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Sample records for poly l-lactic acid

  1. Protein adsorption on piezoelectric poly(L-lactic) acid thin films by scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Barroca, Nathalie; Vilarinho, Paula M.; Daniel-da-Silva, Ana Luisa; Wu, Aiying; Fernandes, Maria Helena; Gruverman, Alexei

    2011-03-01

    Up until now, no direct evidence of protein adsorption processes associated with polar activity of a piezoelectric has been reported. This work presents the experimental evidence of the protein adsorption process' dependence on the surface polarization of a piezoelectric by showing at the local scale that the process of protein adsorption is highly favored in the poled areas of a piezoelectric polymer such as poly(L-lactic) acid.

  2. Poly(L-lactic acid)-modified silica stationary phase for reversed-phase and hydrophilic interaction liquid chromatography.

    PubMed

    Ohyama, Kaname; Takasago, Shizuka; Kishikawa, Naoya; Kuroda, Naotaka

    2015-03-01

    Poly(L-lactic acid) is a linear aliphatic thermoplastic polyester that can be produced from renewable resources. A poly(L-lactic acid)-modified silica stationary phase was newly prepared by amide bond reaction between amino groups on aminopropyl silica and carboxylic acid groups at the end of the poly(L-lactic acid) chain. The poly(L-lactic acid)-silica column was characterized in reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography with the use of different mobile phase compositions. The poly(L-lactic acid)-silica column was found to work in both modes, and the retention of test compounds depending on acetonitrile content exhibited "U-shaped" curves, which was an indicator of reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography mixed-mode retention behavior. In addition, carbonyl groups included into the poly(L-lactic acid) backbone work as an electron-accepting group toward a polycyclic aromatic hydrocarbon and provide π-π interactions. PMID:25546473

  3. Collagen Stimulators: Poly-L-Lactic Acid and Calcium Hydroxyl Apatite.

    PubMed

    Breithaupt, Andrew; Fitzgerald, Rebecca

    2015-11-01

    Over the last decade, many studies of the structural changes observed in the aging face (in bone, fat pads, facial ligaments, muscle, skin) have increased our understanding that facial rejuvenation is more complex and nuanced than simply filling lines and folds or cutting and lifting soft tissue and skin. This, in addition to the many new products introduced to the marketplace over the same period, has fueled the evolution of panfacial rejuvenation and restoration using fillers. This article discusses current techniques used with calcium hydroxylapatite and poly-l-lactic acid to safely and effectively address changes observed in the aging face. PMID:26505542

  4. Nanoscale patterning of poly (L-lactic acid) films with nanoimprinting methods

    NASA Astrophysics Data System (ADS)

    Peer, Akshit; Dhakal, Rabin; Biswas, Rana; Kim, Jaeyoun

    2015-08-01

    Biological applications can benefit from nanoscale texturing of materials for biomedical functions. Texturing of biomaterials can increase the available surface area so that they can be coated with larger doses of therapeutic agents. We demonstrate nano-texturing of poly (L-lactic acid) (PLLA) - a prototypical material commonly used for drug-eluting coronary stents and as a template for cell growth. A master pattern consisting of a periodic array was transferred to a PDMS mold. Drop-casting PLLA achieves the best transfer of patterns, with nanoarrays of holes with pitch ~700 nm. Nanoimprinting the PLLA films results in shallower and less resolved features.

  5. Biomimetic poly(glycerol sebacate)/poly(l-lactic acid) blend scaffolds for adipose tissue engineering.

    PubMed

    Frydrych, Martin; Román, Sabiniano; MacNeil, Sheila; Chen, Biqiong

    2015-05-01

    Large three-dimensional poly(glycerol sebacate) (PGS)/poly(l-lactic acid) (PLLA) scaffolds with similar bulk mechanical properties to native low and high stress adapted adipose tissue were fabricated via a freeze-drying and a subsequent curing process. PGS/PLLA scaffolds containing 73vol.% PGS were prepared using two different organic solvents, resulting in highly interconnected open-pore structures with porosities and pore sizes in the range of 91-92% and 109-141μm, respectively. Scanning electron microscopic analysis indicated that the scaffolds featured different microstructure characteristics, depending on the organic solvent in use. The PGS/PLLA scaffolds had a tensile Young's modulus of 0.030MPa, tensile strength of 0.007MPa, elongation at the maximum stress of 25% and full shape recovery capability upon release of the compressive load. In vitro degradation tests presented mass losses of 11-16% and 54-55% without and with the presence of lipase enzyme in 31days, respectively. In vitro cell tests exhibited clear evidence that the PGS/PLLA scaffolds prepared with 1,4-dioxane as the solvent are suitable for culture of adipose derived stem cells. Compared to pristine PLLA scaffolds prepared with the same procedure, these scaffolds provided favourable porous microstructures, good hydrophilic characteristics, and appropriate mechanical properties for soft tissue applications, as well as enhanced scaffold cell penetration and tissue in-growth characteristics. This work demonstrates that the PGS/PLLA scaffolds have potential for applications in adipose tissue engineering. PMID:25769230

  6. Novel superhydrophilic poly(l-lactic acid-co-ε-caprolactone)/fibrinogen electrospun patch for rat abdominal wall reconstruction.

    PubMed

    Liu, Zhang; Li, Shaojie; Su, Ling; Sun, Kang; Wu, Xujun; Wu, Feng; Huang, Weihong; Yang, Li; Tang, Jianxiong; He, Hongbing

    2015-08-01

    A novel superhydrophilic hybrid scaffold was created by electrospinning a mixture of poly(l-lactic acid-co-ε-caprolactone) and formulated fibrinogen. The hybrid scaffolds possess the combined benefits of each individual component, such as moderate mechanical strength and excellent biocompatibility. In vitro studies also revealed that endothelial cells seeded on the hybrid scaffolds achieved a relatively high level of cell attachment after three days of culture and a significant increase in the proliferation rate after seven days of culture, compared with pure fibrinogen or poly(l-lactic acid-co-ε-caprolactone) scaffolds. A comparative study of hybrid and pure poly(l-lactic acid-co-ε-caprolactone) patches was performed in an abdominal wall defect model in rats. In both groups, implants degraded by six months, but muscle reconstruction was only observed in the hybrid patch group. PMID:25791683

  7. Mechanism of drug release from poly(L-lactic acid) matrix containing acidic or neutral drugs.

    PubMed

    Miyajima, M; Koshika, A; Okada, J; Ikeda, M

    1999-08-01

    The release profiles of acidic and neutral drugs from poly(L-lactic acid) [P(L)LA] matrices were investigated to reveal their release mechanism. Cylindrical matrices (rods; 10 mmx1 mm diameter) were prepared by the heat compression method. The acidic and neutral drugs investigated were dissolved in the P(L)LA rods. It was found that the release profiles consisted of two sequential stages. At the first release stage, P(L)LA remained in an amorphous state and the drugs diffused through the hydrated matrices. At the second release stage, P(L)LA transformed to a semicrystalline state and the drugs diffused through water-filled micropores developed by polymer crystallization. In addition, the drugs were also found to precipitate out as crystals in the rods, resulting in a transformation of the rods into drug-dispersed matrices. On the basis of these findings, we derived a modified diffusion equation for the drug release at the second stage. This equation showed good fits to the release profiles of these drugs. Furthermore, the availability of the derived equation was supported by the acceleration in the fractional drug release rate noted both with decreases in the drug content in the rod and increases in the pH of the medium. PMID:10425326

  8. Micro/nanofabrication of poly(L-lactic acid) using focused ion beam direct etching

    NASA Astrophysics Data System (ADS)

    Oyama, Tomoko Gowa; Hinata, Toru; Nagasawa, Naotsugu; Oshima, Akihiro; Washio, Masakazu; Tagawa, Seiichi; Taguchi, Mitsumasa

    2013-10-01

    Micro/nanofabrication of biocompatible and biodegradable poly(L-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  9. Surface modification on polydimethylsiloxane-based microchannels with fragmented poly(l-lactic acid) nanosheets.

    PubMed

    Yang, Lu; Okamura, Yosuke; Kimura, Hiroshi

    2015-11-01

    Surface modification is a critical issue in various applications of polydimethylsiloxane (PDMS)-based microfluidic devices. Here, we describe a novel method through which PDMS-based microchannels were successfully modified with fragmented poly(l-lactic acid) (PLLA) nanosheets through a simple patchwork technique that exploited the high level of adhesiveness of PLLA nanosheets. Compared with other surface modification methods, our method required neither complicated chemical modifications nor the use of organic solvents that tend to cause PDMS swelling. The experimental results indicated that the modified PDMS exhibited excellent capacity for preventing the adhesion and activation of platelets. This simple yet efficient method can be used to fabricate the special PDMS microfluidic devices for biological, medical, and even hematological purposes. PMID:26634016

  10. Satisfying patient expectations with poly-L-lactic acid soft tissue augmentation.

    PubMed

    Vleggaar, Danny; Fitzgerald, Rebecca; Lorenc, Z Paul

    2014-04-01

    Patient interest and physician use of soft tissue augmentation have increased significantly in recent years, especially among younger patients. A recent consumer survey conducted on behalf of the American Society of Plastic Surgeons found that the majority of respondents would rather have a facial injectable treatment than a surgical treatment. In another recent survey, consumers gave the highest overall satisfaction ratings to injectable filler treatments (92%), including poly-L-lactic acid (PLLA), and injectable wrinkle relaxers (92%), with injectable fillers receiving the highest "extremely satisfied" rating (45%). Long-lasting benefit is a desirable attribute in soft tissue augmentation, making PLLA a favorable alternative for many patients. When considering the use of PLLA, clinicians should ensure that their patients understand its benefit profile, and that these benefits are consistent with the patients' cosmetic goals. The implementation of the latest recommendations on methodological approaches in the use of PLLA will minimize the occurrence of adverse events, further enhancing patient satisfaction. PMID:24719077

  11. Composition and mechanism of action of poly-L-lactic acid in soft tissue augmentation.

    PubMed

    Vleggaar, Danny; Fitzgerald, Rebecca; Lorenc, Z Paul

    2014-04-01

    Poly-L-lactic acid (PLLA) is a synthetic, biocompatible, biodegradable polymer. For its use in soft tissue augmentation, it is supplied as a lyophilized powder containing PLLA microparticles, the size and chemical attributes of which are tightly controlled. As a biocompatible material, PLLA generates a desired subclinical inflammatory tissue response that leads to encapsulation of the microparticles, stimulation of host collagen production, and fibroplasia. Over time, the PLLA degrades, the inflammatory response wanes, and host collagen production increases. This response leads to the generation of new volume and structural support that occurs in a gradual, progressive manner, and which can last for years. Coupled with consistent, optimized injection methodology, the use of PLLA in soft tissue augmentation can result in a predictable cosmetic effect that is completely controlled by the treating clinician. PMID:24719074

  12. Novel biocompatible and biodegradable ultrathin films of poly (L-Lactic acid) by plasma polymerization

    NASA Astrophysics Data System (ADS)

    Chang, Yi-Hsin; Chang, Chun-Chih; Chen, Ying-Chu; Yang, A. C.-M.; Liu, Y. C.

    2006-03-01

    Ultra-thin films (<= 50 nm) of biodegradable poly (L-lactic acid) were prepared through efficient RF plasma synthesis. The surface morphology of deposited films was amorphous and molecularly uniform (Ra = 0.7 nm). The chemical compositions as determined from FTIR and NMR demonstrated extraordinarily high retention of ester groups with a small fraction of chain cross-linking that could be controlled by process parameters. The chemical routes of the polymerization were described and discussed. This versatile thin film coating technique is very useful for surface engineering of general biomedical devices and implants for improved biocompatibility. In addition, PLLA polymerized in the liquid phase by plasma was also explored and will be presented. This work is supported by National Science Council of Taiwan.

  13. Controlled protein release from polyethyleneimine-coated poly(L-lactic acid)/pluronic blend matrices.

    PubMed

    Park, T G; Cohen, S; Langer, R

    1992-01-01

    Protein release from degradable polymer matrices, composed of poly(L-lactic acid) and its blends with Pluronic surfactant, was investigated with and without the aqueous coating of an adsorptive water-soluble polymer, polyethyleneimine (PEI). PEI is a highly branched cationic polymer containing primary, secondary, and tertiary amino groups in its backbone. The treatment of PEI for PLA/Pluronic blend films exhibited a remarkable decrease in the "burst" release of protein at an initial stage and a significant extension in the protein release period. Protein release profiles could be controlled by varying PEI treatment time and its concentration. Our results suggest that PEI diffuses into the polymer matrices and crosslinks protein molecules by ionic interactions. Such a PEI-protein network near the surface region of matrix may act as a diffusional barrier for further release of protein molecules. PMID:1589407

  14. Adolescent Femoral Chondral Fragment Fixation With Poly-L-Lactic Acid Chondral Darts.

    PubMed

    Morris, John K; Weber, Alexander E; Morris, Mark S

    2016-01-01

    Large chondral injuries without attached bone are uncommon. This report describes a 14-year-old boy who had a unique stress reaction between the bone and the overlying cartilage, predominantly of the anterior lateral femoral condyle, during a week-long basketball camp, resulting in complete displacement of a 2.5 × 2.5-cm full-thickness articular cartilage lesion. There was a 6-day interval from the time of the injury to the first office appointment. Scheduling of magnetic resonance imaging and insurance approval took another week, and then surgery scheduling, including insurance approval and arranging for surgical supplies, took another week. Three weeks after the initial injury, the patient underwent diagnostic arthroscopy and open arthrotomy, and the cartilage-free fragment was returned to the donor site and fixed with poly-L-lactic acid chondral darts. Considerable delamination of the shoulders of the defect was noted on preoperative magnetic resonance imaging and at the time of surgery, suggesting an unusual prodromal stress reaction. Although there was no underlying subchondral bone on the free cartilage fragment, the injury healed. The patient had return of full knee range of motion and strength. Magnetic resonance imaging performed 3 months postoperatively showed healed cartilage. At 1 year of clinical follow-up, the patient had no clinical sequelae from the initial injury and had returned to competitive basketball. Prompt recognition of this injury pattern and subsequent surgical repair are necessary because the window of opportunity closes as fibrous healing occurs and the cartilage fragment deforms. The poly-L-lactic acid chondral dart system was instrumental to the success of this case. PMID:26840696

  15. Biocatalyzed approach for the surface functionalization of poly(L-lactic acid) films using hydrolytic enzymes.

    PubMed

    Pellis, Alessandro; Acero, Enrique Herrero; Weber, Hansjoerg; Obersriebnig, Michael; Breinbauer, Rolf; Srebotnik, Ewald; Guebitz, Georg M

    2015-09-01

    Poly(lactic acid) as a biodegradable thermoplastic polyester has received increasing attention. This renewable polyester has found applications in a wide range of products such as food packaging, textiles and biomedical devices. Its major drawbacks are poor toughness, slow degradation rate and lack of reactive side-chain groups. An enzymatic process for the grafting of carboxylic acids onto the surface of poly(L-lactic acid) (PLLA) films was developed using Candida antarctica lipase B as a catalyst. Enzymatic hydrolysis of the PLLA film using Humicola insolens cutinase in order to increase the number of hydroxyl and carboxylic groups on the outer polymer chains for grafting was also assessed and showed a change of water contact angle from 74.6 to 33.1° while the roughness and waviness were an order of magnitude higher in comparison to the blank. Surface functionalization was demonstrated using two different techniques, (14) C-radiochemical analysis and X-ray photoelectron spectroscopy (XPS) using (14) C-butyric acid sodium salt and 4,4,4-trifluorobutyric acid as model molecules, respectively. XPS analysis showed that 4,4,4-trifluorobutyric acid was enzymatically coupled based on an increase of the fluor content from 0.19 to 0.40%. The presented (14) C-radiochemical analyses are consistent with the XPS data indicating the potential of enzymatic functionalization in different reaction conditions. PMID:25963883

  16. Pressure-Sensitive Touch Panel Based on Piezoelectric Poly(L-lactic acid) Film

    NASA Astrophysics Data System (ADS)

    Ando, Masamichi; Kawamura, Hideki; Kitada, Hiroaki; Sekimoto, Yasuyuki; Inoue, Takafumi; Tajitsu, Yoshiro

    2013-09-01

    Poly(lactic acid) (PLA) is a widely used biomass-derived polymer. It is chiral because the lactic acid monomer has an asymmetric carbon. If the L-lactide is polymerized, then the PLA polymer is an L-type PLA or poly(L-lactic acid) (PLLA); if the D-lactide in PLA is polymerized, then the polymer is a D-type PLA (PDLA). When these polymers undergo drawing or elongation, they exhibit shear piezoelectricity. PLA films are highly transparent and do not exhibit pyroelectricity because of the lack of intrinsic polarization. Therefore, if a PLLA film is used for a touch panel, which is operated by pressure, there is no spurious signal due to heating from the fingers. This suggests that PLLA films may be suitable for touch panels using pressure detection. We used PLLA as the base film of a projected capacitive touch panel with multiple electrodes, and demonstrated a multitouch gesture screen that was sensitive to pressure applied on the screen. This touch panel technology has potential applications for smart phones and tablet personal computers.

  17. Simple surface coating of electrospun poly-L-lactic acid scaffolds to induce angiogenesis.

    PubMed

    Gigliobianco, Giulia; Chong, Chuh K; MacNeil, Sheila

    2015-07-01

    Tissue-engineered constructs often fail due to poor integration with the patient's tissues. Specifically, they fail to be neovascularised, leading to the death and loss of the implanted tissues. Thus, there is a need to produce angiogenic materials to improve tissue integration. We describe the development of a layer-by-layer approach to coat electrospun scaffolds to help promote angiogenesis into these biomaterials once implanted. Electrospun poly-L-lactic acid was coated comparing two different techniques - one using alternative layers of polyethyleneImine (PEI) and polyacrylic Acid (PAC) and one with alternative layers of PEI and heparin for a total of seven layers in both cases. Both scaffolds were then coated with heparin as the final layer. The scaffold coated with alternate PEI and PAC showed a clear ability to bind the most heparin. This scaffold was then studied further for its ability to bind vascular endothelial growth factor, which was confirmed using an ELISA. The scaffold coated with seven alternate layers of PEI and PAC and heparin was then implanted in a chick chorionic allantoic membrane (CAM) assay. After a period of 7 days in the CAM, the coated scaffold showed strong angiogenic activity. In contrast, the uncoated scaffolds did not promote angiogenesis. We conclude that this approach to functionalising scaffolds is effective within a clinically relevant time period (7 days in an in-vivo angiogenic model) and suggest this will be useful for improving integration of scaffolds once implanted. PMID:25652887

  18. Poly(D,L-lactic acid)-glycerol-based nanoparticles for curcumin delivery.

    PubMed

    Yoon, In-Soo; Park, Ju-Hwan; Kang, Hyo Jin; Choe, Ji Hyeong; Goh, Min Su; Kim, Dae-Duk; Cho, Hyun-Jong

    2015-07-01

    Poly(D,L-lactic acid)-glycerol (PDLLA-G)-based nanoparticles (NPs) were fabricated for the intravenous delivery of curcumin (CUR). NPs with a mean diameter of approximately 200 nm, a narrow size distribution, and capable of efficient drug encapsulation were prepared using an emulsification-solvent evaporation method. The stability of NPs was verified in water, phosphate buffered saline (PBS), and serum after 24-h incubation. A sustained drug release pattern was observed, and the amount of CUR released in acidic media (pH 5.5) was higher than in media at physiological pH (pH 7.4). Blank NPs (without drug loading) did not exhibit severe cytotoxicity in MDA-MB-231 human breast adenocarcinoma cells. The in vitro anti-tumor efficacy of CUR-loaded NPs in MDA-MB-231 cells was comparable to that of a solution of CUR. Pharmacokinetic studies in rats showed that the in vivo clearance (CL) of CUR in the NP-treated group was lower than the group treated with CUR solution. Therefore, encapsulation of CUR in PDLLA-G NPs was shown to enable prolonged circulation of the drug in the blood stream and guarantee improved anticancer activity after intravenous injection. These biocompatible NPs could be an efficient nano-sized injectable formulation for CUR delivery. PMID:25900098

  19. A poly(L-lactic acid) nanofibre mesh scaffold for endothelial cells on vascular prostheses.

    PubMed

    François, Sébastien; Chakfé, Nabil; Durand, Bernard; Laroche, Gaétan

    2009-09-01

    The absence of neoendothelium covering the intimal surface of small-diameter PET vascular prostheses is known to be one cause of failure following implantation in humans. Protein coatings currently used to seal porous textile structures have not shown evidence of in vivo neoendothelium formation. In this study, we covered the inner wall of textile prostheses with a biodegradable synthetic scaffold made of poly(l-lactic) acid (PLLA) nanofibres obtained by an air-spinning process we developed that produces nanofibres by stretching a solution of polymer with a high-speed compressed air jet. The air spinning was designed to process a scaffold that would support good endothelial cell proliferation. Our innovative process enabled us to very rapidly cover textile samples with PLLA nanofibres to determine the influence of air pressure, polymer solution flow rate and polymer concentration on fibre quality. High air pressure was shown to induce a significant number of ruptures. High polymer flow rate stimulated the formation of polymer droplets, and the fibre diameter mean increased for the 4% and 7% polymer concentrations. The adherence and proliferation of bovine aortic endothelial cells was assessed to compare prosthesis samples with or without the PLLA nanofibre scaffold and PET film. The PLLA nanofibres displayed a significantly better proliferation rate, and enabled endothelial cells to proliferate in the monolayer. Our novel approach therefore opens the door to the development of partially degradable textile prostheses with a blood/textile interface that supports endothelial cell proliferation. PMID:19345622

  20. Treatment of the aged hand with injectable poly-l-lactic acid.

    PubMed

    Rendon, Marta I; Cardona, Lina M; Pinzon-Plazas, Mariana

    2010-12-01

    We report the use of injectable poly-l-lactic acid (PLLA) for volume restoration in a 45-year-old white female who was concerned about the appearance of her hands. The patient expressed a desire for long-term restoration, and selected injectable PLLA because of its known 2-year duration of effect, although she was informed that injectable PLLA is not FDA-approved for use in the hands. After reconstitution with 8 ml of diluent plus lidocaine, 0.1-0.2-ml aliquots of injectable PLLA were injected into selected sites, up to 5 ml per hand. The patient underwent three identical treatments, followed by postinjection use of moisturizing cream and massage; improvement in appearance was noted by the patient between the second and third treatments. Correction was maintained for at least 18 months, with no adverse events. We have also briefly reviewed the literature on the use of injectable PLLA for volume restoration in the hand. PMID:21142738

  1. European expert recommendations on the use of injectable poly-L-lactic acid for facial rejuvenation.

    PubMed

    Alessio, Redaelli; Rzany, Berthold; Eve, Linda; Grangier, Yann; Herranz, Pedro; Olivier-Masveyraud, Frédérique; Vleggaar, Danny

    2014-09-01

    Over the last few years, there have been a number of important changes in how we appreciate and understand the aging face. Volume loss is now recognized as a major component of facial aging. Treatment options that replace lost volume are increasingly used for recontouring and rejuvenation of the aging face. In this review we present and discuss the European Expert Group recommendations on the ideal use of the unique collagen stimulator, poly-L-lactic acid (PLLA, Sculptra®, Sinclair Pharmaceuticals) for facial rejuvenation lasting up to 25 months. Optimal results are achieved based on a detailed knowledge of facial anatomy, correct treatment procedure, specifically the right dilution, the correct injection technique, as well as appropriate patient aftercare. PLLA is an effective and safe collagen stimulator that treats the whole face. PLLA is simple to use, provides the foundation for facial rejuvenation, is easy to combine with other treatments, and gives long-lasting effects with a high level of patient satisfaction. PMID:25226006

  2. Biomimetic hydroxyapatite coating on pore walls improves osteointegration of poly(L-lactic acid) scaffolds.

    PubMed

    Deplaine, H; Lebourg, M; Ripalda, P; Vidaurre, A; Sanz-Ramos, P; Mora, G; Prósper, F; Ochoa, I; Doblaré, M; Gómez Ribelles, J L; Izal-Azcárate, I; Gallego Ferrer, G

    2013-01-01

    Polymer-ceramic composites obtained as the result of a mineralization process hold great promise for the future of tissue engineering. Simulated body fluids (SBFs) are widely used for the mineralization of polymer scaffolds. In this work an exhaustive study with the aim of optimizing the mineralization process on a poly(L-lactic acid) (PLLA) macroporous scaffold has been performed. We observed that when an air plasma treatment is applied to the PLLA scaffold its hydroxyapatite nucleation ability is considerably improved. However, plasma treatment only allows apatite deposition on the surface of the scaffold but not in its interior. When a 5 wt % of synthetic hydroxyapatite (HAp) nanoparticles is mixed with PLLA a more abundant biomimetic hydroxyapatite layer grows inside the scaffold in SBF. The morphology, amount, and composition of the generated biomimetic hydroxyapatite layer on the pores' surface have been analyzed. Large mineralization times are harmful to pure PLLA as it rapidly degrades and its elastic compression modulus significantly decreases. Degradation is retarded in the composite scaffolds because of the faster and extensive biomimetic apatite deposition and the role of HAp to control the pH. Mineralized scaffolds, covered by an apatite layer in SBF, were implanted in osteochondral lesions performed in the medial femoral condyle of healthy sheep. We observed that the presence of biomimetic hydroxyapatite on the pore's surface of the composite scaffold produces a better integration in the subchondral bone, in comparison to bare PLLA scaffolds. PMID:23152082

  3. Transfer molding processes for nanoscale patterning of poly-L-lactic acid (PLLA) films

    NASA Astrophysics Data System (ADS)

    Dhakal, Rabin; Peer, Akshit; Biswas, Rana; Kim, Jaeyoun

    2016-03-01

    Nanoscale patterned structures composed of biomaterials exhibit great potential for the fabrication of functional biostructures. In this paper, we report cost-effective, rapid, and highly reproducible soft lithographic transfer-molding techniques for creating periodic micro- and nano-scale textures on poly (L-lactic acid) (PLLA) surface. These artificial textures can increase the overall surface area and change the release dynamics of the therapeutic agents coated on it. Specifically, we use the double replication technique in which the master pattern is first transferred to the PDMS mold and the pattern on PDMS is then transferred to the PLLA films through drop-casting as well as nano-imprinting. The ensuing comparison studies reveal that the drop-cast PLLA allows pattern transfer at higher levels of fidelity, enabling the realization of nano-hole and nano-cone arrays with pitch down to ~700 nm. The nano-patterned PLLA film was then coated with rapamycin to make it drug-eluting.

  4. Fibroblast response is enhanced by poly(L-lactic acid) nanotopography edge density and proximity

    PubMed Central

    Milner, Keith R; Siedlecki, Christopher A

    2007-01-01

    The development of scaffolds for use in tissue engineering applications requires careful choice of macroscale properties, such as mechanical characteristics, porosity and biodegradation. The micro- and nano-scale properties of the scaffold surface are also an important design criterion as these influence cell adhesion, proliferation, and differentiation. The cellular response is known to be affected by surface topography but the mechanisms governing this remain unclear. Homogenous poly(L-lactic acid) was textured with surface nanotopographies by two-stage replication molding of heterogeneous demixed polymer films. Initial cell adhesion was improved on nanotextured surfaces compared with smooth controls, but subsequent cell density was significantly reduced on the roughest surfaces. Improvements in cell response were found to correlate with focal contact and actin microfilament development. Cell response was found to trend both with the surface density of topography edges and with inter-topography spacing, indicating possible roles for edges stimulating cell adhesion/proliferation or for spacing to modulate the ability of integrin-ligand bonds to cluster and form focal adhesions. This study furthers understanding of the geometric properties of surface nanotopographies that affect cellular response. It is hoped that identification of the mechanisms governing cell-topography interactions will allow rule-based design of biomaterial surface to engineer specific cellular responses. PMID:17722548

  5. Release of FITC-BSA from poly(l-lactic acid) microspheres analysis using flow cytometry.

    PubMed

    Kuo, Chih-Feng; Tsao, Nina; Chou, Hsin-Hao; Liu, Yi-Ling; Hsieh, Wen-Chuan

    2012-01-01

    In this investigation, biodegradable polymer poly(L-lactic acid) (PLA) microspheres were prepared by the W(1)/O/W(2) solvent evaporation method. The inner phase was aqueous solution (W(1)) that contained bovine serum albumin that was labeled with fluorescein isothiocyanate (FITC-BSA). PLA was dissolved in chloroform with emulsifier sorbitan monooleate (span 80) as the dispersed phase (O). These two solutions (W(1)/O) were emulsified by a homogenizer to form a primary emulsion. Polyvinyl alcohol (PVA) used as surfactant, was applied in the formation of microspheres (W(2)). 0.5% (w/v) PLA was stirred at 3000 rpm using a homogenizer. Microspheres with sizes of up to around 10 μm were produced. These microspheres were separated by the glycerol gradient method, and take microspheres at part of 25% glycerol gradient concentration was analyzed by flow cytometry, indicating a more homogeneous particle size distribution than that not separated. The microspheres were degraded using several enzymes, and around 40% was degraded by 72 h. This result reveals the effectiveness of drug delivery by PLA microspheres, which was evaluated by performing a drug release test and flow cytometric analysis. The FITC-BSA concentration in the supernatant increased with the experimental time. At the phagocytosis experiments, encapsulated with FITC-BSA drug of microspheres can be used by the cell, as particle size approximately 1 μm. PMID:21992796

  6. Poly(L-lactic acid) membranes: absence of genotoxic hazard and potential for drug delivery.

    PubMed

    Uzun, Nelson; Martins, Thomás Duzzi; Teixeira, Gabriella Machado; Cunha, Nayanne Larissa; Oliveira, Rogério Belle; Nassar, Eduardo José; Dos Santos, Raquel Alves

    2015-01-22

    The use of poly(L-lactic acid) (PLA) has been considered an important alternative for medical devices once this polyester presents biomechanical, optical and biodegradable properties. Moreover, the use of PLA results in less inflammatory reactions and more recently it has been proposed its application in drug delivery systems. Genotoxicological evaluations are considered part of the battery assays in toxicological analysis. Considering the wide applications of PLA, the present work evaluated the potential cytotoxic and genotoxic effects of PLA in CHO-K1 cells, as well as its physicochemical properties. No cytotoxic effects of PLA were detected by colorimetric tetrazolium assay (XTT) analysis, and the clonogenic survival assay showed that PLA did not disrupt the replicative cell homeostasis, neither exhibited genotoxic effects as evidenced by comet and micronucleus assays. Thermogravimetric properties of PLA were not altered after contact with cells and this film exhibited ability in absorb and release Europium(III) complex. All these data suggest genotoxicological safety of PLA for further applications in drug delivery systems. PMID:25479058

  7. Superhydrophobic poly(L-lactic acid) surface as potential bacterial colonization substrate

    PubMed Central

    2011-01-01

    Hydrophobicity is a very important surface property and there is a growing interest in the production and characterization of superhydrophobic surfaces. Accordingly, it was recently shown how to obtain a superhydrophobic surface using a simple and cost-effective method on a polymer named poly(L-lactic acid) (PLLA). To evaluate the ability of such material as a substrate for bacterial colonization, this work assessed the capability of different bacteria to colonize a biomimetic rough superhydrophobic (SH) PLLA surface and also a smooth hydrophobic (H) one. The interaction between these surfaces and bacteria with different morphologies and cell walls was studied using one strain of Staphylococcus aureus and one of Pseudomonas aeruginosa. Results showed that both bacterial strains colonized the surfaces tested, although significantly higher numbers of S. aureus cells were found on SH surfaces comparing to H ones. Moreover, scanning electron microscopy images showed an extracellular matrix produced by P. aeruginosa on SH PLLA surfaces, indicating that this bacterium is able to form a biofilm on such substratum. Bacterial removal through lotus leaf effect was also tested, being more efficient on H coupons than on SH PLLA ones. Overall, the results showed that SH PLLA surfaces can be used as a substrate for bacterial colonization and, thus, have an exceptional potential for biotechnology applications. PMID:22018163

  8. Poly-L-lactic acid/hydroxyapatite electrospun nanocomposites induce chondrogenic differentiation of human MSC.

    PubMed

    Spadaccio, Cristiano; Rainer, Alberto; Trombetta, Marcella; Vadalá, Gianluca; Chello, Massimo; Covino, Elvio; Denaro, Vincenzo; Toyoda, Yoshiya; Genovese, Jorge A

    2009-07-01

    Cartilage and bone tissue engineering has been widely investigated but is still hampered by cell differentiation and transplant integration issues within the constructs. Scaffolds represent the pivotal structure of the engineered tissue and establish an environment for neo-extracellular matrix synthesis. They can be associated to signals to modulate cell activity. In this study, considering the well reported role of hydroxyapatite (HA) in cartilage repair, we focused on the putative chondrogenic differentiation of human mesenchymal stem cells (hMSCs) following culture on membranes of electrospun fibers of poly-L-lactic acid (PLLA) loaded with nanoparticles of HA. hMSCs were seeded on PLLA/HA and bare PLLA membranes and cultured in basal medium, using chondrogenic differentiation medium as a positive control. After 14 days of culture, SOX-9 positive cells could be detected in the PLLA/HA group. Cartilage specific proteoglycan immunostain confirmed the presence of neo-extracellular-matrix production. Co-expression of CD29, a typical surface marker of MSCs and SOX-9, suggested different degrees in the differentiation process. We developed a hydroxyapatite functionalized scaffold with the aim to recapitulate the native histoarchitecture and the molecular signaling of osteochondral tissue to facilitate cell differentiation toward chondrocyte. PLLA/HA nanocomposites induced differentiation of hMSCs in a chondrocyte-like phenotype with generation of a proteoglycan based matrix. This nanocomposite could be an amenable alternative scaffold for cartilage tissue engineering using hMSCs. PMID:19418224

  9. Free-standing poly(L-lactic acid) nanofilms loaded with superparamagnetic nanoparticles.

    PubMed

    Taccola, Silvia; Desii, Andrea; Pensabene, Virginia; Fujie, Toshinori; Saito, Akihiro; Takeoka, Shinji; Dario, Paolo; Menciassi, Arianna; Mattoli, Virgilio

    2011-05-01

    Freely suspended nanocomposite thin films based on soft polymers and functional nanostructures have been widely investigated for their potential application as active elements in microdevices. However, most studies are focused on the preparation of nanofilms composed of polyelectrolytes and charged colloidal particles. Here, a new technique for the preparation of poly(l-lactic acid) free-standing nanofilms embeddidng superparamagnetic iron oxide nanoparticles is presented. The fabrication process, based on a spin-coating deposition approach, is described, and the influence of each production parameter on the morphology and magnetic properties of the final structure is investigated. Superparamagnetic free-standing nanofilms were obtained, as evidenced by a magnetization hysteresis measurement performed with a superconducting quantum interference device (SQUID). Nanofilm surface morphology and thickness were evaluated by atomic force microscopy (AFM), and the nanoparticle dispersion inside the composites was investigated by transmission electron microscopy (TEM). These nanofilms, composed of a biodegradable polyester and remotely controllable by external magnetic fields, are promising candidates for many potential applications in the biomedical field. PMID:21456538

  10. Evaluation of a poly(L-lactic acid) stent for sutureless vascular anastomosis.

    PubMed

    Nakano, Yoshiyuki; Hori, Yoshio; Sato, Akira; Watanabe, Tetsuo; Takada, Shuji; Goto, Hitoshi; Inagaki, Akiko; Ikada, Yoshito; Satomi, Susumu

    2009-03-01

    We have developed a sutureless anastomosis device consisting of a biodegradable stent and stainless steel band for end-to-end anastomosis. The aim of this acute phase study was to evaluate the feasibility of a sutureless anastomotic procedure with a bioabsorbable stent during a 4-week period in a swine model. The porcine infrarenal aorta was replaced with an expanded polytetrafluoroethylene graft. A proximal anastomosis was completed using a sutureless anastomotic procedure employing a bioabsorbable stent made of poly(L-lactic acid) (PLLA) and a stainless steel plate. A distal anastomosis completed by manual suturing served as a control. At 4 weeks after surgery, angiography was performed. The animals were then killed, and the specimens were evaluated histologically. The sutureless anastomotic procedure required significantly less time than the suturing technique. Angiograms showed patency of the grafts, and no signs of either stenosis or leakage. Both pressure-proof and tensile tests confirmed the adequate mechanical strength of the anastomoses. Sutureless anastomosis with a PLLA stent appears to be feasible, at least within an observation period of 4 weeks. This simple procedure shortened the time of surgery and would contribute to reducing the risks of operation-related complications. PMID:18774683

  11. Fabrication and biocompatibility of poly(l-lactic acid) and chitosan composite scaffolds with hierarchical microstructures.

    PubMed

    Lou, Tao; Wang, Xuejun; Yan, Xu; Miao, Yu; Long, Yun-Ze; Yin, Hai-Lei; Sun, Bin; Song, Guojun

    2016-07-01

    The scaffold microstructure is crucial to reconstruct tissue normal functions. In this article, poly(l-lactic acid) and chitosan fiber (PLLA/CTSF) composite scaffolds with hierarchical microstructures both in fiber and pore sizes were successfully fabricated by combining thermal induced phase separation and salt leaching techniques. The composite scaffolds consisted of a nanofibrous PLLA matrix with diameter of 50-500nm, and chitosan fibers with diameter of about 20μm were homogenously distributed in the PLLA matrix as a microsized reinforcer. The composite scaffolds also had high porosity (>94%) and hierarchical pore size, which were consisted of both micropores (50nm-10μm) and macropores (50-300μm). By tailoring the microstructure and chemical composition, the mechanical property, pH buffer and protein adsorption capacity of the composite scaffold were improved significantly compared with those of PLLA scaffold. Cell culture results also revealed that the PLLA/CTSF composite scaffolds supported MG-63 osteoblast proliferation and penetration. PMID:27127062

  12. Poly(L-lactic acid)/poly(glycolic acid) microfibrillar polymer-polymer composites: Preparation and viscoelastic properties

    NASA Astrophysics Data System (ADS)

    Kimble, L. D.; Fakirov, S.; Bhattacharyya, D.

    2015-05-01

    Microfibrillar composites (MFCs) from petrochemical-derived polymers have been investigated for several years and the technique can result in significant improvements in mechanical properties when compared with the neat matrix material of the respective composite. The current work applies the technique to biodegradable, biocompatible polymers for potential applications in bioabsorbable medical devices. MFCs were prepared from melt blended poly(L-lactic acid) (PLLA) and poly(glycolic acid) (PGA) via cold drawing then compression molding of extruded yarn. These MFCs were shown to have higher Young's moduli than that of neat PLLA but for load-bearing applications the creep characteristics are of interest. The MFC sheets resulting from compression molding were subjected to tensile relaxation tests at 37°C in the fiber orientation direction. Specimens were also tested via dynamic mechanical thermal analysis (DMTA). Neat PLLA specimens were subjected to the same tests for comparison. Results indicate that at 37°C PLLA/PGA MFCs exhibit lower creep resistance than that of neat PLLA due to the more rapid relaxation of stress observed. DMTA results elucidate the loss modulus changes in PLLA/PGA MFCs which occur as the material approaches the glass transition temperature of PGA (˜45°C).

  13. Experimental Study of Poly-l-Lactic Acid Biodegradable Stents in Normal Canine Bile Ducts

    SciTech Connect

    Yamamoto, Kiyosei Yoshioka, Tetsuya; Furuichi, Kinya; Sakaguchi, Hiroshi; Anai, Hiroshi; Tanaka, Toshihiro; Morimoto, Kengo; Uchida, Hideo; Kichikawa, Kimihiko

    2011-06-15

    Purpose: This study was designed to clarify the advantages of biodegradable stents in terms of mucosal reaction and biodegradation after placement. We designed a biodegradable stent and assessed stent degradation and changes in the normal bile ducts of dogs. Methods: The biodegradable stent is a balloon-expandable Z stent consisting of poly-l-lactic acid (PLLA) with a diameter of 6 mm and a length of 15 mm. We assessed four groups of three beagle dogs each at 1, 3, 6, and 9 months of follow-up. After evaluating stent migration by radiography and stent and bile duct patency by cholangiography, the dogs were sacrificed to remove the bile duct together with the stent. The bile duct lumen was examined macroscopically and histologically, and the stent degradation was examined macroscopically and by scanning electron microscopy (SEM). Results: Bile duct obstruction was absent and none of the stents migrated. Macroscopic evaluation showed moderate endothelial proliferation in the bile ducts at the implant sites at 3 and 6 months and a slight change at 9 months. Slight mononuclear cell infiltration was histologically identified at all time points and epithelial hyperplasia that was moderate at 3 months was reduced to slight at 6 and 9 months. Stent degradation was macroscopically evident in all animals at 9 months and was proven by SEM in two dogs at 6 months and in all of them at 9 months. Conclusions: Our results suggest that PLLA bioabsorbable stents seems to be useful for implantation in the biliary system with further investigation.

  14. Embedding methods for poly(L-lactic acid) microfiber mesh/human mesenchymal stem cell constructs.

    PubMed

    D'Alessandro, D; Battolla, B; Trombi, L; Barachini, S; Cascone, M G; Bernardini, N; Petrini, M; Mattii, L

    2009-01-01

    Fiber mesh scaffolds were recently investigated in tissue engineering as possible support for stem cell growth and differentiation, in order to repair lesion areas in clinical practice. In particular, the literature is focused on fiber mesh scaffolds constituted of biocompatible and resorbable polymeric structures, like poly(L-lactic acid) (PLLA). However, as regards the study of constructs constituted of PLLA microfibers and cells, only quantitative and SEM analyses were reported, lacking histological analysis. Histological evaluation of these constructs could give important information about cellular distribution in the scaffold, cell-scaffold interactions and extracellular matrix production. The purpose of our study was to find a valid method to analyze PLLA microfiber/cell constructs from both histological and histochemical angles. Biodegradable non-woven fiber meshes were prepared using hollow microfibers, based on PLLA. We first evaluated different embedding methods useable for histological analysis and the results showed that among the paraffin, Killik, and acrylic resin the only suitable medium was the latter. Then we employed the acrylic resin to embed the constructs made up of PLLA microfibers and bone marrow-derived human mesenchymal stromal cells, which we then analyzed with Toluidine Blue, PAS and Alcian Blue staining. These constructs, previously analyzed for cell viability by MTT and CCK-8 tests, showed viable/proliferating cells until 6 weeks of culture. The stainings performed on constructs confirmed viability data obtained with SEM and MTT/CCK-8 and supplied other information on the cell behaviors such as the distribution and organization onto the scaffold and the production of extracellular matrix molecules. In conclusion, this methodological study mainly suggests a suitable method to analyze PLLA microfiber/cell constructs, at the same time confirming and enriching the literature data on the compatibility between PLLA microfibers and hMSCs. PMID

  15. Modification of poly(L-lactic acid) electrospun fibers and films with poly(propylene imine) dendrimer

    NASA Astrophysics Data System (ADS)

    Khaliliazar, Sh.; Akbari, S.; Kish, M. H.

    2016-02-01

    Poly(L-lactic acid) (PLLA) electrospun fibers and films were modified with the second generation of poly(propylene imine) dendrimer (PPI-G2) by three different approaches, namely, sodium hydroxide hydrolysis, plasma treatment and direct application of PPI-G2. For the first and the second approaches, PLLA was modified by sodium hydroxide hydrolysis or plasma treatment to produce carboxylic acid groups. Then, the carboxylic acid groups were activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) and N,N‧-dicyclohexyl carbodiimide (DCC) as a hetero bi-functional cross-linker. The cross-linkers promoted the grafting of carboxylic acid groups on the modified PLLA with NH2 groups of PPI-G2. In the third approach, the PPI-G2 dendrimer was directly used as an aminolysis agent for the functionalization of PLLA in a one step process. FTIR analysis confirmed the presence of sbnd NH2 groups of PPI-G2 on the modified PLLA samples, resulting from each one of the three modification methods. Studies by SEM shows bead free electrospun fibers. Also, FE-SEM shows nano-cracks on the surface of films after modification. Contact angle, drug release tests, antibacterial effects and the dying results confirmed that these functionalization methods increased hydrophilicity and reactive side-chains of PLLA in the wet chemical process resulted in providing host-guest properties on the PLLA surface for adsorbing various kinds of guest molecules.

  16. Optimizing facial rejuvenation outcomes by combining poly-L-lactic acid, hyaluronic acid, calcium hydroxylapatite, and neurotoxins: two case studies.

    PubMed

    Lorenc, Z Paul; Daro-Kaftan, Elizabeth

    2014-02-01

    Reversal of the visible signs of facial aging with the use of injectable products as an alternative to surgery has become more popular, with nearly 5 million procedures performed in the United States in 2012. Volume augmentation products, such as hyaluronic acid (HA), calcium hydroxylapatite (CaHA), and poly-L-lactic acid (PLLA), are often used in combination with one another and with neurotoxins for facial rejuvenation because of the complementary modes of action. This article presents 2 case reports involving patientspecific combinations of 2 different HA products, injectable PLLA, and CaHA with incobotulinumtoxinA or abobotulinumtoxinA. The combination of HA, CaHA, PLLA, and neurotoxins has resulted in outstanding outcomes for many patients, with no clinical evidence of increased adverse events secondary to combination therapy. PMID:24509971

  17. Creation of highly aligned electrospun poly-L-lactic acid fibers for nerve regeneration applications

    NASA Astrophysics Data System (ADS)

    Wang, Han Bing; Mullins, Michael E.; Cregg, Jared M.; Hurtado, Andres; Oudega, Martin; Trombley, Matthew T.; Gilbert, Ryan J.

    2009-02-01

    Aligned, electrospun polymer fibers have shown considerable promise in directing regenerating axons in vitro and in vivo. However, in several studies, final electrospinning parameters are presented for producing aligned fiber scaffolds, and alignment where minimal fiber crossing occurs is not achieved. Highly aligned species are necessary for neural tissue engineering applications to ensure that axonal extension occurs through a regenerating environment efficiently. Axonal outgrowth on fibers that deviate from the natural axis of growth may delay axonal extension from one end of a scaffold to the other. Therefore, producing aligned fiber scaffolds with little fiber crossing is essential. In this study, the contributions of four electrospinning parameters (collection disk rotation speed, needle size, needle tip shape and syringe pump flow rate) were investigated thoroughly with the goal of finding parameters to obtain highly aligned electrospun fibers made from poly-L-lactic acid (PLLA). Using an 8 wt% PLLA solution in chloroform, a collection disk rotation speed of 1000 revolutions per minute (rpm), a 22 gauge, sharp-tip needle and a syringe pump rate of 2 ml h-1 produced highly aligned fiber (1.2-1.6 µm in diameter) scaffolds verified using a fast Fourier transform and a fiber alignment quantification technique. Additionally, the application of an insulating sheath around the needle tip improved the rate of fiber deposition (electrospinning efficiency). Optimized scaffolds were then evaluated in vitro using embryonic stage nine (E9) chick dorsal root ganglia (DRGs) and rat Schwann cells (SCs). To demonstrate the importance of creating highly aligned scaffolds to direct neurite outgrowth, scaffolds were created that contained crossing fibers. Neurites on these scaffolds were directed down the axis of the aligned fibers, but neurites also grew along the crossed fibers. At times, these crossed fibers even stopped further axonal extension. Highly aligned PLLA fibers

  18. Stereocomplexation of low molecular weight poly(L-lactic acid) and high molecular weight poly(D-lactic acid), radiation crosslinking PLLA/PDLA stereocomplexes and their characterization

    NASA Astrophysics Data System (ADS)

    Quynh, Tran Minh; Mai, Hoang Hoa; Lan, Pham Ngoc

    2013-02-01

    Poly(L-lactic acid)s (PLLAx) were synthesized from L-lactic acid by polycondensation. Different stereocomplexes were also obtained with equimolar mixtures of synthesized PLLAx and a commercial PDLA. The stereocomplexes were crosslinked with triallyl isocyanurate (TAIC) by gamma irradiation. Crosslinking density increased with radiation doses, the heavier the crosslinking network, the lower its swelling degree. The crosslinking structures were introduced in the stereocomplexes inhibiting the mobility for crystallization of PLLA molecules. Thermal and mechanical properties of PLA stereocomplexes were remarkably enhanced by radiation induced crosslinking. PLA stereocomplex does not seem to be degraded by PLLA degrading microorganisms existing in compost at room temperature, but the synthesized PLLA was significantly degraded.

  19. Unusual large-pitch banding in poly(L-lactic acid): Effects of composition and geometry confinement

    SciTech Connect

    Woo, Eamor M.; Lugito, Graecia; Hsieh, Ya-Ting; Nurkhamidah, Siti

    2014-02-24

    Lamellar patterns and orientations in blends of two crystalline polymers: poly(ethylene oxide) (PEO) and low-molecular-weight poly(L-lactic acid) (PLLA) were investigated using polarizing light optical microscopy (POM), and atomic and scanning electron microscopy (AFM, SEM). Specific etching off of PEO was used to reveal the complex earlier-grown PLLA lamellae patterns with various PEO content in blends. Banding of extremely long pitch (50 μm) in crystallized PLLA spherulites was induced by two kinetic factors: geometry confinement by top cover and introduction of diluent such as PEO. The mechanisms and correlation among the lamellar assembly, ring bands, and cracks are exemplified. Lamellar patterns and ring-band types in blends were found to vary with respect to not only blend compositions, but also confinement of top-cover.

  20. Fabrication of conductive NGF-conjugated polypyrrole-poly(l-lactic acid) fibers and their effect on neurite outgrowth.

    PubMed

    Zeng, Jingwen; Huang, Zhongbing; Yin, Guangfu; Qin, Jiabang; Chen, Xianchun; Gu, Jianwen

    2013-10-01

    In order to fabricate a tissue scaffold with the neurotrophic and electrical activities, conductive nerve growth factor (NGF)-conjugated polypyrrole-poly(l-lactic acid) (PPy-PLLA) composite fibers were prepared by oxidation polymerization and EDC chemistry with poly-l-lysine. PPy nanoparticles (∼70nm diameter) accumulated on PLLA fiber surface to form a rough thick shell (∼200nm thickness). These NGF-conjugated PPy-PLLA fibers could support PC12 neurite outgrowth and extension. Especially, 40% and 74% increase in PC12 neurite outgrowth and extension, respectively, could be obtained under electrical stimulation of 100mV/cm voltages through the composite fibers. A mechanism for the interaction between neurite extension and the NGF-conjugated PPy-PLLA fibers under electro-stimulation was proposed, to explain the synergistic effect of the rough PPy shell, conjugated NGF and electricity on neurite outgrowth and elongation. PMID:23759386

  1. Consensus recommendations on the use of injectable poly-L-lactic acid for facial and nonfacial volumization.

    PubMed

    Vleggaar, Danny; Fitzgerald, Rebecca; Lorenc, Z Paul; Andrews, J Todd; Butterwick, Kimberly; Comstock, Jody; Hanke, C William; O'Daniel, T Gerald; Palm, Melanie D; Roberts, Wendy E; Sadick, Neil; Teller, Craig F

    2014-04-01

    Poly-L-lactic acid (PLLA) was approved for use in Europe in 1999. In the United States, it was approved by the Food and Drug Administration in 2004 for the treatment of facial lipoatrophy associated with human immunodeficiency virus, and in 2009 for cosmetic indications in immune-competent patients. The need for consistent, effective PLLA usage recommendations is heightened by an increased consumer demand for soft tissue augmentation and a shift toward a younger demographic. Over the past 14 years, considerable experience has been gained with this agent, and we have come to better understand the clinical, technical, and mechanistic aspects of PLLA use that need to be considered to optimize patient outcomes. These consensus recommendations regarding patient selection, proper preparation and storage, optimal injection techniques, and other practical considerations reflect the body of evidence in the medical literature, as well as the collective experience of this author group. PMID:24719078

  2. Porous poly(L-lactic acid) sheet prepared by stretching with starch particles as filler for tissue engineering.

    PubMed

    Ju, Dandan; Han, Lijing; Li, Zonglin; Chen, Yunjing; Wang, Qingjiang; Bian, Junjia; Dong, Lisong

    2016-05-20

    Porous poly(L-lactic acid) (PLLA) sheets were prepared by uniaxial stretching PLLA sheets containing starch filler. Here, the starch filler content, stretching ratio, stretching rate and stretching temperature are important factors to influence the structure of the porous PLLA sheets, therefore, they have been investigated in detail. The pore size distribution and tortuosity were characterized by Mercury Intrusion Porosimetry. The results revealed that the porosity and pore size enlarged with the increase of the starch filler content and stretching ratio, while shrank with the rise of stretching temperature. On the other hand, the pore structure almost had no changes with the stretching rate ranging between 5 and 40 mm/min. In order to test and verify that the porous PLLA sheet was suitable for the tissue engineering, the starch particles were removed by selective enzymatic degradation and its in vitro biocompatibility to osteoblast-like MC3T3-E1 cells was investigated. PMID:26917394

  3. In vitro and in vivo characterization of porous poly-l-lactic acid coatings for subcutaneously implanted glucose sensors

    PubMed Central

    Koschwanez, H. E.; Yap, F. Y.; Klitzman, B.; Reichert, W. M.

    2014-01-01

    The purpose of this study was to test the hypothesis that porous poly-l-lactic acid (PLLA) sensor coatings reduce fibrosis and promote blood microvessel formation in tissue adjacent to the sensor surface. Porous PLLA coatings were produced using ammonium bicarbonate as the gas foaming/salt leaching agent, and deployed on functional and nonfunctional sensors. The porous coatings minimally affected sensor accuracy and response rate in vitro. Three-week subcutaneous rat studies of nonfunctional glucose sensors showed the anticipated effect of porous coatings enhancing vascularity and decreasing collagen deposition. In contrast, percutaneous functional sensors with and without porous coatings showed no significant difference in terms of histology or sensor response. In spite of the observation that texturing increases the vascularity of the tissue that surrounds implanted sensors, other factors such as the additional mechanical stresses imposed by percutaneous tethering may override the beneficial effects of the porous coatings. PMID:18200540

  4. Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

    SciTech Connect

    Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Hinata, Toru; Washio, Masakazu; Oshima, Akihiro; Tagawa, Seiichi

    2013-10-14

    Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  5. Fabrication and characterization of poly(L-lactic acid) gels induced by fibrous complex crystallization with solvents

    SciTech Connect

    Matsuda, Yasuhiro; Fukatsu, Akinobu; Wang, Yangyang; Miyamoto, Kazuaki; Mays, Jimmy; Tasaka, Shigeru

    2014-01-01

    Complex crystal induced gelation of poly(L-lactic acid) (PLLA) solutions was studied for a series of solvents, including N,N-dimethylformamide (DMF). By cooling the solutions prepared at elevated temperatures, PLLA gels were produced in solvents that induced complex crystals ( -crystals) with PLLA. Fibrous structure of PLLA in the gel with DMF was observed by polarizing optical microscopy, field emission electron microscopy, and atomic force microscopy. Upon heating, the crystal form of PLLA in the DMF gel changed from -crystal to a-crystal, the major crystal form in common untreated PLLA films, but the morphology and high elastic modulus of the gel remained until the a-crystal dissolved at higher temperature. In addition, a solvent exchanging method was developed, which allowed PLLA gels to be prepared in other useful solvents that do not induce -crystals without losing the morphology and mechanical properties.

  6. Polymorphic Crystallization and Crystalline Reorganization of Poly(l-lactic acid)/Poly(d-lactic acid) Racemic Mixture Influenced by Blending with Poly(vinylidene fluoride).

    PubMed

    Yu, Chengtao; Han, Lili; Bao, Jianna; Shan, Guorong; Bao, Yongzhong; Pan, Pengju

    2016-08-18

    The effects of poly(vinylidene fluoride) (PVDF) on the crystallization kinetics, competing formations of homocrystallites (HCs) and stereocomplexes (SCs), polymorphic crystalline structure, and HC-to-SC crystalline reorganization of the poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic mixture were investigated. Even though the PLLA/PDLA/PVDF blends are immiscible, blending with PVDF enhances the crystallization rate and SC formation of PLLA/PDLA components at different temperatures that are higher or lower than the melting temperature of the PVDF component; it also facilitates the HC-to-SC melt reorganization upon heating. The crystallization rate and degree of SC crystallinity (Xc,SC) of PLLA/PDLA components in nonisothermal crystallization increase after immiscible blending with PVDF. At different isothermal crystallization temperatures, the crystallization half-time of PLLA/PDLA components decreases; its spherulitic growth rate and Xc,SC increase as the mass fraction of PVDF increases from 0 to 0.5 in the presence of either a solidified or a molten PVDF phase. The HCs formed in primary crystallization of PLLA/PDLA components melt and recrystallize into SCs upon heating; the HC-to-SC melt reorganization is promoted after blending with PVDF. We proposed that the PVDF-promoted crystallization, SC formation, and HC-to-SC melt reorganization of PLLA/PDLA components in PLLA/PDLA/PVDF blends stem from the enhanced diffusion ability of PLLA and PDLA chains. PMID:27414064

  7. Biodegradable poly(D,L-lactic acid)-poly(ethylene glycol)-monomethyl ether diblock copolymers: structures and surface properties relevant to their use as biomaterials.

    PubMed

    Lucke, A; Tessmar, J; Schnell, E; Schmeer, G; Göpferich, A

    2000-12-01

    To obtain biodegradable polymers with variable surface properties for tissue culture applications, poly(ethylene glycol) blocks were attached to poly(lactic acid) blocks in a variety of combinations. The resulting poly(D,L-lactic acid)-poly(ethylene glycol)-monomethyl ether (Me.PEG-PLA) diblock copolymers were subject to comprehensive investigations concerning their bulk microstructure and surface properties to evaluate their suitability for drug delivery applications as well as for the manufacture of scaffolds in tissue engineering. Results obtained from 1H-NMR, gel permeation chromatography, wide angle X-ray diffraction and modulated differential scanning calorimetry revealed that the polymer bulk microstructure contains poly(ethylene glycol)-monomethyl ether (Me.PEG) domains segregated from poly(D,L-lactic acid) (PLA) domains varying with the composition of the diblock copolymers. Analysis of the surface of polymer films with atomic force microscopy and X-ray photoelectron spectroscopy indicated that there is a variable amount of Me.PEG chains present on the polymer surface, depending on the polymer composition. It could be shown that the presence of Me.PEG chains in the polymer surface had a suppressive effect on the adsorption of two model peptides (salmon calcitonin and human atrial natriuretic peptide). The possibility to modify polymer bulk microstructure as well as surface properties by variation of the copolymer composition is a prerequisite for their efficient use in the fields of drug delivery and tissue engineering. PMID:11055283

  8. Degradation of Poly(L-Lactic acid) and Biocomposites in various Alkaline and Temperature Treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ribbons of poly(lactic acid) (PLA) and PLA containing 10 or 25 % Osage orange (OO) biocomposites of various sized heartwood particles were exposed to soil conditions either outdoors or in a greenhouse. No appreciable degradation was evident even after 200 days treatments. An artificial alkaline de...

  9. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

    PubMed Central

    Yang, Gesheng; Pastorino, Laura

    2016-01-01

    Summary The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA)n stereocomplex and the cores with and without the polymeric (PSS/PAH)n/PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  10. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes.

    PubMed

    Dellacasa, Elena; Zhao, Li; Yang, Gesheng; Pastorino, Laura; Sukhorukov, Gleb B

    2016-01-01

    The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA) n stereocomplex and the cores with and without the polymeric (PSS/PAH) n /PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  11. Processing and size range separation of pristine and magnetic poly(l-lactic acid) based microspheres for biomedical applications.

    PubMed

    Correia, D M; Sencadas, V; Ribeiro, C; Martins, P M; Martins, P; Gama, F M; Botelho, G; Lanceros-Méndez, S

    2016-08-15

    Biodegradable poly(l-lactic acid) (PLLA) and PLLA/CoFe2O4 magnetic microspheres with average sizes ranging between 0.16-3.9μm and 0.8-2.2μm, respectively, were obtained by an oil-in-water emulsion method using poly(vinyl alcohol) (PVA) solution as the emulsifier agent. The separation of the microspheres in different size ranges was then performed by centrifugation and the colloidal stability assessed at different pH values. Neat PLLA spheres are more stable in alkaline environments when compared to magnetic microspheres, both types being stable for pHs higher than 4, resulting in a colloidal suspension. On the other hand, in acidic environments the microspheres tend to form aggregates. The neat PLLA microspheres show a degree of crystallinity of 40% whereas the composite ones are nearly amorphous (17%). Finally, the biocompatibility was assessed by cell viability studies with MC3T3-E1 pre-osteoblast cells. PMID:27209393

  12. Fabrication and Protein Conjugation of Aligned Polypyrrole-Poly(L-lactic acid) Fibers Film with the Conductivity and Stability.

    PubMed

    Qin, Jiabang; Huang, Zhongbing; Yin, Guangfu; Yang, Anneng; Han, Wei

    2016-03-01

    The conducting composite scaffold, including fiber-cores of aligned poly(L-lactic acid) (PLLA) and shell-layer of polypyrrole (PPy), was fabricated, and then bovine serum albumin (BSA) was conjugated on the PPy shell-layer. Aligned PLLA fibers (about 300 nm diameter) were obtained by electrospinning and rotating drum collection, and then coated by PPy nanoparticles (NPs, about 50 nm diameter) via chemical oxidation. The surface resistivity of PPy-PLLA fibers film were 0.971, 0.874 kΩ. cm at the fiber's vertical and parallel directions, respectively. The results of PPy-PLLA fibers film immersed in phosphate buffer saline for 8 d indicated that the fibers morphology and the film conductivity were not significantly changed, and the fluorescent images showed that FITC-labeled BSA (FITC-BSA) were successfully conjugated in the fibers film with carbodiimide chemistry, and the largest amount of FITC-BSA conjugated in the fibers film from 100 μg/mL proteins solution was 31.31 μg/cm2 due to lots of poly(glutamic acid) in surface-nanogrooves of the fibers surface. Under electrical stimulation of 100 mV, the fibers film was accompanied the release of all conjugated FITC-BSA with the detachment of some PPy NPs. These results suggested that PPy-PLLA fibers film would be potentially applied in the construction of degradable tissue engineering scaffold with protein factors, especially neurotrophic factors for nerve tissue repair. PMID:27455643

  13. Dexamethasone-loaded poly(D, L-lactic acid) microspheres/poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) micelles composite for skin augmentation.

    PubMed

    Fan, Min; Liao, Jinfeng; Guo, Gang; Ding, Qiuxia; Yang, Yi; Luo, Feng; Qian, Zhiyong

    2014-04-01

    Soft tissue augmentation using various injectable fillers has gained popularity as more patients seek esthetic improvement through minimally invasive procedures requiring little or no recovery time. The currently available injectable skin fillers can be divided into three categories. With careful assessment, stimulatory fillers are the most ideal fillers. In this study, dexamethasone-loaded poly(D, L-lactic acid) (PLA) microspheres of approximately 90 micro m suspended in poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) micelles were prepared as stimulatory filler for skin augmentation. The biodegradable PECE copolymer can form nano-sized micelles in water, which instantly turns into a non-flowing gel at body temperature due to micellar aggregation. The PECE micelles (making up 90% of composite) served as vehicle for subcutaneous injection were metabolized within 44 days. At the same time, the dexamethasone-loaded PLA microspheres (10% of composite) merely served as stimulus for connective tissue formation. Dexamethasone-loaded PLA microspheres/PECE micelles composite presented great hemocompatibility in vitro. It was demonstrated in the in vive study that the composite was biodegradable, biocompatible, nontoxic and nonmigratory. Histopathological studies indicated that the composite could stimulate collagen regeneration. Furthermore, granuloma, the main complication of the stimulatory fillers, did not appear when the composite was injected into the back of SD rats, because of the dexamethasone controlled release from the composite. All results suggested that dexamethasone-loaded PLA microspheres/PECE micelles composite may be an efficient and promising biomaterial for skin augmentation. PMID:24734511

  14. Preparation of porous poly(L-lactic acid) honeycomb monolith structure by phase separation and unidirectional freezing.

    PubMed

    Kim, Jin-Woong; Taki, Kentaro; Nagamine, Shinsuke; Ohshima, Masahiro

    2009-05-01

    A honeycomb monolith structure with micro/nanoscale porous walls was successfully fabricated in poly(l-lactic acid) (PLLA) by integrating polymer-solvent and polymer-polymer phase separations induced during a pseudosteady-state unidirectional freezing process. Poly(ethylene glycol) (PEG) and PLLA were dissolved in 1,4-dioxane to prepare a single phase polymer solution. The direction of freezing created a honeycomb monolith structure of PLLA/PEG polymers. Crystallization of the solvent reduced the solvent concentration and induced liquid-liquid phase separation during the unidirectional freezing. A sea-and-island morphology, where PEG domains were dispersed in the PLLA matrix, was developed, and pores were created in the channel walls of the honeycomb monolith structure by leaching out the PEG domain. The effects of the PEG molecular weight and the PLLA/PEG weight ratio on the aligned honeycomb structure and the pores in the channel walls were investigated. A ternary phase diagram for PLLA, PEG, and 1,4-dioxane was created from cloud point temperature measurements. Based on this phase diagram, hypotheses for the mechanism of the cellular-dendritic transition and the formation mechanism of the pores in the channel walls are proposed. PMID:19290649

  15. The Interactions Between Aligned Poly(L-Lactic Acid) Nanofibers and SH-SY5Y Cells In Vitro.

    PubMed

    Yu, Yadong; Meng, Dianhuai; Man, Lili; Wang, Xin

    2016-06-01

    Aligned nanofibers have been regarded as promising nanomaterials in facilitating nerve regeneration. Investigating the interactions between aligned nanofibers and neuronal cells will be critically important for the design and application of aligned nanofibers in nerve tissue engineering. In this study, we explored the effects of electrospun Poly(L-Lactic Acid) (PLLA) aligned nanofibers on SH-SY5Y cells (a type of human neuroblastoma cell line) and specifically focused on the role of integrin in the PLLA aligned nanofiber-SH-SY5Y cell interaction. We found that PLLA aligned nanofibers could significantly guide the neurite outgrowth of SH-SY5Y cell, and promote the viability, proliferation, glucose and lactic acid metabolism of SH-SY5Y cell. This promotion effect could be alleviated when the functions of integrins on the SH-SY5Y cell membrane were hampered by pentapeptide GRGDS. Moreover, we found that PLLA aligned nanofibers could enhance the expression of phosphorylated-ERK1/2 (p-ERK1/2) in the SH-SY5Y cells and blocking the integrins would decrease p-ERK1/2 expression. These results suggested that PLLA aligned nanofibers might affect many cellular behaviors of SH-SY5Y cells via integrin mediated ERK pathway. Our findings provided more insights for understanding the interaction between aligned nanofibers and neuronal cells. PMID:27427727

  16. Differentiation of neuronal stem cells into motor neurons using electrospun poly-L-lactic acid/gelatin scaffold.

    PubMed

    Binan, Loïc; Tendey, Charlène; De Crescenzo, Gregory; El Ayoubi, Rouwayda; Ajji, Abdellah; Jolicoeur, Mario

    2014-01-01

    Neural stem cells (NSCs) provide promising therapeutic potential for cell replacement therapy in spinal cord injury (SCI). However, high increases of cell viability and poor control of cell differentiation remain major obstacles. In this study, we have developed a non-woven material made of co-electrospun fibers of poly L-lactic acid and gelatin with a degradation rate and mechanical properties similar to peripheral nerve tissue and investigated their effect on cell survival and differentiation into motor neuronal lineages through the controlled release of retinoic acid (RA) and purmorphamine. Engineered Neural Stem-Like Cells (NSLCs) seeded on these fibers, with and without the instructive cues, differentiated into β-III-tubulin, HB-9, Islet-1, and choactase-positive motor neurons by immunostaining, in response to the release of the biomolecules. In addition, the bioactive material not only enhanced the differentiation into motor neuronal lineages but also promoted neurite outgrowth. This study elucidated that a combination of electrospun fiber scaffolds, neural stem cells, and controlled delivery of instructive cues could lead to the development of a better strategy for peripheral nerve injury repair. PMID:24161168

  17. Poly(D,L-lactic-co-glycolic acid) microspheres for sustained delivery and stabilization of camptothecin.

    PubMed

    Ertl, B; Platzer, P; Wirth, M; Gabor, F

    1999-09-20

    Camptothecin (CPT) and its water-insoluble derivatives are known as topoisomerase-I inhibitors exhibiting high antitumoral activity against a wide spectrum of human malignancies. Until now clinical application of CPT is restricted by insolubility and instability of the drug in its active lactone form resulting in less antitumor potency and poor bioavailability. For these reasons CPT-loaded-microspheres were prepared by the solvent evaporation method using the H-series of poly(D,L-lactide-co-glycolide) (H-PLGA), which contain more carboxylic acid end chains and hydrate faster than the non-H-series. At 1.2% CPT-payload the drug was molecular dispersed throughout the matrix whereas at higher CPT-payload the amount of crystalline CPT-islets increased with the CPT content. The release pattern of CPT was biphasic comprising a first burst effect delivering 20-35% of the payload and increasing with drug-loading. This phase was followed by sustained delivery of CPT releasing 40-75% of the payload within 160 h. In comparison to PLGA-microspheres, the CPT-release rate from H-PLGA was twofold higher and accelerated. The active CPT-lactone was maintained during preparation, storage and release due to hindered diffusion of acidic oligomers among other mechanisms. Thus stabilization and sustained release of CPT from PLGA-microspheres might reduce local toxicity combined with prolonged efficacy offering new perspectives in CPT chemotherapy. PMID:10477803

  18. Cytocompatibility of a conductive nanofibrous carbon nanotube/poly (L-Lactic acid) composite scaffold intended for nerve tissue engineering

    PubMed Central

    Kabiri, Mahboubeh; Oraee-Yazdani, Saeed; Dodel, Masumeh; Hanaee-Ahvaz, Hana; Soudi, Sara; Seyedjafari, Ehsan; Salehi, Mohammad; Soleimani, Masoud

    2015-01-01

    The purpose of this study was to fabricate a conductive aligned nanofibrous substrate and evaluate its suitability and cytocompatibility with neural cells for nerve tissue engineering purposes. In order to reach these goals, we first used electrospinning to fabricate single-walled carbon-nanotube (SWCNT) incorporated poly(L-lactic acid) (PLLA) nanofibrous scaffolds and then assessed its cytocompatibility with olfactory ensheathing glial cells (OEC). The plasma treated scaffolds were characterized using scanning electron microscopy and water contact angle. OECs were isolated from olfactory bulb of GFP Sprague-Dawley rats and characterized using OEC specific markers via immunocytochemistry and flow cytometery. The cytocompatibility of the conductive aligned nano-featured scaffold was assessed using microscopy and MTT assay. We indicate that doping of PLLA polymer with SWCNT can augment the aligned nanosized substrate with conductivity, making it favorable for nerve tissue engineering. Our results demonstrated that SWCNT/PLLA composite scaffold promote the adhesion, growth, survival and proliferation of OEC. Regarding the ideal physical, topographical and electrical properties of the scaffold and the neurotrophic and migratory features of the OECs, we suggest this scaffold and the cell/scaffold construct as a promising platform for cell delivery to neural defects in nerve tissue engineering approaches. PMID:26600751

  19. Modification of physical properties of poly(L-lactic acid) by addition of methyl-β-cyclodextrin

    PubMed Central

    Suzuki, Toshiyuki; Ei, Ayaka; Takada, Yoshihisa; Uehara, Hiroki; Takahashi, Keiko

    2014-01-01

    Summary Poly(L-lactic acid) (PLLA) is a biodegradable plastic and one of the most famous plastics made from biobased materials. However, its physical strength is insufficient compared to general-purpose plastics. In this study, the effect of methylcyclodextrin (MeCD) addition on the structure and physical properties, especially the drawing behavior, of PLLA was investigated. Through thermal analysis, it was found that MeCD addition lowers the crystallinity and enhances the mobility of PLLA. The sample containing approximately 17% MeCD was drawn to more than 1000% at 60 °C, although PLLA fractured at a strain of less than 100%. Differential scanning calorimetry (DSC)-Raman in situ measurements also revealed decreases in the glass transition temperature (T g), cold crystallization temperature (T c), and melting point (T m), and improvement in structural distribution with temperature. DSC-Raman measurements simultaneously supplied information about crystallinity and thermal properties. Thus, it was concluded that MeCD had high affinity for PLLA, and the addition of MeCD increased the amorphous component of PLLA and enhanced the drawability. PMID:25670970

  20. Spiral crack patterns observed for melt-grown spherulites of poly(L-lactic acid) upon quenching.

    PubMed

    Matsuda, Futoshi; Sobajima, Takamasa; Irie, Satoshi; Sasaki, Takashi

    2016-04-01

    In this paper, we demonstrate the characteristic spiral cracking that appears on the surface of melt-grown poly(L-lactic acid) (PLLA) spherulites with relatively large sizes (greater than 0.4mm in diameter). The crack occurs via thermal shrinkage upon quenching after crystallization. Although concentric cracks on polymer spherulites have been found to occur in quite a few studies, spiral crack patterns have never been reported so far. The present spiral crack was observed for thick spherulites (> 10 μm), whereas the concentric crack pattern was frequently observed for thin spherulites (typically 5μm). The present PLLA spherulites exhibited a non-banded structure with no apparent structural periodicity at least on the scale of the spiral pitch, and thus no direct correlation between the crack pattern and the spherulitic structure was suggested. The spiral was revealed to be largely Archimedean of which the spiral pitch increases with an increase in the thickness of the spherulite. This may be interpreted in terms of a classical mechanical model for a thin layer with no delamination from the substrate. PMID:27085999

  1. Zidovudine-poly(L-lactic acid) solid dispersions with improved intestinal permeability prepared by supercritical antisolvent process.

