WorldWideScience

Sample records for biodegradable polylactic acid

  1. Biodegradation of high molecular weight polylactic acid

    OpenAIRE

    Stloukal, Petr; Koutný, Marek; Sedlařík, Vladimír; Kucharczyk, Pavel

    2012-01-01

    Polylactid acid seems to be an appropriate replacement of conventional non-biodegradable synthetic polymer primarily due to comparable mechanical, thermal and processing properties in its high molecular weight form. Biodegradation of high molecular PLA was studied in compost for various forms differing in their specific surface area. The material proved its good biodegradability under composting conditions and all investigated forms showed to be acceptable for industrial composting. Despite e...

  2. Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging

    Science.gov (United States)

    Biodegradable polylactic acid (PLA) polymer was evaluated for its application as a material for antimicrobial food packaging. PLA films were incorporated with nisin to provide slow release of the encapsulated antimicrobial for control of foodborne pathogens. Antimicrobial activity of PLA/nisin films...

  3. Effect of an acid filler on hydrolysis and biodegradation of poly-lactic acid (PLA)

    Science.gov (United States)

    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.

  4. Biodegradability of injection molded bioplastic pots containing polylactic acid and poultry feather fiber.

    Science.gov (United States)

    Ahn, H K; Huda, M S; Smith, M C; Mulbry, W; Schmidt, W F; Reeves, J B

    2011-04-01

    The biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 °C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was very low (13 ± 3%) compared to literature values for other PLA materials. Near infrared spectroscopy (NIRS) results suggest that the PLA undergoes chemical structural changes during polymer extrusion and injection molding. These changes may be the basis of the low biodegradability value. Biodegradability of pot types B (containing 5% poultry feather, 80% PLA, 15% starch), and C (containing 50% poultry feather, 25% urea, 25% glycerol), were 53 ± 2% and 39 ± 3%, respectively. More than 85% of the total biodegradation of these bioplastics occurred within 38 days. NIRS results revealed that poultry feather was not degraded during composting. PMID:21320772

  5. Biodegradation of poly(lactic acid) and some of its based systems with Trichoderma viride.

    Science.gov (United States)

    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

  6. Biodegradable Polylactic Acid (PLA) Microstructures for Scaffold Applications

    CERN Document Server

    Wang, G -J; Hsueh, C -C

    2008-01-01

    In this research, we present a simple and cost effective soft lithographic process to fabricate PLA scaffolds for tissue engineering. In which, the negative photoresist JSR THB-120N was spun on a glass subtract followed by conventional UV lithographic processes to fabricate the master to cast the PDMS elastomeric mold. A thin poly(vinyl alcohol) (PVA) layer was used as a mode release such that the PLA scaffold can be easily peeled off. The PLA precursor solution was then cast onto the PDMS mold to form the PLA microstructures. After evaporating the solvent, the PLA microstructures can be easily peeled off from the PDMS mold. Experimental results show that the desired microvessels scaffold can be successfully transferred to the biodegradable polymer PLA.

  7. Biodegradable poly(lactic acid) microspheres containing total alkaloids of Caulis sinomenii

    Indian Academy of Sciences (India)

    Wen Zhang; Xiaojie Lin; Xingxiang Zhang

    2011-12-01

    The fabrication of biodegradable poly(lactic acid) (PLA) microspheres containing total alkaloids of Caulis sinomenii was investigated. The formation, diameter, morphology and properties of the microspheres were characterized using Fourier transform infrared spectroscopy (FT–IR), laser particle size analyser and scanning electron microscopy (SEM), etc. In vitro releasing behaviour was also investigated using UV-Vis spectrometer. As a result, the drug-loaded microspheres with a narrower distributive, rounder and smoother surface were prepared. Drug-releasing behaviour from microspheres was affected by the concentration of emulsifier and the stirring rate. The results demonstrated that a medicated system, which can be potentially applied within a drug delivery system, was designed. This system acts in a systematic manner for the treatment of rheumatoid arthritis.

  8. Disposal Options of Bamboo Fabric-Reinforced Poly(Lactic) Acid Composites for Sustainable Packaging: Biodegradability and Recyclability

    OpenAIRE

    M.R. Nurul Fazita; Krishnan Jayaraman; Debes Bhattacharyya; Md. Sohrab Hossain; Mohamad Haafiz, M. K.; Abdul Khalil H.P.S.

    2015-01-01

    The present study was conducted to determine the recyclability and biodegradability of bamboo fabric-reinforced poly(lactic) acid (BF-PLA) composites for sustainable packaging. BF-PLA composite was recycled through the granulation, extrusion, pelletization and injection processes. Subsequently, mechanical properties (tensile, flexural and impact strength), thermal stability and the morphological appearance of recycled BF-PLA composites were determined and compared to BF-PLA composite (initial...

  9. Weathering and Biodegradation Study on Graft Copolymer Compatibilized Hybrid Bionanocomposites of Poly(Lactic Acid)

    Science.gov (United States)

    Sajna, VP; Nayak, Sanjay K.; Mohanty, Smita

    2016-06-01

    This work reports on the influence of moisture absorption and accelerated weathering on the properties of graft copolymer compatibilized bionanocomposites of poly(lactic acid) (PLA). Moisture absorption tests were conducted for 30 days by immersing the samples in a distilled water bath at room temperature, and the amount of moisture absorbed in each time interval was measured. The rate of moisture uptake decreased by incorporation of C30B nanoclay and graft copolymer into fiber-reinforced PLA composites. Changes in the mechanical properties of composites in each time interval of moisture absorption were investigated using tensile and impact tests. Exposure to moisture caused significant drops in the mechanical properties. The morphological characterization of biocomposites during the aforementioned tests has been made using SEM, while bionanocomposites were analyzed by TEM. Further, this paper also reported the effect of accelerated weathering on the mechanical properties and the results are confirmed through SEM analysis. Biodegradation behaviors of PLA biocomposites and bionanocomposites have also been studied.

  10. Weathering and Biodegradation Study on Graft Copolymer Compatibilized Hybrid Bionanocomposites of Poly(Lactic Acid)

    Science.gov (United States)

    Sajna, VP; Nayak, Sanjay K.; Mohanty, Smita

    2016-07-01

    This work reports on the influence of moisture absorption and accelerated weathering on the properties of graft copolymer compatibilized bionanocomposites of poly(lactic acid) (PLA). Moisture absorption tests were conducted for 30 days by immersing the samples in a distilled water bath at room temperature, and the amount of moisture absorbed in each time interval was measured. The rate of moisture uptake decreased by incorporation of C30B nanoclay and graft copolymer into fiber-reinforced PLA composites. Changes in the mechanical properties of composites in each time interval of moisture absorption were investigated using tensile and impact tests. Exposure to moisture caused significant drops in the mechanical properties. The morphological characterization of biocomposites during the aforementioned tests has been made using SEM, while bionanocomposites were analyzed by TEM. Further, this paper also reported the effect of accelerated weathering on the mechanical properties and the results are confirmed through SEM analysis. Biodegradation behaviors of PLA biocomposites and bionanocomposites have also been studied.

  11. Biodegradable poly(lactic acid)/.epsilon. - polycaprolactone (PLA/PCL) blends: interfacial tension estimates

    Czech Academy of Sciences Publication Activity Database

    Jůza, Josef; Mikešová, Jana; Ostafinska, Aleksandra; Michálková, Danuše; Fortelný, Ivan

    Prague: Institute of Macromolecular Chemistry AS CR, 2015. s. 63. ISBN 978-80-85009-82-8. [Functional Polymers at Bio-Material Interfaces - 79th Prague Meeting on Macromolecules. 28.06.2015-02.07.2015, Prague] Institutional support: RVO:61389013 Keywords : poly(lactic acid) * polycaprolactone * interfacial tension Subject RIV: CD - Macromolecular Chemistry

  12. Disposal Options of Bamboo Fabric-Reinforced Poly(Lactic Acid Composites for Sustainable Packaging: Biodegradability and Recyclability

    Directory of Open Access Journals (Sweden)

    M.R. Nurul Fazita

    2015-08-01

    Full Text Available The present study was conducted to determine the recyclability and biodegradability of bamboo fabric-reinforced poly(lactic acid (BF-PLA composites for sustainable packaging. BF-PLA composite was recycled through the granulation, extrusion, pelletization and injection processes. Subsequently, mechanical properties (tensile, flexural and impact strength, thermal stability and the morphological appearance of recycled BF-PLA composites were determined and compared to BF-PLA composite (initial materials and virgin PLA. It was observed that the BF-PLA composites had the adequate mechanical rigidity and thermal stability to be recycled and reused. Moreover, the biodegradability of BF-PLA composite was evaluated in controlled and real composting conditions, and the rate of biodegradability of BF-PLA composites was compared to the virgin PLA. Morphological and thermal characteristics of the biodegradable BF-PLA and virgin PLA were obtained by using environment scanning electron microscopy (ESEM and differential scanning calorimetry (DSC, respectively. The first order decay rate was found to be 0.0278 and 0.0151 day−1 in a controlled composting condition and 0.0008 and 0.0009 day−1 in real composting conditions for virgin PLA and BF-PLA composite, respectively. Results indicate that the reinforcement of bamboo fabric in PLA matrix minimizes the degradation rate of BF-PLA composite. Thus, BF-PLA composite has the potential to be used in product packaging for providing sustainable packaging.

  13. Polylactic acid coating on a biodegradable magnesium alloy: An in vitro degradation study by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alabbasi, Alyaa; Liyanaarachchi, S.; Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au

    2012-09-30

    Polylactic acid (PLA) was coated on a biodegradable magnesium alloy, AZ91, using spin coating technique for temporary implant applications. The degradation behaviour of the coated alloy samples was evaluated using electrochemical impedance spectroscopy (EIS) method in simulated body fluid (SBF). EIS results suggested that the PLA coating enhanced the degradation resistance of the alloy significantly. Increase in the PLA coating thickness was found to increase the degradation resistance, but resulted in poor adhesion. Long-term EIS experiments of the PLA coated samples suggested that their degradation resistance gradually decreased with increase in SBF exposure time. However, the degradation resistance of the PLA coated samples was significantly higher than that of the bare metal even after a 48 h exposure to SBF. - Highlights: Black-Right-Pointing-Pointer Polylactic acid (PLA) was coated on a magnesium-based alloy. Black-Right-Pointing-Pointer PLA coating enhanced the in vitro degradation resistance of the alloy. Black-Right-Pointing-Pointer Increase in the PLA coating thickness improved the alloy degradation resistance. Black-Right-Pointing-Pointer Thin film PLA coating exhibited both good degradation resistance and adhesion.

  14. Polylactic acid coating on a biodegradable magnesium alloy: An in vitro degradation study by electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Polylactic acid (PLA) was coated on a biodegradable magnesium alloy, AZ91, using spin coating technique for temporary implant applications. The degradation behaviour of the coated alloy samples was evaluated using electrochemical impedance spectroscopy (EIS) method in simulated body fluid (SBF). EIS results suggested that the PLA coating enhanced the degradation resistance of the alloy significantly. Increase in the PLA coating thickness was found to increase the degradation resistance, but resulted in poor adhesion. Long-term EIS experiments of the PLA coated samples suggested that their degradation resistance gradually decreased with increase in SBF exposure time. However, the degradation resistance of the PLA coated samples was significantly higher than that of the bare metal even after a 48 h exposure to SBF. - Highlights: ► Polylactic acid (PLA) was coated on a magnesium-based alloy. ► PLA coating enhanced the in vitro degradation resistance of the alloy. ► Increase in the PLA coating thickness improved the alloy degradation resistance. ► Thin film PLA coating exhibited both good degradation resistance and adhesion.

  15. Novel ultrasound contrast agents--Biodegradable poly(lactic acid) microcapsules

    Institute of Scientific and Technical Information of China (English)

    王身国; 崔文瑾; 李光明; 蔡晴; 智光; 赵玉英; 杨波; 徐勇

    2003-01-01

    As a novel ultrasound diagnostic contrast agent, the preparation, characterization and ultrasound imaging in the body of dog about poly(lactic acid) (PLLA) microcapsules have been studied. The behavior of this kind of contrast agent in the microcirculation was also investigated. Prepared by (water/oil/water) emulsion-solvent evaporation protocol, the PLLA microcapsules with hollow structure can enhance the ultrasound image both in vitro and in vivo, and the enduring time can last as long as 3 h. The microcirculation examination shows that the PLLA microcapsules with a diameter ranging from 2 to 8 μm could pass through the pulmonary capillaries without retention. All the results prove the PLLA microcapsules for potential use for the clinical application.

  16. Preparation of biodegradable magnetic microspheres with poly(lactic acid)-coated magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Hong; Saatchi, Katayoun [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, 6T 1Z3 (Canada); Haefeli, Urs O. [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3 (Canada)], E-mail: uhafeli@interchange.ubc.ca

    2009-05-15

    Poly(lactic acid) (PLA)-coated magnetic nanoparticles were made using uncapped PLA with free carboxylate groups. The physical properties of these particles were compared to those of oleate-coated or oleate/sulphonate bilayer (W40) coated magnetic particles. Magnetic microspheres (MMS) with the matrix material poly(lactide-co-glycolide) (PLGA) or PLA were then formed by the emulsion solvent extraction method with encapsulation efficiencies of 40%, 83% and 96% for oleate, PLA and oleate/sulfonate-coated magnetic particles, respectively. MMS made from PLA-coated magnetite were hemocompatible and produced no hemolysis, whereas the other MMS were hemolytic above 0.3 mg/mL of blood.

  17. Preparation of biodegradable magnetic microspheres with poly(lactic acid)-coated magnetite

    International Nuclear Information System (INIS)

    Poly(lactic acid) (PLA)-coated magnetic nanoparticles were made using uncapped PLA with free carboxylate groups. The physical properties of these particles were compared to those of oleate-coated or oleate/sulphonate bilayer (W40) coated magnetic particles. Magnetic microspheres (MMS) with the matrix material poly(lactide-co-glycolide) (PLGA) or PLA were then formed by the emulsion solvent extraction method with encapsulation efficiencies of 40%, 83% and 96% for oleate, PLA and oleate/sulfonate-coated magnetic particles, respectively. MMS made from PLA-coated magnetite were hemocompatible and produced no hemolysis, whereas the other MMS were hemolytic above 0.3 mg/mL of blood.

  18. Biodegradable Poly(Lactic Acid/Multiwalled Carbon Nanotube Nanocomposite Fabrication Using Casting And Hot Press Techniques

    Directory of Open Access Journals (Sweden)

    Park S.G.

    2015-06-01

    Full Text Available Biodegradable advanced polymer composites have recently received a large amount of attention. The present study aimed to design poly(lactic acid multiwalled carbon nanotube nanocomposites (PLA/MWCNTs using a simple fabrication technique. A PLA sheet was first dissolved in dichloromethane, and MWCNTs were subsequently added at various concentrations (0.5, 1.5 and 5% while applying shear strain stirring to achieve dispersion of carbon nanotubes (CNTs. These solutions were then molded and a hot press was used to generate sheets free of voids with entrapped solvent. The prepared samples were characterized using field emission scanning electron microscopy (FE-SEM, x-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, and thermogravimetric analysis (TGA. Our data showed composite samples free of defects and voids, indicating that the hot press is capable of generating sufficiently compact polymer matrices. Additionally, TGA and FTIR showed significant bonding interactions between the PLA matrix and the nano-fillers. Collectively, our results suggest that incorporation of CNTs as nano-fillers into biodegradable polymers may have multiple applications in many different sectors.

  19. Biodegradation of thermoplastic starch and its blends with poly(lactic acid) and polyethylene: influence of morphology

    Science.gov (United States)

    The room temperature mineralization of thermoplastic starch (TPS) with a high glycerol content and its blends with low-density polyethylene (LDPE) and polylactic acid (PLA) are examined under controlled degradation conditions. These results are correlated with the morphologies and continuity behavio...

  20. Biodegradation of poly(lactic acid), poly(hydroxybutyrate-co-hydroxyvalerate), poly(butylene succinate) and poly(butylene adipate-co-terephthalate) under anaerobic and oxygen limited thermophilic conditions

    OpenAIRE

    Jutakan Boonmee; Charnwit Kositanont; Thanawadee Leejarkpai

    2016-01-01

    In order to study the biodegradation behavior of biodegradable plastics in landfill conditions, four types of biodegradable plastics including poly(lactic acid) (PLA), poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), poly(butylene succinate) (PBS), and poly(butylene adipate-co-terephthalate) (PBAT) were tested by burying in sludge mixed soil medium under anaerobic and oxygen limited conditions. The experiments were operated at 52 ± 2ºC in dark conditions according to ISO15985. The degree of b...

  1. Usefulness of biodegradable stents constructed of poly-/-lactic acid monofilaments in patients with benign esophageal stenosis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To report 13 patients with benign esophageal stenosis treated with the biodegradable stent.METHODS: We developed a Ultraflex-type stent by knitting poly-l-lactic acid monofilaments.RESULTS: Two cases were esophageal stenosis caused by drinking of caustic liquid, 4 cases were due to surgical resection of esophageal cancers, and 7 cases were patients with esophageal cancer who received the preventive placement of biodegradable stents for postendoscopic mucosal dissection (ESD) stenosis. The preventive placement was performed within 2 to 3 d after ESD. In 10 of the 13 cases, spontaneous migration of the stents occurred between 10 to 21 d after placement. In these cases, the migrated stents were excreted with the feces, and no obstructive complications were experienced. In 3 cases, the stents remained at the proper location on d 21 after placement. No symptoms of re-stenosis were observed within the follow-up period of 7 mo to 2 years. Further treatment with balloon dilatation or replacement of the biodegradable stent was not required.CONCLUSION: Biodegradable stents were useful for the treatment of benign esophageal stenosis, particularly for the prevention of post-ESD stenosis.

  2. Green chemical synthesis of poly(lactic acid) based biodegradable polymers%聚乳酸降解材料的绿色化学合成

    Institute of Scientific and Technical Information of China (English)

    许文殊; 罗祥林

    2011-01-01

    背景:聚乳酸具有良好的生物相容性和生物降解性,广泛应用于药物缓释、手术缝合线、组织工程支架及骨修复材料等生物医用领域.但其常规合成方法需使用溶剂,生产效率较低且成本较高.目的:对非溶剂的绿色化学方法-乳酸熔融缩聚/二异氰酸酯熔融扩链,合成聚乳酸降解材料的研究进展进行综述.方法:应用计算机检索SCI-Expanded数据库(1995-01/2010-06),以"Poly(lactic acid),diisocyanate"为检索词;应用计算机检索中国期刊网络出版总库(1999-01/2010-06),以"聚乳酸,异氰酸酯"为检索词.共收集130篇关于乳酸熔融缩聚/二异氰酸酯熔融扩链的文献,中文39篇,英文91篇.排除发表内容重复、实验结果较差的文献,共32篇文献符合标准被纳入.结果与结论:采用非溶剂的绿色化学方法-乳酸熔融缩聚/二异氰酸酯熔融扩链,通过改变异氰酸酯和预聚物的种类和比例,就可以制备具有不同相对分子质量和性能的可降解聚乳酸基聚氨酯材料,有望在生物医用领域和日常生活中取得实际的应用.%BACKGROUND: Poly(lactic acid) has excellent biocompatibility and biodegradability, thus it has been widely used in many biomedical fields, such as drug delayed release, surgical suture, tissue engineering scaffold and bone substitutes. Routine synthesis requires the use of solvent, showing low production efficacy and high cost.OBJECTIVE: Non-solvent green chemical synthesis of poly(lactic acid) based biodegradable materials via direct condensation polymerization and chain extension in melt state were reviewed.METHODS: A computer-based online search of SCI-Expanded database (1995-01/2010-06) and China Academic Journal Network Publishing Database was performed for related articles with the key words of "poly (lactic acid), diisocyanate" in English and in Chinese. A total of 130 articles regarding the lactic acid polycondensation/diisocyanate chain extension in melt

  3. Melt Free-Radical Grafting of Maleic Anhydride onto Biodegradable Poly(lactic acid by Using Styrene as A Comonomer

    Directory of Open Access Journals (Sweden)

    Piming Ma

    2014-05-01

    Full Text Available Maleic anhydride (MA was grafted onto poly(lactic acid (PLA in the presence of styrene (St by using a free-radical grafting methodology. The grafting degree (Dg of MA was increased from 0.65 wt % to 1.1 wt % with the St/MA ratio up to 2/1, where the grafting efficiency (Eg of MA was 27%. However, both Dg and Eg were decreased with further increasing of the St/MA ratio to 4/1. The Dg of MA increased with MA concentration and showed a maximum at 180 °C in the temperature range of 165 °C–190 °C. The grafting mechanisms of MA in the presence of St are analyzed based on titration, thermogravimetric analysis and infrared results, i.e., MA is grafted onto PLA chains via single monomers and a charge-transfer-complex (CTC at St/MA ratios of ≤ 1/1, while dominantly via St-co-MA oligomers at St/MA ratios of around 2/1. Copolymerization rather than grafting of St and MA occurs at St/MA ratios of around 4/1. The thermal stability of PLA was compromised to a certain extent by the grafting of MA, resulting in reductions in the decomposition temperature (Td-5% and molecular weight of the PLA. In addition, the crystallization and melting temperatures of the PLA were slightly reduced after the grafting.

