finally, antimicrobial assays of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhymurium, and Staphylococcus aureus demonstrated the synergic effect between ciprofloxacin and kefiran against the tested microorganisms.

  13. Structural Basis for Alginate Secretion Across the Bacterial Outer Membrane

    SciTech Connect

    J Whitney; I Hay; C Li; P Eckford; H Robinson; M Amaya; L Wood; D Ohman; C Bear; et al.

    2011-12-31

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  14. Inhibition of tobramycin diffusion by binding to alginate

    SciTech Connect

    Nichols, W.W.; Dorrington, S.M.; Slack, M.P.; Walmsley, H.L.

    1988-04-01

    (/sup 3/H)tobramycin bound to sodium alginate and to exopolysaccharide prepared from two mucoid strains of Pseudomonas aeruginosa. Binding to sodium alginate was similar to binding to exopolysaccharide, both in the dependence on tobramycin concentration and in the maximum binding observed at saturation. Incorporation of sodium alginate into agar plates reduced the zone sizes of growth inhibition caused by tobramycin. The reductions in zone sizes were quantitatively accounted for by the binding of tobramycin to sodium alginate during diffusion of the antibiotic away from the well in which it had been placed at the start of the experiment. However, the binding of tobramycin to the exopolysaccharide of P. aeruginosa, and the resulting inhibition of diffusion of the antibiotic, did not significantly increase the penetration time of a spherical microcolony with a radius of 125 micron, such as might be found in the respiratory tract of a patient with cystic fibrosis (from a 90% penetration time of 12 s in the absence of exopolysaccharide to one of 35 s with an exopolysaccharide concentration of 1.0% (wt/vol)).

  15. Structural basis for alginate secretion across the bacterial outer membrane

    SciTech Connect

    Whitney, J.C.; Robinson, H.; Hay, I. D.; Li, C.; Eckford, P. D. W.; Amaya, M. F.; Wood, L. F.; Ohman, D. E.; Bear, C. E.; Rehm, B. H.; Howell, P. L.

    2011-08-09

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  16. Serum albumin-alginate coated beads: mechanical properties and stability.

    PubMed

    Edwards-Lévy, F; Lévy, M C

    1999-11-01

    According to a previously described method, alginate beads were prepared from a Na-alginate solution containing propylene glycol alginate (PGA) and human serum albumin (HSA). The solution was added dropwise to a CaCl2 solution. The beads were treated with NaOH, which started the formation of amide bonds between HSA and PGA at the periphery, giving a membrane. Batches of beads with increasingly thick membranes were prepared using growing concentrations of NaOH, and studied with a texture analyser. When raising NaOH concentration, the rupture strength progressively increased, and the resistance strength to a deformation of 50% of total height also increased before slightly decreasing for the highest NaOH concentration. Variations of bead elasticity were also observed. When the beads were prepared with saline reducing gelation time from 10 to 5 min, and reaction time from 15 to 5 min, mechanical properties varied more progressively with the NaOH concentration, while the results became more reproducible. A series of assays conducted with 0.01 M NaOH confirmed the importance of using a short gelation time, and saline rather than water. Stability assays were also performed. The results were compared to those of alginate-polylysine coated beads and showed the interest of the transacylation method. PMID:10535819

  17. Alginate hydrogels coated with chitosan for wound dressing.

    PubMed

    Straccia, Maria Cristina; d'Ayala, Giovanna Gomez; Romano, Ida; Oliva, Adriana; Laurienzo, Paola

    2015-05-11

    In this work, a coating of chitosan onto alginate hydrogels was realized using the water-soluble hydrochloride form of chitosan (CH-Cl), with the dual purpose of imparting antibacterial activity and delaying the release of hydrophilic molecules from the alginate matrix. Alginate hydrogels with different calcium contents were prepared by the internal setting method and coated by immersion in a CH-Cl solution. Structural analysis by cryo-scanning electron microscopy was carried out to highlight morphological alterations due to the coating layer. Tests in vitro with human mesenchymal stromal cells (MSC) were assessed to check the absence of toxicity of CH-Cl. Swelling, stability in physiological solution and release characteristics using rhodamine B as the hydrophilic model drug were compared to those of relative uncoated hydrogels. Finally, antibacterial activity against Escherichia coli was tested. Results show that alginate hydrogels coated with chitosan hydrochloride described here can be proposed as a novel medicated dressing by associating intrinsic antimicrobial activity with improved sustained release characteristics.