    PubMed

    Yoshida, Valquíria M H; Balcão, Victor M; Vila, Marta M D C; Oliveira Júnior, José M; Aranha, Norberto; Chaud, Marco V; Gremião, Maria P D

    2015-05-01

    A supercritical antisolvent (SAS) process for obtaining zidovudine-poly(L-lactic acid) (PLLA) solid dispersions (SDs) was used to attain a better intestinal permeation of this drug. A 3(2) factorial design was used, having as independent variables the ratio 3'-azido-2'3'-dideoxythymidine (AZT)-PLLA and temperature/pressure conditions, as dependent variables the process yield and particle macroscopic morphology. AZT-PLLA production batches were carried out by the SAS process, and the resulting products evaluated via scanning electron microscope, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared analyses. From the nine possible combinations of tests performed experimentally, only one combination did not produced a solid. The L3 batch of SD, produced with 1:2 (AZT-PLLA) ratio, resulted in a 91.54% yield, with 40% AZT content. Intestinal permeability studies using the AZT-PLLA from L3 batch led to an AZT permeability of approximately 9.87%, which was higher than that of pure AZT (∼3.84%). AZT remained in crystalline form, whereas PLLA remained in semicrystalline form. AZT release is controlled by a diffusion mechanism. It has been demonstrated that it is possible to use PLLA carrier and SAS process to obtain SD, in a single step. PMID:25676038

  2. Surface modification of poly(D,L-lactic-co-glycolic acid) nanoparticles using sodium carboxymethyl cellulose as colloidal stabilize.

    PubMed

    Chittasupho, Chuda; Thongnopkoon, Thanu; Kewsuwan, Prartana

    2016-01-01

    Poly(D,L-lactic-co-glycolic acid) nanoparticles (PLGA NPs) have been widely used as drug delivery systems for both small molecules and macromolecules. However, the colloidal stability problem remains unsolved. This study aims to investigate the possibility of using sodium carboxymethyl cellulose (SCMC) as a stabilizing agent of PLGA NPs. In this study, PLGA NPs were fabricated using various concentrations of SCMC (0.01, 0.1 and 0.5% w/v) by solvent displacement method. SCMC coated NPs were characterized using DLS, FTIR, DSC, colorimetric method. Particle size, polydispersity index, zeta potential values and SCMC adsorption increased with SCMC concentration. FTIR spectra, DSC thermograms and results of colorimetry suggested the interaction of SCMC and PLGA NPs. The stability of SCMC coated PLGA NPs was observed during the storage of three weeks in water. The stability of SCMC coated NPs in serum was also evaluated. Cell viability study revealed that there was no toxicity increased when SCMC was used as a stabilizing agent up to a concentration of 0.1% w/v. SCMC coated PLGA NPs bound A549 cells in a time dependent manner and with a greater extent than uncoated PLGA NPs. In conclusion, SCMC can be used to stabilize PLGA NPs by adsorbing on the surface of NPs. PMID:26338259

  3. Microporous Poly(L-Lactic Acid) Membranes Fabricated by Polyethylene Glycol Solvent-Cast/Particulate Leaching Technique

    PubMed Central

    Selvam, Shivaram; Chang, Wenji V.; Nakamura, Tamako; Samant, Deedar M.; Thomas, Padmaja B.; Trousdale, Melvin D.; Mircheff, Austin K.; Schechter, Joel E.

    2009-01-01

    With the eventual goal of developing a tissue-engineered tear secretory system, we found that primary lacrimal gland acinar cells grown on solid poly(L-lactic acid) (PLLA) supports expressed the best histiotypic morphology. However, to be able to perform vectorial transport functions, epithelia must be supported by a permeable substratum. In the present study, we describe the use of a solvent-cast/particulate leaching technique to fabricate microporous PLLA membranes (mpPLLAm) from PLLA/polyethylene glycol blends. Scanning electron microscopy revealed pores on both the air-cured (∼4 μm) and glass-cured sides (<2 μm) of the mpPLLAm. Diffusion studies were performed with mpPLLAm fabricated from 57.1% PLLA/42.9% polyethylene glycol blends to confirm the presence of channelized pores. The data reveal that glucose, L-tryptophan, and dextran (a high molecular weight glucose polymer) readily permeate mpPLLAm. Diffusion of the immunoglobulin G through the mpPLLAm decreased with time, suggesting the possible adsorption and occlusion of the pores. Cells cultured on the mpPLLAm (57.1/42.9 wt%) grew to subconfluent monolayers but retained histiotypic morphological and physiological characteristics of lacrimal acinar cells in vivo. Our results suggest that mpPLLAm fabricated using this technique may be useful as a scaffold for a bioartificial lacrimal gland device. PMID:19260769

  4. Preparation of poly(L-lactic acid) nanofiber scaffolds with a rough surface by phase inversion using supercritical carbon dioxide.

    PubMed

    Yang, Ding-Zhu; Chen, Ai-Zheng; Wang, Shi-Bin; Li, Yi; Tang, Xiao-Lin; Wu, Yong-Jing

    2015-06-01

    Phase inversion using supercritical carbon dioxide (SC-CO2) has been widely used in the development of tissue engineering scaffolds, and particular attention has been given to obtaining desired morphology without additional post-treatments. However, the main challenge of this technique is the difficulty in generating a three-dimensional (3D) nanofiber structure with a rough surface in one step. Here, a poly(L-lactic acid) (PLLA) 3D nanofiber scaffold with a rough surface is obtained via phase inversion using SC-CO2 by carefully choosing fabrication conditions and porogens. It is found that this method can effectively modulate the structure morphology, promote the crystallization process of semicrystalline polymer, and induce the formation of rough structures on the surface of nanofibers. Meanwhile, the porogen of ammonium bicarbonate (AB) can produce a 3D structure with large pores, and porogen of menthol can improve the interconnectivity between the micropores of nanofibers. A significant increase in the fiber diameter is observed as the menthol content increases. Furthermore, the menthol may affect the mutual transition between the α' and α crystals of PLLA during the phase separation process. In addition, the results of protein adsorption, cell adhesion, and proliferation assays indicate that cells tend to have higher viability on the nanofiber scaffold. This process combines the characteristic properties of SC-CO2 and the solubility of menthol to tailor the morphology of polymeric scaffolds, which may have potential applications in tissue engineering. PMID:26107415

  5. Synthesis of antimicrobial Nisin-phosphorylated soybean protein isolate/poly(L-lactic acid)/ZrO2 membranes.

    PubMed

    Jiang, Suwei; Wang, Hualin; Chu, Chenjiang; Ma, Xingkong; Sun, Min; Jiang, Shaotong

    2015-01-01

    Electrospinning technique was used to fabricate the model drug Nisin loaded phosphorylated soybean protein isolate/poly(l-lactic acid)/zirconium dioxide (Nisin-PSPI/PLLA/ZrO2) nanofibrous membranes. The average diameter of drug carrier PSPI/PLLA/ZrO2 nanofibers increased with the increase of content PSPI and some spindle-shape beads appeared when PSPI content reached 25 wt%. The loading dosage of Nisin caused no significant changes in the size and morphology of nanofibers when Nisin content was below 9 wt%. There existed hydrogen and Zr-O-C bonds among PSPI, PLLA and ZrO2 units, and the crystalline of PLLA matrix decreased owning to the introducing of PSPI and ZrO2 units. Moreover, the water absorption capability and degradation rate of PSPI/PLLA/ZrO2 nanofibrous membranes increased with increasing PSPI content. The antimicrobial activity and release experimental results showed that Nisin-PSPI/PLLA/ZrO2 nanofibrous membranes displayed well controlled release and better antimicrobial activity against Staphylococcus aureus (S. aureus), and the Nisin release from the medicated nanofibers could be described by Fickian diffusion model. The Nisin-PSPI/PLLA/ZrO2 nanofibrous membranes may have potential as a new nanofibrous membrane in drug delivery, food active packaging and wound dressing. PMID:25193100

  6. Fabrication and characterization of novel starch-grafted poly l-lactic acid/montmorillonite organoclay nanocomposites.

    PubMed

    Eğri, Özlem; Salimi, Kouroush; Eğri, Sinan; Pişkin, Erhan; Rzayev, Zakir M O

    2016-02-10

    In this work, poly(L-lactic acid)-g-starch layered silicate nanocomposites (NCs) (PLLA-g-starch/MMT) were fabricated by intercalative bulk graft copolymerization of LA with starch, in the presence of either stannous octoate acting as a catalyst or LA-MMT organoclay acting as a cocatalyst-nanofiller. This procedure was performed inside a custom vacuum micro-reactor. To better understand the graft copolymerization mechanism, in situ processing types, interfacial interactions and nanostructure formation of PLLA-g-starch/MMT NCs, methods such as FT-IR, XRD, (1)H NMR, (13)C CP/MAS-NMR, DSC/TGA, TEM and SEM were utilized. The morphology and thermal behaviors of nanocomposites were found to be strongly dependent on the loading mass fraction of LA-MMT within the nanocomposite structure and the type of in situ processing such as interfacial, physical and chemical interactions. Preintercalated LA-MMT organoclay exhibited dual functions. It demonstrated the ability to act as a catalyst, essentially accelerating in situ graft copolymerization via esterification of LA carboxyl groups with hydroxyl groups of starch macromolecules, whilst also acting as a nananofiller-compatibilizer. PMID:26686111

  7. In vitro investigation of nanohydroxyapatite/poly(L-lactic acid) spindle composites used for bone tissue engineering.

    PubMed

    Yan, W; Zhang, C Y; Xia, L L; Zhang, T; Fang, Q F

    2016-08-01

    Calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. In this paper, nano-hydroxyapatite/poly(L-lactic acid) (nano-HA/PLLA) spindle composites with good mechanical performance were fabricated by a modified in situ precipitation method. The HA part of composite, distributing homogenously in PLLA matrix, is spindle shape with size of 10-30 nm in diameter and 60-100 nm in length. The molar ratio of Ca/P in the synthesized nano-HA spindles was deduced as 1.52 from the EDS spectra, which is close to the stoichiometric composition of HA (Ca/P & 1.67). The compress strength is up to 150 MPa when the HA content increase to 20 %. The in vitro tests indicate that HA/PLLA bio-composites have good biodegradability and bioactivity when immersed in simulated body fluid solutions. All the results suggested that HA/PLLA nano-biocomposites are appropriate to be applied as bone substitute in bone tissue engineering. PMID:27379628

  8. Mechanical properties' improvement of a tricalcium phosphate scaffold with poly-l-lactic acid in selective laser sintering.

    PubMed

    Liu, Defu; Zhuang, Jingyu; Shuai, Cijun; Peng, Shuping

    2013-06-01

    To improve the mechanical properties of a scaffold fabricated via selective laser sintering (SLS), a small amount (0.5-3 wt%) of poly-l-lactic acid (PLLA) is added to the β-tricalcium phosphate (β-TCP) powder. The fracture toughness of the scaffold prepared with the mixture powder containing 1 wt% PLLA increases by 18.18% and the compressive strength increases by 4.45% compared to the scaffold prepared from the β-TCP powder. The strengthening and toughening is related to the enhancement of β-TCP sintering characteristics via introducing a transient liquid phase in SLS. Moreover, the microcracks caused by the volume expansion due to the β-α phase transformation of TCP are reduced because of the PLLA inhibition function on the phase transformation. However, PLLA additive above 1 wt% would lead to a PLLA residue which will decrease the mechanical properties. The experimental results show that PLLA is an effective sintering aid to improve the mechanical properties of a TCP scaffold. PMID:23458914

  9. Influence of poly-L-lactic acid scaffold's pore size on the proliferation and differentiation of dental pulp stem cells.

    PubMed

    Conde, Cristian Muniz; Demarco, Flávio Fernando; Casagrande, Luciano; Alcazar, José Carlos; Nör, Jacques Eduardo; Tarquinio, Sandra Beatriz Chaves

    2015-01-01

    The aim of this study was to evaluate the influence of the poly-L-lactic acid (PLLA)-based scaffold's pore size on the proliferation and differentiation of dental pulp stem cells (DPSCs). The scaffolds were prepared in pulp chambers of 1-mm-thick tooth slices from third molars using salt crystals (150-250 µm or 251-450 µm) as porogen. DPSC (1x105 cells) were seeded in the scaffolds with different pore sizes, and cultured in 24-well plates. The cell proliferation was evaluated using the WST-1 assay after 3-21 days. Furthermore, RT-PCR was used to assess the differentiation of the DPSCs into odontoblasts, using markers of odontoblastic differentiation (DSPP, DSP-1 and MEPE). RNA from human odontoblasts was used as control. Cell proliferation rate was similar in both scaffolds except at the 14th day period, in which the cells seeded in the scaffolds with larger pores showed higher proliferation (p<0.05). After 21 days DPSCs seeded in both evaluated scaffolds were able of expressing odontoblastic markers DMP-1, DSPP and MEPE. In summary, both scaffolds tested in this study allowed the proliferation and differentiation of DPSCs into odontoblast-like cells. PMID:25831096

  10. Optimizing injectable poly-L-lactic acid administration for soft tissue augmentation: The rationale for three treatment sessions

    PubMed Central

    Bauer, Ute; Graivier, Miles H

    2011-01-01

    BACKGROUND: The availability and variety of different injectable modalities has led to a dramatic increase in soft tissue augmentation procedures in recent years. Injectable poly-L-lactic acid (PLLA) is a synthetic, biodegradable polymer device approved in the United States for use in immunocompetent patients as a single regimen of up to four treatment sessions for correction of shallow to deep nasolabial fold contour deficiencies and other facial wrinkles. Injectable PLLA is also approved for restoration and/or correction of signs of facial fat loss (lipoatrophy) in individuals with HIV. METHODS: The present article provides an overview of previous studies with injectable PLLA, and specifically focuses on the number of recommended treatment sessions and intervals between treatment sessions. The authors also provide two case studies to support their recommendations for an average of three treatment sessions. RESULTS: Although the specific mechanisms remain hypothetical, injections of PLLA are believed to cause a cascade of cellular events that lead to collagen repair and subsequent restoration of facial volume. Because the development of a response to injectable PLLA is gradual and its duration of effect is long lasting, sufficient time between treatment sessions should be allocated to avoid overcorrection. CONCLUSION: Studies of injectable PLLA support the hypothesized mode of operation, and the experience and clinical recommendations of the authors that suggest that three treatment sessions are an optimal regimen for use of injectable PLLA in the majority of patients. PMID:22942665

  11. Quantitative XPS depth profiling of codeine loaded poly(l-lactic acid) films using a coronene ion sputter source.

    PubMed

    Rafati, Ali; Davies, Martyn C; Shard, Alexander G; Hutton, Simon; Mishra, Gautam; Alexander, Morgan R

    2009-08-19

    The controlled release of active pharmaceutical ingredients from polymers over prolonged periods of time is vital for the function of drug eluting stents and other drug loaded delivery devices. Characterisation of the drug distribution in polymers allows the in vitro and in vivo performance to be rationalised. We present the first X-ray photoelectron spectroscopy (XPS) depth profiling study of such a drug eluting stent system for which we employ a novel coronene ion sputter source. The rationale for this is to ascertain quantitative atomic concentration data through the thickness of flat films containing codeine and poly(l-lactic acid) (PLA) as a model of a drug loaded polymer device. A range of films of thickness of up to 96 nm are spun cast from chloroform onto Piranha cleaned silicon wafers. Ellipsometry of the films is undertaken prior to depth profiling to determine the total film thickness and provide a measure of the relative loading of drug within the PLA matrix through spectroscopic analysis. Progressive XPS analysis of the bottom of the sputter crater with sputter time indicated codeine to be depleted from the surface and segregated to the bulk of the polymer films by comparison with a uniform distribution calculated from the bulk loading. This serves to illustrate that surface depletion of drug occurs, which poses important implications for drug loaded polymer delivery systems. PMID:19427343

  12. Hydroxyapatite (HA)/poly-L-lactic acid (PLLA) dual coating on magnesium alloy under deformation for biomedical applications.

    PubMed

    Diez, Mathilde; Kang, Min-Ho; Kim, Sae-Mi; Kim, Hyoun-Ee; Song, Juha

    2016-02-01

    The introduction of a protective coating layer to highly corrosive magnesium (Mg) has been proposed as one of the common approaches for improved corrosion resistance of Mg-based implants as load-bearing biomedical applications. However, only few studies have focused on the mechanical stability of the coated Mg under practical conditions where significant deformation of the load-bearing implants is induced during the surgical operation or under physiological environments. Therefore, in this study, we developed a dual coating system composed of an interlayer hydroxyapatite (HA) and a top layer poly-L-lactic acid (PLLA) to improve the coating stability under deformation of Mg alloy (WE43) substrate. The HA interlayer was directly formed on the Mg alloy surface, followed by dip-coating of PLLA. As the interlayer, HA improved the adhesion of PLLA by modulating nano- and microscale roughness, in addition to its inherently good bonding strength to Mg. The flexible and deformable top coating PLLA layer mitigated crack propagation in the HA layer under deformation. Thus, the dual coating layer provided good protection to the underlying WE43 from corrosion regardless of deformation. The enhanced corrosion behavior of dual-coated WE43 exhibited better mechanical and biological performance compared to the non-coated or single-coated WE43. Therefore, this dual coating layer on Mg is expected to accelerate Mg-based applications in biomedical devices. PMID:26704551

  13. Superhydrophilic poly(L-lactic acid) electrospun membranes for biomedical applications obtained by argon and oxygen plasma treatment

    NASA Astrophysics Data System (ADS)

    Correia, D. M.; Ribeiro, C.; Botelho, G.; Borges, J.; Lopes, C.; Vaz, F.; Carabineiro, S. A. C.; Machado, A. V.; Lanceros-Méndez, S.

    2016-05-01

    Poly(L-lactic acid), PLLA, electrospun membranes and films were plasma treated at different times and power with argon (Ar) and oxygen (O2), independently, in order to modify the hydrophobic nature of the PLLA membranes. Both Ar and O2 plasma treatments promote an increase in fiber average size of the electrospun membranes from 830 ± 282 nm to 866 ± 361 and 1179 ± 397 nm, respectively, for the maximum exposure time (970 s) and power (100 W). No influence of plasma treatment was detected in the physical-chemical characteristics of PLLA, such as chemical structure, polymer phase or degree of crystallinity. On the other hand, an increase in the roughness of the films was obtained both with argon and oxygen plasma treatments. Surface wettability studies revealed a decrease in the contact angle with increasing plasma treatment time for a given power and with increasing power for a given time in membranes and films and superhydrophilic electrospun fiber membranes were obtained. Results showed that the argon and oxygen plasma treatments can be used to tailor hydrophilicity of PLLA membranes for biomedical applications. MTT assay results indicated that plasma treatments under Ar and O2 do not influence the metabolic activity of MC3T3-E1 pre-osteoblast cells.

  14. Mineralization and drug release of hydroxyapatite/poly(l-lactic acid) nanocomposite scaffolds prepared by Pickering emulsion templating.

    PubMed

    Hu, Yang; Zou, Shengwen; Chen, Weike; Tong, Zhen; Wang, Chaoyang

    2014-10-01

    Biodegradable and bioactive nanocomposite (NC) biomaterials with controlled microstructures and able to deliver special drugs have gained increasing attention in bone tissue engineering. In this study, the hydroxyapatite (HAp)/poly(l-lactic acid) (PLLA) NC scaffolds were facilely prepared using solvent evaporation from templating Pickering emulsions stabilized with PLLA-modified HAp (g-HAp) nanoparticles. Then, in vitro mineralization experiments were performed in a simulated body fluid (SBF) to evaluate the bioactivity of the NC scaffolds. Moreover, in vitro drug release of the NC scaffolds using anti-inflammatory drug (ibuprofen, IBU) as the model drug was also investigated. The results showed that the NC scaffolds possessed interconnected pore structures, which could be modulated by varying the g-HAp nanoparticle concentration. The NC scaffolds exhibited excellent bioactivity, since they induced the formation of calcium-sufficient, carbonated apatite nanoparticles on the scaffolds after mineralization in SBF for 3 days. The IBU loaded in the NC scaffolds showed a sustained release profile, and the release kinetic followed the Higuchi model with diffusion process. Thus, solvent evaporation based on Pickering emulsion droplets is a simple and effective method to prepare biodegradable and bioactive porous NC scaffolds for bone repair and replacement applications. PMID:25127362

  15. Enhanced bone formation in electrospun poly(L-lactic-co-glycolic acid)-tussah silk fibroin ultrafine nanofiber scaffolds incorporated with graphene oxide.

    PubMed

    Shao, Weili; He, Jianxin; Sang, Feng; Wang, Qian; Chen, Li; Cui, Shizhong; Ding, Bin

    2016-05-01

    To engineer bone tissue, it is necessary to provide a biocompatible, mechanically robust scaffold. In this study, we fabricated an ultrafine nanofiber scaffold by electrospinning a blend of poly(L-lactic-co-glycolic acid), tussah silk fibroin, and graphene oxide (GO) and characterized its morphology, biocompatibility, mechanical properties, and biological activity. The data indicate that incorporation of 10 wt.% tussah silk and 1 wt.% graphene oxide into poly(L-lactic-co-glycolic acid) nanofibers significantly decreased the fiber diameter from 280 to 130 nm. Furthermore, tussah silk and graphene oxide boosted the Young's modulus and tensile strength by nearly 4-fold and 3-fold, respectively, and significantly enhanced adhesion, proliferation in mouse mesenchymal stem cells and functionally promoted biomineralization-relevant alkaline phosphatase (ALP) and mineral deposition. The results indicate that composite nanofibers could be excellent and versatile scaffolds for bone tissue engineering. PMID:26952489

  16. Review and Evaluation of Treatment Procedures Using Injectable Poly-L-Lactic Acid in the Treatment of Human Immunodeficiency Virus–associated Facial Lipoatrophy

    PubMed Central

    Humble, Gail

    2010-01-01

    Injectable poly-L-lactic acid is United States Food and Drug Administration–approved for the restoration and/or correction of the signs of lipoatrophy in people with human immunodeficiency virus and for use in immune-competent people for the correction of nasolabial fold contour deficiencies. Current prescribing information recommends using either a tunneling or threading technique in a grid or cross-hatched pattern or a depot technique (in thin skin areas) to administer multiple passes of injectable poly-L-lactic acid per treatment session via a 26-gauge needle. A review of the literature and the recently published guidelines from the American Society for Dermatologic Surgery provide evidence to support the use of a cross-fanning technique with a 25-gauge needle. In conclusion, the use of a cross-fanning injection technique with a 25-gauge needle to administer injectable poly-L-lactic acid provides a clinically valid, alternate delivery option for the treatment of patients with human immunodeficiency virus-associated lipoatrophy. PMID:21203355

  17. Molecular biocompatibility evaluation of poly(D,L-lactic acid)-modified biomaterials based on long serial analysis of gene expression.

    PubMed

    Xiang, Yan; Wang, Yuanliang; Luo, Yanfeng; Zhang, Bingbing; Xin, Juan; Zheng, Danfang

    2011-07-01

    In this work, long serial analysis of gene expression (LongSAGE) technology was used to investigate the molecular mechanism of the interaction between cells and poly(D,L-lactic acid)-modified biomaterials. After mouse osteoblast-like MC3T3-E1 cells were cultured on poly(D,L-lactic acid) (PDLLA) and a novel maleic anhydride-modified poly(D,L-lactic acid) (MPLA) films, the morphology, proliferation activity and alkaline phosphatase (ALP) activity of MC3T3-E1 cells were assessed by laser confocal microscope, cell counting assay and ALP assay, and the gene expression profiles of the cells were detected and compared at the transcript levels, respectively. 202 tags were found differentially expressed (p<0.05, and fold change >2) between PDLLA and MPLA LongSAGE libraries. Gene ontology functional analysis of the differentially expressed genes indicates that surface modification of MPLA biomaterial has an extensive influence on cells by regulating expression of genes related to cell proliferation, cell cycle, cytoskeleton organization, ossification, bone remodeling, metabolism, and eventually induces osteoblast proliferation and differentiation. The approach presented here provides a new insight in the molecular biocompatibility evaluation of biomaterials, contributing to the development of biomaterials in tissue engineering field. PMID:21435849

  18. Thermo-mechanical properties of poly ε-caprolactone/poly L-lactic acid blends: addition of nalidixic acid and polyethylene glycol additives.

    PubMed

    Douglas, P; Albadarin, Ahmad B; Al-Muhtaseb, Ala'a H; Mangwandi, Chirangano; Walker, G M

    2015-05-01

    The search for ideal biomaterials is still on-going for tissue regeneration. In this study, blends of poly ε-caprolactone (PCL) with poly l-lactic acid (PLLA), nalidixic acid (NA) and polyethylene glycol (PEG) were prepared. Mechanical and thermal properties of the blends were investigated by tensile and flexural analysis, DSC, TGA, WXRD, MFI, BET, SEM and hot stage optical microscopy. Results showed that the loading of PLLA caused a significant decrease in tensile strength and almost total eradication of the elongation at break of PCL matrix, especially after PEG and NA addition. Increased stiffness was also noted with additional NA, PEG and PLLA, resulting in an increase in the flexural modulus of the blends. Isothermal degradation indicated that bulk PCL, PLLA and the blends were thermally stable at 200°C for the duration of 2h making extrusion of the blends at this temperature viable. Morphological study showed that increasing the PLLA content and addition of the very low viscosity PEG and powder NA decreased the Melt Flow Indexer and increased the viscosity. At the higher temperature, the PLLA begins to soften and eventually melts allowing for increased flow and, coupling this with, the natural increase in MFI caused by temperature is enhanced further. The PEG and NA addition increased dramatically the pore volume which is important for cell growth and flow transport of nutrients and metabolic waste. PMID:25725403

  19. The Structure of Hydrated Poly (D, L - Lactic Acid) Studied With X-Ray Diffraction and Molecular Simulation Methods

    PubMed Central

    Li, Xianfeng; Murthy, N. Sanjeeva; Latour, Robert A.

    2012-01-01

    The effect of hydration on the molecular structure of amorphous poly (D, L-lactic acid) (PDLLA) with 50:50 L-to-D ratio has been studied by combining experiments with molecular simulations. X-ray diffraction measurements revealed significant changes upon hydration in the structure functions of the copolymer. Large changes in the structure functions at ~ 10 days of incubation coincided with the large increase in the water uptake from ~1 to ~40% and the formation of voids in the film. Computer modeling based on the recently developed TIGER2/TIGER3 mixed sampling scheme was used to interpret these changes by efficiently equilibrating both dry and hydrated models of PDLLA. Realistic models of bulk amorphous PDLLA structure were generated as demonstrated by close agreement between the calculated and the experimental structure functions. These molecular simulations were used to identify the interactions between water and the polymer at the atomic level including the change of positional order between atoms in the polymer due to hydration. Changes in the partial O-O structure functions, about 95% of which were due to water-polymer interactions, were apparent in the radial distribution functions. These changes, and somewhat smaller changes in the C-C and C-O partial structure functions, clearly demonstrated the ability of the model to capture the hydrogen bonding interactions between water and the polymer, with the probability of water forming hydrogen bonds with the carbonyl oxygen of the ester group being about four times higher than with its ether oxygen. PMID:22707795

  20. Gum tragacanth/poly(l-lactic acid) nanofibrous scaffolds for application in regeneration of peripheral nerve damage.

    PubMed

    Ranjbar-Mohammadi, Marziyeh; Prabhakaran, Molamma P; Bahrami, S Hajir; Ramakrishna, Seeram

    2016-04-20

    Nanofibrous nerve guides have gained huge interest in supporting the peripheral nerve regeneration due to their abilities to simulate the topography, mechanical, biological and extracellular matrix morphology of native tissue. Gum tragacanth (GT) is a biocompatible mixture of polysaccharides that has been used in biomedical applications. During this study, we fabricated aligned and random nanofibers from poly(l-lactic acid) and gum tragacanth (PLLA/GT) in various ratios (100:0, 75:25, and 50:50) by electrospinning. Scanning electron microscope demonstrated smooth and uniform nanofibers with diameters in the range of 733±65nm and 226±73nm for align PLLA and random PLLA/GT 50:50 nanofibers, respectively. FTIR analysis, contact angle, in vitro biodegradation and tensile measurements were carried out to evaluate the chemical and mechanical properties of the different scaffolds. PLLA/GT 75:25 exhibited the most balanced properties compared to other scaffolds and was used for in vitro culture of nerve cells (PC12) to assess the potential of using these scaffolds as a substrate for nerve regeneration. The cells were found to attach and proliferate on aligned PLLA/GT 75:25 scaffolds, expressing bi-polar neurite extensions and the orientation of nerve cells was along the direction of the fiber alignment. Results of 8 days of in vitro culture of PC12 cells on aligned PLLA/GT 75:25 nanofibers, showed 20% increase in cell proliferation compared to PLLA/GT 75:25 random nanofibers. PLLA/GT 75:25 aligned nanofibers acted as a favorable cue to support neurite outgrowth and nerve cell elongation compared with PLLA nanofibers. Our results showed that aligned PLLA/GT 75:25 nanofibers are promising substrates for application as bioengineered grafts for nerve tissue regeneration. PMID:26876833

  1. Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

    NASA Astrophysics Data System (ADS)

    Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju; Kim, Hye-Lee; Jin Lee, Seung; Kim, Bong-Jin; Wang, Kang-Kyun; Kim, Yong-Rok; Park, Jong-Chul

    2013-08-01

    Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH2 (399.70 eV) was increased significantly and -N=CH (400.80 eV) and -NH3+ (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

  2. The Effect of Surface Modification of Aligned Poly-L-Lactic Acid Electrospun Fibers on Fiber Degradation and Neurite Extension

    PubMed Central

    Schaub, Nicholas J.; Le Beux, Clémentine; Miao, Jianjun; Linhardt, Robert J.; Alauzun, Johan G.; Laurencin, Danielle; Gilbert, Ryan J.

    2015-01-01

    The surface of aligned, electrospun poly-L-lactic acid (PLLA) fibers was chemically modified to determine if surface chemistry and hydrophilicity could improve neurite extension from chick dorsal root ganglia. Specifically, diethylenetriamine (DTA, for amine functionalization), 2-(2-aminoethoxy)ethanol (AEO, for alcohol functionalization), or GRGDS (cell adhesion peptide) were covalently attached to the surface of electrospun fibers. Water contact angle measurements revealed that surface modification of electrospun fibers significantly improved fiber hydrophilicity compared to unmodified fibers (p < 0.05). Scanning electron microscopy (SEM) of fibers revealed that surface modification changed fiber topography modestly, with DTA modified fibers displaying the roughest surface structure. Degradation of chemically modified fibers revealed no change in fiber diameter in any group over a period of seven days. Unexpectedly, neurites from chick DRG were longest on fibers without surface modification (1651 ± 488 μm) and fibers containing GRGDS (1560 ± 107 μm). Fibers modified with oxygen plasma (1240 ± 143 μm) or DTA (1118 ± 82 μm) produced shorter neurites than the GRGDS or unmodified fibers, but were not statistically shorter than unmodified and GRGDS modified fibers. Fibers modified with AEO (844 ± 151 μm) were significantly shorter than unmodified and GRGDS modified fibers (p<0.05). Based on these results, we conclude that fiber hydrophilic enhancement alone on electrospun PLLA fibers does not enhance neurite outgrowth. Further work must be conducted to better understand why neurite extension was not improved on more hydrophilic fibers, but the results presented here do not recommend hydrophilic surface modification for the purpose of improving neurite extension unless a bioactive ligand is used. PMID:26340351

  3. Application of layered poly (L-lactic acid) cell free scaffold in a rabbit rotator cuff defect model

    PubMed Central

    2011-01-01

    Background This study evaluated the application of a layered cell free poly (L-lactic acid) (PLLA) scaffold to regenerate an infraspinatus tendon defect in a rabbit model. We hypothesized that PLLA scaffold without cultivated cells would lead to regeneration of tissue with mechanical properties similar to reattached infraspinatus without tendon defects. Methods Layered PLLA fabric with a smooth surface on one side and a pile-finished surface on the other side was used. Novel form of layered PLLA scaffold was created by superimposing 2 PLLA fabrics. Defects of the infraspinatus tendon were created in 32 rabbits and the PLLA scaffolds were transplanted, four rabbits were used as normal control. Contralateral infraspinatus tendons were reattached to humeral head without scaffold implantation. Histological and mechanical evaluations were performed at 4, 8, and 16 weeks after operation. Results At 4 weeks postoperatively, cell migration was observed in the interstice of the PLLA fibers. Regenerated tissue was directly connected to the bone composed mainly of type III collagen, at 16 weeks postoperatively. The ultimate failure load increased in a time-dependent manner and no statistical difference was seen between normal infraspinatus tendon and scaffold group at 8 and 16 weeks postoperatively. There were no differences between scaffold group and reattach group at each time of point. The stiffness did not improve significantly in both groups. Conclusions A novel form of layered PLLA scaffold has the potential to induce cell migration into the scaffold and to bridge the tendon defect with mechanical properties similar to reattached infraspinatus tendon model. PMID:22136125

  4. Preparation of Porous Core-Shell Poly L-Lactic Acid/Polyethylene Glycol Superfine Fibres Containing Drug.

    PubMed

    Yang, Wenjing; He, Nongyue; Fu, Juan; Li, Zhiyang; Ji, Xuyuan

    2015-12-01

    In this paper, poly L-lactic acid (PLLA) blended with polyethylene glycol (PEG) was dissolved in methylene dichloride solution as the shell solution, and rapamycin (RAPA), was encapsulated inside the core of PLLA micro/nano fibres as a model drug. The effects of the blending ratio of PLLA to PEG, the concentration of the electrospinning solution, the voltage, the flow rate, and the encapsulation efficiency were studied. Uniform and porous RAPA-Loading PLLA fibres were obtained when the ratio of PLLA to PEG was 7/3, the concentration of PLLA was 3%, the applied voltage was 7.5 kV, and the pump speed was V(core) = 0.1 mL/h, V(shell) = 1 mL/h, repectively. The average diameter of PLLA fibres increased with the gradual increase in PLLA concentration. FTIR results showed that RAPA was successfully encapsulated into the core-co-shell PLLA fibres. Meanwhile, the RAPA-loading of coaxial electrospun PLLA fibres was significantly higher than that of the blending electrospun fibres. It was also found that the porous core-shell PLLA/PEG blending superfine fibres could regulate the appearance of pore on the surface of superfine fibres by adjusting the electrospinning parameters. The porous PLLA/PEG blending fibres can be used as drug carriers and, to improve the single way of drug release depending on the degradation of shell material to meet different need. It will be a remarkable breakthrough in the area for sustained and controlled release drug delivery system. PMID:26682434

  5. Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

    SciTech Connect

    Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju; Kim, Hye-Lee; Park, Jong-Chul; Jin Lee, Seung; Kim, Bong-Jin; Wang, Kang-Kyun; Kim, Yong-Rok

    2013-08-21

    Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH{sub 2} (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH{sub 3}{sup +} (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

  6. Structure of Hydrated Poly(d,l-lactic acid) Studied with X-ray Diffraction and Molecular Simulation Methods

    SciTech Connect

    Li, Xianfeng; Murthy, N. Sanjeeva; Latour, Robert A.

    2012-10-10

    The effect of hydration on the molecular structure of amorphous poly(D,L-lactic acid) (PDLLA) with 50:50 L-to-D ratio has been studied by combining experiments with molecular simulations. X-ray diffraction measurements revealed significant changes upon hydration in the structure functions of the copolymer. Large changes in the structure functions at 10 days of incubation coincided with the large increase in the water uptake from {approx} 1 to {approx} 40% and the formation of voids in the film. Computer modeling based on the recently developed TIGER2/TIGER3 mixed sampling scheme was used to interpret these changes by efficiently equilibrating both dry and hydrated models of PDLLA. Realistic models of bulk amorphous PDLLA structure were generated as demonstrated by close agreement between the calculated and the experimental structure functions. These molecular simulations were used to identify the interactions between water and the polymer at the atomic level including the change of positional order between atoms in the polymer due to hydration. Changes in the partial O-O structure functions, about 95% of which were due to water-polymer interactions, were apparent in the radial distribution functions. These changes, and somewhat smaller changes in the C-C and C-O partial structure functions, clearly demonstrated the ability of the model to capture the hydrogen-bonding interactions between water and the polymer, with the probability of water forming hydrogen bonds with the carbonyl oxygen of the ester group being about 4 times higher than with its ether oxygen.

  7. Well-organized neointima of large-pore poly(l-lactic acid) vascular graft coated with poly(l-lactic-co-ε-caprolactone) prevents calcific deposition compared to small-pore electrospun poly(l-lactic acid) graft in a mouse aortic implantation model

    PubMed Central

    Tara, Shuhei; Kurobe, Hirotsugu; Rocco, Kevin A.; Maxfield, Mark W.; Best, Cameron A.; Yi, Tai; Naito, Yuji; Breuer, Christopher K.; Shinoka, Toshiharu

    2014-01-01

    Objective Tissue engineering techniques have emerged that allow bioresorbable grafts to be implanted that restore function and transform into biologically active arteries. However, these implants are susceptible to calcification during the remodeling process. The objective of this study was to evaluate the role of pore size of bioabsorbable grafts in the development of calcification. Methods Two types of grafts were prepared: a large-pore graft constructed of poly(l-lactic acid) (PLA) fibers coated with poly(l-lactide-co-ε-caprolactone) (PLCL) (PLA-PLCL), and a small-pore graft made of electrospun PLA nanofibers (PLA-nano). Twenty-eight PLA-PLCL grafts and twenty-five PLA-nano grafts were implanted as infra-renal aortic interposition conduits in 8-week-old female SCID/Bg mice, and followed for 12 months after implantation. Results Large-pore PLA-PLCL grafts induced a well-organized neointima after 12 months, and Alizarin Red S staining showed neointimal calcification only in the thin neointima of small-pore PLA-nano grafts. At 12 months, macrophage infiltration, evaluated by F4/80 staining, was observed in the thin neointima of the PLA-nano graft, and there were few vascular smooth muscle cells (VSMCs) in this layer. On the other hand, the neointima of the PLA-PLCL graft was composed of abundant VSMCs, and a lower density of macrophages (F4/80 positive cells, PLA-PLCL; 68.1±41.4/mm2 vs PLA-nano; 188.3±41.9/mm2, p = 0.007). The VSMCs of PLA-PLCL graft expressed transcription factors of both osteoblasts and osteoclasts. Conclusion These findings demonstrate that in mouse arterial circulation, large-pore PLA-PLCL grafts created a well-organized neointima and prevented calcific deposition compared to small-pore, electrospun PLA-nano grafts. PMID:25463106

  8. Morphological effects of porous poly-d,l-lactic acid/hydroxyapatite scaffolds produced by supercritical CO2 foaming on their mechanical performance.

    PubMed

    Rouholamin, Davood; van Grunsven, William; Reilly, Gwendolen C; Smith, Patrick J

    2016-08-01

    A novel supercritical CO2 foaming technique was used to fabricate scaffolds of controllable morphology and mechanical properties, with the potential to tailor the scaffolds to specific tissue engineering applications. Biodegradable scaffolds are widely used as temporary supportive structures for bone regeneration. The scaffolds must provide a sufficient mechanical support while allowing cell attachment and growth as well as metabolic activities. In this study, supercritical CO2 foaming was used to prepare fully interconnected porous scaffolds of poly-d,l-lactic acid and poly-d,l-lactic acid/hydroxyapatite. The morphological, mechanical and cell behaviours of the scaffolds were measured to examine the effect of hydroxyapatite on these properties. These scaffolds showed an average porosity in the range of 86%-95%, an average pore diameter of 229-347 µm and an average pore interconnection of 103-207 µm. The measured porosity, pore diameter, and interconnection size are suitable for cancellous bone regeneration. Compressive strength and modulus of up to 36.03 ± 5.90 and 37.97 ± 6.84 MPa were measured for the produced porous scaffolds of various compositions. The mechanical properties presented an improvement with the addition of hydroxyapatite to the structure. The relationship between morphological and mechanical properties was investigated. The matrices with different compositions were seeded with bone cells, and all the matrices showed a high cell viability and biocompatibility. The number of cells attached on the matrices slightly increased with the addition of hydroxyapatite indicating that hydroxyapatite improves the biocompatibility and proliferation of the scaffolds. The produced poly-d,l-lactic acid/hydroxyapatite scaffolds in this study showed a potential to be used as bone graft substitutes. PMID:27226064

  9. Biomimetic scaffolds based on hydroxyapatite nanorod/poly(D,L) lactic acid with their corresponding apatite-forming capability and biocompatibility for bone-tissue engineering.

    PubMed

    Nga, Nguyen Kim; Hoai, Tran Thanh; Viet, Pham Hung

    2015-04-01

    This study presents a facile synthesis of biomimetic hydroxyapatite nanorod/poly(D,L) lactic acid (HAp/PDLLA) scaffolds with the use of solvent casting combined with a salt-leaching technique for bone-tissue engineering. Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy were used to observe the morphologies, pore structures of synthesized scaffolds, interactions between hydroxyapatite nanorods and poly(D,L) lactic acid, as well as the compositions of the scaffolds, respectively. Porosity of the scaffolds was determined using the liquid substitution method. Moreover, the apatite-forming capability of the scaffolds was evaluated through simulated body fluid (SBF) incubation tests, whereas the viability, attachment, and distribution of human osteoblast cells (MG 63 cell line) on the scaffolds were determined through alamarBlue assay and confocal laser microscopy after nuclear staining with 4',6-diamidino-2-phenylindole and actin filaments of a cytoskeleton with Oregon Green 488 phalloidin. Results showed that hydroxyapatite nanorod/poly(D,L) lactic acid scaffolds that mimic the structure of natural bone were successfully produced. These scaffolds possessed macropore networks with high porosity (80-84%) and mean pore sizes ranging 117-183 μm. These scaffolds demonstrated excellent apatite-forming capabilities. The rapid formation of bone-like apatites with flower-like morphology was observed after 7 days of incubation in SBFs. The scaffolds that had a high percentage (30 wt.%) of hydroxyapatite demonstrated better cell adhesion, proliferation, and distribution than those with low percentages of hydroxyapatite as the days of culture increased. This work presented an efficient route for developing biomimetic composite scaffolds, which have potential applications in bone-tissue engineering. PMID:25791418

  10. Fabrication and characterization of modified nanofibrous poly(L-lactic acid) scaffolds by thermally induced phase separation technique and aminolysis for promoting cyctocompatibility.

    PubMed

    Chen, Shunyu; He, Zhihang; Xu, Guojie; Xiao, Xiufeng

    2016-07-01

    Modified nanofibrous Poly(L-lactic acid) (PLLA) scaffolds were fabricated by aminolysis combined with thermally induced phase separation technique using PLLA/1,4-dioxane/urea-NaOH-H2O system at -40 °C freeze temperature. Aminolysis led to the modification of scaffold resulting in enhancement in the bioactivity. The surface of the modified nanofibrous scaffold provided a good environment for attachment and proliferation of MC3T3-E1 subclone 14 cells, exhibiting significant potential for bone tissue regeneration and for promoting cytocompatibility. PMID:27095503

  11. Improved biocompatibility of poly(lactic-co-glycolic acid) orv and poly-L-lactic acid blended with nanoparticulate amorphous calcium phosphate in vascular stent applications.

    PubMed

    Zheng, Xiaoxin; Wang, Yujue; Lan, Zhiyuan; Lyu, Yongnan; Feng, Gaoke; Zhang, Yipei; Tagusari, Shizu; Kislauskis, Edward; Robich, Michael P; McCarthy, Stephen; Sellke, Frank W; Laham, Roger; Jiang, Xuejun; Gu, Wei Wang; Wu, Tim

    2014-06-01

    Biodegradable polymers used as vascular stent coatings and stent platforms encounter a major challenge: biocompatibility in vivo, which plays an important role in in-stent restenosis (ISR). Co-formulating amorphous calcium phosphate (ACP) into poly(lactic-co-glycolic acid) (PLGA) or poly-L-lactic acid (PLLA) was investigated to address the issue. For stent coating applications, metal stents were coated with polyethylene-co-vinyl acetate/poly-n-butyl methacrylate (PEVA/PBMA), PLGA or PLGA/ACP composites, and implanted into rat aortas for one and three months. Comparing with both PEVA/PBMA and PLGA groups after one month, the results showed that stents coated with PLGA/ACP had significantly reduced restenosis (PLGA/ACP vs. PEVA/PBMA vs. PLGA: 21.24 +/- 2.59% vs. 27.54 +/- 1.19% vs. 32.12 +/- 3.93%, P < 0.05), reduced inflammation (1.25 +/- 0.35 vs. 1.77 +/- 0.38 vs. 2.30 +/- 0.21, P < 0.05) and increased speed of re-endothelialization (1.78 +/- 0.46 vs. 1.17 +/- 0.18 vs. 1.20 +/- 0.18, P < 0.05). After three months, the PLGA/ACP group still displayed lower inflammation score (1.33 +/- 0.33 vs. 2.27 +/- 0.55, P < 0.05) and higher endothelial scores (2.33 +/- 0.33 vs. 1.20 +/- 0.18, P < 0.05) as compared with the PEVA/PBMA group. Moreover, for stent platform applications, PLLA/ACP stent tube significantly reduced the inflammatory cells infiltration in the vessel walls of rabbit iliac arteries relative to their PLLA cohort (NF-kappaB-positive cells: 23.31 +/- 2.33/mm2 vs. 9.34 +/- 1.35/mm2, P < 0.05). No systemic biochemical or pathological evidence of toxicity was found in either PLGA/ACP or PLLA/ACP. The co-formulation of ACP into PLGA and PLLA resulted in improved biocompatibility without systemic toxicity. PMID:24749387

  12. An electrically conductive 3D scaffold based on a nonwoven web of poly(L-lactic acid) and conductive poly(3,4-ethylenedioxythiophene).

    PubMed

    Niu, Xufeng; Rouabhia, Mahmoud; Chiffot, Nicolas; King, Martin W; Zhang, Ze

    2015-08-01

    This study was to demonstrate that an extremely thin coating of poly(3,4-ethylenedioxythiophene) (PEDOT) on nonwoven microfibrous poly(l-lactic acid) (PLLA) web is of sufficient electrical conductivity and stability in aqueous environment to sustain electrical stimulation (ES) to cultured human skin fibroblasts. The PEDOT imparted the web a surface resistivity of approximately 0.1 KΩ/square without altering the web morphology. X-ray photoelectron spectroscopy demonstrated that the surface chemistry of the PLLA/PEDOT is characteristic of both PLLA and PEDOT. The PEDOT-coated web also showed higher hydrophilicity, lower glass transition temperature and unchanged fiber crystallinity and thermal stability compared with the PLLA web. The addition of PEDOT to the web marginally increased the web's tensile strength and lowered the elongation. An electrical stability test showed that the PLLA/PEDOT structure was more stable than a polypyrrole treated PLLA fabric, showing only a slow deterioration in conductivity when exposed to culture medium. The cytotoxicity test showed that the PLLA/PEDOT scaffold was not cytotoxic and supported human dermal fibroblast adhesion, migration, and proliferation. Preliminary ES experiments have demonstrated that this conductive web mediated effective ES to fibroblasts. Therefore, this new conductive biodegradable scaffold may be used to electrically modulate cellular activity and tissue regeneration. PMID:25630631

  13. Conformationally disordered crystals and their influence on material properties: The cases of isotactic polypropylene, isotactic poly(1-butene), and poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Cocca, Mariacristina; Androsch, René; Righetti, Maria Cristina; Malinconico, Mario; Di Lorenzo, Maria Laura

    2014-12-01

    This article provides a comprehensive review of the physical properties of the conformationally disordered (condis) structures of isotactic polypropylene (iPP), isotactic poly(1-butene) (iPB-1) and poly(L-lactic acid) (PLLA), in comparison with the respective more stable crystalline forms. The aim of this review is to define the influence of the condis modifications on the thermal and mechanical properties of these materials. The condis structures of the three polymers are metastable and spontaneously transform into the more stable crystalline structures upon annealing above a critical temperature. The transition from the mesophase to the more stable crystalline structure becomes possible when the chains have sufficient mobility to allow rearrangements of chain conformations. A rigid amorphous fraction develops during solidification of iPP, iPB-1 and PLLA. Crystallization of iPB-1 and PLLA into the more stable forms leads to a larger coupling of the amorphous and crystalline chain segments, compared to the conformationally disordered arrangements, which results in a higher fraction of rigid amorphous chain segments. The difference in chain packing, together with the varied mobility of the coupled amorphous chain portions, affects both the initial resistance to the tensile strain and the large strain properties. All the three stable crystalline forms have a higher Young's modulus compared to the condis mesophases, and can sustain lower deformation under mechanical stimuli.

  14. Synthesis of HAP nano rods and processing of nano-size ceramic reinforced poly(L)lactic acid composites

    NASA Astrophysics Data System (ADS)

    Flanigan, Kyle Yusef

    2000-09-01

    Bone is unique among the various connective tissues in that it is a composite of organic and inorganic components. Calcium phosphates occur principally in the form of hydroxyapatite crystals {Ca10(PO4) 6(OH)2}. Secreted apatite crystals are integral to the structural rigidity of the bone. When a bone breaks, there is often a need to implant an orthotic device to support the broken bone during remodeling. Current technologies use either metal pins and screws that need to be removed (by surgery) once the healing is complete or polymeric materials that either get resorbed or are porous enough to allow bone ingrowth. Poly(L)Lactic acid and copolymers of polyglycolic acid (PGA) are thermoplastics which show promise as the matrix material in biosorbable/load bearing implants. In service this material is hydrolyzed generating water and L-lactate. Orthoses composed of neat PLLA resins require greater than three years for complete resorbtion, however; 95% of strength is lost in 2 to 3 weeks in-vitro. This has limited the deployment of load bearing PLLA to screws, pins or short bracing spans. There exists a need for the development of an implantable and biosorbable orthotic device which will retain its structural integrity long enough for remodeling and healing process to generate new bone material, about 10 weeks. The scope of this dissertation is the development of HAP nano-whisker reinforcement and a HAP/PLLA thermoplastic composite. As proof of the feasibility of generating nano-reinforcement PLLA-composites, the surface of a galleried clay, montmorillonite, was modified and clay/PLLA composites processed and then characterized. Hydroxyapatite nano-whiskers were synthesized and functionalized using organosilanes and Menhaden fish-oil (common organic dispersant). The functionalized nano-fibers were used to process HAP/PLLA composites. Characterization techniques included thermal analysis, magnetic spectroscopy, XRD and ICP analysis and electron microscopy. The

  15. Nitrate removal properties of solid-phase denitrification processes using acid-blended poly(L-lactic acid) as the sole substrate

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Matsuoka, H.; Sun, J.; Yoshikawa, S.; Tsuji, H.; Hiraishi, A.

    2013-04-01

    The large amount of waste that is discharged along with the diffusion of poly(L-lactic acid) (PLLA) articles in use is persistent concern. Previously, we studied solid-phase denitrification (SPD) processes using PLLA to establish an effective re-use of PLLA waste. We found that PLLA with a weight-average molecular weight (Mw) of approximately 10,000 was suitable for SPD processes; however, the recycling of PLLA waste consumes a high energy. A new PLLA plastic including 5% poly(ethylene oxalate) (PEOxPLLA) as a blend material has attracted attention because recycling of PEOxPLLA consumes less electricity than that of PLLA. In this study, our main objectives were to evaluate whether PEOxPLLA can be used for SPD processes by changing its Mw and to investigate the bioavailability for denitrification of hydrolysates released from PEOxPLLA. The predicted hydrolysates, including oxalic acid, ethylene glycol, and lactate, are abiotically released, leading to different biological nitrate removal rates. Consequently, the nitrate removal rate of PEOxPLLA ranged from 0.9-4.1 mg-NO3--N·g-MLSS·h-1 by changing the Mw in the range of 8,500-238,000. In culture-dependent approaches, denitrifying bacteria using each substrate as an electron donor are found in activated sludge, suggesting that all hydrolysates functioned in the SPD processes using PEOxPLLA.

  16. Novel biodegradable poly(propylene fumarate)-co-poly(l-lactic acid) porous scaffolds fabricated by phase separation for tissue engineering applications

    PubMed Central

    Liu, Xifeng; Miller, A. Lee; Waletzki, Brian E.; Yaszemski, Michael J.

    2015-01-01

    Scaffolds with intrinsically interconnected porous structures are highly desirable in tissue engineering and regenerative medicine. In this study, three-dimensional polymer scaffolds with highly interconnected porous structures were fabricated by thermally induced phase separation of novel synthesized biodegradable poly(propylene fumarate)-co-poly(l-lactic acid) in a dioxane/water binary system. Defined porous scaffolds were achieved by optimizing conditions to attain interconnected porous structures. The effect of phase separation parameters on scaffold morphology were investigated, including polymer concentration (1, 3, 5, 7, and 9%), quench time (1, 4, and 8 min), dioxane/water ratio (83/17, 85/15, and 87/13 wt/wt), and freeze temperature (−20, −80, and −196 °C). Interesting pore morphologies were created by adjusting these processing parameters, e.g., flower-shaped (5%; 85/15; 1 min; −80 °C), spherulite-like (5%; 85/15; 8 min; −80 °C), and bead-like (5%; 87/13; 1 min; −80 °C) morphology. Modulation of phase separation conditions also resulted in remarkable differences in scaffold porosities (81% to 91%) and thermal properties. Furthermore, scaffolds with varied mechanic strengths, degradation rates, and protein adsorption capabilities could be fabricated using the phase separation method. In summary, this work provides an effective route to generate multi-dimensional porous scaffolds that can be applied to a variety of hydrophobic polymers and copolymers. The generated scaffolds could potentially be useful for various tissue engineering applications including bone tissue engineering. PMID:26989483

  17. Electrophoretic Deposition of Dexamethasone-Loaded Mesoporous Silica Nanoparticles onto Poly(L-Lactic Acid)/Poly(ε-Caprolactone) Composite Scaffold for Bone Tissue Engineering.

    PubMed

    Qiu, Kexin; Chen, Bo; Nie, Wei; Zhou, Xiaojun; Feng, Wei; Wang, Weizhong; Chen, Liang; Mo, Xiumei; Wei, Youzhen; He, Chuanglong

    2016-02-17

    The incorporation of microcarriers as drug delivery vehicles into polymeric scaffold for bone regeneration has aroused increasing interest. In this study, the aminated mesoporous silica nanoparticles (MSNs-NH2) were prepared and used as microcarriers for dexamethasone (DEX) loading. Poly(l-lactic acid)/poly(ε-caprolactone) (PLLA/PCL) nanofibrous scaffold was fabricated via thermally induced phase separation (TIPS) and served as template, onto which the drug-loaded MSNs-NH2 nanoparticles were deposited by electrophoretic deposition (EPD). The physicochemical and release properties of the prepared scaffolds (DEX@MSNs-NH2/PLLA/PCL) were examined, and their osteogenic activities were also evaluated through in vitro and in vivo studies. The release of DEX from the scaffolds revealed an initial rapid release followed by a slower and sustained one. The in vitro results indicated that the DEX@MSNs-NH2/PLLA/PCL scaffold exhibited good biocompatibility to rat bone marrow-derived mesenchymal stem cells (BMSCs). Also, BMSCs cultured on the DEX@MSNs-NH2/PLLA/PCL scaffold exhibited a higher degree of osteogenic differentiation than those cultured on PLLA/PCL and MSNs-NH2/PLLA/PCL scaffolds, in terms of alkaline phosphatase (ALP) activity, mineralized matrix formation, and osteocalcin (OCN) expression. Furthermore, the in vivo results in a calvarial defect model of Sprague-Dawley (SD) rats demonstrated that the DEX@MSNs-NH2/PLLA/PCL scaffold could significantly promote calvarial defect healing compared with the PLLA/PCL scaffold. Thus, the EPD technique provides a convenient way to incorporate osteogenic agents-containing microcarriers to polymer scaffold, and thus, prepared composite scaffold could be a potential candidate for bone tissue engineering application due to its capacity for delivery of osteogenic agents. PMID:26736029

  18. The history behind the use of injectable poly-L-lactic acid for facial and nonfacial volumization: the positive impact of evolving methodology.

    PubMed

    Vleggaar, Danny; Fitzgerald, Rebecca; Lorenc, Z Paul

    2014-04-01

    Poly-L-lactic acid (PLLA) was first approved for soft tissue augmentation in Europe in 1999 for the cosmetic correction of scars and wrinkles. Due, in part, to inadequate usage recommendations that included those related to product reconstitution and hydration, injection sites, techniques, and timing, and patient selection, PLLA use was initially associated with suboptimal cosmetic benefit and a high rate of specific adverse events, such as the formation of nodules. As clinical experience with PLLA has increased, the implementation of specific methodological changes has allowed greater, more consistent cosmetic effects to be achieved, with a low rate of adverse events. This enhanced PLLA methodology, coupled with an evolving understanding of the interplay between structures in the aging face, now allows predictably favorable results across a broad range of patient types. PMID:24719075

  19. Validation of an Ultraviolet-visible (UV-Vis) technique for the quantitative determination of curcumin in poly(L-lactic acid) nanoparticles.

    PubMed

    Silva-Buzanello, Rosana Aparecida da; Ferro, Ana Caroline; Bona, Evandro; Cardozo-Filho, Lúcio; Araújo, Pedro Henrique Hermes de; Leimann, Fernanda Vitória; Gonçalves, Odinei Hess

    2015-04-01

    Curcumin is a natural yellow-orange pigment extracted from turmeric and is a potential substitute of health-dangerous artificial dyes. Nanoencapsulation in biodegradable polymers is a promising alternative to improve curcumin stability and water solubility but curcumin concentration inside the nanoparticles must be precisely known. A reliable method to determine the actual curcumin concentration must be validated since the validation procedures warrant that the method is adequate and sufficient for the specific application involved. This work describes the validation parameters given by the International Conference on Harmonisation (ICH) guidelines to adopt an analytical method based on Ultraviolet-visible spectroscopy for the quantitative determination of curcumin encapsulated in poly(l-lactic acid) nanoparticles. This method was validated in respect to linearity, detection limit, quantification limit, accuracy and precision. Studies on the analytical procedure validation warranted safety in final results obtained for the curcumin concentration in the nanoparticles. PMID:25442529

  20. Induction of chondrogenic differentiation in mesenchymal stem cells by TGF-beta cross-linked to collagen-PLLA [poly(L-lactic acid)] scaffold by transglutaminase 2

    PubMed Central

    Niger, Corinne; Beazley, Kelly E.; Nurminskaya, Maria

    2013-01-01

    Transglutaminase-mediated cross-linking has been employed to optimize the mechanical properties and stability of tissue scaffolds. We have characterized tissue transglutaminase (TG2)-mediated cross-linking as a useful tool to deliver biologically-active TGF to mesenchymal stem cells (MSCs) and direct their differentiation towards a chondrogenic lineage. TGF- 3 is irreversibly cross-linked by TG2 to collagen type II-coated PLLA [poly(L-lactic acid)] nanofibrous scaffolds and activates Smad phosphorylation and Smad-dependent expression of a luciferase reporter. Human bone marrow-derived MSCs cultured on these scaffolds deposit cartilaginous matrix after 14 days of culture at 50% efficiency compared to chondrogenesis in the presence of soluble TGF- 3. These findings are significant because they suggest a novel approach for the programming of MSCs in a spatially controlled manner by immobilizing biologically active TGF- 3 via cross-linking to a collagen-coated polymeric scaffold. PMID:23892982

  1. Antibody immobilization on poly(L-lactic acid) nanofibers advantageously carried out by means of a non-equilibrium atmospheric plasma process

    NASA Astrophysics Data System (ADS)

    Dolci, L. S.; Liguori, A.; Merlettini, A.; Calzà, L.; Castellucci, M.; Gherardi, M.; Colombo, V.; Focarete, M. L.

    2016-07-01

    In the present study, the comparison between a conventional wet-chemical method and a non-equilibrium atmospheric pressure plasma process for the conjugation of biomolecules on the surface of poly(L-lactic acid) (PLLA) electrospun fibers is reported. Physico-chemical and morphological characteristics of chemically and plasma functionalized mats are studied and compared with those of pristine mats. The efficiency in biomolecules immobilization is assessed by the covalent conjugation of an antibody (anti-CD10) on the functionalized PLLA fibers. The achieved results highlight that the proposed plasma process enables antibodies to be successfully immobilized on the surface of PLLA fibers, demonstrating that non-equilibrium atmospheric pressure plasma can be an effective, highly flexible and environmentally friendly alternative to the still widely employed wet-chemical methods for the conjugation of biomolecules onto biomaterials.

  2. Poly-(L-lactic acid) and citric acid-crosslinked gelatin composite matrices as a drug-eluting stent coating material with endothelialization, antithrombogenic, and drug release properties.

    PubMed

    Inoue, Motoki; Sasaki, Makoto; Katada, Yasuyuki; Fujiu, Katsuhito; Manabe, Ichiro; Nagai, Ryozo; Taguchi, Tetsushi

    2013-07-01

    Biodegradable composite matrices comprising poly-(L-lactic acid) (PLLA) and citric acid-crosslinked alkali-treated gelatin (AlGelatin) with endothelialization, antithrombogenic, and drug release properties were prepared. The characterization of composite matrices with various mixing ratios was performed by evaluating their swelling ratio, endothelial cell culture, antithrombogenic tests, and drug release behavior. Tamibarotene (Am80), which specifically inhibits smooth muscle cell proliferation, was employed as the drug. The swelling ratio of composite matrices decreased as the PLLA content decreased. The number of endothelial cells cultured on the surfaces of composite matrices was maximal at the PLLA/AlGelatin-TSC ratio of 80/20. Antithrombogenic tests revealed that the levels of platelets and fibrin network formation decreased as the AlGelatin-TSC content increased. The Am80 release test indicated that the release rate decreased as PLLA content increased. Using the resulting composite matrix, Am80-eluting stents possessing a smooth surface and a coating thickness of ∼15 μm were successfully obtained. Am80 was continuously released from the resulting stent at ∼40%, up to 28 days without burst release. Therefore, Am80-eluting stent with its antithrombogenic and endothelialization properties has great potential for clinical use. PMID:23280946

  3. Surface Mechanical and Rheological Behaviors of Biocompatible Poly((D,L-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA-PEG) and Poly((D,L-lactic acid-ran-glycolic acid-ran-ε-caprolactone)-block-ethylene glycol) (PLGACL-PEG) Block Copolymers at the Air-Water Interface.

    PubMed

    Kim, Hyun Chang; Lee, Hoyoung; Khetan, Jawahar; Won, You-Yeon

    2015-12-29

    Air-water interfacial monolayers of poly((D,L-lactic acid-ran-glycolic acid)-block-ethylene glycol) (PLGA-PEG) exhibit an exponential increase in surface pressure under high monolayer compression. In order to understand the molecular origin of this behavior, a combined experimental and theoretical investigation (including surface pressure-area isotherm, X-ray reflectivity (XR) and interfacial rheological measurements, and a self-consistent field (SCF) theoretical analysis) was performed on air-water monolayers formed by a PLGA-PEG diblock copolymer and also by a nonglassy analogue of this diblock copolymer, poly((D,L-lactic acid-ran-glycolic acid-ran-caprolactone)-block-ethylene glycol) (PLGACL-PEG). The combined results of this study show that the two mechanisms, i.e., the glass transition of the collapsed PLGA film and the lateral repulsion of the PEG brush chains that occur simultaneously under lateral compression of the monolayer, are both responsible for the observed PLGA-PEG isotherm behavior. Upon cessation of compression, the high surface pressure of the PLGA-PEG monolayer typically relaxes over time with a stretched exponential decay, suggesting that in this diblock copolymer situation, the hydrophobic domain formed by the PLGA blocks undergoes glass transition in the high lateral compression state, analogously to the PLGA homopolymer monolayer. In the high PEG grafting density regime, the contribution of the PEG brush chains to the high monolayer surface pressure is significantly lower than what is predicted by the SCF model because of the many-body attraction among PEG segments (referred to in the literature as the "n-cluster" effects). The end-grafted PEG chains were found to be protein resistant even under the influence of the "n-cluster" effects. PMID:26633595

  4. Degradation of Poly(L-Lactic Acid) and Bio-Composites by Alkaline Medium under Various Temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ribbons of poly(lactic acid) (PLA) and PLA containing 10 or 25 % Osage orange (OO) biocomposites of various sized heartwood particles were exposed to non-composting soil conditions either outdoors or in a greenhouse. No appreciable degradation was evident even after 208 day treatments. An artifici...

  5. Three-layer microfibrous peripheral nerve guide conduit composed of elastin-laminin mimetic artificial protein and poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Kakinoki, Sachiro; Nakayama, Midori; Moritan, Toshiyuki; Yamaoka, Tetsuji

    2014-07-01

    We developed a microfibrous poly(L-lactic acid) (PLLA) nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG)30) that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical stremgth to the conduit. A 10% poly(ethylene glycol) was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG)30 composisting of an elastin-like repetitive sequence (VPGIG)30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73) was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG)30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG)30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG)30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG)30 inner layer.

  6. Fabrication of Microfibrous and Nano-/Microfibrous Scaffolds: Melt and Hybrid Electrospinning and Surface Modification of Poly(L-lactic acid) with Plasticizer

    PubMed Central

    Yoon, Young Il; Park, Ko Eun; Lee, Seung Jin; Park, Won Ho

    2013-01-01

    Biodegradable poly(L-lactic acid) (PLA) fibrous scaffolds were prepared by electrospinning from a PLA melt containing poly(ethylene glycol) (PEG) as a plasticizer to obtain thinner fibers. The effects of PEG on the melt electrospinning of PLA were examined in terms of the melt viscosity and fiber diameter. Among the parameters, the content of PEG had a more significant effect on the average fiber diameter and its distribution than those of the spinning temperature. Furthermore, nano-/microfibrous silk fibroin (SF)/PLA and PLA/PLA composite scaffolds were fabricated by hybrid electrospinning, which involved a combination of solution electrospinning and melt electrospinning. The SF/PLA (20/80) scaffolds consisted of a randomly oriented structure of PLA microfibers (average fiber diameter = 8.9 µm) and SF nanofibers (average fiber diameter = 820 nm). The PLA nano-/microfiber (20/80) scaffolds were found to have similar pore parameters to the PLA microfiber scaffolds. The PLA scaffolds were treated with plasma in the presence of either oxygen or ammonia gas to modify the surface of the fibers. This approach of controlling the surface properties and diameter of fibers could be useful in the design and tailoring of novel scaffolds for tissue engineering. PMID:24381937

  7. Three-layer microfibrous peripheral nerve guide conduit composed of elastin-laminin mimetic artificial protein and poly(L-lactic acid)

    PubMed Central

    Kakinoki, Sachiro; Nakayama, Midori; Moritan, Toshiyuki; Yamaoka, Tetsuji

    2014-01-01

    We developed a microfibrous poly(L-lactic acid) (PLLA) nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG)30) that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical strength to the conduit. A 10% poly(ethylene glycol) was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG)30 compositing of an elastin-like repetitive sequence (VPGIG)30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73) was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG)30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG)30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG)30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG)30 inner layer. PMID:25101261

  8. Cellular behaviour of hepatocyte-like cells from nude mouse bone marrow-derived mesenchymal stem cells on galactosylated poly(D,L-lactic-co-glycolic acid).

    PubMed

    Roh, Hyun; Yang, Dae Hyeok; Chun, Heung Jae; Khang, Gilson

    2015-07-01

    Previously, the galactosylation of poly(d,l-lactic-co-glycolic acid) (PLGA) surface was accomplished by grafting allylamine (AA), using inductively coupled plasma-assisted chemical vapour deposition (ICP-CVD) and conjugating lactobionic acid (LA) with AA via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide (EDC/NHS) activation for hepatic tissue-engineering purposes. As a continuation study, the cellular behaviour of hepatocyte-like cells (HLCs) on the surface of the galactosylated PLGA were investigated. Nude mouse bone marrow-derived mesenchymal stem cells (MSCs) were cultured under hepatogenic conditions and the differentiated cells were characterized by reverse-transcription polymerase chain reaction (RT-PCR), immunofluorescence and periodic acid-Schiff (PAS) staining. Galactosylated PLGA enhanced the proliferation rate of HLCs compared to the control; HLCs on the surface of the sample became aggregated and formed spheroids after 3 days of culture. A large number of cells on the surface of the sample exhibited increased liver-specific functional activities, such as albumin and urea secretions. In addition, multicellular spheroids in the sample strongly expressed phospholyated focal adhesion kinase (pFAK) (cell-matrix interactions), E-cadherin (cell-cell interactions) and connexin 32 (Cox32; gap junction). PMID:23784953

  9. Understanding, avoiding, and treating potential adverse events following the use of injectable poly-L-lactic acid for facial and nonfacial volumization.

    PubMed

    Vleggaar, Danny; Fitzgerald, Rebecca; Lorenc, Z Paul

    2014-04-01

    Injection-related adverse events (AEs) may occur with the use of any injectable substance, including all commercially available fillers. The most common of these AEs include discomfort, bruising, edema, and erythema, which are generally transient and resolve spontaneously. The majority of AEs widely felt to be associated with poly-L-lactic acid (PLLA) are papules, nodules, and granulomas. Papules and nodules, which are histologically distinct from granulomas, tend to arise several weeks after injection, are generally palpable, asymptomatic, and nonvisible, and will typically resolve on their own, but can be camouflaged with the use of hyaluronic acid. They generally result from suboptimal product reconstitution or placement and, as such, their incidence can be minimized by improved injection methodology. In contrast, true inflammatory granulomas are very rare (incidence 0.01%-0.1%), seem to be systemic in nature, and represent an overabundance of host reaction to PLLA. Granulomas may become apparent months or years post-injection and may persist and grow over time. Their treatment is geared toward halting the increased secretion of interstitial substances and invasion of cells, and may include the administration of steroids and antimetabolites such as 5-fluorouracil. PMID:24719076

  10. In Vitro Corrosion and Cytocompatibility of a Microarc Oxidation Coating and Poly(l-lactic acid) Composite Coating on Mg-1Li-1Ca Alloy for Orthopedic Implants.

    PubMed

    Zeng, Rong-Chang; Cui, Lan-Yue; Jiang, Ke; Liu, Rui; Zhao, Bao-Dong; Zheng, Yu-Feng

    2016-04-20

    Manipulating the degradation rate of biomedical magnesium alloys poses a challenge. The characteristics of a microarc oxidation (MAO), prepared in phytic acid, and poly(l-lactic acid) (PLLA) composite coating, fabricated on a novel Mg-1Li-1Ca alloy, were studied through field emission scanning electron microscopy (FE-SEM), electron probe X-ray microanalysis (EPMA), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The corrosion behaviors of the samples were evaluated via hydrogen evolution, potentiodynamic polarization and electrochemical impedance spectroscopy in Hanks' solution. The results indicated that the MAO/PLLA composite coatings significantly enhanced the corrosion resistance of the Mg-1Li-1Ca alloy. MTT and ALP assays using MC3T3 osteoblasts indicated that the MAO/PLLA coatings greatly improved the cytocompatibility, and the morphology of the cells cultured on different samples exhibited good adhesion. Hemolysis tests showed that the composite coatings endowed the Mg-1Li-1Ca alloys with a low hemolysis ratio. The increased solution pH resulting from the corrosion of magnesium could be tailored by the degradation of PLLA. The degradation mechanism of the composite coatings was discussed. The MAO/PLLA composite coating may be appropriate for applications on degradable Mg-based orthopedic implants. PMID:27022831

  11. L-Lactic Acid Production by Lactobacillus rhamnosus ATCC 10863

    PubMed Central

    Senedese, Ana Lívia Chemeli; Maciel Filho, Rubens; Maciel, Maria Regina Wolf

    2015-01-01

    Lactic acid has been shown to have the most promising application in biomaterials as poly(lactic acid). L. rhamnosus ATCC 10863 that produces L-lactic acid was used to perform the fermentation and molasses was used as substrate. A solution containing 27.6 g/L of sucrose (main composition of molasses) and 3.0 g/L of yeast extract was prepared, considering the final volume of 3,571 mL (14.0% (v/v) inoculum). Batch and fed batch fermentations were performed with temperature of 43.4°C and pH of 5.0. At the fed batch, three molasses feed were applied at 12, 24, and 36 hours. Samples were taken every two hours and the amounts of lactic acid, sucrose, glucose, and fructose were determined by HPLC. The sucrose was barely consumed at both processes; otherwise the glucose and fructose were almost entirely consumed. 16.5 g/L of lactic acid was produced at batch and 22.0 g/L at fed batch. Considering that lactic acid was produced due to the low concentration of the well consumed sugars, the final amount was considerable. The cell growth was checked and no substrate inhibition was observed. A sucrose molasses hydrolysis is suggested to better avail the molasses fermentation with this strain, surely increasing the L-lactic acid. PMID:25922852

  12. Lysine-doped polypyrrole/spider silk protein/poly(l-lactic) acid containing nerve growth factor composite fibers for neural application.

    PubMed

    Zhang, Hong; Wang, Kefeng; Xing, Yiming; Yu, Qiaozhen

    2015-11-01

    Lysine-doped polypyrrole (PPy)/regenerated spider silk protein (RSSP)/poly(l-lactic) acid (PLLA)/nerve growth factor (NGF) (L-PRPN) composite scaffold was fabricated by co-axial electrospraying and electrospinning. This L-PRPN composite scaffold had a structure of microfibers with a core-shell structure as the stems and nanofibers as branches. Assessment in vitro demonstrated that the L-PRPN composite micro/nano-fibrous scaffold could maintain integrated structure for at least 4months and the pH value of PBS at about 7.28. It had good biocompatibility and cell adhesion and relatively stable conductivity. PC 12 cells cultured on this scaffold, anisotropic cell-neurite-cell-neurite or neurite-neurite sheets were formed after being cultured for 6days. Evaluations in vivo also showed that L-PRPN composite fibrous conduit was effective at bridging 2.0cm sciatic nerve gap in adult rat within 10months. This conduit and electrical stimulation (ES) through it promoted Schwann cell migration and axonal regrowth. PMID:26249628

  13. Antibacterial activity and biological performance of a novel antibacterial coating containing a halogenated furanone compound loaded poly(L-lactic acid) nanoparticles on microarc-oxidized titanium.

    PubMed

    Cheng, Yicheng; Zhao, Xianghui; Liu, Xianghui; Sun, Weige; Ren, Huifang; Gao, Bo; Wu, Jiang

    2015-01-01

    Titanium implants have been widely used for many medical applications, but bacterial infection after implant surgery remains one of the most common and intractable complications. To this end, long-term antibacterial ability of the implant surface is highly desirable to prevent implant-associated infection. In this study, a novel antibacterial coating containing a new antibacterial agent, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone loaded poly(L-lactic acid) nanoparticles, was fabricated on microarc-oxidized titanium for this purpose. The antibacterial coating produced a unique inhibition zone against Staphylococcus aureus throughout a 60-day study period, which is normally long enough to prevent the infection around implants in the early and intermediate stages. The antibacterial rate for adherent S. aureus was about 100% in the first 10 days and constantly remained over 90% in the following 20 days. Fluorescence staining of adherent S. aureus also confirmed the excellent antibacterial ability of the antibacterial coating. Moreover, in vitro experiments showed an enhanced osteoblast adhesion and proliferation on the antibacterial coating, and more notable cell spread was observed at the early stage. It is therefore concluded that the fabricated antibacterial coating, which exhibits relatively long-term antibacterial ability and excellent biological performance, is a potential and promising strategy to prevent implant-associated infection. PMID:25632231

  14. Improving cytoactive of endothelial cell by introducing fibronectin to the surface of poly L-Lactic acid fiber mats via dopamine.