  4. Mechanical properties and morphology of biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate) blends compatibilized by transesterification

    International Nuclear Information System (INIS)

    Highlights: ► Compatibility between PLA and PBAT is improved through transesterification. ► Elongation at break of PLA was up to almost 300%. ► Both toughness and stiffness of PLA/PBAT blends are improved significantly after the incorporation of TBT. -- Abstract: Biodegradable poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends with various tetrabutyl titanate (TBT) concentration were prepared through melt-extrusion. Mechanical properties and morphology were characterized in terms of tensile and impact testing, dynamical mechanical analysis and scanning electron micrograph (SEM). The results indicated that the overall mechanical properties (including tensile strength, elongation at break, toughness and stiffness) of PLA/PBAT blends can be improved significantly after the incorporation of TBT. The SEM micrographs demonstrated that the compatibility and strong interaction between PLA and PBAT was improved via transesterification during melt-extrusion. The interfacial debonding, pullout of PBAT, yielding deformation were the most important mechanisms to improve toughness.

  5. Tailoring of catalytic routes towards high performance polylactic acid polymers.

    OpenAIRE

    Dusselier, Michiel

    2013-01-01

    Renewable polymers offer a promising alternative for certain fossil fuel derived plastics and harness potential as well in specialty applications. One of the top 3 polymers in this respect is polylactic acid (PLA). Next to its renewable origin Â# sugars, abundantly encountered in food crops but also in non-edible cellulose Â# PLA is biocompatible and biodegradable. These unique features render this polymer suitable for many custom applications, for instance in medicine (prostheses, drug deliv...

  6. Sandwich-Architectured Poly(lactic acid)-Graphene Composite Food Packaging Films

    NARCIS (Netherlands)

    Goh, Kunli; Heising, Jenneke K.; Yuan, Yang; Karahan, Huseyin E.; Wei, Li; Zhai, Shengli; Koh, Jia Xuan; Htin, Nanda M.; Zhang, Feimo; Wang, Rong; Fane, Anthony G.; Dekker, Matthijs; Dehghani, Fariba; Chen, Yuan

    2016-01-01

    Biodegradable food packaging promises a more sustainable future. Among the many different biopolymers used, poly(lactic acid) (PLA) possesses the good mechanical property and cost-effectiveness necessary of a biodegradable food packaging. However, PLA food packaging suffers from poor water vapor

  7. Biodegradation of poly(lactic acid, poly(hydroxybutyrate-co-hydroxyvalerate, poly(butylene succinate and poly(butylene adipate-co-terephthalate under anaerobic and oxygen limited thermophilic conditions

    Directory of Open Access Journals (Sweden)

    Jutakan Boonmee

    2016-01-01

    Full Text Available In order to study the biodegradation behavior of biodegradable plastics in landfill conditions, four types of biodegradable plastics including poly(lactic acid (PLA, poly(hydroxybutyrate-co-hydroxyvalerate (PHBV, poly(butylene succinate (PBS, and poly(butylene adipate-co-terephthalate (PBAT were tested by burying in sludge mixed soil medium under anaerobic and oxygen limited conditions. The experiments were operated at 52 ± 2ºC in dark conditions according to ISO15985. The degree of biodegradation after 75 days was investigated by weight loss determination, visual examination, and surface appearance by scanning electronic microscopy (SEM. Under both anaerobic and oxygen limited conditions, the complete degradation (100% weight loss was found only in PHBV after 75 days. The plastic degradations were ranked in the order of PHBV> PLA> PBS> PBAT. The percentage of weight losses were significantly different at p ≤ 0.05. However, for all studied plastics, the degradation under anaerobic and oxygen limited conditions did not significantly different at 95% confidence.

  8. 绿色塑料聚乳酸的关键技术研发与产业化应用%Key Technology R & D and Industrial Applications of Biodegradable Plastics Polylactic Acid

    Institute of Scientific and Technical Information of China (English)

    陈学思

    2015-01-01

    As a new bio-based green plastic, polylactic acid (PLA) can be widely used in various ifelds. It can provide strong material support to solve environmental pollution and oil dependence. For the current existence of key scientiifc and technical problems in polylactic acid industry, CAS Changchun Institute of Applied Chemistry carry out innovative projects to promote development and application of key technologies of biological polylactic acid green plastic industrialization. It makes a breakthrough of a series of key technical problems on L-lactic acid, lactic acid oligomerization break, cracking, reifning and lactide ring-opening polymerization and makes a series of innovative achievements. It achieved the world's second large-scale production and application of PLA after the US and accelerate the polylactic acid as the leading biodegradable plastics industry development. This article reviews the importance of polylactic key technology development and industrialization projects and the good results which has achieved. It put forward some suggestions of polylactic acid for industrial development in China.%聚乳酸(PLA)作为一种新型生物基绿色塑料,能够广泛应用于多种领域,为解决环境污染和石油依赖等问题提供有力的材料支撑。中国科学院长春应用化学研究所针对当前聚乳酸产业化存在的关键科学和技术性难题,开展了生物基聚乳酸绿色塑料产业化关键技术的创新性研发及应用推广项目,从L-乳酸出发,突破了乳酸低聚、裂解、丙交酯精制和开环聚合等一系列关键技术问题,取得了一系列创新性成果,在世界上继美国Nature Works后第二个实现了PLA规模化生产和应用,加速推动了以聚乳酸为龙头的生物可降解塑料行业的发展。本文综述了聚乳酸关键技术研发与产业化项目的重要意义,已取得的阶段性成果,并针对聚乳酸产业化在我国的发展提出了许多对策建议。

  9. Preclinical in vivo Performance of Novel Biodegradable, Electrospun Poly(lactic acid and Poly(lactic-co-glycolic acid Nanocomposites: A Review

    Directory of Open Access Journals (Sweden)

    Claudia Holderegger

    2015-08-01

    Full Text Available Bone substitute materials have witnessed tremendous development over the past decades and autogenous bone may still be considered the gold standard for many clinicians and clinical approaches in order to rebuild and restore bone defects. However, a plethora of novel xenogenic and synthetic bone substitute materials have been introduced in recent years in the field of bone regeneration. As the development of bone is actually a calcification process within a collagen fiber arrangement, the use of scaffolds in the formation of fibers may offer some advantages, along with additional handling characteristics. This review focuses on material characteristics and degradation behavior of electrospun biodegradable polyester scaffolds. Furthermore, we concentrated on the preclinical in vivo performance with regard to bone regeneration in preclinical studies. The major findings are as follows: Scaffold composition and architecture determine its biological behavior and degradation characteristics; The incorporation of inorganic substances and/or organic substances within composite scaffolds enhances new bone formation; L-poly(lactic acid and poly(lactic-co-glycolic acid composite scaffolds, especially when combined with basic substances like hydroxyapatite, tricalcium phosphate or demineralized bone powder, seem not to induce inflammatory tissue reactions in vivo.

  10. Effect of gamma ray on poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable food packaging films

    International Nuclear Information System (INIS)

    Poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] blends as new transparent film packaging materials were prepared at various blend compositions and different vinyl alcohol contents. The blends and pure PLA were irradiated by gamma rays to investigate the extent of changes in the packaging material during gamma ray sterilization process. The miscibility of the blends was dependent on the blend composition and vinyl alcohol content; gamma irradiation had little effect on the extent of miscibility. The glass transition temperature of pure PLA and PLA/P(VAc-co-VA) miscible blends reduced after irradiation. On the other hand in PLA/P(VAc-co-VA) immiscible blends, while the glass transition temperature of the PLA phase decreased; that of the copolymer phase slightly increased. The reduction in the glass transition was about 10 percent for samples irradiated with 50 kGy indicating dominance of chain scission of PLA molecules at high irradiation dose. The latter was verified by drop in mechanical properties of pure PLA after exposing to gamma irradiation at 50 kGy. Blending of PLA with the copolymer P(VAc-co-VA) compensated greatly the adverse effects of irradiation on PLA. The oxygen-barrier property of the blend was superior to the neat PLA and remained almost intact with irradiation. The un-irradiated and irradiated blends had excellent transparency. Gamma ray doses used for sterilization purposes are usually less than 20 kGy. It was shown that gamma irradiation at 20 kGy had no or little adverse effects on PLA/P(VAc-co-VA) blends mechanical and gas barrier properties. - Highlights: • Poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends were prepared as new packaging film. • The blends are superior to PLA in oxygen gas barrier property. • The blends are suitable for gamma ray sterilization and maintain useful mechanical properties. • The blends are perfectly transparent

  11. Poly(lactic acid) and Osage Orange Wood Fiber Composites for Agricultural Mulch Films

    Science.gov (United States)

    Osage orange wood(OO)was combined with poly(lactic acid)(PLA)to form a polymer composite intended for use as an agricultural mulch film. The PLA-OO mechanical properties were comparable to existing mulch film products and had the advantage of being completely biodegradable through a single growing ...

  12. GREEN COMPOSITES OF POLY(LACTIC ACID) AND OILSEED CO-PRODUCTS

    Science.gov (United States)

    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...

  13. POLY(LACTIC ACID) GREEN COMPOSITES USING OILSEED COPRODUCTS AS FILLERS

    Science.gov (United States)

    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. Poly(lactic acid) /kenaf fiber composites: effect of microfibrillated cellulose on interface-sensitive properties

    OpenAIRE

    Bogoeva-Gaceva, Gordana; Dimeski, Dimko; Srebrenkoska, Vineta

    2012-01-01

    Ecologically friendly composites consist of a biodegradable matrix and natural fibers (such as cotton, sisal, kenaf, bamboo, etc.), which have been successfully used for reinforcing of different polymer matrices. Quite recently, poly(lactic acid) (PLA) was used as a matrix for biodegradable eco-composites. Natural fibers (NFs) offer both cost savings and a reduction in density when compared to glass fibers. Though the strength of NFs is not as great as glass, the specific properti...

  15. Effect of gamma ray on poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable food packaging films

    Science.gov (United States)

    Razavi, Seyed Mohammad; Dadbin, Susan; Frounchi, Masoud

    2014-03-01

    Poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] blends as new transparent film packaging materials were prepared at various blend compositions and different vinyl alcohol contents. The blends and pure PLA were irradiated by gamma rays to investigate the extent of changes in the packaging material during gamma ray sterilization process. The miscibility of the blends was dependent on the blend composition and vinyl alcohol content; gamma irradiation had little effect on the extent of miscibility. The glass transition temperature of pure PLA and PLA/P(VAc-co-VA) miscible blends reduced after irradiation. On the other hand in PLA/P(VAc-co-VA) immiscible blends, while the glass transition temperature of the PLA phase decreased; that of the copolymer phase slightly increased. The reduction in the glass transition was about 10 percent for samples irradiated with 50 kGy indicating dominance of chain scission of PLA molecules at high irradiation dose. The latter was verified by drop in mechanical properties of pure PLA after exposing to gamma irradiation at 50 kGy. Blending of PLA with the copolymer P(VAc-co-VA) compensated greatly the adverse effects of irradiation on PLA. The oxygen-barrier property of the blend was superior to the neat PLA and remained almost intact with irradiation. The un-irradiated and irradiated blends had excellent transparency. Gamma ray doses used for sterilization purposes are usually less than 20 kGy. It was shown that gamma irradiation at 20 kGy had no or little adverse effects on PLA/P(VAc-co-VA) blends mechanical and gas barrier properties.

  16. Utilization of a Biodegradable Mulch Sheet Produced from Poly(Lactic Acid/Ecoflex®/Modified Starch in Mandarin Orange Groves

    Directory of Open Access Journals (Sweden)

    Yasukatsu Maeda

    2009-08-01

    Full Text Available We have developed a mulch sheet made by inflation molding of PLA, Ecoflex® and modified starch, which all have different biodegradabilities. A field test of use as an agricultural mulch sheet for mandarin oranges was carried out over two years. The mechanical properties of the mulch sheet were weakened with time during the field test, but the quality of the mandarin oranges increased, a result of the controlled degradation of the sheet. The most degradable modified starch degraded first, allowing control of the moisture on the soil. Accelerator mass spectroscopy was used for evaluation of the biomass carbon ratio. The biomass carbon ratio decreased by degradation of the biobased materials, PLA and modified starch in the mulch sheet.

  17. Lactide Synthesis and Chirality Control for Polylactic acid Production.

    Science.gov (United States)

    Van Wouwe, Pieter; Dusselier, Michiel; Vanleeuw, Evelien; Sels, Bert

    2016-05-10

    Polylactic acid (PLA) is a very promising biodegradable, renewable, and biocompatible polymer. Aside from its production, its application field is also increasing, with use not only in commodity applications but also as durables and in biomedicine. In the current PLA production scheme, the most expensive part is not the polymerization itself but obtaining the building blocks lactic acid (LA) and lactide, the actual cyclic monomer for polymerization. Although the synthesis of LA and the polymerization have been studied systematically, reports of lactide synthesis are scarce. Most lactide synthesis methods are described in patent literature, and current energy-intensive, aselective industrial processes are based on archaic scientific literature. This Review, therefore, highlights new methods with a technical comparison and description of the different approaches. Water-removal methodologies are compared, as this is a crucial factor in PLA production. Apart from the synthesis of lactide, this Review also emphasizes the use of chemically produced racemic lactic acid (esters) as a starting point in the PLA production scheme. Stereochemically tailored PLA can be produced according to such a strategy, giving access to various polymer properties. PMID:27071863

  18. Preparation and Characterization of Poly(lactic acid)/ difatty Acyl urea/ modified Clay Nano composite

    International Nuclear Information System (INIS)

    One of the commercially available biodegradable polymer is Poly(lactic acid) (PLA). It is from the family of aliphatic polyesters, which are produced from many renewable resources such as corn and sugar beets. PLA and other biodegradable polymers are readily biodegradable by enzyme action, which have attracted a lot of attention in the scientific community due to a rapid growth of intensive interest in the global environment for alternatives to petroleum-based polymeric materials. Although PLA has good mechanical properties and process ability, its applications are limited due to its brittleness and non flexibility. However, PLA may be used as a biodegradable and renewable plastic for the textile industries, automotive and clinical uses as well as food packaging materials. Since soft and flexible PLA are required to reach end user demands. (author)

  19. Heat capacity of poly(lactic acid)

    International Nuclear Information System (INIS)

    The heat capacity of poly(lactic acid) (PLA) is reported from T=(5 to 600) K as obtained by differential scanning calorimetry (d.s.c.) and adiabatic calorimetry. The heat capacity of solid PLA is linked to its group vibrational spectrum and the skeletal vibrations, the latter being described by a Tarasov equation with Θ1=574 K, Θ2=Θ3=52 K, and nine skeletal vibrations. The calculated and experimental heat capacities agree to ±3% between T=(5 and 300) K. The experimental heat capacity of liquid PLA can be expressed by Cp(liquid)=(120.17+0.076T) J · K-1 · mol-1 and has been compared to the ATHAS Data Bank, using contributions of other polymers with the same constituent groups. The glass transition temperature of amorphous PLA occurs at T=332.5 K with a change in heat capacity of 43.8 J · K-1 · mol-1. Depending on thermal history, semi-crystalline PLA has a melting endotherm between T=(418 and 432) K with variable heats of fusion. For 100% crystalline PLA, the heat of fusion is estimated to be (6.55 ± 0.02) kJ · mol-1 at T=480 K. With these results, the enthalpy, entropy, and Gibbs function of crystalline and amorphous PLA were obtained. For semi-crystalline samples, one can check changes of crystallinity with temperature and judge the presence of rigid-amorphous fractions

  20. Mechanical Properties and Water Absorption Behaviour of Durian Rind Cellulose Reinforced Poly(lactic acid Biocomposites

    Directory of Open Access Journals (Sweden)

    Patpen Penjumras

    2015-01-01

    Full Text Available Environmental concerns have resulted in replacing petrochemically derived polymer with biodegradable renewable resource. In this study, mechanical properties and water absorption behaviour of durian rind cellulose reinforced poly(lactic acid biocomposites were investigated. Poly(lactic acid was mixed with 25 and 35 wt. % of durian rind cellulose that was derived from durian consumption wastes. The biocomposties were melt-blended at 165 and 175 °C with 15 min using a Brabender internal mixer followed by a hot compression moulding technique. The results showed that impact strength and modulus of Young increased with increasing of cellulose content but decreased at higher mixing temperature. Water absorption behaviour of biocomposites as function of days was also investigated. It was found that the water absorption amount of biocomposites increased with increasing of cellulose content and exposure time.    

  1. Synthesis and Characterization of Cross-linked Poly (β-Cyclodextin) Graft Poly(lactic acid) through Direct Polycondensation

    Institute of Scientific and Technical Information of China (English)

    Z.L.Ren; D.D.Lu; Z.Q.Lei

    2007-01-01

    1 Results Polylactide or polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA) have been utilized as bioabsorbable materials in the medical and pharmaceutical fields due to their biodegradable and biocompatible properties[1].However,due to its hydrophobicity and free carboxylic group,PLA or PLGA was not suitable for use to encapsulate the protein.Recently,poly (ε-caprolactone) and poly (D,L-lactide) were respectively grafted onto hydrophilic dextrin and gelatin to obtain the amphiphilic biodeg...

  2. Polylactic Acid Maybe Hope for Solving White Pollution

    Institute of Scientific and Technical Information of China (English)

    Xu Dan

    2007-01-01

    @@ As the pollution problem has aroused more and more attention, greater efforts have been made in developing degradable biological materials without environmental pollution to replace oil-based traditional plastics being used in great quantities today. Among numerous kinds of degradable polymers, polylactic acid has become the 'green' environmental friendly material with the brightest development prospect.

  3. Effects of Biomass in Polyethylene or Polylactic Acid Composites

    Science.gov (United States)

    Previous studies have shown that compounding Polyethylene (PE) or Polylactic acid (PLA) with a dairy-based bioplastic resulted in composites with good mechanical properties. In this study, mass ratios of a dairy-protein-based material (DBP) ranging from 0, 5, 10 and 20 wt% replaced equivalent masse...

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

    Science.gov (United States)

    AbstractThe 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...