  18. Bioinspired preparation of alginate nanoparticles using microbubble bursting.

    PubMed

    Elsayed, Mohamed; Huang, Jie; Edirisinghe, Mohan

    2015-01-01

    Nanoparticles are considered to be one of the most advanced tools for drug delivery applications. In this research, alginate (a model hydrophilic polymer) nanoparticles 80 to 200 nm in diameter were obtained using microbubble bursting. The natural process of bubble bursting occurs through a number of stages, which consequently produce nano- and microsized droplets via two main production mechanisms, bubble shell disintegration and a jetting process. In this study, nano-sized droplets/particles were obtained by promoting the disintegrating mechanism and suppressing (limiting) the formation of larger microparticles resulting from the jetting mechanism. A T-junction microfluidic device was used to prepare alginate microbubbles with different sizes in a well-controlled manner. The size of the bubbles was varied by controlling two processing parameters, the solution flow rate and the bubbling pressure. Crucially, the bubble size was found to be the determining factor for inducing (or limiting) the bubble shell disintegration mechanism and the size needed to promote this process was influenced by the properties of the solution used for preparing the bubbles, particularly the viscosity. The size of alginate nanoparticles produced via the disintegration mechanism was found to be directly proportional to the viscosity of the alginate solution.

  19. Fabrication of novel core-shell hybrid alginate hydrogel beads.

    PubMed

    Liu, Hongxia; Wang, Chaoyang; Gao, Quanxing; Liu, Xinxing; Tong, Zhen

    2008-03-01

    Novel hybrid alginate hydrogel beads with shells of porous CaCO3 microparticles were fabricated by templating water-in-oil emulsion and subsequent in situ gelation. Porous CaCO3 microparticles were self-assembled at interfaces of water-in-oil emulsion. Water droplets containing alginate in the emulsion were subsequently in situ gelated by Ca2+ released from CaCO3 through decreasing pH with slow hydrolysis of d-glucono-delta-lactone (GDL). The resulting hybrid beads with alginate gel cores and shells of porous CaCO3 microparticles were called colloidosomes. The packed density of CaCO3 microparticles in the shell increased with increasing the ratio of the CaCO3 microparticle weight to the water phase volume Mp/Vw and decreased with addition of NaCl into water. The size of the produced colloidosome beads was independent of Mp/Vw. Increasing the volume fraction of water Phi w to 0.5, some colloidosome beads deformed to nonspheral shape and even broken. Brilliant blue (BB) as a drug model was loaded into the colloidosome beads by being dissolved in the alginate aqueous solution before gelation. The BB release from the colloidosome beads was slowed down because of the formation of the shells of CaCO3 microparticles. The colloidosome beads may find applications as delivery vehicles for drugs, cosmetics, food supplements and living cell.

  20. Alginate Hydrogels Coated with Chitosan for Wound Dressing

    PubMed Central

    Straccia, Maria Cristina; Gomez d’Ayala, Giovanna; Romano, Ida; Oliva, Adriana; Laurienzo, Paola

    2015-01-01

    In this work, a coating of chitosan onto alginate hydrogels was realized using the water-soluble hydrochloride form of chitosan (CH-Cl), with the dual purpose of imparting antibacterial activity and delaying the release of hydrophilic molecules from the alginate matrix. Alginate hydrogels with different calcium contents were prepared by the internal setting method and coated by immersion in a CH-Cl solution. Structural analysis by cryo-scanning electron microscopy was carried out to highlight morphological alterations due to the coating layer. Tests in vitro with human mesenchymal stromal cells (MSC) were assessed to check the absence of toxicity of CH-Cl. Swelling, stability in physiological solution and release characteristics using rhodamine B as the hydrophilic model drug were compared to those of relative uncoated hydrogels. Finally, antibacterial activity against Escherichia coli was tested. Results show that alginate hydrogels coated with chitosan hydrochloride described here can be proposed as a novel medicated dressing by associating intrinsic antimicrobial activity with improved sustained release characteristics. PMID:25969981

  1. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Propylene glycol alginate. 172.858 Section 172.858 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... do not preclude such use: (1) As a stabilizer in frozen dairy desserts, in fruit and water ices,...