    PubMed

    Yang, Wufeng; Zhang, Xiazhi; Wu, Keke; Liu, Xiaoyan; Jiao, Yanpeng; Zhou, Changren

    2016-12-01

    A simple but straightforward approach was reported to prepare fiber mats modified with fibronectin (Fn) protein for endothelial cells activity study. Based on the self-polymerization and strong adhesion feature of dopamine, poly L-Lactic acid (PLLA) fibers mat was modified via simply immersing them into dopamine solution for 16h. Subsequently, Fn was immobilized onto the fiber mats surface by the coupling reactive polydopamine (PDA) layer and Fn. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to determine the chemical compositions of fiber mats surface, which confirmed the successful immobilization of PDA and Fn molecules on the fiber surface. Scanning electronic microscopy (SEM) was used to observe the surface morphology changes after modification with PDA and Fn. The data of water contact angle showed that the hydrophilicity of the fiber mats was improved after surface modification. The data of in vitro cell culture proved that the PDA and Fn modified surface significantly enhanced the adhesion, proliferation and cell activity of endothelial cells on the fiber mats. And the release of tumor necrosis factor-α (TNF-α) by endothelial cells on the modified surface was suppressed compared to that on culture plate and PLLA film at 2 and 4days, while the secretion of interleukin-1β (IL-1β) was increased compared to that on culture plate and PLLA film at 2days. PMID:27612725

  15. Fabrication of Poly-l-lactic Acid/Dicalcium Phosphate Dihydrate Composite Scaffolds with High Mechanical Strength—Implications for Bone Tissue Engineering

    PubMed Central

    Tanataweethum, Nida; Liu, Wai Ching; Scott Goebel, W.; Li, Ding; Chu, Tien Min

    2015-01-01

    Scaffolds were fabricated from poly-l-lactic acid (PLLA)/dicalcium phosphate dihydrate (DCPD) composite by indirect casting. Sodium citrate and PLLA were used to improve the mechanical properties of the DCPD scaffolds. The resulting PLLA/DCPD composite scaffold had increased diametral tensile strength and fracture energy when compared to DCPD only scaffolds (1.05 vs. 2.70 MPa and 2.53 vs. 12.67 N-mm, respectively). Sodium citrate alone accelerated the degradation rate by 1.5 times independent of PLLA. Cytocompatibility of all samples were evaluated using proliferation and differentiation parameters of dog-bone marrow stromal cells (dog-BMSCs). The results showed that viable dog-BMSCs attached well on both DCPD and PLLA/DCPD composite surfaces. In both DCPD and PLLA/DCPD conditioned medium, dog-BMSCs proliferated well and expressed alkaline phosphatase (ALP) activity indicating cell differentiation. These findings indicate that incorporating both sodium citrate and PLLA could effectively improve mechanical strength and biocompatibility without increasing the degradation time of calcium phosphate cement scaffolds for bone tissue engineering purposes. PMID:26556380

  16. Biocompatibility and biomechanical characteristics of loofah based scaffolds combined with hydroxyapatite, cellulose, poly-l-lactic acid with chondrocyte-like cells.

    PubMed

    Cecen, Berivan; Kozaci, Leyla Didem; Yuksel, Mithat; Ustun, Ozcan; Ergur, Bekir Ugur; Havitcioglu, Hasan

    2016-12-01

    The current study reports the biocompatibility and biomechanical characteristics of loofah-based scaffolds combined with hydroxyapatite (HA), cellulose, poly-l-lactic acid (PLLA) with chondrocytes-like cells. Scanning electron microscope (SEM) micrographs of the scaffolds showed that the addition of PLLA usually resulted in an increase in cell's attachment on scaffolds. Mechanical and elemental analyzes were assessed using tensile test and Energy Dispersive X-ray spectrometry (EDS), respectively. In summary, we showed that the loofah+PLLA+HA scaffolds perform significantly better than other loofah-based scaffolds employed in terms of increasing a diversity of mechanical properties including tensile strength and Young's modulus. Based on the analysis of the differential scanning calorimetry (DSC) thermograms and EDS spectrums that give an idea about the calcium phosphate (CaP) ratios, the improvement in the mechanical properties could principally be recognized to the strong interaction formed between loofah, PLLA and HA. The viability of chondrocytes on loofah-based scaffolds was analyzed by XTT tests. However, none of the scaffolds have proved to be toxic in metabolic activity. The histological evaluation obtained by hematoxylin and eosin (H&E), Masson trichrome, toluidine blue and immunohistochemistry methods showed that cells in all scaffolds produced extracellular matrix that defined proteoglycan and type I-II collagens. The results of this study suggest that the loofah-based scaffold with desirable properties can be considered as an ideal candidate for cartilage tissue engineering applications. PMID:27612733

  17. Subchronic toxicity and immunotoxicity of MeO-PEG-poly(D,L-lactic-co-glycolic acid)-PEG-OMe triblock copolymer nanoparticles delivered intravenously into rats

    NASA Astrophysics Data System (ADS)

    Liao, Longfei; Zhang, Mengtian; Liu, Huan; Zhang, Xuanmiao; Xie, Zhaolu; Zhang, Zhirong; Gong, Tao; Sun, Xun

    2014-06-01

    Although monomethoxy(polyethyleneglycol)-poly (D,L-lactic-co-glycolic acid)-monomethoxy (PELGE) nanoparticles have been widely studied as a drug delivery system, little is known about their toxicity in vivo. Here we examined the subchronic toxicity and immunotoxicity of different doses of PELGE nanoparticles with diameters of 50 and 200 nm (PELGE50 and PELGE200) in rats. Neither size of PELGE nanoparticles showed obvious subchronic toxic effects during 28 d of continuous intravenous administration based on clinical observation, body weight, hematology parameters and histopathology analysis. PELGE200 nanoparticles showed no overt signs of immunotoxicity based on organ coefficients, histopathology analysis, immunoglobulin levels, blood lymphocyte subpopulations and splenocyte cytokines. Conversely, PELGE50 nanoparticles were associated with an increased organ coefficient and histopathological changes in the spleen, increased serum IgM and IgG levels, alterations in blood lymphocyte subpopulations and enhanced expression of spleen interferon-γ. Taken together, these results suggest that PELGE nanoparticles show low subchronic toxicity but substantial immunotoxicity, which depends strongly on particle size. These findings will be useful for safe application of PELGE nanoparticles in drug delivery systems.

  18. The Maxillary Sinus Floor Elevation Using a Poly-L-Lactic Acid Device to Create Space Without Bone Graft: Case Series Study of Five Patients.

    PubMed

    Munakata, Motohiro; Tachikawa, Noriko; Yamaguchi, Yoko; Sanda, Minoru; Kasugai, Shohei

    2016-06-01

    Maxillary sinus floor elevation using autologous or alloplastic bone grafting is often performed for implant treatment of maxillary molars; however, issues related to the donor site and complications such as infection have been reported. We performed maxillary sinus floor elevation using poly-L-lactic acid (PLLA) as a space-making material in patients with an insufficient bone mass (<3 mm) for simultaneous implantation between the alveolar crest and floor of the maxillary sinus and evaluated the newly formed bone. Conventional antrostomy of the maxillary sinus from the lateral wall was performed, and PLLA was placed on the floor of the maxillary sinus after elevating the sinus membrane. Six months after surgery, the bone mass and density were measured using quantitative computed tomography, and histological evaluation was performed. No complications were recorded. Radiological findings showed a bone-like radiopaque appearance, and histological examination revealed new bone formation in all patients. In cases with insufficient bone mass prior to simultaneous implant placement, this method of maxillary sinus augmentation allows for sufficient bone augmentation without bone grafting. PMID:26829411

  19. Poly(l-Lactic Acid)/Gelatin Fibrous Scaffold Loaded with Simvastatin/Beta-Cyclodextrin-Modified Hydroxyapatite Inclusion Complex for Bone Tissue Regeneration.

    PubMed

    Lee, Jung Bok; Kim, Ji Eun; Balikov, Daniel A; Bae, Min Soo; Heo, Dong Nyoung; Lee, Donghyun; Rim, Hyun Joon; Lee, Deok-Won; Sung, Hak-Joon; Kwon, Il Keun

    2016-07-01

    Recently, the application of nanostructured materials in the field of tissue engineering has garnered attention to mediate treatment and regeneration of bone defects. In this study, poly(l-lactic acid) (PLLA)/gelatin (PG) fibrous scaffolds are fabricated and β-cyclodextrin (βCD) grafted nano-hydroxyapatite (HAp) is coated onto the fibrous scaffold surface via an interaction between βCD and adamantane. Simvastatin (SIM), which is known to promote osteoblast viability and differentiation, is loaded into the remaining βCD. The specimen morphologies are characterized by scanning electron microscopy. The release profile of SIM from the drug loaded scaffold is also evaluated. In vitro proliferation and osteogenic differentiation of human adipose derived stem cells on SIM/HAp coated PG composite scaffolds is characterized by alkaline phosphatase (ALP) activity, mineralization (Alizarin Red S staining), and real time Polymerase chain reaction (PCR). The scaffolds are then implanted into rabbit calvarial defects and analyzed by microcomputed tomography for bone formation after four and eight weeks. These results demonstrate that SIM loaded PLLA/gelatin/HAp-(βCD) scaffolds promote significantly higher ALP activity, mineralization, osteogenic gene expression, and bone regeneration than control scaffolds. This suggests the potential application of this material toward bone tissue engineering. PMID:26996294

  20. In vivo evaluation of an antibacterial coating containing halogenated furanone compound-loaded poly(l-lactic acid) nanoparticles on microarc-oxidized titanium implants.

    PubMed

    Cheng, Yicheng; Gao, Bo; Liu, Xianghui; Zhao, Xianghui; Sun, Weige; Ren, Huifang; Wu, Jiang

    2016-01-01

    To prevent peri-implant infection, a new antibacterial coating containing a halogenated furanone compound, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone-loaded poly(l-lactic acid) nanoparticles, has been fabricated. The current study was designed to evaluate the preventive effect of the antibacterial coating under a simulated environment of peri-implant infection in vivo. Microarc-oxidized titanium implants treated with minocycline hydrochloride ointment were used as positive control group, and microarc-oxidized titanium implants without any treatment were used as blank control group. Three kinds of implants were implanted in dogs' mandibles, and the peri-implant infection was simulated by silk ligation and feeding high sugar diet. After 2-month implantation, the results showed that no significant differences were detected between the experimental and positive control groups (P>0.05), but the data of clinical measurements of the blank control group were significantly higher than those of the other two groups (P<0.05), and the bone-implant contact rate and ultimate interfacial strength were significantly lower than those of the other two groups (P<0.05). Scanning electron microscope observation and histological examination showed that more new bone was formed on the surface of the experimental and positive control groups. It can be concluded that the antibacterial coating fabricated on implants has remarkable preventive effect on peri-implant infection at the early stage. PMID:27099494

  1. In vivo evaluation of an antibacterial coating containing halogenated furanone compound-loaded poly(l-lactic acid) nanoparticles on microarc-oxidized titanium implants

    PubMed Central

    Cheng, Yicheng; Gao, Bo; Liu, Xianghui; Zhao, Xianghui; Sun, Weige; Ren, Huifang; Wu, Jiang

    2016-01-01

    To prevent peri-implant infection, a new antibacterial coating containing a halogenated furanone compound, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone-loaded poly(l-lactic acid) nanoparticles, has been fabricated. The current study was designed to evaluate the preventive effect of the antibacterial coating under a simulated environment of peri-implant infection in vivo. Microarc-oxidized titanium implants treated with minocycline hydrochloride ointment were used as positive control group, and microarc-oxidized titanium implants without any treatment were used as blank control group. Three kinds of implants were implanted in dogs’ mandibles, and the peri-implant infection was simulated by silk ligation and feeding high sugar diet. After 2-month implantation, the results showed that no significant differences were detected between the experimental and positive control groups (P>0.05), but the data of clinical measurements of the blank control group were significantly higher than those of the other two groups (P<0.05), and the bone–implant contact rate and ultimate interfacial strength were significantly lower than those of the other two groups (P<0.05). Scanning electron microscope observation and histological examination showed that more new bone was formed on the surface of the experimental and positive control groups. It can be concluded that the antibacterial coating fabricated on implants has remarkable preventive effect on peri-implant infection at the early stage. PMID:27099494

  2. Antibacterial activity and biological performance of a novel antibacterial coating containing a halogenated furanone compound loaded poly(L-lactic acid) nanoparticles on microarc-oxidized titanium

    PubMed Central

    Cheng, Yicheng; Zhao, Xianghui; Liu, Xianghui; Sun, Weige; Ren, Huifang; Gao, Bo; Wu, Jiang

    2015-01-01

    Titanium implants have been widely used for many medical applications, but bacterial infection after implant surgery remains one of the most common and intractable complications. To this end, long-term antibacterial ability of the implant surface is highly desirable to prevent implant-associated infection. In this study, a novel antibacterial coating containing a new antibacterial agent, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone loaded poly(L-lactic acid) nanoparticles, was fabricated on microarc-oxidized titanium for this purpose. The antibacterial coating produced a unique inhibition zone against Staphylococcus aureus throughout a 60-day study period, which is normally long enough to prevent the infection around implants in the early and intermediate stages. The antibacterial rate for adherent S. aureus was about 100% in the first 10 days and constantly remained over 90% in the following 20 days. Fluorescence staining of adherent S. aureus also confirmed the excellent antibacterial ability of the antibacterial coating. Moreover, in vitro experiments showed an enhanced osteoblast adhesion and proliferation on the antibacterial coating, and more notable cell spread was observed at the early stage. It is therefore concluded that the fabricated antibacterial coating, which exhibits relatively long-term antibacterial ability and excellent biological performance, is a potential and promising strategy to prevent implant-associated infection. PMID:25632231

  3. Non-crystalline composite tissue engineering scaffolds using boron-containing bioactive glass and poly(D,L-lactic acid) coatings.

    PubMed

    Mantsos, T; Chatzistavrou, X; Roether, J A; Hupa, L; Arstila, H; Boccaccini, A R

    2009-10-01

    The aim of this study was the fabrication of three-dimensional, highly porous, bioactive scaffolds using a recently developed bioactive glass powder, denominated '0106', with nominal composition (in wt%): 50 SiO(2), 22.6 CaO, 5.9 Na(2)O, 4 P(2)O(5), 12 K(2)O, 5.3 MgO and 0.2 B(2)O(3). The optimum sintering conditions for the fabrication of scaffolds by the foam-replica method were identified (sintering temperature: 670 degrees C and dwell time: 5 h). Composite samples were also fabricated by applying a biopolymer coating of poly((D,L)-lactic acid) (PDLLA) using a dip coating process. The average compressive strength values were 0.4 MPa for uncoated and 0.6 MPa for coated scaffolds. In vitro bioactivity studies in simulated body fluid (SBF) showed that a carbonate hydroxyapatite (HCAp) layer was deposited on uncoated and coated scaffolds after only 4 days of immersion in SBF, demonstrating the high in vitro bioactivity of the scaffolds. It was also confirmed that the scaffold structure remained amorphous (no crystallization) after the specific heat treatment used, with scaffolds exhibiting mechanical properties and bioactivity suitable for use in bone tissue engineering applications. PMID:19776493

  4. The influence of γ-ray irradiation on the thermal stability and molecular weight of Poly(L-Lactic acid) and its nanocomposites

    NASA Astrophysics Data System (ADS)

    Yıldırım, Yeliz; Oral, Ayhan

    2014-03-01

    The gamma (γ) radiation effects on the thermal properties of Poly(L-Lactic acid) (PLLA), and three PLLA nanocomposites containing 1, 3 and 5% montmorillonite MK10 clay were investigated in different solvents such as tetrahydrofuran, chloroform and 1,4 dioxane. The polymers were irradiated by gamma radiation at low absorbed doses of 1, 5, and 10 kGy. The thermal properties and molecular weight of the unirradiated and irradiated PLLA and its nanocomposites were characterized by Thermogravimetry (TG) and Gel Permeation Chromatography (GPC), respectively. The TG curves showed that the thermal degradation of the unirradiated PLLA and its nanocomposites occurred in only one stage. The activation energies of thermal degradation (E) for irradiated and unirradiated PLLA and its nanocomposites were determined by the Flynn-Wall-Ozawa (FWO) method. The E values of the polymer irradiated with gamma radiation seem to be smaller than those of unirradiated sample due to polymer bond scission. In addition, the calculated G values of the polymer and nanocomposites showed that the polymer structure was less stable when exposed to radiation with increasing % MK10 content.

  5. Humidity-dependent compression-induced glass transition of the air-water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA).

    PubMed

    Kim, Hyun Chang; Lee, Hoyoung; Jung, Hyunjung; Choi, Yun Hwa; Meron, Mati; Lin, Binhua; Bang, Joona; Won, You-Yeon

    2015-07-28

    Constant rate compression isotherms of the air-water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA) show a distinct feature of an exponential increase in surface pressure in the high surface polymer concentration regime. We have previously demonstrated that this abrupt increase in surface pressure is linked to the glass transition of the polymer film, but the detailed mechanism of this process is not fully understood. In order to obtain a molecular-level understanding of this behavior, we performed extensive characterizations of the surface mechanical, structural and rheological properties of Langmuir PLGA films at the air-water interface, using combined experimental techniques including the Langmuir film balance, X-ray reflectivity and double-wall-ring interfacial rheometry methods. We observed that the mechanical and structural responses of the Langmuir PLGA films are significantly dependent on the rate of film compression; the glass transition was induced in the PLGA film only at fast compression rates. Surprisingly, we found that this deformation rate dependence is also dependent on the humidity of the environment. With water acting as a plasticizer for the PLGA material, the diffusion of water molecules through the PLGA film seems to be the key factor in the determination of the glass transformation properties and thus the mechanical response of the PLGA film against lateral compression. Based on our combined results, we hypothesize the following mechanism for the compression-induced glass transformation of the Langmuir PLGA film; (1) initially, a humidified/non-glassy PLGA film is formed in the full surface-coverage region (where the surface pressure shows a plateau) during compression; (2) further compression leads to the collapse of the PLGA chains and the formation of new surfaces on the air side of the film, and this newly formed top layer of the PLGA film is transiently glassy in character because the water evaporation rate

  6. Injectable poly-L: -lactic acid: a novel sculpting agent for the treatment of dermal fat atrophy after severe acne.

    PubMed

    Sadove, Richard

    2009-01-01

    Acne vulgaris affects up to 80% of people 11 to 30 years of age, and scarring can occur for up to 95% of these patients. Scarring may be pitted or hypertrophic in nature, although in most cases it is atrophic. Atrophic acne scarring follows dermal collagen and fat loss after moderate to severe acne infection. Injectable poly-L-acid (PLLA) is a biocompatible, biodegradable, synthetic polymer device that is hypothesized to enhance dermal volume via the endogenous production of fibroblasts and, subsequently, collagen. The gradual improvements in cutaneous volume observed after treatment with injectable PLLA have been noted to last up to 2 years. The case studies presented describe the use of injectable PLLA to correct dermal fat loss in macular atrophic acne scarring of the cheeks. Two female patients underwent three treatment sessions with injectable PLLA over a 12-week period. At each treatment session, the reconstituted product was injected into the deep dermis under the depressed portion of the scar. Both patients were extremely pleased with their results at, respectively, 1- and 4-year follow-up evaluations. Patients experienced minimal swelling and redness after injection and no product-related adverse events such as papule and/or nodule formation. The author believes these data suggest that injectable PLLA is a good treatment option for the correction of macular atropic scarring with thin dermis (off-label use), particularly compared with other injectable fillers currently used for this indication that have shorter durations of effect. PMID:18923863

  7. Influence of purified multiwalled carbon nanotubes on the mechanical and morphological behavior in poly (L-lactic acid) matrix.

    PubMed

    Leal, C V; Martinez, D S T; Más, B A; Alves, O L; Duek, E A R

    2016-06-01

    Poly (L-latic acid) (PLLA) is a bioresorbable polymer widely used as a biomaterial, but its fragility can limit its use. An alternative is to produce polymer nanocomposites, which can enhance the mechanical properties of polymeric matrix, resulting in a material with differentiated properties. In this work, PLLA based nanocomposites containing 0.25, 0.5 and 1.0wt% of purified multiwalled carbon nanotubes (p-MWCNTs) were prepared by the solvent casting method. The morphology and mechanical properties results show an improvement in strain at break for 0.25 and 0.5wt% p-MWCNTs and an increase in stiffness and elastic modulus for all compositions. Nanocomposites presented a p-MWCNTs agglomeration; however, there was a good stress transfer between PLLA and p-MWCNTs, which was confirmed by the increase in the hardness and elastic modulus. Atomic force microscopy analysis indicated an increase in roughness after nanotube addition. The in vitro biological study showed that PLLA/p-MWCNTs nanocomposites are cytocompatible with osteoblasts cells. The capacity of PLLA nanocomposites to stimulate osteogenesis was investigated by alkaline phosphatase (ALP) activity assay. Higher ALP activity was found on osteoblasts cultured on nanocomposites with 0.25 and 0.5wt% p-MWCNT compared to neat PLLA, confirming that PLLA cytocompatibility was improved on these compositions. Finally, our results showed that by a simple and inexpensive solvent casting method, it is possible to manufacture biofunctional nanocomposites devices with potential for orthopedic applications. PMID:27038896

  8. The odontogenic differentiation of human dental pulp stem cells on nanofibrous poly(L-lactic acid) scaffolds in vitro and in vivo.

    PubMed

    Wang, Jing; Liu, Xiaohua; Jin, Xiaobing; Ma, Haiyun; Hu, Jiang; Ni, Longxing; Ma, Peter X

    2010-10-01

    The aim of this study was to investigate the odontogenic differentiation of human dental pulp stem cells (DPSCs) on nanofibrous (NF)-poly(l-lactic acid) (PLLA) scaffolds in vitro and in vivo. Highly porous NF-PLLA scaffolds which mimic the architecture of collagen type I fibers were fabricated by the combination of a phase-separation technique and a porogen-leaching method. The human DPSCs were then seeded onto the scaffolds and cultured in different media for odontogenic differentiation: "Control" medium without supplements; "DXM" medium containing 10(-8)M dexamethasone (DXM), 50 microgml(-1) ascorbic acid and 5mM beta-glycerophosphate; "BMP-7+DXM" medium containing 10(-8)M DXM, 50 microgml(-1) ascorbic acid, 5mM beta-glycerophosphate plus 50 ngml(-1) bone morphogenetic protein 7 (BMP-7). For odontogenic differentiation study in vitro, alkaline phosphatase activity quantification, reverse transcription polymerase chain reaction, scanning electron microscopy, von Kossa staining and calcium content quantification were carried out. While both "DXM" medium and "BMP-7+DXM" medium induced the DPSCs to odontoblast-like cells, the "BMP-7+DXM" medium had greater inducing capacity than the "DXM" medium. Consistent with the in vitro studies, the "BMP-7+DXM" group presented more extracellular matrix and hard tissue formation than the "DXM" group after 8 weeks of ectopic implantation in nude mice. Differentiation of DPSCs into odontoblast-like cells was identified by the positive immunohistochemical staining for dentin sialoprotein. In conclusion, odontogenic differentiation of DPSCs can be achieved on NF-PLLA scaffolds both in vitro and in vivo; the combination of BMP-7 and DXM induced the odontogenic differentiation more effectively than DXM alone. The NF-PLLA scaffold and the combined odontogenic inductive factors provide excellent environment for DPSCs to regenerate dental pulp and dentin. PMID:20406702

  9. Reduction of the pro-inflammatory response by tetrandrine-loading poly(L-lactic acid) films in vitro and in vivo.

    PubMed

    Wang, Qiang-Song; Cui, Yuan-Lu; Gao, Li-Na; Guo, Yong; Li, Rui-Xin; Zhang, Xi-Zheng

    2014-11-01

    Inflammatory response of implantable biomaterials and drug delivery vehicles, driven by the reaction of macrophages to foreign body particles released from the implant, is an urgent problem to resolve. Despite this, little is known about the inflammatory molecular mechanism following the implantation of biomaterials and the evaluation of anti-inflammatory biomaterials. In this study, tetrandrine (TET) was loaded into poly (l-lactic acid) (PLLA) films to assess the anti-inflammatory effects in vitro and in vivo. The water contact angle measurement indicated the variation of hydrophilicity and the electron spectroscopy for chemical analysis (ESCA) data suggested that TET was loaded into PLLA films, which were marked as enriched with nitrogen atoms. TET-loading PLLA films had satisfactory sustained releasing behavior in salicylic acid solution with accelerating release. RAW 264.7 macrophages cultured in TET-loading PLLA films maintained lower levels of chemokines, cytokines, and enzymes involved in the inflammatory process, such as NO, TNF-α, IL-6, iNOS, COX-2 than control PLLA films, suggesting that TET-loading PLLA films could regulate the mRNA expression and protein expression to reduce the inflammatory response in macrophages. The degree of inflammatory reaction for the implant with the TET-loading PLLA films was significantly less severe than that close to control PLLA films in 4, 12 weeks after operation in rats. The present study will provide a new method to evaluate and treat the biocompatibility related to inflammatory response for implanted biomaterials and drug delivery system. PMID:24442958

  10. Synthesis and characterization of bioactive conjugated near-infrared fluorescent proteinoid-poly(L-lactic acid) hollow nanoparticles for optical detection of colon cancer

    PubMed Central

    Kolitz-Domb, Michal; Corem-Salkmon, Enav; Grinberg, Igor; Margel, Shlomo

    2014-01-01

    Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with colon cancer. Near-infrared (NIR) fluorescent nanoparticles are promising candidates for use as contrast agents for tumor detection. Using NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum: lower autofluorescence of biological tissues and lower absorbance and, consequently, deeper penetration into biomatrices. The present study describes the preparation of new NIR fluorescent proteinoid-poly(L-lactic acid) (PLLA) nanoparticles. For this purpose, a P(EF-PLLA) random copolymer was prepared by thermal copolymerization of L-glutamic acid (E) with L-phenylalanine (F) and PLLA. Under suitable conditions, this proteinoid-PLLA copolymer can self-assemble to nanosized hollow particles of relatively narrow size distribution. This self-assembly process was used for encapsulation of the NIR dye indocyanine green. The encapsulation process increases significantly the photostability of the dye. These NIR fluorescent nanoparticles were found to be stable and nontoxic. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline containing 4% human serum albumin was not detected. Tumor-targeting ligands such as peanut agglutinin and anticarcinoembryonic antigen antibodies were covalently conjugated to the surface of the NIR fluorescent P(EF-PLLA) nanoparticles, thereby increasing the fluorescent signal of tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent P(EF-PLLA) nanoparticles was demonstrated in a chicken embryo model. In future work, we plan to extend this study to a mouse model, as well as to encapsulate a cancer drug such as doxorubicin within these nanoparticles for therapeutic applications. PMID:25382975

  11. Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

    PubMed

    Hu, Yang; Ma, Shanshan; Yang, Zhuohong; Zhou, Wuyi; Du, Zhengshan; Huang, Jian; Yi, Huan; Wang, Chaoyang

    2016-04-01

    In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of d-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications. PMID:26774574

  12. Gene Cloning and Molecular Characterization of an Extracellular Poly(l-Lactic Acid) Depolymerase from Amycolatopsis sp. Strain K104-1

    PubMed Central

    Matsuda, Emiko; Abe, Naoki; Tamakawa, Hideyuki; Kaneko, Jun; Kamio, Yoshiyuki

    2005-01-01

    We have isolated a polylactide or poly(l-lactic acid) (PLA)-degrading bacterium, Amycolatopsis sp. strain K104-1, and purified PLA depolymerase (PLD) from the culture fluid of the bacterium. Here, we cloned and expressed the pld gene encoding PLD in Streptomyces lividans 1326 and characterized a recombinant PLD (rPLD) preparation. We also describe the processing mechanism from nascent PLD to mature PLD. The pld gene encodes PLD as a 24,225-Da polypeptide consisting of 238 amino acids. Biochemical and Western immunoblot analyses of PLD and its precursors revealed that PLD is synthesized as a precursor (prepro-type), requiring proteolytic cleavage of the N-terminal 35-amino-acid extension including the 26-amino-acid signal sequence and 9-residue prosequence to generate the mature enzyme of 20,904 Da. The cleavage of the prosequence was found to be autocatalytic. PLD showed about 45% similarity to many eukaryotic serine proteases. In addition, three amino acid residues, H57, D102, and S195 (chymotrypsin numbering), which are implicated in forming the catalytic triad necessary for cleavage of amide bond of substrates in eukaryotic serine proteases, were conserved in PLD as residues H74, D111, and S197. The G193 residue (chymotrypsin numbering), which is implicated in forming an oxyanion hole with residue S195 and forms an important hydrogen bond for interaction with the carbonyl group of the scissile peptide bond, was also conserved in PLD. The functional analysis of the PLD mutants H74A, D111A, and S197A revealed that residues H74, D111, and S197 are important for the depolymerase and caseinolytic activities of PLD and for cleavage of the prosequence from pro-type PLD to form the mature one. The PLD preparation had elastase activity which was not inhibited by 1 mM elastatinal, which is 10 times higher than needed for complete inhibition of porcine pancreatic elastase. The rPLD preparation degraded PLA with an average molecular mass of 220 kDa into lactic acid dimers

  13. Transient aggregation of chitosan-modified poly(d,l-lactic-co-glycolic) acid nanoparticles in the blood stream and improved lung targeting efficiency.

    PubMed

    Lee, Song Yi; Jung, Eunjae; Park, Ju-Hwan; Park, Jin Woo; Shim, Chang-Koo; Kim, Dae-Duk; Yoon, In-Soo; Cho, Hyun-Jong

    2016-10-15

    Chitosan (CS)-modified poly(d,l-lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) were prepared and their lung targetability after intravenous administration was elucidated. PLGA NPs (mean diameter: 225nm; polydispersity index: 0.11; zeta potential: -15mV), 0.2% (w/v) CS-coated PLGA NPs (CS02-PLGA NPs, mean diameter: 264nm; polydispersity index: 0.17; zeta potential: -7mV), and 0.5% (w/v) CS-coated PLGA NPs (CS05-PLGA NPs, mean diameter: 338nm; polydispersity index: 0.23; zeta potential: 12mV) were fabricated by a modified solvent evaporation method. PLGA NPs maintained their initial particle size in different media, such as human serum albumin (HSA) solution, rat plasma, and distilled water (DW), while CS05-PLGA NPs exhibited the formation of aggregates in early incubation time and disassembly of those into the NPs in late incubation time (at 24h). According to the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, the binding affinity of CS05-PLGA NPs with HSA and rat plasma was higher than that of PLGA NPs. By a near-infrared fluorescence (NIRF) imaging test in the mouse, the selective accumulation of CS05-PLGA NPs, rather than PLGA NPs, in lung tissue was demonstrated. These findings suggest that CS05-PLGA NPs can form transient aggregates in the blood stream after intravenous administration and markedly improve lung targeting efficiency, compared with PLGA NPs. PMID:27421112

  14. Calcium phosphate deposition rate, structure and osteoconductivity on electrospun poly(l-lactic acid) matrix using electrodeposition or simulated body fluid incubation

    PubMed Central

    He, Chuanglong; Jin, Xiaobing; Ma, Peter X.

    2013-01-01

    Mineralized nanofibrous scaffolds have been proposed as promising scaffolds for bone regeneration due to their ability to mimic both nanoscale architecture and chemical composition of natural bone extracellular matrix (ECM). In this study, a novel electrodeposition method was compared with an extensively explored simulated body fluid (SBF) incubation method in terms of the deposition rate, chemical composition, and morphology of calcium phosphate formed on electrospun fibrous thin matrices with a fiber diameter in the range from about 200 nm to about 1400 nm prepared using 6, 8, 10 and 12 wt% poly(l-lactic acid) (PLLA) solutions in a mixture of dichloromethane and acetone (2:1 in volume). The effects of the surface modification using the two mineralization techniques on osteoblastic cell (MC3T3-E1) proliferation and differentiation were also examined. It was found that electrodeposition was two to three orders of magnitude faster than the SBF method in mineralizing the fibrous matrices, reducing the mineralization time from about two weeks to an hour to achieve the same amounts of mineralization. The mineralization rate also varied with the fiber diameter but in opposite directions between the two mineralization methods. As a general trend, the increase of fiber diameter resulted in a faster mineralization rate for the electrodeposition method but a slower mineralization rate for the SBF incubation method. Using the electrodeposition method, one can control the chemical composition and morphology of the calcium phosphate by varying the electric deposition potential and electrolyte temperature to tune the mixture of dicalcium phosphate dihydrate (DCPD) and hydroxy apatite (HAp). Using the SBF method, one can only obtain a low crystallinity HAp. The mineralized electrospun PLLA fibrous matrices from either method similarly facilitate the proliferation and osteogenic differentiation of preosteoblastic MC3T3-E1 cells as compared to neat PLLA matrices. Therefore, the

  15. pH-Responsive Poly(D,L-lactic-co-glycolic acid) Nanoparticles with Rapid Antigen Release Behavior Promote Immune Response.

    PubMed

    Liu, Qi; Chen, Xiaoming; Jia, Jilei; Zhang, Weifeng; Yang, Tingyuan; Wang, Lianyan; Ma, Guanghui

    2015-05-26

    In the quest to treat intracellular infectious diseases and virus infection, nanoparticles (NPs) have been considered to be efficient tools for inducing potent immune responses, specifically cellular immunity. Antigen processing and presenting by antigen presenting cells (APCs) could influence immune response, especially the priming of T-cell-mediated cellular immunity. Here, we fabricated pH-responsive poly(D,L-lactic-co-glycolic acid) (PLGA) NPs with rapid antigen intracellular release behavior in APCs. The NPs, which had thin shells and large inner space, contain ammonium bicarbonate (NH4HCO3), which could regulate release in endosomes and lysosomes, acting as an antigen release promoter in dendritic cells (DCs), and were coencapsulated with antigen (ovalbumin, OVA). Hydrogen ions (H(+)) in DC endosomes and lysosomes (pH ∼5.0 and 6.5) could react with NH4HCO3 to generate NH3 and CO2, which broke NPs and released antigens. After uptake by DCs, antigens encapsulated in pH-responsive PLGA NPs could escape from lysosomes into the cytoplasm and be cross-presented. Moreover, the NPs induced up-regulation of co-stimulatory molecules and stimulated cytokine production. Mouse immunization with pH-responsive PLGA NPs induced greater lymphocyte activation, more antigen-specific CD8(+) T cells, stronger cytotoxic capacity (IFN-γ and granzyme B), enhanced antigen-specific IgG antibodies, and higher serum IgG2a/IgG1, indicating cellular immunity. The NPs also improved generation of memory T cells to protect against reinfection. Thus, pH-responsive PLGA NPs, which induced strong cellular immune responses and offered antibody protection, could be potentially useful as effective vaccine delivery and adjuvant systems for the therapy of intracellular infectious diseases and virus infection. PMID:25898266

  16. Fabrication and characterization of heparin-grafted poly-L-lactic acid-chitosan core-shell nanofibers scaffold for vascular gasket.

    PubMed

    Wang, Ting; Ji, Xuyuan; Jin, Lin; Feng, Zhangqi; Wu, Jinghang; Zheng, Jie; Wang, Hongyin; Xu, Zhe-Wu; Guo, Lingling; He, Nongyue

    2013-05-01

    Electrospun nanofibers were widely studied to be applied as potential materials for tissue engineering. A new technology to make poly-l-lactic acid/chitosan core/shell nanofibers from heterologous solution by coaxial electrospinning technique was designed for vascular gasket. Chitosan surface was cross-linked by genipin and modified by heparin. Different ratios of PLA/CS in heterologous solution were studied to optimize the surface morphology of fibers. Clean core-shell structures formed with a PLA/CS ratio at 1:3. Superior biocompatibility and mechanical properties were obtained by optimizing the core-shell structure morphology and surface cross-linking of chitosan. UE7T-13 cells grew well on the core-shell structure fibers as indicated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) results and scanning electron microscopy (SEM) images. Compared with the pure PLA fiber meshes and commercial vascular patch, PLA/CS core-shell fibers had better mechanical strength. The elastic modulus was as high as 117.18 MPa, even though the yield stress of the fibers was lower than that of the commercial vascular patch. Attachment of red blood cell on the fibers was evaluated by blood anticoagulation experiments and in vitro blood flow experiments. The activated partial thromboplastin time (APTT) and prothrombin time (PT) value from PLA/CS nanofibers were significantly longer than that of pure PLA fibers. SEM images indicated there were hardly any red blood cells attached to the fibers with chitosan coating and heparin modification. This type of fiber mesh could potentially be used as vascular gasket. PMID:23586670

  17. Effect of a bioabsorbable, super-high molecular weight poly-D,L-lactic acid plate containing recombinant human bone morphogenetic protein-2 for fracture healing

    PubMed Central

    ZHOU, NING-FENG; HUANG, YU-FENG; WANG, JIN-WU

    2015-01-01

    The aim of this study was to investigate the effect of a bioabsorbable, super-high molecular weight poly-D,L-lactic acid (PDLLA) plate exhibiting the sustained release of recombinant human bone morphogenetic protein-2 (rhBMP-2) (PDLLA-rhBMP-2) on the treatment of fracture with internal fixation. A total of 32 New Zealand rabbits were randomly allocated to one of four groups (2, 4, 8 and 12 weeks), and a 2.5-mm middle ulnar osteotomy was performed bilaterally. The right side (experimental side) was fixed internally with PDLLA-rhBMP-2, and the left side (control side) was fixed with a normal PDLLA plate. At 2, 4, 8 and 12 weeks after surgery, the gross pathology of the ulnas was examined and radiographic, histological and computer image analyses were performed. The results demonstrated that the ulna fractures were fixed stably with the two bioactive plates at 2, 4, 8 and 12 weeks after surgery. At the 8-week time-point, 7 rabbits exhibited good healing at the osteotomy site on the experimental side. At 12 weeks after surgery, 8 rabbits exhibited good healing at the osteotomy site on both sides, but the experimental side showed enhanced compatibility between the plates and surrounding tissue, faster bone formation, a greater bone regeneration mass and better medullary canal structure compared with the control side. In conclusion, PPLLA-rhBMP-2 may be effectively used to treat fracture or nonunion at a non-weight-bearing site. PMID:26640559

  18. Fabrication and in vitro release behavior of a novel antibacterial coating containing halogenated furanone-loaded poly(L-lactic acid) nanoparticles on microarc-oxidized titanium

    PubMed Central

    Cheng, Yicheng; Wu, Jiang; Gao, Bo; Zhao, Xianghui; Yao, Junyan; Mei, Shenglin; Zhang, Liang; Ren, Huifang

    2012-01-01

    Background Dental implants have become increasingly common for the management of missing teeth. However, peri-implant infection remains a problem, is usually difficult to treat, and may lead eventually to dental implant failure. The aim of this study was to fabricate a novel antibacterial coating containing a halogenated furanone compound, ie, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone (BBF)-loaded poly(L-lactic acid) (PLLA) nanoparticles on microarc-oxidized titanium and to evaluate its release behavior in vitro. Methods BBF-loaded PLLA nanoparticles were prepared using the emulsion solvent-evaporation method, and the antibacterial coating was fabricated by cross-linking BBF-loaded PLLA nanoparticles with gelatin on microarc-oxidized titanium. Results The BBF-loaded PLLA nanoparticles had a small particle size (408 ± 14 nm), a low polydispersity index (0.140 ± 0.008), a high encapsulation efficiency (72.44% ± 1.27%), and a fine spherical shape with a smooth surface. The morphology of the fabricated antibacterial coating showed that the BBF-loaded PLLA nanoparticles were well distributed in the pores of the microarc oxidation coating, and were cross-linked with each other and the wall pores by gelatin. The release study indicated that the antibacterial coating could achieve sustained release of BBF for 60 days, with a slight initial burst release during the first 4 hours. Conclusion The novel antibacterial coating fabricated in this study is a potentially promising method for prevention of early peri-implant infection. PMID:23152682

  19. The Effect of Hydrolysis on the Mechanical Properties of Injection-Molded Poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Kobayashi, Satoshi; Todo, Mitsugu

    Injection molded bulk-shape Poly (L-lactide) (PLLA) specimens were hydrolyzed in the phosphate buffered solution and the mechanical properties were evaluated after the hydrolysis tests. In order to evaluated the effect of crystallinity on the hydrolysis, specimens were annealed with 70 and 130°C for 24h. Hydrolysis tests were conducted with soaking the specimens in the phosphate buffered solution (pH 7.4) in an incubator where temperature was kept as 37°C. Vickers hardness was not influenced by hydrolysis until 30 days. Tensile tests results, however, indicated the strength reduction with hydrolysis. From the appearance inspection, whitened regions were observed at the inner of the specimen. These results indicated the bulk erosion with accelerated inside erosion occurred.

  20. Evaluation of the novel three-dimensional porous poly (L-lactic acid)/nano-hydroxyapatite composite scaffold.

    PubMed

    Huang, Jianghong; Xiong, Jianyi; Liu, Jianquan; Zhu, Weimin; Chen, Jielin; Duan, Li; Zhang, Jufeng; Wang, Daping

    2015-01-01

    To determine the optimal ratio of nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) in the novel three-dimensional porous PLLA/n-HA composite scaffolds, low-temperature rapid prototyping technology was employed to fabricate the composite materials with different n-HA contents. Mechanical properties and degradation behaviors of the composites were examined, and the scaffold microstructure and n-HA dispersion were observed by scanning electron microscope (SEM). Mechanical tests demonstrated that the tensile strength of the composite material gradually decreased with an increase in n-HA content. When the n-HA content reached 20 wt%, the bending strength of the composite material peaked at 138.5 MPa. SEM images demonstrated that the optimal content of n-HA was 20 wt% as the largest interconnected pore size that can be seen, with a porosity as high as 80%. In vitro degradation experiments demonstrated that the pH value of the material containing solution gradually decreased in a time-dependent manner, with a simultaneous weakening of the mechanical properties. In vitro study using rat osteoblast cells showed that the composite scaffolds were biocompatible; the 20 wt% n-HA scaffold offered particular improvement to rat osteoblast cell adhesion and proliferation compared to other compositions. It was therefore concluded that 20 wt% n-HA is the optimal nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) ratio, with promise for bone tissue engineering. PMID:26405972

  1. Resveratrol-Loaded Nanoparticles Based on Poly(epsilon-caprolactone) and Poly(d,l-lactic-co-glycolic acid)–Poly(ethylene glycol) Blend for Prostate Cancer Treatment

    PubMed Central

    Sanna, Vanna; Siddiqui, Imtiaz Ahmad; Sechi, Mario; Mukhtar, Hasan

    2014-01-01

    Nanoencapsulation of antiproliferative and chemopreventive phytoalexin trans-resveratrol (RSV) is likely to provide protection against degradation, enhancement of bioavailability, improvement in intracellular penetration and control delivery. In this study, polymeric nanoparticles (NPs) encapsulating RSV (nano-RSV) as novel prototypes for prostate cancer (PCa) treatment were designed, characterized and evaluated using human PCa cells. Nanosystems, composed of a biocompatible blend of poly(epsilon-caprolactone) (PCL) and poly(d,l-lactic-co-glycolic acid)-poly(ethylene glycol) conjugate (PLGA-PEG-COOH), were prepared by a nanoprecipitation method, and characterized in terms of morphology, particle size and zeta potential, encapsulation efficiency, thermal analyses, and in vitro release studies. Cellular uptake of NPs was then evaluated in PCa cell lines DU-145, PC-3, and LNCaP using confocal fluorescence microscopy, and antiproliferative efficacy was assessed using MTT assay. With encapsulation efficiencies ranging from 74% to 98%, RSV was successfully loaded in PCL:PLGA-PEG-COOH NPs, which showed an average diameter of 150 nm. NPs were able to control the RSV release at pH 6.5 and 7.4, mimicking the acidic tumoral microenvironment and physiological conditions, respectively, with only 55% of RSV released within 7 h. In gastrointestinal simulated fluids, NPs released about 55% of RSV in the first 2 h in acidic medium, and their total RSV content within the subsequent 5 h at pH 7.4. Confocal fluorescence microscopy observations revealed that NPs were efficiently taken up by PCa cell lines. Furthermore, nano-RSV significantly improved the cytotoxicity compared to that of free RSV toward all three cell lines, at all tested concentrations (from 10 µM to 40 µM), proving a consistent sensitivity toward both the androgen-independent DU-145 and hormone-sensitive LNCaP cells. Our findings support the potential use of developed nanoprototypes for the controlled delivery of

  2. Experimental Embolization of Rabbit Renal Arteries to Compare the Effects of Poly L-Lactic Acid Microspheres With and Without Epirubicin Release Against Intraarterial Injection of Epirubicin

    SciTech Connect

    Fujiwara, Kazuhisa; Hayakawa, Katsumi; Nagata, Yasushi; Hiraoka, Masahiro; Nakamura, Tatsuo; Shimizu, Yoshihiko; Ikada, Yoshito

    2000-03-15

    Purpose: We performed a basic investigation using white rabbits of the sustained release and embolizing effects of poly L-lactic acid microspheres (PLA) to determine their usefulness for chemoembolization.Methods: Fifteen male Japanese white rabbits were used. Sustained release of an embolizing material, EPI-PLA was accomplished with 1 mg of PLA containing 0.03 mg of epirubicin hydrochloride (EPI). Embolization with 50 mg of PLA (total dose of EPI 1.5 mg) was performed after the renal artery of the rabbits was selected (Chemo-TAE group). A group in which a bolus of 1.5 mg EPI alone was injected through the renal artery (TAI group) was established as a control group. Furthermore, a group in which embolization was performed with 50 mg of PLA alone (TAE group) was also established. These three groups, each consisting of five rabbits, were compared.Results: Blood EPI levels were serially measured. The blood EPI level in the TAI group rapidly reached a peak more than 30 min after injection, then decreased to almost zero 24 hr after injection. In the Chemo-TAE group, the blood EPI level was transiently increased 30 min after embolization, but remained low thereafter until 24 hr after embolization. EPI levels in kidney tissue isolated 24 hr after embolization were measured. In the Chemo-TAE group, the tissue EPI level was significantly higher than that in the TAI group. When isolated kidneys were macroscopically and histologically examined, atrophy of the entire embolized kidney, as well as infarction and necrosis in the renal cortex, were observed in both the TAE group and the Chemo-TAE group. However, there were no such findings in the TAI group. The area of the infarction in the renal cortex did not significantly differ between the Chemo-TAE group and the TAE group; however, there was vascular injury in the Chemo-TAE group and none in the TAE group.Conclusion: It was demonstrated that EPI-PLA, a chemoembolizing material, maintained high local concentrations of the

  3. Experimental embolization of rabbit renal arteries to compare the effects of poly L-lactic acid microspheres with and without epirubicin release against ntraarterial injection of epirubicin

    SciTech Connect

    Fujiwara, Kazuhisa; Hayakawa, Katsumi; Nagata, Yasushi; Hiraoka, Masahiro; Nakamura, Tatsuo; Shimizu, Yoshihiko; Ikada, Yoshito

    2000-05-15

    Purpose: We performed a basic investigation using white rabbits of the sustained release and embolizing effects of poly L-lactic acid microspheres (PLA) to determine their usefulness for chemoembolization.Methods: Fifteen male Japanese white rabbits were used. Sustained release of an embolizing material, EPI-PLA was accomplished with l m g of PLA containing 0.03 mg of epirubicin hydrochloride (EPI). Embolization with 50 mg of PLA (total dose of EPI l.5 mg) was performed after the renal artery of the rabbits was selected (Chemo-TAE group). A group in which a bolus of 1.5 mg EPI alone was injected through the renal artery (TAI group) was established as a control group. Furthermore, a group in which embolization was performed with 50 mg of PLA alone (TAE group) was also established. These three groups, each consisting of five rabbits, were compared.Results: Blood EPI levels were serially measured. The blood EPI level in the TAI group rapidly reached a peak more than 30 min after injection, then decreased to almost zero 24 hr after injection. In the Chemo-TAE group, the blood EPI level was transiently increased 30 min after embolization, but remained low thereafter until 24 hr after embolization. EPI levels in kidney tissue isolated 24 hr after embolization were measured. In the Chemo-TAE group, the tissue EPI level was significantly higher than that in the TAI group. When isolated kidneys were macroscopically and histologically examined, atrophy of the entire embolized kidney, as well as infarction and necrosis in the renal cortex, were observed in both the TAE group and the Chemo-TAE group. However, there were no such findings in the TAI group. The area of the infarction in the renal cortex did not significantly differ between the Chemo-TAE group and the TAE group; however, there was vascular injury in the Chemo-TAE group and none in the TAE group.Conclusion: It was demonstrated that EPI-PLA, a chemo-embolizing material, maintained high local concentrations of the

  4. Humidity-dependent compression-induced glass transition of the air–water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA)

    SciTech Connect

    Kim, Hyun Chang; Lee, Hoyoung; Jung, Hyunjung; Choi, Yun -Hwa; Meron, Mati; Lin, Binhua; Bang, Joona; Won, You -Yeon

    2015-08-26

    Constant rate compression isotherms of the air–water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA)show a distinct feature of an exponential increase in surface pressure in the high surface polymer concentration regime. We have previously demonstrated that this abrupt increase in surface pressure is linked to the glass transition of the polymer film, but the detailed mechanism of this process is not understood. In order to obtain a molecular-level understanding of this behavior, we performed extensive characterizations of the surface mechanical, structural and rheological properties of Langmuir PLGA films at the air–water interface, using combined experimental techniques including the Langmuir film balance, X-ray reflectivity and double-wall-ring interfacial rheometry methods.

  5. Production of L-lactic Acid from Biomass Wastes Using Scallop Crude Enzymes and Novel Lactic Acid Bacterium

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Mitsunori; Nakamura, Kanami; Nakasaki, Kiyohiko

    In the present study, biomass waste raw materials including paper mill sludge, bamboo, sea lettuce, and shochu residue (from a distiller) and crude enzymes derived from inedible and discarded scallop parts were used to produce L-lactic acid for the raw material of biodegradable plastic poly-lactic acid. The activities of cellulase and amylase in the crude enzymes were 22 and 170units/L, respectively, and L-lactic acid was produced from every of the above mentioned biomass wastes, by the method of liquid-state simultaneous saccharification and fermentation (SSF) . The L-lactic acid concentrations produced from sea lettuce and shochu residue, which contain high concentration of starch were 3.6 and 9.3g/L, respectively, and corresponded to greater than 25% of the conversion of glucans contained in these biomass wastes. Furthermore, using the solid state SSF method, concentrations as high as 13g/L of L-lactic acid were obtained from sea lettuce and 26g/L were obtained from shochu residue.

  6. Ketoprofen-poly(D,L-lactic-co-glycolic acid) microspheres: influence of manufacturing parameters and type of polymer on the release characteristics.

    PubMed

    Gabor, F; Ertl, B; Wirth, M; Mallinger, R

    1999-01-01

    The effect of manufacturing parameters on the size and drug-loading of ketoprofen-containing biodegradable and biocompatible poly(DL-lactic-co-glycolic acid) (PLGA) microspheres prepared by the solvent evaporation method was investigated. For both drug-free and drug-loaded microspheres, smaller microspheres with a narrower size distribution were obtained when the stirring rate or the volume of the organic phase was increased. Incorporation of ketoprofen was found to increase with increasing volume of the organic phase and decreasing pH of the aqueous phase, but was independent of the acidity and the inherent viscosity of the PLGA used. The biphasic release profile of ketoprofen from the microspheres was dependent on the type of PLGA as well as the size and drug-loading, two parameters governed by the manufacturing process. The first burst effect was found to increase with the drug content, reduction of size of the microspheres and increasing inherent viscosity of the matrix, whereas acidity of the PLGA had no effect on the release of this acidic drug. A vigorous first burst effect was associated with reduced sustained delivery of ketoprofen, the rate of the delayed release phase being dependent on the inherent viscosity of the matrix, the size, the payload and the pH during preparation of the microspheres. Thus, by selection of the manufacturing parameters and the type of PLGA, it is possible to design a controlled drug delivery system for the prolonged release of ketoprofen, improving therapy by possible reduction of time intervals between peroral administration and reduction of local gastrointestinal side effects. PMID:9972498

  7. Aesthetic recovery of alveolar atrophy following autogenous onlay bone grafting using interconnected porous hydroxyapatite ceramics (IP-CHA) and resorbable poly-L-lactic/polyglycolic acid screws: case report

    PubMed Central

    2014-01-01

    Background Onlay bone grafting techniques have some problems related to the limited volume of autogenous grafted bone and need for surgery to remove bone fixing screws. Here, we report a case of horizontal alveolar ridge atrophy following resection of a maxillary bone cyst, in which autogenous onlay bone grafting with interconnected porous hydroxyapatite ceramics (IP-CHA) and bioresorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) screws was utilized. Case presentation A 51-year-old man had aesthetic complications related to alveolar atrophy following maxillary bone cyst extraction. We performed onlay grafting for aesthetic alveolar bone recovery using IP-CHA to provide adequate horizontal bone volume and PLLA-PGA screws for bone fixing to avoid later damage to host bone during surgical removal. During the operation, an autogenous cortical bone block was collected from the ramus mandibular and fixed to the alveolar ridge with PLLA-PGA screws, then the gap between the bone block and recipient bone was filled with a granular type of IP-CHA. Post-surgery orthopantomograph and CT scan findings showed no abnormal resorption of the grafted bone, and increased radiopacity, which indicated new bone formation in the area implanted with IP-CHA. Conclusion Our results show that IP-CHA and resorbable PLLA-PGA screws are useful materials for autogenous onlay bone grafting. PMID:24889647

  8. In Vitro and in Vivo Studies of Novel Poly(D,L-lactic acid), Superhydrophilic Carbon Nanotubes, and Nanohydroxyapatite Scaffolds for Bone Regeneration.

    PubMed

    Siqueira, Idalia A W B; Corat, Marcus Alexandre F; Cavalcanti, Bruno das Neves; Ribeiro Neto, Wilson Alves; Martin, Airton Abrahao; Bretas, Rosario Elida Suman; Marciano, Fernanda Roberta; Lobo, Anderson Oliveira

    2015-05-13

    Poly(D,L-lactide acid, PDLLA) has been researched for scaffolds in bone regeneration. However, its hydrophobocity and smooth surface impedes its interaction with biological fluid and cell adhesion. To alter the surface characteristics, different surface modification techniques have been developed to facilitate biological application. The present study compared two different routes to produce PDLLA/superhydrophilic vertically aligned carbon nanotubes:nanohydroxyapatite (PDLLA/VACNT-O:nHAp) scaffolds. For this, we used electrodeposition and immersion in simulated body fluid (SBF). Characterization by goniometry, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy confirmed the polymer modifications, the in vitro bioactivity, and biomineralization. Differential scanning calorimetry and thermal gravimetric analyses showed that the inclusion of VACNT-O:nHA probably acts as a nucleating agent increasing the crystallization rate in the neat PDLLA without structural alteration. Our results showed the formation of a dense nHAp layer on all scaffolds after 14 days of immersion in SBF solution; the most intense carbonated nHAp peaks observed in the PDLLA/VACNT-O:nHAp samples suggest higher calcium precipitation compared to the PDLLA control. Both cell viability and alkaline phosphatase assays showed favorable results, because no cytotoxic effects were present and all produced scaffolds were able to induce detectable mineralization. Bone defects were used to evaluate the bone regeneration; the confocal Raman and histological results confirmed high potential for bone applications. In vivo study showed that the PDLLA/VACNT-O:nHAp scaffolds mimicked the immature bone and induced bone remodeling. These findings indicate surface improvement and the applicability of this new nanobiomaterial for bone regenerative medicine. PMID:25899398

  9. Wireless Biosensor System for Real-Time l-Lactic Acid Monitoring in Fish

    PubMed Central

    Hibi, Kyoko; Hatanaka, Kengo; Takase, Mai; Ren, Huifeng; Endo, Hideaki

    2012-01-01

    We have developed a wireless biosensor system to continuously monitor l-lactic acid concentrations in fish. The blood l-lactic acid level of fish is a barometer of stress. The biosensor comprised Pt-Ir wire (φ0.178 mm) as the working electrode and Ag/AgCl paste as the reference electrode. Lactate oxidase was immobilized on the working electrode using glutaraldehyde. The sensor calibration was linear and good correlated with l-lactic acid levels (R = 0.9959) in the range of 0.04 to 6.0 mg·dL−1. We used the eyeball interstitial sclera fluid (EISF) as the site of sensor implantation. The blood l-lactic acid levels correlated closely with the EISF l-lactic acid levels in the range of 3 to 13 mg·dL−1 (R = 0.8173, n = 26). Wireless monitoring of l-lactic acid was performed using the sensor system in free-swimming fish in an aquarium. The sensor response was stable for over 60 h. Thus, our biosensor provided a rapid and convenient method for real-time monitoring of l-lactic acid levels in fish. PMID:22778641

  10. Delivery of an inactivated avian influenza virus vaccine adjuvanted with poly(D,L-lactic-co-glycolic acid) encapsulated CpG ODN induces protective immune responses in chickens.

    PubMed

    Singh, Shirene M; Alkie, Tamiru N; Nagy, Éva; Kulkarni, Raveendra R; Hodgins, Douglas C; Sharif, Shayan

    2016-09-14

    In poultry, systemic administration of commercial vaccines consisting of inactivated avian influenza virus (AIV) requires the simultaneous delivery of an adjuvant (water-in-oil emulsion). These vaccines are often limited in their ability to induce quantitatively better local (mucosal) antibody responses capable of curtailing virus shedding. Therefore, more efficacious adjuvants with the ability to provide enhanced immunogenicity and protective anti-AIV immunity in chickens are needed. While the Toll-like receptor (TLR) 21 agonist, CpG oligodeoxynucleotides (ODNs) has been recognized as a potential vaccine adjuvant in chickens, poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles, successfully tested as vaccine delivery systems in other species, have not been extensively explored. The present study, therefore, assessed both systemic and mucosal antibody-mediated responses following intramuscular vaccination (administered at 7 and 21days post-hatch) of chickens with PLGA encapsulated H9N2 AIV plus encapsulated CpG ODN 2007 (CpG 2007), and nonencapsulated AIV plus PLGA encapsulated CpG 2007 vaccine formulations. Virus challenge was performed at 2weeks post-secondary vaccination using the oculo-nasal route. Our results showed that chickens vaccinated with the nonencapsulated AIV vaccine plus PLGA encapsulated CpG 2007 developed significantly higher systemic IgY and local (mucosal) IgY antibodies as well as haemagglutination inhibition antibody titres compared to PLGA encapsulated AIV plus encapsulated CpG 2007 vaccinated chickens. Furthermore, chickens that received CpG 2007 as an adjuvant in the vaccine formulation had antibodies exhibiting higher avidity indicating that the TLR21-mediated pathway may enhance antibody affinity maturation qualitatively. Collectively, our data indicate that vaccination of chickens with nonencapsulated AIV plus PLGA encapsulated CpG 2007 results in qualitatively and quantitatively augmented antibody responses leading to a reduction in

  11. Hydroxyapatite surface modified by L-lactic acid and its subsequent grafting polymerization of L-lactide.

    PubMed

    Qiu, Xueyu; Hong, Zhongkui; Hu, Junli; Chen, Li; Chen, Xuesi; Jing, Xiabin

    2005-01-01

    A new method of surface modification of hydroxyapatite nanoparticles (n-HA) by surface grafting reaction of l-lactic acid and ring-opening polymerization of l-lactide (LLA) was developed. Two modified HA nanoparticles were obtained: HA modified by l-lactic acid (l-HA) and HA grafting with poly(l-lactide) (PLLA; p-HA). The modified surface of n-HA was attested by Fourier transformation infrared, (31)P MAS NMR, and thermal gravimetric analysis. The results showed that l-lactic acid could be easily grafted onto the n-HA surface by forming a Ca carboxylate bond and initiated by the hydroxyl group of the grafted l-lactic acid and LLA could be graft-polymerized onto the n-HA surface in the presence of stannous octanoate. The highest grafting amounts of l-lactic acid and PLLA were about 33 and 22 wt %, respectively. The modified HA/PLLA composites showed good mechanical properties and uniform microstructure. The tensile strength and modulus of the p-HA/PLLA composite containing 15 wt % of p-HA were 67 MPa and 2.1 GPa, respectively, while those of the n-HA/PLLA composites were 45 MPa and 1.7 GPa, respectively. The elongation at the break of the l-HA/PLLA composite containing 15 wt % l-HA could reach 44%, in comparison with 6.5% of the n-HA/PLLA composites containing 15 wt % n-HA. PMID:15877333

  12. An integrated bioconversion process for the production of L-lactic acid from starchy feedstocks

    SciTech Connect

    Tsai, S.P.; Moon, S.H.

    1997-07-01

    The potential market for lactic acid as the feedstock for biodegradable polymers, oxygenated chemicals, and specialty chemicals is significant. L-lactic acid is often the desired enantiomer for such applications. However, stereospecific lactobacilli do not metabolize starch efficiently. In this work, Argonne researchers have developed a process to convert starchy feedstocks into L-lactic acid. The processing steps include starch recovery, continuous liquefaction, and simultaneous saccharification and fermentation. Over 100 g/L of lactic acid was produced in less than 48 h. The optical purity of the product was greater than 95%. This process has potential economical advantages over the conventional process.

  13. Use of wastewater sludge as a raw material for production of L-lactic acid

    SciTech Connect

    Nakasaki, Kiyohiko; Akakura, Naoki; Adachi, Tomohiko; Akiyama, Tetsuo

    1999-01-01

    This study utilizes wastewater sludges to produce L-lactic acid, a precursor of biodegradable plastic. The high concentrations of cellulose contained in the sludge, derived from a paper manufacturing facility, have been found to be convertible to L-lactic acid at a rate as high as 6.91 g/L. To achieve such a high conversion rate, the sludge must be pretreated with cellulase. This pretreatment includes inoculation of the sludge with lactic acid bacteria, strain LA1, after the sludge has been subjected to enzymatic hydrolysis.

  14. The effect of temperature on L-lactic acid production and metabolite distribution of Lactobacillus casei.

    PubMed

    Qin, Hao; Gong, Sai-Sai; Ge, Xiang-Yang; Zhang, Wei-Guo

    2012-01-01

    The effect of temperature on the growth and L-lactic acid production of Lactobacillus casei G-03 was investigated in a 7-L bioreactor. It was found that the maximum specific growth rate (0.27 hr⁻¹) and L-lactic acid concentration (160.2 g L⁻¹) were obtained at a temperature of 41°C. Meanwhile, the maximum L-lactic acid yield, productivity, and dry cell weight were up to 94.1%, 4.44 g L⁻¹ hr⁻¹, and 4.30 g L⁻¹, respectively. At lower or higher temperature, the Lactobacillus casei G-03 showed lower acid production and biomass. Moreover, the main metabolite distribution of strain G-03 response to variations in temperatures was studied. The results suggested that temperature has a remarkable effect on metabolite distribution, and the maximum carbon flux toward lactic acid at the pyruvate node was obtained at 41°C, which had the minimum carbon flux toward acetic acid. PMID:23030467

  15. A highly sensitive electrochemical biosensor based on zinc oxide nanotetrapods for L-lactic acid detection.

    PubMed

    Lei, Yang; Luo, Ning; Yan, Xiaoqin; Zhao, Yanguang; Zhang, Gong; Zhang, Yue

    2012-06-01

    An amperometric biosensor based on zinc oxide (ZnO) nanotetrapods was designed to detect L-lactic acid. The lactate oxidase was immobilized on the surface of ZnO nanotetrapods by electrostatic adsorption. Unlike traditional detectors, the special four-leg individual ZnO nanostructure, as an adsorption layer, provides multiterminal charge transfer channels. Furthermore, a large amount of ZnO tetrapods are randomly stacked to form a three-dimensional network naturally that facilitates the exchange of electrons and ions in the phosphate buffer solution. Utilizing amperometric response measurements, the prepared ZnO nanotetrapod L-lactic acid biosensor displayed a detection limit of 1.2 μM, a low apparent Michaelis-Menten constant of 0.58 mM, a high sensitivity of 28.0 μA cm(-2) mM(-1) and a good linear relationship in the range of 3.6 μM-0.6 mM for the L-lactic acid detection. This study shows that the biosensor based on ZnO tetrapod nanostructures is highly sensitive and able to respond rapidly in detecting lactic acid. PMID:22538963

  16. Highly efficient production of optically pure l-lactic acid from corn stover hydrolysate by thermophilic Bacillus coagulans.

    PubMed

    Ma, Kedong; Hu, Guoquan; Pan, Liwei; Wang, Zichao; Zhou, Yi; Wang, Yanwei; Ruan, Zhiyong; He, Mingxiong

    2016-11-01

    A thermophilic strain Bacillus coagulans (NBRC 12714) was employed to produce l-lactic acid from corn stover hydrolysate in membrane integrated continuous fermentation. The strain NBRC 12714 metabolized glucose and xylose by the Embden-Meyerhof-Parnas pathway (EMP) and the pentose phosphate pathway (PPP), producing l-lactic acid with optical purity >99.5%. The overall l-lactic acid titer of 92g/l with a yield of 0.91g/g and a productivity of 13.8g/l/h were achieved at a dilution rate of 0.15h(-1). The productivity obtained was 1.6-fold than that of conventional continuous fermentation without cell recycling, and also was the highest among the relevant studies ever reported. These results indicated that the process developed had great potential for economical industrial production of l-lactic acid from lignocellulosic biomass. PMID:27479802

  17. Improvement of l-lactic acid productivity from sweet sorghum juice by repeated batch fermentation coupled with membrane separation.

    PubMed

    Wang, Yong; Meng, Hongyu; Cai, Di; Wang, Bin; Qin, Peiyong; Wang, Zheng; Tan, Tianwei

    2016-07-01

    In order to efficiently produce l-lactic acid from non-food feedstocks, sweet sorghum juice (SSJ), which is rich of fermentable sugars, was directly used for l-lactic acid fermentation by Lactobacillus rhamnosus LA-04-1. A membrane integrated repeated batch fermentation (MIRB) was developed for productivity improvement. High-cell-density fermentation was achieved with a final cell density (OD620) of 42.3, and the CCR effect was overcomed. When SSJ (6.77gL(-1) glucose, 4.51gL(-1) fructose and 50.46gL(-1) sucrose) was used as carbon source in MIRB process, l-lactic acid productivity was increased significantly from 1.45gL(-1)h(-1) (batch 1) to 17.55gL(-1)h(-1) (batch 6). This process introduces an effective way to produce l-lactic acid from SSJ. PMID:27023384

  18. L (+)-lactic acid production by pellet-form Rhizopus oryzae NRRL 395 on biodiesel crude glycerol

    PubMed Central

    2013-01-01

    Background Given its availability and low price, glycerol derived from biodiesel industry has become an ideal feedstock for the production of fuels and chemicals. A solution to reduce the negative environmental problems and the cost of biodiesel is to use crude glycerol as carbon source for microbial growth media in order to produce valuable organic chemicals. In the present paper, crude glycerol was used as carbon substrate for production of L (+)-lactic acid using pelletized fungus R. oryzae NRRL 395 on batch fermentation. More, the experiments were conducted on media supplemented with inorganic nutrients and lucerne green juice. Results Crude and pure glycerols were first used to produce the highest biomass yield of R. oryzae NRRL 395. An enhanced lactic acid production then followed up using fed-batch fermentation with crude glycerol, inorganic nutrients and lucerne green juice. The optimal crude glycerol concentration for cultivating R. oryzae NRRL 395 was 75 g l-1, which resulted in a fungal biomass yield of 0.72 g g-1 in trial without lucerne green juice addition and 0.83 g g-1 in trial with lucerne green juice. The glycerol consumption rate was 1.04 g l-1 h-1 after 48 h in trial with crude glycerol 75 g l-1 while in trial with crude glycerol 10 g l-1 the lowest rate of 0.12 g l-1 h-1 was registered. The highest L (+)-lactic acid yield (3.72 g g-1) was obtained at the crude glycerol concentration of 75 g l-1 and LGJ 25 g l-1, and the concentration of lactic acid was approximately 48 g l-1. Conclusions This work introduced sustainable opportunities for L (+)-lactic acid production via R. oryzae NRRL 395 fermentation on biodiesel crude glycerol media. The results showed good fungal growth on crude glycerol at 75 g l-1 concentration with lucerne green juice supplementation of 25 g l-1. Lucerne green juice provided a good source of nutrients for crude glycerol fermentation, without needs for supplementation with inorganic nutrients

  19. Poly (D,L-lactic-co-glycolide) nanoparticles for the improved therapeutic efficacy of all-trans-retinoic acid: a study of acute myeloid leukemia (AML) cell differentiation in vitro.

    PubMed

    Simon, Aswathy Mary; Jagadeeshan, Sankar; Abraham, Emimol; Akhilandeshwaran, Ashalatha; Pillai, Jisha J; Kumar, Nisha Asok; Sivakumari, Asha Nair; Kumar, Gopalakrishnapillai Sankaramangalam Vinod

    2012-09-01

    All-trans-retinoic acid reverses malignant cell growth and induces cell differentiation and apoptosis. Poor aqueous solubility and uncertain bioavailability are the limiting factors for using all-trans-retinoic acid for tumor therapy. The objective of present study was to encapsulate the hydrophobic drug all-trans-retinoic acid in the polymer poly (lactide-coglycolide). The encapsulation was expected to improve the bioavailability and solubility of the drug. Oil in water single emulsion solvent evaporation technique used for the preparation efficiently encapsulated about 60% of the drug. The drug release profile showed a biphasic pattern with 70% of the drug being released in first 48 hrs and the residual drug showing a slow controlled release reaching up to 8 days. The particle size of 150-200 nm as determined with TEM was ideal for tumor targeting. All-trans-retinoic acid loaded nanoparticles were efficient to induce differentiation and blocked the proliferation of HL-60 cells invitro. These studies also revealed that the dosage of drug required for the therapeutic effects have been reduced efficiently. Our studies thereby demonstrate that Poly (lactide-co-glycolide) based nanoparticles may be efficient for parenteral administration of the drug. PMID:22741806

  20. Effects of pretreatment on the microbial community and l-lactic acid production in vinasse fermentation.

    PubMed

    Liu, Jianguo; Wang, Qunhui; Wang, Shuang; Sun, Xiaohong; Ma, Hongzhi; Tushiro, Yukihiro

    2012-12-15

    Microwave-alkali and steam-alkali coupled pretreatments were carried out to improve the yield and optical purity of l-lactic acid produced using vinasse fermentation. Lactobacillus casei was inoculated into the system to initiate fermentation. Polymerase chain reaction denaturing gradient gel electrophoresis was used to analyze the microbial community during fermentation with and without the pretreatments. The original bacterial genus in vinasse was essentially inactivated, whereas L. casei became the dominant genus after 24h of fermentation. The system subjected to microwave-alkali coupled pretreatment released more reducing sugars and produced more lactic acid (up to 30.32g/L), which is twice that without pretreatment. In addition, the proportion of lactic acid in the organic acids also increased. The optical purity of the l-lactic acid produced under the microwave-alkali coupled pretreatment reached 91%, which is 2% higher than that under the steam-alkali coupled pretreatment and 7% higher than that under the control conditions. Therefore, the microwave-alkali coupled pretreatment is an effective method for the highly efficient bioconversion of vinasse into bioenergy. PMID:22959862

  1. Electrochemical L-lactic acid sensor based on immobilized ZnO nanorods with lactate oxidase.

    PubMed

    Ibupoto, Zafar Hussain; Shah, Syed Muhammad Usman Ali; Khun, Kimleang; Willander, Magnus

    2012-01-01

    In this work, fabrication of gold coated glass substrate, growth of ZnO nanorods and potentiometric response of lactic acid are explained. The biosensor was developed by immobilizing the lactate oxidase on the ZnO nanorods in combination with glutaraldehyde as a cross linker for lactate oxidase enzyme. The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor. We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10(-4)-1 × 10(0) mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade. In addition, the proposed biosensor showed fast response time less than 10 s, a good selectivity towards l-lactic acid in presence of common interfering substances such as ascorbic acid, urea, glucose, galactose, magnesium ions and calcium ions. The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks. PMID:22736960

  2. Efficient production of l-lactic acid using co-feeding strategy based on cane molasses/glucose carbon sources.

    PubMed

    Xu, Ke; Xu, Ping

    2014-02-01

    L-Lactic acid is an important platform chemical, which ought to be produced under cost control to meet its huge demand. Cane molasses, a waste from sugar manufacturing processes, is hopeful to be utilized as a cheap carbon source for L-lactic acid fermentation. Considering that cane molasses contains nutrients and hazardous substances, efficient production of L-lactic acid was developed by using a co-feeding strategy based on the utilization of cane molasses/glucose carbon sources. Based on the medium optimization with response surface method, 168.3g/L L-lactic acid was obtained by a Bacillus coagulans strain H-1 after 78h fed-batch fermentation, with a productivity of 2.1g/Lh and a yield of 0.88g/g. Since cane molasses is a feasible carbon source, the co-feeding fermentation might be a promising alternative for the economical production of L-lactic acid. PMID:24333698

  3. Production of high optical purity l-lactic acid from waste activated sludge by supplementing carbohydrate: effect of temperature and pretreatment time.

    PubMed

    Jian, Qiwei; Li, Xiang; Chen, Yinguang; Liu, Yanan; Pan, Yin

    2016-10-01

    It has been widely accepted that the most environmentally beneficial way to treat waste activated sludge (WAS), the byproduct of municipal wastewater treatment plant, is to recover the valuable organic acid. However, the bio-conversion of lactic acid, one of the high added-value chemical, is seldom reported from WAS fermentation. In this paper, l-lactic acid was observed dominant in the WAS fermentation liquid with carbohydrate addition at ambient temperature. Furthermore, the effect of temperature on l-lactic acid and d-lactic acid production was fully discussed: two isomers were rapidly produced and consumed up in one day at mesophilic condition; and almost optically pure l-lactic acid was generated at thermophilic condition, yet time-consuming with yield of l-lactic acid enhancing by 52.9% compared to that at ambient temperature. The study mechanism showed that mesophilic condition was optimal for both production and consumption of l-lactic acid and d-lactic acid, while consumption of l-lactic acid and production of d-lactic acid were severely inhibited at thermophilic condition. Therefore, by maintaining thermophilic for 4 h in advance and subsequently fermenting mesophilic for 34 h, the concentration of l-lactic acid with optical activity of 98.3% was improved to 16.6 ± 0.5 g COD/L at a high specific efficiency of 0.6097/d. PMID:26878176

  4. High titer L-lactic acid production from corn stover with minimum wastewater generation and techno-economic evaluation based on Aspen plus modeling.