  5. The research situation and consumption market analysis of Polylactic acid%聚乳酸研究现状及消费市场分析

    Institute of Scientific and Technical Information of China (English)

    李宪进; 张伟

    2014-01-01

    Polylactic acid is a polymer by polymerization of lactic acid as the main raw materials.Polylactic acid is an ideal green polymer materials,its raw materials are abundant and renewable;no pollution in the produc-tion process,the product is biodegradable.The research status of polylactic acid at home and abroad was mainly in-troduced,the market consumption scale,distribution and development prospect of polylactic acid industry was ana-lyzed.With the people environmental protection consciousness increasing gradually,polylactic acid as biodegrada-ble materials in various fields will be more and more widely.%聚乳酸是以乳酸为主要原料经聚合而成的聚合物,乳酸等原料来源充分且可再生,生产过程无污染,产品可生物降解,是一种理想的绿色高分子材料。主要介绍了聚乳酸国内外研究现状,分析了聚乳酸工业的市场规模、消费分布和发展前景。认为随着人们环保意识逐渐增加,聚乳酸作为生物可降解材料在各领域的应用将越来越广泛。

  6. Technological and economic potential of poly(lactic acid) and lactic acid derivatives

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. New Biodegradable Thermoplastic Multiblock Copolymers from Lactic Acid, ε-Caprolactone, Poly(Ethylene Oxide) and Toluene Diisocyanate

    Institute of Scientific and Technical Information of China (English)

    Jen(o) Borda; Sándor Kéki; Ildikó Bodnár; Nóra Németh; Miklós Zsuga

    2005-01-01

    @@ 1Introduction The interest in finding new biodegradable materials for applications in important areas has been motivated by environmental protection aspects. Foremost among the potentially biodegradable and biocompatible polymers, poly(lactic acid) and poly(ε-caprolactone) received considerable attention as their potential application in a wide range of biomedical and pharmaceutical areas was recognized.

  8. Polylactic acid (PLA) synthesis and modifications: a review

    Institute of Scientific and Technical Information of China (English)

    Yanling CHENG; Shaobo DENG; Paul CHEN; Roger RUAN

    2009-01-01

    This article reviews various methods of synthesizing polycondensation and ring-opening polymerization and modifying properties of polylactic acid (PLA), which may be used as biomaterials, such as a drug carrier in a drug delivery system, as a cell scaffold and suture in tissue engineering, and as packaging materials in packaging engineering field. Copolymerization of lactide with other monomers or polymers such as malic acid, polyethylene glycol (PEG), polyglycolic acid (PGA), or dextran, as well as blending polylactide with natural derivatives and other methods of modification are discussed. Surface modifications of PLA-type copolymers, such as surface coating,chemical modification, and plasma treatment are described.

  9. Biodegradable Tri-Block Copolymer Poly(lactic acid)-poly(ethylene glycol)-poly(L-lysine)(PLA-PEG-PLL) as a Non-Viral Vector to Enhance Gene Transfection

    OpenAIRE

    Na Zhang; Chunhua Fu; Xiaoli Sun; Donghua Liu; Zaijun Lu; Zhijing Chen

    2011-01-01

    Low cytotoxicity and high gene transfection efficiency are critical issues in designing current non-viral gene delivery vectors. The purpose of the present work was to synthesize the novel biodegradable poly (lactic acid)-poly(ethylene glycol)-poly(L-lysine) (PLA-PEG-PLL) copolymer, and explore its applicability and feasibility as a non-viral vector for gene transport. PLA-PEG-PLL was obtained by the ring-opening polymerization of Lys(Z)-NCA onto amine-terminated NH2-PEG-PLA, then acidolysis ...

  10. Longitudinal acoustic properties of poly(lactic acid) and poly(lactic-co-glycolic acid)

    International Nuclear Information System (INIS)

    Acoustics offers rich possibilities for characterizing and monitoring the biopolymer structures being employed in the field of biomedical engineering. Here we explore the rudimentary acoustic properties of two common biodegradable polymers: poly(lactic acid) and poly(lactic-co-glycolic acid). A pulse-echo technique is developed to reveal the bulk speed of sound, acoustic impedance and acoustic attenuation of small samples of the polymer across a pertinent temperature range of 0-70 0C. The glass transition appears markedly as both a discontinuity in the first derivative of the speed of sound and a sharp increase in the acoustic attenuation. We further extend our analysis to consider the role of ethanol, whose presence is observed to dramatically modify the acoustic properties and reduce the glass transition temperature of the polymers. Our results highlight the sensitivity of acoustic properties to a range of bulk properties, including visco-elasticity, molecular weight, co-polymer ratio, crystallinity and the presence of plasticizers.

  11. Influence of lignin on morphology, structure and thermal behavior of polylactic acid-based biocomposites

    Science.gov (United States)

    Canetti, Maurizio; Cacciamani, Adriana; Bertini, Fabio

    2016-05-01

    Polylactic acid (PLA) is a thermoplastic biodegradable polymer that can be made from annually renewable resources. Lignin is a natural amorphous polyphenolic macromolecule inexpensive and easily available. In the present study PLA and acetylated lignin biocomposites were prepared by casting from chloroform solution. PLA can crystallize from the melt in the α and α' forms, depending on the adopted crystallization conditions. The presence of the lignin in the biocomposites can interfere with the crystal formation process. Isothermal crystallizations were performed at different temperatures, the presence of lignin causes an increase of the time of crystallization, while the overall crystallization rate and the spherulite radial growth rate decrease with enhancing the lignin content in the biocomposites.

  12. Holographic gratings recorded in poly(lactic acid)/azo-dye films

    Science.gov (United States)

    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.

  13. Stereocomplex formation of poly-lactic acid and its functional modification by radiation cross-linking

    International Nuclear Information System (INIS)

    Poly-lactic acid (PLA), a biodegradable polyester derived from renewable resources, is attracting the attention as environmentally-friendly polymers. PLA homopolymers consisting of poly-L-lactide (PLLA) and poly-D-lactide (PDLA) has poor heat stability, while the PLA stereocomplex, prepared from different PDLA and a high molecular weight PLLA, reveals a very high melting temperature and enhanced tensile properties. The heat stability can be significantly improved by radiation-induced cross-linking in the presence of triallyl isocyanurate (TAIC). Furthermore, 3% TAIC was suitable ratio for cross-linking of PLA homopolymers by gamma and electron beam irradiation with 30 kGy being an optimum dose for introducing the stable cross-linking network into PLA stereocomplexes. They reveal high heat stability, improved tensile strength and Young's modulus. (S. Ohno)

  14. Improvement Of Mechanical Properties Of Poly(Lactic Acid) By Elastomer

    International Nuclear Information System (INIS)

    Poly(lactic acid), PLA is a biodegradable thermoplastic that has a limited application due to its brittleness. This study has tried to overcome this weakness by blending polybutadiene (BR) into PLA. In the beginning period of the investigation, the preparation of PLA film with the thickness of less than 0.2 mm was prepared using the solvent casting method. The BR contents of 3, 5, 10 and 20 wt % were investigated. Vibracell sonicator was applied to disperse and lessen the rubber particle size in the PLA matrix. It was found that the elongation at break of the samples improved from 11 % for neat PLA to 39 % by blending with 10 wt% BR. However, tensile strength decreased as the BR contents was increased. SEM imaging revealed that the rubber has played an important role in the increase of sample toughness. (author)

  15. Mechanical and Electrical Characteristics of Poly-Lactic Acid which Added Plasticizer

    Science.gov (United States)

    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.

  16. Continuous microcellular foaming of polylactic acid/natural fiber composites

    Science.gov (United States)

    Diaz-Acosta, Carlos A.

    Poly(lactic acid) (PLA), a biodegradable thermoplastic derived from renewable resources, stands out as a substitute to petroleum-based plastics. In spite of its excellent properties, commercial applications are limited because PLA is more expensive and more brittle than traditional petroleum-based resins. PLA can be blended with cellulosic fibers to reduce material cost. However, the lowered cost comes at the expense of flexibility and impact strength, which can be enhanced through the production of microcellular structures in the composite. Microcellular foaming uses inert gases (e.g., carbon dioxide) as physical blowing agents to make cellular structures with bubble sizes of less than 10 microm and cell-population densities (number of bubbles per unit volume) greater than 109 cells/cm³. These unique characteristics result in a significant increase in toughness and elongation at break (ductility) compared with unfoamed parts because the presence of small bubbles can blunt the crack-tips increasing the energy needed to propagate the crack. Microcellular foams have been produced through a two step batch process. First, large amounts of gas are dissolved in the solid plastic under high pressure (sorption process) to form a single-phase solution. Second, a thermodynamic instability (sudden drop in solubility) triggers cell nucleation and growth as the gas diffuses out of the plastic. Batch production of microcellular PLA has addressed some of the drawbacks of PLA. Unfortunately, the batch foaming process is not likely to be implemented in the industrial production of foams because it is not cost-effective. This study investigated the continuous microcellular foaming process of PLA and PLA/wood-fiber composites. The effects of the processing temperature and material compositions on the melt viscosity, pressure drop rate, and cell-population density were examined in order to understand the nucleation mechanisms in neat and filled PLA foams. The results indicated that

  17. Biodegradable Tri-Block Copolymer Poly(lactic acid-poly(ethylene glycol-poly(L-lysine(PLA-PEG-PLL as a Non-Viral Vector to Enhance Gene Transfection

    Directory of Open Access Journals (Sweden)

    Na Zhang

    2011-02-01

    Full Text Available Low cytotoxicity and high gene transfection efficiency are critical issues in designing current non-viral gene delivery vectors. The purpose of the present work was to synthesize the novel biodegradable poly (lactic acid-poly(ethylene glycol-poly(L-lysine (PLA-PEG-PLL copolymer, and explore its applicability and feasibility as a non-viral vector for gene transport. PLA-PEG-PLL was obtained by the ring-opening polymerization of Lys(Z-NCA onto amine-terminated NH2-PEG-PLA, then acidolysis to remove benzyloxycarbonyl. The tri-block copolymer PLA-PEG-PLL combined the characters of cationic polymer PLL, PLA and PEG: the self-assembled nanoparticles (NPs possessed a PEG loop structure to increase the stability, hydrophobic PLA segments as the core, and the primary ε-amine groups of lysine in PLL to electrostatically interact with negatively charged phosphate groups of DNA to deposit with the PLA core. The physicochemical properties (morphology, particle size and surface charge and the biological properties (protection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in HeLa and HepG2 cells of the gene-loaded PLA-PEG-PLL nanoparticles (PLA-PEG-PLL NPs were evaluated, respectively. Agarose gel electrophoresis assay confirmed that the PLA-PEG-PLL NPs could condense DNA thoroughly and protect DNA from nuclease degradation. Initial experiments showed that PLA-PEG-PLL NPs/DNA complexes exhibited almost no toxicity and higher gene expression (up to 21.64% in HepG2 cells and 31.63% in HeLa cells than PEI/DNA complexes (14.01% and 24.22%. These results revealed that the biodegradable tri-block copolymer PLA-PEG-PLL might be a very attractive candidate as a non-viral vector and might alleviate the drawbacks of the conventional cationic vectors/DNA complexes for gene delivery in vivo.

  18. Solvent-free preparation of polylactic acid fibers by melt electrospinning using umbrella-like spray head and alleviation of problematic thermal degradation

    OpenAIRE

    Liu Yong; Zhao Fengwen; Zhang Chi; Zhang Jianming; Yang Weimin

    2012-01-01

    Melt electrospinning is an even simpler and safer method compared with the solution electrospinning in the production of ultra-fine fibers. Polylactic acid (PLA) is a biodegradable and resorbable aliphatic ester that has received significant attention in recent years. PLA is easily degradable at high temperature in the process of melt electrospinning. High efficient fibers were made using our designed umbrella-like spray head spinning facility in this work. To find how to alleviate the ...

  19. Blending of Polyhydroxybutyrate-co-valerate with Polylactic Acid for Packaging Applications – Reflections on Miscibility and Effects on the Mechanical and Barrier Properties

    OpenAIRE

    Jost, V.; Kopitzky, R.

    2015-01-01

    Biopolymers for packaging applications offer many advantages and are therefore of increasing interest. In order to develop a sustainable alternative for petrochemical-based polymers the biobased and biodegradable polymers, the focus of this work are polyhydroxybutyrate-co-valerate (PHBV) and polylactic acid (PLA) (and copolymers). Blending of these two biopolymers was reviewed under thermodynamic aspects and backed with own results. Additionally, different ways of improving the miscibility we...

  20. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

    OpenAIRE

    Marwah Rayung; Nor Azowa Ibrahim; Norhazlin Zainuddin; Wan Zuhainis Saad; Nur Inani Abdul Razak; Buong Woei Chieng

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of th...

  1. Polylactic Acid Nanoparticles Targeted to Brain Microvascular Endothelial Cells

    Institute of Scientific and Technical Information of China (English)

    WANG Huafang; HU Yu; SUN Wangqiang; XIE Changsheng

    2005-01-01

    In this work, blank polylactic acid (PLA) nanoparticles with unstained surface were prepared by the nano-deposition method. On the basis of the preparation, the effect of surface modification on brain microvascular endothelial cells (BMECs) targeting was examined by in vivo experiments and fluorescence microscopy. The results showed that PLA nanoparticles are less toxic than PACA nanoparticles but their BMECs targeting is similar to PACA nanoparticles. The experiments suggest that drugs can be loaded onto the particles and become more stable through adsorption on the surface of PLA nanoparticles with high surface activity. The surface of PLA nanoparticles was obviously modified and the hydrophilicity was increased as well in the presence of non-ionic surfactants on PLA nanoparticles. As a targeting moiety, polysobate 80 (T-80) can facilitate BMECs targeting of PLA nanoparticles.

  2. Thermogravimetric and DSC testing of poly(lactic acid) nanocomposites

    International Nuclear Information System (INIS)

    Highlights: • The presence of nanoadditivities in PLA matrix improves thermal stability of PLA. • Shielding effect main reason for PLA thermal stability by nanofillers. • Thermal degradation suppression in UV-irradiated PLA by the removing of unstable compounds. - Abstract: Polymer nanocomposites based on poly(lactic acid), PLA, and two types of nanofillers: nanosilver and nanoclay were obtained by casting method. The thermal properties of PLA and nanocomposites have been studied by thermogravimetric analysis (TA) and differential scanning calorimetry (DSC). All samples have been UV-irradiated and the effect of photoprocess on their thermal stability has been estimated. It was found that nanoadditives and UV irradiation causes an increase of the activation energy of PLA thermal decomposition. DSC result supplies information on glass transition and crystallization/melting processes in PLA in the presence of nanosilver or nanoclay, also after exposure to UV

  3. Compostability assessment of nano-reinforced poly(lactic acid) films.

    Science.gov (United States)

    Balaguer, M P; Aliaga, C; Fito, C; Hortal, M

    2016-02-01

    Nanomaterials can provide plastics with great advantages on mechanical and active properties (i.e. release and capture of specific substances). Therefore, packaging is expected to become one of the leading applications for these substances by 2020. There are some applications already in the market. Nevertheless, there is still some areas under development. A key issue to be analyzed is the end-of-life of these materials once they become waste, and specifically when nanomaterials are used in biodegradable products. The present study evaluated the disintegration, biodegradability, and ecotoxicity of poly(lactic acid) films reinforced with the three following nanomaterials: (1) montmorillonite modified with an ammonium quaternary salt, (2) calcium carbonate and (3) silicon dioxide. Results on disintegration showed that films completely disintegrated into visually indistinguishable residues after 6-7weeks of incubation in composting environment. Moreover, no differences were observed in the evolution of the bioresidue with respect to color, aspect, and odor in comparison with the control. It was also observed that nanomaterials did not significantly reduce the level of biodegradability of PLA (p>0.05). In fact, biodegradation was higher, without finding significant differences (p>0.05), in all the nano-reinforced samples with respect to PLA after 130days in composting (9.4% in PLA+Nano-SiO2; 34.0% in PLA+Clay1; 48.0% in PLA+Nano-CaCO3). Finally, no significant differences (p>0.05) in ecotoxicity in plants were observed as a result of the incorporation of nanoparticles in the PLA matrix. PMID:26589869

  4. Application of Lemongrass Oil-Containing Polylactic Acid Films to the Packaging of Pork Sausages

    Science.gov (United States)

    2016-01-01

    Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging. PMID:27433114

  5. Thermal characterization of polyhydroxyalkanoates and poly(lactic acid) blends obtained by injection molding

    OpenAIRE

    Loureiro, Nuno Calçada; Ghosh, Satyabrata; Viana, J. C.; Esteves, José Luis

    2015-01-01

    In this work we present the thermal characterization of the full scope of polyhydroxyalcanoate and poly(lactic acid) blends obtain by injection molding. Blends of polyhydroxyalcanoate and poly(lactic acid) (PHA/PLA) were prepared in different compositions ranging from 0–100% in steps of 10%. The blends were injection molded and then characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The increment of PHA fractio...

  6. 聚乳酸的合成方法%Synthesis of polylactic acid

    Institute of Scientific and Technical Information of China (English)

    梁博

    2008-01-01

    聚乳酸是一类具有优良生物相容性和可生物降解的高分子材料,被广泛应用于医用领域,受到越来越多的关注.聚乳酸的合成主要有两种方法: 丙交酯的开环聚合和乳酸直接缩聚.综述近年来聚乳酸合成研究的最新进展,介绍了聚乳酸聚合的两种高效方法-反应挤出法和直接-固相聚合法,并展望了聚乳酸合成研究的前景.%Polylactic acid (PLA) is a biocompatible and biodegradable polymer, thus it is widely used in the medical area and is much more attractive. There are two main methods to synthetizing PLA, ring-opening polymerization of lactide and condensation polymerization of lactic acid. In this paper, the process of the new research of the PLA synthesis was reviewed. Beside, the PLA synthesis methods of reactive extrusion and direct melting polycondensation were introduced, which are two high efficiency methods. Finally, the foreground of PLA synthesis was prospected.

  7. Characterization of Polylactic Acid/ Microcrystalline Cellulose/ Montmorillonite Hybrid Composites

    International Nuclear Information System (INIS)

    The objective of this study is to investigate the effect of montmorillonite (MMT)/ microcrystalline cellulose (MCC) hybrid fillers on mechanical properties and morphological characteristics of polylactic acid (PLA) composites. PLA/ MMT nano composites and PLA/ MMT/ MCC hybrid composites were prepared by solution casting method. Morphology and tensile properties of PLA composites were investigated using Field emission scanning electron microscopy and Instron tensile testing machine. The maximum tensile strength of PLA/ MMT nano composites was obtained with 5 phr contents of MMT, which corresponding to 30.75 MPa. Based on optimized formulation of PLA/ MMT nano composites (5 phr MMT contents), various amounts of MCC (0 to 7 phr) were added into optimum formulation of PLA/ MMT in order to produce PLA/ MMT/ MCC hybrid composites. Fourier transform infrared spectroscopy revealed some level of interaction between PLA and both MMT and MCC in the hybrid composites. However, the percent elongation at break of the hybrid composites was generally higher than PLA/ MMT nano composites. Additionally, Young's modulus of the PLA/ MMT/ MCC hybrid composites increased gradually with increasing of MCC contents and was higher than PLA/ MMT at all compositions. The present results are the first among a series of experiments that have been designed in order to probe the effect of MMT and MCC in the PLA. (author)

  8. Evaluation of polylactic acid nanoparticles safety using Drosophila model.

    Science.gov (United States)

    Legaz, Sophie; Exposito, Jean-Yves; Lethias, Claire; Viginier, Barbara; Terzian, Christophe; Verrier, Bernard

    2016-10-01

    Cytotoxicity of nanoparticles and their sub-lethal effect on cell behavior and cell fate are a high topic of studies in the nanomaterial field. With an explosion of nanoparticle types (size, shape, polarity, stiffness, composition, etc.), Drosophila has become an attractive animal model for high throughput analysis of these nanocarriers in the drug delivery field with applications in cancer therapy, or simply to generate a fast and complete cytotoxic study of a peculiar nanoparticle. In respect to that, we have conducted an in cellulo study of poly(lactic acid) (PLA) nanoparticle cytotoxicity, and determined that near lethal nanoparticle doses, oxidative stress as well as P53 and ATP pathways may lead to cell cycle arrest at G1, and ultimately to cell death. Neither viability nor the development of Drosophila larvae are affected by the ingestion of PLA nanoparticles at sub-lethal concentrations. Drosophila will be a useful model to study PLA and PLA-modified nanoparticle toxicity, and nanoparticle fate after ingestion. PMID:27108761

  9. Fracture behavior of quenched poly(lactic acid

    Directory of Open Access Journals (Sweden)

    2011-01-01

    Full Text Available The effect of a quenching treatment applied on heated cast sheet extruded films of two poly(lactic acid (PLA commercial grades, with different optical purities, was studied. The thermal and mechanical properties of the films, as well as their fracture behavior, were assessed by differential scanning calorimetry (DSC, tensile tests, and the essential work of fracture (EWF approach. The heating-quenching treatment causes a de-aging effect with an increase in the free volume of polymer chains evidenced by a decrease in the glass transition temperature (Tg and a decrease in the tensile stiffness and yield stress. As a result, there is an abrupt increase in ductility, finding a dramatic change in the fracture behavior, from brittle to ductile. The use of digital image correlation (DIC of the strain field analysis during fracture testing has allowed relating the decrease on the yield stress promoted by quenching with the crack propagation kinetics. The use of the EWF method to characterize the fracture toughness of PLA has allowed to measure this enhancement on toughness, finding that the specific essential work of fracture (we and the plastic term (βwp parameters increased 120% and 1200%, respectively, after the quenching process.