  2. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol alginate. 172.858 Section 172.858 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... use: (1) As a stabilizer in frozen dairy desserts, in fruit and water ices, and in confections...

  3. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Propylene glycol alginate. 172.858 Section 172.858 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... do not preclude such use: (1) As a stabilizer in frozen dairy desserts, in fruit and water ices,...

  4. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Propylene glycol alginate. 172.858 Section 172.858 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... do not preclude such use: (1) As a stabilizer in frozen dairy desserts, in fruit and water ices,...

  5. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Propylene glycol alginate. 172.858 Section 172.858 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... do not preclude such use: (1) As a stabilizer in frozen dairy desserts, in fruit and water ices,...

  6. Green synthesis and characterization of alginate nanoparticles and its role as a biosorbent for Cr(VI) ions

    NASA Astrophysics Data System (ADS)

    Geetha, P.; Latha, M. S.; Pillai, Saumya S.; Deepa, B.; Santhosh Kumar, K.; Koshy, Mathew

    2016-02-01

    Green synthesis of nanoparticles has attained considerable attention in recent years because of its myriad of applications including drug delivery, tissue engineering and water purification. In the present study, alginate nanoparticles stabilized by honey were prepared by cross-linking aqueous solution of alginate with calcium ions. Honey mediated synthesis has been reported earlier for the production of metal nanoparticles. However no literature is available on the use of this technique for polymeric nanoparticles. Highly stable nanoparticles of 10-100 nm size were generated by this technique. The synthesised nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopic techniques. Potential of using these nanoparticles for heavy metal removal was studied by using Cr(VI) from aqueous solution, where a maximum removal efficiency of 93.5% was obtained. This method was also successfully employed for the production of other polymeric nanoparticles like casein, chitosan and albumin.

  7. A design protocol for tailoring ice-templated scaffold structure

    PubMed Central

    Pawelec, K. M.; Husmann, A.; Best, S. M.; Cameron, R. E.

    2014-01-01

    In this paper, we show, for the first time, the key link between scaffold architecture and latent heat evolution during the production of porous biomedical collagen structures using freeze-drying. Collagen scaffolds are used widely in the biomedical industry for the repair and reconstruction of skeletal tissues and organs. Freeze-drying of collagen slurries is a standard industrial process, and, until now, the literature has sought to characterize the influence of set processing parameters including the freezing protocol and weight percentage of collagen. However, we are able to demonstrate, by monitoring the local thermal events within the slurry during solidification, that nucleation, growth and annealing processes can be controlled, and therefore we are able to control the resulting scaffold architecture. Based on our correlation of thermal profile measurements with scaffold architecture, we hypothesize that there is a link between the fundamental freezing of ice and the structure of scaffolds, which suggests that this concept is applicable not only for collagen but also for ceramics and pharmaceuticals. We present a design protocol of strategies for tailoring the ice-templated scaffold structure. PMID:24402916

  8. A design protocol for tailoring ice-templated scaffold structure.

    PubMed

    Pawelec, K M; Husmann, A; Best, S M; Cameron, R E

    2014-03-01

    In this paper, we show, for the first time, the key link between scaffold architecture and latent heat evolution during the production of porous biomedical collagen structures using freeze-drying. Collagen scaffolds are used widely in the biomedical industry for the repair and reconstruction of skeletal tissues and organs. Freeze-drying of collagen slurries is a standard industrial process, and, until now, the literature has sought to characterize the influence of set processing parameters including the freezing protocol and weight percentage of collagen. However, we are able to demonstrate, by monitoring the local thermal events within the slurry during solidification, that nucleation, growth and annealing processes can be controlled, and therefore we are able to control the resulting scaffold architecture. Based on our correlation of thermal profile measurements with scaffold architecture, we hypothesize that there is a link between the fundamental freezing of ice and the structure of scaffolds, which suggests that this concept is applicable not only for collagen but also for ceramics and pharmaceuticals. We present a design protocol of strategies for tailoring the ice-templated scaffold structure.

  9. Plant-Derived Human Collagen Scaffolds for Skin Tissue Engineering

    PubMed Central

    Willard, James J.; Drexler, Jason W.; Das, Amitava; Roy, Sashwati; Shilo, Shani; Shoseyov, Oded

    2013-01-01

    Tissue engineering scaffolds are commonly formed using proteins extracted from animal tissues, such as bo