    PubMed

    Liu, Gang; Sun, Jiaoe; Zhang, Jian; Tu, Yi; Bao, Jie

    2015-12-01

    Technological potentials of l-lactic acid production from corn stover feedstock were investigated by experimental and techno-economic studies. An optimal performance with 104.5 g/L in l-lactic acid titer and 71.5% in overall yield from cellulose in corn stover to l-lactic acid using an engineered Pediococcus acidilactici strain were obtained by overcoming several technical barriers. A rigorous Aspen plus model for l-lactic acid production starting from dry dilute acid pretreated and biodetoxified corn stover was developed. The techno-economic analysis shows that the minimum l-lactic acid selling price (MLSP) was $0.523 per kg, which was close to that of the commercial l-lactic acid produced from starch feedstock, and 24% less expensive than that of ethanol from corn stover, even though the xylose utilization was not considered. The study provided a prototype of industrial application and an evaluation model for high titer l-lactic acid production from lignocellulose feedstock. PMID:26454367

  5. L: (+)-Lactic acid production from non-food carbohydrates by thermotolerant Bacillus coagulans.

    PubMed

    Ou, Mark S; Ingram, Lonnie O; Shanmugam, K T

    2011-05-01

    Lactic acid is used as an additive in foods, pharmaceuticals, and cosmetics, and is also an industrial chemical. Optically pure lactic acid is increasingly used as a renewable bio-based product to replace petroleum-based plastics. However, current production of lactic acid depends on carbohydrate feedstocks that have alternate uses as foods. The use of non-food feedstocks by current commercial biocatalysts is limited by inefficient pathways for pentose utilization. B. coagulans strain 36D1 is a thermotolerant bacterium that can grow and efficiently ferment pentoses using the pentose-phosphate pathway and all other sugar constituents of lignocellulosic biomass at 50°C and pH 5.0, conditions that also favor simultaneous enzymatic saccharification and fermentation (SSF) of cellulose. Using this bacterial biocatalyst, high levels (150-180 g l(-1)) of lactic acid were produced from xylose and glucose with minimal by-products in mineral salts medium. In a fed-batch SSF of crystalline cellulose with fungal enzymes and B. coagulans, lactic acid titer was 80 g l(-1) and the yield was close to 80%. These results demonstrate that B. coagulans can effectively ferment non-food carbohydrates from lignocellulose to L: (+)-lactic acid at sufficient concentrations for commercial application. The high temperature fermentation of pentoses and hexoses to lactic acid by B. coagulans has these additional advantages: reduction in cellulase loading in SSF of cellulose with a decrease in enzyme cost in the process and a reduction in contamination of large-scale fermentations. PMID:20694852

  6. Enhancement of L-lactic acid production in Lactobacillus casei from Jerusalem artichoke tubers by kinetic optimization and citrate metabolism.

    PubMed

    Ge, Xiang-Yang; Qian, He; Zhang, Wei-Guo

    2010-01-01

    Efficient L-lactic acid production from Jerusalem artichoke tubers by Lactobacillus casei G-02 using simultaneous saccharification and fermentation (SSF) in fed-batch culture is demonstrated. The kinetic analysis in the SSF signified that the inulinase activity was subjected to product inhibition, while the fermentation activity of G-02 was subjected to substrate inhibition. It was also found that the intracellularly NOX activity was enhanced by the citrate metabolism, which increased the carbon flux of Embden-Meyerhof-Parnas (EMP) pathway dramatically, and resulted more ATP production. As a result, when the SSF was carried out at 40 degrees after the initial hydrolysis of 1 h with supplemented sodium citrate of 10g/L, L-lactic acid concentration of 141.5 g/L was obtained in 30 h with a volumetric productivity of 4.7 g/L/h. The conversion efficiency and product yield were 93.6% of the theoretical lactic acid yield and 52.4 g lactic acid/100 g Jerusalem artichoke flour, respectively. Such a high concentration of lactic acid with high productivity from Jerusalem artichoke has not been reported previously, and hence G-02 could be a potential candidate for economical production of L-lactic acid from Jerusalem artichoke at a commercial scale. PMID:20134240

  7. Improvement of L-lactic acid production by osmotic-tolerant mutant of Lactobacillus casei at high temperature.

    PubMed

    Ge, Xiang-Yang; Yuan, Jian; Qin, Hao; Zhang, Wei-Guo

    2011-01-01

    L-Lactic acid production by Lactobacillus casei was used as a model to study the mechanism of substrate inhibition and the strategy for enhancing L-lactic acid production. It was found that the concentration of cell growth and L-lactate decreased with the increase of glucose concentration and fermentation temperature. To enhance the osmotic stress resistance of the strain at high temperature, a mutant G-03 was screened and selected with 360 g/L glucose at 45°C as the selective criterion. To further increase the cell growth for lactic acid production, 3 g/L of biotin was supplemented to the medium. As a result, L: -lactate concentration by the mutant G-03 reached 198.2 g/L (productivity of 5.5 g L(-1) h(-1)) at 41°C in a 7-L fermentor with 210 g/L glucose as carbon source. L: -Lactate concentration and productivity of mutant G-03 were 115.2% and 97.8% higher than those of the parent strain, respectively. The strategy for enhancing L: -lactic acid production by increasing osmotic stress resistance at high temperature may provide an alternative approach to enhance organic acid production with other strains. PMID:20857288

  8. Improvement of L-lactic acid production from Jerusalem artichoke tubers by mixed culture of Aspergillus niger and Lactobacillus sp.

    PubMed

    Ge, Xiang-Yang; Qian, He; Zhang, Wei-Guo

    2009-03-01

    Aspergillus niger SL-09 and Lactobacillus sp. G-02 were used as a mixed culture in a 7-l fermentor to directly form L-lactic acid from Jerusalem artichoke tubers. The synthesis of inulinase and invertase from A. niger SL-09 was enhanced significantly by the inoculation of Lactobacillus sp. G-02 at 12h of culture, which reached 275.6 and 571.8 U/ml in 60 h, over 5-folds higher than that of the culture using single strain. In the following simultaneous saccharification and fermentation procedure, the highest L-lactic acid concentration of 120.5 g/l was obtained in 36 h of the fed-batch fermentation with high conversion efficiency of 94.5%. PMID:18990562

  9. Production of high concentration of L-lactic acid from cellobiose by thermophilic Bacillus coagulans WCP10-4.

    PubMed

    Ong, Shufen Angeline; Ng, Zhi Jian; Wu, Jin Chuan

    2016-07-01

    Thermophilic Bacillus coagulans WCP10-4 is found to be able to convert cellobiose to optically pure L-lactic acid. Its β-glucosidase activity is detected in whole cells (7.3 U/g dry cells) but not in culture medium, indicating the intracellular location of the enzyme. Its β-glucosidase activity is observed only when cultured using cellobiose as the sole carbon source, indicating that the expression of this enzyme is tightly regulated in cells. The enzyme is most active at 50 °C and pH 7.0. The supplement of external β-glucosidase during fermentation of cellobiose (106 g/l) by B. coagulans WCP10-4 increased the fermentation time from 21 to 23 h and decreased the lactic acid yield from 96.1 to 92.9 % compared to the control without β-glucosidase supplementation. B. coagulans WCP10-4 converted 200 g/l of cellobiose to 196.3 g/l of L-lactic acid at a yield of 97.8 % and a productivity of 7.01 g/l/h. This result shows that B. coagulans WCP10-4 is a highly efficient strain for converting cellobiose to L-lactic acid without the need of supplementing external β-glucosidases. PMID:27183994

  10. Antiviral Potential of Selected Starter Cultures, Bacteriocins and D,L-Lactic Acid.

    PubMed

    Lange-Starke, Anett; Petereit, A; Truyen, U; Braun, P G; Fehlhaber, K; Albert, T

    2014-03-01

    The antiviral potential of selected bacteria species [lactic acid bacteria (LAB) and micrococcaceae] was examined. By this, the effect of their cell-free supernatants as well as of certain species-related metabolites (sakacin A, nisin, and lactic acid) was investigated on different viruses after exposure at 24 °C for 3 days. Viruses were incubated with supernatants and metabolites in a dilution ratio of 1:10. Data for antiviral effects towards murine norovirus S99 (MNV), influenza A virus A/WSN/33 (H1N1), Newcastle disease virus Montana (NDV) and feline herpesvirus KS 285 (FHV) were generated in vitro simulating pH and temperature conditions according to raw sausage fermentations. Investigations showed no antiviral effect of sakacin A and nisin on MNV, H1N1, FHV and NDV. Furthermore, the antiviral potential of D,L-lactic acid was determined for MNV and H1N1. At raw sausage-related pH values (5.0-6.2) it could be shown that the virus titre for MNV and H1N1 was reduced by a maximum of 3.25 log and 2.5 log units, respectively. In addition, 29 culture supernatants of different bacteria species, mainly LAB and staphylococci, were tested for their antiviral activity against MNV. Only the cell-free supernatant of a Lb. curvatus strain showed a higher virus titre reduction of MNV by 1.25 log units compared to the control. Further studies on the characterisation of this cell-free supernatant were carried out, however, the antiviral substance could not be identified so far. PMID:24297091

  11. Non-Sterilized Fermentative Production of Polymer-Grade L-Lactic Acid by a Newly Isolated Thermophilic Strain Bacillus sp. 2–6

    PubMed Central

    Qin, Jiayang; Zhao, Bo; Wang, Xiuwen; Wang, Limin; Yu, Bo; Ma, Yanhe; Ma, Cuiqing; Tang, Hongzhi; Sun, Jibin; Xu, Ping

    2009-01-01

    Background The demand for lactic acid has been increasing considerably because of its use as a monomer for the synthesis of polylactic acid (PLA), which is a promising and environment-friendly alternative to plastics derived from petrochemicals. Optically pure l-lactic acid is essential for polymerization of PLA. The high fermentation cost of l-lactic acid is another limitation for PLA polymers to compete with conventional plastics. Methodology/Principal Findings A Bacillus sp. strain 2–6 for production of l-lactic acid was isolated at 55°C from soil samples. Its thermophilic characteristic made it a good lactic acid producer because optically pure l-lactic acid could be produced by this strain under open condition without sterilization. In 5-liter batch fermentation of Bacillus sp. 2–6, 118.0 g/liter of l-lactic acid with an optical purity of 99.4% was obtained from 121.3 g/liter of glucose. The yield was 97.3% and the average productivity was 4.37 g/liter/h. The maximum l-lactic acid concentration of 182.0 g/liter was obtained from 30-liter fed-batch fermentation with an average productivity of 3.03 g/liter/h and product optical purity of 99.4%. Conclusions/Significance With the newly isolated Bacillus sp. strain 2–6, high concentration of optically pure l-lactic acid could be produced efficiently in open fermentation without sterilization, which would lead to a new cost-effective method for polymer-grade l-lactic acid production from renewable resources. PMID:19194504

  12. Effect of L-lactic acid, short-chain fatty acids, and pH in cecal infusate on morphometric and cell kinetic parameters of rat cecum.

    PubMed

    Ichikawa, H; Sakata, T

    1997-08-01

    We studied the influences of cecal infusion of NaCl, short-chain fatty acids (SCFA), and L-lactic acid at pH 5.0 or 7.0 for seven days on morphometric and cell kinetic parameters of the rat cecum. SCFA increased relative weight of the mucosa and submucosa, crypt size, and mitotic index in the cecum. L-Lactic acid stimulated mitosis only at pH 5.0. Crypt size correlated positively to epithelial proliferative activity only when NaCl or L-lactic acid was infused. SCFA should have changed the balance between production and loss of the cecal epithelial cells. The infusate pH by itself had no effect, but modified the effects of SCFA and L-lactic acid in different ways. Crypt size correlated positively to the logarithm of daily proton load of infusates. The above results indicate that epithelial cell proliferation in the cecum is influenced by both SCFA and L-lactic acid, although differently, and by proton load. PMID:9286223

  13. Optimization of L(+)-Lactic Acid Production from Xylose with Rhizopus Oryzae Mutant RLC41-6 Breeding by Low-Energy Ion Implantation

    NASA Astrophysics Data System (ADS)

    Yang, Yingge; Fan, Yonghong; Li, Wen; Wang, Dongmei; Wu, Yuejin; Zheng, Zhiming; Yu, Zengliang

    2007-10-01

    In order to obtain an industrial strain with a higher L(+)-lactic acid yield, the strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion beam implantation and the mutant strain Rhizopus oryzae RLC41-6 was obtained. An experimental finding was made in surprise that Rhizopus oryzae mutant RLC41-6 is not only an L(+)-lactic acid producer from corn starch but also an efficient producer of L(+)-lactic acid from xylose. Under optimal conditions, the production of L(+)-lactic acid from 100 g/L xylose reached 77.39 g/L after 144 h fed-batch fermentation. A high mutation rate and a wide mutation spectrum of low-energy ion implantation were observed in the experiment.

  14. Simultaneous saccharification and fermentation (SSF) of jackfruit seed powder (JFSP) to l-lactic acid and to polylactide polymer.

    PubMed

    Nair, Nimisha Rajendran; Nampoothiri, K Madhavan; Banarjee, Rintu; Reddy, Gopal

    2016-08-01

    A newly isolated amylolytic lactic acid bacterium, Streptococcus equinus, was used for the production of l-lactic acid from jackfruit seed powder (JFSP) by simultaneous saccharification and fermentation (SSF). After optimization of shake flask fermentation by a response surface box-behnken design, the maximum lactate titer was 109g/L from 200g/L jackfruit seed powder. Amberlite IRA67, a weak base resin, was used to recover pure lactic acid from fermented broth and subsequently used for the synthesis of polylactic acid by direct condensation polymerization method with a yield of 62%. PMID:27005791

  15. Laboratory Studies of Aedes aegypti Attraction to Ketones, Sulfides, and Primary Chloroalkanes Tested Alone and in Combination with L-Lactic Acid.

    PubMed

    Bernier, Ulrich R; Kline, Daniel L; Allan, Sandra A; Barnard, Donald R

    2015-03-01

    The attraction of female Aedes aegypti to single compounds and binary compositions containing L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because of their structural relation to acetone, dimethyl disulfide, and dichloromethane, which have all been reported to synergize attraction to L-lactic acid. Human odors, carbon dioxide, and the binary mixture of L-lactic acid and CO₂served as controls for comparison of attraction responses produced by the binary mixtures. All tested mixtures that contained chloroalkanes attracted mosquitoes at synergistic levels, as did L-lactic acid and CO₂. Synergism was less frequent in mixtures of L-lactic acid with sulfides and ketones; in the case of ketones, synergistic attraction was observed only for L-lactic acid combined with acetone or butanone. Suppression or inhibition of attraction response was observed for combinations that contained ketones of C7-C12 molecular chain length (optimum in the C8-C10 range). This inhibition effect is similar to that observed previously for specific ranges of carboxylic acids, aldehydes, and alcohols. PMID:25843177

  16. Efficient production of l-lactic acid from hydrolysate of Jerusalem artichoke with immobilized cells of Lactococcus lactis in fibrous bed bioreactors.

    PubMed

    Shi, Zhouming; Wei, Peilian; Zhu, Xiangcheng; Cai, Jin; Huang, Lei; Xu, Zhinan

    2012-10-10

    Hydrolysate of Jerusalem artichoke was applied for the production of l-lactic acid by immobilized Lactococcus lactis cells in a fibrous bed bioreactor system. Preliminary experiments had indicated that the high quality hydrolysate, which was derived from the 40 min acid treatment at 95 °C and pH 1.8, was sufficient to support the cell growth and synthesis of l-lactic acid. With the addition of 5 g/l yeast extract, the fermentative performance of free cell system was evidently improved. After the basal settlement of hydrolysate based fermentation, the batch mode and the fed-batch mode fermentation were carried out in the free cell system and the fibrous bed bioreactor system, respectively. In all cases the immobilized cells presented the superior ability to produce l-lactic acid. The comparison of batch mode and fed-batch mode also indicated that the growth-limiting feeding strategy could reduce the lag phase of fermentation process and enhance the production of l-lactic acid. The achieved maximum concentration of l-lactic acid was 142 g/l in the fed-batch mode. Subsequent repeated-batch fermentation of the fibrous bed bioreactor system had further exhibited the persistence and stability of this system for the high production of l-lactic acid in a long term. Our work suggested the great potential of the fibrous bed bioreactor system and hydrolysate of J. artichoke in the economical production of l-lactic acid at industrial scale. PMID:22975123

  17. Enhanced L-lactic acid production in Lactobacillus paracasei by exogenous proline addition based on comparative metabolite profiling analysis.

    PubMed

    Tian, Xiwei; Wang, Yonghong; Chu, Ju; Zhuang, Yingping; Zhang, Siliang

    2016-03-01

    This study investigated cell physiological and metabolic responses of Lactobacillus paracasei to osmotic stresses. Both cellular fatty acid composition and metabolite profiling were responded by increasing unsaturated and epoxy-fatty acid proportions, as well as accumulating some specific intracellular metabolites. Simultaneously, metabolite profiling was adopted to rationally and systematically discover potential osmoprotectants. Consequently, exogenous addition of proline or aspartate was validated to be a feasible and efficacious approach to improve cell growth under hyperosmotic stress in shake flasks. Particularly, with 5-L cultivation system, L-lactic acid concentration increased from 108 to 150 g/L during the following 16-h fermentation in 2 g/L proline addition group, while it only increased from 110 to 140 g/L in no proline addition group. Moreover, glucose consumption rate with proline addition reached 3.49 g/L/h during this phase, 35.8 % higher than that with no proline addition. However, extreme high osmotic pressure would significantly limit the osmoprotection of proline, and the osmolality threshold for L. paracasei was approximately 3600 mOsm/kg. It was suggested that proline principally played a role as a compatible solute accumulated in the cell for hyperosmotic preservation. The strategies of exploiting osmotic protectant with metabolite profiling and enhancing L-lactic acid production by osmoprotectant addition would be potential to provide a new insight for other microorganisms and organic acids production. PMID:26658821

  18. Efficient production of polymer-grade L-lactic acid from corn stover hydrolyzate by thermophilic Bacillus sp. strain XZL4.

    PubMed

    Xue, Zhangwei; Wang, Limin; Ju, Jiansong; Yu, Bo; Xu, Ping; Ma, Yanhe

    2012-01-01

    Lactic acid has been identified as one of the top 30 potential building-block chemicals from biomass. Therefore, the search for cheap raw materials is an objective to reduce the production costs. Efficient polymer-grade L-lactic acid production was achieved in this report by a thermophilic strain Bacillus sp. XZL4 using corn stover hydrolyzate as sole carbon source. High L-lactic acid concentration (81.0 g L(-1)) was obtained from 162.5 g L(-1) concentrated corn stover hydrolyzate (total reducing sugar of 83.0 g L(-1)) with a volumetric productivity of 1.86 g L(-1) h(-1) (0-36 h) and a product yield of 0.98 g g(-1) total reducing sugars. This is the highest L-lactic acid concentration and yield reported from corn stover hydrolyzate. And the high optical purity of L-lactic acid obtained in this study also indicated that Bacillus sp. XZL4 is a promising polymer-grade L-lactic-acid producer from cellulosic biomass. PMID:23961368

  19. High-efficiency l-lactic acid production by Rhizopus oryzae using a novel modified one-step fermentation strategy.

    PubMed

    Fu, Yong-Qian; Yin, Long-Fei; Zhu, Hua-Yue; Jiang, Ru

    2016-10-01

    In this study, lactic acid fermentation by Rhizopus oryzae was investigated using the two different fermentation strategies of one-step fermentation (OSF) and conventional fermentation (CF). Compared to CF, OSF reduced the demurrage of the production process and increased the production of lactic acid. However, the qp was significantly lower than during CF. Based on analysis of μ, qs and qp, a novel modified OSF strategy was proposed. This strategy aimed to achieve a high final concentration of lactic acid, and a high qp by R. oryzae. In this strategy, the maximum lactic acid concentration and productivity of the lactic acid production stage reached 158g/l and 5.45g/(lh), which were 177% and 366% higher, respectively, than the best results from CF. Importantly, the qp and yield did not decrease. This strategy is a convenient and economical method for l-lactic acid fermentation by R. oryzae. PMID:27393831

  20. l-(+)-Lactic acid production by Lactobacillus rhamnosus B103 from dairy industry waste.

    PubMed

    Bernardo, Marcela Piassi; Coelho, Luciana Fontes; Sass, Daiane Cristina; Contiero, Jonas

    2016-01-01

    Lactic acid, which can be obtained through fermentation, is an interesting compound because it can be utilized in different fields, such as in the food, pharmaceutical and chemical industries as a bio-based molecule for bio-refinery. In addition, lactic acid has recently gained more interest due to the possibility of manufacturing poly(lactic acid), a green polymer that can replace petroleum-derived plastics and be applied in medicine for the regeneration of tissues and in sutures, repairs and implants. One of the great advantages of fermentation is the possibility of using agribusiness wastes to obtain optically pure lactic acid. The conventional batch process of fermentation has some disadvantages such as inhibition by the substrate or the final product. To avoid these problems, this study was focused on improving the production of lactic acid through different feeding strategies using whey, a residue of agribusiness. The downstream process is a significant bottleneck because cost-effective methods of producing high-purity lactic acid are lacking. Thus, the investigation of different methods for the purification of lactic acid was one of the aims of this work. The pH-stat strategy showed the maximum production of lactic acid of 143.7g/L. Following purification of the lactic acid sample, recovery of reducing sugars and protein and color removal were 0.28%, 100% and 100%, respectively. PMID:27266630

  1. Open fermentative production of L-lactic acid by Bacillus sp. strain NL01 using lignocellulosic hydrolyzates as low-cost raw material.

    PubMed

    Ouyang, Jia; Ma, Rui; Zheng, Zhaojuan; Cai, Cong; Zhang, Min; Jiang, Ting

    2013-05-01

    Highly efficient L-lactate production by a thermophilic strain Bacillus sp. NL01 was demonstrated in this study. Lignocellulosic hydrolyzates containing a high content of glucose, which was prepared from corn stover, was used as substrate for L-lactic acid production. The fermentation was carried out under open condition without sterilization and used NaOH as alkaline neutralizing reagent. In batch fermentation, 56.37 g l(-1) L-lactic acid was obtained from lignocellulosic hydrolyzates which contained the solid residues produced in enzymatic saccharification. In fed-batch fermentation, 75.03 g l(-1) L-lactic acid was obtained from lignocellulosic hydrolyzates supernatant. The yield was 74.5% and the average productivity was 1.04 g l(-1) h(-1). PMID:23127843

  2. The effect of pyruvate decarboxylase gene knockout in Saccharomyces cerevisiae on L-lactic acid production.

    PubMed

    Ishida, Nobuhiro; Saitoh, Satoshi; Onishi, Toru; Tokuhiro, Kenro; Nagamori, Eiji; Kitamoto, Katsuhiko; Takahashi, Haruo

    2006-05-01

    A plant- and crop-based renewable plastic, poly-lactic acid (PLA), is receiving attention as a new material for a sustainable society in place of petroleum-based plastics. We constructed a metabolically engineered Saccharomyces cerevisiae that has both pyruvate decarboxylase genes (PDC1 and PDC5) disrupted in the genetic background to express two copies of the bovine L-lactate dehydrogenase (LDH) gene. With this recombinant, the yield of lactate was 82.3 g/liter, up to 81.5% of the glucose being transformed into lactic acid on neutralizing cultivation, although pdc1 pdc5 double disruption led to ineffective decreases in cell growth and fermentation speed. This strain showed lactate productivity improvement as much as 1.5 times higher than the previous strain. This production yield is the highest value for a lactic acid-producing yeast yet reported. PMID:16717415

  3. Using tobacco waste extract in pre-culture medium to improve xylose utilization for l-lactic acid production from cellulosic waste by Rhizopus oryzae.

    PubMed

    Zheng, Yuxi; Wang, Yuanliang; Zhang, Jianrong; Pan, Jun

    2016-10-01

    The aim of this work was to study the high-titer l-lactic acid production from cellulosic waste using Rhizopus oryzae. The tobacco waste water-extract (TWE) added with 5g/L glucose and 0.1g/L vitamin C was optimized as pre-culture medium for R. oryzae. Results found that compared to traditional pre-culture medium, it improved xylose consumption rate up to 2.12-fold and enhanced l-lactic acid yield up to 1.73-fold. The highest l-lactic acid concentration achieved was 173.5g/L, corresponding to volumetric productivity of 1.45g/Lh and yield of 0.860g/g total reducing sugar in fed-batch fermentation. This process achieves efficient production of polymer-grade l-lactic acid from cellulosic feedstocks, lowers the cost of fungal cell pre-culture and provides a novel way for re-utilization of tobacco waste. PMID:27376833

  4. Laboratory studies of Aedes aegypti (L.) attraction to ketones, sulfides and primary chloroalkanes tested alone and in combination with l-lactic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The attraction of female Aedes aegypti to single compounds and binary compositions comprised of L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because o...

  5. Efficient hydrolysis of corncob residue through cellulolytic enzymes from Trichoderma strain G26 and L-lactic acid preparation with the hydrolysate.

    PubMed

    Xie, Lulu; Zhao, Jin; Wu, Jian; Gao, Mingfu; Zhao, Zhewei; Lei, Xiangyun; Zhao, Yi; Yang, Wei; Gao, Xiaoxue; Ma, Cuiyun; Liu, Huanfei; Wu, Fengjuan; Wang, Xingxing; Zhang, Fengwei; Guo, Pengyuan; Dai, Guifu

    2015-10-01

    To prepare fermentable hydrolysate from corncob residue (CCR), Trichoderma strain G26 was cultured on medium containing CCR for production of cellulolytic enzymes through solid-state fermentation (SSF), resulting in 71.3 IU/g (FPA), 136.2 IU/g (CMCase), 85.1 IU/g (β-glucosidase) and 11,344 IU/g (xylanase), respectively. Through a three-stage saccharification strategy, CCR was hydrolyzed by the enzymatic solution (6.5 FPU/ml) into fermentable hydrolysate containing 60.1g/l glucose (81.2% cellulose was converted at solid loading of 12.5%), 21.4% higher than that by the one-stage method. And then the hydrolysate was used to produce L-lactic acid by a previous screened strain Bacillus coagulans ZX25 in the submerged fermentation. 52.0 g/l L-lactic acid was obtained after fermentation for 44 h, with 86.5% glucose being converted to L-lactic acid. The results indicate that the strains and the hydrolysis strategy are promising for commercial production of L-lactic acid from CCR and other biomass. PMID:26143000

  6. Application of the biorefinery concept to produce L-lactic acid from the soybean vinasse at laboratory and pilot scale.

    PubMed

    Karp, Susan G; Igashiyama, Adriana H; Siqueira, Paula F; Carvalho, Júlio C; Vandenberghe, Luciana P S; Thomaz-Soccol, Vanete; Coral, Jefferson; Tholozan, Jean-Luc; Pandey, Ashok; Soccol, Carlos R

    2011-01-01

    Lactic acid is a product that finds several applications in food, cosmetic, pharmaceutical and chemical industries. The main objective of this work was the development of a bioprocess to produce L(+)-lactic acid using soybean vinasse as substrate. Among ten strains, Lactobacillus agilis LPB 56 was selected for fermentation, due to its ability to metabolize the complex oligosaccharides. Fermentation was conducted without need for supplementary inorganic nitrogen sources or yeast extract. Kinetic and yield parameters determined at laboratory scale were 0.864 and 0.0162 for YP/S and YX/S, 0.0145 g/L h (rx), 1.32 g/L h (rs) and 1.13 g/L h (rp). The use of vinasse enriched with soybean molasses provided higher lactic acid concentration (138 g/L), the best proportion of inoculum being 25% (v/v). After scale-up to a pilot plant, kinetic and yield parameters were 0.849 and 0.0353 for YP/S and YX/S, 0.0278 g/L h (rx), 0.915 g/L h (rs) and 0.863 g/L h (rp). PMID:20933391

  7. Influence of Vaginal Bacteria and d- and l-Lactic Acid Isomers on Vaginal Extracellular Matrix Metalloproteinase Inducer: Implications for Protection against Upper Genital Tract Infections

    PubMed Central

    Witkin, Steven S.; Mendes-Soares, Helena; Linhares, Iara M.; Jayaram, Aswathi; Ledger, William J.; Forney, Larry J.

    2013-01-01

    ABSTRACT We evaluated levels of vaginal extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase (MMP-8) in vaginal secretions in relation to the composition of vaginal bacterial communities and d- and l-lactic acid levels. The composition of vaginal bacterial communities in 46 women was determined by pyrosequencing the V1 to V3 region of 16S rRNA genes. Lactobacilli were dominant in 71.3% of the women, followed by Gardnerella (17.4%), Streptococcus (8.7%), and Enterococcus (2.2%). Of the lactobacillus-dominated communities, 51.5% were dominated by Lactobacillus crispatus, 36.4% by Lactobacillus iners, and 6.1% each by Lactobacillus gasseri and Lactobacillus jensenii. Concentrations of l-lactic acid were slightly higher in lactobacillus-dominated vaginal samples, but most differences were not statistically significant. d-Lactic acid levels were higher in samples containing L. crispatus than in those with L. iners (P < 0.0001) or Gardnerella (P = 0.0002). The relative proportion of d-lactic acid in vaginal communities dominated by species of lactobacilli was in concordance with the proportions found in axenic cultures of the various species grown in vitro. Levels of l-lactic acid (P < 0.0001) and the ratio of l-lactic acid to d-lactic acid (P = 0.0060), but not concentrations of d-lactic acid, were also correlated with EMMPRIN concentrations. Moreover, vaginal concentrations of EMMPRIN and MMP-8 levels were highly correlated (P < 0.0001). Taken together, the data suggest the relative proportion of l- to d-lactic acid isomers in the vagina may influence the extent of local EMMPRIN production and subsequent induction of MMP-8. The expression of these proteins may help determine the ability of bacteria to transverse the cervix and initiate upper genital tract infections. PMID:23919998

  8. Complete Genome Sequence of Enterococcus mundtii QU 25, an Efficient l-(+)-Lactic Acid-Producing Bacterium

    PubMed Central

    Shiwa, Yuh; Yanase, Hiroaki; Hirose, Yuu; Satomi, Shohei; Araya-Kojima, Tomoko; Watanabe, Satoru; Zendo, Takeshi; Chibazakura, Taku; Shimizu-Kadota, Mariko; Yoshikawa, Hirofumi; Sonomoto, Kenji

    2014-01-01

    Enterococcus mundtii QU 25, a non-dairy bacterial strain of ovine faecal origin, can ferment both cellobiose and xylose to produce l-lactic acid. The use of this strain is highly desirable for economical l-lactate production from renewable biomass substrates. Genome sequence determination is necessary for the genetic improvement of this strain. We report the complete genome sequence of strain QU 25, primarily determined using Pacific Biosciences sequencing technology. The E. mundtii QU 25 genome comprises a 3 022 186-bp single circular chromosome (GC content, 38.6%) and five circular plasmids: pQY182, pQY082, pQY039, pQY024, and pQY003. In all, 2900 protein-coding sequences, 63 tRNA genes, and 6 rRNA operons were predicted in the QU 25 chromosome. Plasmid pQY024 harbours genes for mundticin production. We found that strain QU 25 produces a bacteriocin, suggesting that mundticin-encoded genes on plasmid pQY024 were functional. For lactic acid fermentation, two gene clusters were identified—one involved in the initial metabolism of xylose and uptake of pentose and the second containing genes for the pentose phosphate pathway and uptake of related sugars. This is the first complete genome sequence of an E. mundtii strain. The data provide insights into lactate production in this bacterium and its evolution among enterococci. PMID:24568933

  9. New application of Bacillus strains for optically pure L-lactic acid production: general overview and future prospects.

    PubMed

    Poudel, Pramod; Tashiro, Yukihiro; Sakai, Kenji

    2016-01-01

    Members of the genus Bacillus are considered to be both, among the best studied and most commonly used bacteria as well as the most still unexplored and the most wide-applicable potent bacteria because novel Bacillus strains are continuously being isolated and used in various areas. Production of optically pure l-lactic acid (l-LA), a feedstock for bioplastic synthesis, from renewable resources has recently attracted attention as a valuable application of Bacillus strains. l-LA fermentation by other producers, including lactic acid bacteria and Rhizopus strains (fungi) has already been addressed in several reviews. However, despite the advantages of l-LA fermentation by Bacillus strains, including its high growth rate, utilization of various carbon sources, tolerance to high temperature, and growth in simple nutritional conditions, it has not been reviewed. This review article discusses new findings on LA-producing Bacillus strains and compares them to other producers. The future prospects for LA-producing Bacillus strains are also discussed. PMID:26565947

  10. Valorisation of mixed bakery waste in non-sterilized fermentation for L-lactic acid production by an evolved Thermoanaerobacterium sp. strain.

    PubMed

    Yang, Xiaofeng; Zhu, Muzi; Huang, Xiongliang; Lin, Carol Sze Ki; Wang, Jufang; Li, Shuang

    2015-12-01

    In this study, an advanced biorefinery technology that uses mixed bakery waste has been developed to produce l-lactic acid using an adaptively evolved Thermoanaerobacterium aotearoense LA1002-G40 in a non-sterilized system. Under these conditions, mixed bakery waste was directly hydrolysed by Aspergillus awamori and Aspergillus oryzae, resulting in a nutrient-rich hydrolysate containing 83.6g/L glucose, 9.5 g/L fructose and 612 mg/L free amino nitrogen. T. aotearoense LA1002-G40 was evaluated and then adaptively evolved to grow in this nutrient-rich hydrolysate. Using a 5-L fermenter, the overall lactic acid production from mixed bakery waste was 0.18 g/g with a titer, productivity and yield of 78.5 g/L, 1.63 g/L/h and 0.85 g/g, respectively. This is an innovative procedure involving a complete bioconversion process for l-lactic acid produced from mixed bakery waste under non-sterilized conditions. The proposed process could be potentially applied to turn food waste into l-lactic acid in an economically feasible way. PMID:26363501

  11. Betaine and Beet Molasses Enhance L-Lactic Acid Production by Bacillus coagulans

    PubMed Central

    Xu, Ke; Xu, Ping

    2014-01-01

    Lactic acid is an important chemical with various industrial applications, and it can be efficiently produced by fermentation, in which Bacillus coagulans strains present excellent performance. Betaine can promote lactic acid fermentation as an effective osmoprotectant. Here, positive effect of betaine on fermentation by B. coagulans is revealed. Betaine could enhance lactic acid production by protecting l-LDH activity and cell growth from osmotic inhibition, especially under high glucose concentrations and with poor organic nitrogen nutrients. The fermentation with 0.05 g/L betaine could produce 17.9% more lactic acid compared to the fermentation without betaine. Beet molasses, which is rich in sucrose and betaine, was utilized in a co-feeding fermentation and raised the productivity by 22%. The efficient lactic acid fermentation by B. coagulans is thus developed by using betaine and beet molasses. PMID:24956474

  12. Impacts of lignocellulose-derived inhibitors on L-lactic acid fermentation by Rhizopus oryzae.

    PubMed

    Zhang, Li; Li, Xin; Yong, Qiang; Yang, Shang-Tian; Ouyang, Jia; Yu, Shiyuan

    2016-03-01

    Inhibitors generated in the pretreatment and hydrolysis of corn stover and corn cob were identified. In general, they inhibited cell growth, lactate dehydrogenase, and lactic acid production but with less or no adverse effect on alcohol dehydrogenase and ethanol production in batch fermentation by Rhizopus oryzae. Furfural and 5-hydroxymethyl furfural (HMF) were highly toxic at 0.5-1 g L(-1), while formic and acetic acids at less than 4 g L(-1) and levulinic acid at 10 g L(-1) were not toxic. Among the phenolic compounds at 1 g L(-1), trans-cinnamic acid and syringaldehyde had the highest toxicity while syringic, ferulic and p-coumaric acids were not toxic. Although these inhibitors were present at concentrations much lower than their separately identified toxic levels, lactic acid fermentation with the hydrolysates showed much inferior performance compared to the control without inhibitor, suggesting synergistic or compounded effects of the lignocellulose-degraded compounds on inhibiting lactic acid fermentation. PMID:26724548

  13. L-lactic acid production from cellobiose and xylose by engineered 1 Saccharomyces cerevisiae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efficient and rapid production of value-added chemicals from lignocellulosic biomass is an important step towards a sustainable society. Lactic acid, used for synthesizing the bioplastic polylactide, has been produced by microbial fermentation using primarily glucose. Lignocellulosic hydrolysates co...

  14. Effect of fermentation conditions on L-lactic acid production from soybean straw hydrolysate.

    PubMed

    Wang, Juan; Wang, Qunhui; Xu, Zhong; Zhang, Wenyu; Xiang, Juan

    2015-01-01

    Four types of straw, namely, soybean, wheat, corn, and rice, were investigated for use in lactic acid production. These straws were mainly composed of cellulose, hemicellulose, and lignin. After pretreatment with ammonia, the cellulose content increased, whereas the hemicellulose and lignin contents decreased. Analytical results also showed that the liquid enzymatic hydrolysates were primarily composed of glucose, xylose, and cellobiose. Preliminary experiments showed that a higher lactic acid concentration could be obtained from the wheat and soybean straw. However, soybean straw was chosen as the substrate for lactic acid production owing to its high protein content. The maximum lactic acid yield (0.8 g/g) and lactic acid productivity (0.61 g/(l/h)) were obtained with an initial reducing sugar concentration of 35 g/l at 30°C when using Lactobacillus casei (10% inoculum) for a 42 h fermentation period. Thus, the experimental results demonstrated the feasibility of using a soybean straw enzymatic hydrolysate as a substrate for lactic acid production. PMID:25152056

  15. Simultaneous production of l-lactic acid with high optical activity and a soil amendment with food waste that demonstrates plant growth promoting activity.

    PubMed

    Kitpreechavanich, Vichien; Hayami, Arisa; Talek, Anfal; Chin, Clament Fui Seung; Tashiro, Yukihiro; Sakai, Kenji

    2016-07-01

    A unique method to produce highly optically-active l-lactic acid and soil amendments that promote plant growth from food waste was proposed. Three Bacillus strains Bacillus subtilis KBKU21, B. subtilis N3-9 and Bacillus coagulans T27, were used. Strain KBKU21 accumulated 36.9 g/L l-lactic acid with 95.7% optical activity and 98.2% l-lactic acid selectivity when fermented at 43°C for 84 h in a model kitchen refuse (MKR) medium. Residual precipitate fraction (anaerobically-fermented MKR (AFM) compost) analysis revealed 4.60%, 0.70% and 0.75% of nitrogen (as N), phosphorous (as P2O5), and potassium (as K2O), respectively. Additionally, the carbon to nitrogen ratio decreased from 13.3 to 10.6. AFM compost with KBKU21 promoted plant growth parameters, including leaf length, plant height and fresh weight of Brassica rapa (Komatsuna), than that by chemical fertilizers or commercial compost. The concept provides an incentive for the complete recycling of food waste, contributing towards a sustainable production system. PMID:26819060

  16. Methods and materials for the production of L-lactic acid in yeast

    SciTech Connect

    Hause, Ben; Rajgarhia, Vineet; Suominen, Pirkko

    2009-05-19

    Recombinant yeast are provided having, in one aspect, multiple exogenous LDH genes integrated into the genome, while leaving native PDC genes intact. In a second aspect, recombinant yeast are provided having an exogenous LDH gene integrated into its genome at the locus of a native PDC gene, with deletion of the native PDC gene. The recombinant yeast are useful in fermentation process for producing lactic acid.

  17. Expression of Lactate Dehydrogenase in Aspergillus niger for L-Lactic Acid Production

    PubMed Central

    Dave, Khyati K.; Punekar, Narayan S.

    2015-01-01

    Different engineered organisms have been used to produce L-lactate. Poor yields of lactate at low pH and expensive downstream processing remain as bottlenecks. Aspergillus niger is a prolific citrate producer and a remarkably acid tolerant fungus. Neither a functional lactate dehydrogenase (LDH) from nor lactate production by A. niger is reported. Its genome was also investigated for the presence of a functional ldh. The endogenous A. niger citrate synthase promoter relevant to A. niger acidogenic metabolism was employed to drive constitutive expression of mouse lactate dehydrogenase (mldhA). An appraisal of different branches of the A. niger pyruvate node guided the choice of mldhA for heterologous expression. A high copy number transformant C12 strain, displaying highest LDH specific activity, was analyzed under different growth conditions. The C12 strain produced 7.7 g/l of extracellular L-lactate from 60 g/l of glucose, in non-neutralizing minimal media. Significantly, lactate and citrate accumulated under two different growth conditions. Already an established acidogenic platform, A. niger now promises to be a valuable host for lactate production. PMID:26683313

  18. Wastes from bioethanol and beer productions as substrates for l(+) lactic acid production - A comparative study.

    PubMed

    Djukić-Vuković, Aleksandra; Mladenović, Dragana; Radosavljević, Miloš; Kocić-Tanackov, Sunčica; Pejin, Jelena; Mojović, Ljiljana

    2016-02-01

    Waste substrates from bioethanol and beer productions are cheap, abundant and renewable substrates for biorefinery production of lactic acid (LA) and variability in their chemical composition presents a challenge in their valorisation. Three types of waste substrates, wasted bread and wasted potato stillage from bioethanol production and brewers' spent grain hydrolysate from beer production were studied as substrates for the production of l(+) LA and probiotic biomass by Lactobacillus rhamnosus ATCC 7469. The correlation of the content of free alpha amino nitrogen and the production of LA was determined as a critical characteristic of the waste media for efficient LA production by L. rhamnosus on the substrates which contained equal amount of fermentable sugars. A maximal LA productivity of 1.54gL(-1)h(-1) was obtained on wasted bread stillage media, whilst maximal productivities achieved on the potato stillage and brewers' spent grain hydrolysate media were 1.28gL(-1)h(-1)and 0.48gL(-1)h(-1), respectively. A highest LA yield of 0.91gg(-1) was achieved on wasted bread stillage media, followed by the yield of 0.81gg(-1) on wasted potato stillage and 0.34gg(-1) on brewers' spent grain hydrolysate media. The kinetics of sugar consumption in the two stillage substrates were similar while the sugar conversion in brewers' spent grain hydrolysate was slower and less efficient due to significantly lower content of free alpha amino nitrogen. The lignocellulosic hydrolysate from beer production required additional supplementation with nitrogen. PMID:26639411

  19. Major Role of NAD-Dependent Lactate Dehydrogenases in the Production of l-Lactic Acid with High Optical Purity by the Thermophile Bacillus coagulans.

    PubMed

    Wang, Limin; Cai, Yumeng; Zhu, Lingfeng; Guo, Honglian; Yu, Bo

    2014-12-01

    Bacillus coagulans 2-6 is an excellent producer of optically pure l-lactic acid. However, little is known about the mechanism of synthesis of the highly optically pure l-lactic acid produced by this strain. Three enzymes responsible for lactic acid production-NAD-dependent l-lactate dehydrogenase (l-nLDH; encoded by ldhL), NAD-dependent d-lactate dehydrogenase (d-nLDH; encoded by ldhD), and glycolate oxidase (GOX)-were systematically investigated in order to study the relationship between these enzymes and the optical purity of lactic acid. Lactobacillus delbrueckii subsp. bulgaricus DSM 20081 (a d-lactic acid producer) and Lactobacillus plantarum subsp. plantarum DSM 20174 (a dl-lactic acid producer) were also examined in this study as comparative strains, in addition to B. coagulans. The specific activities of key enzymes for lactic acid production in the three strains were characterized in vivo and in vitro, and the levels of transcription of the ldhL, ldhD, and GOX genes during fermentation were also analyzed. The catalytic activities of l-nLDH and d-nLDH were different in l-, d-, and dl-lactic acid producers. Only l-nLDH activity was detected in B. coagulans 2-6 under native conditions, and the level of transcription of ldhL in B. coagulans 2-6 was much higher than that of ldhD or the GOX gene at all growth phases. However, for the two Lactobacillus strains used in this study, ldhD transcription levels were higher than those of ldhL. The high catalytic efficiency of l-nLDH toward pyruvate and the high transcription ratios of ldhL to ldhD and ldhL to the GOX gene provide the key explanations for the high optical purity of l-lactic acid produced by B. coagulans 2-6. PMID:25217009

  20. Major Role of NAD-Dependent Lactate Dehydrogenases in the Production of l-Lactic Acid with High Optical Purity by the Thermophile Bacillus coagulans

    PubMed Central

    Wang, Limin; Cai, Yumeng; Zhu, Lingfeng; Guo, Honglian

    2014-01-01

    Bacillus coagulans 2-6 is an excellent producer of optically pure l-lactic acid. However, little is known about the mechanism of synthesis of the highly optically pure l-lactic acid produced by this strain. Three enzymes responsible for lactic acid production—NAD-dependent l-lactate dehydrogenase (l-nLDH; encoded by ldhL), NAD-dependent d-lactate dehydrogenase (d-nLDH; encoded by ldhD), and glycolate oxidase (GOX)—were systematically investigated in order to study the relationship between these enzymes and the optical purity of lactic acid. Lactobacillus delbrueckii subsp. bulgaricus DSM 20081 (a d-lactic acid producer) and Lactobacillus plantarum subsp. plantarum DSM 20174 (a dl-lactic acid producer) were also examined in this study as comparative strains, in addition to B. coagulans. The specific activities of key enzymes for lactic acid production in the three strains were characterized in vivo and in vitro, and the levels of transcription of the ldhL, ldhD, and GOX genes during fermentation were also analyzed. The catalytic activities of l-nLDH and d-nLDH were different in l-, d-, and dl-lactic acid producers. Only l-nLDH activity was detected in B. coagulans 2-6 under native conditions, and the level of transcription of ldhL in B. coagulans 2-6 was much higher than that of ldhD or the GOX gene at all growth phases. However, for the two Lactobacillus strains used in this study, ldhD transcription levels were higher than those of ldhL. The high catalytic efficiency of l-nLDH toward pyruvate and the high transcription ratios of ldhL to ldhD and ldhL to the GOX gene provide the key explanations for the high optical purity of l-lactic acid produced by B. coagulans 2-6. PMID:25217009

  1. Freeze-drying of polycaprolactone and poly(D,L-lactic-glycolic) nanoparticles induce minor particle size changes affecting the oral pharmacokinetics of loaded drugs.

    PubMed

    Saez, A; Guzmán, M; Molpeceres, J; Aberturas, M R

    2000-11-01

    The present study was geared at identifying the conditions to stabilize poly (D,L-lactic-glycolic) (PLGA) and polycaprolactone (PCL) nanoparticles (NP) by freeze-drying with several cryoprotective agents. Differential scanning calorimetry and freeze-thawing studies were used to optimize the lyophilization process. These studies showed that all samples were totally frozen at -45 degrees C and evidenced the necessity of adding sucrose, glucose, trehalose or gelatine to preserve the properties of NP regardless of the freezing procedure. However, only 20% sucrose and 20% glucose exerted an acceptable lyoprotective effect on PLGA and PCL NP, respectively. Nonetheless, the final to initial size ratios ( approximately 1.5) indicated that particle size was slightly affected in both cases. In vivo studies with CyA-loaded PCL NP whose sizes matched those obtained after NP preparation (100 nm) and after being lyophilized (160 nm) showed that the changes of particle size might have some relevance on drug pharmacokinetics. The MRT was significantly (P<0.05) modified after an oral CyA dose of 5 mg/kg and the treatment with 160-nm sized CyA-loaded NP produced a higher drug partition into the liver of Wistar rats potentially affecting the toxic and immunosuppressive profile of the drug. Therefore, although the particle size changes induced by NP lyophilization were slight, they need to be carefully evaluated and cannot be neglected. PMID:11072195

  2. Chitin and L(+)-lactic acid production from crab (Callinectes bellicosus) wastes by fermentation of Lactobacillus sp. B2 using sugar cane molasses as carbon source.

    PubMed

    Flores-Albino, Belem; Arias, Ladislao; Gómez, Jorge; Castillo, Alberto; Gimeno, Miquel; Shirai, Keiko

    2012-09-01

    Crab wastes are employed for simultaneous production of chitin and L(+)-lactic acid by submerged fermentation of Lactobacillus sp. B2 using sugar cane molasses as carbon source. Response surface methodology was applied to design the culture media considering demineralization. Fermentations in stirred tank reactor (2L) using selected conditions produced 88% demineralization and 56% deproteinization with 34% yield of chitin and 19.5 gL(-1) of lactic acid (77% yield). The chitin purified from fermentation displayed 95% degree of acetylation and 0.81 and 1 ± 0.125% of residual ash and protein contents, respectively. PMID:22367529

  3. L-Lactic acid production by combined utilization of agricultural bioresources as renewable and economical substrates through batch and repeated-batch fermentation of Enterococcus faecalis RKY1.

    PubMed

    Reddy, Lebaka Veeranjaneya; Kim, Young-Min; Yun, Jong-Sun; Ryu, Hwa-Won; Wee, Young-Jung

    2016-06-01

    Enterococcus faecalis RKY1 was used to produce l-lactic acid from hydrol, soybean curd residues (SCR), and malt. Hydrol was efficiently metabolized to l-lactic acid with optical purity of >97.5%, though hydrol contained mixed sugars such as glucose, maltose, maltotriose, and maltodextrin. Combined utilization of hydrol, SCR, and malt was enough to sustain lactic acid fermentation by E. faecalis RKY1. In order to reduce the amount of nitrogen sources and product inhibition, cell-recycle repeated-batch fermentation was employed, where a high cell mass (26.3g/L) was obtained. Lactic acid productivity was improved by removal of lactic acid from fermentation broth by membrane filtration and by linearly increased cell density. When the total of 10 repeated-batch fermentations were carried out using 100g/L hydrol, 150g/L SCR hydrolyzate, and 20g/L malt hydrolyzate as the main nutrients, lactic acid productivity was increased significantly from 3.20g/L/h to 6.37g/L/h. PMID:26970921

  4. Fermentative utilization of coffee mucilage using Bacillus coagulans and investigation of down-stream processing of fermentation broth for optically pure l(+)-lactic acid production.

    PubMed

    Neu, Anna-Katrin; Pleissner, Daniel; Mehlmann, Kerstin; Schneider, Roland; Puerta-Quintero, Gloria Inés; Venus, Joachim

    2016-07-01

    In this study, mucilage, a residue from coffee production, was investigated as substrate in fermentative l(+)-lactic acid production. Mucilage was provided as liquid suspension consisting glucose, galactose, fructose, xylose and sucrose as free sugars (up to 60gL(-1)), and used directly as medium in Bacillus coagulans batch fermentations carried out at 2 and 50L scales. Using mucilage and 5gL(-1) yeast extract as additional nitrogen source, more than 40gL(-1) lactic acid was obtained. Productivity and yield were 4-5gL(-1)h(-1) and 0.70-0.77g lactic acid per g of free sugars, respectively, irrespective the scale. Similar yield was found when no yeast extract was supplied, the productivity, however, was 1.5gL(-1)h(-1). Down-stream processing of culture broth, including filtration, electrodialysis, ion exchange chromatography and distillation, resulted in a pure lactic acid formulation containing 930gL(-1)l(+)-lactic acid. Optical purity was 99.8%. PMID:27035470

  5. The optimization of l-lactic acid production from sweet sorghum juice by mixed fermentation of Bacillus coagulans and Lactobacillus rhamnosus under unsterile conditions.

    PubMed

    Wang, Yong; Chen, Changjing; Cai, Di; Wang, Zheng; Qin, Peiyong; Tan, Tianwei

    2016-10-01

    The cost reduction of raw material and sterilization could increase the economic feasibility of l-lactic acid fermentation, and the development of an cost-effective and efficient process is highly desired. To improve the efficiency of open fermentation by Lactobacillus rhamnosus based on sweet sorghum juice (SSJ) and to overcome sucrose utilization deficiency of Bacillus coagulans, a mixed fermentation was developed. Besides, the optimization of pH, sugar concentration and fermentation medium were also studied. Under the condition of mixed fermentation and controlled pH, a higher yield of 96.3% was achieved, compared to that (68.8%) in sole Lactobacillus rhamnosus fermentation. With an optimized sugar concentration and a stepwise-controlled pH, the l-lactic acid titer, yield and productivity reached 121gL(-1), 94.6% and 2.18gL(-1)h(-1), respectively. Furthermore, corn steep powder (CSP) as a cheap source of nitrogen and salts was proved to be an efficient supplement to SSJ in this process. PMID:27469090

  6. Development of Conducting Polyaniline/ Poly(Lactic Acid) Nanofibers by Electrospinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultrafine fibers consisting of blends of polyaniline doped with p-toluene sulfonic acid and poly(L-lactic acid) were prepared by electrospinning. The presence of polyaniline resulted in fibers with diameters as thin as 100– 200 nm and a significant reduction of bead formation. These fibers were visu...

  7. Injectable Poly-L-Lactic Acid: Understanding Its Use in the Current Era.

    PubMed

    Lorenc, Z Paul; Greene, Thomas; Gottschalk, Ronald W

    2016-06-01

    A survey of Sculptra® Aesthetic injectors was conducted to understand how the product is being currently reconstituted and injected. Questions were asked of injectors to understand their reasons for choice and volume of diluent(s), additions, and time for the reconstitution process. These results are discussed in the context of the past history of the product over the last decade, with a focus on adverse events such as papules and nodules.

    J Drugs Dermatol. 2016;15(6):759-762. PMID:27272085

  8. Characterization of an air-spun poly(L-lactic acid) nanofiber mesh.

    PubMed

    François, Sébastien; Sarra-Bournet, Christian; Jaffre, Antoine; Chakfé, Nabil; Durand, Bernard; Laroche, Gaétan

    2010-05-01

    It was previously showed that PLLA nanofiber mesh promoted good endothelial cell proliferation. A new technique was developed to produce nanofibers by air jet spinning inside the tubular shape of vascular prostheses and to characterize this nanofiber mesh. Polymer macromolecule stability was assessed by gel permeation chromatography. Thermal analyses were conducted with differential scanning calorimetry and dynamic mechanical analysis on PLLA nanofibers obtained with 4% and 7% solutions (w/v) in chloroform. Polyethylene terephthalate (PET) was also treated with atmospheric pressure dielectric barrier discharge under air or nitrogen atmosphere to optimize PLLA nanofiber adherence, assessed by peel tests. Air spinning induced a reduction of number-average molecular weight (M(n)) for the 7% PLLA solution but not for the 4% solution. The nanofibers were more crystalline and less sensible to viscoelastic relaxation as a function of aging in the 4% solution than in the 7% solution. Discharge treatment of the PET promoted identical surface modification on PET film and PET textile surfaces. Moreover, the best PLLA nanofibers adhesion results were obtained under nitrogen atmosphere. This study demonstrates that it is possible to coat the internal side of tubular vascular prostheses with PLLA nanofibers, and provides a better understanding of the air spinning process as well as optimizing nanofibers adhesion. PMID:20186825

  9. Enhanced in Vitro Mineralization and in Vivo Osteogenesis of Composite Scaffolds through Controlled Surface Grafting of L-Lactic Acid Oligomer on Nanohydroxyapatite.

    PubMed

    Wang, Zongliang; Xu, Yang; Wang, Yu; Ito, Yoshihiro; Zhang, Peibiao; Chen, Xuesi

    2016-03-14

    Nanocomposite of hydroxyapatite (HA) surface grafted with L-lactic acid oligomer (LAc oligomer) (op-HA) showed improved interface compatibility, mechanical property, and biocompatibility in our previous study. In this paper, composite scaffolds of op-HA with controlled grafting different amounts of LAc oligomer (1.1, 5.2, and 9.1 wt %) were fabricated and implanted to repair rabbit radius defects. The dispersion of op-HA nanoparticles was more uniform than n-HA in chloroform and nanocomposites scaffold. Calcium and phosphorus exposure, in vitro biomineralization ability, and cell proliferation were much higher in the op-HA1.1 wt %/PLGA scaffolds than the other groups. The osteodifferentiation and bone fusion in animal tests were significantly enhanced for op-HA5.2 wt %/PLGA scaffolds. The results indicated that the grafted LAc oligomer of 5.2 or 9.1 wt %, which formed a barrier layer on the HA surface, prevented the exposure of nucleation sites. The shielded nucleation sites of op-HA particles (5.2 wt %) might be easily exposed as the grafted LAc oligomer was decomposed easily by enzyme systems in vivo. Findings from this study have revealed that grafting 1.1 wt % amount of LAc oligomer on hydroxyapatite could improve in vitro mineralization, and 5.2 wt % could promote in vivo osteogenesis capacity of composite scaffolds. PMID:26821731

  10. Novel pH control strategy for efficient production of optically active l-lactic acid from kitchen refuse using a mixed culture system.

    PubMed

    Tashiro, Yukihiro; Inokuchi, Shota; Poudel, Pramod; Okugawa, Yuki; Miyamoto, Hirokuni; Miayamoto, Hisashi; Sakai, Kenji

    2016-09-01

    Uninvestigated control factors of meta-fermentation, the fermentative production of pure chemicals and fuels in a mixed culture system, were examined for production of optically pure l-lactic acid (LA) from food waste. In meta-fermentations by pH swing control, l-LA production with 100% optical purity (OPl-LA) was achieved even using unsterilized model kitchen refuse medium with preferential proliferation of l-LA-producing Bacillus coagulans, a minor member in the seed, whereas agitation decreased OPl-LA drastically. pH constant control shortened the fermentation time but decreased OPl-LA and LA selectivity (SLA) by stimulating growth of heterofermentative Bacillus thermoamylovorans. Deliberately switching from pH swing control to constant control exhibited the best performance for l-LA production: maximum accumulation, 39.2gL(-1); OPl-LA, 100%; SLA, 96.6%; productivity, 1.09gL(-1)h(-1). These results present a novel pH control strategy for efficient l-LA production in meta-fermentation based on a concept different from that of pure culture systems. PMID:27233097

  11. Fermentative l-lactic acid production from pretreated whole slurry of oil palm trunk treated by hydrothermolysis and subsequent enzymatic hydrolysis.

    PubMed

    Eom, In-Yong; Oh, Young-Hoon; Park, Si Jae; Lee, Seung-Hwan; Yu, Ju-Hyun

    2015-06-01

    A simple and cost-effective biochemical conversion process consisting of hydrothermal treatment, enzymatic hydrolysis and fermentation of pretreated whole slurry (PWS) was developed for producing l-lactic acid (L-LA) from oil palm trunk (OPT). When OPT was hydrothermally treated at optimal condition capable of achieving maximum yield of hemicellulosic sugars after enzymatic hydrolysis, the enzymatic digestibility of the PWS afforded a yield of 81.4% of the theoretical glucose yield (TGY). However, glucose yield from washed pretreated solid (WPS) was only 43.5% of TGY. The use of two hydrolysates from PWS and WPS for fermentation by Lactobacillus paracasei engineered to selectively produce L-LA afforded yields of 89.5% and 45.8% of the theoretical LA yield (TLY), respectively. This study confirmed the inevitable extensive sugar loss during washing of pretreated slurry due to loss of soluble starch. Alternatively, the proposed design process is considered suitable for converting OPT to L-LA without such starch loss. PMID:25768416

  12. Preparation of antimicrobial membranes: coextrusion of poly(lactic acid) and Nisaplin in the presence of plasticizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nisin is a naturally occurring antimicrobial polypeptide, and is popularly used in foods and food packaging industries. Nisin is deactivated at temperatures higher than 120 deg C, and therefore can not be directly incorporated into poly(L-lactic acid) (PLA), a biomass-derived biodegradable polymer, ...

  13. Optimization of L-(+)-lactic acid production by ring and disc plastic composite supports through repeated-batch biofilm fermentation.

    PubMed Central

    Ho, K L; Pometto, A L; Hinz, P N

    1997-01-01

    Four customized bioreactors, three with plastic composite supports (PCS) and one with suspended cells (control), were operated as repeated-batch fermentors for 66 days at pH 5 and 37 degrees C. The working volume of each customized reactor was 600 ml, and each reactor's medium was changed every 2 to 5 days for 17 batches. The performance of PCS bioreactors in long-term biofilm repeated-batch fermentation was compared with that of suspended-cell bioreactors in this research. PCS could stimulate biofilm formation, supply nutrients to attached and free suspended cells, and reduce medium channelling for lactic acid production. Compared with conventional repeated-batch fermentation, PCS bioreactors shortened the lag time by threefold (control, 11 h; PCS, 3.5 h) and sixfold (control, 9 h; PCS, 1.5 h) at yeast extract concentrations of 0.4 and 0.8% (wt/vol), respectively. They also increased the lactic acid productivity of Lactobacillus casei subsp. rhamnosus (ATCC 11443) by 40 to 70% and shortened the total fermentation time by 28 to 61% at all yeast extract concentrations. The fastest productivity of the PCS bioreactors (4.26 g/liter/h) was at a starting glucose concentration of 10% (wt/vol), whereas that of the control (2.78 g/liter/h) was at 8% (wt/vol). PCS biofilm lactic acid fermentation can drastically improve the fermentation rate with reduced complex-nutrient addition. PMID:9212403

  14. L+-lactic acid production from starch by a novel amylolytic Lactococcus lactis subsp. lactis B84.

    PubMed

    Petrov, Kaloyan; Urshev, Zoltan; Petrova, Penka

    2008-06-01

    A new Lactococcus lactis subsp. lactis B84, capable of utilizing starch as a sole carbon source and producing L(+)-lactate, was isolated from spontaneously fermented rye sourdough. Aiming at maximum lactic acid productivity, the components of the media and the cultivation conditions were varied. In MRS-starch medium (with absence of yeast and meat extracts), at 33 degrees C, agitation 200 rpm and pH 6.0 for 6 days complete starch hydrolysis occurred and 5.5 gl(-1) lactic acid were produced from 18 gl(-1) starch. The identification of strain B84 was based on genetic criteria. Amplified ribosomal DNA restriction analysis (ARDRA), PCR with species-specific primers and sequencing of the 16S rDNA proved its species affiliation. Four genes for enzymes, involved in starch degradation were detected in B84 genome: amyL, amyY, glgP and apu, coding cytoplasmic and extracellular alpha-amylases, glycogen phosphorylase and amylopullulanase, respectively. Reverse transcription PCR experiments showed that both genes, encoding alpha-amylases (amyL and amyY) were expressed into mRNAs, whereas apu and glgP were not. Amylase activity assay was performed at different pH and temperatures. The cell-bond amylase proved to be the key enzyme, involved in the starch hydrolysis with maximum activity at 45 degrees C and pH 5.4. PMID:18456109

  15. Self-assembling biomaterials: Liquid crystal phases of cholesteryl oligo(l-lactic acid) and their interactions with cells

    PubMed Central

    Hwang, Julia J.; Iyer, Subramani N.; Li, Li-Sheng; Claussen, Randal; Harrington, Daniel A.; Stupp, Samuel I.

    2002-01-01

    We report here on the synthesis and characterization of a series of self-assembling biomaterials with molecular features designed to interact with cells and scaffolds for tissue regeneration. The molecules of these materials contain cholesteryl moieties, which have universal affinity for cell membranes, and short chains of lactic acid, a common component of biodegradable tissue engineering matrices. The materials were synthesized in good yields with low polydispersities in the range of 1.05–1.15, and their characterization was carried out by small-angle x-ray diffraction, transmission electron microscopy, electron diffraction, differential scanning calorimetry, and atomic force microscopy. These molecular materials form layered structures that can be described as smectic phases and can also order into single-crystal stacks with an orthorhombic unit cell. Their layer spacings range from 58 to 99 Å, corresponding to bilayers of oligomers with an average of 10 and 37 lactic acid residues, respectively. The self-organized layered structures were found to promote improved fibroblast adhesion and spreading, although the specific mechanism for this observed response remains unknown. The ability of self-assembling materials to present ordered and periodic bulk structures to cells could be a useful strategy in tissue engineering. PMID:12119419

  16. Direct conversion of chicory flour into L(+)-lactic acid by the highly effective inulinase producer Lactobacillus paracasei DSM 23505.

    PubMed

    Petrova, Penka; Velikova, Petya; Popova, Luiza; Petrov, Kaloyan

    2015-06-01

    Highly effective bio-process for lactic acid (LA) production by simultaneous saccharification and fermentation (SSF) of chicory flour was developed. The strain used, Lactobacillus paracasei DSM 23505 produced natural inulinase (EC 3.2.1.80) with molecular weight ∼130 kDa, located in the cell wall fraction. In batch fermentation with optimized medium content and fermentation conditions, a complete conversion of 136 g/L chicory flour (89.3% inulin and 10.7% mix of sucrose, fructose and glucose) into 123.7 g/L LA was achieved. These yield and conversion rate are the highest obtained by SSF for LA production from inulin. The high efficiency, the cheap fermentation broth and the simple process performance disclose the promising use of the chicory flour in industrial biotechnology for LA production. PMID:25824595

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  18. Engineering of near infrared fluorescent proteinoid-poly(L-lactic acid) particles for in vivo colon cancer detection

    PubMed Central

    2014-01-01

    Background The use of near-infrared (NIR) fluorescence imaging techniques has gained great interest for early detection of cancer owing to the negligible absorption and autofluorescence of water and other intrinsic biomolecules in this region. The main aim of the present study is to synthesize and characterize novel NIR fluorescent nanoparticles based on proteinoid and PLLA for early detection of colon tumors. Methods The present study describes the synthesis of new proteinoid-PLLA copolymer and the preparation of NIR fluorescent nanoparticles for use in diagnostic detection of colon cancer. These fluorescent nanoparticles were prepared by a self-assembly process in the presence of the NIR dye indocyanine green (ICG), a FDA-approved NIR fluorescent dye. Anti-carcinoembryonic antigen antibody (anti-CEA), a specific tumor targeting ligand, was covalently conjugated to the P(EF-PLLA) nanoparticles through the surface carboxylate groups using the carbodiimide activation method. Results and discussion The P(EF-PLLA) nanoparticles are stable in different conditions, no leakage of the encapsulated dye into PBS containing 4% HSA was detected. The encapsulation of the NIR fluorescent dye within the P(EF-PLLA) nanoparticles improves significantly the photostability of the dye. The fluorescent nanoparticles are non-toxic, and the biodistribution study in a mouse model showed they evacuate from the body over 24 h. Specific colon tumor detection in a chicken embryo model and a mouse model was demonstrated for anti-CEA-conjugated NIR fluorescent P(EF-PLLA) nanoparticles. Conclusions The results of this study suggest a significant advantage of NIR fluorescence imaging using NIR fluorescent P(EF-PLLA) nanoparticles over colonoscopy. In future work we plan to broaden this study by encapsulating cancer drugs such as paclitaxel and/or doxorubicin, within these biodegradable NIR fluorescent P(EF-PLLA) nanoparticles, for both detection and therapy of colon cancer. PMID:25113279

  19. Composite Membranes of Recombinant Silkworm Antimicrobial Peptide and Poly (L-lactic Acid) (PLLA) for biomedical application

    PubMed Central

    Li, Zhi; Liu, Xuan; Li, Yi; Lan, Xiqian; Leung, Polly Hangmei; Li, Jiashen; Li, Gang; Xie, Maobin; Han, Yanxia; Lin, Xiaofen

    2016-01-01

    Antimicrobial peptides, produced by innate immune system of hosts in response to invading pathogens, are capable of fighting against a spectrum of bacteria, viruses, fungi, parasites and cancer cells. Here, a recombinant silkworm AMP Bmattacin2 from heterologous expression is studied, indicating a broad spectrum of antibacterial activity and showing selective killing ability towards skin and colon cancer cells over their normal cell counterparts. For the purpose of biomedical application, the electrospinning fabrication technique is employed to load Bmattacin2 into PLLA nanofibrous membrane. In addition to a good compatibility with the normal cells, Bmattacin2 loaded nanofibrous membranes demonstrate instant antibacterial effects and sustained anticancer effects. The cancer cell and bacteria targeting dynamics of recombinant Bmattacin2 are investigated. With these characteristics, PLLA/Bmattacin2 composite membranes have a great potential for developing novel biomedical applications such as cancer therapies and wound healing treatments. PMID:27503270

  20. Toward accelerated bone regeneration by altering poly(D,L-lactic-co-glycolic) acid porogen content in calcium phosphate cement.

    PubMed

    van Houdt, C I A; Preethanath, R S; van Oirschot, B A J A; Zwarts, P H W; Ulrich, D J O; Anil, S; Jansen, J A; van den Beucken, J J J P

    2016-02-01

    This work aimed to compare in vitro degradation of dense PLGA microspheres and milled PLGA particles as porogens within CPC, considering that the manufacturing of milled PLGA is more cost-effective when compared with PLGA microspheres. Additionally, we aimed to examine the effect of porogen amount within CPC/PLGA on degradation and bone formation. Our in vitro results showed no differences between both forms of PLGA particles (as porogens in CPC; spherical for microspheres, irregular for milled) regarding morphology, porosity, and degradation. Using milled PLGA as porogens within CPC/PLGA, we evaluated the effect of porogen amount on degradation and bone forming capacity in vivo. Titanium landmarks surrounded by CPC/PLGA with 30 and 50 wt % PLGA, were implanted in forty femoral bone defects of twenty male Wistar rats. Histomorphometrical results showed a significant temporal decrease in the amount of CPC, for both formulas, and confirmed that 50 wt % PLGA degrades faster than 30 wt%, and allows for a 1.5-fold higher amount of newly formed bone. Taken together, this study demonstrated that (i) milled PLGA particles perform equal to PLGA microspheres, and (ii) tuning of the PLGA content in CPC/PLGA is a feasible approach to leverage material degradation and bone formation. PMID:26454146

  1. Composite Membranes of Recombinant Silkworm Antimicrobial Peptide and Poly (L-lactic Acid) (PLLA) for biomedical application.

    PubMed

    Li, Zhi; Liu, Xuan; Li, Yi; Lan, Xiqian; Leung, Polly Hangmei; Li, Jiashen; Li, Gang; Xie, Maobin; Han, Yanxia; Lin, Xiaofen

    2016-01-01

    Antimicrobial peptides, produced by innate immune system of hosts in response to invading pathogens, are capable of fighting against a spectrum of bacteria, viruses, fungi, parasites and cancer cells. Here, a recombinant silkworm AMP Bmattacin2 from heterologous expression is studied, indicating a broad spectrum of antibacterial activity and showing selective killing ability towards skin and colon cancer cells over their normal cell counterparts. For the purpose of biomedical application, the electrospinning fabrication technique is employed to load Bmattacin2 into PLLA nanofibrous membrane. In addition to a good compatibility with the normal cells, Bmattacin2 loaded nanofibrous membranes demonstrate instant antibacterial effects and sustained anticancer effects. The cancer cell and bacteria targeting dynamics of recombinant Bmattacin2 are investigated. With these characteristics, PLLA/Bmattacin2 composite membranes have a great potential for developing novel biomedical applications such as cancer therapies and wound healing treatments. PMID:27503270

  2. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-05-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids` being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  3. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-01-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids' being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  4. Melting of α'- and α-crystals of poly(lactic acid)

    NASA Astrophysics Data System (ADS)

    Di Lorenzo, Maria Laura; Androsch, René

    2016-05-01

    The influence of chain structure on thermal stability of α'-crystals of poly(lactic acid) (PLA) with high L-lactic acid content (96-100 %) is detailed in this contribution. α'-crystals of PLA grow at temperatures below 120 °C, and spontaneously transform into stable α-modification during heating. Using conventional differential scanning calorimetry (DSC) and fast scanning chip calorimetry (FSC), a wide range of scanning rates, between about 10-1 and 102 K s-1 could be tested. It was found that reorganization of disordered α'-crystals into stable α-crystals can be suppressed by fast heating. The critical heating rate needed to completely melt α'-crystals and to avoid formation of α-crystals on continuation of heating varies with the chain composition, and decreases upon increase of the D-lactic acid content in the PLA chain.

  5. Poly lactic acid based foams prepared via thermally induced phase separation (TIPS): A method to tune the crystallinity

    NASA Astrophysics Data System (ADS)

    Pavia, Francesco Carfı; La Carrubba, Vincenzo; Brucato, Valerio

    2012-07-01

    Blends of Poly-L-Lactic Acid (PLLA) with two Poly-Lactic Acid (PLA) in different proportions (90/10 and 70/30) were utilized in order to produce biodegradable and biocompatible scaffolds for soft tissue engineering applications. The scaffolds were produced via thermally induced phase separation (TIPS) starting from ternary systems where dioxane was the solvent and water the non-solvent. Morphology was evaluated by Scanning Electron Microscopy (average pore size and interconnection). Moreover a DSC analysis was carried out on the as-obtained scaffold in order to obtain information about theirs thermal properties (enthalpy of melt and crystallization). The results showed that is possible to prepare scaffolds of PLLA/PLA via TIPS. Moreover, the PLA seems to influences the TIPS process in terms of demixing temperatures. The data confirm that the morphology and the mechanical properties of the scaffold can be tuned, starting from PLLA blends and using PLA with different molecular weights.

  6. Fundamentals of poly(lactic acid) microstructure, crystallization behavior, and properties

    NASA Astrophysics Data System (ADS)

    Kang, Shuhui

    Poly(lactic acid) is an environmentally-benign biodegradable and sustainable thermoplastic material, which has found broad applications as food packaging films and as non-woven fibers. The crystallization and deformation mechanisms of the polymer are largely determined by the distribution of conformation and configuration. Knowledge of these mechanisms is needed to understand the mechanical and thermal properties on which processing conditions mainly depend. In conjunction with laser light scattering, Raman spectroscopy and normal coordinate analysis are used in this thesis to elucidate these properties. Vibrational spectroscopic theory, Flory's rotational isomeric state (RIS) theory, Gaussian chain statistics and statistical mechanics are used to relate experimental data to molecular chain structure. A refined RIS model is proposed, chain rigidity recalculated and chain statistics discussed. A Raman spectroscopic characterization method for crystalline and amorphous phase orientation has been developed. A shrinkage model is also proposed to interpret the dimensional stability for fibers and uni- or biaxially stretched films. A study of stereocomplexation formed by poly(l-lactic acid) and poly(d-lactic acid) is also presented.