  10. New Polylactic Acid Composites Reinforced with Artichoke Fibers

    Directory of Open Access Journals (Sweden)

    Luigi Botta

    2015-11-01

    Full Text Available In this work, artichoke fibers were used for the first time to prepare poly(lactic acid (PLA-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w were prepared by the film-stacking method: the first one (UNID reinforced with unidirectional long artichoke fibers, the second one (RANDOM reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM. Moreover, a theoretical model, i.e., Hill’s method, was used to fit the experimental Young’s modulus of the biocomposites. The quasi-static tensile tests revealed that the modulus of UNID composites is significantly higher than that of the neat PLA (i.e., ~40%. Moreover, the tensile strength is slightly higher than that of the neat matrix. The other way around, the stiffness of RANDOM composites is not significantly improved, and the tensile strength decreases in comparison to the neat PLA.

  11. CHARACTERIZATION OF POLYLACTIC ACID COLLOIDS FOR IN SITU BIOREMEDIATION

    Energy Technology Data Exchange (ETDEWEB)

    Ashley N. Westbrook

    2003-07-01

    Groundwater contamination is a widespread problem. As human activities generate chemical wastes, we seek quick, yet not always environmentally friendly, ways to dispose of them. Often, chemicals are dumped into waste containers and buried. Unfortunately, these chemicals may spill or leak, seep deeper into the ground, and eventually reach groundwater. Chlorinated organic solvents such as trichloroethene, tetrachloroethane, and chloroform are common contaminants in groundwater [1]. These solvents originate from chemical spills, tank leaks, and waste disposal practices [2]. Such contaminants are harmful to humans, and need to be removed to restore clean groundwater. There are two types of methods to clean chemically contaminated soil and groundwater: ex situ and in situ. Both types have advantages and disadvantages. In situ remediation avoids the cost of removing the contaminated material and has a lower risk of worker exposure to the contaminants. One in situ technique that shows promise is remediation, which uses microorganisms to anaerobically degrade contaminants. In bioremediation in situ, the microorganisms that are already present in the ground utilize nutrients that are injected into the ground to metabolize the contaminants into nonhazardous materials. The nutrients serve as a carbon source for the microbes. Though this method has been used with some success, there have been problems with too rapid release of nutrients to the microbes. In these cases, the microbes multiplied too rapidly and caused biofouling. This can occur when the nutrient content of the bioremediation solution is too high, as when lactate or lactic acid is the nutrient. Lactic acid is typically produced in carbohydrate matter by fermentation, and is used mainly in the food and pharmaceutical industries [3]. Because it has been found difficult to uniformly distribute lactate solutions in a contaminated area due to biofouling, it was suggested that polylactic acid, in colloidal form, be used

  12. 聚乳酸微球的制备%Preparation of polylactic acid microspheres

    Institute of Scientific and Technical Information of China (English)

    孟立山; 姚新建

    2011-01-01

    Using L-lactic acid as raw materials and tin as a catalyst, and through the activity of lactide ring-opening polymerization, the controlled molecular weight polylactic acid was synthesized. FTIR results showed that controlled molecular weight polylactic acid was synthesized. Using dichloromethane as solvent, polyvinyl alcohol as surfactant, polylactic acid microspheres were prepared. Effect of PVA concentration on the polylactic acid microspheres was researched. Results showed that when the PVA concentration increased,the microspheres became smaller, but the particle size distribution decreased. Concentration of PVA was 1 % , polylactic acid into the ball was better.%以L-乳酸为原料,锡粒为催化剂,实现了丙交酯的开环聚合反应,红外光谱结果表明,合成了分子量可控的聚乳酸.以二氯甲烷为溶剂,聚乙烯醇为表面活性剂,制备了聚乳酸微球,研究了聚乙烯醇浓度对聚乳酸微球的影响.结果表明,当聚乙烯醇浓度增加时,微球半径变小,但粒径分布均匀度下降,聚乙烯醇浓度为1%时,聚乳酸成球效果较好.

  13. 聚乳酸载药系统的研究进展%The Research Progress of Polylactic Acid Containing Drug Delivery System

    Institute of Scientific and Technical Information of China (English)

    林丽丽

    2012-01-01

    Polylactic acid and its copolymers,due to its biocompatibility and biodegradability,were widely used in medicine and biology.The paper summarized the study of new drug-loaded polylactide and its copolymers at home and abroad.Polylactic acid to illustrate the advantages as a drug carrier and development prospects.%聚乳酸及其共聚物由于其生物相容性和生物可降解性,被广泛应用于医药和生物学领域。文章就国内外对聚乳酸及其共聚物作为新型载药系统的研究,进行了归纳总结。旨在说明聚乳酸作为药物载体的优势和发展前景。

  14. Magnetite-polylactic acid nanoparticles by surface initiated organocatalysis ring opening polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Alexandrina [National Institute of R and D for Isotopic and Molecular Technologies (Romania); Leistner, Joachim [Humboldt-University Berlin, Institute of Chemistry (Germany); Turcu, Rodica, E-mail: rodica.turcu@itim-cj.ro [National Institute of R and D for Isotopic and Molecular Technologies (Romania)

    2013-08-15

    Organocatalysis by 4-N,N-dimethylaminopyridine was employed for ring opening polymerization of lactide initiated at magnetic nanoparticles covered by glycerol phosphate or ascorbic acid phosphate. The resulting magnetite-polylactic acid nanoparticles exhibit high colloidal stability in water and alcohol. Their morphology was investigated by transmission electron microscopy and the chemical structure was elucidated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The increase in mass after coating the nanoparticles was determined by thermogravimetric analysis, while dynamic light scattering revealed the increase in hydrodynamic size. Magnetic measurements revealed superparamagnetic behavior and high magnetization values. The magnetite-polylactic acid nanoparticles were further used for magnetic tagging of biotin.

  15. Practical preparation procedures for docetaxel-loaded nanoparticles using polylactic acid-co-glycolic acid

    Directory of Open Access Journals (Sweden)

    Keum CG

    2011-10-01

    Full Text Available Chang-Gu Keum1*, Young-Wook Noh1*, Jong-Suep Baek1, Ji-Ho Lim1, Chan-Ju Hwang1, Young-Guk Na1, Sang-Chul Shin2, Cheong-Weon Cho11College of Pharmacy and Institute of Drug Research and Development, Chungnam National University, Gungdong, Yuseonggu, Daejeon, South Korea; 2College of Pharmacy, Chonnam National University, Yongbongdong, Buggu, Gwangju, South Korea *These authors contributed equally to this work Background: Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA, are the most intensively investigated polymers for drug delivery systems. The objective of this study was to explore fully the development of a PLGA nanoparticle drug delivery system for alternative preparation of a commercial formulation. In our nanoparticle fabrication, our purpose was to compare various preparation parameters. Methods: Docetaxel-loaded PLGA nanoparticles were prepared by a single emulsion technique and solvent evaporation. The nanoparticles were characterized by various techniques, including scanning electron microscopy for surface morphology, dynamic light scattering for size and zeta potential, x-ray photoelectron spectroscopy for surface chemistry, and high-performance liquid chromatography for in vitro drug release kinetics. To obtain a smaller particle, 0.2% polyvinyl alcohol, 0.03% D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS, 2% Poloxamer 188, a five-minute sonication time, 130 W sonication power, evaporation with magnetic stirring, and centrifugation at 8000 rpm were selected. To increase encapsulation efficiency in the nanoparticles, certain factors were varied, ie, 2–5 minutes of sonication time, 70–130 W sonication power, and 5–25 mg drug loading. Results: A five-minute sonication time, 130 W sonication power, and a 10 mg drug loading amount were selected. Under these conditions, the nanoparticles reached over 90% encapsulation efficiency. Release kinetics showed that 20

  16. Biocomposites based on poly(lactic acid/willow-fiber and their injection moulded microcellular foams

    Directory of Open Access Journals (Sweden)

    M. T. Zafar

    2016-02-01

    Full Text Available Natural fiber reinforced biocomposites have recently attracted many researchers because of their biodegradability, cost effectiveness and ecofriendliness. The present study investigates the properties of willow-fiber reinforced poly(lactic acid based composites and their foam processability. Microcellular foams of the composites were prepared by foam injection moulding using nitrogen gas as the blowing agent. The effects of willow-fiber addition on the morphology, mechanical properties, thermal stability, crystallization, and heat deflection temperature (HDT were studied. At 30 weight percent [wt%] willow-fiber content, unfoamed composites showed good improvement in specific tensile and flexural moduli. Addition of willow-fiber increased crystallinity and the rate of crystallization and yielded narrow crystallite size distribution as observed by differential scanning calorimetry (DSC. Scanning electron microscopy (SEM results of the foamed composites revealed that increase in willow-fiber content caused smaller average cell size and higher cell density. Specific notch impact strength of foamed composites at both 20 and 30 wt% willow-fiber content showed increasing trend compared to that of their unfoamed counterparts.

  17. Poly-lactic acid and agarose gelatin play an active role in the recovery of spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective To investigate the role of poly-lactic acid and agarose gelatin in promoting the functional recovery of the injured spinal cord. Methods Poly-lactic acid (PLA) or agarose was embedded in the space between two stumps of the hemisectioned spinal cord. Immunohistochemistry was used to show astroglia proliferation and the infiltration of RhoA-positive cells. Locomotor activity recovery was evaluated by testing the function of hindlimbs. Results Astroglias and RhoA labeled non-neuronal cells accumulated in the area adjacent to the implant, while the number of RhoA-positive cells was decreased dramatically in the absence of implant. Animals implanted with agarose gelatin recovered more quickly than those with PLA, concomitant with a higher survival rate of the neurons. Conclusion Both PLA and agarose gelatin benefited the recovery of spinal cord after injury by providing a scaffold for astroglia processes. Modulation of the rigidity, pore size and inner structure of PLA and agarose gelatin might make these biodegradable materials more effective in the regeneration of the central nervous system (CNS).

  18. Sandwich-Architectured Poly(lactic acid)-Graphene Composite Food Packaging Films.

    Science.gov (United States)

    Goh, Kunli; Heising, Jenneke K; Yuan, Yang; Karahan, Huseyin E; Wei, Li; Zhai, Shengli; Koh, Jia-Xuan; Htin, Nanda M; Zhang, Feimo; Wang, Rong; Fane, Anthony G; Dekker, Matthijs; Dehghani, Fariba; Chen, Yuan

    2016-04-20

    Biodegradable food packaging promises a more sustainable future. Among the many different biopolymers used, poly(lactic acid) (PLA) possesses the good mechanical property and cost-effectiveness necessary of a biodegradable food packaging. However, PLA food packaging suffers from poor water vapor and oxygen barrier properties compared to many petroleum-derived ones. A key challenge is, therefore, to simultaneously enhance both the water vapor and oxygen barrier properties of the PLA food packaging. To address this issue, we design a sandwich-architectured PLA-graphene composite film, which utilizes an impermeable reduced graphene oxide (rGO) as the core barrier and commercial PLA films as the outer protective encapsulation. The synergy between the barrier and the protective encapsulation results in a significant 87.6% reduction in the water vapor permeability. At the same time, the oxygen permeability is reduced by two orders of magnitude when evaluated under both dry and humid conditions. The excellent barrier properties can be attributed to the compact lamellar microstructure and the hydrophobicity of the rGO core barrier. Mechanistic analysis shows that the large rGO lateral dimension and the small interlayer spacing between the rGO sheets have created an extensive and tortuous diffusion pathway, which is up to 1450-times the thickness of the rGO barrier. In addition, the sandwiched architecture has imbued the PLA-rGO composite film with good processability, which increases the manageability of the film and its competency to be tailored. Simulations using the PLA-rGO composite food packaging film for edible oil and potato chips also exhibit at least eight-fold extension in the shelf life of these oxygen and moisture sensitive food products. Overall, these qualities have demonstrated the high potential of a sandwich-architectured PLA-graphene composite film for food packaging applications. PMID:27028268

  19. Obtaining a Flexible Film Elaborated from Cassava Thermoplastic Starch and Polylactic Acid

    Directory of Open Access Journals (Sweden)

    Germán A. Arboleda

    2015-01-01

    Full Text Available A flexible film was obtained from a blend of cassava thermoplastic starch and polylactic acid, using maleic anhydride as coupling agent. For this, an experimental design with three factors was used: polylactic acid content, coupling agent content, and temperature profile of the blown extrusion. It was found that the three factors generated significant differences on the response variables of tensile mechanical properties individually as in their triple interaction. Differential scanning calorimetry (DSC was used by understanding the behavior of thermal properties of TPS/PLA blends with and without coupling agent, finding similar results between both. From this, the combination with 28% polylactic acid, 0.87% coupling agent, and 155.75°C temperature profile permitted the obtaining of a material with outstanding mechanical properties and offered advantages from the economic point of view.

  20. Deposition of LDH on plasma treated polylactic acid to reduce water permeability

    KAUST Repository

    Bugatti, Valeria

    2013-04-01

    A simple and scalable deposition process was developed to prepare polylactic acid (PLA) coatings with enhanced water barrier properties for food packaging applications. This method based on electrostatic interactions between the positively charged layers of layered double hydroxides (LDHs) modified with ionic liquids (ILs) and the negatively charged plasma treated polylactic acid leads to homogeneous, stable, and highly durable coatings. Deposition of the LDH coatings increases the surface hydrophobicity of the neat PLA, which results to a decrease in water permeability by about 35%. © 2013 Elsevier Inc.

  1. Effect of gamma irradiation on physicochemical properties of commercial poly(lactic acid) clamshell for food packaging

    Science.gov (United States)

    Madera-Santana, Tomás J.; Meléndrez, R.; González-García, Gerardo; Quintana-Owen, Patricia; Pillai, Suresh D.

    2016-06-01

    Poly(lactic acid) (PLA) is a well-known biodegradable polymer with strong potential application in food packaging industry. In this paper, samples of PLA clamshell for tomatoes packaging were exposed with 60CO γ-ray's source (1.33 MeV) at different dose levels (0, 10, 60, 150, 300, and 600 kGy), at room temperature and in presence of air. The physicochemical properties of neat PLA and sample exposed to gamma irradiation were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile measurements. Results show as the dose increases, the molecular weight (Mw), melting temperature (Tm), tensile strength and elongation at break decreased. However, the tensile modulus increased with increasing doses. The surface of PLA clamshells was degraded (scratches and minor cracks) when samples were exposed to doses greater than 60 kGy.

  2. INFLUENCE OF THE ATMOSPHERIC PLASMA CONDITIONS PROCESS ON WETTABILITY OF THE BIOPOLYMER PLA (POLYLACTIC ACID FOR TECHNOLOGICAL APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Amparo Jordá Vilaplana

    2013-01-01

    Full Text Available Recently a remarkable growth in the biodegradable polymers applications has been observed in many industrial sectors. This kind of polymers offers a wide variety of properties such a traditional and easy processing conditions, good chemical barrier behaviour, surface finishing versatility, light, etc. What’s more the main property of these polymers is their biodegradability and environmental friendly behaviour. One of the most important commercial biopolymer is polylactic acid or PLA. This is one polyester kind from renewable sources that its produced for anaerobic fermentation of substrates with carbon like glucose, lactose, starch, molasses, etc with microorganisms like lactobacillus bacterium.Despite this, many polymeric materials offer very low surface energy values. So, in order to obtain polymeric joints, surface cover or printing for technological applications, these surfaces are characterized by poor wettability properties. For solving this real problem we can use some surface treatments like chemicals solvents, physical treatment, etc. One of the most interesting treatment is the plasma technology because is an environmental friendly technology and promotes high surface energy values on polymer surface, improves wettability property.In this work we have used atmospheric plasma technology to modify wettability properties of a polylactic acid PLA, with different conditions process to optimize the parameters treatment. On the other hand, we have evaluated the main actuation mechanism of the atmospheric plasma technology on polymeric surface.Wettability changes on PLA surface have been evaluated using contact angle measurements by means of four test liquids with different polarities. Characterization of the surface changes due to the atmospheric plasma fictionalization mechanism has been carried out using infrared spectroscopy (FTIR, X-Ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM and atomic force microscopy (AFM

  3. Antimicrobial activity of nisin incorporated in pectin and polylactic acid composite films against Listeria monocytogenes

    Science.gov (United States)

    Extruded composite films from 20% pectin and 80% polylactic acids (PLA) were developed and nisin was loaded into films by a diffusion post extrusion. Inhibitory activities of the films against Listeria monocytogenes were evaluated in brain heart infusion (BHI) broth, liquid egg white and orange juic...

  4. Preparation of poly(lactic acid) and pectin composite films intended for application in antimicrobial packaging

    Science.gov (United States)

    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...

  5. Deformation and structure evolution of glassy poly(lactic acid) below the glass transition temperature

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Li, Hongfei; Zhang, Yao;

    2015-01-01

    Poly(lactic acid) (PLA) is a bio-based and compostable thermoplastic polyester that has rapidly evolved into a competitive commodity material over the last decade. One key bottleneck in expanding the field of application of PLA is the control of its structure and properties. Therefore, in situ in...

  6. Morphology and thermal degradation study of poly(lactic acid)/synthetic mica composites

    International Nuclear Information System (INIS)

    Poly(lactic acid) (PLA)/synthetic mica composites has been little studied in the literature. In this work, an organophilic synthetic mica was used to prepare PLA nanocomposites. The composites were obtained at an internal mixer containing 3, 5, 7 and 10 wt% of mica. The materials were analyzed by x-ray diffraction, thermogravimetric analysis and gel permeation chromatography. (author)

  7. EVALUATION OF POLY(LACTIC ACID) AND AGRICULTURAL COPRODUCTS AS GREEN COMPOSITE MATERIALS

    Science.gov (United States)

    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 ...

  8. Sugar beet pulp and poly(lactic acid) composites using methylene diphenyl diisocyanate as coupling agent

    Science.gov (United States)

    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...

  9. Solution blow spun Poly(lactic acid)/Hydroxypropyl methylcellulose nanofibers with antimicrobial properties

    Science.gov (United States)

    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...

  10. Preparation and Quality Control of 166Ho Labelled Polylactic Acid Microspheres for radiotherapy

    Czech Academy of Sciences Publication Activity Database

    Kropáček, Martin; Melichar, František; Klejzarová, Michaela; Ventruba, Jiří; Tomeš, Marek; Mirzajevová, Marcela

    2007-01-01

    Roč. 2, č. 332 (2007), s. 34-34. ISSN 1619-7070 R&D Projects: GA AV ČR 1QS100480501 Institutional research pla n: CEZ:AV0Z10480505 Keywords : polylactic acid microspheres * 166Ho * liver tumour therapy Subject RIV: FR - Pharmacology ; Medidal Chemistry

  11. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid/Oil Palm Empty Fruit Bunch Fiber Composites

    Directory of Open Access Journals (Sweden)

    Marwah Rayung

    2014-08-01

    Full Text Available In this work, biodegradable composites from poly(lactic acid (PLA and oil palm empty fruit bunch (OPEFB fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant.

  12. The effect of fiber bleaching treatment on the properties of poly(lactic acid)/oil palm empty fruit bunch fiber composites.

    Science.gov (United States)

    Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

  13. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

    Science.gov (United States)

    Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

  14. A new approach in compatibilization of the poly(lactic acid)/thermoplastic starch (PLA/TPS) blends.

    Science.gov (United States)

    Akrami, Marzieh; Ghasemi, Ismaeil; Azizi, Hamed; Karrabi, Mohammad; Seyedabadi, Mohammad

    2016-06-25

    In this study, a new compatibilizer was synthesized to improve the compatibility of the poly(lactic acid)/thermoplastic starch blends. The compatibilizer was based on maleic anhydride grafted polyethylene glycol grafted starch (mPEG-g-St), and was characterized using Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis (DMTA) and back titration techniques. The results indicated successful accomplishment of the designed reactions and formation of a starch cored structure with many connections to m-PEG chains. To assess the performance of synthesized compatibilizer, several PLA/TPS blends were prepared using an internal mixer. Consequently, their morphology, dynamic-mechanical behavior, crystallization and mechanical properties were studied. The compatibilizer enhanced interfacial adhesion, possibly due to interaction between free end carboxylic acid groups of compatibilizer and active groups of TPS and PLA phases. In addition, biodegradability of the samples was evaluated by various methods consisting of weight loss, FTIR-ATR analysis and morphology. The results revealed no considerable effect of compatibilizer on biodegradability of samples. PMID:27083816

  15. A CRADLE TO GATE LIFE CYCLE ANALYSIS OF THE BIOPOLYMER POLYLACTIC ACID: LOOKING BEYOND GLOBAL WARMING AND FOSSIL FUEL USE

    Science.gov (United States)

    Derived from corn, the biopolymer polylactic acid (PLA) has recently emerged in the marketplace and is advertised as a sustainable alternative to petroleum-based polymers. Research into the environmental implications of biobased production has focused primarily on global warming...

  16. Preparation of etoposide Polylactic Acid Microspheres%依托泊苷聚乳酸微球的制备

    Institute of Scientific and Technical Information of China (English)

    姜素芳; 张云坤; 周学军

    2011-01-01

    目的::用生物可降解材料聚乳酸制备依托泊苷微球,并对其体外释药特性进行研究.方法:采用乳化-溶剂扩散法制备依托泊苷聚乳酸微球,通过正交试验确定最佳处方工艺;采用紫外分光光度法测定微球载药量、包封率和体外药物释放,利用光学显微镜观察微球形态和粒径分布.结果:所得微球外观圆整,平均粒径为12.87 μm,载药量为14.79%,药物包封率为61.09%,体外释药符合Higuchi方程.结论:依托泊苷聚乳酸微球制备工艺稳定,体外释药符合长效制剂特征.%Objective To prepare etoposide microspheres using thg biodegradable meterials-polylactic acid and to study its release characteristics in vitro. Methods The polylactic acid microspheres were prepared by emulsion-solvent diffusion method and the orthogonal test design was used to optimize the formulation and technology .The drug-loading,emcapsulation and release in vitro were determined by ultraviolet spectrophotometry and the appearance and particle size of microspheres was observed by light microscope. Results The shape of etoposide microspheres was spherical with mean particle size of 12.87 ujn.The drug loading and encapsulation efficiency were 14.79% and 61.09%, respectively. The in vitro release characteristics of microspheres was found to agree with Higuchi equation. Conclusion The technology of preparation was successful and etoposide polylactic acid micropheres showed significant sustained release.

  17. Polylactic Acid-Based Polymer Blends for Durable Applications

    Science.gov (United States)

    Finniss, Adam

    There has been considerable scientific interest in both research and commercial communities as of late in the area of biologically based or sourced plastics. As the consumption of petroleum rises and concerns about climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use PLA more widely, especially in durable applications. Unfortunately, PLA has several drawbacks that hinder more widespread usage of the material as a durable item: it has low ductility and impact strength in bulk applications, along with poor stability in the face of heat, humidity or liquid media. To combat these deficiencies, a number of techniques were investigated. Samples were annealed to create crystalline domains that would improve mechanical properties and reduce diffusion, blended with graphene to create barriers to diffusion throughout the material, or compounded with a polycarbonate (PC) polymer phase to protect the PLA phase and to enhance the mechanical properties of the blend. If a material containing biologically sourced components with good mechanical properties can be created, it would be desirable for durable uses such as electronics components or as an automotive grade resin. Crystallization experiments were carried out in a differential scanning calorimeter to determine the effects of heat treatment and additives on the rather slow crystallization kinetics of PLA polymer. It was determined that the blending in of the PC phase did not significantly alter the kinetics or mechanism of crystal growth. The addition of graphene to any PC/PLA formulation served as a nucleating agent which speeded up the crystallization kinetics markedly, in some cases by several orders of magnitude. Results obtained from these experiments were internally consistent

  18. Poly(lactic acid) (PLA) based nanocomposites-a novel way of drug-releasing

    International Nuclear Information System (INIS)

    In this communication, poly(lactic acid) nanofibers have been fabricated by electrospinning and then poly(lactic acid) (PLA) based nanocomposites have been prepared by accumulating anticancer drug daunorubicin on PLA nanofibers combined with TiO2 nanoparticles. Our atomic force microscopy (AFM) and laser-scanning confocal microscope (LSCM) studies demonstrate that the respective drug molecules could be readily self-assembled on the surface of the blends of nano-TiO2 with PLA polymer nanocomposites, which could further efficiently facilitate the drug permeation and accumulation on the target leukemia K562 cells. Besides, the respective new nanocomposites have good biocompatibility, ease of surface chemistry modification and very high surface area, which may afford the possibility for their promising application in pharmacology and biomedical engineering areas. (communication)

  19. Preparation of poly(lactic acid) composite hollow spheres containing calcium carbonates.

    Science.gov (United States)

    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

  20. Enhancement of Mechanical and Thermal Properties of Polylactic Acid/Polycaprolactone Blends by Hydrophilic Nanoclay

    OpenAIRE

    Chern Chiet Eng; Nor Azowa Ibrahim; Norhazlin Zainuddin; Hidayah Ariffin; Wan Md Zin Wan Yunus; Yoon Yee Then; Cher Chean Teh

    2013-01-01

    The effects of hydrophilic nanoclay, Nanomer PGV, on mechanical properties of Polylactic Acid (PLA)/Polycaprolactone (PCL) blends were investigated and compared with hydrophobic clay, Montmorillonite K10. The PLA/PCL/clay composites were prepared by melt intercalation technique and the composites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), Scanning Electron Microscopy (SEM),...

  1. Use of Poly-Lactic Acid (PLA) to Enhance Properties of Paper Based on Recycled Pulp

    OpenAIRE

    Klaus Doelle; Le, Anh T.; Thomas E. Amidon; Biljana M. Bujanovic

    2014-01-01

    Nowadays, recycled paper is broadly used due to environmental reasons. Furthermore, the addition of starch as a dry strength additive improves the properties of recycled paper. Poly-Lactic Acid (PLA), a product from bio-refinery process, has recently been shown to act as a promising strength additive that could be used in combination with starch to further improve the strength of paper. In this study, the use of PLA of three molecular weights (MW) in combination with fo...

  2. Preparation and characterization of interpenetrating networks based on polyacrylates and poly(lactic acid)

    OpenAIRE

    H. Kaczmarek; I. Vukovic-Kwiatkowska

    2012-01-01

    Three different, multifunctional acrylic monomers were photopolymerized in a matrix of poly(lactic acid), PLA, using 2-hydroxy-2-methyl-1-phenyl-propan-1-one as a photoinitiator. The kinetics of the photopolymerization of monomers in PLA, studied with Fourier Transform Infrared Spectroscopy, has been compared to analogous processes of pure monomers under the same conditions (room temperature, air atmosphere). Additionally, poly(ethylene glycol) was added to acrylate/PLA blends as plasticizer....

  3. Barrier Properties of Polylactic Acid in Cellulose Based Packages Using Montmorillonite as Filler

    OpenAIRE

    Daniela Sánchez Aldana; Eduardo Duarte Villa; Miguel De Dios Hernández; Guillermo González Sánchez; Quintín Rascón Cruz; Sergio Flores Gallardo; Hilda Piñon Castillo; Lourdes Ballinas Casarrubias

    2014-01-01

    Polylactic acid (PLA) and montmorillonite (CB) as filler were studied as coatings for cellulose based packages. Amorphous (AM) and semi crystalline (SC) PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was three concentrations and coating was performed by casting. Contact angle (CA), water vapor (WVP) and grease permeabilities were measured for each resultant package and were compared to commercial materials (Glassine Paper, Gre...

  4. Poly(lactic acid)/Carbon Nanotube Fibers as Novel Platforms for Glucose Biosensors

    OpenAIRE

    Valtencir Zucolotto; Eliton Souto Medeiros; Luiz Henrique Capparelli Mattoso; Juliano Elvis Oliveira

    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 to...

  5. Additive Manufacturing and Characterization of Polylactic Acid (PLA) Composites Containing Metal Reinforcements

    Science.gov (United States)

    Kuentz, Lily; Salem, Anton; Singh, M.; Halbig, M. C.; Salem, J. A.

    2016-01-01

    Additive manufacturing of polymeric systems using 3D printing has become quite popular recently due to rapid growth and availability of low cost and open source 3D printers. Two widely used 3D printing filaments are based on polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) systems. PLA is much more environmentally friendly in comparison to ABS since it is made from renewable resources such as corn, sugarcane, and other starches as precursors. Recently, polylactic acid-based metal powder containing composite filaments have emerged which could be utilized for multifunctional applications. The composite filaments have higher density than pure PLA, and the majority of the materials volume is made up of polylactic acid. In order to utilize functionalities of composite filaments, printing behavior and properties of 3-D printed composites need to be characterized and compared with the pure PLA materials. In this study, pure PLA and composite specimens with different metallic reinforcements (Copper, Bronze, Tungsten, Iron, etc) were 3D printed at various layer heights and resulting microstructures and properties were characterized. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) behavior of filaments with different reinforcements were studied. The microscopy results show an increase in porosity between 3-D printed regular PLA and the metal composite PLA samples, which could produce weaker mechanical properties in the metal composite materials. Tensile strength and fracture toughness behavior of specimens as a function of print layer height will be presented.

  6. Preparation and characterization of dry method esterified starch/polylactic acid composite materials.

    Science.gov (United States)

    Zuo, Yingfeng; Gu, Jiyou; Yang, Long; Qiao, Zhibang; Tan, Haiyan; Zhang, Yanhua

    2014-03-01

    Corn starch and maleic anhydride were synthesized from a maleic anhydride esterified starch by dry method. Fourier transform infrared spectroscopy (FTIR) was used for the qualitative analysis of the esterified starches. The reaction efficiency of dry method esterified starch reached 92.34%. The dry method esterified starch was blended with polylactic acid (PLA), and the mixture was melted and extruded to produce the esterified starch/polylactic acid (ES/PLA) composites. The degree of crystallinity of the ES/PLA was lower than that of the NS/PLA, indicating that the relative dependence between these two components of starch and polylactic acid was enhanced. Scanning electron microscopy (SEM) indicated that the dry method esterified starch increased the two-phase interface compatibility of the composites, thereby improving the tensile strength, bending strength, and elongation at break of the ES/PLA composite. The introduction of a hydrophobic ester bond and increase in interface compatibility led to an increase in ES/PLA water resistance. Melt index determination results showed that starch esterification modification had improved the melt flow properties of starch/PLA composite material. Strain scanning also showed that the compatibility of ES/PLA was increased. While frequency scanning showed that the storage modulus and complex viscosity of ES/PLA was less than that of NS/PLA. PMID:24315947

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

    Science.gov (United States)

    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

  8. Synthesis of high molecular weight polylactic acid from aqueous lactic acid co-catalyzed by tin(II)chloride dihydrate and succinic anhydride

    Institute of Scientific and Technical Information of China (English)

    LEI Ziqiang; BAI Yanbin; WANG Shoufeng

    2005-01-01

    Polylactic acid was synthesized from commercial available cheap aqueous lactic acid (85%―90% w/w) using succinic anhydride and SnCl2·2H2O as catalyst in the absence of organic solvents. As a result, polylactic acid with a molecular weight of 60000 was prepared in 10 h. The new procedure is much simple, cheap and outstanding in that the start material is aqueous lactic acid; the catalytic system is environmentally benign.

  9. Preparation and characterization of composites based on poly(lactic acid) and CaCO{sub 3} nanofiller

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Janaína Fernandes; Silva, Ana Lúcia N. da, E-mail: janamoreno.quim@gmail.com, E-mail: ananazareth@ima.ufrj.br [Instituto de Macromoléculas Professora Eloisa Mano - IMA/UFRJ – Brasil, Rio de Janeiro – RJ (Brazil); Silva, Antonio Henrique Monteiro da Fonseca T. da, E-mail: antoniohmfts@id.uff.br [Departamento Agrícola e Meio Ambiente – UFF – Brasil, Niterói – RJ (Brazil); Sousa, Ana Maria F. de, E-mail: ana.furtado.souza@gmail.com [Instituto de Química da Universidade - IQ/UERJ – Brasil, Rio de Janeiro – RJ (Brazil)

    2015-05-22

    In recent years, extensive studies have been conducted on the study of the poly(lactic acid) (PLA) properties, because of its being a typical biobased and biodegradable polymer, with good mechanical properties. However, its toughness and gas barrier properties are not satisfactory and can be improved by the addition of nanofillers, such as calcium carbonate (n-CaCO{sub 3}). The present work PLA composites with nano-sized precipitated calcium carbonate (n-NPCC) were prepared by melt extrusion. Thermal, mechanical and flow properties of the composites were evaluated by using a factorial design.The results showed that the addition of the nanofiller in the PLA matrix didn’t improve thethermal and mechanical properties of the matrix significantly. This behavior is probably due to the presence of the stearic acid that is coating on the n-NPCC particles, resulting in a weak polymer-particle interaction. Beyond this, it was also observed a decrease in MFI of the composites when nanofiller was added and at a higher screw speed.

  10. Preparation and characterization of composites based on poly(lactic acid) and CaCO3 nanofiller

    International Nuclear Information System (INIS)

    In recent years, extensive studies have been conducted on the study of the poly(lactic acid) (PLA) properties, because of its being a typical biobased and biodegradable polymer, with good mechanical properties. However, its toughness and gas barrier properties are not satisfactory and can be improved by the addition of nanofillers, such as calcium carbonate (n-CaCO3). The present work PLA composites with nano-sized precipitated calcium carbonate (n-NPCC) were prepared by melt extrusion. Thermal, mechanical and flow properties of the composites were evaluated by using a factorial design.The results showed that the addition of the nanofiller in the PLA matrix didn’t improve thethermal and mechanical properties of the matrix significantly. This behavior is probably due to the presence of the stearic acid that is coating on the n-NPCC particles, resulting in a weak polymer-particle interaction. Beyond this, it was also observed a decrease in MFI of the composites when nanofiller was added and at a higher screw speed

  11. Preparation and characterization of composites based on poly(lactic acid) and CaCO3 nanofiller

    Science.gov (United States)

    Moreno, Janaína Fernandes; da Silva, Ana Lúcia N.; da Silva, Antonio Henrique Monteiro da Fonseca T.; de Sousa, Ana Maria F.

    2015-05-01

    In recent years, extensive studies have been conducted on the study of the poly(lactic acid) (PLA) properties, because of its being a typical biobased and biodegradable polymer, with good mechanical properties. However, its toughness and gas barrier properties are not satisfactory and can be improved by the addition of nanofillers, such as calcium carbonate (n-CaCO3). The present work PLA composites with nano-sized precipitated calcium carbonate (n-NPCC) were prepared by melt extrusion. Thermal, mechanical and flow properties of the composites were evaluated by using a factorial design.The results showed that the addition of the nanofiller in the PLA matrix didn't improve thethermal and mechanical properties of the matrix significantly. This behavior is probably due to the presence of the stearic acid that is coating on the n-NPCC particles, resulting in a weak polymer-particle interaction. Beyond this, it was also observed a decrease in MFI of the composites when nanofiller was added and at a higher screw speed.

  12. Polymer blends of polylactic acid (PLA) and polybutylene succinate-adipate

    Science.gov (United States)

    Ma, Wenguang

    A series of blends consisting of polylactic acid (PLA) and aliphatic succinate polyester (BionolleRTM #3000) had been prepared and investigated. The results of mechanical property investigations showed that using 20 wt% Bionolle#3000 can significantly increase the toughness of PLA. BionolleRTM #3000 also reduces the physical aging rate of PLA so blends remain tough longer. Conversely, the stiffness of BionolleRTM #3000 can be significantly increased by blending in PLA. DMA and DSC results show that PLA/BionolleRTM 3000 blends are not thermodynamically miscible, but are compatible blends. Studies have also been performed to determine the amount and rate of aerobic biodegradation of PLA/aliphatic succinate polyester blends in biologically active composting, enzymatic, and soil environments. The changes in molecular weight, molecular structure and thermal properties in the composting environment were also studied by GPC, NMR and DSC analyses. The research results showed BionolleRTM #3000 had a high degradation rate, while PLA had a low degradation rate. PLA/BionolleRTM #3000 blends had moderate degradation rates that increased with BionolleRTM #3000 content. The melt flow behavior of PLA/BionolleRTM #3000 blends has been studied by capillary rheometry. The relationship of the blends' viscosity with their composition, shear stress, shear rate, and temperature has been investigated. Power law index and activation energy of PLA, BionolleRTM #3000 and their blends have been calculated. The experimental and theoretical data can let us understand the processability of PLA/BionolleRTM #3000 blends. A scanning electron microscope (SEM) was used to investigate the morphological structure of the PLA/BionolleRTM #3000 blends. Micrographs of the samples made from different methods (blown film, extrudate and compression molding sheet) were taken; their differences in morphology were compared. For comparison, the micrographs of blend PLA/BionolleRTM #6000 was also studied. The

  13. Effects of gas atmospheres on poly(lactic acid) film in acrylic acid plasma treatment

    International Nuclear Information System (INIS)

    Plasma polymerized acrylic acid (AA) coatings were deposited on poly(lactic acid) (PLA) films in various gas atmospheres during the pre-treatment of PLA and the deposition of AA, respectively. Therefore, this work was twofold: the argon pretreated PLA films followed by a deposition in argon were investigated against the mixture of argon and oxygen pretreated ones under the same deposition conditions; the plasma deposition of AA operating in different atmospheres (argon, oxygen and nitrogen) was employed to modify the pretreated PLA in oxygen. Chemical and physical changes on the plasma-treated surfaces were examined using contact angle, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and attenuated total reflection infrared (ATR-FTIR) analysis. The results showed that the discharge gas can have a significant influence on the chemical composition of the PLA surfaces: oxygen plasmas introduced oxygen-containing groups in company with surface etching in pretreatment and deposition, while argon discharges was able to achieve much better hydrophilic behavior and high retention ratio of poly(acrylic acid) (PAA) coating before and after washing in water.

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

    Science.gov (United States)

    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.