  7. Poly(hydroxy acids) in drug delivery.

    PubMed

    Juni, K; Nakano, M

    1987-01-01

    Poly(hydroxy acids) so far have been examined for use in drug delivery in limited number, while the advantageous use of the polymers has been recognized due to their biodegradability and biocompatibility. Homo- and copolymers of lactic acid and glycolic acid have been studied in drug delivery by many workers, while homo- and copolymers of epsilon-caprolactone have been studied by only one group of workers. Although poly-hydroxybutyric acid had been found to be a naturally occurring polymer, examination as to the use of the polymer in drug delivery is rather recent and reports are still limited. In the present article, the use of poly(hydroxy acids) including homo- and copolymers of lactic acid and glycolic acid, polycaprolactone, and poly-beta-hydroxybutyric acid in drug delivery is reviewed. Physicochemical properties, biodegradability, and biocompatibility of the polymers, and evaluations in vitro and in vivo of specific dosage forms using the polymers, are included. The most recent work in our laboratories on the use of polyactic acid and poly-beta-hydroxybutyric acid is also included. PMID:3549007

  8. Thermoresponsive physical hydrogels of poly(lactic acid)/poly(ethylene glycol) stereoblock copolymers tuned by stereostructure and hydrophobic block sequence.

    PubMed

    Mao, Hailiang; Shan, Guorong; Bao, Yongzhong; Wu, Zi Liang; Pan, Pengju

    2016-05-18

    CBABC-type poly(lactic acid) (PLA)/poly(ethylene glycol) (PEG) pentablock copolymers composed of a central PEG block (A) and enantiomeric poly(l-lactic acid) (PLLA, B), poly(d-lactic acid) (PDLA, C) blocks were synthesized. Such pentablock copolymers form physical hydrogels at high concentrations in an aqueous solution, which stem from the aggregation and physical bridging of copolymer micelles. These gels are thermoresponsive and turn into sols upon heating. Physical gelation, gel-to-sol transition, crystalline state, microstructure, rheological behavior, biodegradation, and drug release behavior of PLA/PEG pentablock copolymers and their gels were investigated; they were also compared with PLA-PEG-PLA triblock copolymers containing the isotactic PLLA or atactic poly(d,l-lactide) (PDLLA) endblocks and PLLA-PEG-PLLA/PDLA-PEG-PDLA enantiomeric mixtures. PLA hydrophobic domains in pentablock copolymer gels changed from a homocrystalline to stereocomplexed structure as the PLLA/PDLA block length ratio approached 1/1. The gel of symmetric pentablock copolymer exhibited a wider gelation region, higher gel-to-sol transition temperature, higher hydrophobic domain crystallinity, larger intermicellar distance, higher storage modulus, and slower degradation and drug release rate compared to those of the asymmetric PLA/PEG pentablock copolymers or triblock copolymers. SAXS results indicated that the PLLA/PDLA blocks stereocomplexation in pentablock copolymers facilitated the intermicellar aggregation and bridging. Cylindrical ordered structures were observed in all the gels formed from the PLA/PEG pentablock and triblock copolymers. The stereocomplexation degree and intermicellar distance of the pentablock copolymer gels increased with heating. PMID:27121732

  9. Quantitative analysis of mechanical and electrostatic properties of poly(lactic) acid fibers and poly(lactic) acid-carbon nanotube composites using atomic force microscopy.

    PubMed

    Iqbal, Qais; Bernstein, Peter; Zhu, Yazhe; Rahamim, Joseph; Cebe, Peggy; Staii, Cristian

    2015-03-13

    We use atomic force microscopy (AFM) to perform a systematic quantitative characterization of the elastic modulus and dielectric constant of poly(L-lactic acid) electrospun nanofibers (PLLA), as well as composites of PLLA fibers with 1.0 wt% embedded multiwall carbon nanotubes (MWCNTs-PLLA). The elastic moduli are measured in the fiber skin region via AFM nanoindentation, and the dielectric constants are determined by measuring the phase shifts obtained via electrostatic force microscopy (EFM). We find that the average value for the elastic modulus for PLLA fibers is (9.8 ± 0.9) GPa, which is a factor of 2 larger than the measured average elastic modulus for MWCNT-PLLA composites (4.1 ± 0.7) GPa. We also use EFM to measure dielectric constants for both types of fibers. These measurements show that the dielectric constants of the MWCNT-PLLA fibers are significantly larger than the corresponding values obtained for PLLA fiber. This result is consistent with the higher polarizability of the MWCNT-PLLA composites. The measurement methods presented are general, and can be applied to determine the mechanical and electrical properties of other polymers and polymer nanocomposites. PMID:25683087

  10. Synthesis and self-assembly of poly(3-hexylthiophene)-block-poly(acrylic acid)

    SciTech Connect

    Li, Zicheng; Ono, Robert J.; Wu, Zong-Quan; Bielawski, Christopher W.

    2011-01-01

    A modular and convenient synthesis of ethynyl end functionalized poly(3-hexylthiophene) in high purity is reported; this material facilitated access to poly(3-hexylthiophene)-block-poly(acrylic acid) which self-assembled into hierarchical structures.

  11. Tailoring the morphology and crystallinity of poly(L-lactide acid) electrospun membranes

    NASA Astrophysics Data System (ADS)

    Ribeiro, Clarisse; Sencadas, Vitor; Costa, Carlos Miguel; Luís Gómez Ribelles, José; Lanceros-Méndez, Senentxu

    2011-02-01

    Biodegradable poly(L-lactic acid) (PLLA) microfibers were prepared by electrospinning by varying the applied potential, solution flow rate and collector conditions. PLLA fibers with smoothly oriented and random morphologies were obtained and characterized by scanning electron microscopy. The optimum fiber orientation was obtained at 1000 rpm using a 20.3 cm diameter collecting drum, while for higher and lower drum rotation speeds, the rapid random motion of the jets resulted in a random fiber distribution. The deformation of the jet with rapid solidification during electrospinning often results in a metastable phase. PLLA electrospun fibers are amorphous but contain numerous crystal nuclei that rapidly grow when the sample is heated to 70-140 °C. In this way, the degree of crystallinity of the fibers can be tailored between 0 and 50% by annealing. Infrared transmission spectra revealed that the processing conditions do not affect the PLLA samples at the molecular level and that the crystallinity of the samples is related to the presence of α-crystals.

  12. Exclusive Stereocomplex Crystallization of Linear and Multiarm Star-Shaped High-Molecular-Weight Stereo Diblock Poly(lactic acid)s.

    PubMed

    Han, Lili; Shan, Guorong; Bao, Yongzhong; Pan, Pengju

    2015-11-01

    Linear, 3-arm, and 6-arm star-shaped stereo diblock copolymers of l- and d-lactic acid (PLLA-b-PDLA) with high molecular weights (MWs) were synthesized via two-step ring-opening polymerization (ROP) with 1-dodechanol, glycerol, and d-sorbitol as the initiators, respectively. The chemical structure, nonisothermal and isothermal crystallization kinetics, crystalline structure, lamellar morphology, and mechanical thermal properties of PLLA-b-PDLAs with different macromolecular topologies were investigated. Compared to the high-molecular-weight (MW) poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic blends, PLLA-b-PDLAs exhibit faster crystallization upon cooling and isothermal melt crystallization; they crystallize exclusively in stereocomplex (sc) crystallites under all of the conditions investigated. This is attributable to the enhanced interactions between enantiomeric blocks linked covalently. Macromolecular topology influences the crystallization kinetics and crystalline structure of PLLA-b-PDLAs significantly. The crystallization temperature upon cooling, melting temperature, degree of crystallinity, spherulitic growth rate, crystallite size, long period, and crystalline layer thickness of PLLA-b-PDLA decrease with increasing branching number because of the retarding effect of branching on the crystallization rate and crystallizability. Because of the formation of high-melting-point sc crystallites, both the linear and star-shaped PLLA-b-PDLAs exhibit better thermal resistance and higher storage moduli at high temperature than does homocrystalline PLLA. PMID:26457767

  13. Quantitative analysis of mechanical and electrostatic properties of poly(lactic) acid fibers and poly(lactic) acid—carbon nanotube composites using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Iqbal, Qais; Bernstein, Peter; Zhu, Yazhe; Rahamim, Joseph; Cebe, Peggy; Staii, Cristian

    2015-03-01

    We use atomic force microscopy (AFM) to perform a systematic quantitative characterization of the elastic modulus and dielectric constant of poly(L-lactic acid) electrospun nanofibers (PLLA), as well as composites of PLLA fibers with 1.0 wt% embedded multiwall carbon nanotubes (MWCNTs-PLLA). The elastic moduli are measured in the fiber skin region via AFM nanoindentation, and the dielectric constants are determined by measuring the phase shifts obtained via electrostatic force microscopy (EFM). We find that the average value for the elastic modulus for PLLA fibers is (9.8 ± 0.9) GPa, which is a factor of 2 larger than the measured average elastic modulus for MWCNT-PLLA composites (4.1 ± 0.7) GPa. We also use EFM to measure dielectric constants for both types of fibers. These measurements show that the dielectric constants of the MWCNT-PLLA fibers are significantly larger than the corresponding values obtained for PLLA fiber. This result is consistent with the higher polarizability of the MWCNT-PLLA composites. The measurement methods presented are general, and can be applied to determine the mechanical and electrical properties of other polymers and polymer nanocomposites.

  14. Cotton wool-like poly(lactic acid)/vaterite composite scaffolds releasing soluble silica for bone tissue engineering.

    PubMed

    Obata, Akiko; Ozasa, Hiroki; Kasuga, Toshihiro; Jones, Julian R

    2013-07-01

    Cotton wool-like poly(L-lactic acid) and siloxane-doped vaterite (SiV) composite scaffolds were prepared with a modified electrospinning system for bone tissue engineering applications. The effects of changing the SiV content in the materials from 10 to 30 wt% on elasticity and the ability to release calcium ions and soluble silica were evaluated. The elasticity of the cotton wool-like composites was almost the same as that of the PLLA from the results of compressibility and recovery tests. The materials released calcium ions for more than 56 days and soluble silica for 28-56 days in a tris buffer solution (pH 7.4). Mouse osteoblast-like cells (MC3T3-E1 cells) were cultured on/in the cotton wool-like materials or the fibremats out of the same composite materials as that used for the cotton wool-like materials. The cells penetrated into and proliferated inside the cotton wool-like materials, although they mainly adhered on the fibremat surface. PMID:23606191

  15. Zwitterionic Poly(amino acid methacrylate) Brushes

    PubMed Central

    2014-01-01

    A new cysteine-based methacrylic monomer (CysMA) was conveniently synthesized via selective thia-Michael addition of a commercially available methacrylate-acrylate precursor in aqueous solution without recourse to protecting group chemistry. Poly(cysteine methacrylate) (PCysMA) brushes were grown from the surface of silicon wafers by atom-transfer radical polymerization. Brush thicknesses of ca. 27 nm were achieved within 270 min at 20 °C. Each CysMA residue comprises a primary amine and a carboxylic acid. Surface zeta potential and atomic force microscopy (AFM) studies of the pH-responsive PCysMA brushes confirm that they are highly extended either below pH 2 or above pH 9.5, since they possess either cationic or anionic character, respectively. At intermediate pH, PCysMA brushes are zwitterionic. At physiological pH, they exhibit excellent resistance to biofouling and negligible cytotoxicity. PCysMA brushes undergo photodegradation: AFM topographical imaging indicates significant mass loss from the brush layer, while XPS studies confirm that exposure to UV radiation produces surface aldehyde sites that can be subsequently derivatized with amines. UV exposure using a photomask yielded sharp, well-defined micropatterned PCysMA brushes functionalized with aldehyde groups that enable conjugation to green fluorescent protein (GFP). Nanopatterned PCysMA brushes were obtained using interference lithography, and confocal microscopy again confirmed the selective conjugation of GFP. Finally, PCysMA undergoes complex base-catalyzed degradation in alkaline solution, leading to the elimination of several small molecules. However, good long-term chemical stability was observed when PCysMA brushes were immersed in aqueous solution at physiological pH. PMID:24884533

  16. Zwitterionic poly(amino acid methacrylate) brushes.

    PubMed

    Alswieleh, Abdullah M; Cheng, Nan; Canton, Irene; Ustbas, Burcin; Xue, Xuan; Ladmiral, Vincent; Xia, Sijing; Ducker, Robert E; El Zubir, Osama; Cartron, Michael L; Hunter, C Neil; Leggett, Graham J; Armes, Steven P

    2014-07-01

    A new cysteine-based methacrylic monomer (CysMA) was conveniently synthesized via selective thia-Michael addition of a commercially available methacrylate-acrylate precursor in aqueous solution without recourse to protecting group chemistry. Poly(cysteine methacrylate) (PCysMA) brushes were grown from the surface of silicon wafers by atom-transfer radical polymerization. Brush thicknesses of ca. 27 nm were achieved within 270 min at 20 °C. Each CysMA residue comprises a primary amine and a carboxylic acid. Surface zeta potential and atomic force microscopy (AFM) studies of the pH-responsive PCysMA brushes confirm that they are highly extended either below pH 2 or above pH 9.5, since they possess either cationic or anionic character, respectively. At intermediate pH, PCysMA brushes are zwitterionic. At physiological pH, they exhibit excellent resistance to biofouling and negligible cytotoxicity. PCysMA brushes undergo photodegradation: AFM topographical imaging indicates significant mass loss from the brush layer, while XPS studies confirm that exposure to UV radiation produces surface aldehyde sites that can be subsequently derivatized with amines. UV exposure using a photomask yielded sharp, well-defined micropatterned PCysMA brushes functionalized with aldehyde groups that enable conjugation to green fluorescent protein (GFP). Nanopatterned PCysMA brushes were obtained using interference lithography, and confocal microscopy again confirmed the selective conjugation of GFP. Finally, PCysMA undergoes complex base-catalyzed degradation in alkaline solution, leading to the elimination of several small molecules. However, good long-term chemical stability was observed when PCysMA brushes were immersed in aqueous solution at physiological pH. PMID:24884533

  17. Preparation of poly (styrene)-b-poly (acrylic acid)/γ-Fe 2O 3 composites

    NASA Astrophysics Data System (ADS)

    Zhang, L. D.; Liu, W. L.; Xiao, C. L.; Yao, J. S.; Fan, Z. P.; Sun, X. L.; Zhang, X.; Wang, L.; Wang, X. Q.

    2011-12-01

    The use of a block copolymer, poly (styrene)-b-poly (acrylic acid) (PS-b-PAA) to prepare a magnetic nanocomposite was investigated. Poly (styrene)-poly (t-butyl acrylate) block copolymer, being synthesized by atom transfer radical polymerization, was hydrolyzed with hydrochloric acid for obtaining PS-b-PAA. The obtained PS-b-PAA was then compounded with the modified γ-Fe2O3, and subsequently the magnetic nanocomposite was achieved. The products were characterized by 1H NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, transmission electron microscopy and vibrating sample magnetometer. The results showed that the nanocomposites exhibited soft magnetism, with the mean diameter of 100 nm approximately.

  18. New nucleic acid triple helix, Poly(AAU)

    SciTech Connect

    Broitman, S.L.; Im, D.D.; Fresco, J.R.

    1987-05-01

    A polynucleotide helical structure containing two strands of poly(A) and one of poly(U) has been discovered. The stoichiometry of the complex was determined by continuous variation titrations and isosbestic wavelength analysis. Thermal denaturation profiles were used to examine complex stability over a wide range of conditions. The complex forms only when the poly(A) strands are of molecular weight between 9000-50,000 Daltons (dp approx. 28-150), whereas the size of the poly(U) strand has no effect. This limitation may explain why poly(AAU) was not observed in previous investigations. The complex shows inverse dependence of stability on ionic strength, but is not favored by decreasing pH. This behavior, together with the intermediate poly(A) size requirement suggest that the conformational entropy of the poly(A) strands is a critical determinant of the stability of this complex. The potential of the poly(A) tails of mRNA for formation of this triple helix, and of AAU/T triplet formation to contribute to the binding of unique sequence RNA strands to gene-encoding nucleic acid double helices are noted.

  19. pH-Sensitive Micelles Based on Double-Hydrophilic Poly(methylacrylic acid)-Poly(ethylene glycol)-Poly(methylacrylic acid) Triblock Copolymer

    NASA Astrophysics Data System (ADS)

    Tao, Youhua; Liu, Ren; Liu, Xiaoya; Chen, Mingqing; Yang, Cheng; Ni, Zhongbin

    2009-04-01

    pH-sensitive micelles with hydrophilic core and hydrophilic corona were fabricated by self-assembling of triblock copolymer of poly(methylacrylic acid)-poly(ethylene glycol)-poly(methylacrylic acid) at lower solution pH. Transmission electron microscopy and laser light scattering studies showed micelles were in nano-scale with narrow size distribution. Solution pH value and the micelles concentration strongly influenced the hydrodynamic radius of the spherical micelles (48-310 nm). A possible mechanism for the formation of micelles was proposed. The obtained polymeric micelle should be useful for biomedical materials such as carrier of hydrophilic drug.

  20. In vitro degradation and in vivo biocompatibility of poly(lactic acid) mesh for soft tissue reinforcement in vaginal surgery.

    PubMed

    de Tayrac, Renaud; Chentouf, Samir; Garreau, Henri; Braud, Christian; Guiraud, Isabelle; Boudeville, Philippe; Vert, Michel

    2008-05-01

    This study was aimed at evaluating the in vitro degradation, the in vivo biocompatibility and at comparing the effects of two methods of sterilization on poly(L-lactic acid) (PLA(94)) resorbable mesh. The mesh was manufactured to be used as surgical soft tissue reinforcement in the vaginal area. Samples of 100 mg of PLA(94) mesh (10 x 10 mm(2)) were immersed in isoosmolar 0.13M, pH 7.4 phosphate buffer solution at 37 degrees C, during 12 months. The hydrolytic degradation up to 12 months after immersion was monitored by measuring weight loss, mesh area changes, and by various analytical techniques namely Differential scanning calorimetry (DSC), capillary zone electrophoresis (CZE), size exclusion chromatography (SEC), and environmental scanning electron microscopy (ESEM). Specimens of nonsterilized, ethylene-oxide (ETO) sterilized, and gamma-ray sterilized PLA(94) mesh were compared. Fifteen samples were implanted in an incisional hernia Wistar rat model. Histopathology was performed up to 90 days after implantation to evaluate the inflammatory response and the collagen deposition. Although the decrease of molecular weight due to polymer chain scissions started 6 weeks after in vitro immersion, water-soluble degradation products and decrease of tensile strength appeared after 8 months only. Analyses showed also that ETO sterilization did not affect the degradation of the PLA(94) mesh. In contrast, gamma-ray sterilization increased very much the sensitivity of the mesh to the hydrolytic degradation. In vivo, the PLA(94) mesh exhibited good biocompatibility over the investigated time period. PMID:18161812

  1. Protective Effects of Indole-3-Carbinol-Loaded Poly(lactic-co-glycolic acid) Nanoparticles Against Glutamate-Induced Neurotoxicity.

    PubMed

    Jeong, Ji Heun; Kim, Jwa-Jin; Bak, Dong Ho; Yu, Kwang Sik; Lee, Je Hun; Lee, Nam Seob; Jeong, Young Gil; Kim, Do Kyung; Kim, Dong-Kwan; Han, Seung-Yun

    2015-10-01

    Indole-3-carbinol (I3C) has anti-oxidant and anti-inflammatory properties. Nonetheless, the potential of I3C to treat neurodegenerative diseases remains unclear because of its poor ability to penetrate the blood-brain barrier (BBB). Because polymer-based drug delivery systems stabilized by surfactants have been intensively utilized as a strategy to cross the blood-brain barrier, we prepared I3C-loaded poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) that were stabilized by Tween 80 (T80) (I3C-PLGA-T80-NPs) and examined their neuroprotective potential in vitro. We prepared I3C-PLGA-T80-NPs with an oil-in-water (o/w) emulsion solvent evaporation technique and confirmed their successful synthesis with both transmission electron microscopy and Fourier transform-infrared spectroscopy. I3C-PLGA-T80-NPs were then used to treat PC12 neuronal cells injured by glutamate excitotoxicity (GE) and examined the resulting survival rates compared with PC12 cells treated with I3C only. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay revealed higher survival rates in I3C-PLGA-T80-NPs-treated cells after GE injury compared with those treated with I3C only. Furthermore, I3C-PLGA-T80-NPs decreased the levels of reactive oxygen species (ROS) and apoptosis-related enzymes (Caspase-3 and -8) in GE-damaged neuronal cells. Taken together, I3C-PLGA-T80-NPs might possess neuroprotective effects against GE through ROS scavenging and subsequent apoptosis blockage. PMID:26726441

  2. Effects of blending poly(D,L-lactide) with poly(ethylene glycol) on the higher-oder crystalline structures of poly(ethylene glycol) as revealed by small-angle X-ray scattering

    NASA Astrophysics Data System (ADS)

    Tien, N. D.; Hoa, T. P.; Kimura, G.; Yamashiro, Y.; Fujiwara, H.; Mochizuki, M.; Sasaki, S.; Sakurai, S.

    2011-01-01

    Effects of blending poly(lactic acid) (PLA) with poly(ethylene glycol) (PEG) on higher-order crystalline structures of PEG were examined using small-angle X-ray scattering (SAXS). For this purpose, the fact that two polymers are both crystalline makes situtation much complicated. To simplify, non-crystalline PLA is suitable. Thus, we used poly(D,L-lactic acid) (DLPLA), which is random copolymer comprising D- and L-lactic acid moieties. Multiple scattering peaks arising from the regular crystalline lamellar structure were observed for the PEG homopolymer and the blends. Surprisingly, the structure is much more regular for the blend DLPLA/PEG at composition of 20/80 wt.% than for the PEG homopolymer. Also for this blend sample as well as for a PEG homopolymer, very peculiar SAXS profiles were observed just 1°C below Tm of PEG. This is found to be a particle scattering of plate-like objects, which has never been reported for polymer blends or crystalline polymers. Futhermore, it was found that there was strong hysteresis of the higher-order structure formation.

  3. Miscibility and degradability of poly(lactic acid)poly(ethylene oxide)/poly(ethylene glycol) blends

    SciTech Connect

    Yue, C.L.; Dave, V.; Gross, R.A.; McCarthy, S.P.

    1995-12-01

    Poly(lactic acid) [PLA] was melt blended with polyethylene(oxide) [PEG] and poly(ethylene glycol) [PEG] in different compositions to form blown films. It was determined that PLA was miscible with PEO in all compositions. Based on Gordon-Taylor equation, it was determined that the interactions between PLA and PEO is stronger than PEG. The addition of low molecular weight PEG improved the elongation and tear strength of the blends. Enzymatic degradation results shows that the weight loss of all the samples was more than 80% of the initial weight in 48 hours.

  4. Thermal properties of poly (lactic acid)/milkweed composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...

  5. GAS PERMEATION PROPERTIES OF POLY(LACTIC ACID). (R826733)

    EPA Science Inventory

    Abstract

    The need for the development of polymeric materials based on renewable resources has led to the development of poly(lactic acid) (PLA) which is being produced from a feedstock of corn rather than petroleum. The present study examines the permeation of nitrogen...

  6. Miscibility and Morphology of Poly(lactic ACID)/POLY(Β-HYDROXYBUTYRATE) Blends

    NASA Astrophysics Data System (ADS)

    Tri Phuong, Nguyen; Guinault, Alain; Sollogoub, Cyrille

    2011-01-01

    The miscibility and morphology of poly(lactic)acid (PLA)/polyβ-hydroxybutyrate (PHB) prepared by melt blending method were investigated by Fourier transform infrared (FTIR), Differential scanning calorimetry (DSC), melt rheology and scanning electron microscopy (SEM) observations. FTIR and DSC methods present some limits to examine the miscibility state of PLA/PHB blends. This drawback can be overcome with the Cole-Cole method by observing the η" = f(η') curves to confirm the miscibility of semicrystalline PLA/ semicrystalline PHB blends. MEB micrographs of fractured surface of blends were also used to investigate the miscibility of these blends.

  7. Polymers with complexing properties. Simple poly(amino acids)

    NASA Technical Reports Server (NTRS)

    Roque, J. M.

    1978-01-01

    The free amino (0.3 equiv/residue) and carboxyl (0.5 equiv/residue) groups of thermal polylysine increased dramatically on treatment with distilled water. The total hydrolysis of such a polymer was abnormal in that only about 50% of the expected amino acids were recovered. Poly (lysine-co-alanine-co-glycine) under usual conditions hydrolyzed completely in 8 hours; whereas, when it was pretreated with diazomethane, a normal period of 24 hours was required to give (nearly) the same amounts of each free amino acid as compared with those obtained from the untreated polymer. The amino groups of the basic thermal poly(amino acids) were sterically hindered. The existence of nitrogen atoms linking two or three chains and reactive groups (anhydride, imine) were proposed.

  8. Poly(amino acid) functionalized maghemite and gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Perego, Davide; Masciocchi, Norberto; Guagliardi, Antonietta; Domínguez-Vera, José Manuel; Gálvez, Natividad

    2013-02-01

    Bimodal MRI/OI imaging probes are of great interest in nanomedicine. Although many organic polymers have been studied thoroughly for in vivo applications, reports on the use of poly(amino acid)s as coating polymers are scarce. In this paper, poly-(d-glutamic acid, d-lysine) (PGL) has been used for coating maghemite and gold nanoparticles. An advantage of this flexible and biocompatible polymer is that, once anchored to the nanoparticle surface, dangling lysine amino groups are available for the incorporation of new functionalities. As an example, Alexa Fluor derivatives have been attached to PGL-coated maghemite nanoparticles to obtain magnetic/fluorescent materials. These dual-property materials could be used as bimodal MRI/OI probes for in vivo imaging.

  9. The influences of elastomer toward degradability of poly (lactic acid)

    NASA Astrophysics Data System (ADS)

    Kaavessina, Mujtahid; Distantina, Sperisa; Chafidz, Achmad; Fadilah, Al-Zahrani, Saeed M.

    2016-02-01

    Poly (lactic acid)/elastomer blends were prepared via direct injection molding with the different weight fractions of elastomer, namely: 0, 10, 20 and 30 wt%. Degradation test of poly (lactic acid) (PLA) was performed by burial in the soil. The physical appearance and thermal properties of the tested specimens were monitored periodically. The presence of elastomer tended to significantly increase the degradability of PLA after buried for 27 weeks. With 30 wt% elastomer, the color and the surface of specimens become more white and rougher due to the degradation. Differential scanning calorimetry (DSC) was used to evaluate thermal properties and crystallinity of all samples. It was found that the melting temperature decreased as the amount of elastomer increased. The crystallinity showed that the degradation of PLA is occurred firstly in amorphous phase.

  10. Controlled release of anti-diabetic drug Gliclazide from poly(caprolactone)/poly(acrylic acid) hydrogels.

    PubMed

    Bajpai, S K; Chand, Navin; Soni, Shweta

    2015-01-01

    Drug Gliclazide (Glz) has limited solubility and low bioavailability. In order to obtain a controlled release of this drug and to improve its bioavailability, the drug has been loaded into poly(caprolactone) (PCL)/poly(acrylic acid) (PAAc) hydrogels, prepared by free radical polymerization of acrylic acid in the presence of poly(caprolactone) in acetone medium using azo-isobutyronitrile as initiator and N,N' methylene bisacrylamide as cross-linking agent. The swelling behaviour of these hydrogels has been investigated in the physiological gastric and intestinal fluids to obtain an optimum composition suitable for delivery of a biologically active compound. The gels were loaded with anti-diabetic drug Glz and a detailed investigation of release of drug has been carried out. Various kinetic models have been applied on the release data. Finally, the Albino wistar rats were treated for Streptozotocin plus nicotinamide - induced diabetes using a Glz-loaded PCL/PAAc hydrogel. The results indicated a fair reduction in the glucose level of rats. PMID:26135033

  11. Biodegradation and Mechanical Properties of Poly(lactic acid)/Poly(butylene succinate) Blends

    NASA Astrophysics Data System (ADS)

    Kobayashi, Satoshi; Sugimoto, Satomi

    Polymer blends were fabricated with poly(lactic acid) (PLA) with better mechanical properties and poly(butylene succinate) (PBSU) with better biodegradable properties to clarify the effect of the blending ratio on the biodegradable and mechanical properties of the blends. The specimens were heat treated to improve the reduction in stiffness due to blending. Hydrolysis and soil burial tests up to 16 weeks were conducted to investigate the biodegradation properties. Young's modulus increased with increasing contents of PLA, whereas tensile strength is lowest in the PLA/PBSU (50/50) polymer blend before biodegradation because of the immiscibility of PLA and PBSU. Young's modulus kept constant up 16 weeks both in the hydrolysis and the soil burial tests. On the other hand, tensile strength decreased remarkably in the hydrolysis tests. The observation results of the specimen surface and the fracture surface indicate that the surface and bulk degradation occur in hydrolysis and soil burial tests, respectively

  12. Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were exami...

  13. Safety evaluation of poly(lactic-co-glycolic acid)/poly(lactic-acid) microspheres through intravitreal injection in rabbits

    PubMed Central

    Rong, Xianfang; Yuan, Weien; Lu, Yi; Mo, Xiaofen

    2014-01-01

    Poly(lactic-co-glycolic acid) (PLGA) and/or poly(lactic-acid) (PLA) microspheres are important drug delivery systems. This study investigated eye biocompatibility and safety of PLGA/PLA microspheres through intravitreal injection in rabbits. Normal New Zealand rabbits were randomly selected and received intravitreal administration of different doses (low, medium, or high) of PLGA/PLA microspheres and erythropoietin-loaded PLGA/PLA microspheres. The animals were clinically examined and sacrificed at 1, 2, 4, 8, and 12 weeks postadministration, and retinal tissues were prepared for analysis. Retinal reactions to the microspheres were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end staining and glial fibrillary acidic protein immunohistochemistry. Retinal structure changes were assessed by hematoxylin and eosin staining and transmission electron microscopy. Finally, retinal function influences were explored by the electroretinography test. Terminal deoxynucleotidyl transferase-mediated dUTP nick end staining revealed no apoptotic cells in the injected retinas; immunohistochemistry did not detect any increased glial fibrillary acidic protein expression. Hematoxylin and eosin staining and transmission electron microscopy revealed no micro- or ultrastructure changes in the retinas at different time points postintravitreal injection. The electroretinography test showed no significant influence of scotopic or photopic amplitudes. The results demonstrated that PLGA/PLA microspheres did not cause retinal histological changes or functional damage and were biocompatible and safe enough for intravitreal injection in rabbits for controlled drug delivery. PMID:25028546

  14. Conformation of poly(γ-glutamic acid) in aqueous solution.

    PubMed

    Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε(*) , however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random-coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media. PMID:26574908

  15. Patterned biofunctional poly(acrylic acid) brushes on silicon surfaces.

    PubMed

    Dong, Rong; Krishnan, Sitaraman; Baird, Barbara A; Lindau, Manfred; Ober, Christopher K

    2007-10-01

    Protein patterning was carried out using a simple procedure based on photolithography wherein the protein was not subjected to UV irradiation and high temperatures or contacted with denaturing solvents or strongly acidic or basic solutions. Self-assembled monolayers of poly(ethylene glycol) (PEG) on silicon surfaces were exposed to oxygen plasma through a patterned photoresist. The etched regions were back-filled with an initiator for surface-initiated atom transfer radical polymerization (ATRP). ATRP of sodium acrylate was readily achieved at room temperature in an aqueous medium. Protonation of the polymer resulted in patterned poly(acrylic acid) (PAA) brushes. A variety of biomolecules containing amino groups could be covalently tethered to the dense carboxyl groups of the brush, under relatively mild conditions. The PEG regions surrounding the PAA brush greatly reduced nonspecific adsorption. Avidin was covalently attached to PAA brushes, and biotin-tagged proteins could be immobilized through avidin-biotin interaction. Such an immobilization method, which is based on specific interactions, is expected to better retain protein functionality than direct covalent binding. Using biotin-tagged bovine serum albumin (BSA) as a model, a simple strategy was developed for immobilization of small biological molecules using BSA as linkages, while BSA can simultaneously block nonspecific interactions. PMID:17880179

  16. Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance.

    PubMed

    Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin

    2015-08-19

    Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications. PMID:26222398

  17. Poly(trimethylene carbonate)/Poly(malic acid) Amphiphilic Diblock Copolymers as Biocompatible Nanoparticles.

    PubMed

    Barouti, Ghislaine; Khalil, Ali; Orione, Clement; Jarnouen, Kathleen; Cammas-Marion, Sandrine; Loyer, Pascal; Guillaume, Sophie M

    2016-02-18

    Amphiphilic polycarbonate-poly(hydroxyalkanoate) diblock copolymers, namely, poly(trimethylene carbonate) (PTMC)-b-poly(β-malic acid) (PMLA), are reported for the first time. The synthetic strategy relies on commercially available catalysts and initiator. The controlled ring-opening polymerization (ROP) of trimethylene carbonate (TMC) catalyzed by the organic guanidine base 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), associated with iPrOH as an initiator, provided iPrO-PTMC-OH, which served as a macroinitiator in the controlled ROP of benzyl β-malolactonate (MLABe) catalyzed by the neodymium triflate salt (Nd(OTf)3). The resulting hydrophobic iPrO-PTMC-b-PMLABe-OH copolymers were then hydrogenolyzed into the parent iPrO-PTMC-b-PMLA-OH copolymers. A range of well-defined copolymers, featuring different sizes of segments (Mn,NMR up to 9300 g mol(-1) ; ÐM =1.28-1.40), were thus isolated in gram quantities, as evidenced by NMR spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, and contact angle analyses. Subsequently, PTMC-b-PMLA copolymers with different hydrophilic weight fractions (11-75 %) self-assembled in phosphate-buffered saline upon nanoprecipitation into well-defined nano-objects with Dh =61-176 nm, a polydispersity index <0.25, and a negative surface charge, as characterized by dynamic light scattering and zeta-potential analyses. In addition, these nanoparticles demonstrated no significant effect on cell viability at low concentrations, and a very low cytotoxicity at high concentrations only for PTMC-b-PMLA copolymers exhibiting hydrophilic fractions over 47 %, thus illustrating the potential of these copolymers as promising nanoparticles. PMID:26791328

  18. Investigation of electrochemical properties of a poly(vinyl alcohol)/poly(acrylic acid) polymer blend

    SciTech Connect

    DeSantis, C.O.; Seliskar, C.; Heineman, W.R.

    1995-12-31

    Chemical sensors have wide applications in medicine, environmental monitoring, industrial applications, and others because of their versatility, ruggedness, sensitivity, selectivity, and economy. Electrochemical sensors are constructed by using a conducting medium, in this case graphite, and applying a constant potential while measuring changes in the current. Polymers are used for electrochemical sensors to exclude interferents from the electrode surface, to preconcentrate the analyte near the electrode, and in some cases to provide a matrix for the immobilization of analytes, such as enzymes. These functions of the polymer can serve to improve the detection limit of the sensor. This project involves the evaluation of a new polymer for electrode modification. The poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) polymer was originally developed as an ion exchanger for use in space batteries. It has also been used in wastewater cleanup because it will concentrate heavy metals in the presence of calcium ion. This polymer is also optically clear, so it can potentially be used for an optical sensor. We are interested in investigating the ion exchange properties of the PVA/PAA polymer, as well as the ability of this polymer to preconcentrate and exclude analytes on the basis of size, charge, and hydrophilic/hydrophobic interactions.

  19. Antimicrobial activity of poly(vinyl alcohol)-poly(acrylic acid) electrospun nanofibers.

    PubMed

    Santiago-Morales, Javier; Amariei, Georgiana; Letón, Pedro; Rosal, Roberto

    2016-10-01

    Electrospun nanofibers were prepared from blends of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA). The fibers were stabilized by heat curing at 140°C via anhydride and ketone formation and crosslinking esterification. The antimicrobial effect was assessed using strains of Escherichia coli and Staphylococcus aureus by tracking their capacity to form colonies and their metabolic impairment upon contact with PAA/PVA membranes. Membranes containing >35wt.% PAA displayed significant antibacterial activity, which was particularly high for the gram-positive S. aureus. All membranes were negatively charged, with surface ζ-potential in the (-34.5)-(-45.6)mV range, but the electrostatic interaction with the negatively charged cells was not the reason for the antimicrobial effect. Neither pH reduction nor the passing of non-crosslinked polymers to the solution affected microbial growth. The antibacterial activity was attributed to the chelation of the divalent cations stabilizing the outer cell membrane. The effect on gram-positive bacteria was attributed to the destabilization of the peptidoglycan layer. The sequestration of divalent cations was demonstrated with experiments in which calcium and a chelating agent were added to the cultures in contact with membranes. The damage to bacterial cells was tracked by measuring their surface charge and the evolution of intracellular calcium during the early stages after contact with PAA/PVA membranes. PMID:27318959

  20. Molecular Basis of the Receptor Interactions of Polysialic Acid (polySia), polySia Mimetics, and Sulfated Polysaccharides.

    PubMed

    Zhang, Ruiyan; Loers, Gabriele; Schachner, Melitta; Boelens, Rolf; Wienk, Hans; Siebert, Simone; Eckert, Thomas; Kraan, Stefan; Rojas-Macias, Miguel A; Lütteke, Thomas; Galuska, Sebastian P; Scheidig, Axel; Petridis, Athanasios K; Liang, Songping; Billeter, Martin; Schauer, Roland; Steinmeyer, Jürgen; Schröder, Jens-Michael; Siebert, Hans-Christian

    2016-05-01

    Polysialic acid (polySia) and polySia glycomimetic molecules support nerve cell regeneration, differentiation, and neuronal plasticity. With a combination of biophysical and biochemical methods, as well as data mining and molecular modeling techniques, it is possible to correlate specific ligand-receptor interactions with biochemical processes and in vivo studies that focus on the potential therapeutic impact of polySia, polySia glycomimetics, and sulfated polysaccharides in neuronal diseases. With this strategy, the receptor interactions of polySia and polySia mimetics can be understood on a submolecular level. As the HNK-1 glycan also enhances neuronal functions, we tested whether similar sulfated oligo- and polysaccharides from seaweed could be suitable, in addition to polySia, for finding potential new routes into patient care focusing on an improved cure for various neuronal diseases. The knowledge obtained here on the structural interplay between polySia or sulfated polysaccharides and their receptors can be exploited to develop new drugs and application routes for the treatment of neurological diseases and dysfunctions. PMID:27136597

  1. Poly(lactic acid) / Poly(ethylene glycol) blends: Mechanical, thermal and morphological properties

    NASA Astrophysics Data System (ADS)

    Bijarimi, M.; Ahmad, S.; Rasid, R.; Khushairi, M. A.; Zakir, M.

    2016-04-01

    The poly(lactic acid) (PLA) was melt blended with linear polyethylene glycol (PEG) in an effort to increase the toughness of PLA. Melt blending was carried out in an internal mixer at 180 °C mixing temperature with 50 rpm for 15 minutes. The blends were characterized in terms of mechanical, thermal and morphological properties. It was found that tensile and flexural strength, stiffness and notched Izod impact strength decreased significantly when the PEG was added to the PLA matrix at 2.5-10% of PEG concentrations. Both glass transition and melting temperatures (Tg and Tm) lowered as the concentration of PEG was increased. Moreover, it was noted that the PLA/PEG blends showed a lower onset and peak degradation temperatures but with lower final degradation temperature as compared to the neat PLA. The morphological analysis revealed that the PEG was dispersed as droplets in the PLA matrix with a clear boundary between PLA matrix and PEG phases.

  2. PolyGuanine methacrylate cryogels for ribonucleic acid purification.

    PubMed

    Köse, Kazım; Uzun, Lokman

    2016-05-01

    The isolation and purification of ribonucleic acid have attracted attention recently for the understanding of the functions in detail because of the necessity for the treatment of genetic diseases. In this study, guanine-incorporated polymeric cryogels were developed to obtain highly purified ribonucleic acid. The satisfactory purification performance was achieved with the guanine-incorporated poly (2-hydroxyethyl methacrylate-guanine methacrylate) cryogels. The most crucial advantages to use guanine as a functional monomer are to obtain a real natural interaction between guanine on the polymeric material and cytosine on the ribonucleic acid. Moreover, using cryogel with a highly porous structure and high swelling ratio provide advantages of getting more water within the structure to get more analyte to interact. The characterization of cryogels has proved the success of the synthesis and the perfect natural interaction to be taken place between the ligand (guanine methacrylate) and the cytosine in the ribonucleic acid molecules. Although the pores within the structure of cryogels are small, they provide efficient and fast adsorption. The chromatographic separation performance was investigated for different conditions (pH, temperature etc.). The desorption ratio and reusability were also analyzed at the end of the five adsorption-desorption cycles with no significant changes. PMID:27004613

  3. Transient Current Behaviour of Poly (p-hydroxybenzoic acid-co-ethylene terephthalate) Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Yarramaneni, Sridharbabu; Sharma, Anu; Quamara, J. K.

    2011-07-01

    Transient current behaviour of pristine Poly (p-hydroxybenzoic acid-co-ethylene terephthalate) Liquid crystal polymer which is a copolymer of poly ethylene terephthalate and poly p-hydroxybenzoic acid referred as PET/x.PHB polymer liquid crystals have been studied at different biasing electric fields ranging from 13 kV/cm to 104.3 kV/cm and at temperatures 120° C and 250° C for molar ratio x =0.8.

  4. Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)-poly(vinyl alcohol)/poly(acrylic acid) interpenetrating polymer networks for improving optrode-neural tissue interface in optogenetics.

    PubMed

    Lu, Yi; Li, Yanling; Pan, Jianqing; Wei, Pengfei; Liu, Nan; Wu, Bifeng; Cheng, Jinbo; Lu, Caiyi; Wang, Liping

    2012-01-01

    The field of optogenetics has been successfully used to understand the mechanisms of neuropsychiatric diseases through the precise spatial and temporal control of specific groups of neurons in a neural circuitry. However, it remains a great challenge to integrate optogenetic modulation with electrophysiological and behavioral read out methods as a means to explore the causal, temporally precise, and behaviorally relevant interactions of neurons in the specific circuits of freely behaving animals. In this study, an eight-channel chronically implantable optrode array was fabricated and modified with poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)-poly(vinyl alcohol)/poly(acrylic acid) interpenetrating polymer networks (PEDOT/PSS-PVA/PAA IPNs) for improving the optrode-neural tissue interface. The conducting polymer-hydrogel IPN films exhibited a significantly higher capacitance and lower electrochemical impedance at 1 kHz as compared to unmodified optrode sites and showed significantly improved mechanical and electrochemical stability as compared to pure conducting polymer films. The cell attachment and neurite outgrowth of rat pheochromocytoma (PC12) cells on the IPN films were clearly observed through calcein-AM staining. Furthermore, the optrode arrays were chronically implanted into the hippocampus of SD rats after the lentiviral expression of synapsin-ChR2-EYFP, and light-evoked, frequency-dependant action potentials were obtained in freely moving animals. The electrical recording results suggested that the modified optrode arrays showed significantly reduced impedance and RMS noise and an improved SNR as compared to unmodified sites, which may have benefited from the improved electrochemical performance and biocompatibility of the deposited IPN films. All these characteristics are greatly desired in optogenetic applications, and the fabrication method of conducting polymer-hydrogel IPNs can be easily integrated with other modification methods to build a

  5. NOVEL POLY-GLUTAMIC ACID FUNCTIONALIZED MICROFILTRATION MEMBRANES FOR SORPTION OF HEAVY METALS AT HIGH CAPACITY

    EPA Science Inventory

    Various sorbent/ion exchange materials have been reported in the literature for metal ion entrapment. We have developed a highly innovative and new approach to obtain high metal pick-up utilizing poly-amino acids (poly-L-glutamic acid, 14,000 MW) covalently attached to membrane p...

  6. Radiation synthesis of nanosilver nanohydrogels of poly(methacrylic acid)

    NASA Astrophysics Data System (ADS)

    Gupta, Bhuvanesh; Gautam, Deepti; Anjum, Sadiya; Saxena, Shalini; Kapil, Arti

    2013-11-01

    Nanosilver nanohydrogels (nSnH) of poly(methacrylic acid) were synthesized and stabilized using gamma irradiation. The main objective of this study was to develop silver nanoparticles and to evaluate the antimicrobial activity. Radiation helps in the polymerization, crosslinking and reduction of silver nitrate as well. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel network by water in oil nanoemulsion polymerization and were evaluated by dynamic light scattering (DLS) and transmission electron microscopy (TEM) respectively. TEM showed almost spherical and uniform distribution of silver nanoparticles through the hydrogel network. The mean size of silver nanoparticles ranging is 10-50 nm. The nanohydrogels showed good swelling in water. Antibacterial studies of nSnH suggest that it can be a good candidate as coating material in biomedical applications.

  7. Interfacial Shear Strength Evaluation of Jute/Poly(Lactic Acid)

    NASA Astrophysics Data System (ADS)

    Kobayashi, Satoshi; Yamamoto, Tatsuro; Nakai, Asami

    In order to evaluate the interfacial shear strength between fiber bundle and matrix of jute/poly(lactic acid) (PLA), a fiber bundle pull-out test method is proposed. Shear stress distribution was calculated based on the parabolic shear-lag analysis. Fiber bundle pull-out tests were conducted to evaluate the effects of molding condition on the interfacial shear strength. The interfacial shear strength increased with increasing molding temperature up to 185°C. Then gradual decrease in the interfacial shear strength with molding temperature was observed. Similar tendency was also observed in the effect of molding time, whereas the interfacial shear strength decreased with increasing molding pressure. Comparing the result of the tensile tests in the previous study, interfacial shear strength has corelations with tensile strength.

  8. Enhancement effect of poly(amino acid)s on insulin uptake in alveolar epithelial cells.

    PubMed

    Oda, Keisuke; Yumoto, Ryoko; Nagai, Junya; Katayama, Hirokazu; Takano, Mikihisa

    2012-01-01

    In this study, we elucidated the effect of poly(amino acid)s such as poly-L-ornithine (PLO) on FITC-insulin uptake in cultured alveolar type II epithelial cells, RLE-6TN. FITC-insulin uptake by RLE-6TN cells as well as its cell surface binding was markedly increased by PLO without cytotoxicity. The uptake of FITC-insulin in the presence of PLO was shown to be mediated by endocytosis, but in contrast to the uptake in the absence of PLO, the contribution of macropinocytosis emerged. Colocalization of FITC-insulin and LysoTracker Red was observed by confocal laser scanning microscopy both in the absence and presence of PLO, indicating that FITC-insulin was partly targeted to lysosomes in the cells and degraded. The half-life of the intracellular degradation of FITC-insulin was, however, prolonged by the presence of PLO. PLO also stimulated the uptake of other FITC-labeled compounds. Among them, the enhancement effects of PLO on FITC-albumin and FITC-insulin uptake were prominent. The effect of PLO on insulin absorption was also examined in in-vivo pulmonary administration in rats, and co-administration of PLO enhanced the hypoglycemic action of insulin. These findings suggest that co-administration of poly(amino acid)s such as PLO is a useful strategy for enhancing insulin uptake by alveolar epithelial cells and subsequent absorption from the lung. PMID:22510869

  9. Generation of C3- and C2-deuterated L-lactic acid by human erythrocytes exposed to D-[1-13C]glucose, D-[2-13C]glucose and D-[6-13C]glucose in the presence of D2O.

    PubMed

    Malaisse, W J; Biesemans, M; Willem, R

    1994-05-01

    1. The generation of C2- and C3-deuterated L-lactate was monitored by 13C NMR in human erythrocytes exposed to D-[1-13C]glucose, D-[2-13C]glucose or D-[6-13C]glucose and incubated in a medium prepared in D2O. 2. The results suggested that the deuteration of the C1 of D-fructose 6-phosphate in the phosphoglucoisomerase reaction, the deuteration of the C1 of D-glyceraldehyde-3-phosphate in the sequence of reactions catalyzed by triose phosphate isomerase and aldolase and the deuteration of the C3 of pyruvate in the reaction catalyzed by pyruvate kinase were all lower than expected from equilibration with D2O. 3. Moreover, about 40% of the molecules of pyruvate generated by glycolysis apparently underwent deuteration on their C3 during interconversion of the 2-keto acid and L-alanine in the reaction catalyzed by glutamate-pyruvate transaminase. 4. The occurrence of the latter process was also documented in cells exposed to exogenous [3-13C]pyruvate. 5. This methodological approach is proposed to provide a new tool to assess in intact cells the extent of back-and-forth interconversion of selected metabolic intermediates. PMID:8005354

  10. Biodegradable water absorbent synthesized from bacterial poly(amino acid)s.

    PubMed

    Kunioka, Masao

    2004-03-15

    Biodegradable hydrogels prepared by gamma-irradiation from microbial poly(amino acid)s have been studied. pH-Sensitive hydrogels were prepared by the gamma-irradiation of poly(gamma-glutamic acid) (PGA) produced by Bacillus subtilis and poly(epsilon-lysine) (PL) produced by Streptomyces albulus in aqueous solutions. When the gamma-irradiation dose was 19 kGy or more, and the concentration of PGA in water was 2 wt.-% or more, transparent hydrogels could be produced. For the 19 kGy dose, the produced hydrogel was very weak, however, the specific water content (wt. of absorbed water/wt. of dry hydrogel) of this PGA hydrogel was approximately 3,500. The specific water content decreased to 200, increasing when the gamma-irradiation dose was over 100 kGy. Under acid conditions or upon the addition of electrolytes, the PGA hydrogels shrunk. The PGA hydrogel was pH-sensitive and the change in the volume of the hydrogel depended on the pH value outside the hydrogel in the swelling medium. This PGA hydrogel was hydrodegradable and biodegradable. A new novel purifier reagent (coagulant), made from the PGA hydrogels, for contaminated turbid water has been found and developed by Japanese companies. A very small amount of this coagulant (only 2 ppm in turbid water) with poly(aluminum chloride) can be used for the purification of turbid water. A PL aqueous solution also can change into a hydrogel by gamma-irradiation. The specific water content of the PL hydrogel ranged from 20 to 160 depending on the preparation conditions. Under acid conditions, the PL hydrogel swelled because of the ionic repulsion of the protonated amino groups in the PL molecules. The rate of enzymatic degradation of the respective PL hydrogels by a neutral protease was much faster than the rate of simple hydrolytic degradation. PMID:15468223

  11. Poly(acrylic acid) to induce competitive crystallization of a theophylline/oxalic acid cocrystal and a theophylline polymorph

    NASA Astrophysics Data System (ADS)

    Jang, Jisun; Kim, Il Won

    2016-01-01

    Polymeric additives to induce competitive crystallization of pharmaceutical compounds were explored. A cocrystal of theophylline and oxalic acid was used as a model system, and poly(acrylic acid), poly(caprolactone), and poly(ethylene glycol) were the additives. The cocrystal formation was selectively hindered with addition of poly(acrylic acid). First the size of the cocrystals were reduced, and eventually the cocrystallization was inhibited to generate neat theophylline crystals. The theophylline crystals were of a distinctively different crystal structure from known polymorphs, based on powder X-ray diffraction. They were also obtained in nanoscale size, when millimeter-scale crystals formed without poly(acrylic acid). Polymeric additives that could form specific interactions with crystallizing compounds seem to be useful tools for the phase and size control of pharmaceutical crystals.

  12. Reversible Bacterial Adhesion on Mixed Poly(dimethylaminoethyl methacrylate)/Poly(acrylamidophenyl boronic acid) Brush Surfaces.

    PubMed

    Xiong, Xinhong; Wu, Zhaoqiang; Yu, Qian; Xue, Lulu; Du, Jun; Chen, Hong

    2015-11-10

    A simple and versatile method for the preparation of surfaces to control bacterial adhesion is described. Substrates were first treated with two catechol-based polymerization initiators, one for thermal initiation and one for visible-light photoinitiation. Graft polymerization in sequence of dimethylaminoethyl methacrylate (DMAEMA) and 3-acrylamidebenzene boronic acid (BA) from the surface-bound initiators to form mixed polymer brushes on the substrate was then carried out. The PDMAEMA grafts were thermally initiated and the PBA grafts were visible-light-photoinitiated. Gold, poly(vinyl chloride) (PVC), and poly(dimethylsiloxane) (PDMS) were used as model substrates. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), and ellipsometry analysis confirmed the successful grafting of PDMAEMA/PBA mixed brushes. We demonstrated that the resulting surfaces showed charge-reversal properties in response to change of pH. The transition in surface charge at a specific pH allowed the surface to be reversibly switched from bacteria-adhesive to bacteria-resistant. At pH 4.5, below the isoelectric points (IEP, pH 5.3) of the mixed brushes, the surfaces are positively charged and the negatively charged Gram-positive S. aureus adheres at high density (2.6 × 10(6) cells/cm(2)) due to attractive electrostatic interactions. Subsequently, upon increasing the pH to 9.0 to give negatively charged polymer brush surface, ∼90% of the adherent bacteria are released from the surface, presumably due to repulsive electrostatic interactions. This approach provides a simple method for the preparation of surfaces on which bacterial adhesion can be controlled and is applicable to a wide variety of substrates. PMID:26509287

  13. Laboratory composting of extruded poly(lactic acid) sheets.

    PubMed

    Ghorpade, V M; Gennadios, A; Hanna, M A

    2001-01-01

    Composting of extruded poly(lactic acid) (PLA) in combination with pre-composted yard waste in a laboratory composting system was studied. Yard waste and PLA mixtures containing 0%, 10%, or 30% PLA (dry weight basis) were placed in composting vessels for four weeks. Exhaust gases were analyzed for carbon dioxide concentration twice per week. After the first week, significantly greater (P < 0.05) amounts of carbon dioxide were generated in vessels with 10% or 30% PLA than in control (0% PLA) vessels. Data indicated that microbial degradation of PLA occurred. There was no significant difference (P > 0.05) in carbon dioxide emission between 10% and 30% PLA mixtures. Compost pH dropped (from 6.0 to 4.0) after 4 weeks of composting for 30% PLA, but remained unchanged (6.3) for 0% or 10% PLA. Most likely, in the case of 30% PLA, substantial chemical hydrolysis and lactic acid generation lowered the compost pH. The lowered pH likely suppressed microbial activity, thus explaining the lack of difference in carbon dioxide emissions between 10% and 30% PLA mixtures. Gel permeation chromatography showed a notable decrease in PLA molecular weight as a result of composting. It was demonstrated that PLA can be efficiently composted when added in small amounts (<30% by weight) to pre-composted yard waste. PMID:11315811

  14. Stability of Poly(α-L Glutamic Acid).

    NASA Astrophysics Data System (ADS)

    Choi, Peter; Chen, Y. Z.; Prohofsky, E. W.

    1996-03-01

    For the protein to go to their folded biologically active state, it must first undergo formation of the stabilizing α-helix structure. Taking the repeating unit cells of Glutamic acid in an α-helix structure, the analysis can be made of the vibrational dynamics of the Poly(α-L Glutamic acid). The method used was mean field, modified, self-consistent phonon theory (MSPA) developed by Prohofsky et al. The modes contributing to the fluctuations of the α-helix hydrogen bonds were analyzed yielding the break down probability from the room temperature to the critical temperature Tc where the hydrogen bond probability is over 0.5. The inverse proportionality of the opening bond probability to the relaxation time τ * was then used to compare our results to ultra sonic and electric-field jump experiments. These experiments were done at temperatures ranging from 295 K to 310 K. The data obtained from these experiments agrees well with the temperature dependent MSPA open bond probabilities with correlation constant of (1.6 ± 0.1)x10e-8. Our calculation also yielded critical melting temperature of Tc=332 K.

  15. Elastomeric electrospun scaffolds of poly(L-lactide-co-trimethylene carbonate) for myocardial tissue engineering.

    PubMed

    Mukherjee, Shayanti; Gualandi, Chiara; Focarete, Maria Letizia; Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Raghunath, Michael; Ramakrishna, Seeram

    2011-07-01

    In myocardial tissue engineering the use of synthetically bioengineered flexible patches implanted in the infarcted area is considered one of the promising strategy for cardiac repair. In this work the potentialities of a biomimetic electrospun scaffold made of a commercial copolymer of (L)-lactic acid with trimethylene carbonate (P(L)LA-co-TMC) are investigated in comparison to electrospun poly(L)lactic acid. The P(L)LA-co-TMC scaffold used in this work is a glassy rigid material at room temperature while it is a rubbery soft material at 37 °C. Mechanical characterization results (tensile stress-strain and creep-recovery measurements) show that at 37 °C electrospun P(L)LA-co-TMC displays an elastic modulus of around 20 MPa and the ability to completely recover up to 10% of deformation. Cell culture experiments show that P(L)LA-co-TMC scaffold promotes cardiomyocyte proliferation and efficiently preserve cell morphology, without hampering expression of sarcomeric alpha actinin marker, thus demonstrating its potentialities as synthetic biomaterial for myocardial tissue engineering. PMID:21617996

  16. Preparation and Biophysical Characterization of Poly(amidoamine) Dendrimer-Poly(acrylic acid) Graft.

    PubMed

    Dung, Tran Huu; Do, Le Thanh; Loan, Ta Thi; Yoo, Hoon

    2015-01-01

    A series of PAMAM dendrimer generation 5-poly(acrylic acid) grafts were prepared to evaluate the potential use of dendritic grafts as a drug encapsulated nanocarrier. The structural features of the synthesized polymer graft were identified by FT-IR and 1H-NMR spectra and the biophysical properties were characterized by measuring its particle size and zeta potential. The prepared dendrimer G5-PAA grafts had particle size in the range of 600 to 900 nm and the size increased proportionally with the number of PAA on dendrimer surface. The electrostatic property of the dendrimer G5-PAA, carried out by HPLC reversed phase column analysis and the measurement of zeta potential, revealed that both migration time and zeta potential were dependent on the number of grafted PAA. The number of free amino groups on dendrimer G5-PAA, determined quantitatively by fluorescamine assay, was in a reverse order with the reaction mole ratio of dendrimer to PAA. In addition, dendrimer G5-PAA showed a pH-dependent solubility in aqueous solution with characteristic pH region of solubility, depending on the dendrimer generation. The observed biophysical properties indicate that PAMAM dendrimer G5-PAA is promising as a drug encapsulated nanocarrier. PMID:26328427

  17. Investigation of the doping efficiency of poly(styrene sulfonic acid) in poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) dispersions by capillary electrophoresis.

    PubMed

    Diah, Anang W M; Quirino, Joselito P; Belcher, Warwick; Holdsworth, Clovia I

    2014-07-01

    CE can efficiently separate poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) complexes and free PSS in dispersions and can be used to estimate the degree of PSS doping. We investigated the doping efficiency of PSS on PEDOT in dispersions using CE and its effect on the conductivity of the resulting PEDOT/PSS films. Results of this study indicate that dispersions containing 1:2.5-3 EDOT:PSS feed ratio (by weight) exhibiting 72-73% PSS doping generate highly processable and highly conductive films. Conductivity can be optimized by limiting the time of reaction to 12 h. At this point of the reaction, the PEDOT/PSS segments, appearing as broad band in the electropherogram, could still exist in an extended coil conformation favoring charge transport resulting in high conductivity. Above a threshold PEDOT length formed at reaction times longer than 12 h, the PEDOT/PSS complex, appearing as spikes in the electropherogram, most likely have undergone a conformational change to coiled core-shell structure restricting charge transport resulting in low conductivity. The optimal conductivity (5.2 S/cm) of films from dispersions synthesized for 12 h is significantly higher than those from its commercial equivalent Clevios P and other reported values obtained under similar conditions without the addition of codopants. PMID:24782292

  18. Properties of wheat gluten/poly(lactic acid) laminates.

    PubMed

    Cho, Sung-Woo; Gällstedt, Mikael; Hedenqvist, Mikael S

    2010-06-23

    Laminates of compression-molded glycerol-plasticized wheat gluten (WG) films surrounded and supported by poly(lactic acid) (PLA) films have been produced and characterized. The objective was to obtain a fully renewable high gas barrier film with sufficient mechanical integrity to function in, for example, extrusion-coating paper/board applications. It was shown that the lamination made it possible to make films with a broad range of glycerol contents (0-30 wt %) with greater strength than single unsupported WG films. The low plasticizer contents yielded laminates with very good oxygen barrier properties. In addition, whereas the unsupported WG films had an immeasurably high water vapor transmission rate (WVTR), the laminate showed values that were finite and surprisingly, in several cases, also lower than that of PLA. Besides being a mechanical support (as evidenced by bending and tensile data) and a shield between the WG and surrounding moisture, the PLA layer also prevented the loss of the glycerol plasticizer from the WG layer. This was observed after the laminate had been aged on an "absorbing" blotting paper for up to 17 weeks. The interlayer adhesion (peel strength) decreased with decreasing glycerol content and increasing WG film molding temperature (130 degrees C instead of 110 degrees C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 degrees C) did not, however, have a major effect on the final peel strength. PMID:20504031

  19. Poly (lactic acid) (PLA)/clay/wood nanocomposites

    NASA Astrophysics Data System (ADS)

    Meng, Qingkai

    Poly (lactic acid) (PLA) is a promising substitute for conventional petroleum-based polymer materials as a result of its environmentally benign quality and suitable physical properties. However, there are also problems associated with properties, such as brittleness, low heat deflection temperature, low melt viscosity, as well as cost that prevent wide-range applications of PLA. This work reports on melt extrusion preparation of PLA/clay/wood nanocomposites involving various compatibilizers, resulting in remarkable improvements in mechanical as well as in thermal material properties. In particular, the tensile and flexural moduli of PLA/clay/wood nanocomposites with 30 wt. % wood flour and 5 wt. % nanoclay respectively increased from 3.75 to 7.08 GPa and from 3.83 to 6.01 GPa compared to neat PLA. The thermal decomposition temperature improved by about 10°C compared to that of PLA/wood composites. A mathematical model was developed based on Eshelby's equivalent inclusion method and Mori-Tanaka's background analysis to successfully predict longitudinal elastic moduli of complex structured nanocomposite materials.

  20. Interaction of photosensitive surfactant with DNA and poly acrylic acid.

    PubMed

    Zakrevskyy, Yuriy; Cywinski, Piotr; Cywinska, Magdalena; Paasche, Jens; Lomadze, Nino; Reich, Oliver; Löhmannsröben, Hans-Gerd; Santer, Svetlana

    2014-01-28

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes' properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate - for the first time - complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules. PMID:25669583

  1. Supermacroporous chemically cross-linked poly(aspartic acid) hydrogels.

    PubMed

    Gyarmati, Benjámin; Mészár, E Zsuzsanna; Kiss, Lóránd; Deli, Mária A; László, Krisztina; Szilágyi, András

    2015-08-01

    Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by a solid-liquid phase separation technique, cryogelation, to achieve a supermacroporous interconnected pore structure. The precursor polymer of PASP, polysuccinimide (PSI) was cross-linked below the freezing point of the solvent and the forming crystals acted as templates for the pores. Dimethyl sulfoxide was chosen as solvent instead of the more commonly used water. Thus larger temperatures could be utilized for the preparation and the drawback of increase in specific volume of water upon freezing could be eliminated. The morphology of the hydrogels was characterized by scanning electron microscopy and interconnectivity of the pores was proven by the small flow resistance of the gels. Compression tests also confirmed the interconnected porous structure and the complete re-swelling and shape recovery of the supermacroporous PASP hydrogels. The prepared hydrogels are of interest for several biomedical applications as scaffolding materials because of their cytocompatibility, controllable morphology and pH-responsive character. PMID:25922304

  2. Interaction of photosensitive surfactant with DNA and poly acrylic acid

    SciTech Connect

    Zakrevskyy, Yuriy Paasche, Jens; Lomadze, Nino; Santer, Svetlana; Cywinski, Piotr; Cywinska, Magdalena; Reich, Oliver; Löhmannsröben, Hans-Gerd

    2014-01-28

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes’ properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate – for the first time – complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules.

  3. Preparation and characterization of reactive blends of poly(lactic acid), poly(ethylene-co-vinyl alcohol), and poly(ethylene-co-glycidyl methacrylate)

    SciTech Connect

    Warangkhana, Phromma; Rathanawan, Magaraphan; Jana Sadhan, C.

    2015-05-22

    The ternary blends of poly(lactic acid) (PLA), poly(ethylene-co-vinyl alcohol) (EVOH), and poly(ethylene-co-glycidyl methacrylate) (EGMA) were prepared. The role of EGMA as a compatibilizer was evaluated. The weight ratio of PLA:EVOH was 80:20 and the EGMA loadings were varied from 5-20 phr. The blends were characterized as follows: thermal properties by differential scanning calorimetry, morphology by scanning electron microscopy, and mechanical properties by pendulum impact tester, and universal testing machine. The glass transition temperature of PLA blends did not change much when compared with that of PLA. The blends of PLA/EGMA and EVOH/EGMA showed EGMA dispersed droplets where the latter led to poor impact properties. However, the tensile elongation at break and tensile toughness substantially increased upon addition of EGMA to blends of PLA and EVOH. It was noted in tensile test samples that both PLA and EVOH domains fibrillated significantly to produce toughness.

  4. Preparation and characterization of reactive blends of poly(lactic acid), poly(ethylene-co-vinyl alcohol), and poly(ethylene-co-glycidyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Warangkhana, Phromma; Jana Sadhan, C.; Rathanawan, Magaraphan

    2015-05-01

    The ternary blends of poly(lactic acid) (PLA), poly(ethylene-co-vinyl alcohol) (EVOH), and poly(ethylene-co-glycidyl methacrylate) (EGMA) were prepared. The role of EGMA as a compatibilizer was evaluated. The weight ratio of PLA:EVOH was 80:20 and the EGMA loadings were varied from 5-20 phr. The blends were characterized as follows: thermal properties by differential scanning calorimetry, morphology by scanning electron microscopy, and mechanical properties by pendulum impact tester, and universal testing machine. The glass transition temperature of PLA blends did not change much when compared with that of PLA. The blends of PLA/EGMA and EVOH/EGMA showed EGMA dispersed droplets where the latter led to poor impact properties. However, the tensile elongation at break and tensile toughness substantially increased upon addition of EGMA to blends of PLA and EVOH. It was noted in tensile test samples that both PLA and EVOH domains fibrillated significantly to produce toughness.

  5. Sophorolipid-derived unsaturated and epoxy fatty acid estolides as plasticizers for poly(3-hydroxybutyrate)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Unsaturated and epoxy fatty acid estolides were synthesized from the omega and omega-1 hydroxy fatty acids derived from sophorolipids (SLs) prepared by fermentation from glucose:soybean oil and glucose:oleic acid, respectively. These estolides were utilized as additives in solution-cast poly(3-hydro...

  6. Effect of peroxide and chain extender on mechanical properties and morphology of poly (butylene succinate)/poly (lactic acid) blends

    NASA Astrophysics Data System (ADS)

    Cherykhunthod, W.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    Poly (butylene succinate) (PBS) and poly (lactic acid) (PLA) are biodegradable polymers with high potential to replace commodity fossil-based polymers in a wide range of applications. However, these two polymers are immiscible in most ratios, but partially miscible when one of the two is a major phase. In this study, a one-step process in a twin-screw extruder was used to prepare the blends between poly (butylene succinate) (PBS) as a matrix and poly (lactic acid) (PLA) as a dispersed phase. To improve mechanical properties and morphology of blends, two reactive agents, peroxide (Perkadox) and multifunctional epoxide chain extender (Joncryl) were selected and compared. All samples were characterized for melt flow index (MFI), morphology, tensile, and impact properties. The results showed that the mechanical properties and morphology of PBS/PLA blends were improved when using both reactive agents. It was demonstrated that the increased mechanical properties resulted from good interfacial adhesion between PBS and finely dispersed PLA particles. The addition of 0.075 phr Perkadox to PBS/PLA (75:25 and 80:20) blends increased elongation at break by 7.2% and 38.4%, respectively compared with the blends without reactive agents. The results from gel content also revealed the graft copolymer existed at the interface when reactive agents were added. In the case of using multifunctional epoxide chain extender, the impact strength of the blends increased.

  7. Hemocompatibility of Chitosan/poly(acrylic acid) Grafted Polyurethane Tubing

    PubMed Central

    Lee, Hyun-Su; Tomczyk, Nancy; Kandel, Judith; Composto, Russell J.; Eckmann, David M.

    2013-01-01

    The activation and adhesion of platelets or whole blood exposed to chitosan (CH) grafted surfaces is used to evaluate the hemocompatibility of biomaterials. The biomaterial surfaces are polyurethane (PU) tubes grafted with an inner poly(acrylic acid) (PAA) and an outer CH or quaternary ammonium modified CH (CH-Q) brush. The CH, CH-Q and PAA grafted layers were characterized by ellipsometry and fluorescence microscopy. Material wear tests demonstrate that CH (CH-Q) is stably grafted onto PU tubes upon exposure to saline solution for 7 days. Using quartz-crystal microbalances with dissipation (QCM-D), in-situ adsorption of blood plasma proteins on CH and CH-Q compared to a silicon oxide control was measured. The QCM-D results showed that the physically adsorbed plasma protein layer on CH-Q and CH surfaces is softer and more viscous than the protein layer on the SiO2 surface. The CH-Q layer thus has the weakest interaction with plasma proteins. Whole blood and platelet adhesion was reduced by ~92% on CH-Q, which showed the weakest interaction with plasma protein but more viscous adsorbed plasma protein layer, compared to SiO2. Last, to examine the biologic response of platelets and neutrophils to biomaterial surfaces, CH (CH-Q)/PAA, PAA and PU tubes were tested using a Chandler Loop apparatus as an ex vivo model and flow cytometry. The blood adhesion and biologic response results showed that CH and CH-Q reduced adhesion and activation of platelets and neutrophils and improved hemocompatibility relative to other surfaces (PU and PAA). Our studies demonstrated that the properties of physically adsorbed plasma protein layer on biomaterial surfaces correlates with blood coagulation on biomaterial surfaces. PMID:24349719

  8. Hemocompatibility of Chitosan/poly(acrylic acid) Grafted Polyurethane Tubing.

    PubMed

    Lee, Hyun-Su; Tomczyk, Nancy; Kandel, Judith; Composto, Russell J; Eckmann, David M

    2013-12-14

    The activation and adhesion of platelets or whole blood exposed to chitosan (CH) grafted surfaces is used to evaluate the hemocompatibility of biomaterials. The biomaterial surfaces are polyurethane (PU) tubes grafted with an inner poly(acrylic acid) (PAA) and an outer CH or quaternary ammonium modified CH (CH-Q) brush. The CH, CH-Q and PAA grafted layers were characterized by ellipsometry and fluorescence microscopy. Material wear tests demonstrate that CH (CH-Q) is stably grafted onto PU tubes upon exposure to saline solution for 7 days. Using quartz-crystal microbalances with dissipation (QCM-D), in-situ adsorption of blood plasma proteins on CH and CH-Q compared to a silicon oxide control was measured. The QCM-D results showed that the physically adsorbed plasma protein layer on CH-Q and CH surfaces is softer and more viscous than the protein layer on the SiO2 surface. The CH-Q layer thus has the weakest interaction with plasma proteins. Whole blood and platelet adhesion was reduced by ~92% on CH-Q, which showed the weakest interaction with plasma protein but more viscous adsorbed plasma protein layer, compared to SiO2. Last, to examine the biologic response of platelets and neutrophils to biomaterial surfaces, CH (CH-Q)/PAA, PAA and PU tubes were tested using a Chandler Loop apparatus as an ex vivo model and flow cytometry. The blood adhesion and biologic response results showed that CH and CH-Q reduced adhesion and activation of platelets and neutrophils and improved hemocompatibility relative to other surfaces (PU and PAA). Our studies demonstrated that the properties of physically adsorbed plasma protein layer on biomaterial surfaces correlates with blood coagulation on biomaterial surfaces. PMID:24349719

  9. Protonated polynucleotides structures - 23. The acid-base hysteresis of poly(dG).poly(dC).

    PubMed Central

    Thiele, D; Marck, C; Schneider, C; Guschlbauer, W

    1978-01-01

    The large hysteresis observed during the acid-base titration of poly(dG). poly (dC) was studied by CD and potentiometric scanning curves. Intermediate scanning loops as well as the equilibrium and metastable branches of the hysteresis loop have been determined. The potentiometric titrations showed, however, that the various complexes were not discrete entities, but were linked in "polycomplexes" as had been already suggested. This prevented a thermodynamic study of the system. The acid-base titration was further investigated as a function of ionic strength and temperature. The pK's showed considerably lower ionic strength dependence than observed for polyribonucleotide complexes. The thermal transitions permitted to establish the relative stabilities of the various complexes between pH 2.5 and pH 12.0. PMID:27762

  10. Inherently antioxidant and antimicrobial tannic acid release from poly(tannic acid) nanoparticles with controllable degradability.

    PubMed

    Sahiner, Nurettin; Sagbas, Selin; Aktas, Nahit; Silan, Coskun

    2016-06-01

    From a natural polyphenol, Tannic acid (TA), poly(TA) nanoparticles were readily prepared using a single step approach with three different biocompatible crosslinkers; trimethylolpropane triglycidyl ether (TMPGDE), poly(ethylene glycol) diglycidyl ether (PEGGE), and trisodium trimetaphosphate (STMP). P(TA) particles were obtained with controllable diameters between 400 to 800nm with -25mV surface charge. The effect of synthesis conditions, such as the emulsion medium, pH values of TA solution, and the type of crosslinker, on the shape, size, dispersity, yield, and degradability of poly(Tannic Acid) (p(TA)) nanoparticles was systematically investigated. The hydrolytic degradation amount in physiological pH conditions of 5.4, 7.4, and 9.0 at 37.5°C were found to be in the order TMPGDE

  11. Poly(carbonate–amide)s Derived from Bio-Based Resources: Poly(ferulic acid-co-tyrosine)

    PubMed Central

    2015-01-01

    Ferulic acid (FA), a bio-based resource found in fruits and vegetables, was coupled with a hydroxyl-amino acid to generate a new class of monomers to afford poly(carbonate–amide)s with potential to degrade into natural products. l-Serine was first selected as the hydroxyl-amino partner for FA, from which the activated p-nitrophenyl carbonate monomer was synthesized. Unfortunately, polymerizations were unsuccessful, and the elimination product was systematically obtained. To avoid elimination, we revised our strategy and used l-tyrosine ethyl ester, which lacks an acidic proton on the α position of the ethyl ester. Four new monomers were synthesized and converted into the corresponding poly(carbonate–amide)s with specific regioselectivities. The polymers were fully characterized through thermal and spectroscopic analyses. Preliminary fluorescent studies revealed interesting photophysical properties for the monomers and their corresponding poly(carbonate–amide)s, beyond the fluorescence characteristics of l-tyrosine and FA, making these materials potentially viable for sensing and/or imaging applications, in addition to their attractiveness as engineering materials derived from renewable resources. PMID:24839309

  12. Methyl-branched poly(hydroxyalkanoate) biosynthesis from 13- methyltetradecanoic acid and mixed isostearic acid isomer substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas resinovorans, a known medium-chain-length (mcl-) poly(hydroxyalkanoate) (PHA) producer, was grown on 13-methyltetradecanoic acid (13-MTDA) and a mixture of isostearic acid (IA) isomers to produce methyl-branched mcl-PHA polymers. Shake flask experiments revealed polymer productivities (...

  13. Optimization of a biomimetic poly-(lactic acid) ligament scaffold

    NASA Astrophysics Data System (ADS)

    Uehlin, Andrew F.

    The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was used to create nanofibers of PLA, followed by an induced degradation of the nanofibers via 0.25M NaOH hydrolysis. The effects of the unidirectional electrospinning as well as the effects of NaOH hydrolysis on fiber alignment, fiber diameter, surface morphology, crystallinity, in vitro swelling, immobilization of fibrin, and mechanical properties were investigated, resulting in a modified morphology correlating to the microstructure of native ligament tissue with similar mechanical properties. Furthering the development of the PLA nanomatrix composite, a bioinkjet printer was used to immobilize nanoparticulate hydroxyapatite (HANP) on the surface of the scaffold. A series of 300pL droplets of HANP bioink were printed over a gradient pattern mimetic of (and spatially corresponding to) the mineralization gradient found over the microanatomy at the ACL enthesis. Proliferation and differentiation response of human mesenchymal stem cells (hMSCs) in vitro was assessed on a variety of conditions and combinations of the PLA nanofiber scaffold surface modifications (inclusive and exclusive of HANP, fibrin, and various time dependent NaOH treatments). It was found that a combinatory effect of the HANP gradient with fibrin on 20 minute NaOH treated PLA

  14. Simultaneous and selective production of levan and poly(gamma-glutamic acid) by Bacillus subtilis.

    PubMed

    Shih, Ing-Lung; Yu, Yun-Ti

    2005-01-01

    Bacillus subtilis(natto) Takahashi, used to prepare the fermented soybean product natto, was grown in a basal medium containing 5% (w/w) sucrose and 1.5% (w/w) L-glutamate and produced 58% (w/w) poly(gamma-glutamic acid) and 42% (w/w) levan simultaneously. After 21 h, 40-50 mg levan ml-1 had been produced in medium containing 20% (w/w) sucrose but without L-glutamate. In medium containing L-glutamic acid but without sucrose, mainly poly(gamma-glutamic acid) was produced. PMID:15703872

  15. Physicochemical Properties and Applications of Poly(lactic-co-glycolic acid) for Use in Bone Regeneration

    PubMed Central

    Félix Lanao, Rosa P.; Jonker, Anika M.; Wolke, Joop G.C.; Jansen, John A.; van Hest, Jan C.M.

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) is the most often used synthetic polymer within the field of bone regeneration owing to its biocompatibility and biodegradability. As a consequence, a large number of medical devices comprising PLGA have been approved for clinical use in humans by the American Food and Drug Administration. As compared with the homopolymers of lactic acid poly(lactic acid) and poly(glycolic acid), the co-polymer PLGA is much more versatile with regard to the control over degradation rate. As a material for bone regeneration, the use of PLGA has been extensively studied for application and is included as either scaffolds, coatings, fibers, or micro- and nanospheres to meet various clinical requirements. PMID:23350707

  16. A multivariant study of the absorption properties of poly(glutaric-acid-glycerol) films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The solvent absorption into the matrix of poly(glutaric acid-glycerol) films made with or without either iminodiacetic acid, sugarcane bagasse, pectin, corn fiber gum or microcrystalline cellulose have been evaluated. The films were incubated in various solvent systems for 24h. The amounts of solve...

  17. Utilizing acid pretreatment and electrospinning to improve biocompatibility of poly(glycolic acid) for tissue engineering.

    PubMed

    Boland, Eugene D; Telemeco, Todd A; Simpson, David G; Wnek, Gary E; Bowlin, Gary L

    2004-10-15

    Poly(glycolic acid) (PGA) has a long history as a bioresorbable polymer. Its biocompatibility is widely accepted, yet PGA is often rejected as a soft-tissue scaffold because of fibrous encapsulation. The goal of this study was to improve the soft-tissue biocompatibility of PGA by producing scaffolds composed of small-diameter fibers through electrospinning and subjecting these scaffolds to a concentrated hydrochloric acid (HCL) pretreatment. The theory is that small-diameter fibers will elicit a reduced immune response and HCl treatment will improve cellular interactions. Scaffolds were characterized in terms of fiber diameter and pore area via image-analysis software. Biocompatibility was assessed through a WST-1 cell-proliferation assay (in vitro) with the use of rat cardiac fibroblasts and rat intramuscular implantations (in vivo). Fibers produced ranged in diameter from 0.22 to 0.88 microm with pore areas from 1.84 to 13.22 microm(2). The untreated scaffold composed of 0.88-microm fibers was encapsulated in vivo and supported the lowest rates of cell proliferation. On the contrary, the acid pretreated scaffold with 0.22-microm fibers was incorporated into the surrounding tissue and exhibited proliferation rates that exceeded the control populations on tissue-culture plastic. In conclusion, this study has shown the ability to improve the biocompatibility of PGA through acid pretreatment of scaffolds comprised of submicron fiber diameters. PMID:15368238

  18. Synthesis and characterization of β-napthalene sulphonic acid doped poly(o-anisidine)

    NASA Astrophysics Data System (ADS)

    Sangamithirai, D.; Narayanan, V.; Stephen, A.

    2014-04-01

    Poly(o-anisidine) doped with β-napthalene sulphonic acid (β-NSA) was synthesized using ammonium persulphate as an oxidizing agent. The polymer was characterized by using FTIR, XRD and conductivity measurements. The FTIR spectra reveal the presence of functional groups that account for the formation of polymer. The structure was characterized by XRD. The conductivity of the poly(o-anisidine) salt was found to be 2.25 × 10-6 S/m.

  19. Miscibility of poly(lactic acid) and poly(ethylene oxide) solvent polymer blends and nanofibers made by solution blow spinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The miscibility of blends of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) was studied in polymer solutions by dilute solution viscometry and in solution blow spun nanofibers by microscopy (SEM, TEM) and by thermal and spectral analysis. Three blends of PLA and PEO were solution blended in...

  20. Complex Formation Between Lysozyme and Stabilized Micelles with a Mixed Poly(ethylene oxide)/Poly(acrylic acid) Shell.

    PubMed

    Karayianni, Maria; Gancheva, Valeria; Pispas, Stergios; Petrov, Petar

    2016-03-10

    The electrostatic complexation between lysozyme and stabilized polymeric micelles (SPMs) with a poly(acrylic acid) (PAA) or a mixed poly(ethylene oxide)/poly(acrylic acid) (PEO/PAA) shell (SPMs with a mixed shell, SPMMS) and a temperature-responsive poly(propylene oxide) (PPO) core was investigated by means of dynamic, static, and electrophoretic light scattering. The SPMs and different types of SPMMS used resulted from the self-assembly of PAA-PPO-PAA triblock copolymer chains, or PAA-PPO-PAA and PEO-PPO-PEO triblock copolymer chain mixtures (with varying chain lengths and molar ratios) in aqueous solutions at pH 10 and the subsequent cross-linking of their PPO cores via loading and photo-cross-linking of pentaerythritol tetraacrylate (PETA). The solution behavior, structure and properties of the formed complexes at pH 7 and 0.01 M ionic strength, were studied as a function of the protein concentration in the solution (the concentration of the stabilized micelles was kept constant) or equivalently the ratio of the two components. The complexation process and properties of the complexes proved to be dependent on the protein concentration, while of particular interest was the effect of the structure of the shell of the SPMs on the stability/solubility of the complexes. Finally, the fluorescence and mid infrared spectroscopic investigation of the structure of the complexed protein showed that, although a small stretching of the protein molecules occurred in some cases, no protein denaturation takes place upon complexation. PMID:26881445

  1. Effect of an acid filler on hydrolysis and biodegradation of poly-lactic acid (PLA)

    NASA Astrophysics Data System (ADS)

    Iozzino, Valentina; Speranza, Vito; Pantani, Roberto

    2015-12-01

    The use of biodegradable polymers is certainly an excellent strategy to solve many of the problems related to the disposal of the traditional polymers, whose accumulation in the environment is harmful and damaging. In order to optimize the use of biodegradable polymers, it is very important to understand and control the transformation processes, the structures and the morphologies resulting from the process conditions used to produce the articles and, not least, the biodegradation. The latter is strictly dependent on the just mentioned variables. The poly-lactic acid, PLA, is a biodegradable polymer. Many studies have been carried out on the degradation process of this polymer. In the course of this work we performed degradation tests on the PLA, with a specific D-isomer content, having amorphous structure, and in particular of biodegradation and hydrolysis. An acid chemical, fumaric acid, was added to PLA with the objective of controlling the rate of hydrolysis and of biodegradation. The hydrolysis process was followed, as function of time, by means of different techniques: pH variation, variation of weight of samples and variation of crystallinity degree and glass transition temperature using DSC analysis. The samples were also analyzed in terms of biodegradability by means of a homemade respirometer apparatus, in controlled composting conditions.

  2. Biological and Tribological Assessment of Poly(Ethylene Oxide Terephthalate)/Poly(Butylene Terephthalate), Polycaprolactone, and Poly (L\\DL) Lactic Acid Plotted Scaffolds for Skeletal Tissue Regeneration.

    PubMed

    Hendrikson, Wilhelmus J; Zeng, Xiangqiong; Rouwkema, Jeroen; van Blitterswijk, Clemens A; van der Heide, Emile; Moroni, Lorenzo

    2016-01-21

    Additive manufactured scaffolds are fabricated from three commonly used biomaterials, polycaprolactone (PCL), poly (L\\DL) lactic acid (P(L\\DL)LA), and poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT). Scaffolds are compared biologically and tribologically. Cell-seeded PEOT/PBT scaffolds cultured in osteogenic and chondrogenic differentiation media show statistical significantly higher alkaline phosphatase (ALP) activity/DNA and glycosaminoglycans (GAG)/DNA ratios, followed by PCL and P(L\\DL)LA scaffolds, respectively. The tribological performance is assessed by determining the friction coefficients of the scaffolds at different loads and sliding velocities. With increasing load or decreasing sliding velocity, the friction coefficient value decreases. PEOT/PBT show to have the lowest friction coefficient value, followed by PCL and P(L\\DL)LA. The influence of the scaffold architecture is further determined with PEOT/PBT. Reducing of the fiber spacing results in a lower friction coefficient value. The best and the worst performing scaffold architecture are chosen to investigate the effect of cell culture on the friction coefficient. Matrix deposition is low in the cell-seeded scaffolds and the effect is, therefore, undetermined. Taken together, our studies show that PEOT/PBT scaffolds support better skeletal differentiation of seeded stromal cells and lower friction coefficient compared to PCL and P(L/DL)A scaffolds. PMID:26775915

  3. Systematic unravelling of the biosynthesis of poly (L-diaminopropionic acid) in Streptomyces albulus PD-1.

    PubMed

    Xu, Zhaoxian; Sun, Zhuzhen; Li, Sha; Xu, Zheng; Cao, Changhong; Xu, Zongqi; Feng, Xiaohai; Xu, Hong

    2015-01-01

    Poly(L-diaminopropionic acid) (PDAP) is one of the four homopoly(amino acid)s that have been discovered in nature. However, the molecular mechanism of PDAP biosynthesis has yet to be described. In this work, the general layout of the PDAP biosynthetic pathway is characterised in Streptomyces albulus PD-1 by genome mining, gene disruption, heterologous expression and in vitro feeding experiments. As a result, L-diaminopropionic acid (L-DAP), which is the monomer of PDAP, is shown to be jointly synthesised by two protein homologues of cysteine synthetase and ornithine cyclodeaminase. Then, L-DAP is assembled into PDAP by a novel nonribosomal peptide synthetase (NRPS) with classical adenylation and peptidyl carrier protein domains. However, instead of the traditional condensation or thioesterase domain of NRPSs, this NRPS has seven transmembrane domains surrounding three tandem soluble domains at the C-terminus. As far as we know, this novel single-module NRPS structure has only been reported in poly(ε-L-lysine) synthetase. The similar NRPS structure of PDAP synthetase and poly(ε-L-lysine) synthetase may be a common characteristic of homopoly(amino acid)s synthetases. In this case, we may discover and/or design more homopoly(amino acid)s by mining this kind of novel NRPS structure in the future. PMID:26632244

  4. Systematic unravelling of the biosynthesis of poly (L-diaminopropionic acid) in Streptomyces albulus PD-1

    PubMed Central

    Xu, Zhaoxian; Sun, Zhuzhen; Li, Sha; Xu, Zheng; Cao, Changhong; Xu, Zongqi; Feng, Xiaohai; Xu, Hong

    2015-01-01

    Poly(L-diaminopropionic acid) (PDAP) is one of the four homopoly(amino acid)s that have been discovered in nature. However, the molecular mechanism of PDAP biosynthesis has yet to be described. In this work, the general layout of the PDAP biosynthetic pathway is characterised in Streptomyces albulus PD-1 by genome mining, gene disruption, heterologous expression and in vitro feeding experiments. As a result, L-diaminopropionic acid (L-DAP), which is the monomer of PDAP, is shown to be jointly synthesised by two protein homologues of cysteine synthetase and ornithine cyclodeaminase. Then, L-DAP is assembled into PDAP by a novel nonribosomal peptide synthetase (NRPS) with classical adenylation and peptidyl carrier protein domains. However, instead of the traditional condensation or thioesterase domain of NRPSs, this NRPS has seven transmembrane domains surrounding three tandem soluble domains at the C-terminus. As far as we know, this novel single-module NRPS structure has only been reported in poly(ε-L-lysine) synthetase. The similar NRPS structure of PDAP synthetase and poly(ε-L-lysine) synthetase may be a common characteristic of homopoly(amino acid)s synthetases. In this case, we may discover and/or design more homopoly(amino acid)s by mining this kind of novel NRPS structure in the future. PMID:26632244

  5. Rapid Trimming of Cell Surface Polysialic Acid (PolySia) by Exovesicular Sialidase Triggers Release of Preexisting Surface Neurotrophin.

    PubMed

    Sumida, Mizuki; Hane, Masaya; Yabe, Uichiro; Shimoda, Yasushi; Pearce, Oliver M T; Kiso, Makoto; Miyagi, Taeko; Sawada, Makoto; Varki, Ajit; Kitajima, Ken; Sato, Chihiro

    2015-05-22

    As acidic glycocalyx on primary mouse microglial cells and a mouse microglial cell line Ra2, expression of polysialic acid (polySia/PSA), a polymer of the sialic acid Neu5Ac (N-acetylneuraminic acid), was demonstrated. PolySia is known to modulate cell adhesion, migration, and localization of neurotrophins mainly on neural cells. PolySia on Ra2 cells disappeared very rapidly after an inflammatory stimulus. Results of knockdown and inhibitor studies indicated that rapid surface clearance of polySia was achieved by secretion of endogenous sialidase Neu1 as an exovesicular component. Neu1-mediated polySia turnover was accompanied by the release of brain-derived neurotrophic factor normally retained by polySia molecules. Introduction of a single oxygen atom change into polySia by exogenous feeding of the non-neural sialic acid Neu5Gc (N-glycolylneuraminic acid) caused resistance to Neu1-induced polySia turnover and also inhibited the associated release of brain-derived neurotrophic factor. These results indicate the importance of rapid turnover of the polySia glycocalyx by exovesicular sialidases in neurotrophin regulation. PMID:25750127

  6. Poly(amidoamine) dendrimer-enabled simultaneous stabilization and functionalization of electrospun poly(γ-glutamic acid) nanofibers.

    PubMed

    Wang, Shige; Zhu, Jingyi; Shen, Mingwu; Zhu, Meifang; Shi, Xiangyang

    2014-02-12

    We report a facile and general approach to using generation 2 (G2) poly(amidoamine) (PAMAM) dendrimers for simultaneous stabilization and functionalization of electrospun poly(γ-glutamic acid) nanofibers (γ-PGA NFs). In this study, uniform γ-PGA NFs with a smooth morphology were generated using electrospinning technology. In order to endow the NFs with good water stability, amine-terminated G2.NH2 PAMAM dendrimers were utilized to crosslink the γ-PGA NFs via 1-ethyl-3-(3-dimethylami-nopropyl) carbodiimide coupling chemistry. Under the optimized crosslinking conditions, G2.NH2 dendrimers partially modified with fluorescein isothiocyanate (FI) or folic acid (FA) were used to crosslink γ-PGA NFs. Our results reveal that G2.NH2-FI is able to simultaneously render the NFs with good water stability and fluorescence property, while G2.NH2-FA is able to simultaneously endow the NFs with water stability and the ability to capture FA receptor-overexpressing cancer cells in vitro via ligand-receptor interaction. With the tunable dendrimer surface chemistry, multifunctional water-stable γ-PGA-based NFs may be generated via a dendrimer crosslinking approach, thereby providing diverse applications in the areas of biosensing, tissue engineering, drug delivery, and environmental sciences. PMID:24456208

  7. Synthesis and characterisation of a degradable poly(lactic acid)-poly(ethylene glycol) copolymer with biotinylated end groups.

    PubMed

    Salem, A K; Cannizzaro, S M; Davies, M C; Tendler, S J; Roberts, C J; Williams, P M; Shakesheff, K M

    2001-01-01

    Poly(lactic acid)-poly(ethylene glycol)-biotin (PLA-PEG-biotin) is a degradable polymer with protein resistant properties that can undergo rapid surface engineering in aqueous media to create biomimetic surfaces. Surface engineering of this polymer is dependent on biomolecular interactions between the biotin end group and the protein avidin. Given the vigorous conditions of synthesis, it is essential that the manufacture of the polymer does not alter the biotin structure or its molecular recognition. Equally, it is important that the incorporation of biotin does not adversely affect the physicochemical properties of the polymer. (1)H NMR provides evidence of biotin attachment and structural integrity. (1)H NMR, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) analysis shows there is no significant effect on bulk properties induced by the biotin end group. Surface plasmon resonance (SPR) and fluorescent spectroscopy studies using the 2-(4'-hydroxyazobenzene) benzoic acid (HABA)/avidin complex show that the biotin moieties binding capabilities are not impaired by the synthesis. PMID:11749223

  8. Synthesis and characterization of hydrolysed starch-g-poly(methacrylic acid) composite.

    PubMed

    Zahran, Magdy K; Ahmed, Enas M; El-Rafie, Mohamed H

    2016-06-01

    A novel method for the synthesis of starch-g-poly(methacrylic acid) composite was adopted by graft polymerization of hydrolysed starch (HS) and methacrylic acid (MAA) in aqueous medium using an efficient sodium perborate (SPB)-thiourea (TU) redox initiation system. The parameters influencing the redox system efficiency and thence the polymerization method were considered. These parameters comprehended the concentrations of MAA, SPB, TU and SPB/TU molar ratio as well as the polymerization temperature. The polymerization reaction was scrutinized through calculation of the MAA total conversion percent (TC%). The resultant poly(MAA-HS) composite was assessed by evaluating the polymer criteria (the graft yield, GY%; the grafting efficiency, GE%; the homopolymer, HP%; and the total conversion). The comportment of the apparent viscosity of the cooked poly(MAA)-starch composite paste, obtained under diverse polymerization conditions, was examined. Tentative mechanisms, which depict all occasions that happen amid the entire course of the polymerization reaction, have been proffered. PMID:26968925

  9. Determination of dopamine in presence of ascorbic acid and uric acid using poly (Spands Reagent) modified carbon paste electrode.

    PubMed

    Veera Manohara Reddy, Y; Prabhakara Rao, V; Vijaya Bhaskar Reddy, A; Lavanya, M; Venu, M; Lavanya, M; Madhavi, G

    2015-12-01

    In this paper, we have fabricated a modified carbon paste electrode (CPE) by electropolymerisation of spands reagent (SR) onto surface of CPE using cyclic voltammetry (CV). The developed electrode was abbreviated as poly(SR)/CPE and the surface morphology of the modified electrode was studied by using scanning electron microscopy (SEM). The developed electrode showed higher electrocatalytic properties towards the detection of dopamine (DA) in 0.1M phosphate buffer solution (PBS) at pH7.0. The effect of pH, scan rate, accumulation time and concentration of dopamine was studied at poly(SR)/CPE. The poly(SR)/CPE was successfully used as a sensor for the selective determination of DA in presence of ascorbic acid (AA) and uric acid (UA) without any interference. The poly(SR)/CPE showed a good detection limit of 0.7 μM over the linear dynamic range of 1.6 μM to 16 μM, which is extremely lower than the reported methods. The prepared poly(SR)/CPE exhibited good stability, high sensitivity, better reproducibility, low detection limit towards the determination of DA. The developed method was also applied for the determination of DA in real samples. PMID:26354279

  10. Antioxidant poly(lactic-co-glycolic) acid nanoparticles made with α-tocopherol-ascorbic acid surfactant.

    PubMed

    Astete, Carlos E; Dolliver, Debra; Whaley, Meocha; Khachatryan, Lavrent; Sabliov, Cristina M

    2011-12-27

    The goal of the study was to synthesize a surfactant made of α-tocopherol (vitamin E) and ascorbic acid (vitamin C) of antioxidant properties dubbed as EC, and to use this surfactant to make poly(lactic-co-glycolic) acid (PLGA) nanoparticles. Self-assembled EC nanostructures and PLGA-EC nanoparticles were made by nanoprecipitation, and their physical properties (size, size distribution, morphology) were studied at different salt concentrations, surfactant concentrations, and polymer/surfactant ratios. EC surfactant was shown to form self-assembled nanostructures in water with a size of 22 to 138 nm in the presence of sodium chloride, or 12 to 31 nm when synthesis was carried out in sodium bicarbonate. Polymeric PLGA-EC nanoparticles presented a size of 90 to 126 nm for 40% to 120% mass ratio PLGA to surfactant. For the same mass ratios, the PLGA-Span80 formed particles measured 155 to 216 nm. Span80 formed bilayers, whereas EC formed monolayers at the interfaces. PLGA-EC nanoparticles and EC showed antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay measurements using UV and EPR techniques, antioxidant activity which is not characteristic to commercially available Span80. The thiobarbituric acid reactive substances (TBARS) assay for lipid peroxidation showed that PLGA nanoparticles with EC performed better as antioxidants than the EC nanoassembly or the free vitamin C. Nanoparticles were readily internalized by HepG2 cells and were localized in the cytoplasm. The newly synthesized EC surfactant was therefore found successful in forming uniform, small size polymeric nanoparticles of intrinsic antioxidant properties. PMID:22017172

  11. Cationic poly(lactic-co-glycolic acid) iron oxide microspheres for nucleic acid detection

    NASA Astrophysics Data System (ADS)

    Pandey, Chandra Mouli; Sharma, Aditya; Sumana, Gajjala; Tiwari, Ida; Malhotra, Bansi Dhar

    2013-04-01

    Herein, we envisage the possibility of preparing stable cationic poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulating the iron oxide nanoparticles (IONPs; 8-12 nm). The IONPs are incorporated into PLGA in organic phase followed by microsphere formation and chitosan coating in aqueous medium via nano-emulsion technique. The average size of the microspheres, as determined by dynamic light scattering are about 310 nm, while the zeta potential for the composite remains near 35 mV at pH 4.0. These microspheres are electrophoretically deposited onto indium tin oxide (ITO)-coated glass substrate used as cathode and parallel platinum plate as the counter electrode. This platform is utilized to fabricate a DNA biosensor, by immobilizing a probe sequence specific to Escherichia coli. The bioelectrode shows a surface-controlled electrode reaction with the electron transfer coefficient (α) of 0.64 and charge transfer rate constant (ks) of 61.73 s-1. Under the optimal conditions, this biosensor shows a detection limit of 8.7 × 10-14 M and is found to retain about 81% of the initial activity after 9 cycles of use.Herein, we envisage the possibility of preparing stable cationic poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulating the iron oxide nanoparticles (IONPs; 8-12 nm). The IONPs are incorporated into PLGA in organic phase followed by microsphere formation and chitosan coating in aqueous medium via nano-emulsion technique. The average size of the microspheres, as determined by dynamic light scattering are about 310 nm, while the zeta potential for the composite remains near 35 mV at pH 4.0. These microspheres are electrophoretically deposited onto indium tin oxide (ITO)-coated glass substrate used as cathode and parallel platinum plate as the counter electrode. This platform is utilized to fabricate a DNA biosensor, by immobilizing a probe sequence specific to Escherichia coli. The bioelectrode shows a surface-controlled electrode reaction with the

  12. NMR analysis and tacticity determination of poly(lactic acid) in C5D5N

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work tacticity assignments of poly(lactic acid), (PLA), are reported for the NMR peaks from CH carbon and CH3 proton at the tetrad level in deuterated pyridine. The methyl protons are better resolved in pyridine due to solvent effects such as ring current shielding of the aromatic ring and ...

  13. POLY(LACTIC ACID) GREEN COMPOSITES USING OILSEED COPRODUCTS AS FILLERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid), PLA, is a biodegradable polymer made from renewable resources with similar mechanical properties to polypropylene. PLA is more expensive than petroleum-based plastics, and the use of low-cost fillers as extenders is desirable. Agricultural co-products of the alternative oilseed ...

  14. GREEN COMPOSITES OF POLY(LACTIC ACID) AND OILSEED CO-PRODUCTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid)(PLA) is a biodegradable plastic made from renewable resources and has similar mechanical properties to polypropylene. PLA is more expensive than petroleum-based plastics, and the use of low-cost fillers as extenders is desirable. Agricultural co-products (AcP) of oilseed crops we...

  15. Low-Melt Poly(amic Acids) and Polyimides and Their Uses

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor); Parrish, Clyde F. (Inventor); Parks, Steven L. (Inventor)

    2015-01-01

    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use in repair of electrical wire insulation, flat or ribbon wire harnesses, and flat surfaces comprised of high-performance polymers such as inflatables or solar panels applications. Also provided are methods and devices for repair of electrical insulation.

  16. Low-Melt Poly(Amic Acids) and Polyimides and Their Uses

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor); Parrish, Clyde F. (Inventor); Parks, Steven L. (Inventor)

    2014-01-01

    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use in repair of electrical wire insulation, flat or ribbon wire harnesses, and flat surfaces comprised of high-performance polymers such as inflatables or solar panels applications. Also provided are methods and devices for repair of electrical insulation.

  17. EVALUATION OF POLY(LACTIC ACID) AND AGRICULTURAL COPRODUCTS AS GREEN COMPOSITE MATERIALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Green composite materials of poly(lactic acid)(PLA) and agricultural coproducts such as sugar beet pulp(SBP), cuphea, lesquerella, and milkweed were compounded using a twin-screw extruder, molded by injection molding and evaluated for structural and mechanical properties using acoustic emission and ...

  18. THERMAL PROPERTIES OF EXTRUDED-INJECTION MOLDED POLY (LACTIC ACID) AND MILKWEED COMPOSITES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (Lactic Acid...

  19. Starch/fiber/poly(lactic acid) foam and compressed foam composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were compressed into plastics using force ranging from 4-76MPa. Te...

  20. PREPARATION AND CHARACTERIZATION OF POLY (LACTIC ACID) GREEN COMPOSITES USING AGRICULTURAL CO-PRODUCTS AS FILLERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly (lactic acid) is a biodegradable plastic made from renewable resources and has similar mechanical properties to polypropylene. PLA is more expensive than petroleum-based plastics, and the use of low-cost fillers as extenders is desirable. Agricultural co-products (AcP) of oilseed crops were c...

  1. Preparation of poly(lactic acid) and pectin composite films intended for application in antimicrobial packaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composite films of pectin and poly(lactic acid) (PLA) were compounded by extrusion. A model antimicrobial polypeptide, nisin, was loaded into the film by diffusion. The incorporation of pectin into PLA resulted in a heterogeneous biphasic structure as revealed by scanning electronic microscopy, co...

  2. Poly(beta-L-malic acid) from agricultural substrates by Aureobasidium pullulans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report here for the first time the production of poly(beta-L-malic acid) (PMA) from agricultural substrates by the yeastlike fungus Aureobasidium pullulans. PMA is a natural biopolyester that has primarily been studied for biomedical uses as a drug carrier. However, PMA also has potential as a ...

  3. Sugar beet pulp and poly(lactic acid) composites using methylene diphenyl diisocyanate as coupling agent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composites from sugar beet pulp (SBP) and poly(lactic acid) (PLA) were extruded in the presence of polymeric methylene diphenyl diisocyanate (pMDI). SBP particles were evenly distributed within the PLA matrix phase as revealed by confocal fluorescence microscopic analysis. The resultant composites w...

  4. Low-Melt Poly(Amic Acids) and Polyimides and Their Uses

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor); Parrish, Clyde F. (Inventor); Snyder, Sarah J. (Inventor)

    2016-01-01

    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use as adhesives, and methods of using the materials for attaching two substrates. The methods typically form an adhesive bond that is hermetically sealed to both substrates. Additionally, the method typically forms a cross-linked bonding material that is flexible.

  5. Poly (beta-L-malic acid) production by diverse phylogenetic clades of Aureobasidium pullulans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly (beta-L-malic acid) (PMA) is a natural biopolyester that has pharmaceutical applications and other potential uses. Here we examine PMA production by genetically diverse phylogenetic clades of the fungus A. pullulans. Thirty-six strains of A. pullulans were isolated for this study from various...

  6. Phospholipids and poly(glutamic acid)/hydrolyzed gluten: interaction and kinetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of poly (glutamic acid) (PGA) and Hydrolyzed wheat gluten (HG) on the thermal and kinetics properties of lysophosphatidylcholine (LPC) was determined using Differential Scanning Calorimetry (DSC). A model system containing 3, 6 and 10% PGA or HG was added to 40% LPC aqueous suspension. ...

  7. Solution blow spun Poly(lactic acid)/Hydroxypropyl methylcellulose nanofibers with antimicrobial properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) nanofibers containing hydroxypropyl methylcellulose (HPMC) and tetracycline hydrochloride (THC) were solution blow spun from two different solvents, chloroform/acetone (CA, 80:20 v/v) and 2,2,2-triflouroethanol (TFE). The diameter distribution, chemical, thermal, thermal stab...

  8. Production of poly(beta-L-malic acid) (PMA) from agricultural biomass substrates by Aureobasidium pullulans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report here for the first time the production of poly(beta-L-malic acid) (PMA) from agricultural biomass substrates by the yeastlike fungus Aureobasidium pullulans. Strains NRRL Y 2311-1, NRRL 50382, NRRL 50383, and NRRL 50384, representing diverse isolation sources and phylogenetic clades, prod...

  9. Synthesis and characterization of amylose grafted poly(acrylic acid) and its application in ammonia adsorption.

    PubMed

    Chen, Qing; Yu, Haojie; Wang, Li; Abdin, Zain-Ul; Yang, Xinpeng; Wang, Junhua; Zhou, Weidong; Zhang, Hongtao; Chen, Xiao

    2016-11-20

    Amylose grafted poly(acrylic acid) (Am-g-PAA) was synthesized by graft copolymerization of amylose with acrylic acid. The structure of Am-g-PAA was confirmed by (1)H NMR and FT-IR spectra. The morphology, crystallinity and thermal properties of amylose and Am-g-PAA were investigated by SEM, XRD and TGA, respectively. The highest degree of substitution (DS) of carboxyl group was 1.96 which was obtained after reacted for 1h at 60°C. Acrylic acid to anhydroglucose mole ratio for DS was 19.81. It was found that a large number of carboxyl groups were grafted on the backbone of amylose. It was also found that ammonia adsorption capacity of amylose increased by grafting poly(acrylic acid) on the backbone of amylose. PMID:27561514

  10. Electrospun homogeneous silk fibroin/poly (ɛ-caprolactone) nanofibrous scaffolds by addition of acetic acid for tissue engineering.

    PubMed

    Zhu, Jiang; Luo, Jingjing; Zhao, Xingyan; Gao, Junjiu; Xiong, Jie

    2016-09-01

    In this study, we investigated the phase separation phenomenon of silk fibroin/poly (ɛ-caprolactone) electrospinning solution to improve the performance of silk fibroin/poly (ɛ-caprolactone) electrospun nanofibers. It showed that phase separation does occur in just a few hours in the silk fibroin/poly (ɛ-caprolactone)/formic acid mixture solution. Acetic acid, small molecule nonsolvent for silk fibroin, was first introduced to silk fibroin/poly (ɛ-caprolactone)/formic acid solution, a homogeneous solution without separation for over several days was achieved after mixing for 5 h. The morphology and composition of the silk fibroin/poly (ɛ-caprolactone) and acetic acid-modified silk fibroin/poly (ɛ-caprolactone) fibrous scaffolds were examined by scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analyzer. Attachment and proliferation of mouse osteoblast MC3T3-E1 cells were tested by scanning electron microscopy and cytotoxity assay. The results indicated that the phase separation of silk fibroin/poly (ɛ-caprolactone) solution might led to inhomogeneous morphology and composition of the composite scaffolds, and the inhomogeneity of the silk fibroin/poly (ɛ-caprolactone) scaffolds with formic acid as solvent had a remarkable difference on cell adhesion and proliferation. In contrast, there was no significant difference among the silk fibroin/poly (ɛ-caprolactone) scaffolds with formic acid/acetic acid as solvent because of their good consistency in fiber morphology and composition. These obtained silk fibroin/poly (ɛ-caprolactone) nanofibers had small average diameter of 190 ± 40 nm. The obtained results proved that this study provided a facile and effective approach to achieve compositionally homogeneous silk fibroin/poly (ɛ-caprolactone) scaffolds with formic acid as solvent for effective applications. PMID:27422715

  11. Contemporaneous isolation of deoxyribonucleic acid-dependent ribonucleic acid polymerase and poly(A) polymerase from rat liver mitochondria.

    PubMed Central

    Gallerani, R; di Istituto; Istituto di, Ch; Saccone, C

    1976-01-01

    1. Poly(A) polymerase and DNA-dependent RNA polymerase from rat liver mitochondria can be completely separated by using two different chromatographic procedures. 2. Poly(A) polymerase can only incorporate ATP into acid-insoluble material and strongly depends on the addition of an endogenous factor (probably containing a mixture of oligoribonucleotides), but it is not stimulated by DNA. 3. RNA polymerase is fully DNA-dependent and rifampicin-sensitive, but was not stimulated by the endogenous factor mentioned above. 4. The chromatographic behaviour of the two enzymes, together with the properties described, suggest that they represent two different protein molecules. PMID:962867

  12. Accumulation of poly (3-hydroxybutyric acid) by some soil Streptomyces.

    PubMed

    Manna, A; Banerjee, R; Paul, A K

    1999-09-01

    In a limited-scale survey, 55 soil streptomycetes were screened for the accumulation of poly (3-hydroxybutyrate) [PHB]. Only 18% of the isolates accumulated PHB ranging between 1.9-7.8% of the dry biomass. The promising isolate DBCC-719, identified as Streptomyces griseorubiginosus, accumulated PHB amounting to 9.5% of the mycelial dry mass in the early stationary phase when grown in chemically defined medium with 2% (wt/vol) glucose as the sole source of carbon. Nitrogen-limiting conditions were inhibitory to growth and PHB accumulation. The isolated polymer was highly soluble in chloroform, gave a sharp peak at 235 nm on digestion with concentrated H(2)SO(4), and had a characteristic infrared spectrum. PMID:10441729

  13. Reinforced Poly(Propylene Carbonate) Composite with Enhanced and Tunable Characteristics, an Alternative for Poly(lactic Acid).

    PubMed

    Manavitehrani, Iman; Fathi, Ali; Wang, Yiwei; Maitz, Peter K; Dehghani, Fariba

    2015-10-14

    The acidic nature of the degradation products of polyesters often leads to unpredictable clinical complications, such as necrosis of host tissues and massive immune cell invasions. In this study, poly(propylene carbonate) (PPC) and starch composite is introduced with superior characteristics as an alternative to polyester-based polymers. The degradation products of PPC-starch composites are mainly carbon dioxide and water; hence, the associated risks to the acidic degradation of polyesters are minimized. Moreover, the compression strength of PPC-starch composites can be tuned over the range of 0.2±0.03 MPa to 33.9±1.51 MPa by changing the starch contents of composites to address different clinical needs. More importantly, the addition of 50 wt % starch enhances the thermal processing capacity of the composites by elevating their decomposition temperature from 245 to 276 °C. Therefore, thermal processing methods, such as extrusion and hot melt compression methods can be used to generate different shapes and structures from PPC-starch composites. We also demonstrated the cytocompatibility and biocompatibility of these composites by conducting in vitro and in vivo tests. For instance, the numbers of osteoblast cells were increased 2.5 fold after 7 days post culture. In addition, PPC composites in subcutaneous mice model resulted in mild inflammatory responses (e.g., the formation of fibrotic tissue) that were diminished from two to 4 weeks postimplantation. The long-term in vivo biodegradation of PPC composites are compared with poly(lactic acid) (PLA). The histochemical analysis revealed that after 8 weeks, the biodegradation of PLA leads to massive immune cell infusion and inflammation at the site, whereas the PPC composites are well-tolerated in vivo. All these results underline the favorable properties of PPC-starch composites as a benign biodegradable biomaterial for fabrication of biomedical implants. PMID:26376751

  14. Characterization of Active Packaging Films Made from Poly(Lactic Acid)/Poly(Trimethylene Carbonate) Incorporated with Oregano Essential Oil.

    PubMed

    Liu, Dong; Li, Hongli; Jiang, Lin; Chuan, Yongming; Yuan, Minglong; Chen, Haiyun

    2016-01-01

    Antimicromial and antioxidant bioactive films based on poly(lactic acid)/poly(trimenthylene carbonate) films incorporated with different concentrations of oregano essential oil (OEO) were prepared by solvent casting. The antimicrobial, antioxidant, physical, thermal, microstructural, and mechanical properties of the resulting films were examined. Scanning electron microscopy analysis revealed that the cross-section of films became rougher when OEO was incorporated into PLA/PTMC blends. Differential scanning calorimetry analysis indicated that crystallinity of PLA phase decreased by the addition of OEO, but this did not affect the thermal stability of the films. Water vapor permeability of films slightly increased with increasing concentration of OEO. However, active PLA/PTMC/OEO composite films showed adequate barrier properties for food packaging application. The antimicrobial and antioxidant capacities were significantly improved with the incorporation of OEO (p < 0.05). The results demonstrated that an optimal balance between the mechanical, barrier, thermal, antioxidant, and antimicrobial properties of the films was achieved by the incorporation of 9 wt % OEO into PLA/PTMC blends. PMID:27240336

  15. Poly(ethylene glycol)-poly(lactic-co-glycolic acid) based thermosensitive injectable hydrogels for biomedical applications.

    PubMed

    Alexander, Amit; Ajazuddin; Khan, Junaid; Saraf, Swarnlata; Saraf, Shailendra

    2013-12-28

    Stimuli triggered polymers provide a variety of applications related with the biomedical fields. Among various stimuli triggered mechanisms, thermoresponsive mechanisms have been extensively investigated, as they are relatively more convenient and effective stimuli for biomedical applications. In a contemporary approach for achieving the sustained action of proteins, peptides and bioactives, injectable depots and implants have always remained the thrust areas of research. In the same series, Poloxamer based thermogelling copolymers have their own limitations regarding biodegradability. Thus, there is a need to have an alternative biomaterial for the formulation of injectable hydrogel, which must remain biocompatible along with safety and efficacy. In the same context, poly(ethylene glycol) (PEG) based copolymers play a crucial role as a biomedical material for biomedical applications, because of their biocompatibility, biodegradability, thermosensitivity and easy controlled characters. This review stresses on the physicochemical property, stability and composition prospects of smart PEG/poly(lactic-co-glycolic acid) (PLGA) based thermoresponsive injectable hydrogels, recently utilized for biomedical applications. The manuscript also highlights the synthesis scheme and stability characteristics of these copolymers, which will surely help the researchers working in the same area. We have also emphasized the applied use of these smart copolymers along with their formulation problems, which could help in understanding the possible modifications related with these, to overcome their inherent associated limitations. PMID:24144918

  16. Biodegradability and mechanical properties of poly(butylene succinate) composites with finely dispersed hydrophilic poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Mizuno, Sawako; Hotta, Atsushi

    2014-03-01

    Biodegradability and mechanical properties of aliphatic poly(butylene succinate) (PBS) films with finely dispersed hydrophilic poly(acrylic acid) (PAA) were investigated. First, 3.5 wt% of PAA was chemically grafted onto the surface of the PBS films (surface-grafted PBS) by photo grafting polymerization, and then the grafted PAA was homogeneously and finely dispersed into PBS by dissolving the surface-grafted PBS into chloroform before mixing and drying to get solid PAA-dispersed PBS. Degradation of these modified PBS was investigated using gel permeation chromatography (GPC) and tensile testing. According to the GPC results, it was found that the PAA-dispersed PBS had intermediate biodegradability with the intermediate water intake, and the reaction constant of PAA-dispersed PBS was in between those of untreated PBS and surface-grafted PBS, in fact 25% higher and 17% lower, respectively. The experimental results presented that the biodegradability of PBS could be well controlled by the dispersion of PAA, possibly leading to the widespread use of PBS for biodegradable polymers.

  17. Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea.

    PubMed

    Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J; Hartmann, Laura; Cochran, Jennifer R; Frank, Curtis W; Yu, Charles Q; Ta, Christopher N

    2015-10-01

    We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications. PMID:25778285

  18. Response of Swelling Behavior of Weak Branched Poly(ethylene imine)/Poly(acrylic acid) Polyelectrolyte Multilayers to Thermal Treatment.

    PubMed

    Gu, Yuanqing; Weinheimer, Emily K; Ji, Xiang; Wiener, Clinton G; Zacharia, Nicole S

    2016-06-21

    Weak polyelectrolyte multilayers (PEMs) prepared by the layer-by-layer technique have attracted a great deal of attention as smart responsive materials for biological and other applications in aqueous medium, but their dynamic behavior as a function of exposure to a wide temperature range is still not well understood. In this work, the thermally dependent swelling behavior of PEMs consisting of branched poly(ethylenimine) and poly(acrylic acid) is studied by temperature controlled in situ spectroscopic ellipsometry. Because of diffusion and interpenetration of polyelectrolytes during film deposition, the PEMs densify with increasing bilayer number, which further affects their water uptake behavior. Upon heating to temperatures below 60 °C, the worsened solvent quality of the PEM in water causes deswelling of the PEMs. However, once heated above this critical temperature, the hydrogen bonds within the PEMs are weakened, which allows for chain rearrangement within the film upon cooling, resulting in enhanced water uptake and increased film thickness. The current work provides fundamental insight into the unique dynamic behavior of weak polyelectrolyte multilayers in water at elevated temperatures. PMID:27232180

  19. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    NASA Astrophysics Data System (ADS)

    Zou, Wei; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping

    2016-03-01

    Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

  20. Self-Healing Supramolecular Self-Assembled Hydrogels Based on Poly(L-glutamic acid).

    PubMed

    Li, Guifei; Wu, Jie; Wang, Bo; Yan, Shifeng; Zhang, Kunxi; Ding, Jianxun; Yin, Jingbo

    2015-11-01

    Self-healing polymeric hydrogels have the capability to recover their structures and functionalities upon injury, which are extremely attractive in emerging biomedical applications. This research reports a new kind of self-healing polypeptide hydrogels based on self-assembly between cholesterol (Chol)-modified triblock poly(L-glutamic acid)-block-poly(ethylene glycol)-block-poly(L-glutamic acid) ((PLGA-b-PEG-b-PLGA)-g-Chol) and β-cyclodextrin (β-CD)-modified poly(L-glutamic acid) (PLGA-g-β-CD). The hydrogel formation relied on the host and guest linkage between β-CD and Chol. This study demonstrates the influences of polymer concentration and β-CD/Chol molar ratio on viscoelastic behavior of the hydrogels. The results showed that storage modulus was highest at polymer concentration of 15% w/v and β-CD/Chol molar ratio of 1:1. The effect of the PLGA molecular weight in (PLGA-b-PEG-b-PLGA)-g-Chol on viscoelastic behavior, mechanical properties and in vitro degradation of the supramolecular hydrogels was also studied. The hydrogels showed outstanding self-healing capability and good cytocompatibility. The multilayer structure was constructed using hydrogels with self-healing ability. The developed hydrogels provide a fascinating glimpse for the applications in tissue engineering. PMID:26414083

  1. Enhanced human bone marrow stromal cell affinity for modified poly(L-lactide) surfaces by the upregulation of adhesion molecular genes.

    PubMed

    Mao, Xueli; Peng, Hui; Ling, Junqi; Friis, Thor; Whittaker, Andrew K; Crawford, Ross; Xiao, Yin

    2009-12-01

    To enhance and regulate cell affinity for poly (L-lactic acid) (PLLA) based materials, two hydrophilic ligands, poly (ethylene glycol) (PEG) and poly (L-lysine) (PLL), were used to develop triblock copolymers: methoxy-terminated poly (ethylene glycol)-block-poly (L-lactide)-block-poly (L-lysine) (MPEG-b-PLLA-b-PLL) in order to regulate protein absorption and cell adhesion. Bone marrow stromal cells (BMSCs) were cultured on different composition of MPEG-b-PLLA-b-PLL copolymer films to determine the effect of modified polymer surfaces on BMSC attachment. To understand the molecular mechanism governing the initial cell adhesion on difference polymer surfaces, the mRNA expression of 84 human extracellular matrix (ECM) and adhesion molecules was analysed using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). It was found that down regulation of adhesion molecules was responsible for the impaired BMSC attachment on PLLA surface. MPEG-b-PLLA-b-PLL copolymer films improved significantly the cell adhesion and cytoskeleton expression by upregulation of relevant molecule genes significantly. Six adhesion genes (CDH1, ITGL, NCAM1, SGCE, COL16A1, and LAMA3) were most significantly influenced by the modified PLLA surfaces. In summary, polymer surfaces altered adhesion molecule gene expression of BMSCs, which consequently regulated cell initial attachment on modified PLLA surfaces. PMID:19796804

  2. Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

    NASA Astrophysics Data System (ADS)

    Cheng, Jing; Lawson, Richard A.; Yeh, Wei-Ming; Jarnagin, Nathan D.; Peters, Andrew; Tolbert, Laren M.; Henderson, Clifford L.

    2012-03-01

    Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (Mw=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L0) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which

  3. Poly(lactic acid)-poly(ethylene glycol) nanoparticles as new carriers for the delivery of plasmid DNA.

    PubMed

    Perez, C; Sanchez, A; Putnam, D; Ting, D; Langer, R; Alonso, M J

    2001-07-10

    The purpose of the present work was to produce and characterize poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) nanoparticles (size lower than 300 nm) containing a high loading of plasmid DNA in a free form or co-encapsulated with either poly(vinyl alcohol) (PVA) or poly(vinylpyrrolidone) (PVP). The plasmid alone or with PVA or PVP was encapsulated by two different techniques: an optimized w/o/w emulsion-solvent evaporation technique as well as by a new w/o emulsion-solvent diffusion technique. Particle size, zeta potential, plasmid DNA loading and in vitro release were determined for the three plasmid-loaded formulations. The influence of the initial plasmid loadings (5, 10, 20 microg plasmid DNA/mg PLA-PEG) on those parameters was also investigated. The plasmid loaded into the nanoparticles and released in vitro was quantified by fluorimetry and the different molecular forms were identified by gel electrophoresis. PLA-PEG nanoparticles containing plasmid DNA in a free form or co-encapsulated with PVA or PVP were obtained in the range size of 150-300 nm and with a negative zeta potential, both parameters being affected by the preparation technique. Encapsulation efficiencies were high irrespective of the presence of PVA or PVP (60-90%) and were slightly affected by the preparation technique and by the initial loading. The final plasmid DNA loading in the nanoparticles was up to 10-12 microg plasmid DNA/mg polymer. Plasmid DNA release kinetics varied depending on the plasmid incorporation technique: nanoparticles prepared by the w/o diffusion technique released their content rapidly whereas those obtained by the w/o/w showed an initial burst followed by a slow release for at least 28 days. No significant influence of the plasmid DNA loading and of the co-encapsulation of PVP or PVA on the in vitro release rate was observed. In all cases the conversion of the supercoiled form to the open circular and linear forms was detected. In conclusion, plasmid DNA can be

  4. The regulatory effect of citric acid on the co-production of poly(ε-lysine) and poly(L-diaminopropionic acid) in Streptomyces albulus PD-1.

    PubMed

    Xia, Jun; Xu, Zhaoxian; Xu, Hong; Feng, Xiaohai; Bo, Fangfang

    2014-10-01

    Streptomyces albulus PD-1 can co-produce antimicrobial homo-polymers poly(ε-lysine) (ε-PL) and poly(L-diaminopropionic acid) (PDAP). In this study, a novel feeding strategy of citric acid coupled with glucose-(NH4)2SO4 feeding was employed to S. albulus PD-1. When the pH of the culture broth dropped to 4.0, the feeding solution was added continuously to maintain the concentrations of glucose and citric acid at 10 and 4 g L(-1), respectively. As a result, the final concentration of ε-PL increased from 21.7 to 29.7 g L(-1) and the final concentration of PDAP decreased from 4.8 to 3.2 g L(-1). Assays on intracellular nucleotide levels and key enzyme activities were performed to elucidate the underlying regulation mechanism. The addition of citric acid increased NADH/NAD(+) ratio and decreased intracellular ATP level; meanwhile, the activities of pyruvate kinase, citrate synthase and isocitrate dehydrogenase decreased while aspartate aminotransferase activity increased. Therefore, we deduced that citric acid feeding resulted in metabolic flux redistribution at the node of phosphoenolpyruvate; the metabolic pathway from phosphoenolpyruvate directed into tricarboxylic acid cycle was weakened and thus PDAP production was inhibited. On the other hand, the metabolic pathway from phosphoenolpyruvate directed into oxaloacetate and L-aspartate was enhanced, thereby improving ε-PL production. This fermentation strategy may be potentially useful in ε-PL production because it can effectively inhibit the formation of by-products, such as PDAP. PMID:24752482

  5. Water-Soluble Poly(p-aryleneethynylene)s: A Sensor Array Discriminates Aromatic Carboxylic Acids.

    PubMed

    Han, Jinsong; Wang, Benhua; Bender, Markus; Seehafer, Kai; Bunz, Uwe H F

    2016-08-10

    A chemical tongue consisting of 11 elements (four poly(p-aryleneethynylene)s (PAE) at pH 7 and pH 13, and seven electrostatic complexes formed from oppositely charged poly(p-aryleneethynylene)s at pH 7) discriminate 21 benzoic and phenylacetic acid derivatives in aqueous solution. The mechanism of discrimination is the fluorescence modulation of the PAEs, leading to quenching or fluorescence turn-on. The PAEs alone at both pH values and the tongue, consisting of the complexes only, discriminate the 21 acids with 92% (PAEs at pH 7), 95% (PAEs at pH 13), and 99% (complexes at pH 7) reliability after linear discriminant analysis (LDA). A sensor field with all 14 elements, according to LDA, discriminates all of the 21 acids with 100% accuracy. PMID:27415439

  6. Biocompatibility and bone-repairing effects: comparison between porous poly-lactic-co-glycolic acid and nano-hydroxyapatite/poly(lactic acid) scaffolds.

    PubMed

    Zong, Chen; Qian, Xiaodan; Tang, Zihua; Hu, Qinghong; Chen, Jiarong; Gao, Changyou; Tang, Ruikang; Tong, Xiangmin; Wang, Jinfu

    2014-06-01

    Copolymer composite scaffolds and bioceramic/polymer composite scaffolds are two representative forms of composite scaffolds used for bone tissue engineering. Studies to compare biocompatibility and bone-repairing effects between these two scaffolds are significant for selecting or improving the scaffold for clinical application. We prepared two porous scaffolds comprising poly-lactic-acid/poly-glycolic-acid (PLGA) and poly-lactic-acid/nano-hydroxyapatite (nHAP/PLA) respectively, and examined their biocompatibility with human bone marrow-derived mesenchymal stem cells (hMSCs) through evaluating adhesion, proliferation and osteogenic differentiation potentials of hMSCs in the scaffold. Then, the PLGA scaffold with hMSCs (PM construct) and the nHAP/PLA scaffold with hMSCs (HPM construct) were transplanted into the rat calvarial defect areas to compare their effects on the bone reconstruction. The results showed that the nHAP/PLA scaffold was in favor of adhesion, matrix deposition and osteogenic differentiation of hMSCs. For in vivo transplantation, both HPM and PM constructs led to mineralization and osteogenesis in the defect area of rat. However, the area grafted with PM construct showed a better formation of mature bone than that with HPM construct. In addition, the evaluation of in vitro and in vivo degradation indicated that the degradation rate of nHAP/PLA scaffold was much lower than that of PLGA scaffold. It is inferred that the lower degradation of nHAP/PLA scaffold should result in its inferior bone reconstruction in rat calvaria. Therefore, the preparation of an ideal composite scaffold for bone tissue engineering should be taken into account of the balance between its biocompatibility, degradation rate, osteoconductivity and mechanical property. PMID:24749403

  7. Poly(acrylic acid)-block-poly(vinyl alcohol) anchored maghemite nanoparticles designed for multi-stimuli triggered drug release

    NASA Astrophysics Data System (ADS)

    Liu, Ji; Detrembleur, Christophe; Debuigne, Antoine; de Pauw-Gillet, Marie-Claire; Mornet, Stéphane; Vander Elst, Luce; Laurent, Sophie; Labrugère, Christine; Duguet, Etienne; Jérôme, Christine

    2013-11-01

    Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene blue (MB), a cationic model drug. The triggered release of MB was studied under various stimuli such as pH, ionic strength and temperature. Local heating generated under alternating magnetic field (AMF) application was studied, and remotely AMF-triggered release was also confirmed, while a mild heating-up of the release medium was observed. Furthermore, their potential application as magnetic resonance imaging (MRI) contrast agents was explored via relaxivity measurements and acquisition of T2-weighted images. Preliminary studies on the cytotoxicity against mouse fibroblast-like L929 cell line and also their cellular uptake within human melanoma MEL-5 cell line were carried out. In conclusion, this kind of stimuli-responsive nanoparticles appears to be promising carriers for delivering drugs to some tumour sites or into cellular compartments with an acidic environment.Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene

  8. Production of D-lactic acid by bacterial fermentation of rice starch.

    PubMed

    Fukushima, Kazuki; Sogo, Kazuaki; Miura, Shigenobu; Kimura, Yoshiharu

    2004-11-20

    D-Lactic acid was synthesized by the fermentation of rice starch using microorganisms. Two species: Lactobacillus delbrueckii and Sporolactobacillus inulinus were found to be active in producing D-lactic acid of high optical purity after an intensive screening test for D-lactic acid bacteria using glucose as substrate. Rice powder used as the starch source was hydrolyzed with a combination of enzymes: alpha-amylase, beta-amylase, and pullulanase to obtain rice saccharificate consisting of maltose as the main component. Its average gross yield was 82.5%. Of the discovered D-lactic acid bacteria, only Lactobacillus delbrueckii could ferment both maltose and the rice saccharificate. After optimizing the fermentation of the rice saccharificate using this bacterium, pilot scale fermentation was conducted to convert the rice saccharificate into D-lactic acid with a D-content higher than 97.5% in a yield of 70%. With this yield, the total yield of D-lactic acid from brown rice was estimated to be 47%, which is almost equal to the L-lactic acid yield from corn. The efficient synthesis of D-lactic acid can open a way to the large scale application of high-melting poly(lactic acid) that is a stereocomplex of poly(L-lactide) and poly(D-lactide). Schematic representation of the production of D-lactic acid starting from brown rice as described here. PMID:15529396

  9. New synthesis method of HA/P(D,L)LA composites: study of fibronectin adsorption and their effects in osteoblastic behavior for bone tissue engineering.

    PubMed

    Yala, Sabeha; Boustta, Mahfoud; Gallet, Olivier; Hindié, Mathilde; Carreiras, Franck; Benachour, Hamanou; Sidane, Djahida; Khireddine, Hafit

    2016-09-01

    A novel synthetic method to synthesize hydroxyapatite/poly (D,L) lactic acid biocomposite is presented in this study by mixing only the precursors hydroxyapatite and (D,L) LA monomer without adding neither solvent nor catalyst. Three compositions were successfully synthesized with the weight ratios of 1/1, 1/3, and 3/5 (hydroxyapatite/(D,L) lactic acid), and the grafting efficiency of poly (D,L) lactic acid on hydroxyapatite surface reaches up to 84 %. Scanning electron microscopy and Fourier transform infrared spectroscopy showed that the hydroxyapatite particles were successfully incorporated into the poly (D,L) lactic acid polymer and X ray diffraction analysis showed that hydroxyapatite preserved its crystallinity after poly (D,L) lactic acid grafting. Differential scanning calorimetry shows that Tg of hydroxyapatite/poly (D,L) lactic acid composite is less than Tg of pure poly (D,L) lactic acid, which facilitates the shaping of the composite obtained. The addition of poly (D,L) lactic acid improves the adsorption properties of hydroxyapatite for fibronectin extracellular matrix protein. Furthermore, the presence of poly (D,L) lactic acid on hydroxyapatite surface coated with fibronectin enhanced pre-osteoblast STRO-1 adhesion and cell spreading. These results show the promising potential of hydroxyapatite/poly (D,L) lactic acid composite as a bone substitute material for orthopedic applications and bone tissue engineering. PMID:27534400

  10. Synthesis of poly(anilineboronic acid) nanofibers for electrochemical detection of glucose.

    PubMed

    Li, Guicun; Li, Yingmei; Peng, Hongrui; Chen, Kezheng

    2011-08-01

    Poly(anilineboronic acid) (PABA) nanofibers with U-shaped and ring-shaped morphologies have been synthesized successfully by chemical polymerization of 3-aminophenylboronic acid (APBA) in the presence of cetyltrimethylammonium bromide (CTAB) and NaF. The morphologies and sizes of PABA nanofibers can be controlled by adjusting the synthetic parameters, such as the concentrations of CTAB and APBA. The U-shaped PABA nanofibers exhibit excellent electrochemical redox activity and high sensitive detection of D-glucose in phosphate-buffered saline stock solution (pH 7.4) because of their high effective surface area as well as the high density of boronic acid groups. PMID:21692122

  11. Poly(L-diaminopropionic acid), a novel non-proteinic amino acid oligomer co-produced with poly(ε-L-lysine) by Streptomyces albulus PD-1.

    PubMed

    Xia, Jun; Xu, Hong; Feng, Xiaohai; Xu, Zhaoxian; Chi, Bo

    2013-09-01

    Poly(ε-L-lysine) (ε-PL) producer strain Streptomyces albulus PD-1 secreted a novel polymeric substance into its culture broth along with ε-PL. The polymeric substance was purified to homogeneity and identified. Matrix-assisted laser desorption ionization-time of flight mass spectrometry and nuclear magnetic resonance spectroscopy as well as other analytical techniques revealed that the substance was poly(L-diaminopropionic acid) (PDAP). PDAP is an L-α,β-diaminopropionic acid oligomer linking between amino and carboxylic acid functional groups. The molecular weight of PDAP ranged from 500 to 1500 Da, and no co-polymers composed of L-diaminopropionic acid and L-lysine were present in the culture broth. Compared with ε-PL, PDAP exhibited stronger inhibitory activities against yeasts but weaker activities against bacteria. ε-PL and PDAP co-production was also investigated. Both ε-PL and PDAP were synthesized during the stationary phase of growth, and the final ε-PL and PDAP concentration reached 21.7 and 4.8 g L(-1), respectively, in fed-batch fermentation. Citric acid feeding resulted in a maximum ε-PL concentration of 26.1 g L(-1) and a decrease in the final concentration of PDAP to 3.8 g L(-1). No studies on ε-PL and PDAP co-production in Streptomyces albulus have been reported previously, and inhibition of by-products such as PDAP is potentially useful in ε-PL production. PMID:23775267

  12. SYNTHESIS AND CHARACTERIZATION OF SUBSTITUTED POLY(STYRENE)-b-POLY(ACRYLIC ACID) BLOCK COPOLYMER MICELLES

    SciTech Connect

    Pickel, Deanna L; Pickel, Joseph M; Devenyi, Jozsef; Britt, Phillip F

    2009-01-01

    Block copolymer micelle synthesis and characterization has been extensively studied. In particular, most studies have focused on the properties of the hydrophilic corona due to the micelle corona structure s impact on the biodistribution and biocompatibility. Unfortunately, less attention has been given to the effect of the core block on the micelle stability, morphology, and the rate of diffusion of small molecules from the core. This investigation is focused on the synthesis of block copolymers composed of meta-substituted styrenes and acrylic acid by Atom Transfer Radical Polymerization. Micelles with cores composed of substituted styrenes having Tgs ranging from -30 to 100 oC have been prepared and the size and shape of these micelles were characterized by Static and Dynamic Light Scattering and TEM. In addition, the critical micelle concentration and rate of diffusion of small molecules from the core were determined by fluorimetry using pyrene as the probe.

  13. The Chemical and Physical Properties of Poly(ε-caprolactone) Scaffolds Functionalised with Poly(vinyl phosphonic acid-co-acrylic acid).

    PubMed

    Bassi, A K; Gough, J E; Zakikhani, M; Downes, S

    2011-01-01

    There is a clinical need for a synthetic alternative to bone graft substitute (BGS) derived from demineralised bone matrix. We report the electrospinning of Poly(ε-caprolactone) (PCL) to form a 3-dimensional scaffold for use as a synthetic BGS. Additionally, we have used Poly(vinyl phosphonic acid-co-acrylic acid) (PVPA) to improve bone formation. Fibres were formed using a 10% w/v PCL/acetone solution. Infrared spectroscopy confirmed that the electrospinning process had no effect on the functional groups present in the resulting structure. The electrospun scaffolds were coated with PVPA (PCL/PVPA), and characterised. The stability of the PVPA coating after immersion in culture medium was assessed over 21 days. There was rapid release of the coating until day 2, after which the coating became stable. The wettability of the PCL scaffolds improved significantly, from 123.3 ± 10.8° to 43.3 ± 1.2° after functionalisation with PVPA. The compressive strength of the PCL/PVPA scaffolds (72 MPa) was significantly higher to that of the PCL scaffold (14 MPa), and an intermediate between trabecular and cortical bone (7 MPa and 170 MPa, resp.). The study has demonstrated that the PCL/PVPA scaffold has the desired chemical and biomechanical characteristics required for a material designed to be used as a BGS. PMID:22073379

  14. The Chemical and Physical Properties of Poly(ε-caprolactone) Scaffolds Functionalised with Poly(vinyl phosphonic acid-co-acrylic acid)

    PubMed Central

    Bassi, A. K.; Gough, J. E.; Zakikhani, M.; Downes, S.

    2011-01-01

    There is a clinical need for a synthetic alternative to bone graft substitute (BGS) derived from demineralised bone matrix. We report the electrospinning of Poly(ε-caprolactone) (PCL) to form a 3-dimensional scaffold for use as a synthetic BGS. Additionally, we have used Poly(vinyl phosphonic acid-co-acrylic acid) (PVPA) to improve bone formation. Fibres were formed using a 10% w/v PCL/acetone solution. Infrared spectroscopy confirmed that the electrospinning process had no effect on the functional groups present in the resulting structure. The electrospun scaffolds were coated with PVPA (PCL/PVPA), and characterised. The stability of the PVPA coating after immersion in culture medium was assessed over 21 days. There was rapid release of the coating until day 2, after which the coating became stable. The wettability of the PCL scaffolds improved significantly, from 123.3 ± 10.8° to 43.3 ± 1.2° after functionalisation with PVPA. The compressive strength of the PCL/PVPA scaffolds (72 MPa) was significantly higher to that of the PCL scaffold (14 MPa), and an intermediate between trabecular and cortical bone (7 MPa and 170 MPa, resp.). The study has demonstrated that the PCL/PVPA scaffold has the desired chemical and biomechanical characteristics required for a material designed to be used as a BGS. PMID:22073379

  15. Molecular Dynamics Simulations of Adsorption of Poly(acrylic acid) and Poly(methacrylic acid) on Dodecyltrimethylammonium Chloride Micelle in Water: Effect of Charge Density.

    PubMed

    Sulatha, Muralidharan S; Natarajan, Upendra

    2015-09-24

    We have investigated the interaction of dodecyltrimethylammonium chloride (DoTA) micelle with weak polyelectrolytes, poly(acrylic acid) and poly(methacrylic acid). Anionic as well as un-ionized forms of the polyelectrolytes were studied. Polyelectrolyte-surfactant complexes were formed within 5-11 ns of the simulation time and were found to be stable. Association is driven purely by electrostatic interactions for anionic chains whereas dispersion interactions also play a dominant role in the case of un-ionized chains. Surfactant headgroup nitrogen atoms are in close contact with the carboxylic oxygens of the polyelectrolyte chain at a distance of 0.35 nm. In the complexes, the polyelectrolyte chains are adsorbed on to the hydrophilic micellar surface and do not penetrate into the hydrophobic core of the micelle. Polyacrylate chain shows higher affinity for complex formation with DoTA as compared to polymethacrylate chain. Anionic polyelectrolyte chains show higher interaction strength as compared to corresponding un-ionized chains. Anionic chains act as polymeric counterion in the complexes, resulting in the displacement of counterions (Na(+) and Cl(-)) into the bulk solution. Anionic chains show distinct shrinkage upon adsorption onto the micelle. Detailed information about the microscopic structure and binding characteristics of these complexes is in agreement with available experimental literature. PMID:26355463

  16. Star-shaped polymers of bio-inspired algae core and poly(acrylamide) and poly(acrylic acid) as arms in dissolution of silica/silicate.

    PubMed

    Chauhan, Kalpana; Patiyal, Priyanka; Chauhan, Ghanshyam S; Sharma, Praveen

    2014-06-01

    Silica, in natural waters (due to weathering of rocks) decreases system performance in water processing industry due to scaling. In view of that, the present work involves the synthesis of novel green star shaped additives of algae core (a bio-inspired material as diatom maintains silicic acid equilibrium in sea water) as silica polymerization inhibitors. Star shaped materials with bio-inspired core and poly(acrylamide) [poly(AAm)] and poly(acrylic acid) [poly(AAc)] arms were synthesized by economical green approach. The proficiency was evaluated in 'mini lab' scale for the synthesized APAAm (Algae-g-poly(AAm)) and APAAc (Algae-g-poly(AAc)) dendrimers (star shaped) in colloidal silica mitigation/inhibition at 35 °C and 55 °C. Synthesized dendrimers were equally proficient in silica inhibition at 12 h and maintains ≥450 ppm soluble silica. However, APAAm dendrimers of generation 0 confirmed better results (≈300 ppm) in contrast to APAAc dendrimers in silica inhibition at 55 °C. Additionally, dendrimers also worked as a nucleator for heterogeneous polymerization to inhibit silica homo-polymerization. APAAm dendrimer test set showed no silica deposit for more than 10 days of inhibition. EDX characterization results support nucleator mechanism with Si content of 6.97%-10.98% by weight in silica deposits (SiO2-APAAm dendrimer composites). PMID:24681378

  17. Study of the miscibility of poly(styrene-co-4-vinylbenzoic acid) with poly(ethyl methacrylate) or with poly[ethyl methacrylate-co-(2-N,N-dimethylaminoethyl) methacrylate] by inverse gas chromatography.

    PubMed

    Ourdani, Samia; Amrani, Farouk

    2002-09-01

    Poly(styrene) is immiscible with poly(ethyl methacrylate). The introduction of a small amount of 4-vinylbenzoic acid units along poly(styrene) chains (PS-VBA) enhanced its miscibility with poly(ethyl methacrylate) (PEMA) or with poly[ethyl methacrylate-co-(2-N,N-dimethylaminoethyl) methacrylate] (PEMA-DAE), as observed from the appearance of a single composition dependent glass transition temperature for each binary system using inverse gas chromatography. The negative values of the apparent polymer-polymer interaction parameter, chi(23)app, determined with different families of molecular probes, for three blend compositions and over a range of temperature confirm quantitatively the miscibility of these blends. The chi(23)app values for PEMA(PS-VBA) and (PEMA-DAE)-(PS-VBA) blends are dependent of the chemical nature of the probes, the temperature and the blend composition. PMID:12385399

  18. Preparation of Poly Acrylic Acid-Poly Acrylamide Composite Nanogels by Radiation Technique

    PubMed Central

    Ghorbaniazar, Parisa; Sepehrianazar, Amir; Eskandani, Morteza; Nabi-Meibodi, Mohsen; Kouhsoltani, Maryam; Hamishehkar, Hamed

    2015-01-01

    Purpose: Nanogel, a nanoparticle prepared from a cross-linked hydrophilic polymer network, has many biomedical applications. A radiation technique has recently been introduced as one of the appropriate methods for the preparation of polymeric nanogels due to its additive-free initiation and easy control procedure. Methods: We have investigated the formation of nano-sized polymeric gels, based on the radiation-induced inter- and intra-molecular cross-linking of the inter-polymer complex (IPC) of polyacrylamide (PAAm) and polyacrylic acide (PAAc). Results: The results indicated that the prepared polymeric complex composed of PAAm and PAAc was converted into nanogel by irradiation under different doses (1, 3, 5 and 7 kGy). This was due to inter- and intra-molecular cross-linking at the range of 446-930 nm as characterized by the photon correlation spectroscopy method. Increasing the irradiation dose reduced the size of nanoparticles to 3 kGy; however, the higher doses increased the size and size distribution. Scanning electron microscopy images indicated the nanogel formation in the reported size by particle size and showed the microcapsule structure of the prepared nanogels. Biocompatibility of nanogels were assessed and proved by MTT assay. Conclusion: It was concluded that low dose irradiation can be successfully applied for nanometre-ranged hydrogel. PMID:26236667

  19. A study on reactive blending of (poly lactic acid) and poly (butylene succinate co adipate)

    NASA Astrophysics Data System (ADS)

    Bureepukdee, C.; Suttiruengwong, S.; Seadan, M.

    2015-07-01

    This research aims to study the blending of Polylactic acid (PLA) and Polybutylene succinate co adipate (PBSA) in order to understand the role of peroxide in free radical reaction on the compatibilization between these two biodegradable polyesters. Various ratios of PLA/PBSA blends with and without reactive agents were prepared in the twin screw extruder. Two types of peroxides, Di (tert-butylperoxyisopropyl) benzene (DTBP) and 2, 5-Dimethyl-2, 5-(t-butylperoxy) hexane (DTBH), were used with various concentrations to compare. From the torques measurement, DTBP was more reactive with PLA and PBSA than DTBH. PLA and PBSA 80:20, 60:40, 50:50, 40:60, and 20:80% by weight were melt-blended in a twin screw extruder. The reactive polymer blends were also prepared for the same ratios of the blends with addition of 0.08 and 0.1 phr of DTBP. The mechanical, thermal, rheological, and morphological properties were investigated. The impact strengths of the non-reactive blend increased with the increasing in PBSA content. The optimal impact strength was obtained at 40%wt of PBSA with 0.1 phr of DTBP. Adding 0.08 and 0.1 phr of DTBP led to the co continuous phase morphology of PLA/PBSA blends. The per cent crystallinity of PLA increased when blended with PBSA. PBSA might induce the crystallization of PLA.

  20. Poly (lactic-co-glycolic acid) controlled release systems: experimental and modeling insights

    PubMed Central

    Hines, Daniel J.; Kaplan, David L.

    2013-01-01

    Poly-lactic-co-glycolic acid (PLGA) has been the most successful polymeric biomaterial for use in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in drug release device formulation. Mathematical modeling is a useful tool for identifying, characterizing, and predicting the mechanisms of controlled release. The advantages and limitations of poly (lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled release technology that utilize PLGA. Mathematical modeling applied towards controlled release rates from PLGA-based devices will also be discussed to provide a complete picture of state of the art understanding of the control achievable with this polymeric system, as well as the limitations. PMID:23614648

  1. Anticancer drug release from poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels

    NASA Astrophysics Data System (ADS)

    Taşdelen, B.; Kayaman-Apohan, N.; Güven, O.; Baysal, B. M.

    2005-08-01

    The drug uptake and release of anticancer drug from N-isopropylacrylamide/itaconic acid copolymeric hydrogels containing 0-3 mol% of itaconic acid irradiated at 48 kGy have been investigated. 5-Fluorouracil (5-FU) is used as a model anticancer drug. The effect of 5-FU solution on swelling characteristics of PNIPAAm and P(NIPAAm/IA) copolymeric hydrogels have also been studied. The percent swelling, equilibrium swelling, equilibrium water/5-FU content and diffusion constant values are evaluated for poly(N-isopropylacrylamide) (PNIPAAm) and poly(N-isopropylacrylamide/itaconic) (P(NIPAAm/IA)) hydrogels at 130 ppm of 5-FU solution at room temperature. Diffusion of 5-FU solution into the hydrogels has been found to be the non-Fickian type. Finally, the kinetics of drug release from the hydrogels are examined.