  15. Effects of gas atmospheres on poly(lactic acid) film in acrylic acid plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yun, E-mail: yun.zhaotju@yahoo.com [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy); Fina, Alberto [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino – sede di Alessandria, V. T. Michel 5, 15121 Alessandria (Italy); Venturello, Alberto; Geobaldo, Francesco [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy)

    2013-10-15

    Plasma polymerized acrylic acid (AA) coatings were deposited on poly(lactic acid) (PLA) films in various gas atmospheres during the pre-treatment of PLA and the deposition of AA, respectively. Therefore, this work was twofold: the argon pretreated PLA films followed by a deposition in argon were investigated against the mixture of argon and oxygen pretreated ones under the same deposition conditions; the plasma deposition of AA operating in different atmospheres (argon, oxygen and nitrogen) was employed to modify the pretreated PLA in oxygen. Chemical and physical changes on the plasma-treated surfaces were examined using contact angle, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and attenuated total reflection infrared (ATR-FTIR) analysis. The results showed that the discharge gas can have a significant influence on the chemical composition of the PLA surfaces: oxygen plasmas introduced oxygen-containing groups in company with surface etching in pretreatment and deposition, while argon discharges was able to achieve much better hydrophilic behavior and high retention ratio of poly(acrylic acid) (PAA) coating before and after washing in water.

  16. Biodegradable polyesters based on succinic acid

    Directory of Open Access Journals (Sweden)

    Nikolić Marija S.

    2003-01-01

    Full Text Available Two series of aliphatic polyesters based on succinic acid were synthesized by copolymerization with adipic acid for the first series of saturated polyesters, and with fumaric acid for the second series. Polyesters were prepared starting from the corresponding dimethyl esters and 1,4-butanediol by melt transesterification in the presence of a highly effective catalyst tetra-n-butyl-titanate, Ti(0Bu4. The molecular structure and composition of the copolyesters was determined by 1H NMR spectroscopy. The effect of copolymer composition on the physical and thermal properties of these random polyesters were investigated using differential scanning calorimetry. The degree of crystallinity was determined by DSC and wide angle X-ray. The degrees of crystallinity of the saturated and unsaturated copolyesters were generally reduced with respect to poly(butylene succinate, PBS. The melting temperatures of the saturated polyesters were lower, while the melting temperatures of the unsaturated copolyesters were higher than the melting temperature of PBS. The biodegradability of the polyesters was investigated by enzymatic degradation tests. The enzymatic degradation tests were performed in a buffer solution with Candida cylindracea lipase and for the unsaturated polyesters with Rhizopus arrhizus lipase. The extent of biodegradation was quantified as the weight loss of polyester films. Also the surface of the polyester films after degradation was observed using optical microscopy. It could be concluded that the biodegradability depended strongly on the degree of crystallinity, but also on the flexibility of the chain backbone. The highest biodegradation was observed for copolyesters containing 50 mol.% of adipic acid units, and in the series of unsaturated polyesters for copolyesters containing 5 and 10 mol.% of fumarate units. Although the degree of crystallinity of the unsaturated polyesters decreased slightly with increasing unsaturation, the biodegradation

  17. Protective effect of recombinant staphylococcal enterotoxin A entrapped in polylactic-co-glycolic acid microspheres against Staphylococcus aureus infection

    Directory of Open Access Journals (Sweden)

    Chen Liben

    2012-03-01

    Full Text Available Abstract Staphylococcus aureus is an important cause of nosocomial and community-acquired infections in humans and animals, as well as the cause of mastitis in dairy cattle. Vaccines aimed at preventing S. aureus infection in bovine mastitis have been studied for many years, but have so far been unsuccessful due to the complexity of the bacteria, and the lack of suitable vaccine delivery vehicles. The current study developed an Escherichia coli protein expression system that produced a recombinant staphylococcal enterotoxin A (rSEA encapsulated into biodegradable microparticles generated by polylactic-co-glycolic acid (PLGA dissolved in methylene chloride and stabilized with polyvinyl acetate. Antigen loading and surface properties of the microparticles were investigated to optimize particle preparation protocols. The prepared PLGA-rSEA microspheres had a diameter of approximately 5 μm with a smooth and regular surface. The immunogenicity of the PLGA-rSEA vaccine was assessed using mice as an animal model and showed that the vaccine induced a strong humoral immune response and increased the percent survival of challenged mice and bacterial clearance. Histological analysis showed moderate impairment caused by the pathogen upon challenge afforded by immunization with PLGA-rSEA microspheres. Antibody titer in the sera of mice immunized with PLGA-rSEA microparticles was higher than in vaccinated mice with rSEA. In conclusion, the PLGA-rSEA microparticle vaccine developed here could potentially be used as a vaccine against enterotoxigenic S. aureus.

  18. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats.

    Science.gov (United States)

    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

  19. Sterilization, toxicity, biocompatibility and clinical applications of polylactic acid/polyglycolic acid copolymers.

    Science.gov (United States)

    Athanasiou, K A; Niederauer, G G; Agrawal, C M

    1996-01-01

    This is a review of salient studies of sterilization, toxicity, biocompatibility, clinical applications and current work in the field of orthopaedics, using implants made of polylactic acid (PLA), polyglycolic acid (PGA) and their copolymers. The intrinsic nature of these biomaterials renders them suitable for applications where temporally slow releases of bioactive agents in situ may be required. They are also desirable as fixation devices of bone, because they can virtually eliminate osteopenia associated with stress shielding or additional surgery. The majority of currently available sterilization techniques are not suitable for these thermoplastic materials and it may be desirable to develop new sterilization standards, which can account for the special character of PLA-PGA materials. Biocompatibility and toxicity studies suggest that, overall, PLA-PGA biomaterials may be suitable for orthopaedic applications, although certain problems, especially pertaining to reduction in cell proliferation, have been reported. Clinical applications are also promising, albeit not without problems usually associated with transient tissue inflammation. The future of these materials appears bright, especially in soft tissues. They may be used to address the exceedingly complex problem of osteochondral repair, but also as a means to enhance fixation and repair processes in tendons and ligaments. PMID:8624401

  20. Biodegradation of chlorobenzoic acids by ligninolytic fungi

    Czech Academy of Sciences Publication Activity Database

    Muzikář, Milan; Křesinová, Zdena; Svobodová, Kateřina; Filipová, Alena; Čvančarová, Monika; Cajthamlová, Kamila; Cajthaml, Tomáš

    2011-01-01

    Roč. 196, - (2011), s. 386-394. ISSN 0304-3894 R&D Projects: GA MŠk 2B06156; GA ČR GA525/09/1058 Institutional research plan: CEZ:AV0Z50200510 Keywords : Chlorobenzoic acid * Polychlorinated biphenyls * Biodegradation Subject RIV: EE - Microbiology, Virology Impact factor: 4.173, year: 2011

  1. Chopped basalt fibres: A new perspective in reinforcing poly(lactic acid to produce injection moulded engineering composites from renewable and natural resources

    Directory of Open Access Journals (Sweden)

    P. Tamas

    2013-02-01

    Full Text Available This paper focuses on the reinforcing of Poly(lactic acid with chopped basalt fibres by using silane treated and untreated basalt fibres. Composite materials with 5–10–15–20–30–40 wt% basalt fibre contents were prepared from silane sized basalt fibres using extrusion, and injection moulding, while composites with 5–10–15 wt% basalt fibre contents were also prepared by using untreated basalt fibres as control. The properties of the injection moulded composites were extensively examined by using quasi-static (tensile, three-point bending and dynamic mechanical tests (notched and unnotched Charpy impact tests, dynamic mechanical analysis (DMA, differential scanning calorimetry (DSC, heat deflection temperature (HDT analysis, dimensional stability test, as well as melt flow index (MFI analysis and scanning electron microscopic (SEM observations. It was found that silane treated chopped basalt fibres are much more effective in reinforcing Poly(lactic acid than natural fibres; although basalt fibres are not biodegradable but they are still considered as natural (can be found in nature in the form of volcanic rocks and biologically inert. It is demonstrated in this paper that by using basalt fibre reinforcement, a renewable and natural resource based composite can be produced by injection moulding with excellent mechanical properties suitable even for engineering applications. Finally it was shown that by using adequate drying of the materials, composites with higher mechanical properties can be achieved compared to literature data.

  2. Application of vibrational spectroscopy in the in vitro studies of carbon fiber-polylactic acid composite degradation.

    Science.gov (United States)

    Blazewicz, Marta; Gajewska, Maria Chomyszyn; Paluszkiewicz, Czeslawa

    1999-05-01

    Vibrational spectroscopy was used for assessment of new material for stomatology, for guided tissue regeneration (GTR) techniqe.Implants applied in the healing of periodontal defects using GTR technique have to meet stringent requirements concerning their chemical as well physical properties.At present the implants prepared from two layers membranes differing in porosity in their outer and inner layers are studied clinically. Composite plates prepared by us consist of three layers: polylactic acid film, carbon fibres coated with polylactic acid and carbon fabric.Vibrational spectroscopic studies of the material; polylactic acid- carbon fiber have made it possible to analyse chemical reactions occurring between the polymer and carbon surface. Analysis of the IR spectra of samples treated in Ringer solution allowed to describe the phenomena resulting from the composite degradation. It was shown that material biostability is related to the presence of carbon fibers.

  3. Processing and Characterization of Cellulose Nanocrystals/Polylactic Acid Nanocomposite Films

    Directory of Open Access Journals (Sweden)

    Erin M. Sullivan

    2015-12-01

    Full Text Available The focus of this study is to examine the effect of cellulose nanocrystals (CNC on the properties of polylactic acid (PLA films. The films are fabricated via melt compounding and melt fiber spinning followed by compression molding. Film fracture morphology, thermal properties, crystallization behavior, thermo-mechanical behavior, and mechanical behavior were determined as a function of CNC content using scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, dynamic mechanical analysis, and tensile testing. Film crystallinity increases with increasing CNC content indicating CNC act as nucleating agents, promoting crystallization. Furthermore, the addition of CNC increased the film storage modulus and slightly broadened the glass transition region.

  4. Analysis of Gas Permeability Characteristics of Poly(Lactic Acid)/Poly(Butylene Succinate) Nanocomposites

    OpenAIRE

    Amita Bhatia; Rahul K Gupta; Bhattacharya, Sati N.; Hyoung Jin Choi

    2012-01-01

    Gas permeability and morphological properties of nanocomposites prepared by the mixing of poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and clay was investigated. While the composition of PLA and PBS polymers was fixed as 80% and 20% by weight, respectively, for all the nanocomposites, clay contents varied from 1 to 10 wt%. From the morphological studies using both wide angle X-ray diffraction and transmission electron microscopy, the nanocomposite having 1 wt% of clay was consider...

  5. Distribution and Orientation of Carbon Fibers in Polylactic Acid Parts Produced by Fused Deposition Modeling

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; W. Gutmann, Ingomar; Koch, Thomas;

    2016-01-01

    The aim of this paper is the understanding of the fiber orientation by investigations in respect to the inner configuration of a polylactic acid matrix reinforced with short carbon fibers after a fused deposition modeling extrusion process. The final parts were analyzed by X-ray, tomography, and ...... magnetic resonance imaging allowing a resolved orientation of the fibers and distribution within the part. The research contributes to the understanding of the fiber orientation and fiber reinforcement of fused deposition modeling parts in additive manufacturing....

  6. Processing and characterization of poly(lactic acid) based bioactive composites for biomedical scaffold application

    OpenAIRE

    Goswami, J.; Ghosh, A. K.; Bhatnagar, N; Mohanty, S.

    2013-01-01

    The current study focuses on three-components material systems (poly(lactic acid) (PLA), poly(ε-caprolactone) (PCL) and wollastonite (W)) in view of possible application a biomedical scaffold constructs. Melt extruded PLA/PCL/W composites (PLCL15, PLCLW1, PLCLW4, PLCLW8 containing 0, 1, 4, 8 phr filler respectively) are batch foamed using compressed CO2 and the porous foams are studied for in vitro biocompatibility by seeding osteoblast cells. SEM images of the unfoamed polymers show imm...

  7. Biodegradability Evaluation of Polymers by ISO 14855-2

    OpenAIRE

    Masao Kunioka; Fumi Ninomiya; Masahiro Funabashi

    2009-01-01

    Biodegradabilities of polymers and their composites in a controlled compost were described. Polycaprolactone (PCL) and poly(lactic acid) (PLA) were employed as biodegradable polymers. Biodegradabilities of PCL and PLA samples in a controlled compost were measured using a Microbial Oxidative Degradation Analyzer (MODA) according to ISO 14855-2. Sample preparation method for biodegradation test according to ISO/DIS 10210 was also described. Effects of sizes and shapes of samples on biodegradabi...

  8. Kinetics and mechanism of the biodegradation of PLA/clay nanocomposites during thermophilic phase of composting process

    Czech Academy of Sciences Publication Activity Database

    Stloukal, P.; Pekařová, S.; Kalendová, A.; Mattausch, H.; Laske, S.; Holzer, C.; Chitu, L.; Bodner, S.; Maier, G.; Šlouf, Miroslav; Koutný, M.

    2015-01-01

    Roč. 42, August (2015), s. 31-40. ISSN 0956-053X Institutional support: RVO:61389013 Keywords : composting * biodegradability * polylactic acid Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.220, year: 2014

  9. Poly(lactic acid/Carbon Nanotube Fibers as Novel Platforms for Glucose Biosensors

    Directory of Open Access Journals (Sweden)

    Valtencir Zucolotto

    2012-02-01

    Full Text Available 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.

  10. Surface Functional Poly(lactic Acid Electrospun Nanofibers for Biosensor Applications

    Directory of Open Access Journals (Sweden)

    Edurne González

    2016-01-01

    Full Text Available In this work, biotin surface functionalized hydrophilic non-water-soluble biocompatible poly(lactic acid (PLA nanofibers are created for their potential use as biosensors. Varying concentrations of biotin (up to 18 weight total percent (wt % were incorporated into PLA fibers together with poly(lactic acid-block-poly(ethylene glycol (PLA-b-PEG block polymers. While biotin provided surface functionalization, PLA-b-PEG provided hydrophilicity to the final fibers. Morphology and surface-available biotin of the final fibers were studied by Field Emission Scanning Electron Microscopy (FESEM and competitive colorimetric assays. The incorporation of PLA-b-PEG block copolymers not only decreased fiber diameters but also dramatically increased the amount of biotin available at the fiber surface able to bind avidin. Finally, fiber water stability tests revealed that both biotin and PLA-b-PEG, migrated to the aqueous phase after relatively extended periods of water exposure. The functional hydrophilic nanofiber created in this work shows a potential application as a biosensor for point-of-care diagnostics.

  11. MWCNTs-reinforced epoxidized linseed oil plasticized polylactic acid nanocomposite and its electroactive shape memory behaviour.

    Science.gov (United States)

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-01-01

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy "U"-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices. PMID:25365179

  12. MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

    Directory of Open Access Journals (Sweden)

    Javed Alam

    2014-10-01

    Full Text Available A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA was first plasticized by epoxidized linseed oil (ELO in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %, with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC, tensile test, and thermo gravimetric analysis (TGA. Scanning electron microscopy (SEM and atomic force microscopy (AFM were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

  13. Water vapour permeability of poly(lactic acid): Crystallinity and the tortuous path model

    Science.gov (United States)

    Duan, Z.; Thomas, N. L.

    2014-02-01

    The water vapour transmission rates (WVTR) through samples of polylactic acid of different crystallinities have been measured. Three different grades of commercial poly(lactic acid) (PLA) were used with different ratios of L-lactide and D-lactide to give a range of crystallinities from 0% to 50%. Sheets of PLA were prepared by melt compounding followed by compression moulding and annealing at different temperatures and for different times to give the range of crystallinities required. Crystallinity was measured by differential scanning calorimetry and the morphology of the samples was observed under crossed polars in a transmitted light microscope. Water vapour transmission rates through the films were measured at 38 °C and at a relative humidity of 90%. It was found that the measured values of WVTR decreased linearly with increasing crystallinity of the PLA from 0% to 50%. The results are discussed in terms of the effect of crystallinity on solubility and shown to fit the "Tortuous Path Model." The model was also successfully used to explain published data on water permeability of polyethylene terephthalate.

  14. Polylactic-co-glycolic acid microspheres containing three neurotrophic factors promote sciatic nerve repair after injury

    Institute of Scientific and Technical Information of China (English)

    Qun Zhao; Zhi-yue Li; Ze-peng Zhang; Zhou-yun Mo; Shi-jie Chen; Si-yu Xiang; Qing-shan Zhang; Min Xue

    2015-01-01

    A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neuro-trophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site;their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the micro-spheres at 300-µm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implanta-tion, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve ifbers were observed and dis-tributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.

  15. Endothelial Differentiation of Human Adipose-Derived Stem Cells on Polyglycolic Acid/Polylactic Acid Mesh

    Directory of Open Access Journals (Sweden)

    Meng Deng

    2015-01-01

    Full Text Available Adipose-derived stem cell (ADSC is considered as a cell source potentially useful for angiogenesis in tissue engineering and regenerative medicine. This study investigated the growth and endothelial differentiation of human ADSCs on polyglycolic acid/polylactic acid (PGA/PLA mesh compared to 2D plastic. Cell adhesion, viability, and distribution of hADSCs on PGA/PLA mesh were observed by CM-Dil labeling, live/dead staining, and SEM examination while endothelial differentiation was evaluated by flow cytometry, Ac-LDL/UEA-1 uptake assay, immunofluorescence stainings, and gene expression analysis of endothelial related markers. Results showed hADSCs gained a mature endothelial phenotype with a positive ratio of 21.4 ± 3.7% for CD31+/CD34− when induced in 3D mesh after 21 days, which was further verified by the expressions of a comprehensive range of endothelial related markers, whereas hADSCs in 2D induced and 2D/3D noninduced groups all failed to differentiate into endothelial cells. Moreover, compared to 2D groups, the expression for α-SMA was markedly suppressed in 3D cultured hADSCs. This study first demonstrated the endothelial differentiation of hADSCs on the PGA/PLA mesh and pointed out the synergistic effect of PGA/PLA 3D culture and growth factors on the acquisition of mature characteristic endothelial phenotype. We believed this study would be the initial step towards the generation of prevascularized tissue engineered constructs.

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

    Science.gov (United States)

    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.

  17. Electrospun poly(lactic acid) based conducting nanofibrous networks

    International Nuclear Information System (INIS)

    Multi-functionalised micro/nanostructures of conducting polymers in neat or blended forms have received much attention because of their unique properties and technological applications in electrical, magnetic and biomedical devices. Biopolymer-based conducting fibrous mats are of special interest for tissue engineering because they not only physically support tissue growth but also are electrically conductive, and thus are able to stimulate specific cell functions or trigger cell responses. They are effective for carrying current in biological environments and can thus be considered for delivering local electrical stimuli at the site of damaged tissue to promote wound healing. Electrospinning is an established way to process polymer solutions or melts into continuous fibres with diameter often in the nanometre range. This process primarily depends on a number of parameters, including the type of polymer, solution viscosity, polarity and surface tension of the solvent, electric field strength and the distance between the spinneret and the collector. The present research has included polyaniline (PANi) as the conducting polymer and poly(L-lactic acid) (PLLA) as the biopolymer. Dodecylbenzene sulphonic acid (DBSA) doped PANi and PLLA have been dissolved in a common solvent (mixtures of chloroform and dimethyl formamide (DMF)), and the solutions successfully electrospun. DMF enhanced the dielectric constant of the solvent, and tetra butyl ammonium bromide (TBAB) was used as an additive to increase the conductivity of the solution. DBSA-doped PANi/PLLA mat exhibits an almost bead-free network of nanofibres that have extraordinarily smooth surface and diameters in the range 75 to 100 nm.