  2. Preparation of poly(acrylic acid) particles by dispersion polymerization in an ionic liquid.

    PubMed

    Minami, Hideto; Kimura, Akira; Kinoshita, Keigo; Okubo, Masayoshi

    2010-05-01

    Poly(acrylic acid) (PAA) particles were successfully prepared by dispersion polymerization of acrylic acid in ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoro-methanesulfonyl)amide ([DEME][TFSA]) at 70 degrees C with low hydrolysis grade (35.4%) poly(vinyl alcohol) as stabilizer. Interestingly, the PAA particles were easily extracted as particle state with water. Thus, the PAA particles had a cross-linked structure during the polymerization without cross-linker. Moreover, it was also noted that the cross-linking density of the PAA particles could be controlled by thermal treatment at various temperatures in [DEME][TFSA] utilizing the advantages of nonvolatility and high thermal stability of the ionic liquid. PMID:20043688

  3. Preparation of poly(lactic acid) composite hollow spheres containing calcium carbonates.

    PubMed

    Maeda, Hirotaka; Kasuga, Toshihiro

    2006-07-01

    Poly(lactic acid) composite hollow spheres containing calcium carbonate were prepared by oil-in-water emulsion evaporation to develop injectable bone substitutes incorporated with cells. The spheres were approximately 1.2mm in diameter and had a shell with a thickness in the range of 50-150microm. The hollow in the spheres was presumed to be formed by CO(2) gas generated by the decomposition of vaterite used as a starting material. An open channel approximately 800microm in diameter was formed in the spheres by chemical etching utilizing the rapid dissolution of poly(lactic acid) at the thin portion of the shell. Cells could migrate into the hollow spheres through the open channel and attach to the inner surface. PMID:16765880

  4. Poly(N-vinylimidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids.

    PubMed

    Schemeth, Dieter; Noël, Jean-Christophe; Jakschitz, Thomas; Rainer, Matthias; Tessadri, Richard; Huck, Christian W; Bonn, Günther K

    2015-07-23

    In this study we report the novel polymeric resin poly(N-vinyl imidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids. The monomer to crosslinker ratio and the porogen composition were optimized for isolating phenolic acids diluted in acetonitrile at normal phase chromatography conditions, first. Acetonitrile serves as polar, aprotic solvent, dissolving phenolic acids but not interrupting interactions with the stationary phase due to the approved Hansen solubility parameters. The optimized resin demonstrated high loading capacities and adsorption abilities particularly for phenolic acids in both, acetonitrile and aqueous solutions. The adsorption behavior of aqueous standards can be attributed to ion exchange effects due to electrostatic interactions between protonated imidazole residues and deprotonated phenolic acids. Furthermore, adsorption experiments and subsequent curve fittings provide information of maximum loading capacities of single standards according to the Langmuir adsorption model. Recovery studies of the optimized polymer in the normal-phase and ion-exchange mode illustrate the powerful isolation properties for phenolic acids and are comparable or even better than typical, commercially available solid phase extraction materials. In order to prove the applicability, a highly complex extract of rosemary leaves was purified by poly(N-vinyl imidazole/ethylene glycol dimethacrylate) and the isolated compounds were identified using UHPLC-qTOF-MS. PMID:26231906

  5. A simple and robust method for pre-wetting poly (lactic-co-glycolic) acid microspheres

    PubMed Central

    Wright, Bernice; Parmar, Nina; Bozec, Laurent; Aguayo, Sebastian D

    2015-01-01

    Poly (lactic-co-glycolic) acid microspheres are amenable to a number of biomedical procedures that support delivery of cells, drugs, peptides or genes. Hydrophilisation or wetting of poly (lactic-co-glycolic) acid are an important pre-requisites for attachment of cells and can be achieved via exposure to plasma oxygen or nitrogen, surface hydrolysis with NaOH or chloric acid, immersion in ethanol and water, or prolonged incubation in phosphate buffered saline or cell culture medium. The aim of this study is to develop a simple method for wetting poly (lactic-co-glycolic) acid microspheres for cell delivery applications. A one-step ethanol immersion process that involved addition of serum-supplemented medium and ethanol to PLGA microspheres over 30 min–24 h is described in the present study. This protocol presents a more efficient methodology than conventional two-step wetting procedures. Attachment of human skeletal myoblasts to poly (lactic-co-glycolic) acid microspheres was dependent on extent of wetting, changes in surface topography mediated by ethanol pre-wetting and serum protein adsorption. Ethanol, at 70% (v/v) and 100%, facilitated similar levels of wetting. Wetting with 35% (v/v) ethanol was only achieved after 24 h. Pre-wetting (over 3 h) with 70% (v/v) ethanol allowed significantly greater (p ≤ 0.01) serum protein adsorption to microspheres than wetting with 35% (v/v) ethanol. On serum protein-loaded microspheres, greater numbers of myoblasts attached to constructs wetted with 70% ethanol than those partially wetted with 35% (v/v) ethanol. Microspheres treated with 70% (v/v) ethanol presented a more rugose surface than those treated with 35% (v/v) ethanol, indicating that more efficient myoblast adhesion to the former may be at least partially attributed to differences in surface structure. We conclude that our novel protocol for pre-wetting poly (lactic-co-glycolic) acid microspheres that incorporates biochemical and structural features

  6. Design of experiments reveals critical parameters for pilot-scale freeze-and-thaw processing of L-lactic dehydrogenase.

    PubMed

    Roessl, Ulrich; Humi, Sebastian; Leitgeb, Stefan; Nidetzky, Bernd

    2015-09-01

    Freezing constitutes an important unit operation of biotechnological protein production. Effects of freeze-and-thaw (F/T) process parameters on stability and other quality attributes of the protein product are usually not well understood. Here a design of experiments (DoE) approach was used to characterize the F/T behavior of L-lactic dehydrogenase (LDH) in a 700-mL pilot-scale freeze container equipped with internal temperature and pH probes. In 24-hour experiments, target temperature between -10 and -38°C most strongly affected LDH stability whereby enzyme activity was retained best at the highest temperature of -10°C. Cooling profile and liquid fill volume also had significant effects on LDH stability and affected the protein aggregation significantly. Parameters of the thawing phase had a comparably small effect on LDH stability. Experiments in which the standard sodium phosphate buffer was exchanged by Tris-HCl and the non-ionic surfactant Tween 80 was added to the protein solution showed that pH shift during freezing and protein surface exposure were the main factors responsible for LDH instability at the lower freeze temperatures. Collectively, evidence is presented that supports the use of DoE-based systematic analysis at pilot scale in the identification of F/T process parameters critical for protein stability and in the development of suitable process control strategies. PMID:25820483

  7. The poly(adenylic acid)-protein complex is restricted to the nonpolysomal messenger ribonucleoprotein of Physarum polycephalum.

    PubMed

    Adams, D S; Noonan, D; Jeffery, W R

    1980-04-29

    The distribution of poly(adenylic acid) [poly(A)]-protein complexes in the polysomal and nonpolysomal messenger ribonucleoprotein (mRNP) fractions of Physarum polycephalum was examined in the present study. Poly-(A)-containing components released from the nonpolysomal mRNP by ribonuclease (RNase) digestion were quantitatively adsorbed to nitrocellulose filters at low ionic strength, were highly resistant to micrococcal nuclease under conditions in which free poly(A) was completely degraded, and sedimented as a 10-15S particle which was disrupted by sodium dodecyl sulfate and protease treatment. These are characteristics of the poly(A)-protein complex. In contrast,poly(A)-containing molecules released from the polysomes by RNase were refractive to nitrocellulose, were completely sensitive to micrococcal nuclease, and sedimented at 2-4 S, identical with the sedimentation exhibited by protein-free poly(A). Examination of the poly(A) sequences present in polysomal and nonpolysomal mRNP by polyacylamide gel electrophoresis showed that the former contained only very short sequences, averaging approximately 15 nucleotides, while the latter exhibited only much longer segments, averaging approximately 65 nucleotides. It is concluded that poly(A)-protein complexes are restricted to the nonpolysomal mRNP of Physarum and that the limiting factor in complex formation may be the length of the available poly(A) binding site. PMID:7378386

  8. Electrospraying and Electrospinning of Polymers for Biomedical Applications. Poly(Lactic-Co-Glycolic Acid) and Poly(Ethylene-Co-Vinylacetate). Appendix 2

    NASA Technical Reports Server (NTRS)

    Stitzel, Joel D.; Bowlin, Gary L.; Mansfield, Kevin; Wnek, Gary E.; Simpson, David G.

    2000-01-01

    Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. Specific attention is given here to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options. Of particular interest is the ability to generate polymer fibers of sub-micron dimensions using electrospinning, down to about 0.05 microns (50 nm), a size range that has been traditionally difficult to access. In our work, poly(lactic-co-glycolic acid), PLA/PGA, poly(lactic acid) PLA, and poly(ethylene-co-vinylacetate) (PEVA) have been deposited from solutions in methylene chloride or chloroform by electrospraying or electrospinning to afford morphologically tailored materials for tissue engineering and related applications. Low solution concentrations tend to favor electrostatic spraying ('electro-aerosolization') while higher concentrations lead to spinning on fibrous mats. Preliminary observations of muscle cell growth on PLA electrospun mats are reported.

  9. Electroactive self-doped poly(amic acid) with oligoaniline and sulfonic acid groups: synthesis and electrochemical properties.

    PubMed

    Chi, Maoqiang; Wang, Shutao; Liang, Yuan; Chao, Danming; Wang, Ce

    2014-06-01

    A novel poly(amic acid) with pendant aniline tetramer and sulfonic acid groups (ESPAA) was synthesized by ternary polymerization and characterized by Fourier-transform infrared spectra, ((1))H NMR and gel permeation chromatography. The polymer showed good thermal stability and excellent solubility in the common organic solvents. The electrochemical properties were investigated carefully on a CHI 660A Electrochemical Workstation. The polymer displayed good electroactivity in acid, neutral and even in alkaline solutions (pH=1-10) due to the self-doping effect between aniline tetramer and sulfonic/carboxylic acid groups. It also exhibited satisfactory electrochromic performance with high contrast value, acceptable coloration efficiency and fast switching time in the range of pH=1-9. PMID:24703661

  10. Poly(isophthalic acid)(ethylene oxide) as a Macromolecular Modulator for Metal-Organic Polyhedra.

    PubMed

    Chen, Teng-Hao; Wang, Le; Trueblood, Jonathan V; Grassian, Vicki H; Cohen, Seth M

    2016-08-01

    A new strategy was developed by using a polymer ligand, poly(isophthalic acid)(ethylene oxide), to modulate the growth of metal-organic polyhedra (MOP) crystals. This macromolecular modulator can effectively control the crystal habit of several different Cu24L24 (L = isophthalic acid derivatives) MOPs. The polymer also directed the formation of MOP structures under reaction conditions that only produce metal-organic frameworks in the absence of modulator. Moreover, the polymer also enabled the deposition of MOP crystals on glass surfaces. This macromolecular modulator strategy provides an innovative approach to control the morphology and assembly of MOP particles. PMID:27400759

  11. Bioinspired bioadhesive polymers: dopa-modified poly(acrylic acid) derivatives.

    PubMed

    Laulicht, Bryan; Mancini, Alexis; Geman, Nathanael; Cho, Daniel; Estrellas, Kenneth; Furtado, Stacia; Hopson, Russell; Tripathi, Anubhav; Mathiowitz, Edith

    2012-11-01

    The one-step synthesis and characterization of novel bioinspired bioadhesive polymers that contain Dopa, implicated in the extremely adhesive byssal fibers of certain gastropods, is reported. The novel polymers consist of combinations of either of two polyanhydride backbones and one of three amino acids, phenylalanine, tyrosine, or Dopa, grafted as side chains. Dopa-grafted hydrophobic backbone polymers exhibit as much as 2.5 × the fracture strength and 2.8 × the tensile work of bioadhesion of a commercially available poly(acrylic acid) derivative as tested on live, excised, rat intestinal tissue. PMID:23008096

  12. Preparation and evaluation of lysozyme-loaded nanoparticles coated with poly-γ-glutamic acid and chitosan.

    PubMed

    Liu, Yong; Sun, Yan; Xu, Yaoxing; Feng, Hai; Fu, Sida; Tang, Jiangwu; Liu, Wei; Sun, Dongchang; Jiang, Hua; Xu, Shaochun

    2013-08-01

    To improve the application of lysozymes, methods for coating lysozymes with poly-γ-glutamic acid and chitosan were studied. Several lysozyme-loaded chitosan/poly-γ-glutamic acid composite nanosystems for loading and controlling the release of lysozymes were established. The lysozyme loading content and efficiency of the different systems were examined. The antibacterial activity of the composite nanoparticles was also investigated. Results showed that when the lysozymes were coated with poly-γ-glutamic acid and further rewrapped with chitosan, smooth spherical composite nanoparticles were obtained; the loading efficiency and loading content reached 76% and 40%, respectively. The lysozyme release in vitro was slow and presented a two-stage programmed release. Antibacterial testing in vitro indicated that lysozyme-loaded nanoparticles coated with poly-γ-glutamic acid/chitosan had outstanding antibacterial activity. An obvious assembly of bacterial cells and composite nanoparticles was observed during co-incubation. Therefore, the poly-γ-glutamic acid/chitosan composite coating broadened the antibacterial spectrum of the composite lysozyme nanoreagent, and presented satisfactory antibacterial effect. The lysozyme-loaded chitosan/poly-γ-glutamic acid nanocoating system established in this research could provide reference for coating and controlled releasing of alkaline proteins. PMID:23628585

  13. Electrospun composite scaffolds containing poly(octanediol-co-citrate) for cardiac tissue engineering.

    PubMed

    Prabhakaran, Molamma P; Nair, A Sreekumaran; Kai, Dan; Ramakrishna, Seeram

    2012-07-01

    A biocompatible and elastomeric nanofibrous scaffold is electrospun from a blend of poly(1,8-octanediol-co-citrate) [POC] and poly(L-lactic acid) -co-poly-(3-caprolactone) [PLCL] for application as a bioengineered patch for cardiac tissue engineering. The characterization of the scaffolds was carried out by Fourier transform infra red spectroscopy, scanning electron microscopy (SEM), and tensile measurement. The mechanical properties of the scaffolds are studied with regard to the percentage of POC incorporated with PLCL and the results of the study showed that the mechanical property and degradation behavior of the composites can be tuned with respect to the concentration of POC blended with PLCL. The composite scaffolds with POC: PLCL weight ratio of 40:60 [POC/PLCL4060] was found to have a tensile strength of 1.04 ± 0.11 MPa and Young's Modulus of 0.51 ± 0.10 MPa, comparable to the native cardiac tissue. The proliferation of cardiac myoblast cells on the electrospun POC/PLCL scaffolds was found to increase from Days 2 to 8, with the increasing concentration of POC in the composite. The morphology and cytoskeletal observation of the cells also demonstrated the biocompatibility of the POC containing scaffolds. Electrospun POC/PLCL4060 nanofibers are promising elastomeric substrates that might provide the necessary mechanical cues to cardiac muscle cells for regeneration of the heart. PMID:22328272

  14. Development of anti-scale poly(aspartic acid-citric acid) dual polymer systems for water treatment.

    PubMed

    Nayunigari, Mithil Kumar; Gupta, Sanjay Kumar; Kokkarachedu, Varaprasad; Kanny, K; Bux, F

    2014-01-01

    The formation of calcium sulphate and calcium carbonate scale poses major problems in heat exchangers and water cooling systems, thereby affecting the performance of these types of equipment. In order to inhibit these scale formations, new types of biodegradable water soluble single polymer and dual poly(aspartic acid-citric acid) polymers were developed and tested. The effectiveness of single polymer and four different compositions of poly aspartic acid and citric acid dual polymer systems as scale inhibitors were evaluated. Details of the synthesis, thermal stability, scale inhibition and the morphological characterization of single and dual polymers are presented in this scientific paper. It was found that the calcium sulphate scale inhibition rate was in the range 76.06-91.45%, while the calcium carbonate scale inhibition rate observed was in the range 23.37-30.0% at 65-70 °C. The finding suggests that the water soluble dual polymers are very effective in sulphate scale inhibition in comparison of calcium carbonate scale inhibition. PMID:25189837

  15. Poly(dopamine) coating of 3D printed poly(lactic acid) scaffolds for bone tissue engineering.

    PubMed

    Kao, Chia-Tze; Lin, Chi-Chang; Chen, Yi-Wen; Yeh, Chia-Hung; Fang, Hsin-Yuan; Shie, Ming-You

    2015-11-01

    3D printing is a versatile technique to generate large quantities of a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized 3D printed poly(lactic acid) (PLA) scaffolds and use a mussel-inspired surface coating to regulate cell adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared PLA 3D scaffolds coated with polydopamine (PDA). The chemical composition and surface properties of PDA/PLA were characterized by XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation, and cell cycle of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. In addition, the collagen I secreted from cells was increased and promoted cell attachment and cell cycle progression were depended on the PDA content. In osteogenesis assay, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on pure PLA scaffolds. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenic differentiation. Our results demonstrate that the bio-inspired coating synthetic PLA polymer can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to direct the specific responses of hADSCs. PMID:26249577

  16. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats.

    PubMed

    Lin, Chi-Chang; Fu, Shu-Juan

    2016-01-01

    Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs. PMID:26478309

  17. Fed-batch production of poly-3-hydroxydecanoate from decanoic acid.

    PubMed

    Gao, Jie; Ramsay, Juliana A; Ramsay, Bruce A

    2016-01-20

    Decanoic acid is an ideal substrate for the synthesis of medium-chain-length poly-3-hydroxyalkanoate (MCL-PHA), but its use for this purpose has only previously been studied in shake-flasks likely due to its surfactant properties, low aqueous solubility and high melting temperature. A fed-batch fermentation process was developed for the production of MCL-PHA from decanoic acid using Pseudomonas putida KT2440. Decanoic acid was kept in liquid form by heating or by mixing with acetic acid to prevent crystallization. Different ratios of decanoic acid:acetic acid:glucose (DA:AA:G) were fed to produce a specific growth rate of 0.15 h(-1). This method produced a maximum of 39 g L(-1) dry biomass containing 67% MCL-PHA when the DA:AA:G ratio was 5:1:4. However, a declining growth rate occurred in the late stage of fermentation, resulting in decanoic acid accumulation in the bioreactor leading to foaming. The duration of MCL-PHA production was extended by shifting from exponential to linear feeding before accumulation of decanoic acid. This resulted in 75 g L(-1) biomass containing 74% PHA and an overall PHA productivity of 1.16 g L(-1)h(-1) with the production of each gram of PHA requiring only 1.16 g of decanoic acid. The final PHA composition (on a molar basis) was 78% 3-hydroxydecanoate, 11% 3-hydroxyoctanoate and 11% 3-hydroxyhexanoate. PMID:26689481

  18. Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

    PubMed

    Hiraishi, Tomohiro

    2016-02-01

    Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2. PMID:26695157

  19. pH-Triggered release from surface-modified poly(lactic-co-glycolic acid) nanoparticles

    PubMed Central

    Häuser, Manuel; Langer, Klaus

    2015-01-01

    Summary Nanoparticles (NP) of poly(lactic-co-glycolic acid) (PLGA) represent a promising biodegradable drug delivery system. We suggest here a two-step release system of PLGA nanoparticles with a pH-tunable polymeric shell, providing an initial pH-triggered step, releasing a membrane-toxic cationic compound. PLGA nanoparticles are coated by polyelectrolytes using the layer-by-layer self-assembly technique, employing poly(acrylic acid) (PAA) as a pH-sensitive component and poly(diallyldimethylammonium chloride) (PDADMAC) as the releasable polycation. The pH during multilayer deposition plays a major role and influences the titration curve of the layer system. The pH-tunability of PAA is intensively investigated with regard to the pH region, in which the particle system becomes uncharged. The isoelectric point can be shifted by employing suitable deposition pH values. The release is investigated by quantitative 1H NMR, yielding a pH-dependent release curve. A release of PDADMAC is initiated by a decrease of the pH value. The released amount of polymer, as quantified by 1H NMR analysis, clearly depends on the pH value and thus on the state of deprotonation of the pH-sensitive PAA layer. Subsequent incubation of the nanoparticles with high concentrations of sodium chloride shows no further release and thus demonstrates the pH-driven release to be quantitative. PMID:26885463

  20. Temperature and pH responsiveness of poly-(DMAA-co-unsaturated carboxylic acid) hydrogels synthesized by UV-irradiation

    NASA Astrophysics Data System (ADS)

    Kakinoki, Sachiro; Kaetsu, Isao; Nakayama, Masashi; Sutani, Kouichi; Uchida, Kumao; Yukutake, Kouji

    2003-07-01

    Stimuli-responsive polyampholyte hydrogels were synthesized by the copolymerization of dimethylaminoethyl methacrylate (DMAA) and acrylic acid (AAc) or itaconic acid (IAc) by UV-irradiation. Temperature and pH responsiveness of these hydrogels were studied. The temperature responsiveness of poly-(DMAA-co-AAc, IAc) hydrogels shown in change of water content became dull compared to that of DMAA homo-polymer hydrogel. The water content of the poly-(DMAA-co-AAc, IAc) hydrogels showed a minimum at pH 8, and increased in more acidic and alkaline regions. This fact can be attributed to the coexistence of anions and cations in the poly-(DMAA-co-AAc, IAc) hydrogels. The poly-(DMAA-co-AAc, IAc) hydrogels were polyampholyte having both temperature responsiveness and pH responsiveness.

  1. Inkjet deposition of itraconazole onto poly(glycolic acid) microneedle arrays.

    PubMed

    Boehm, Ryan D; Jaipan, Panupong; Skoog, Shelby A; Stafslien, Shane; VanderWal, Lyndsi; Narayan, Roger J

    2016-03-01

    Poly(glycolic acid) microneedle arrays were fabricated using a drawing lithography process; these arrays were modified with a drug release agent and an antifungal agent by piezoelectric inkjet printing. Coatings containing poly(methyl vinyl ether-co-maleic anhydride), a water-soluble drug release layer, and itraconazole (an antifungal agent), were applied to the microneedles by piezoelectric inkjet printing. Microscopic evaluation of the microneedles indicated that the modified microneedles contained the piezoelectric inkjet printing-deposited agents and that the surface coatings were released in porcine skin. Energy dispersive x-ray spectrometry aided in confirmation that the piezoelectric inkjet printing-deposited agents were successfully applied to the desired target areas of the microneedle surface. Fourier transform infrared spectroscopy was used to confirm the presence of the component materials in the piezoelectric inkjet printing-deposited material. Itraconazole-modified microneedle arrays incubated with agar plates containing Candida albicans cultures showed zones of growth inhibition. PMID:26869165

  2. Thermoplastic starch/polyester films: effects of extrusion process and poly (lactic acid) addition.

    PubMed

    Shirai, Marianne Ayumi; Olivato, Juliana Bonametti; Garcia, Patrícia Salomão; Müller, Carmen Maria Olivera; Grossmann, Maria Victória Eiras; Yamashita, Fabio

    2013-10-01

    Biodegradable films were produced using the blown extrusion method from blends that contained cassava thermoplastic starch (TPS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) with two different extrusion processes. The choice of extrusion process did not have a significant effect on the mechanical properties, water vapor permeability (WVP) or viscoelasticity of the films, but the addition of PLA decreased the elongation, blow-up ratio (BUR) and opacity and increased the elastic modulus, tensile strength and viscoelastic parameters of the films. The films with 20% PLA exhibited a lower WVP due to the hydrophobic nature of this polymer. Morphological analyses revealed the incompatibility between the polymers used. PMID:23910321

  3. Inhibition of Poly(ADP-Ribose) Polymerase by Nucleic Acid Metabolite 7-Methylguanine

    PubMed Central

    Nilov, D. K.; Tararov, V. I.; Kulikov, A. V.; Zakharenko, A. L.; Gushchina, I. V.; Mikhailov, S. N.; Lavrik, O. I.; Švedas, V. K.

    2016-01-01

    The ability of 7-methylguanine, a nucleic acid metabolite, to inhibit poly(ADP-ribose)polymerase-1 (PARP-1) and poly(ADP-ribose)polymerase-2 (PARP-2) has been identified in silico and studied experimentally. The amino group at position 2 and the methyl group at position 7 were shown to be important substituents for the efficient binding of purine derivatives to PARPs. The activity of both tested enzymes, PARP-1 and PARP-2, was suppressed by 7-methylguanine with IC50 values of 150 and 50 μM, respectively. At the PARP inhibitory concentration, 7-methylguanine itself was not cytotoxic, but it was able to accelerate apoptotic death of BRCA1-deficient breast cancer cells induced by cisplatin and doxorubicin, the widely used DNA-damaging chemotherapeutic agents. 7-Methylguanine possesses attractive predictable pharmacokinetics and an adverse-effect profile and may be considered as a new additive to chemotherapeutic treatment. PMID:27437145

  4. Needlelike and spherical polyelectrolyte complex nanoparticles of poly(l-lysine) and copolymers of maleic acid.

    PubMed

    Müller, M; Reihs, T; Ouyang, W

    2005-01-01

    We report on the bulk and surface properties of dispersions consisting of nonstoichiometric polyelectrolyte complex (PEC) nanoparticles. PEC nanoparticles were prepared by mixing poly(l-lysine) (PLL) or poly(diallyldimethylammonium chloride) (PDADMAC) with poly(maleic acid-co-alpha-methylstyrene) (PMA-MS) or poly(maleic acid-co-propylene) (PMA-P). The monomolar mixing ratio was n-/n+ = 0.6, and the concentration ranged from 1 to 6 mmol/L. Subsequent centrifugation enabled the separation of the excess polycation, resulting in a stable coacervate phase further used in the experiments. The bulk phase parameters turbidity and hydrodynamic radius (R(h)) of the PEC nanoparticles showed a linear dependence on the total polymer content independently of the mixed polyelectrolytes. This can be interpreted by the increased collision probability of the polyelectrolyte chains when the overlap concentration is approached or exceeded. Different morphologies of the cationic PEC nanoparticles, which were solution-cast onto Si supports, were obtained by atomic force microscopy (AFM). The combinations of PLL/PMA-MS and PDADMAC/PMA-MS revealed more or less hemispherical particle shapes, whereas that of PLL/PMA-P revealed an elongated needlelike particle shape. Circular dichroism and attenuated total reflection Fourier transform infrared (ATR-FTIR) measurements proved the alpha-helical conformation for the PEC PLL/PMA-P and the random coil conformation for the PEC PLL/PMA-MS. We conclude that stiff alpha-helical PLL induces anisotropic elongated PEC nanoparticles, whereas randomly coiled PLL forms isotropic spherical PEC nanoparticles. PMID:15620340

  5. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release.

    PubMed

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery. PMID:26351630

  6. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release

    PubMed Central

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery. PMID:26351630

  7. Poly(lactide-co-glycolide acid)/biphasic calcium phosphate composite coating on a porous scaffold to deliver simvastatin for bone tissue engineering.

    PubMed

    Sadiasa, Alexander; Kim, Min Sung; Lee, Byong Taek

    2013-09-01

    In this study, simvastatin (SIM) drug incorporated poly(D,L-lactic-co-glycolide) (PLGA)/biphasic calcium phosphate (BCP) composite material (SPB) was coated on the BCP/ZrO2 (SPB-BCP/ZrO2) scaffold to enhance the mechanical and bioactive properties of the BCP/ZrO2 scaffold for bone engineering applications. The composite coating was prepared by combining different ratios of PLGA and BCP (1:2, 1:1, 2:1). After completion of the coating process, the compressive strength of the scaffolds was shown to increase with an increase in PLGA concentration from 8.5 ± 0.52 MPa for the SPB1-BCP/ZrO2 (1:2) to 11 ± 0.65 MPa for SPB3-BCP/ZrO2 (2:1) scaffolds when PLGA concentration was increased. Furthermore, the increase of PLGA in the coating composition corresponds to a decrease in porosity, degradation rate and weight loss of the scaffolds after 4 weeks. SIM release study demonstrated sustained release of the drug for the three kinds of scaffolds with improved biocompatibility. The increase of PLGA concentration also resulted in a lower release rate of SIM. Thus, the lower release rate of SIM brought upon by the increase of PLGA concentration further enhanced the performance of the scaffold in vitro making it a promising approach in the field of bone tissue regeneration. PMID:23815378

  8. Radiation synthesis of superabsorbent poly(acrylic acid)-carrageenan hydrogels

    NASA Astrophysics Data System (ADS)

    Francis, Sanju; Kumar, Manmohan; Varshney, Lalit

    2004-04-01

    A series of superabsorbent hydrogels were prepared from carrageenan and partially neutralized acrylic acid by gamma irradiation at room temperature. The gel fraction, swelling kinetics and the equilibrium degree of swelling (EDS) of the hydrogels were studied. It was found that the incorporation of even 1% carrageenan (sodium salt) increases the EDS of the hydrogels from ˜320 to ˜800 g/g. Thermal analysis were carried out to determine the amount of free water and bound water in the hydrogels. Under optimum conditions, poly(acrylic acid)-carrageenan hydrogels with high gel fraction (˜80%) and very high EDS (˜800 g/g) were prepared gamma radiolytically from aqueous solution containing 15% partially neutralized acrylic acid and 1-5% carrageenan. The hydrogels were also found to be sensitive to the pH and the ionic strength of the medium.

  9. Thermal-induced conversion of maleic and fumaric acid anion radicals in poly(methyl methacrylate)

    SciTech Connect

    Torikai, A.; Fukumoto, M.

    1980-04-01

    Thermal-induced conversion of maleic and fumaric acid anion radicals produced by ..gamma.. irradiation at 77/sup 0/K in poly(methyl methacrylate) (PMMA) was studied by electron spin resonance (ESR) and optical absorption spectroscopic measurements. The ESR spectra of these acid anion radicals change into two-line spectra with a line separation of ca. 10 G by thermal annealing. This spectrum is assigned to a protonated radical of each acid anion radical. Anion radicals of the solutes are relatively stable below the ..gamma.. transition point of PMMA and the conversion reaction takes place near this point. This means that the molecular motion of matrix molecule affects the radical conversion reaction.

  10. Chitosan-poly(acrylic) acid polyionic complex: in vivo study to demonstrate prolonged gastric retention.

    PubMed

    Torrado, Susana; Prada, Pablo; de la Torre, Paloma M; Torrado, Santiago

    2004-02-01

    The aim of this study was to develop a chitosan-poly(acrylic) acid based controlled drug release system for gastric antibiotic delivery. Different mixtures of amoxicillin (A), chitosan (CS), and poly(acrylic) acid (PAA) were employed to obtain these polyionic complexes. A non-invasive method was employed for determining the gastric residence time of the formulations. It was studied the swelling behavior and drug release from these complexes. Gastric emptying rate study was performed by means of the [13C]octanoic acid breath test. The gastric emptying rates of two different formulations (conventional and gastric retentive system) were studied. Swelling studies indicated that the extent of swelling was greater in the polyionic complexes than in the single chitosan formulations. The amoxicillin diffusion from the hydrogels was controlled by the polymer/drug interaction. The property of these complexes to control the solute diffusion depends on the network mesh size, which is a significant factor in the overall behavior of the hydrogels. The gastric half-emptying time of the polyionic complex was significantly delayed compared to the reference formulation, showing mean values of 164.32+/-26.72 and 65.06+/-11.50min, respectively (P<0.01). The results of this study suggest that, these polyionic complexes are good systems for specific gastric drug delivery. PMID:14609680

  11. Au nanoparticles/poly(caffeic acid) composite modified glassy carbon electrode for voltammetric determination of acetaminophen.

    PubMed

    Li, Tianbao; Xu, Juan; Zhao, Lei; Shen, Shaofei; Yuan, Maosen; Liu, Wenming; Tu, Qin; Yu, Ruijin; Wang, Jinyi

    2016-10-01

    An Au nanoparticles/poly(caffeic acid) (AuNPs/PCA) composite modified glassy carbon (GC) electrode was prepared by successively potentiostatic technique in pH 7.4 phosphate buffer solution containing 0.02mM caffeic acid and 1.0mM HAuCl4. Electrochemical characterization of the AuNPs/PCA-GC electrode was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The electrochemical behavior of acetaminophen (AP) at the AuNPs/PCA-GC electrode was also studied by cyclic voltammetry. Compared with bare GC and poly(caffeic acid) modified GC electrode, the AuNPs/PCA-GC electrode was exhibited excellent electrocatalytic activity toward the oxidation of AP. The plot of catalytic current versus AP concentration showed two linear segments in the concentration ranges 0.2-20µM and 50-1000µM. The detection limit of 14 nM was obtained by using the first range of the calibration plot. The AuNPs/PCA-GC electrode has been successfully applied and validated by analyzing AP in blood, urine and pharmaceutical samples. PMID:27474318

  12. Bifurcated hydrogen bonds stabilize fibrils of poly(L-glutamic) acid.

    PubMed

    Fulara, Aleksandra; Dzwolak, Wojciech

    2010-06-24

    Model fibrillating homopolypeptides have been providing many insightful analogies to the clinically important phenomena of protein misfolding and amyloidogenesis. Here we show that the beta(2) structural variant of poly(l-glutamic) acid forms fibrils with an amyloid-like morphology, ability to enhance fluorescence of thioflavin T, and seeding properties. The beta(2) fibrils are formed upon heating of aqueous solutions of alpha-helical poly(l-glutamic) acid, which leads to a significant increase of pD (pH) of unbuffered samples and a concomitant precipitation of fibrils with unusual infrared traits: amide I' band being dramatically red-shifted to 1596 cm(-1), and the -COOD stretching band split into two peaks around 1730 and 1719 cm(-1). We are proposing that formation of three-center hydrogen bonds involving bifurcated peptide carbonyl acceptors (>C=O) and main chains' NH, as well as side chains' -COOH proton donors is likely to underlie the observed infrared characteristics of beta(2) fibrils. Such bonds provide additional conformational constraints in a tightly packed environment around glutamate side chains resulting in the decreased overall acidity of the polypeptide. The presence of bifurcated hydrogen bonds in amyloid fibrils may be an overlooked factor in fibrils' robustness, thermodynamic stability and the ability to propagate their own growth. PMID:20509699

  13. Acrylic-acid-functionalized PolyHIPE scaffolds for use in 3D cell culture.

    PubMed

    Hayward, Adam S; Sano, Naoko; Przyborski, Stefan A; Cameron, Neil R

    2013-12-01

    This study describes the development of a functional porous polymer for use as a scaffold to support 3D hepatocyte culture. A high internal phase emulsion (HIPE) is prepared containing the monomers styrene (STY), divinylbenzene (DVB), and 2-ethylhexyl acrylate (EHA) in the external oil phase and the monomer acrylic acid (Aa) in the internal aqueous phase. Upon thermal polymerization with azobisisobutyronitrile (AIBN), the resulting porous polymer (polyHIPE) is found to have an open-cell morphology and a porosity of 89%, both suitable characteristics for 3D cell scaffold applications. X-ray photo-electron spectroscopy reveals that the polyHIPE surface contained 7.5% carboxylic acid functionality, providing a useful substrate for subsequent surface modifications and bio-conjugations. Initial bio-compatibility assessments with human hepatocytes show that the acid functionality does not have any detrimental effect on cell adhesion. It is therefore believed that this material can be a useful precursor scaffold towards 3D substrates that offer tailored surface functionality for enhanced cell adhesion. PMID:24243821

  14. Self-assembly of poly(o-methoxyaniline) hollow nanospheres from a polymeric acid solution

    NASA Astrophysics Data System (ADS)

    Sui, Jing; Zhang, Lijuan; Peng, Hui; Travas-Sejdic, Jadranka; Kilmartin, Paul A.

    2009-10-01

    Self-assembled poly(o-methoxyaniline) (POMA) hollow nanospheres were prepared in a solution of poly(methyl vinyl ether-alt-maleic acid) (PMVEA) by oxidative polymerization using ammonium persulfate as the oxidant. The weight ratio of PMVEA to o-methoxyaniline in the solution had a significant effect on the morphology of the poly(o-methoxyaniline) nanospheres as determined by scanning electron microscopy. The diameter of the hollow nanospheres decreased from 440 to 210 nm with an increase in the PMVEA concentration from 1% to 5%. Freeze-fracture transmission electron microscopy results showed the presence of spherical micelles composed of PMVEA/ o-methoxyaniline prior to polymerization, which also decreased in size as more PMVEA was added to the solution, and can act as soft templates for the formation of the hollow POMA nanospheres. The POMA/PMVEA hollow nanospheres were characterized by means of Fourier transform infrared, UV-visible, x-ray photoelectron spectroscopy, elemental analysis and conductivity measurements.

  15. Physiology and molecular genetics of poly(beta-hydroxy-alkanoic acid) synthesis in Alcaligenes eutrophus.

    PubMed

    Steinbüchel, A; Schlegel, H G

    1991-03-01

    The Alcaligenes eutrophus genes for beta-ketothiolase, NADPH-dependent acetoacetyl-CoA reductase and poly(beta-hydroxybutyric acid) synthase (PHB synthase) which comprise the three-step PHB-biosynthetic pathway, were cloned. Molecular studies revealed that these genes are organized in a single operon. The A. eutrophus PHB-biosynthetic genes are readily expressed in other bacteria, and DNA fragments harbouring the operon can be used as a cartridge to confer to other bacteria the ability to synthesize PHB from acetyl-CoA. The biochemical and physiological capabilities of A. eutrophus for the synthesis of a wide variety of polyhydroxyalkanoates are discussed. PMID:2046547

  16. Influence of poly(aminoquinone) on corrosion inhibition of iron in acid media

    NASA Astrophysics Data System (ADS)

    Jeyaprabha, C.; Sathiyanarayanan, S.; Phani, K. L. N.; Venkatachari, G.

    2005-11-01

    The inhibitor performance of chemically synthesized water soluble poly(aminoquinone) (PAQ) on iron corrosion in 0.5 M sulphuric acid was studied in relation to inhibitor concentration using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. On comparing the inhibition performance of PAQ with that of the monomer o-phenylenediamine (OPD), the OPD gave an efficiency of 80% for 1000 ppm while it was 90% for 100 ppm of PAQ. PAQ was found to be a mixed inhibitor. Besides, PAQ was able to improve the passivation tendency of iron in 0.5 M H 2SO 4 markedly.

  17. Spectroscopic characterization of genetically modified flax fibres enhanced with poly-3-hydroxybutyric acid

    NASA Astrophysics Data System (ADS)

    Wróbel-Kwiatkowska, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

    2009-02-01

    Genetically modified flax fibres, derived from transgenic flax with expression of three bacterial genes necessary for synthesis of poly-3-hydroxybutyric acid (PHB), have been analysed. These transgenic flaxes, enhanced with different amount of the PHB, have been studied by FT-IR spectroscopy. The integral intensities of the IR bands have been used for estimation of the chemical content of the normal and transgenic flaxes as well as the differences between the natural and genetically modified flax fibres. The spectroscopic data were compared to those obtained from chemical analysis of flax fibres.

  18. Low-velocity impact behavior of woven jute/poly(lactic acid) composites

    NASA Astrophysics Data System (ADS)

    Russo, Pietro; Simeoli, Giorgio; Papa, Ilaria; Acierno, Domenico; Lopresto, Valentina; Langella, Antonio

    2016-05-01

    Biocomposite laminates based on poly(lactic acid) (PLA) and woven jute fabric were obtained by film stacking and compression molding techniques. Sample laminates were systematically characterized by impact tests with a falling dart at impact energies equal to 5, 10 and 20 J. Tests showed that, investigated PLA/jute fabric plates suffer only barely visible damages at the first two levels of impact energy while they result to be perforated at 20 J as highlighted by photographic images taken on low and back side of impacted surfaces.

  19. Poly Lactic-co-Glycolic Acid (PLGA) as Biodegradable Controlled Drug Delivery Carrier

    PubMed Central

    Makadia, Hirenkumar K.; Siegel, Steven J.

    2011-01-01

    In past two decades poly lactic-co-glycolic acid (PLGA) has been among the most attractive polymeric candidates used to fabricate devices for drug delivery and tissue engineering applications. PLGA is biocompatible and biodegradable, exhibits a wide range of erosion times, has tunable mechanical properties and most importantly, is a FDA approved polymer. In particular, PLGA has been extensively studied for the development of devices for controlled delivery of small molecule drugs, proteins and other macromolecules in commercial use and in research. This manuscript describes the various fabrication techniques for these devices and the factors affecting their degradation and drug release. PMID:22577513

  20. Novel 4-Arm Poly(Ethylene Glycol)-Block-Poly(Anhydride-Esters) Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    PubMed Central

    Shen, Yuanyuan; Li, Min; Xu, Xiaofen; Li, Mingna; Guo, Shengrong; Huang, Shengtang

    2013-01-01

    A novel 4-arm poly(ethylene glycol)-block-poly(anhydride-esters) amphiphilic copolymer (4-arm PEG-b-PAE) was synthesized by esterization of 4-arm poly(ethylene glycol) and poly(anhydride-esters) which was obtained by melt polycondensation of α-, ω-acetic anhydride terminated poly(L-lactic acid). The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38 μg/mL. The curcumin-loaded 4-arm PEG-b-PAE micelles were prepared by a solid dispersion method and the drug loading content and encapsulation efficiency of the micelles were 7.0% and 85.2%, respectively. The curcumin-loaded micelles were spherical with a hydrodynamic diameter of 151.9 nm. Curcumin was encapsulated within 4-arm PEG-b-PAE micelles amorphously and released from the micelles, faster in pH 5.0 than pH 7.4, presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. The hemolysis rate of the curcumin-loaded 4-arm PEG-b-PAE micelles was 3.18%, which was below 5%. The IC50 value of the curcumin-loaded micelles against Hela cells was 10.21 μg/mL, lower than the one of free curcumin (25.90 μg/mL). The cellular uptake of the curcumin-loaded micelles in Hela cell increased in a time-dependent manner. The curcumin-loaded micelles could induce G2/M phase cell cycle arrest and apoptosis of Hela cells. PMID:23936812

  1. Glycerine and levulinic acid: renewable co-substrates for the fermentative synthesis of short-chain poly(hydroxyalkanoate) biopolymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Glycerine and levulinic acid were used alone and in combination for the fermentative synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V) biopolymers. Shake-flask cultures of Pseudomonas oleovorans NRRL B-14682 containing different glycerine:levulinic acid ratios (1%, w/v total carbon ...

  2. Electrospinning of Polyaniline/Poly(Lactic Acid) Ultrathin Fibers: Process and Statistical Modeling using a Non-Gaussian Approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fibers of poly(lactic acid) (PLA) blended with p-toluenesulfonic acid-doped polyaniline, PAni.TSA, were obtained by lectrospinning, following a factorial design which was used mainly to study the effect of four process parameters (PLA solution concentration, PAni solution concentration, applied volt...

  3. Poly(adenylic acid) in small amounts, free or covalently linked to substrate, protects RNA from hydrolysis by ribonuclease.

    PubMed Central

    Karpetsky, T P; Shriver, K K; Levy, C C

    1981-01-01

    Short lengths (18 residues) of poly(A), covalently linked to the 3'-termini of Escherichia coli 5 S rRNA, induce powerful inhibitions (38-87%) of the activities of RNAases (ribonucleases) from Citrobacter sp., Enterobacter sp., bovine pancreas, human spleen and human plasma. As the polypurine chain length is extended, enzyme activity declines. Furthermore, poly(A) sequences, present only on a small subpopulation of RNA, and accounting for less than 1% of total RNA, serve to protect all RNA, polyadenylated or not, from enzyme-catalysed degradation. The quantity of 3'-terminal adenylic acid residues, relative to the amount of substrate, determines enzyme activity. The exact distribution of a fixed amount of poly(A) residues on the 3'-termini of substrate molecules is unimportant in this respect. Comparison of the efficacies of inhibition of RNAase activity, by using linked poly(A) and similar quantities of free poly(A), revealed that although the free polypurine inhibits RNAase activity, covalent linkage of poly(A) to RNA is more advantageous to the stability of an RNA substrate. However, the ratio of inhibited activities obtained by using linked or free poly(A) may change considerably with alterations in either substrate concentration or polyadenylic acid segment length. PMID:6171250

  4. Poly(2-thiophen-3-yl-malonic acid), a polythiophene with two carboxylic acids per repeating unit.

    PubMed

    Bertran, Oscar; Armelin, Elaine; Estrany, Francesc; Gomes, Alex; Torras, Juan; Alemán, Carlos

    2010-05-20

    A new substituted polythiophene derivative bearing malonic acid, poly(2-thiophen-3-yl-malonic acid), has been prepared and characterized using a strategy that combines both experimental and theoretical methodologies. The chemical structure of this material has been investigated using FTIR and (1)H NMR, and its molecular conformation has been determined using quantum mechanical calculations. Interestingly, the arrangement of the inter-ring dihedral angles was found to depend on the ionization degree of the material, that is, on the pH, which has been found completely soluble in aqueous base solution. Thus, the preferred anti-gauche conformation changes to syn-gauche when the negatively charged carboxylate groups transforms into neutral carboxylic acid. UV-vis experiments and quantum mechanical calculations on model systems with a head-to-tail regiochemistry showed that the lowest pi-pi* transition energy is 2.25 and 2.39 eV for the negatively charged and the neutral polymer, respectively. These values are slightly larger than those previously reported for other polythiophenes with bulky polar side groups. The polymer presents a good thermal stability with a decomposition temperature above 215 degrees C and an electrical conductivity of 10(-5) S/cm, which is characteristic of semiconductor materials. Scanning electron microscopy micrographs showed that, after doping, the surface of this material displays regular distribution pores with irregular sizes. This surface suggests that poly(2-thiophen-3-yl-malonic acid) is a candidate for potential applications such as selective membranes for electrodialysis, wastewater treatment, or ion-selective membranes for biomedical uses. PMID:20411968

  5. Electrospun Poly(L-lactide)/Poly(ε-caprolactone) Blend Nanofibrous Scaffold: Characterization and Biocompatibility with Human Adipose-Derived Stem Cells

    PubMed Central

    Liao, Guiying; Peng, Ejun; Wu, Bolin; Wang, Yuxi; Zeng, Xiaoyong; Xie, Xiaolin

    2013-01-01

    The essence of tissue engineering is the fabrication of autologous cells or induced stem cells in naturally derived or synthetic scaffolds to form specific tissues. Polymer is thought as an appealing source of cell-seeded scaffold owing to the diversity of its physicochemical property and can be electrospun into nano-size to mimic natural structure. Poly (L-lactic acid) (PLLA) and poly (ε-caprolactone) (PCL) are both excellent aliphatic polyester with almost “opposite” characteristics. The controlling combination of PLLA and PCL provides varying properties and makes diverse applications. Compared with the copolymers of the same components, PLLA/PCL blend demonstrates its potential in regenerative medicine as a simple, efficient and scalable alternative. In this study, we electrospun PLLA/PCL blends of different weight ratios into nanofibrous scaffolds (NFS) and their properties were detected including morphology, porosity, degradation, ATR-FTIR analysis, stress-stain assay, and inflammatory reaction. To explore the biocompatibility of the NFS we synthesized, human adipose-derived stem cells (hASCs) were used to evaluate proliferation, attachment, viability and multi-lineage differentiation. In conclusion, the electrospun PLLA/PCL blend nanofibrous scaffold with the indicated weight ratios all supported hASCs well. However, the NFS of 1/1 weight ratio showed better properties and cellular responses in all assessments, implying it a biocompatible scaffold for tissue engineering. PMID:23990941

  6. Active targeting co-delivery system based on pH-sensitive methoxy-poly(ethylene glycol)2K-poly(ε-caprolactone)4K-poly(glutamic acid)1K for enhanced cancer therapy.

    PubMed

    Li, Nuannuan; Huang, Chunzhi; Luan, Yuxia; Song, Aixin; Song, Yunmei; Garg, Sanjay

    2016-06-15

    In this paper, we successfully synthesized folate-modified pH-sensitive copolymer methoxy-poly(ethylene glycol)2K-poly(ε-caprolactone)4K-poly(glutamic acid)1K (mPEG2K-PCL4K-PGA1K-FA), which could form the polymeric assembly in an aqueous solution, for co-delivering hydrophilic drugs doxorubicin hydrochloride (DOX) and verapamil hydrochloride (VER) (FA-poly(DOX+VER)). Since VER was an effective P-glycoprotein inhibitor, the combination of DOX and VER could reverse the multidrug resistance efficiently and enhance the therapeutic effect. Therefore, the inhibition ratios of MCF-7/ADR resistant cancer cell treated by FA-poly (DOX+VER) were almost more than 30% higher than those of FA-polyDOX after 48h and 72h. Furthermore, the conjugation of FA could lead the co-delivery systems actively targeting into the FA receptor over-expressing cancer cells in addition to the passive accumulation of the assembly in tumor tissues. Importantly, the prepared mPEG2K-PCL4K-PGA1K-FA assembly showed high pH-sensitive property, which made the drugs mostly released in tumor tissue (acid environment) than in physiological environment (neutral environment). In summary, the as-prepared co-delivery system FA-poly(DOX+VER) demonstrated a high efficiency in reversing the multidrug resistance and targeting FA receptor to improve the anticancer effect of DOX in MCF-7/ADR resistant cells. PMID:27016914

  7. Calculation of the hole mobilities of the three homopolynucleotides, poly(guanilic acid), poly(adenilic acid), and polythymidine in the presence of water and Na+ ions

    NASA Astrophysics Data System (ADS)

    Bende, Attila; Bogár, Ferenc; Beleznay, Ferenc; Ladik, János

    2008-12-01

    Recent high resolution x-ray diffraction experiments have determined the structure of nucleosomes. In it 147 base pair long DNA B superhelix is wrapped around the eight nucleohistone proteins. They have found that there are many hydrogen-bonds (H-bonds) between the negative sites phosphate ( PO4- ) groups DNA, and first of all there is the positively charged lysine and arginine side chains of the histones. This means that there is a non-negligible charge transfer from DNA to the proteins causing a hole current in DNA and an electronic one in the proteins. If the relative positions of the two macromolecules change due to some external disturbances, the DNA moves away from the protein and can be read. If this happens simultaneously at several nucleosomes and at many places in chromatin (built up from the nucleosomes), undesired genetic information becomes readable. This final end can cause the occurrence of oncoproteins at an undesired time point which most probably disturbs the self-regulation of a differentiated cell. The connection of these chain of events with the initiation of cancer is obvious. To look into the details of these events we have used the detailed band structures of the four homopolynucleotides in the presence of water and natrium ( Na+ ) ions calculated previously with the help of the ab initio Hartree-Fock crystal orbital method. We have found that in the case of three homopolynucleotides the width of their valence band is broad enough ( ˜10 times broader than the thermal energy at 300K ) for the application of the simple deformation potential approximation for transport calculations. With the help of this we have determined the hole mobilities at 300K and 180K of poly(guanilic acid), poly(adenilic acid), and polythimidine (polycytidine has a too narrow valence band for the application of the deformation potential method). The obtained mobilities are large enough to allow Bloch-type conduction in these systems. At the end of the paper we discuss

  8. A pH- and thermo-responsive poly(amino acid)-based drug delivery system.

    PubMed

    Liu, Na; Li, Bingqiang; Gong, Chu; Liu, Yuan; Wang, Yanming; Wu, Guolin

    2015-12-01

    A pH- and thermo-responsive poly(amino acid)-based amphiphilic copolymer was developed, functioning as a tumour targeting drug delivery system with good biocompatibility and biodegradability. To provide multi-stimuli sensitivity characteristics to the poly(amino acid)s, the polyaspartamide scaffold has been functionalized with N,N-diisopropylamide groups via aminolysis reaction of polysuccinimide. PEG chains have also been chemically grafted to the poly(amino acid) backbone through acid-labile hydrazone linkages, providing a removable shield for the poly(amino acid) based nanoparticles. Furthermore, doxorubicin was chemically linked to the copolymer chain via hydrazone bonds, acting as the hydrophobic moiety to drive the polymeric self-assembly. Free doxorubicin molecules could be encapsulated into the self-assembled nanoparticles via hydrophobic interactions and molecular π-π stacking. The results obtained show that the drug release can be triggered by the temperature with a significantly increased release being observed under acidic conditions. The cytotoxicity behaviour of the copolymers and drug-loaded nanoparticles was investigated in vitro at varying pH values and different temperatures. In doing so, superior characteristics concerning compatibility and anti-cancer activity could be observed. PMID:26454546

  9. Stabilization of polyion complex nanoparticles composed of poly(amino acid) using hydrophobic interactions.

    PubMed

    Akagi, Takami; Watanabe, Kazuki; Kim, Hyungjin; Akashi, Mitsuru

    2010-02-16

    We report the design and preparation of polyion complex (PIC) nanoparticles composed of anionic hydrophobically modified and cationic poly(amino acid) and the effect of hydrophobic interactions on the stability of these PIC nanoparticles under physiological conditions. We selected poly(gamma-glutamic acid) (gamma-PGA) as the biodegradable anionic polymer and poly(epsilon-lysine) (epsilon-PL) as the cationic polymer. Amphiphilic graft copolymers consisting of gamma-PGA and L-phenylalanine (L-Phe) as the hydrophobic side chain were synthesized by grafting L-Phe to gamma-PGA. The PIC nanoparticles were prepared by mixing gamma-PGA-graft-L-Phe (gamma-PGA-Phe) with epsilon-PL in phosphate buffered saline (PBS). The formation and stability of the PIC nanoparticles were investigated by dynamic light scattering (DLS) measurements. Monomodal anionic PIC nanoparticles were obtained using nonstoichiometric mixing ratios. When unmodified gamma-PGA was mixed with epsilon-PL in PBS, the formation of PIC nanoparticles was observed. However, within a few hours after the preparation, the PIC nanoparticles dissolved in the PBS. In contrast, gamma-PGA-Phe/epsilon-PL nanoparticles showed high stability for a prolonged period of time in PBS and over a wide range of pH values. The stability and size of the PIC nanoparticles depended on the gamma-PGA-Phe/epsilon-PL mixing ratio and the hydrophobicity of the gamma-PGA. The improved stability of the PIC nanoparticles was attributed to the formation of hydrophobic domains in the core of the nanoparticles. The fabrication of PIC nanoparticles using hydrophobic interactions was very useful for the stabilization of the nanoparticles. These results will provide a novel concept in the design of carrier systems composed of PIC. It is expected that the gamma-PGA-Phe/epsilon-PL nanoparticles will have great potential as multifunctional carriers for pharmaceutical and biomedical applications, such as drug and vaccine delivery systems. PMID:20017513

  10. Poly(lactic acid)/Carbon Nanotube Fibers as Novel Platforms for Glucose Biosensors.

    PubMed

    Oliveira, Juliano Elvis; Mattoso, Luiz Henrique Capparelli; Medeiros, Eliton Souto; Zucolotto, Valtencir

    2012-01-01

    The focus of this paper is the development and investigation of properties of new nanostructured architecture for biosensors applications. Highly porous nanocomposite fibers were developed for use as active materials in biosensors. The nanocomposites comprised poly(lactic acid)(PLA)/multi-walled carbon nanotube (MWCNT) fibers obtained via solution-blow spinning onto indium tin oxide (ITO) electrodes. The electrocatalytic properties of nanocomposite-modified ITO electrodes were investigated toward hydrogen peroxide (H2O2) detection. We investigated the effect of carbon nanotube concentration and the time deposition of fibers on the sensors properties, viz., sensitivity and limit of detection. Cyclic voltammetry experiments revealed that the nanocomposite-modified electrodes displayed enhanced activity in the electrochemical reduction of H2O2, which offers a number of attractive features to be explored in development of an amperometric biosensor. Glucose oxidase (GOD) was further immobilized by drop coating on an optimized ITO electrode covered by poly(lactic acid)/carbon nanotube nanofibrous mats. The optimum biosensor response was linear up to 800 mM of glucose with a sensitivity of 358 nA·mM-1 and a Michaelis-Menten constant (KM) of 4.3 mM. These results demonstrate that the solution blow spun nanocomposite fibers have great potential for application as amperometric biosensors due to their high surface to volume ratio, high porosity and permeability of the substrate. The latter features may significantly enhance the field of glucose biosensors. PMID:25585633

  11. Protein absorption and fouling on poly(acrylic acid)-graft-polypropylene microfiltration membrane

    NASA Astrophysics Data System (ADS)

    Liu, Yanjun; Ma, Huiying; Lv, Chunying; Yang, Jia; Fu, Xueqi

    2009-07-01

    A series of pH-sensitive poly (acrylic acid)-graft-polypropylene hollow fiber microfiltration membranes were prepared by UV-photo-irradiation. Bovine serum albumin (BSA) was chosen as the model protein to investigate its absorption and fouling behaviors on membranes. The results showed that the hydrophilicity of grafted membrane was improved by poly(acrylic acid) chains with parts of membrane pores blocked. The grafted membranes were markedly pH-dependent on the water permeability as pH was altered from 1 to 11. The zeta potential of grafted membranes calculated by streaming potential was negative in most pH range. Electrostatic interaction energy calculated by DLVO theory showed the electric interaction force between grafted membrane and BSA was attractive. With the rise of grafting degree, the electric attractive force between grafted membrane and BSA increased as pH=3 and decreased as pH=8, while it kept basically unchanged as pH=4.7. As a result, most serious fouling was observed as pH=4.7. Grafted membranes had a lower BSA absorption and better antifouling behavior as pH=8, while the opposite result was revealed as pH=3. In conclusion, the absorption and fouling behavior of BSA on membranes was pH-dependent due to the pH-dependence of membrane charge, and the conformation of BSA and grafting chains.

  12. Precipitation-Redispersion of Cerium Oxide Nanoparticles with Poly(acrylic acid): Toward Stable Dispersions

    SciTech Connect

    Sehgal,A.; Lalatonne, Y.; Berret, J.; Morvan, M.

    2005-01-01

    We exploit a precipitation-redispersion mechanism for complexation of short chain polyelectrolytes with cerium oxide nanoparticles to extend their stability ranges. As synthesized, cerium oxide sols at pH 1.4 consist of monodisperse cationic nanocrystalline particles having a hydrodynamic diameter of 10 nm and a molecular weight of 400 000 g mol{sup -1}. We show that short chain uncharged poly(acrylic acid) at low pH when added to a cerium oxide sols leads to macroscopic precipitation. As the pH is increased, the solution spontaneously redisperses into a clear solution of single particles with an anionic poly(acrylic acid) corona. The structure and dynamics of cerium oxide nanosols and their hybrid polymer-inorganic complexes in solution are investigated by static and dynamic light scattering, X-ray scattering, and chemical analysis. Quantitative analysis of the redispersed sol gives rise to an estimate of 40-50 polymer chains per particle for stable suspension. This amount represents 20% of the mass of the polymer-nanoparticle complexes. This complexation adds utility to the otherwise unstable cerium oxide dispersions by extending the range of stability of the sols in terms of pH, ionic strength, and concentration.

  13. Effect of Linker Structure on Salicylic Acid-Derived Poly(anhydride–esters)

    PubMed Central

    Prudencio, Almudena; Schmeltzer, Robert C.; Uhrich, Kathryn E.

    2013-01-01

    A series of salicylic acid-derived poly(anhydride–esters) were synthesized by melt polym erization methods, in which the structures of the molecule (“linker”) linking together the two salicylic acids were varied. To determine the relationship between the linker and the physical properties of the corresponding poly(anhydride–ester), several linkers were evaluated including linear aliphatic, aromatic, and aliphatic branched structures. For the linear aliphatic linkers, higher molecular weights were obtained with longer linear alkyl chains. The most sterically hindered linkers yielded lower molecular weight polymers. The thermal decomposition temperature increased with the alkyl chain length, but the glass transition temperature decreased, due to the enhanced flexibility of the polymer. The highest glass transition temperatures were obtained by using aromatic linkers as a result of increased π–π interactions. Water contact angles determined the relative hydrophobicity of the polymers, which correlated to hydrolytic degradation rates; i.e., the highest contact angle values yielded the slowest degrading polymers. PMID:23976793

  14. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    SciTech Connect

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  15. Post-polymerization modification of poly(L-glutamic acid) with D-(+)-glucosamine.

    PubMed

    Perdih, Peter; Cebašek, Sašo; Možir, Alenka; Zagar, Ema

    2014-01-01

    Carboxyl functional groups of poly(L-glutamic acid) (PGlu) were modified with a D-(+)-glucosamine (GlcN) by amidation using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) as a coupling reagent. The coupling reaction was performed in aqueous medium without protection of hydroxyl functional groups of D-(+)-glucosamine. Poly(L-glutamic acid) and GlcN functionalized polyglutamates (P(Glu-GlcN)) were thoroughly characterized by 1D and 2D NMR spectroscopy and SEC-MALS to gain detailed information on their structure, composition and molar mass characteristics. The results reveal successful functionalization with GlcN through the amide bond and also to a minor extent through ester bond formation in position 1 of GlcN. In addition, a ratio between the α- and β-form of glucosamine substituent coupled to polyglutamate repeating units as well as the content of residual dimethoxy triazinyl active ester moiety in the samples were evaluated. PMID:25438084

  16. High-molecular-weight polymers for protein crystallization: poly-γ-glutamic acid-based precipitants

    SciTech Connect

    Hu, Ting-Chou; Korczyńska, Justyna; Smith, David K.; Brzozowski, Andrzej Marek

    2008-09-01

    High-molecular-weight poly-γ-glutamic acid-based polymers have been synthesized, tested and adopted for protein crystallization. Protein crystallization has been revolutionized by the introduction of high-throughput technologies, which have led to a speeding up of the process while simultaneously reducing the amount of protein sample necessary. Nonetheless, the chemistry dimension of protein crystallization has remained relatively undeveloped. Most crystallization screens are based on the same set of precipitants. To address this shortcoming, the development of new protein precipitants based on poly-γ-glutamic acid (PGA) polymers with different molecular-weight ranges is reported here: PGA-LM (low molecular weight) of ∼400 kDa and PGA-HM (high molecular weight) of >1000 kDa. It is also demonstrated that protein precipitants can be expanded further to polymers with much higher molecular weight than those that are currently in use. Furthermore, the modification of PGA-like polymers by covalent attachments of glucosamine substantially improved their solubility without affecting their crystallization properties. Some preliminary PGA-based screens are presented here.

  17. Morphologies, mechanical properties and thermal stability of poly(lactic acid) toughened by precipitated barium sulfate

    NASA Astrophysics Data System (ADS)

    Yang, Jinian; Wang, Chuang; Shao, Kaiyun; Ding, Guoxin; Tao, Yulun; Zhu, Jinbo

    2015-11-01

    Poly(lactic acid) (PLA)-based composites were prepared by blending PLA with precipitated barium sulfate (BaSO4) modified with stearic acid. The morphologies, mechanical properties and thermal stability of samples with increased mass fraction of BaSO4 were investigated. Results showed that PLA was toughened and reinforced simultaneously by incorporation of precipitated BaSO4 particles. The highest impact toughness and elongation at break were both achieved at 15% BaSO4, while the elastic modulus increased monotonically with increasing BaSO4 loading. Little effect of BaSO4 on the thermal behavior of PLA was observed in the present case. However, the thermal stability of PLA/BaSO4 composites at high temperature was enhanced.

  18. Ag@poly(m-phenylenediamine) core-shell nanoparticles for highly selective, multiplex nucleic acid detection.

    PubMed

    Zhang, Yingwei; Wang, Lei; Tian, Jingqi; Li, Hailong; Luo, Yonglan; Sun, Xuping

    2011-03-15

    In this letter, we report on the one-step synthesis of Ag@poly(m-phenylenediamine) core-shell nanoparticles (APCSNPs), carried out by direct mixing of aqueous silver nitrate and m-phenylenediamine solutions at room temperature. We further demonstrate the use of APCSNP as a novel fluorescent sensing platform for nucleic acid detection. In this regard, the detection of DNA is accomplished in two steps. First, APCSNP absorbs and quenches the fluorescence of dye-labeled single-stranded DNA (ssDNA) as a probe. Second, hybridizing of the probe with its target produces a double-stranded DNA (dsDNA) that detaches from APCSNP, resulting in the recovery of dye fluorescence. It suggests that this sensing system has a high selectivity down to single-base mismatch, and the results exhibit good reproducibility. Furthermore, we also demonstrate its application for the multiplex detection of nucleic acid sequences. PMID:21302954

  19. Modification of silicon nitride slip properties by poly(acrylic acid)

    SciTech Connect

    Hackley, V.A.; Maglhan, S.G.

    1996-06-01

    Acrylic-acid based polyelectrolytes are used for dispersion and rheology control of ceramic powder slips. This study focuses on the Si{sub 3}N4/H{sub 2}O/poly(acrylic acid) (PAA) system, with the goal of improving our basic understanding of the mechanisms which may significantly affect slip properties during processing. A variety of experimental techniques were employed, including potentiometric titration, electroacoustic analysis, adsorption isotherms, and controlled-stress rheology. The slips exhibited complex behavior over a wide range of conditions in which solids concentration, PAA molecular weight and concentration, and pH were varied. Polymer charge and conformation were found to have significant impact on the flow properties. Pseudoplastic behavior was attributed to the presence of free polymer. The flow properties were also found to be highly pH dependent.

  20. Semiconductor nanoparticles in poly((2-dimethylamino)ethyl methacrylate-co-acrylic acid) co-polymers

    NASA Astrophysics Data System (ADS)

    Trandafilović, L. V.; Bibić, N.; Georges, M. K.; Blanuša, J.; Radhakrishnan, T.; Djoković, V.

    2013-11-01

    Nanostructured cadmium selenide (CdSe) and lead sulfide (PbS) semiconductors were prepared in a poly(2-(dimethylamino)ethyl methacrylate-co-acrylic acid) matrix. The obtained nanoparticles were characterized by using optical and structural methods. Co-polymers were synthesized in two different molar ratios of pDMAEMA:acrylic acid monomer units (1:2, 1:1). Transmission electron microscopy analysis confirmed the presence of nano-sized CdSe and PbS particles. In the case of CdSe, a shift of the onset of the optical absorption toward lower wavelengths was observed. X-ray diffraction analysis revealed that both CdSe and PbS nanoparticles have cubic crystal structure.

  1. Tacticity control in the synthesis of poly(lactic acid) polymer stars with dipentaerythritol cores.

    PubMed

    Shaver, Michael P; Cameron, Donald J A

    2010-12-13

    The synthesis of a family of polymer stars with arms of varied tacticities is discussed. The effect of polymer tacticity on the physical properties of these polymer stars is presented. Dipentaerythritol cores support six poly(lactic acid) (PLA) arms. Lewis acidic tin and aluminum catalysts control the polymerization to afford polymer stars of variable tacticity. The analysis of these polymers by NMR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and differential scanning calorimetry reveals the effects of tacticity control on the physical properties of the polymer stars. Preliminary decomposition studies suggest that the biodegradation profile of a polymer star may also be tuned by stereochemical control. This is the first systematic altering of tacticity in PLA polymer stars, showing that polymer tacticity can have a great impact on star properties. PMID:21033736

  2. ABS polymer electroless plating through a one-step poly(acrylic acid) covalent grafting.

    PubMed

    Garcia, Alexandre; Berthelot, Thomas; Viel, Pascal; Mesnage, Alice; Jégou, Pascale; Nekelson, Fabien; Roussel, Sébastien; Palacin, Serge

    2010-04-01

    A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate. PMID:20361751

  3. Galactosylated poly(ethyleneglycol)-lithocholic Acid selectively kills hepatoma cells, while sparing normal liver cells.

    PubMed

    Gankhuyag, Nomundelger; Singh, Bijay; Maharjan, Sushila; Choi, Yun-Jaie; Cho, Chong-Su; Cho, Myung-Haing

    2015-06-01

    Delivering drugs selectively to cancer cells but not to nearby normal cells is a major obstacle in drug therapy. In this study, lithocholic acid (LCA), a potent anti-cancer drug, is converted to two forms of poly(ethyleneglycol) (PEG) conjugates, viz., PEG-LCA (PL) and lactobionic acid (LBA) conjugated PEG-LCA (LPL). The latter form contains a galactose ligand in LBA to target the hepatocytes. Both forms are self-assembled to form nanoparticle formulation, and they have high potency than LCA to kill HepG2 cancer cells, sparing normal LO2 cells. Besides, LPL has high specificity to mouse liver cells in vivo. Western blot results confirm that the cell death is occurred through apoptosis induced by LPL nanoparticles. In conclusion, the induction of apoptosis and cell death is much more efficient with LPL nanoparticles than LCA molecules. PMID:25657071

  4. Preparation of silver-poly(acrylamide-co-methacrylic acid) composite microspheres with patterned surface structures.

    PubMed

    Xia, Huiyun; Zhang, Ying; Peng, Junxia; Fang, Yu; Gu, Zhongze

    2006-01-01

    Acrylamide (AM) and methacrylic acid (MAA) copolymer microgels were prepared by a reverse suspension polymerization technique. The microgels were used as templates for the preparation of silver-poly(acrylamide-co-methacrylic acid) [Ag-P(AM-co-MAA)] composite microspheres. The surface structures of the microspheres prepared in this way are characterized by zigzag-like structures. It was found that the composition of the microgels, the nature and dosage of surfactants, the quantity of the metal, and even the reduction methods employed have a significant effect upon the surface structures of the microspheres. X-ray diffraction analysis confirmed that Ag formed during the process is in a crystal state of a face-centered cubic structure. PMID:24058232

  5. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    NASA Astrophysics Data System (ADS)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

    2014-10-01

    In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  6. In vitro testing of thiolated poly(aspartic acid) from ophthalmic formulation aspects.

    PubMed

    Budai-Szű Cs, Mária; Horvát, Gabriella; Gyarmati, Benjámin; Szilágyi, Barnabás Áron; Szilágyi, András; Csihi, Tímea; Berkó, Szilvia; Szabó-Révész, Piroska; Mori, Michela; Sandri, Giuseppina; Bonferoni, Maria Cristina; Caramella, Carla; Csányi, Erzsébet

    2016-08-01

    Ocular drug delivery formulations must meet anatomical, biopharmaceutical, patient-driven and regulatory requirements. Mucoadhesive polymers can serve as a better alternative to currently available ophthalmic formulations by providing improved bioavailability. If all requirements are addressed, a polymeric formulation resembling the tear film of the eye might be the best solution. The optimum formulation must not have high osmotic activity, should provide appropriate surface tension, pH and refractive index, must be non-toxic and should be transparent and mucoadhesive. We would like to highlight the importance of in vitro polymer testing from a pharmaceutical aspect. We, therefore, carried out physical-chemical investigations to verify the suitability of certain systems for ophthalmic formulations. In this work, in situ gelling, mucoadhesive thiolated poly(aspartic acid)s were tested from ophthalmic formulation aspects. The results of preformulation measurements indicate that these polymers can be used as potential carriers in ophthalmic drug delivery. PMID:26556306

  7. Electron-beam induced RAFT-graft polymerization of poly(acrylic acid) onto PVDF

    NASA Astrophysics Data System (ADS)

    Grasselli, M.; Betz, N.

    2005-07-01

    This paper explores for the first time the post-radiation-induced-graft polymerization on solid substrate using reversible addition-fragmentation transfer (RAFT) mechanism. Radiation-induced graft polymerization onto polymers is a potentially interesting technique to create easily new materials from highly resistant polymers, e.g. surface graft polymerization of acrylic acid (AA) onto poly(vinylidene difluoride) (PVDF) improves its surface properties without losing its excellent mechanical properties. As a consequence of the radical nature of the polymerization processes it is difficult to control molecular weight of grafted chains, and therefore design and standardize the properties of the final product. RAFT polymerization is a suitable method to obtain monodisperse polymers. The ability of the RAFT agents to control the polymer chain length could be an interesting approach to improve the grafted polymers obtained by post-radiation-induced-graft polymerization technique. In this way, graft polymerization of AA onto electron-beam irradiated α-PVDF was performed using trithiocarbonic acid bis(1-phenylethyl) ester as a RAFT agent to control the radical polymerization. We studied several grafting parameters such as solvent, monomer concentration and grafting time in order to achieve a poly(acrylic acid) (PAA) layer onto PVDF surface. Acetic acid was found to be the best solvent for many reasons, as to drive graft polymerization mainly to the polymer surface, complete solubility and stability of all reactants. Hydrolysis of PAA chains was also studied in order to remove the trithiocarbonate functionality from the grafted polymer. A mild chemical condition was achieved in order to have thiol groups that were detected onto the modified PVDF by specific enzymatic reaction.

  8. Poly(acrylic acid)-grafted fluoropolymer films for highly sensitive fluorescent bioassays.

    PubMed

    Jung, Chan-Hee; Hwang, In-Tae; Kuk, In-Seol; Choi, Jae-Hak; Oh, Byung-Keun; Lee, Young-Moo

    2013-03-01

    In this study, a facile and effective method for the surface functionalization of inert fluoropolymer substrates using surface grafting was demonstrated for the preparation of a new platform for fluorescence-based bioassays. The surface of perfluorinated poly(ethylene-co-propylene) (FEP) films was functionalized using a 150 keV ion implantation, followed by the graft polymerization of acrylic acid, to generate a high density of carboxylic acid groups on the implanted surface. The resulting functionalized surface was investigated in terms of the surface density of carboxylic acid, wettability, chemical structure, surface morphology, and surface chemical composition. These results revealed that poly(acrylic acid) (PAA) was successfully grafted onto the implanted FEP surface and its relative amount depended on the fluence. To demonstrate the usefulness of this method for the fabrication of bioassays, the PAA-grafted FEP films were utilized for the immobilization of probe DNA for anthrax toxin, followed by hybridization with Cy3-labeled target DNA. Liver cancer-specific α-feto-protein (AFP) antigen was also immobilized on the PAA-grafted FEP films. Texas Red-labeled secondary antibody was reacted with AFP-specific primary antibody prebound to the AFP antigen using an immunoassay method. The results revealed that the fluorescence intensity clearly depended on the concentration of the target DNA hybridized to the probe DNA and the AFP antigen immobilized on the FEP films. The lowest detectable concentrations of the target DNA and the AFP antigen were 10 fg/mL and 10 pg/mL, respectively, with the FEP films prepared at a fluence of 3 × 10(14) ions/cm(2). PMID:23452270

  9. In vivo biocompatibility studies of poly( n-vinyl 2-pyrrolidone/itaconic acid) hydrogels synthesized by γ-rays

    NASA Astrophysics Data System (ADS)

    Özdemir, S.; Özdemir, E.; Tunca, R.; Hazıroǧlu, R.; Şen, M.; Kantoǧlu, Ö.; Güven, O.

    2003-08-01

    In this study, poly( n-vinyl 2-pyrrolidone/itaconic acid) hydrogels have been synthesized by γ-rays in different compositions and their biocompatibility have been investigated as in vivo and some biochemical parameters of mice serum and histology of their tissues have been examined. By these purposes, poly( n-vinyl 2-pyrrolidone/itaconic acid) (P(VP/IA)) hydrogels were implanted to hypersensitive mice (BALB/c). One and a half months after implantation, hydrogel implanted animals were sacrificed by ether anesthesia and the area hydrogel contacted with tissue was investigated by light microscope for histopathological identification of the tissue. Then the total immunoglobulin E (IgE) level was determined by ELISA. Differential white cell count was also made to better understanding of reaction between hydrogel and tissue. These poly( n-vinyl 2-pyrrolidone/itaconic acid) hydrogels can be directly used as biomedical materials.