  18. Production and characterization of 166Ho polylactic acid microspheres.

    Science.gov (United States)

    Yavari, Kamal; Yeganeh, Ehsan; Abolghasemi, Hossein

    2016-01-01

    Microsphere and particle technology with selective transport of radiation represents a new generation of therapeutics. Poly-L-lactic acid (PLLA) microspheres loaded with holmium-166 acetylacetonate ((166)Ho-PLLA-MS) are novel microdevices. In this research, (165)HoAcAc-PLLA microparticles were prepared by the solvent evaporation technique. Microspheres were irradiated at Tehran Research Reactor. The diameter and surface morphologies were characterized by particle sizer and scanning electron microscopy before and after irradiation. The complex stability, radiochemical purity, and in vivo biodistribiotion were checked in the final solution up to 3 days. In this study, (166)Ho-PLLA spherical particles with a smooth surface and diameter of 20-40 µm were obtained, which were stable in vitro and in vivo studies. Neutron irradiation did not damage the particles. The ease with which the PLLA spheres could be made in the optimal size range for later irradiation and their ability to retain the (166)Ho provided good evidence for their potential use in radioembolization. PMID:26691104

  19. Functionalized graphene with polymer toughener as novel interface modifier for property-tailored poly(lactic acid)/graphene nanocomposites

    Science.gov (United States)

    In this work, an effective strategy for engineering the interfacial compatibility between graphene and polylactic acid (PLA) was developed by manipulating the functionalization of graphene and introducing an epoxy-containing elastomer modifier. Curing between the functional groups of the modified gr...

  20. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/ polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

    Science.gov (United States)

    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...

  1. Performance enhancement of poly(lactic acid)/soy protein concentrate blends by promoting formation of network structure

    Science.gov (United States)

    In this work, the effects of water content in preformulated soy protein concentrate (SPC) and of SPC content on the thermal, rheological and mechanical properties and morphology of poly(lactic acid) (PLA)/SPC blends were studied. The blends were prepared by twin screw compounding and the test specim...

  2. Antibacterial poly(lactic acid) (PLA) films grafting electrospun PLA/Ally isothioscyanate (AITC) fibers for food packaging

    Science.gov (United States)

    Poly(lactic acid) (PLA) fibers of submicron sizes encapsulating allyl isothiocyanate (AITC) (PfA) were made and electrospun onto the surfaces of PLA films (PfA-g-film). SEM examination confirmed that the fibers were grafted to the PLA film after the (PfA-g-film) underwent air blowing and water washi...

  3. Phase structure evolution during mixing and processing of poly(lactic acid)/polycaprolactone (PLA/PCL) blends

    Czech Academy of Sciences Publication Activity Database

    Fortelný, Ivan; Ostafinska, Aleksandra; Michálková, Danuše; Jůza, Josef; Mikešová, Jana; Šlouf, Miroslav

    2015-01-01

    Roč. 72, č. 11 (2015), s. 2931-2947. ISSN 0170-0839 R&D Projects: GA ČR(CZ) GA14-17921S; GA ČR GAP106/11/1069 Institutional support: RVO:61389013 Keywords : polymer blends * morphology evolution * poly(lactic acid) Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.438, year: 2014

  4. Preparation and characterization of aligned carbon nanotubes/polylactic acid composite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kong Yuxia; Yuan Jie [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Qiu Jun, E-mail: qiujun@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials of Education of Ministry, Shanghai 201804 (China)

    2012-07-01

    Aligned functionalized multiwalled carbon nanotubes/polylactic acid (MWNTs-PCL/PLA) composite fibers were successfully prepared by electrospinning processing. The MWNTs bonded with the polycaprolactone chains exhibited excellent uniform dispersion in PLA solution by comparing with the acid-functionalized MWNTs and amino-functionalized MWNTs. Optical microscopy was used to study the aligned degree of the fibers and to investigate the influences of the electrodes distance on the alignment and structure of the fibers, and results showed that the best quality of aligned fibers with dense structure and high aligned degree were obtained at an electrodes distance of 3 cm. Moreover, the MWNTs embedded inside the MWNTs-PCL/PLA fibers displayed well orientation along the axes of the fibers, which was demonstrated by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.

  5. Characterisation of solution cast cellulose nanofibre – reinforced poly(lactic acid

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available Cellulose nanofibres, 20 nm in diameter and 300 nm long, were prepared by acid hydrolysis of flax yarns. Composite films containing 2.5 and 5.0 wt% flax cellulose (FC fibres were prepared by solution casting of mixtures of poly(lactic acid (PLA solution and cellulose nanofibre suspension in chloroform. The resulting composite films and solution cast pure PLA film, with thickness of around 160 m, showed good transparency. For composites with 2.5 and 5.0 wt% FC, the tensile strength increased by 25 and 59% and tensile modulus by 42 and 47%, respectively, compared to pure PLA film. The composite film with 2.5 wt% FC combined high strength and ductility with tensile strength of 24.3 MPa and 70% elongation at break. Flax cellulose appeared to facilitate nucleation and subsequent crystallisation of PLA more effectively in the amorphous composites than in the crystalline composites.

  6. Morphologies, mechanical properties and thermal stability of poly(lactic acid) toughened by precipitated barium sulfate

    Science.gov (United States)

    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.

  7. Effects of Graphene Nanoplatelets and Reduced Graphene Oxide on Poly(lactic acid and Plasticized Poly(lactic acid: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Buong Woei Chieng

    2014-08-01

    Full Text Available The superlative mechanical properties of graphene-based materials make them the ideal filler materials for polymer composites reinforcement. Two types of graphene-based materials, graphene nanoplatelets (xGnP and reduced graphene oxide (rGO, were used as nanofiller in poly(lactic acid (PLA polymer matrix, as well as plasticized PLA. The addition of rGO into PLA or plasticized PLA substantially enhanced the tensile strength without deteriorating elasticity, compared to xGnP nanocomposites. In addition, the investigation of the thermal properties has found that the presence of rGO in the system is very beneficial for improving thermal stability of the PLA or plasticized PLA. Scanning electron microscope (SEM images of the rGO nanocomposites display homogenous and good uniformity morphology. Transmission electron microscopy (TEM images revealed that the rGO remained intact as graphene sheet layers and were dispersed well into the polymer matrix, and it was confirmed by X-ray diffraction (XRD results, which shows no graphitic peak in the XRD pattern.

  8. Bio-safe processing of polylactic-co-caprolactone and polylactic acid blends to fabricate fibrous porous scaffolds for in vitro mesenchymal stem cells adhesion and proliferation.

    Science.gov (United States)

    Salerno, Aurelio; Guarino, Vincenzo; Oliviero, Olimpia; Ambrosio, Luigi; Domingo, Concepción

    2016-06-01

    In this study, the design and fabrication of porous scaffolds, made of blends of polylactic-co-caprolactone (PLC) and polylactic acid (PLA) polymers, for tissue engineering applications is reported. The scaffolds are prepared by means of a bio-safe thermally induced phase separation (TIPS) approach with or without the addition of NaCl particles used as particulate porogen. The scaffolds are characterized to assess their crystalline structure, morphology and mechanical properties, and the texture of the pores and the pore size distribution. Moreover, in vitro human mesenchymal stem cells (hMSCs) culture tests have been carried out to demonstrate the biocompatibility of the scaffolds. The results of this study demonstrate that all of the scaffold materials processed by means of TIPS process are semi-crystalline. Furthermore, the blend composition affected polymer crystallization and, in turn, the nano and macro-structural properties of the scaffolds. Indeed, neat PLC and neat PLA crystallize into globular and randomly arranged sub micro-size scale fibrous conformations, respectively. Concomitantly, the addition of NaCl particles during the fabrication route allows for the creation of an interconnected network of large pores inside the primary structure while resulted in a significant decrease of scaffolds mechanical response. Finally, the results of cell culture tests demonstrate that both the micro and macro-structure of the scaffold affect the in vitro hMSCs adhesion and proliferation. PMID:27040246

  9. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding

    International Nuclear Information System (INIS)

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. - Highlights: • Microcellular injection molding was used to fabricate tissue engineering scaffolds. • TPU/PLA tissue engineering scaffolds with tunable properties were fabricated. • Multiple test methods were used to characterize the scaffolds. • The biocompatibility of the scaffolds was confirmed by fibroblast cell culture. • Scaffolds produced have the potential to be used in multiple tissue applications

  10. Modeling of hyaluronic acid containing anti-cancer drugs-loaded polylactic-co-glycolic acid bioconjugates for targeted delivery to cancer cells

    Science.gov (United States)

    Gul-e-Saba, Adulphakdee, A.; Madthing, A.; Zafar, M. N.; Abdullah, M. A.

    2012-09-01

    Molecular modeling of hyaluronan (HA), polylactic-co-glycolic acid (PLGA), polyethylene glycol-bis-amine (PEG-bis-amine), Curcumin, Cisplatin and the conjugate HA-PEG-PLGA containing Curcumin/Cisplatin were performed using Discovery Studio 2.5 to better understand issues and constraints related to targeted delivery of potent anticancer drugs to cancer cells. HA, a versatile biopolymer is a ligand of cancer cell receptor, CD44 that can be particularly useful in a receptor-mediated cellular uptake of drug-incorporated nanoparticles. Biocompatible and biodegradable polymers, PLGA and PEG, serve as polymeric micelles for controlled-release of drug. Curcumin as a natural anticancer agent has poor solubility that limits its use in drug therapeutics, while platinum-based Cisplatin exhibits systemic cytotoxicity. These can be overcome via drug delivery in polymeric biocompatible vehicles. The PLGA-PEG-HA conjugate shows the total measurement of 105 bond length with average bond length of 1.274163 Å. The conjugation between PEG and HA occurs at C8-O1 atoms and can be manipulated to improve properties.

  11. Effect of synthetic mica on the thermal properties of poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Diego Holanda Saboya Souza

    2014-01-01

    Full Text Available Poly(lactic acid/Somasif fluoromica nanocomposites were prepared by melt blending and their thermal properties investigated by DSC, TGA and DMA. Three different types of synthetic mica (Somasif ME-100, Somasif MAE and Somasif MPE were used at different contents (2.5, 5.0 and 7.5 wt %. The melt blending of PLA and these micas is characterized by a considerable reduction in the matrix molecular weight, which decreases when the nanofiller content is increased. For all nanocomposites, the thermal stability increases when mica is added to the polymer, with the Somasif MPE, producing the highest increase of the degradation temperature and highest reduction of Tg.

  12. A review of poly(lactic acid)-based materials for antimicrobial packaging.

    Science.gov (United States)

    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

  13. Nanostructured Polylactic Acid/Candeia Essential Oil Mats Obtained by Electrospinning

    Directory of Open Access Journals (Sweden)

    Cláudia L. S. de Oliveira Mori

    2015-01-01

    Full Text Available This work aims to evaluate the effect of inclusion of different contents of candeia (Eremanthus erythropappus essential oil (whose alpha-bisabolol is the main terpene on the properties of polylactic acid (PLA nanostructured mats and their relationship with fiber morphology and structure. The interaction occurring between the PLA and the candeia essential oil was confirmed by thermal and microscopy analysis. Addition of candeia essential oil increased nanofiber diameter and decreased the glass transition and melting temperatures of the nanofibers, suggesting lower energy input for processing. Scanning electron microscopy (SEM images provided evidence of a homogeneous structure for the nanostructured mats. X-ray diffraction did not show differences in the crystallization of the nanofibers. This ongoing research confirms the possibility of incorporation of candeia essential oil in the production of nanofibers that will be studied for multipurpose applications.

  14. A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning

    Science.gov (United States)

    Thu Trang Mai, Thi; Thu Thuy Nguyen, Thi; Duong Le, Quang; Ngoan Nguyen, Thi; Cham Ba, Thi; Binh Nguyen, Hai; Bich Hoa Phan, Thi; Tran, Dai Lam; Phuc Nguyen, Xuan; Park, Jun Seo

    2012-06-01

    Curcumin (Cur), extracted from the Curcuma longa L. plant, is well known for its anti-tumor, anti-oxidant, anti-inflammatory and anti-bacterial properties. Nanofiber mats of polylactic acid (PLA) loading Cur (5 wt%) were fabricated by electrospinning (e-spinning). Morphology and structure of the fibers were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The diameters of the obtained fibers varied from 200 to 300 nm. The release capacity of curcumin from curcumin-loaded PLA fibers was investigated in phosphate buffer saline (PBS) containing ethanol. After 24 h, 50% of the curcumin was released from curcumin-loaded PLA fibers. These results of electrospun (e-spun) fibers exhibit the potential for biomedical application.

  15. Effect of Fermented Chitin Nano whiskers on Properties of Polylactic Acid Bio composite Films

    International Nuclear Information System (INIS)

    The fermented chitin nano whiskers (FCNW) filled polylactic acid (PLA) bio composite films were successfully produced using solution casting method. The bio composite films were characterized in terms of tensile properties. The Young's modulus increased with increasing FCNW content while the tensile strength increased and reached the maximum value at 4 phr FCNW loading. Therefore it can be concluded that the optimum loading of FCNW is at 4 phr and further addition of FCNW may lead to agglomeration resulting in a decrease in tensile strength. The elongation at break of the bio composite films decreased rapidly upon addition of FCNW into PLA. From the Atomic Force Microscopy, the surface morphology of the PLA changed upon addition of FCNW and tendency for agglomeration of FCNW at high loading was observed. (author)

  16. Clay-filled bio-based blends of poly(lactic acid) and polyamide 11

    Science.gov (United States)

    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.

  17. Influence of different sterilization processes on the properties of commercial poly(lactic acid).

    Science.gov (United States)

    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

  18. A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning

    International Nuclear Information System (INIS)

    Curcumin (Cur), extracted from the Curcuma longa L. plant, is well known for its anti-tumor, anti-oxidant, anti-inflammatory and anti-bacterial properties. Nanofiber mats of polylactic acid (PLA) loading Cur (5 wt%) were fabricated by electrospinning (e-spinning). Morphology and structure of the fibers were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The diameters of the obtained fibers varied from 200 to 300 nm. The release capacity of curcumin from curcumin-loaded PLA fibers was investigated in phosphate buffer saline (PBS) containing ethanol. After 24 h, 50% of the curcumin was released from curcumin-loaded PLA fibers. These results of electrospun (e-spun) fibers exhibit the potential for biomedical application

  19. Poly(lactic acid) microencapsulated oxytetracycline: in vitro and in vivo evaluation.

    Science.gov (United States)

    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

  20. A Study of the Crystallization, Melting, and Foaming Behaviors of Polylactic Acid in Compressed CO2

    Directory of Open Access Journals (Sweden)

    Chul B. Park

    2009-12-01

    Full Text Available The crystallization and melting behaviors of linear polylactic acid (PLA treated by compressed CO2 was investigated. The isothermal crystallization test indicated that while PLA exhibited very low crystallization kinetics under atmospheric pressure, CO2 exposure significantly increased PLA’s crystallization rate; a high crystallinity of 16.5% was achieved after CO2 treatment for only 1 min at 100 °C and 6.89 MPa. One melting peak could be found in the DSC curve, and this exhibited a slight dependency on treatment times, temperatures, and pressures. PLA samples tended to foam during the gas release process, and a foaming window as a function of time and temperature was established. Based on the foaming window, crystallinity, and cell morphology, it was found that foaming clearly reduced the needed time for PLA’s crystallization equilibrium.

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

    Science.gov (United States)

    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. Hydrolytic degradation behaviour of sucrose palmitate reinforced poly(lactic acid) nanocomposites.

    Science.gov (United States)

    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

  3. Preparation and characterization of interpenetrating networks based on polyacrylates and poly(lactic acid

    Directory of Open Access Journals (Sweden)

    H. Kaczmarek

    2012-01-01

    Full Text Available Three different, multifunctional acrylic monomers were photopolymerized in a matrix of poly(lactic acid, PLA, using 2-hydroxy-2-methyl-1-phenyl-propan-1-one as a photoinitiator. The kinetics of the photopolymerization of monomers in PLA, studied with Fourier Transform Infrared Spectroscopy, has been compared to analogous processes of pure monomers under the same conditions (room temperature, air atmosphere. Additionally, poly(ethylene glycol was added to acrylate/PLA blends as plasticizer.The highly crosslinked networks obtained were characterized by FTIR and optical microscopy. The amount of insoluble gel has been estimated gravimetrically. It was found that the studied systems are characterized by very high polymerization rate, moreover, efficient grafting of polyacrylates on PLA takes place. The observed morphology indicates the heterogeneity of formed networks. The glass transition temperature of PLA in studied blends has been determined by differential scanning calorimetry.

  4. Preparation of magnetic polylactic acid microspheres and investigation of its releasing property for loading curcumin

    Energy Technology Data Exchange (ETDEWEB)

    Li Fengxia [Heilongjiang Key Laboratory of Molecular Design and Preparation of Flame Retarded Materials, College of Science, Northeast Forestry University, Harbin 150040 (China); Li Xiaoli, E-mail: lixiaoli0903@163.com [Heilongjiang Key Laboratory of Molecular Design and Preparation of Flame Retarded Materials, College of Science, Northeast Forestry University, Harbin 150040 (China); Li Bin, E-mail: libinzh62@163.com [Heilongjiang Key Laboratory of Molecular Design and Preparation of Flame Retarded Materials, College of Science, Northeast Forestry University, Harbin 150040 (China)

    2011-11-15

    In order to obtain a targeting drug carrier system, magnetic polylactic acid (PLA) microspheres loading curcumin were synthesized by the classical oil-in-water emulsion solvent-evaporation method. In the Fourier transform infrared spectra of microspheres, the present functional groups of PLA were all kept invariably. The morphology and size distribution of magnetic microspheres were observed with scanning electron microscopy and dynamic light scattering, respectively. The results showed that the microspheres were regularly spherical and the surface was smooth with a diameter of 0.55-0.75 {mu}m. Magnetic Fe{sub 3}O{sub 4} was loaded in PLA microspheres and the content of magnetic particles was 12 wt% through thermogravimetric analysis. The magnetic property of prepared microspheres was measured by vibrating sample magnetometer. The results showed that the magnetic microspheres exhibited typical superparamagnetic behavior and the saturated magnetization was 14.38 emu/g. Through analysis of differential scanning calorimetry, the curcumin was in an amorphous state in the magnetic microspheres. The drug loading, encapsulation efficiency and releasing properties of curcumin in vitro were also investigated by ultraviolet-visible spectrum analysis. The results showed that the drug loading and encapsulation efficiency were 8.0% and 24.2%, respectively. And curcumin was obviously slowly released because the cumulative release percentage of magnetic microspheres in the phosphate buffer (pH=7.4) solution was only 49.01% in 72 h, and the basic release of curcumin finished in 120 h. - Highlights: > We prepare magnetic polylactic acid microspheres loading curcumin. > The classical oil-in-water emulsion solvent-evaporation method is used. > The magnetic microspheres are regularly spherical with a diameter of 0.55-0.75 {mu}m. > They show a certain sustained release effect on in vitro drug releasing.