  10. Electrochemistry of poly(vinylferrocene) modified electrodes in aqueous acidic media

    NASA Astrophysics Data System (ADS)

    Issa, Touma B.; Singh, Pritam; Baker, Murray V.

    A cyclic voltammetric study of the electrochemistry and chemical stability of the poly(vinylferrocene) (PVFc) redox couple, coated on a gold substrate, in aqueous solutions of H 2SO 4, HClO 4 and HCl was carried out. It was found that the anodic peak potential ( Epa) did not depend on the acid concentration in the range (1.0 × 10 -2 to 1.0 × 10 -7 mol L -1). However, the Epa values shifted linearly to less positive potentials when investigated in more concentrated acid solutions in the range 1-5 mol L -1. The slope of the Epa versus acid concentration graph was found to be in the order H 2SO 4 > HCl > HClO 4. In this regard PVFc behaved very similar to 1,1'-bis(11-mercaptoundecyl)ferrocene (Fc(C 11SH) 2) except for its chemical stability. In H 2SO 4 media the PVFc was found to be much less stable than 1,1'-Fc(C 11SH) 2. The dependence of Epa on acid concentration could be used to monitor state of charge of lead-acid batteries. However, for this application Fc(C 11SH) 2 would be a better choice because of its superior chemical stability.

  11. Poly-lactic acid synthesis for application in biomedical devices - a review.

    PubMed

    Lasprilla, Astrid J R; Martinez, Guillermo A R; Lunelli, Betânia H; Jardini, André L; Filho, Rubens Maciel

    2012-01-01

    Bioabsorbable polymers are considered a suitable alternative to the improvement and development of numerous applications in medicine. Poly-lactic acid (PLA,) is one of the most promising biopolymers due to the fact that the monomers may produced from non toxic renewable feedstock as well as is naturally occurring organic acid. Lactic acid can be made by fermentation of sugars obtained from renewable resources as such sugarcane. Therefore, PLA is an eco-friendly product with better features for use in the human body (nontoxicity). Lactic acid polymers can be synthesized by different processes so as to obtain products with an ample variety of chemical and mechanical properties. Due to their excellent biocompatibility and mechanical properties, PLA and their copolymers are becoming widely used in tissue engineering for function restoration of impaired tissues. In order to maximize the benefits of its use, it is necessary to understand the relationship between PLA material properties, the manufacturing process and the final product with desired characteristics. In this paper, the lactic acid production by fermentation and the polymer synthesis such biomaterial are reviewed. The paper intends to contribute to the critical knowledge and development of suitable use of PLA for biomedical applications. PMID:21756992

  12. Nucleating effect of exfoliated graphite nanoplatelets on poly(hydroxybutyrate) and poly(lactic acid) and their nanocomposites properties

    NASA Astrophysics Data System (ADS)

    Miloaga, Dana Gabriela

    Multifunctional polymer nanocomposites are attractive due to the multitude of properties that can be imparted to polymer matrices by the addition of small amounts of nanoparticles. Exfoliated graphite nanoplatelets (xGnP) represent a new nanosized reinforcing material that can lead to multifunctional polymer nanocomposites, and are a significantly less expensive alternative to other carbon nanomaterials (e.g. carbon nanotubes). The benefits of xGnP have been shown in nanocomposites made with several petroleum-derived thermoplastic polymers. Nanocomposites from biobased polymers and xGnP have not yet been investigated and are the object of this study. This research is directed at understanding the interactions between xGnP and two polyesters derived from renewable resources, poly(3-hydroxybutyrate) (PHB), and polylactic acid (PLA). PHB and PLA are both semicrystalline polymers. Their properties largely depend on the degree of crystallinity, crystallization rate, and on the size and number of crystallites formed. For faster crystallization, important especially for dynamic processing conditions, both polymers often require the addition of nucleation agents. xGnP is shown to act as a nucleating agent, and to impart higher strength, modulus, thermal and electrical conductivity to these polymer matrices as well. Specifically, the research conducted covers two main aspects of the nucleating effect of xGnP on PHB and PLA: the rate of overall crystallization from the melt as a function of the amount of xGnP, and the influence of xGnP on the morphology and properties of the nanocomposites. A kinetic study of the PHB/xGnP crystallization, employing a modified form of the Avrami equation, revealed that the presence of xGnP increased the PHB crystallization temperature, as well as the crystallization rates. Optical microscopy and atomic force microscopy investigations revealed the reduction in the size of PHB spherulites. Nanocomposite properties were studied for PLA

  13. Introduction of poly[(2-acryloyloxyethyl trimethyl ammonium chloride)-co-(acrylic acid)] branches onto starch for cotton warp sizing.

    PubMed

    Shen, Shiqi; Zhu, Zhifeng; Liu, Fengdan

    2016-03-15

    An attempt has been made to reveal the effect of amphoteric poly(2-acryloyloxyethyl trimethyl ammonium chloride-co-acrylic acid) [P(ATAC-co-AA)] branches grafted onto the backbones of starch upon the adhesion-to-cotton, film properties, and desizability of maize starch for cotton warp sizing. Starch-g-poly[(2-acryloyloxyethyl trimethyl ammonium chloride)-co-(acrylic acid) [S-g-P(ATAC-co-AA)] was prepared by the graft copolymerization of 2-acryloyloxyethyl trimethyl ammonium chloride (ATAC) and acrylic acid (AA) with acid-converted starch (ACS) in aqueous medium using Fe(2+)-H2O2 initiator. The adhesion was evaluated in term of bonding strength according to the FZ/T 15001-2008 whereas the film properties considered included tensile strength, work and percentage elongation at break. The evaluation was undertaken through the comparison of S-g-P(ATAC-co-AA) with ACS, starch-g-poly(acrylic acid), and starch-g-poly(2-acryloyloxyethyl trimethyl ammonium chloride). It was found that the amphoteric branch was able to significantly improve the adhesion and mitigate the brittleness of starch film. Zeta potential of cooked S-g-P(ATAC-co-AA) paste, depending on the mole ratio of ATAC to AA units on P(ATAC-co-AA) branches, had substantial effect on the adhesion and desizability. Increasing the mole ratio raised the potential, which favored the adhesion but disfavored the removal of S-g-P(ATAC-co-AA) from sized cotton warps. Electroneutral S-g-P(ATAC-co-AA) was superior to negatively grafted starch in adhesion and to positively grafted starch in desizability. Generally, it showed better sizing property than ACS, starch-g-poly(acrylic acid), and starch-g-poly(2-acryloyloxyethyl trimethyl ammonium chloride), and had potential in the application of cotton warp sizing. PMID:26794764

  14. Enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film by acid treatment for indium tin oxide-free organic solar cells

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Chiao; Huang, Chih-Kuo; Hung, Yu-Chieh; Chang, Mei-Ying

    2016-08-01

    An acid treatment is used in the enhancement of the conductivity of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin film, which is often used as the anode in organic solar cells. There are three types of acid treatment for PEDOT:PSS thin film: hydrochloric, sulfuric, and phosphoric acid treatments. In this study, we examine and compare these three ways with each other for differences in conductivity. Hydrochloric acid results in the highest conductivity enhancement, from 0.3 to 1109 S/cm. We also discuss the optical transmittance, conductivity, surface roughness, surface morphology, and stability, as well as the factors that can influence device efficiency. The devices are fabricated using an acid-treated PEDOT:PSS thin film as the anode. The highest power conversion efficiency was 1.32%, which is a large improvement over that of the unmodified organic solar cell (0.21%). It is comparable to that obtained when using indium tin oxide (ITO) as an electrode, ca. 1.46%.

  15. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax.

    PubMed

    Wróbel-Kwiatkowska, Magdalena; Zuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Maczka, Mirosław; Hanuza, Jerzy

    2009-07-15

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds. PMID:19328737

  16. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax

    NASA Astrophysics Data System (ADS)

    Wróbel-Kwiatkowska, Magdalena; Żuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

    2009-07-01

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds.

  17. Minimally invasive injectable short nanofibers of poly(glycerol sebacate) for cardiac tissue engineering.

    PubMed

    Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

    2012-09-28

    Myocardial tissue lacks the ability to appreciably regenerate itself following myocardial infarction (MI) which ultimately results in heart failure. Current therapies can only retard the progression of disease and hence tissue engineering strategies are required to facilitate the engineering of a suitable biomaterial to repair MI. The aim of this study was to investigate the in vitro properties of an injectable biomaterial for the regeneration of infarcted myocardium. Fabrication of core/shell fibers was by co-axial electrospinning, with poly(glycerol sebacate) (PGS) as core material and poly-L-lactic acid (PLLA) as shell material. The PLLA was removed by treatment of the PGS/PLLA core/shell fibers with DCM:hexane (2:1) to obtain PGS short fibers. These PGS short fibers offer the advantage of providing a minimally invasive injectable technique for the regeneration of infarcted myocardium. The scaffolds were characterized by SEM, FTIR and contact angle and cell-scaffold interactions using cardiomyocytes. The results showed that the cardiac marker proteins actinin, troponin, myosin heavy chain and connexin 43 were expressed more on short PGS fibers compared to PLLA nanofibers. We hypothesized that the injection of cells along with short PGS fibers would increase cell transplant retention and survival within the infarct, compared to the standard cell injection system. PMID:22947662

  18. Minimally invasive injectable short nanofibers of poly(glycerol sebacate) for cardiac tissue engineering

    NASA Astrophysics Data System (ADS)

    Ravichandran, Rajeswari; Reddy Venugopal, Jayarama; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

    2012-09-01

    Myocardial tissue lacks the ability to appreciably regenerate itself following myocardial infarction (MI) which ultimately results in heart failure. Current therapies can only retard the progression of disease and hence tissue engineering strategies are required to facilitate the engineering of a suitable biomaterial to repair MI. The aim of this study was to investigate the in vitro properties of an injectable biomaterial for the regeneration of infarcted myocardium. Fabrication of core/shell fibers was by co-axial electrospinning, with poly(glycerol sebacate) (PGS) as core material and poly-l-lactic acid (PLLA) as shell material. The PLLA was removed by treatment of the PGS/PLLA core/shell fibers with DCM:hexane (2:1) to obtain PGS short fibers. These PGS short fibers offer the advantage of providing a minimally invasive injectable technique for the regeneration of infarcted myocardium. The scaffolds were characterized by SEM, FTIR and contact angle and cell-scaffold interactions using cardiomyocytes. The results showed that the cardiac marker proteins actinin, troponin, myosin heavy chain and connexin 43 were expressed more on short PGS fibers compared to PLLA nanofibers. We hypothesized that the injection of cells along with short PGS fibers would increase cell transplant retention and survival within the infarct, compared to the standard cell injection system.

  19. Adsorption of (poly)maleic acid and an aquatic fulvic acid by geothite

    NASA Astrophysics Data System (ADS)

    Wang, Lili; Chin, Yu-Ping; Traina, Samuel J.

    1997-12-01

    The adsorption of Suwannee River fulvic acid (SRFA) and a synthetic organic polymer, polymaleic acid (PMA) by geothite was studied. The adsorption density of the sorbates decreased with increasing pH, and the data could best be described by the Langmuir adsorption equation. The number- and weight-averaged molecular weights, Mw and Mn, of the sorbates in the solution phase before and after adsorption by geothite were measured by high-pressure size exclusion chromatography. The observed decreases in the Mn and Mw of SRFA in the solution phase after adsorption demonstrated that fractionation of SRFA on the basis of molecular size occured. UV molar absorptivities measured at 280 nm also decreased, which suggests that the more aromatic moieties are preferentially adsorbed. Potentiometric titrations conducted on SRFA revealed changes in the conditional acidity constants (expressed as the negative logarithm, p Ka) of the fulvic acid after adsorption. The increased p Ka value of the humic material remaining in the solution after adsorption implies that the strongly sorbing compounds possessed stronger acidic functional groups. Fractionation of PMA after adsorption, however, did not occur to the same extent compared to SRFA because PMA is relatively homogeneous. The experimental results confirm that molecular weight, aromaticity, and organic acidity are major factors controlling the fractionation of natural organic matter (NOM) by adsorption onto hydrous mineral oxides. PMA, a relatively uniform and less polydisperse organic polymer, may serve as an endmember material characteristic of NOM that exhibits the least amount of fractionation upon adsorption.

  20. Technological and economic potential of poly(lactic acid) and lactic acid derivatives

    SciTech Connect

    Datta, R.; Tsai, S.P.; Bonsignore, P.; Moon, S.H.; Frank, J.R.

    1993-10-01

    Lactic acid has been an intermediate-volume specialty chemical (world production {approximately}40,000 tons/yr) used in a wide range of food processing and industrial applications. lactic acid h,as the potential of becoming a very large volume, commodity-chemical intermediate produced from renewable carbohydrates for use as feedstocks for biodegradable polymers, oxygenated chemicals, plant growth regulators, environmentally friendly ``green`` solvents, and specially chemical intermediates. In the past, efficient and economical technologies for the recovery and purification of lactic acid from crude fermentation broths and the conversion of tactic acid to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. The development and deployment of novel separations technologies, such as electrodialysis (ED) with bipolar membranes, extractive distillations integrated with fermentation, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The use of bipolar ED can virtually eliminate the salt or gypsum waste produced in the current lactic acid processes. In this paper, the recent technical advances in tactic and polylactic acid processes are discussed. The economic potential and manufacturing cost estimates of several products and process options are presented. The technical accomplishments at Argonne National Laboratory (ANL) and the future directions of this program at ANL are discussed.

  1. Electrochemical synthesis of poly(3-aminophenylboronic acid) in ethylene glycol without exogenous protons.

    PubMed

    Wang, Feifan; Zou, Feixue; Yu, Xinxin; Feng, Zhenyu; Du, Na; Zhong, Yaohua; Huang, Xirong

    2016-04-21

    A non-aqueous solution of tetra-n-butylammonium fluoride (TBAF) in ethylene glycol has been tried for the first time as a supporting electrolyte for the electropolymerization of 3-aminophenylboronic acid (APBA). Unlike the traditional acidic aqueous solution, the present medium needs no exogenous protons; moreover, the presence of CF3COOH is found to be unfavorable for the polymerization. The protons are in situ generated by the reaction between the boronic acid group on APBA and 1,2-dihydroxyl on ethylene glycol. So, ethylene glycol serves as not only the solvent but also the proton source. As a part of the supporting electrolyte, F(-) is found to be involved in the electrochemical synthesis of poly(3-aminophenylboronic acid) (PAPBA), but it is not indispensable. Studies on the electropolymerization process indicate that the size of the ions in the electrolyte affects the rate of the doping/dedoping process. The smaller the cation, the easier the doping/dedoping process, and the better the stability of the grown film. As demonstrated by Fourier transform infrared spectra, UV-vis spectra, and scanning electron microscopy, the obtained PAPBA is a cross-linked nanoporous polymer membrane that has a good adherence to the glassy carbon electrode. PMID:27004602

  2. Complexation between poly(maleic acid/octyl vinyl ether) and poly(vinyl caprolactam) in aqueous solution and at the alumina/water interface.

    PubMed

    Qiu, Q; Somasundaran, P

    2002-09-01

    Solution and interfacial properties of binary polymer mixtures of poly(maleic acid/octyl vinyl ether) (PMAOVE) and poly(vinyl caprolactam) (PVCAP) have been studied for the alumina/water system. To test the hydrophobic effect, mixtures of poly(maleic acid/methyl vinyl ether) (PMAMVE) and PVCAP are also investigated and compared to the behavior of PMAOVE/PVCAP. At low pH, both polymer mixtures become turbid upon mixing. The turbidity increases at low mixing ratios of PVCAP to the vinyl ether component, reaches a maximum, and then decreases at higher mixing ratios. Upon shifting the pH to the alkaline range, i.e., pH 7.5 and above, the turbid solution becomes clear for both the polymer mixtures. Cloud point measurements indicate the absence of complexation of PVCAP with PMAMVE under the alkaline conditions, but strong interaction with PMAOVE. This is attributed to the different forces involved in the complexation among the polymers: H bonding for PVCAP/PMAMVE and both H bonding and hydrophobic effects for PVCAP/PMAOVE. At the alumina/water interface, the normally nonadsorbing PVCAP is triggered to adsorb by PMAOVE, attributed to the hydrophobic complexation between the two. However, the adsorption of PVCAP shows a maximum as a function of the concentration of PMAOVE. At concentrations of PMAOVE above the onset of its own plateau adsorption, the amount of PVCAP triggered to adsorb is reduced possibly due to the polymer complex formation in solution. PMID:16290852

  3. Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

    PubMed Central

    Paik, Bradford A.; Blanco, Marco A.; Jia, Xinqiao; Roberts, Christopher J.; Kiick, Kristi L.

    2015-01-01

    Polymer-peptide conjugates were produced via the copper-catalyzed alkyne-azide cycloaddition of poly(tert butyl acrylate) (PtBA) and elastin-like peptides. An azide-functionalized polymer was produced via atom-transfer radical polymerization (ATRP) followed by conversion of bromine end groups to azide groups. Subsequent reaction of the polymer with a bis-alkyne-functionalized, elastin-like peptide proceeded with high efficiency, yielding di- and tri-block conjugates, which after deprotection, yielded poly(acrylic acid) (PAA)-based diblock and triblock copolymers. These conjugates were solubilized in dimethyl formamide, and titration of phosphate buffered saline (PBS) induced aggregation. The presence of polydisperse spherical aggregates was confirmed by dynamic light scattering and transmission electron microscopy. Additionally, a coarse-grained molecular model was designed to reasonably capture inter- and intramolecular interactions for the conjugates and its precursors. This model was used to assess the effect of the different interacting molecular forces on the conformational thermodynamic stability of the copolymers. Our results indicated that the PAA’s ability to hydrogen-bond with both itself and the peptide is the main interaction for stabilizing the diblocks and triblocks and driving their self-assembly, while interactions between peptides are suggested to play only a minor role on the conformational and thermodynamic stability of the conjugates. PMID:25611563

  4. The Pharmacokinetics and Pharmacodynamics of Lidocaine-Loaded Biodegradable Poly(lactic-co-glycolic acid) Microspheres

    PubMed Central

    Liu, Jianming; Lv, Xin

    2014-01-01

    The purpose of this study was to develop novel lidocaine microspheres. Microspheres were prepared by the oil-in-water (o/w) emulsion technique using poly(d,l-lactide-co-glycolide acid) (PLGA) for the controlled delivery of lidocaine. The average diameter of lidocaine PLGA microspheres was 2.34 ± 0.3 μm. The poly disperse index was 0.21 ± 0.03, and the zeta potential was +0.34 ± 0.02 mV. The encapsulation efficiency and drug loading of the prepared microspheres were 90.5% ± 4.3% and 11.2% ± 1.4%. In vitro release indicated that the lidocaine microspheres had a well-sustained release efficacy, and in vivo studies showed that the area under the curve of lidocaine in microspheres was 2.02–2.06-fold that of lidocaine injection (p < 0.05). The pharmacodynamics results showed that lidocaine microspheres showed a significant release effect in rats, that the process to achieve efficacy was calm and lasting and that the analgesic effect had a significant dose-dependency. PMID:25268618

  5. pH effect of coagulation bath on the characteristics of poly(acrylic acid)-grafted and poly(4-vinylpyridine)-grafted poly(vinylidene fluoride) microfiltration membranes.

    PubMed

    Ying, Lei; Zhai, Guangqun; Winata, A Y; Kang, E T; Neoh, K G

    2003-09-15

    The poly(acrylic acid)-graft-poly(vinylidene fluoride) (PAAc-g-PVDF) and poly(4-vinylpyridine)-graft-poly(vinylidene fluoride) (P4VP-g-PVDF) copolymers were obtained by thermally induced molecular graft copolymerization of acrylic acid (AAc) and 4-vinylpyridine (4VP), respectively, with the ozone-pretreated poly(vinylidene fluoride) (PVDF) in N-methyl-2-pyrrolidone (NMP) solution. Microfiltration (MF) membranes were prepared from the respective copolymers by phase inversion in aqueous media. The effects of pH of the coagulation bath on the physicochemical and morphological characteristics of the membranes were investigated. The surface compositions of the membranes were determined by X-ray photoelectron spectroscopy (XPS). The surface graft concentration of the AAc polymer for the PAAc-g-PVDF MF membrane increased with decreasing pH value of the coagulation bath. Completely opposite pH-dependent behavior was observed for the surface graft concentration of the 4VP polymer in the P4VP-g-PVDF MF membranes. A substantial increase in mean pore size was observed for the PAAc-g-PVDF MF membranes cast in basic coagulation baths of increasing pH. In the case of the P4VP-g-PVDF MF membranes, a substantial increase in mean pore size was observed for membranes cast in low pH (acidic) baths. The permeation rate of aqueous solutions through the PAAc-g-PVDF and P4VP-g-PVDF MF membranes exhibited a reversible dependence on the pH of the solution, with the membranes cast near the neutral pH exhibiting the highest sensitivity to changes in permeate pH. PMID:12962674

  6. Synthesis and characterization of pH-sensitive poly(itaconic acid)-poly(ethylene glycol)-folate-poly(l-histidine) micelles for enhancing tumor therapy and tunable drug release.

    PubMed

    Sun, Yuan; Li, Yapeng; Nan, Shuli; Zhang, Liangzi; Huang, Hailong; Wang, Jingyuan

    2015-11-15

    pH responsive intracellular tumor targeting is increasingly investigated as a pathway to trigger the release of anti-tumor drugs once the drug carrier reached the unique acidic environment of the solid tumors or after the drug carrier has been taken up by cells, resulting in the localization of the micelles in the acidic endosomes and lysosomes. Poly(itaconic acid)-poly(ethylene glycol)-folate-poly(l-histidine) (PIA-PEG-FA-PHIS) was synthesized as a carrier for tumor-targeted drug delivery. The micelles were internalized by receptor-mediated endocytosis, and the combination of active targeting and triggered release resulted in apparent cytotoxicity and antitumor activity. The MTT assay showed DOX-loaded micelles had higher and obvious cytotoxicity against Hela cells at pH 5.0 than that at pH 7.4. Cellular uptake experiments revealed that these pH-responsive PIA-PEG-FA-PHIS micelles were taken up in great amounts by receptor-mediated endocytosis and delivered to lysosomes, triggering release of DOX into the cytoplasm. These indicated that the PIA-PEG-FA-PHIS micelles could be a promising drug delivery system with preeminent stability for targeting the hydrophobic drugs to cancer cells and releasing DOX in to the cells by sensing the acidic environment of the endosomes for cancer therapy. PMID:26210102

  7. Determination of uric acid level by polyaniline and poly (allylamine): Based biosensor.

    PubMed

    Wathoni, Nasrul; Hasanah, Aliya Nur; Gozali, Dolih; Wahyuni, Yeni; Fauziah, Lia Layusa

    2014-01-01

    The uric acid biosensor has been much developed by immobilizing uricase enzyme into the membrane of conductive polymer and the membrane of polyelectrolyte such as polyaniline (PANI) and poly (allylamine) (PAA) respectively. The purpose of this research was to create a new amperometric uric acid biosensor by immobilization of uricase in combination between PANI and PAA membranes. The working electrode was Pt plate (0.5 mm). The auxiliary and the reference electrode were Pt wire 0.4 mm and Ag/AgCl respectively. Uricase, uric acid, PAA, pyrrole and glutaraldehyde were supplied from Sigma. All other chemical was obtained from Merck. The biosensor was created by immobilizing of uricase by a glutaraldehyde crosslinking procedure on PANI composite film on the surface of a platinum electrode while the polyelectrolyte layer of PAA were prepared via layer-by-layer assembly on the electrode, functioning as H2O2-selective film. Standard of deviation, coefficient of variation (CV) and coefficient of correlation (r) analysis were used in this study. The biosensor had a good linearity with a correlation coefficient of 0.993 and it could be used up to 27 times with the CV value of 3.97%. The presence of other compounds such as glucose and ascorbic acid gave 1.3 ± 1.13% and 3.27 ± 2.29% respectively on the interference effect toward the current response of uric acid biosensor. The polymer combination of PANI and PAA can be used as a selective matrix of uric acid biosensor. PMID:24696812

  8. Dynamics of the layer-by-layer assembly of a poly(acrylic acid)-lanthanide complex colloid and poly(diallyldimethyl ammonium).

    PubMed

    Xu, Jiali; Wang, Zhiliang; Wen, Lingang; Zhou, Xianju; Xu, Jian; Yang, Shuguang

    2016-01-21

    Poly(acrylic acid) (PAA) and lanthanide (Ln) ions, such as Ce(3+), Eu(3+), and Tb(3+), were prepared as dispersed complex colloidal particles through three different protocols with rigorous control of the pH value and mixing ratio. The negatively charged PAA-Ln complex particles were layer-by-layer (LbL) assembled with positively charged poly(diallyldimethyl ammonium) (PDDA) to prepare a thin film. The film thickness growth is much quicker than PDDA/PAA film. Due to the incorporation of Ln(3+) ions, the film exhibits fluorescence. During LbL assembly, PDDA-PAA association based on electrostatic force and PAA-Ce association based on coordination are in competition, which leads to the LbL assembly of PDDA and PAA-Ln complex colloidal particles being a complicated dynamic process. PMID:26549538

  9. A novel phosphoric acid doped poly(ethersulphone)-poly(vinyl pyrrolidone) blend membrane for high-temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Wang, Haining; Lu, Shanfu; Guo, Zhibin; Rao, Siyuan; Xiu, Ruijie; Xiang, Yan

    2015-07-01

    A high-temperature proton exchange membrane, poly(ethersulphone)-poly(vinyl pyrrolidone) (PES-PVP) blend membrane is successfully prepared by scalable polymer blending method. The physical properties of blend membrane are characterized by DSC, TG and tensile strength test. The DSC and TG results indicate PES-PVP blend membranes possess excellent thermal stability. After phosphoric acid (PA) doping treatment, the blend membrane shows enhanced proton conductivity. PA doping level and volume swelling ratio of the blend membrane are found to be positively related to the PVP content. A high proton conductivity of 0.21 S/cm is achieved at 180 °C for PA doped PES-PVP 80% with a PA doping level of 9.1. PEM fuel cell based on PA doped PES-PVP 80% membrane shows a high power density of 850 mW/cm2 and outstanding stability at 180 °C without extra humidification.

  10. Poly(brilliant green) and poly(thionine) modified carbon nanotube coated carbon film electrodes for glucose and uric acid biosensors.

    PubMed

    Ghica, M Emilia; Brett, Christopher M A

    2014-12-01

    Poly(brilliant green) (PBG) and poly(thionine) (PTH) films have been formed on carbon film electrodes (CFEs) modified with carbon nanotubes (CNT) by electropolymerisation using potential cycling. Voltammetric and electrochemical impedance characterisation were performed. Glucose oxidase and uricase, as model enzymes, were immobilised on top of PBG/CNT/CFE and PTH/CNT/CFE for glucose and uric acid (UA) biosensing. Amperometric determination of glucose and UA was carried out in phosphate buffer pH 7.0 at -0.20 and +0.30 V vs. SCE, respectively, and the results were compared with other similarly modified electrodes existing in the literature. An interference study and recovery measurements in natural samples were successfully performed, indicating these architectures to be good and promising biosensor platforms. PMID:25159399

  11. A study of structure and dynamics of poly(aspartic acid) sodium/poly(vinyl alcohol) blends by 13C CP/MAS NMR

    NASA Astrophysics Data System (ADS)

    Wang, P.; Ando, I.

    1999-09-01

    Solid state 13C CP/MAS NMR measurements have been carried out on poly(aspartic acid) sodium (PAANa)/poly(vinyl alcohol) (PVA) blends over a wide range of temperatures. From these experimental results, it is found that the main-chain conformations of PAANa in PAANa/PVA blends take the α-helix form over a wide range of blend ratios, and, in contrast, the conformation and dynamics of the side chains of PAANa are strongly influenced by the formation of an intermolecular hydrogen bond between the carboxyl group of the side chains and the hydroxyl group of PVA. The behavior of the proton spin-lattice relaxation times in the rotating frame ( T1 ρ(H)) and the laboratory frame ( T1(H)) indicates that when the blend ratio of PAANa and PVA is 1:1, they are miscible.

  12. pH-sensing properties of cascaded long- and short-period fiber grating with poly acrylic acid/poly allylamine hydrochloride thin-film overlays

    NASA Astrophysics Data System (ADS)

    Yang, Ying

    2014-11-01

    Based on coupled-mode theory and transfer matrix method, the mode coupling mechanism and the reflection spectral properties of coated cascaded long- and short-period gratings (CLBG) are discussed. The effects of the thin-film parameters (film refractive index and film thickness) on the reflection spectra of the coated CLBG are simulated. By using electrostatic self-assembly method, poly acrylic acid (PAA) and poly allylamine hydrochloride (PAH) multilayer molecular pH-sensitive thin-films are assembled on the surface of the partial corroded CLBG. When the CLBG coated with PAA/PAH films are used to sense pH values, the resonant wavelengths of the CLBG have almost no shift, whereas the resonance peak reflectivities change with pH values. In addition, the sensitivities of the resonance peak reflectivities responding to pH values are improved by an order of magnitude.

  13. Poly-N-acetylglucosamine and poly(glycerol phosphate) teichoic acid identification from staphylococcal biofilm extracts using excitation sculptured TOCSY NMR.

    PubMed

    Wagstaff, Jane L; Sadovskaya, Irina; Vinogradov, Evgeny; Jabbouri, Saïd; Howard, Mark J

    2008-02-01

    We report the successful application of selective excitation sculptured TOCSY NMR (SXS-TOCSY) to identify individual solution components from a heterogeneous system using selectively acquired (1)H NMR spin system patterns. SXS-TOCSY application is illustrated by detection of the simultaneous presence of poly-beta-(1,6)-N-acetylglucosamine (PNAG) and poly(glycerol phosphate) teichoic acid (TA) carbohydrate polymer components in crude biofilm extracts from Staphylococcus epidermidis without the need for further sample purification and component separation. Biofilms are implicated in the barriers for resistance of microbes toward antibiotics and immune responses, therefore efficient rapid detection and quantification of key components are important to assist in the design of a clinical infection response. PMID:18213410

  14. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension using hydrophobically modified poly(acrylic acid).

    PubMed

    Chen, J; Chen, M C

    2011-01-01

    A series of hydrophobically modified poly(acrylic acid) (PAA), poly(2-phenoxyethyl acrylate-co-acrylic acid) (poly(PHEA-co-AA)), have been synthesized and characterized by Ubbelohde type viscometry, Nuclear Magnetic Resonance (1H NMR) spectrometry and Differential Scanning Calorimetry (DSC). The shear thinning Non-Newtonian fluid behavior of their aqueous solution and the dependence on pH and hydrophobic group contents were found through apparent viscosity and rheological property investigating. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension was evaluated through visible absorbance data. Decolourization performance of hydrophobically associated polymer indicates two times better than that of PAA. The quantitative relationship was mainly studied. PMID:21866762

  15. Hydrolytic degradation behaviour of sucrose palmitate reinforced poly(lactic acid) nanocomposites.

    PubMed

    Valapa, Ravi Babu; G, Pugazhenthi; Katiyar, Vimal

    2016-08-01

    This work discusses the influence of novel biofiller, "sucrose palmitate" (SP) on the hydrolytic degradation behavior of poly(lactic acid) (PLA) nanocomposites. The influence of temperature and pH of the solution on the hydrolytic degradation behavior of PLA and PLA-SP nanocomposites was investigated. The variation in the crystallinity of PLA and PLA composites subjected to the hydrolytic degradation process is verified by XRD and DSC analysis. The morphological changes that occurred during the degradation process are observed by scanning electron microscopy (SEM). Thermo-gravimetric analysis confirms the loss of thermal stability of the neat PLA as well as composites after hydrolytic degradation process. Transparency measurements support the enhancement in opacity of both the PLA and PLA-SP nanocomposites with progress in hydrolytic degradation period. PMID:27095433

  16. Electrical behavior of polymer hydrogel composed of poly(vinyl alcohol)/hyaluronic acid in solution

    NASA Astrophysics Data System (ADS)

    Kim, Seon Jeong; Yoon, Seoung Gil; Park, Sang Jun; Lee, Chang Kee; Shin, Su Ryon; Lee, Young Moo; Kim, In Young; Kim, Sun I.

    2003-07-01

    Interpenetrating polymer networks (IPN) composed of poly(vinyl alcohol) (PVA) and hyaluronic acid (HA) were prepared and exhibited electrical sensitive behavior. The swelling behavior of the PVA/HA IPN was studied by immersion of the gel in aqueous NaCl solutions at various concentrations and pHs. Also, the stimuli response of the PVA/HA IPN in electric fields was investigated. When swollen IPN was placed between a pair of electrodes, the PVA/HA IPN exhibited bending behavior upon the application of an electric field. The PVA/HA IPN also showed stepwise bending behavior depending on the electric stimulus. Also, for using biomedical application, the bending behavior of PVA/HA IPN has been studied in hank"s solution at pH 7.4

  17. Cellulose-nanofiber-reinforced poly(lactic acid) composites prepared by a water-based approach.

    PubMed

    Wang, Tao; Drzal, Lawrence T

    2012-10-24

    The difficulty of dispersing cellulose nanofibers (CNFs) in hydrophobic polymers such as poly(lactic acid) (PLA) remains a major obstacle to the expansion of cellulose nanocomposite applications. In this work, we employed the solvent evaporation technique commonly used for drug microencapsulation to suspend PLA in water as microparticles. The suspension of the microparticles was easily mixed with the CNFs prepared by high-pressure homogenization. Water removal by membrane filtration produced CNF sheets filled with the particles. Compression molding of the stacked sheets resulted in nanocomposites with good CNF dispersions. Increases in the modulus and strength (up to 58% and 210%, respectively) demonstrated the load-bearing capability of the CNF network in the composites. PMID:22991937

  18. Fabrication of multifunctional cellulose nanocrystals/poly(lactic acid) nanocomposites with silver nanoparticles by spraying method.

    PubMed

    Yu, Hou-Yong; Yang, Xing-Yuan; Lu, Fang-Fang; Chen, Guo-Yin; Yao, Ju-Ming

    2016-04-20

    The poly (lactic acid) (PLA)/functionalized cellulose nanocrystals formates (CNFs) were prepared by solution casting and then the binary films were sprayed with silver ammonia aqueous solution to fabricate PLA/CNF/Ag ternary nanocomposites. It was found that both deposited silver (Ag) nanoparticles and CNFs showed efficient reinforcing effect on the thermal, mechanical, barrier properties and antibacterial activity of PLA matrix. Especially, the maximum decomposition temperature (Tmax) and Young's modulus of PLA/CNF/Ag(6) nanocomposite film increased by 15.5°C and 48.7%, respectively. Meanwhile an obvious reduction in the water vapor permeability was detected. Furthermore, the migration levels of the ternary nanocomposite films were well below the permitted limits in both non-polar and polar food simulants (60mgkg(-1)), and they showed a significant antibacterial activity influenced by the Ag contents. This study reveals that the novel nanocomposite films will offer a good perspective for food packaging applications. PMID:26876846

  19. Cascade enzymatic catalysis in poly(acrylic acid) brushes-nanospherical silica for glucose detection.

    PubMed

    Zhao, Yan; Wang, Ying; Zhang, Xiaobin; Kong, Rongmei; Xia, Lian; Qu, Fengli

    2016-08-01

    The ultrasensitive monitoring of glucose with a fast and accurate method is significant in potential therapeutics and optimizes protein biosynthesis. Incorporation of enzyme into matrix is considered as promising candidates for constructing highly sensitive glucose-responsive systems. In this study, three-dimensional poly(acrylic acid) brushes-nanospherical silica (PAA-nano silica) with high amplification capability and stability were used to covalently immobilize bienzymes for cascade enzymatic catalysis. The major advantages of PAA-nano silica-bienzyme co-incorporation is that the enzymes are proximity distribution, and such close confinement both minimized the diffusion of intermediates among the enzymes in the consecutive reaction and improve the utilization efficiency of enzymes, thereby enhancing the overall reaction efficiency and specificity. Thus, this present bienzymatic biosensor shows robust signal amplification and ultrasensitivity of glucose-responsive properties with a detection limit of 0.04μM. PMID:27216683

  20. Biodegradation of poly(lactic acid) and some of its based systems with Trichoderma viride.

    PubMed

    Lipsa, Rodica; Tudorachi, Nita; Darie-Nita, Raluca Nicoleta; Oprică, Lacramioara; Vasile, Cornelia; Chiriac, Aurica

    2016-07-01

    The purpose of this study was to assess the biodegradation of poly(lactic acid) (PLA) and some plasticized PLA based systems by Trichoderma viride fungus, in liquid medium and controlled laboratory conditions. The studied systems were achieved using PLA, hydrolyzed collagen (HC) as biological macromolecules and other additives by melt processing procedure. PLA and the systems' biodegradability was examined by the weight losses of the samples (after 7 and 21 days of exposure) and FTIR-ATR, GPC, SEM analyses (after 21 fungus inoculation days). The thermogravimetry (TG-DTG) study showed that the thermostability of the samples decreased after biodegradation and was influenced by the chemical structure of the systems' components. PMID:27064086

  1. Effect of iron poly (sorbitolgluconic acid) complex on urinary cellular excretion.

    PubMed

    Elliott, H L; Lawrence, J R; Campbell, B C; Goldberg, A; Smart, L E

    1981-01-01

    The intramuscular injection of 250 mg iron poly (sorbitol-gluconic acid) complex caused no increase in urinary cellular or bacterial excretion in 8 patients with chronic pyelonephritis, 4 patients with non-infective renal disease, and 4 controls. However, in 4 patients with chronic infective disease of the renal tract given 500 g there was a significant increase in cellular excretion. This response was not seen in 2 control patients, nor in 2 patients with non-infective renal disease. Using a differential staining technique, this increase in urinary cellular excretion was found to be due, not to leucocytes, but to renal tubular cells. The precise significance of this is unclear, but there would be concern that the high concentration of excreted iron was providing a 'toxic' insult to susceptible, infection-damaged cells. PMID:7226874

  2. A pharmacokinetic and clinical evaluation of iron poly (sorbitol-gluconic acid) complex.

    PubMed

    Campbell, B C; Lawrence, J R; Sumner, D J; Kelman, A; Smith, A; Elliott, H L; Goldberg, A

    1980-01-01

    The pharmacokinetics of iron poly (sorbitol-gluconic acid) complex (IPSG) were studied following a single intramuscular injection of 59Fe-labelled IPSG to 4 iron deficient-patients. The results showed a more rapid uptake of iron from the site of injection than that reported with iron dextran while there was a lower urinary excretion than found with iron sorbitol citrate. A clinical study was carried out in 11 patients with iron deficiency anaemia. Patients were allocated at random to receive IPSG as either 250 mg or 500 mg elemental iron per week for 8 weeks. A satisfactory response to therapy was obtained with each regimen whether measured by an increase in haemoglobin concentration or in serum ferritin concentration. Few side-effects were encountered but discomfort and staining at the injection site was found on the higher dose schedule. PMID:7208542

  3. Direct determination of creatinine based on poly(ethyleneimine)/phosphotungstic acid multilayer modified electrode.

    PubMed

    Han, Ping; Xu, Shimei; Feng, Shun; Hao, Yanjun; Wang, Jide

    2016-05-01

    In this work, the direct determination of creatinine was achieved using a poly(ethyleneimine)/phosphotungstic acid multilayer modified electrode with the assistance of Copper(II) ions by cyclic voltammetry. The quantity of creatinine were determined by measuring the redox peak current of Cu(II)-creatinine complex/Cu(I)-creatinine complex. Factors affecting the response current of creatinine at the modified electrode were optimized. A linear relationship between the response current and the concentration of creatinine ranging from 0.125 to 62.5μM was obtained with a detection limit of 0.06μM. The proposed method was applied to determine creatinine in human urine, and satisfied results were gotten which was validated in accordance with high performance liquid chromatography. The proposed electrode provided a promising alternative in routine sensing for creatinine without enzymatic assistance. PMID:26946017

  4. New Poly(amino acid methacrylate) Brush Supports the Formation of Well-Defined Lipid Membranes

    PubMed Central

    2015-01-01

    A novel poly(amino acid methacrylate) brush comprising zwitterionic cysteine groups (PCysMA) was utilized as a support for lipid bilayers. The polymer brush provides a 12-nm-thick cushion between the underlying hard support and the aqueous phase. At neutral pH, the zeta potential of the PCysMA brush was ∼−10 mV. Cationic vesicles containing >25% DOTAP were found to form a homogeneous lipid bilayer, as determined by a combination of surface analytical techniques. The lipid mobility as measured by FRAP (fluorescence recovery after photobleaching) gave diffusion coefficients of ∼1.5 μm2 s–1, which are comparable to those observed for lipid bilayers on glass substrates. PMID:25746444

  5. Synthesis of potent inhibitors of anthrax toxin based on poly-L-glutamic acid.

    PubMed

    Joshi, Amit; Saraph, Arundhati; Poon, Vincent; Mogridge, Jeremy; Kane, Ravi S

    2006-01-01

    We report the synthesis of biodegradable polyvalent inhibitors of anthrax toxin based on poly-L-glutamic acid (PLGA). These biocompatible polyvalent inhibitors are at least 4 orders of magnitude more potent than the corresponding monovalent peptides in vitro and are comparable in potency to polyacrylamide-based inhibitors of anthrax toxin assembly. We have elucidated the influence of peptide density on inhibitory potency and demonstrated that these inhibitory potencies are limited by kinetics, with even higher activities seen when the inhibitors are preincubated with the heptameric receptor-binding subunit of anthrax toxin prior to exposure to cells. These polyvalent inhibitors are also effective at neutralizing anthrax toxin in vivo and represent attractive leads for designing biocompatible anthrax therapeutics. PMID:16984137

  6. Synthesis and accumulation of poly(3-hydroxybutyric acid) by Rhizobium sp.

    PubMed

    Manna, A; Pal, S; Paul, A K

    2000-01-01

    Forty-two Rhizobium strains obtained from different culture collections were evaluated quantitatively for poly(3-hydroxy-butyric acid) [PHB] production in shake flask culture. The majority of the strains produced the maximum amount of PHB during the late exponential or stationary phase of growth. Synthesis and accumulation of PHB in different species of Rhizobium were found to vary between 1-38% of their dry biomass. Growth and PHB production by the Rhizobium strain TAL-640 were greatly influenced by the C-source and D-mannitol was fundamental to both processes. The identity and purity of PHB isolated from TAL-640 have also been confirmed by UV-, IR- and 1H-NMR spectroscopic analyses. PMID:10866363

  7. Electrospinning of curcumin loaded chitosan/poly (lactic acid) nanofilm and evaluation of its medicinal characteristics

    NASA Astrophysics Data System (ADS)

    Dhurai, Bhaarathi; Saraswathy, Nachimuthu; Maheswaran, Ramasamy; Sethupathi, Ponnusamy; Vanitha, Palanisamy; Vigneshwaran, Sukumar; Rameshbabu, Venugopal

    2013-12-01

    The curcumin loaded chitosan/poly (lactic acid) (PLA) nanofibers were produced using electrospinning. Box—Behnken experimental design was used for the optimization of variables (-1, 0, + 1 coded level) like chitosan/PLA strength (% w/v), curcumin strength (% w/v) and applied voltage (kV) to obtain uniform fiber diameter. The morphology of nanofibers was shown by SEM. Molecular interactions and the presence of each chemical compound of curcumin loaded chitosan/PLA fibers were characterized by FTIR and EDX analysis. Antioxidant, drug release and in vitro cytotoxicity tests were performed to evaluate the suitability of nanofibers that would be used for wound healing. In vivo wound healing studies on excision and incision wounds created on rat model showed significant reduction of wound area when compared to untreated. The better healing efficiency can be attributed to the presence of curcumin and chitosan.

  8. Impact property enhancement of poly (lactic acid) with different flexible copolymers

    NASA Astrophysics Data System (ADS)

    Likittanaprasong, N.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    The objective of this work was to improve the impact property of Poly (lactic acid) (PLA) by blending with different copolymers. Six flexible copolymers, namely, acrylonitrile butadiene styrene (ABS) powder, Biomax, polybutyrate adipate co-terephthalate (PBAT), polyether block amide (PEBAX), ethylene-vinyl acetate (EVA) and ethylene acrylic elastomer (EAE), with loading less than 20wt% were used and compared. The rheological, mechanical and morphological properties of samples were investigated by melt flow index, tensile testing, impact testing and scanning electron microscope (SEM), respectively. It was found that PLA added 20wt% EAE showed the highest impact strength (59.5 kJ/m2), which was 22 times higher than neat PLA. The elongation at break was also increased by 12 folds compared to neat PLA. The SEM images showed good interface and distribution for PLA containing 20wt% EAE, 15 phr Biomax and 20 wt% PEBAX.

  9. Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Shibata, Akimichi; Yada, Shuhei; Terakawa, Mitsuhiro

    2016-06-01

    Biodegradation is a key property for biodegradable polymer-based tissue scaffolds because it can provide suitable space for cell growth as well as tailored sustainability depending on their role. Ultrashort pulsed lasers have been widely used for the precise processing of optically transparent materials, including biodegradable polymers. Here, we demonstrated the change in the biodegradation of a poly(lactic-co-glycolic acid) (PLGA) following irradiation with femtosecond laser pulses at different wavelengths. Microscopic observation as well as water absorption and mass change measurement revealed that the biodegradation of the PLGA varied significantly depending on the laser wavelength. There was a significant acceleration of the degradation rate upon 400 nm-laser irradiation, whereas 800 nm-laser irradiation did not induce a comparable degree of change. The X-ray photoelectron spectroscopy analysis indicated that laser pulses at the shorter wavelength dissociated the chemical bonds effectively, resulting in a higher degradation rate at an early stage of degradation.

  10. Amylopectin grafted with poly (acrylic acid): development and application of a high performance flocculant.

    PubMed

    Sarkar, Amit Kumar; Mandre, N R; Panda, A B; Pal, Sagar

    2013-06-20

    In recent years, wastewater treatment, especially for wastewaters which are not suitably recycled by conventional or normal biological processes, is getting more importance. Of late, natural biopolymer based flocculants are extensively used for wastewater treatment because of low cost, environment-friendly and easily availablility from reproducible farm and forest resources. This article introduces the development of a natural polymer based flocculant [amylopectin grafted with poly (acrylic acid) - AP-g-PAA] for treatment of synthetic effluent as well as mining industry wastewater. The graft copolymer based flocculants have been developed under optimum conditions and characterized using viscometry, (13)C NMR, SEM, TGA, rheological characteristics, determination of hydrodynamic radius and CHN analysis. The flocculation characteristics of grafted and ungrafted polysaccharide have been evaluated in synthetic effluents (as Fe-ore, kaolin, Mn ore suspensions) as well as in mining industry wastewater. PMID:23648038

  11. Influence of different sterilization processes on the properties of commercial poly(lactic acid).

    PubMed

    Savaris, M; Santos, V Dos; Brandalise, R N

    2016-12-01

    This study aims at analyzing the modifications in the morphological, physical, chemical and thermal properties of commercial poly(lactic acid) (PLA) films after exposure to five different sterilization processes. Films were obtained by compression molding, hygienized and sterilized by ethylene oxide (SEtO), hydrogen peroxide plasma (SH2O2), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLASEtO, PLASH2O2, PLASEB and PLASGR exhibited thermal and physical changes after being submitted to sterilization processes. PLASSS showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH2O2, SEB and EGR can be applied for the sterilization of PLA films and the SSS process is not recommended in view of the data obtained and test conditions reported in this study for PLA films. PMID:27612759

  12. Electrophoretic Mobility of Poly(acrylic acid)-Coated Alumina Particles

    SciTech Connect

    Bhosale, Prasad S.; Chun, Jaehun; Berg, John C.

    2011-06-01

    The effect of poly (acrylic acid) (PAA) adsorption on the electrokinetic behavior of alumina dispersions under high pH conditions was investigated as a function of polymer concentration and molecular weight as well as the presence, concentration and ion type of background electrolyte. Systems of this type are relevant to nuclear waste treatment, in which PAA is known to be an effective rheology modifier. The presence of all but the lowest molecular weight PAA studied (1800) led to decreases in dynamic electrophoretic mobility at low polymer concentrations, attributable to bridging flocculation, as verified by measurements of particle size distribution. Bridging effects increased with polymer molecular weight, and decreased with polymer concentration. Increases in background electrolyte concentration enhanced dynamic electrophoretic mobility as the polymer layers were compressed and bridging was reduced. Such enhancements were reduced as the cation was changed from Na+ to K+ to Cs+.

  13. Sorption of Pb(ll) by poly(hydroxamic acid) grafted oil palm empty fruit bunch.

    PubMed

    Haron, M J; Tiansin, M; Ibrahim, N A; Kassim, A; Wan Yunus, W M Z; Talebi, S M

    2011-01-01

    This paper describes the sorption of Pb(ll) from aqueous solution. Oil palm empty fruit bunch (OPEFB) fiber was first grafted with poly(methylacrylate) and then treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid (PHA) grafted OPEFB. Sorption of Pb(ll) by PHA-OPEFB was maximum at pH 5. The sorption followed the Langmuir model with maximum capacityof 125.0 mg g-1 at 25 degrees C. The sorption process was exothermic, as shown by the negative value of enthalpy change, Delta H0. The free energy change (DeltaG0) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Pb(ll) sorption followed a second order kinetic model. PMID:21866782

  14. The properties of antimicrobial films derived from poly(lactic acid)/starch/chitosan blended matrix.

    PubMed

    Bie, Pingping; Liu, Peng; Yu, Long; Li, Xiaoxi; Chen, Ling; Xie, Fengwei

    2013-10-15

    An antimicrobial material with a slow release property was developed based on poly(lactic acid)/starch/chitosan blends, in which chitosan acted as an antimicrobial agent while PLA and starch together were used as a slow-releasing device. An increase in the starch content drastically improved the hydrophilicity of the blends, which was favorable for the diffusion of the embedded chitosan. Moreover, the release of chitosan was observed to occur in two stages, with a very fast release stage initially and a slow but durable release stage as the latter. These two stages exhibited the effectiveness and long residual action of antimicrobial property of the blends respectively, demonstrating the suitability to be used for foods with high water activity, such as fresh meat. The tensile and thermal properties further verified the promising use of the blend material in packaging. PMID:23987434

  15. Structure of poly(lactic-acid) PLA nanofibers scaffolds prepared by electrospinning

    NASA Astrophysics Data System (ADS)

    Gómez-Pachón, E. Y.; Vera-Graziano, R.; Montiel Campos, R.

    2014-06-01

    The structural properties of poly(lactic-acid) PLA nanofiber scaffolds prepared by electrospinning have been correlated with their process condition. The influence of the electrospinning processing parameters on structure including fiber orientation, take-up velocity and post-thermal treatment was analyzed. The structure and the properties of the scaffolds were studied by x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and differential scanning calorimetry (DSC). The existence of crystallinity into the nanofibres of PLA was found. The careful observation by HRTEM shows an amorphous core and a semicrystalline shell structure (supramolecular), and the surface of nanofiber observed by AFM shows a laminate periodic along the main axis of the fiber. These observations will be useful in understanding the structure-property relationships of oriented nanofibre scaffolds for medical or biological applications.

  16. Structure and properties of poly (lactic acid)/Sterculia urens uniaxial fabric biocomposites.

    PubMed

    Jayaramudu, J; Reddy, G Siva Mohan; Varaprasad, K; Sadiku, E R; Ray, S Sinha; Rajulu, A Varada

    2013-05-15

    Uniaxial cellulose fabric Sterculia urens reinforced poly (lactic acid) (PLA) matrix biocomposites were prepared by a two-roll mill. In order to assess the suitability of Sterculia fabric as reinforcement for PLA matrix, the PLA/Sterculia fabric biocomposites were prepared. Tensile parameters, such as maximum stress, Young's modulus and elongation-at-break, were determined using the Universal Testing Machine. The effect of alkali treatment and silane-coupling agent on the tensile properties of PLA-based biocomposites was studied. The results of thermogravimetric analysis show that uniaxial treatment of the fabric can improve the degradation temperature of the biocomposites. Moreover, morphological studies by scanning electron microscopy confirmed that better adhesion between the uniaxial fabric and the matrix was achieved. It was established that standard PLA resins are suitable for the manufacture of S. urens uniaxial fabric reinforced biocomposites with excellent engineering properties, useful for food packaging. PMID:23544638

  17. A review of poly(lactic acid)-based materials for antimicrobial packaging.

    PubMed

    Tawakkal, Intan S M A; Cran, Marlene J; Miltz, Joseph; Bigger, Stephen W

    2014-08-01

    Poly(lactic acid) (PLA) can be synthesized from renewable bio-derived monomers and, as such, it is an alternative to conventional petroleum-based polymers. Since PLA is a relatively new polymer, much effort has been directed toward its development in order to make it an acceptable and effective option to the more traditional petroleum-based polymers. Commercially, PLA has received considerable attention in food packaging applications with a focus on films and coatings that are suitable for short shelf life and ready-to-eat food products. The potential for PLA to be used in active packaging has also been recognized by a number of researchers. This review focuses on the use of PLA in antimicrobial systems for food packaging applications and explores the engineering characteristics and antimicrobial activity of PLA films incorporated and/or coated with antimicrobial agents. PMID:25039867

  18. Water dispersible polytetrafluoroethylene microparticles prepared by grafting of poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Yang, Changqiao; Xu, Lu; Zeng, Hongyan; Tang, Zhongfeng; Zhong, Lei; Wu, Guozhong

    2014-10-01

    Due to the hydrophobic nature and high gravimetric density, it is very difficult to obtain water dispersible polytetrafluoroethylene (PTFE) powder. In this work, hydrophilic PTFE microparticles were successfully prepared by grafting of poly(acrylic acid) onto PTFE micropowder via a pre-irradiation method. The as-obtained hydrophilic PTFE microparticles were analyzed by FT-IR, 1H NMR, CA, SEM and TGA. After neutralization by sodium hydroxide, the water contact angle decreased from 145.69° for pristine PTFE to 63.38° for PTFE-g-NaAA. The obtained micropowder can be easily dispersed in water to form a dispersion with very high stability. Furthermore, the presence of grafted PAA shows no obvious influence on degradation temperature of PTFE backbones.

  19. Holographic gratings recorded in poly(lactic acid)/azo-dye films

    NASA Astrophysics Data System (ADS)

    Cambiasso, Javier; Goyanes, Silvia; Ledesma, Silvia

    2015-09-01

    Diffraction gratings were recorded in biodegradable polymer films of poly(lactic acid) doped with the photoisomerisable azo-dye (Disperse Orange 3). It is shown that the diffraction efficiency of the recorded grating can be improved by 220% via an all-optical treatment. This all-optical treatment consists of a pre-irradiation of the sample with the writing laser beam at high power during a short period of time, preventing damage of the material, followed by a much longer inscription at relatively low power. Furthermore, it is shown that the addition of a small amount of 0.05 wt% of multi-walled carbon nanotubes to the photoresponsive polymer increases the maximum diffraction efficiency as well as the remanent efficiency by 20%. Finally, this last photoresponsive nano-composite is also sensitive to the pre-irradiation treatment.

  20. Scaffolds of Hyaluronic Acid-Poly(Ethyl Acrylate) Interpenetrating Networks: Characterization and In Vitro Studies.

    PubMed

    Rodríguez-Pérez, E; Lloret Compañ, A; Monleón Pradas, M; Martínez-Ramos, C

    2016-08-01

    Hyaluronic acid (HA) provides many advantages to regenerative implants through its bioactive properties, but it also has many limitations as a biomaterial if it is not chemically modified. In order to overcome some of these limitations, HA has been combined with poly(ethyl acrylate) in the form of interpenetrating polymeric networks (IPNs), in which the HA network is crosslinked with divinyl sulfone. Scaffolds of this IPN have been produced through a template-leaching methodology, and their properties have been compared with those of single-network scaffolds made of either PEA or crosslinked HA. A fibroblast cell line has been used to assess the in vitro performance of the scaffolds, revealing good cell response and a differentiated behavior on the IPN surface when compared to the individual polymers. Altogether, the results confirm that this type of material offers an interesting microenvironment for cells, which can be further improved toward its potential use in medical implants. PMID:27072058

  1. Poly(lactic acid) microencapsulated oxytetracycline: in vitro and in vivo evaluation.

    PubMed

    Vidmar, V; Smolcić-Bubalo, A; Jalsenjak, I

    1984-01-01

    Poly(lactic acid) microcapsules of oxytetracycline hydrochloride were prepared by precipitation of the polymer from a solution when a non-solvent was added to a polymer solution in which the drug had been dispersed. Three types of microcapsules were prepared by varying the amount of drug encapsulated, as well as by using two samples of polymer with different molecular weights. The product obtained was of a matrix character consisting of agglomerated capsules. The drug release in vitro, for the best batch, was completed within 12 hours. Serum levels of the drug in rabbits treated by intramuscular injection were prolonged maximally up to 24 hours depending upon the type of microcapsules. PMID:6336522

  2. Clay-filled bio-based blends of poly(lactic acid) and polyamide 11

    NASA Astrophysics Data System (ADS)

    Nuzzo, Anna; Acierno, Domenico; Filippone, Giovanni

    2012-07-01

    We investigate the effect of small amounts of organoclay on the crystallinity and dynamic-mechanical properties of bio-based blends of poly(lactic acid) (PLA) and polyamide 11 (PA11). Virgin and filled blends were prepared by melt-compounding the constituents using a twin-screw extruder. Wettability considerations suggest that the filler unevenly distribute inside the material. This affect both the crystallinity of each phase and the blend microstructure. Controlling such phenomena can lead to highly "engineerized" materials with tailored properties. In particular, the typically poor mechanical performances of bio-based polymers can be overcame owing to the synergism among reinforcing action of the filler, its possible compatibilizing action and its impact on the crystallinity of the hosting phase.

  3. Fabrication of poly hydroxybutyrate-polyethylene glycol-folic acid nanoparticles loaded by paclitaxel.

    PubMed

    Rezaei, Fatemeh; Rafienia, Mohammad; Keshvari, Hamid; Sattary, Mansooreh; Naeimi, Mitra; Keyvani, Hossein

    2016-01-01

    In this study drug (paclitaxel)-loaded nanoparticles of poly hydroxybutyrate-polyethylene glycol-folic acid (PHB-PEG-FOL) were prepared by using an oil-in-water (O/W) emulsion-solvent evaporation method. The functionalization and conjugation steps in the chemical synthesis were confirmed using Fourier transform infrared (FTIR) and nuclear magnetic resonance tests ((1)H NMR). Morphology of nanoparticles was evaluated by scanning electron microscopy (SEM). Nanoparticles were characterized by particle size analyzer. Between two samples containing drug, the lower doses showed more homogeneous distribution, and the lowest aggregation. The drug release profiles showed a two-phase release including initial rapid release and a continuous release. MG63 cells were used to evaluate cytotoxicity. The cytotoxicity of PHB-PEG-FOL nanoparticles with drug against cancer cells was much higher and longer than free drug sample. These nanoparticles were successfully synthesized as a novel system for targeted drug delivery against cancer cells. PMID:26234551

  4. New poly(amino acid methacrylate) brush supports the formation of well-defined lipid membranes.

    PubMed

    Blakeston, Anita C; Alswieleh, Abdullah M; Heath, George R; Roth, Johannes S; Bao, Peng; Cheng, Nan; Armes, Steven P; Leggett, Graham J; Bushby, Richard J; Evans, Stephen D

    2015-03-31

    A novel poly(amino acid methacrylate) brush comprising zwitterionic cysteine groups (PCysMA) was utilized as a support for lipid bilayers. The polymer brush provides a 12-nm-thick cushion between the underlying hard support and the aqueous phase. At neutral pH, the zeta potential of the PCysMA brush was ∼-10 mV. Cationic vesicles containing >25% DOTAP were found to form a homogeneous lipid bilayer, as determined by a combination of surface analytical techniques. The lipid mobility as measured by FRAP (fluorescence recovery after photobleaching) gave diffusion coefficients of ∼1.5 μm(2) s(-1), which are comparable to those observed for lipid bilayers on glass substrates. PMID:25746444

  5. Mechanical and Electrical Characteristics of Poly-Lactic Acid which Added Plasticizer

    NASA Astrophysics Data System (ADS)

    Shinyama, Katsuyoshi; Fujita, Shigetaka

    Poly-lactic acid (PLA), a biodegradable plastic, has excellent electrical insulation properties. Being a hard resin, however, PLA is difficult to apply to coated cable. In this study, we blended a plasticizer with PLA to soften it, and examined the effects of the plasticizer on the mechanical and electrical characteristics of PLA. The glass transition temperature (Tg) and the melting point (Tm) had a tendency to decrease with an increase in the amount of plasticizer. With an increase in the amount of plasticizer, the tensile strength had a tendency to decrease and the breaking elongation to increase. As described above, PLA became softer with an increase in the amount of plasticizer. At 25°C, dielectric breakdown strength (EB) was about 5 MV/cm, irrespective of the presence of the plasticizer; the plasticizer showed almost no effect on EB. At 80°C, however, EB had a tendency to increase with an increase in the amount of plasticizer.

  6. Antimicrobial biomaterials based on carbon nanotubes dispersed in poly(lactic-co-glycolic acid)

    NASA Astrophysics Data System (ADS)

    Aslan, Seyma; Loebick, Codruta Zoican; Kang, Seoktae; Elimelech, Menachem; Pfefferle, Lisa D.; van Tassel, Paul R.

    2010-09-01

    Biomaterials that inactivate microbes are needed to eliminate medical device infections. We investigate here the antimicrobial nature of single-walled carbon nanotubes (SWNTs) incorporated within the biomedical polymer poly(lactic-co-glycolic acid) (PLGA). We find Escherichia coli and Staphylococcus epidermidis viability and metabolic activity to be significantly diminished in the presence of SWNT-PLGA, and to correlate with SWNT length and concentration (<2% by weight). Up to 98% of bacteria die within one hour on SWNT-PLGA versus 15-20% on pure PLGA. Shorter SWNTs are more toxic, possibly due to increased density of open tube ends. This study demonstrates the potential usefulness of SWNT-PLGA as an antimicrobial biomaterial.Biomaterials that inactivate microbes are needed to eliminate medical device infections. We investigate here the antimicrobial nature of single-walled carbon nanotubes (SWNTs) incorporated within the biomedical polymer poly(lactic-co-glycolic acid) (PLGA). We find Escherichia coli and Staphylococcus epidermidis viability and metabolic activity to be significantly diminished in the presence of SWNT-PLGA, and to correlate with SWNT length and concentration (<2% by weight). Up to 98% of bacteria die within one hour on SWNT-PLGA versus 15-20% on pure PLGA. Shorter SWNTs are more toxic, possibly due to increased density of open tube ends. This study demonstrates the potential usefulness of SWNT-PLGA as an antimicrobial biomaterial. Electronic supplementary information (ESI) available: Raman spectra before and after SWNT cutting via cyclodextrins, and sample images from viability and metabolic activity assays are included. See DOI: 10.1039/c0nr00329h

  7. Pluronic P85/poly(lactic acid) vesicles as novel carrier for oral insulin delivery.

    PubMed

    Xiong, Xiang Yuan; Li, Qi Han; Li, Yu Ping; Guo, Liang; Li, Zi Ling; Gong, Yan Chun

    2013-11-01

    Poly(lactic acid)-b-Pluronic-b-poly(lactic acid) (PLA-P85-PLA) vesicles were developed as novel carrier for oral insulin delivery. PLA-P85-PLA block copolymer was synthesized by ring opening polymerization of the monomer l-lactide using Pluronic copolymer P85 as the initiator. Insulin-loaded PLA-P85-PLA vesicles were prepared by dialysis method and the mean diameter of insulin-loaded PLA-P85-PLA vesicles was determined to be 178 nm. The cytotoxicity studies using human ovarian cancer cells OVCAR-3 indicate that PLA-P85-PLA block copolymer has good biocompatibility. Both in vitro and in vivo release behavior of insulin loaded in PLA-P85-PLA vesicles were studied. It was observed that insulin was released out gradually from PLA-P85-PLA vesicles and almost all insulin was released out 7.5h later. More importantly, for the oral administration of insulin-loaded PLA-P85-PLA vesicles at insulin doses of 200 IU/kg, the minimum blood glucose concentration was observed in the diabetic mice test after 2.5h, which was 15% of initial glucose level. Furthermore, the blood glucose concentration increased slowly to 31.8% of initial blood glucose concentration after 10.5h and was maintained at this level for at least an additional 14h (32.5% of initial blood glucose concentration at 24.5h). These results proved that PLA-P85-PLA vesicles could be promising polymeric carriers for oral insulin delivery application due to their sustained and enhanced hypoglycemic effect. PMID:23838194

  8. Preventing corona effects: multiphosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles.

    PubMed

    Torrisi, V; Graillot, A; Vitorazi, L; Crouzet, Q; Marletta, G; Loubat, C; Berret, J-F

    2014-08-11

    When dispersed in biological fluids, engineered nanoparticles are selectively coated with proteins, resulting in the formation of a protein corona. It is suggested that the protein corona is critical in regulating the conditions of entry into the cytoplasm of living cells. Recent reports describe this phenomenon as ubiquitous and independent of the nature of the particle. For nanomedicine applications, however, there is a need to design advanced and cost-effective coatings that are resistant to protein adsorption and that increase the biodistribution in vivo. In this study, phosphonic acid poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide particles. The copolymer composition was optimized to provide simple and scalable protocols as well as long-term stability in culture media. It is shown that polymers with multiple phosphonic acid functionalities and PEG chains outperform other types of coating, including ligands, polyelectrolytes, and carboxylic acid functionalized PEG. PEGylated particles exhibit moreover exceptional low cellular uptake, of the order of 100 femtograms of iron per cell. The present approach demonstrates that the surface chemistry of engineered particles is a key parameter in the interactions with cells. It also opens up new avenues for the efficient functionalization of inorganic surfaces. PMID:25046557

  9. Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

    NASA Astrophysics Data System (ADS)

    Seo, Hyun Suk; Ko, Yeong Mu; Shim, Jae Won; Lim, Yun Kyong; Kook, Joong-Ki; Cho, Dong-Lyun; Kim, Byung Hoon

    2010-11-01

    Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH2 of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.

  10. Poly(o-aminophenol)-modified bienzyme carbon paste electrode for the detection of uric acid.

    PubMed

    Miland, E; Miranda Ordieres, A J; Tuñón Blanco, P; Smyth, M R; Fágáin, C O

    1996-05-01

    A reagentless uric acid selective biosensor constructed by immobilising uricase and horseradish peroxidase (HRP) in carbon paste without the addition of an electron transfer mediator is described. The response of the electrode is based on the enzymatic reduction of hydrogen peroxide in the presence of uric acid. Uricase and HRP were dispersed in the carbon paste and the optimum paste mixture was determined. Poly(o-aminophenol) was electropolymerised at the working surface area of the electrode acting as a conducting polymer layer. Cyclic voltammetry was used to characterise the permselective characteristics of the polymer layer. At an applied potential of 50 mV vs. Ag/AgCl, a linear response was obtained up to 1 x 10(-4) M, with a limit of detection of 3 x 10(-6) M. The sensor had a response time of 37 s. a calibration precision of 2.2% (n = 4) and an estimated sample frequency of 20 h(-1). Responses to the analyte of interest were pH dependent. The sensor was incorporated into a flow injection system for the qualification of uric acid in human serum. Results compared favourably with a standard spectrophotometric method. PMID:18966549

  11. pH-Responsive Behavior of Poly(acrylic acid) Brushes of Varying Thickness

    NASA Astrophysics Data System (ADS)

    Yadav, Vivek; Robertson, Megan; Conrad, Jacinta

    2015-03-01

    We have investigated the pH-dependent response of polyelectrolyte brushes of varying thickness. Our model system consists of poly(acrylic acid) brushes, which change from hydrophobic and neutral at low pH to hydrophilic and negatively charged at high pH, synthesized using a grafting-from approach at constant grafting density. As the polymer brush thickness increased, the brushes exhibited greater hysteresis in static water contact angle as a function of pH. We extracted the pKa of the polymer brushes from contact angle measurements. The relationship between the pKa and brush thickness depended on the order in which the brushes were exposed to solutions of varying pH: pKa decreased on increasing brush thickness when going from basic to acidic medium whereas pKa increased on increasing brush thickness when going from acidic to basic medium. We speculate that the origin of hysteresis can be explained by pH-dependent conformational changes in these polyelectrolyte brushes.

  12. Microbial synthesis of poly-γ-glutamic acid: current progress, challenges, and future perspectives.

    PubMed

    Luo, Zhiting; Guo, Yuan; Liu, Jidong; Qiu, Hua; Zhao, Mouming; Zou, Wei; Li, Shubo

    2016-01-01

    Poly-γ-glutamic acid (γ-PGA) is a naturally occurring biopolymer made from repeating units of l-glutamic acid, d-glutamic acid, or both. Since some bacteria are capable of vigorous γ-PGA biosynthesis from renewable biomass, γ-PGA is considered a promising bio-based chemical and is already widely used in the food, medical, and wastewater industries due to its biodegradable, non-toxic, and non-immunogenic properties. In this review, we consider the properties, biosynthetic pathway, production strategies, and applications of γ-PGA. Microbial biosynthesis of γ-PGA and the molecular mechanisms regulating production are covered in particular detail. Genetic engineering and optimization of the growth medium, process control, and downstream processing have proved to be effective strategies for lowering the cost of production, as well as manipulating the molecular mass and conformational/enantiomeric properties that facilitate screening of competitive γ-PGA producers. Finally, future prospects of microbial γ-PGA production are discussed in light of recent progress, challenges, and trends in this field. PMID:27366207

  13. Polyaniline/poly acid acrylic thin film composites: a new gamma radiation detector

    SciTech Connect

    Lima Pacheco, Ana P.; Araujo, Elmo S.; Azevedo, Walter M. de

    2003-03-15

    In this paper, we present a new and straightforward route to prepare polyaniline/poly acid acrylic (PAA) thin film composites in large areas and on almost any surface. This method was developed to improve the mechanical and adherence properties of polyaniline devices used as ionization radiation sensors. The route consists of the combination of the metal oxidant with polymer acid to form a highly homogeneous and viscous paste, which can be easily spread over any surface. In the second step, an aniline acid solution is brought in contact with the dried paste where polymerization occurs, yielding a high homogeneous and conducting polymer composite. The UV-visible absorption and infrared analysis confirm that a polyaniline/PAA complex is obtained. The four-point conductivity measurements show that the composite conductivity {rho} is the order of 5 {omega}{sup -1} cm{sup -1}. Preliminary gamma radiation interaction with the composite shows that the doped composite exhibits a linear response that can be used in the development of real-time radiation sensors for the dose range from 0 to 5000 Gy.

  14. A stencil printed, high energy density silver oxide battery using a novel photopolymerizable poly(acrylic acid) separator.

    PubMed

    Braam, Kyle; Subramanian, Vivek

    2015-01-27

    A novel photopolymerized poly(acrylic acid) separator is demonstrated in a printed, high-energy-density silver oxide battery. The printed battery demonstrates a high capacity of 5.4 mA h cm(-2) at a discharge current density of 2.75 mA cm(-2) (C/2 rate) while delivering good mechanical flexibility and robustness. PMID:25475759

  15. Draft Genome Sequence of Bacillus subtilis subsp. natto Strain CGMCC 2108, a High Producer of Poly-γ-Glutamic Acid

    PubMed Central

    Tan, Siyuan; Su, Anping; Zhang, Chen; Ren, Yuanyuan

    2016-01-01

    Here, we report the 4.1-Mb draft genome sequence of Bacillus subtilis subsp. natto strain CGMCC 2108, a high producer of poly-γ-glutamic acid (γ-PGA). This sequence will provide further help for the biosynthesis of γ-PGA and will greatly facilitate research efforts in metabolic engineering of B. subtilis subsp. natto strain CGMCC 2108. PMID:27231363

  16. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/ polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study poly(lactic acid)(PLA) and polyvinylpyrrolidone (PVP) micro and nanofibers mats loaded with copaiba (Copaifera sp.) oil were produced by solution blow spinning (SBS). The copaiba (Copaifera sp.) oil was characterized by gas chromatography (GC). Neat PLA and four PLA/ PVP blends contain...

  17. Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance.

    PubMed

    Shirazi, Reyhaneh Neghabat; Aldabbagh, Fawaz; Ronan, William; Erxleben, Andrea; Rochev, Yury; McHugh, Peter

    2016-10-01

    In this study, the effects of material thickness and processing method on the degradation rate and the changes in the mechanical properties of poly(lactic-co-glycolic acid) material during simulated physiological degradation were investigated. Two types of poly(lactic-co-glycolic acid) materials were considered: 0.12 mm solvent-cast films and 1 mm compression-moulded plates. The experimental results presented in this study were compared to the experimental results of Shirazi et al. (Acta Biomaterialia 10(11):4695-703, 2014) for 0.25 mm solvent-cast films. These experimental observations were used to validate the computational modelling predictions of Shirazi et al. (J Mech Behav Biomed Mater 54: 48-59, 2016) on critical diffusion length scale and also to refine the model parameters. The specific material processing methods considered here did not have a significant effect on the degradation rate and the changes in mechanical properties during degradation; however, they influenced the initial molecular weight and they determined the stiffness and hardness of the poly(lactic-co-glycolic acid) material. The experimental observations strongly supported the computational modelling predictions that showed no significant difference in the degradation rate and the changes in the elastic modulus of poly(lactic-co-glycolic acid) films for thicknesses larger than 100 μm. PMID:27590824

  18. Thermal Properties of Extruded Injection-Molded Poly (lactic acid) and Milkweed Composites: Degradation Kinectics and Enthalpic Relaxation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to determine the degree of compatibility between Poly (lactic Acid) (PLA) and different biomaterials, PLA was compounded with milkweed fiber, a new crop oil seed. After oil extraction, the remaining cake retained approximately 10% residual oil and 47% protein. The pressed seed cake (10% mo...

  19. Stereoregularity of poly (lactic acid) and their model compounds as studied by NMR and quantum chemical calculations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to understand the origin of the tacticity splitting in the NMR spectrum of poly(lactic acid), monomer model compound and dimer model compounds (both isotactic and syndiotactic) were synthesized and their 1H and 13C NMR chemical shifts observed. Two energetically stable conformations were o...

  20. Thermal properties of extruded injection-molded poly (lactic acid) and milkweed composites: degradation kinetics and enthalpic relaxation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...