  5. Effects of electron beam irradiation on the structural properties of polylactic acid/polyethylene blends

    International Nuclear Information System (INIS)

    Highlights: •Electron beam irradiation on polyethylene (LDPE) and polylactic acid (PLA) blends. •Irradiated PLA/LDPE blends exhibit structural rearrangement to highly ordered structure. •Irradiated PLA/LDPE matrix extends continuity of polymer matrix with larger fibrils diameter. -- Abstract: The purpose of this research was to investigate the effects of electron beam irradiation on the properties of polylactic acid (PLA) and low density polyethylene (LDPE) blends. The PLA were compounded with 20–80% LDPE and were exposed to electron beam irradiation dosages of 20–120 kGy. The results from gel content and X-ray diffraction analyses showed that the addition of LDPE to PLA effectively increased the gel content and crystallinity. However, an increasing percentage of LDPE reduced the tensile strength and Young’s modulus of the PLA/LDPE samples due to the lower intermolecular bonding of LDPE than of PLA. Moreover, an increase in irradiation dosages gradually decreased the mechanical properties of low-LDPE PLA/LDPE. In contrast, the increasing irradiation dosage enhanced the mechanical properties of higher-LDPE PLA/LDPE. These results indicate that higher amounts of LDPE effectively react with the release of free radicals within the amorphous phase if the blends are subjected to irradiation. The higher amounts of free radicals induce the formation of three-dimensional cross-linked networks in the polymer matrix and thus increase the gel content. The irradiation-induced cross-linking in PLA/LDPE samples improves the mechanical properties and crystallinity by promoting a structural rearrangement of the polymer matrix into a highly ordered structure

  6. Effects of electron beam irradiation on the structural properties of polylactic acid/polyethylene blends

    Energy Technology Data Exchange (ETDEWEB)

    Bee, Soo-Tueen, E-mail: direct.beest@gmail.com [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Ratnam, C.T. [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Sin, Lee Tin, E-mail: direct.tinsin@gmail.com [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Tee, Tiam-Ting; Wong, Wai-Kien; Lee, Jiuun-Xiang [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Rahmat, A.R. [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2014-09-01

    Highlights: •Electron beam irradiation on polyethylene (LDPE) and polylactic acid (PLA) blends. •Irradiated PLA/LDPE blends exhibit structural rearrangement to highly ordered structure. •Irradiated PLA/LDPE matrix extends continuity of polymer matrix with larger fibrils diameter. -- Abstract: The purpose of this research was to investigate the effects of electron beam irradiation on the properties of polylactic acid (PLA) and low density polyethylene (LDPE) blends. The PLA were compounded with 20–80% LDPE and were exposed to electron beam irradiation dosages of 20–120 kGy. The results from gel content and X-ray diffraction analyses showed that the addition of LDPE to PLA effectively increased the gel content and crystallinity. However, an increasing percentage of LDPE reduced the tensile strength and Young’s modulus of the PLA/LDPE samples due to the lower intermolecular bonding of LDPE than of PLA. Moreover, an increase in irradiation dosages gradually decreased the mechanical properties of low-LDPE PLA/LDPE. In contrast, the increasing irradiation dosage enhanced the mechanical properties of higher-LDPE PLA/LDPE. These results indicate that higher amounts of LDPE effectively react with the release of free radicals within the amorphous phase if the blends are subjected to irradiation. The higher amounts of free radicals induce the formation of three-dimensional cross-linked networks in the polymer matrix and thus increase the gel content. The irradiation-induced cross-linking in PLA/LDPE samples improves the mechanical properties and crystallinity by promoting a structural rearrangement of the polymer matrix into a highly ordered structure.

  7. Preparation of magnetic polylactic acid microspheres and investigation of its releasing property for loading curcumin

    International Nuclear Information System (INIS)

    In order to obtain a targeting drug carrier system, magnetic polylactic acid (PLA) microspheres loading curcumin were synthesized by the classical oil-in-water emulsion solvent-evaporation method. In the Fourier transform infrared spectra of microspheres, the present functional groups of PLA were all kept invariably. The morphology and size distribution of magnetic microspheres were observed with scanning electron microscopy and dynamic light scattering, respectively. The results showed that the microspheres were regularly spherical and the surface was smooth with a diameter of 0.55-0.75 μm. Magnetic Fe3O4 was loaded in PLA microspheres and the content of magnetic particles was 12 wt% through thermogravimetric analysis. The magnetic property of prepared microspheres was measured by vibrating sample magnetometer. The results showed that the magnetic microspheres exhibited typical superparamagnetic behavior and the saturated magnetization was 14.38 emu/g. Through analysis of differential scanning calorimetry, the curcumin was in an amorphous state in the magnetic microspheres. The drug loading, encapsulation efficiency and releasing properties of curcumin in vitro were also investigated by ultraviolet-visible spectrum analysis. The results showed that the drug loading and encapsulation efficiency were 8.0% and 24.2%, respectively. And curcumin was obviously slowly released because the cumulative release percentage of magnetic microspheres in the phosphate buffer (pH=7.4) solution was only 49.01% in 72 h, and the basic release of curcumin finished in 120 h. - Highlights: → We prepare magnetic polylactic acid microspheres loading curcumin. → The classical oil-in-water emulsion solvent-evaporation method is used. → The magnetic microspheres are regularly spherical with a diameter of 0.55-0.75 μm. → They show a certain sustained release effect on in vitro drug releasing.

  8. Biodegradation of clofibric acid and identification of its metabolites

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); ESTS-IPS, Escola Superior de Tecnologia de Setubal do Instituto Politecnico de Setubal, Rua Vale de Chaves, Campus do IPS, Estefanilha, 2910-761 Setubal (Portugal); Oehmen, A. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Carvalho, G. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Instituto de Biologia Experimental e Tecnologica (IBET), Av. da Republica (EAN), 2784-505 Oeiras (Portugal); Noronha, J.P. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Reis, M.A.M., E-mail: amr@fct.unl.pt [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2012-11-30

    Graphical abstract: Metabolites produced during clofibric acid biodegradation. Highlights: Black-Right-Pointing-Pointer Clofibric acid is biodegradable. Black-Right-Pointing-Pointer Mainly heterotrophic bacteria degraded the clofibric acid. Black-Right-Pointing-Pointer Metabolites of clofibric acid biodegradation were identified. Black-Right-Pointing-Pointer The metabolic pathway of clofibric acid biodegradation is proposed. - Abstract: Clofibric acid (CLF) is the pharmaceutically active metabolite of lipid regulators clofibrate, etofibrate and etofyllinclofibrate, and it is considered both environmentally persistent and refractory. This work studied the biotransformation of CLF in aerobic sequencing batch reactors (SBRs) with mixed microbial cultures, monitoring the efficiency of biotransformation of CLF and the production of metabolites. The maximum removal achieved was 51% biodegradation (initial CLF concentration = 2 mg L{sup -1}), where adsorption and abiotic removal mechanisms were shown to be negligible, showing that CLF is indeed biodegradable. Tests showed that the observed CLF biodegradation was mainly carried out by heterotrophic bacteria. Three main metabolites were identified, including {alpha}-hydroxyisobutyric acid, lactic acid and 4-chlorophenol. The latter is known to exhibit higher toxicity than the parent compound, but it did not accumulate in the SBRs. {alpha}-Hydroxyisobutyric acid and lactic acid accumulated for a period, where nitrite accumulation may have been responsible for inhibiting their degradation. A metabolic pathway for the biodegradation of CLF is proposed in this study.

  9. Effects of a tetracycline blended polylactic and polyglycolic acid membrane on the healing of one-wall intrabony defects in beagle dogs

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the regenerative effects of a tetracycline blended polylactic and polyglycolic acid (TC-PLGA) and non-blended polylactic and polyglycolic acid (PLGA) barrier membrane on one-wall intrabony defects in beagle dogs. It can be concluded that when used for guided tissue regeneration TC-PLGA membranes show a beneficial effect on one-wall intrabony defects in beagle dogs

  10. Effects of a tetracycline blended polylactic and polyglycolic acid membrane on the healing of one-wall intrabony defects in beagle dogs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Il-Young [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Jung, Ui-Won [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chang-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Lee, Yong-Keun [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of); Cho, Kyoo-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Chai, Jung-Kiu [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chong-Kwan [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of)

    2007-09-15

    The purpose of this study was to evaluate the regenerative effects of a tetracycline blended polylactic and polyglycolic acid (TC-PLGA) and non-blended polylactic and polyglycolic acid (PLGA) barrier membrane on one-wall intrabony defects in beagle dogs. It can be concluded that when used for guided tissue regeneration TC-PLGA membranes show a beneficial effect on one-wall intrabony defects in beagle dogs.

  11. Antibacterial Efficiency of Hydroxyapatite Biomaterials with Biodegradable Polylactic Acid and Polycaprolactone Polymers Saturated with Antibiotics / Bionoārdāmu Polimēru Saturošu Un Ar Antibiotiskajām Vielām Piesūcinātu Biomateriālu Antibakteriālās Efektivitātes Noteikšana

    Directory of Open Access Journals (Sweden)

    Kroiča Juta

    2016-08-01

    Full Text Available Infections continue to spread in all fields of medicine, and especially in the field of implant biomaterial surgery, and not only during the surgery, but also after surgery. Reducing the adhesion of bacteria could decrease the possibility of biomaterial-associated infections. Bacterial adhesion could be reduced by local antibiotic release from the biomaterial. In this in vitro study, hydroxyapatite biomaterials with antibiotics and biodegradable polymers were tested for their ability to reduce bacteria adhesion and biofilm development. This study examined the antibacterial efficiency of hydroxyapatite biomaterials with antibiotics and biodegradable polymers against Staphylococcus epidermidis and Pseudomonas aeruginosa. The study found that hydroxyapatite biomaterials with antibiotics and biodegradable polymers show longer antibacterial properties than hydroxyapatite biomaterials with antibiotics against both bacterial cultures. Therefore, the results of this study demonstrated that biomaterials that are coated with biodegradable polymers release antibiotics from biomaterial samples for a longer period of time and may be useful for reducing bacterial adhesion on orthopedic implants.

  12. Preparation and Characterization of Films Extruded of Polyethylene/Chitosan Modified with Poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Jesús Manuel Quiroz-Castillo

    2014-12-01

    Full Text Available The use of mixtures of synthetic and natural polymers is a potential option to reduce the pollution by plastic waste. In this work, the method for the chemical modification of chitosan with poly(lactic acid was developed; then, the preparation of films of blends of polyethylene and chitosan-poly(lactic acid produced by an extrusion method using polyethylene-graft maleic anhydride as a compatibilizer. It was possible to obtain films with a maximum content of 20 wt% and 30 wt%, chitosan, with and without compatibilizer, respectively. Scanning electron microscope (SEM analysis showed a homogeneous surface on all films. The addition of the compatibilizer had a significant effect on the mechanical properties of the films, such as an increase in Young’s modulus and a decrease in the elongation at break; additionally, the compatibilizer promotes thermal degradation in a single step and gives the film a slight increase in thermal resistance. These results are attributed to an improved interaction in the interface of polyethylene and chitosan-poly(lactic acid, promoted by the compatibilizer.

  13. A New Esterase from Thermobifida halotolerans Hydrolyses Polyethylene Terephthalate (PET and Polylactic Acid (PLA

    Directory of Open Access Journals (Sweden)

    Georg Steinkellner

    2012-02-01

    Full Text Available A new esterase from Thermobifida halotolerans (Thh_Est was cloned and expressed in E. coli and investigated for surface hydrolysis of polylactic acid (PLA and polyethylene terephthalate (PET. Thh_Est is a member of the serine hydrolases superfamily containing the -GxSxG- motif with 85–87% homology to an esterase from T. alba, to an acetylxylan esterase from T. fusca and to various Thermobifida cutinases. Thh_Est hydrolyzed the PET model substrate bis(benzoyloxyethylterephthalate and PET releasing terephthalic acid and mono-(2-hydroxyethyl terephthalate in comparable amounts (19.8 and 21.5 mmol/mol of enzyme while no higher oligomers like bis-(2-hydroxyethyl terephthalate were detected. Similarly, PLA was hydrolyzed as indicated by the release of lactic acid. Enzymatic surface hydrolysis of PET and PLA led to a strong hydrophilicity increase, as quantified with a WCA decrease from 90.8° and 75.5° to 50.4° and to a complete spread of the water drop on the surface, respectively.

  14. SYNTHESIS AND PROPERTIES OF HIGH MOLECULAR WEIGHT POLY(LACTIC ACID) AND ITS RESULTANT FIBERS

    Institute of Scientific and Technical Information of China (English)

    Wang-xi Zhang; Yan-zhi Wang

    2008-01-01

    Direct melt/solid polycondensation of lactic acid (LA) was carried out to obtain high molecular weight poly(lactic acid) (PLA) by a process using various catalysts in the first-step melt polycondensation, and followed solid polycondensation by using p-toulenesulfonic acid monohydrate (TSA) as the catalyst in the second step. Effects of various catalysts and reaction temperature on the molecular weight and crystallinity of resulting PLA polymers were examined. It was shown that SnCl2·2H2O/TSA, SnCl2·2H2O/succinic anhydride, and SnCl2·2H2O/maleic anhydride binary catalysts should be effective binary catalysts to obtain high molecular weight PLA of more than 1.2 × 105. A conventional melt spinning method was used to spin PLA fibers, which displayed tensile strength of (382.76±1.41) MPa and tensile modulus of (4.36±0.07) GPa.

  15. Transparent bionanocomposites with improved properties prepared from acetylated bacterial cellulose and poly(lactic acid) through a simple approach

    OpenAIRE

    Tomé, Liliana C.; Ricardo J. B. Pinto; Trovatti, Eliane; Freire, Carmen S. R.; Silvestre, Armando J. D.; Neto, Carlos Pascoal; Gandini, Alessandro

    2011-01-01

    The preparation and characterization of biocomposite materials with improved properties based on poly(lactic acid) (PLA) and bacterial cellulose, and, for comparative purposes, vegetal cellulose fibers, both in their pristine form or after acetylation, is reported. The composite materials were obtained through the simple and green mechanical compounding of a PLA matrix and bacterial cellulose nanofibrils (or vegetable fibers), and were characterized by TGA, DSC, tensile assays, DMA, SEM and w...

  16. Characterization of Active Packaging Films Made from Poly(Lactic Acid)/Poly(Trimethylene Carbonate) Incorporated with Oregano Essential Oil

    OpenAIRE

    Dong Liu; Hongli Li; Lin Jiang; Yongming Chuan; Minglong Yuan; Haiyun Chen

    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. Differ...

  17. Combined Effect of Poly(hydroxybutyrate) and Plasticizers on Polylactic acid Properties for Film Intended for Food Packaging

    OpenAIRE

    ARRIETA, Marina Patricia; Samper, María D.; López, Juan; Jiménez, Alfonso

    2014-01-01

    Poly(lactic acid) PLA, and poly(hydroxybutyrate) PHB, blends were processed as films and characterized for their use in food packaging. PLA was blended with PHB to enhance the crystallinity. Therefore, PHB addition strongly increased oxygen barrier while decreased the wettability. Two different environmentally-friendly plasticizers, poly(ethylene glycol) (PEG) and acetyl(tributyl citrate) (ATBC), were added to these blends to increase their processing performance, while improving their ductil...

  18. Development and characterization of a coronary polylactic acid stent prototype generated by selective laser melting.

    Science.gov (United States)

    Flege, Christian; Vogt, Felix; Höges, Simon; Jauer, Lucas; Borinski, Mauricio; Schulte, Vera A; Hoffmann, Rainer; Poprawe, Reinhart; Meiners, Wilhelm; Jobmann, Monika; Wissenbach, Konrad; Blindt, Rüdiger

    2013-01-01

    In-stent restenosis is still an important issue and stent thrombosis is an unresolved risk after coronary intervention. Biodegradable stents would provide initial scaffolding of the stenosed segment and disappear subsequently. The additive manufacturing technology Selective Laser Melting (SLM) enables rapid, parallel, and raw material saving generation of complex 3- dimensional structures with extensive geometric freedom and is currently in use in orthopedic or dental applications. Here, SLM process parameters were adapted for poly-L-lactid acid (PLLA) and PLLA-co-poly-ε-caprolactone (PCL) powders to generate degradable coronary stent prototypes. Biocompatibility of both polymers was evidenced by assessment of cell morphology and of metabolic and adhesive activity at direct and indirect contact with human coronary artery smooth muscle cells, umbilical vein endothelial cells, and endothelial progenitor cells. γ-sterilization was demonstrated to guarantee safety of SLM-processed parts. From PLLA and PCL, stent prototypes were successfully generated and post-processing by spray- and dip-coating proved to thoroughly smoothen stent surfaces. In conclusion, for the first time, biodegradable polymers and the SLM technique were combined for the manufacturing of customized biodegradable coronary artery stent prototypes. SLM is advocated for the development of biodegradable coronary PLLA and PCL stents, potentially optimized for future bifurcation applications. PMID:23053808

  19. 聚乳酸合成技术研究进展%Research progress in polylactic acid synthesis

    Institute of Scientific and Technical Information of China (English)

    胡建军

    2012-01-01

    Polylactic acid(PLA) has attracted great attention because of its biodegradability,excellent functional performance and wide application area.Two kinds of chemical synthetic methods of PLA,ring-opening polymerization of lactide(ROPL) and condensation polymerization of lactic acid(CPLA),are reviewed.High molecular weight PLA can be obtained with simple equipment by ROPL route,whereas high cost,complicated technique and long procedure are associated.Alternatively,CPLA route is favorable on the basis of abundant source of cheap raw material,high monomer conversion rate and simple synthetic technique.Meanwhile,the process of intermediate purification is not needed,which leads to low production cost.However,high molecular weight polymer cannot be obtained by this route.Currently,the important research area of PLA includes developing new synthetic technology to further reduce the manufacturing cost.It is imperative to make a breakthrough to find a simple and easy way to prepare PLA with high molecular weight.%聚乳酸因可生物降解、性能优异、应用广泛而深受青睐。本文介绍了2种主要化学合成聚乳酸的方法:丙交酯开环聚合法和乳酸直接缩聚法。分析了这2种方法的优势和缺陷:丙交酯开环聚合法设备简单,可得到大分子量的聚乳酸,缺点是成本较高,整个工艺复杂,路线长;乳酸直接缩聚法原料乳酸来源充足,价格便宜,单体转化率较高,工艺简单,不需要经过中间体的纯化,因而成本较低,缺陷是较难得到高分子量的聚合物。文中指出积极开展聚乳酸的合成工艺研发、进一步降低生产成本是当前聚乳酸研究的重要课题,重点在于简单易行的高分子量聚乳酸合成工艺的突破。

  20. Purified terephthalic acid wastewater biodegradation and toxicity

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-xiang; LUO Xiang; GU Ji-dong; WAN Yu-qiu; CHENG Shu-pei; SUN Shi-lei; ZHU Cheng-jun; LI Wei-xin; ZHANG Xiao-chun; WANG Gui-lin; LU Jian-hua

    2005-01-01

    The biodegradation and toxicity of the purified terephthalic acid(PTA) processing wastewater was researched at NJYZ pilot with the fusant strain Fhhh in the carrier activated sludge process(CASP). Sludge loading rate(SLR) for Fhhh to COD of the wastewater was 1.09 d-1 and to PTA in the wastewater was 0.29 d-1. The results of bioassay at the pilot and calculation with software Ebis3 showed that the 48h-LC50 (median lethal concentration) to Daphnia magna for the PTA concentration in the wastewater was only 1/10 of that for the chemical PTA. There were 5 kinds of benzoate pollutants and their toxicities existing in the wastewater at least. The toxicity parameter value of the pure chemical PTA cannot be used to predicate the PTA wastewater toxicity. The toxicity of the NJYZ PTA wastewater will be discussed in detail in this paper.

  1. The Recent Advances in Development of Lactic Acid and Polylactic Acid%乳酸和聚乳酸的最新进展

    Institute of Scientific and Technical Information of China (English)

    刘伟雄

    2001-01-01

    The recent advances in the fermentation production of lactic acid with different microorganisms, recovery and detection of lactic acid, and the production of polylactic acid are reviewed in this paper.%综述了不同的产酸菌发酵生产乳酸、乳酸的提取与检测以及聚乳酸的生产等方面的最新进展。

  2. Processing and characterization of poly(lactic acid based bioactive composites for biomedical scaffold application

    Directory of Open Access Journals (Sweden)

    J. Goswami

    2013-09-01

    Full Text Available The current study focuses on three-components material systems (poly(lactic acid (PLA, poly(ε-caprolactone (PCL and wollastonite (W in view of possible application a biomedical scaffold constructs. Melt extruded PLA/PCL/W composites (PLCL15, PLCLW1, PLCLW4, PLCLW8 containing 0, 1, 4, 8 phr filler respectively are batch foamed using compressed CO2 and the porous foams are studied for in vitro biocompatibility by seeding osteoblast cells. SEM images of the unfoamed polymers show immiscibility in all compositions. Materials have been tested under compressive load using dry and wet conditions (using phosphate buffered saline at pH 7.4 for in vitro study. Contact angle measurement shows enhanced hydrophilicity in the composites changing from 80° in PLCL15 to 72° in PLCLW8. The foams are found to be microcellular (5–8 µm in morphology showing quite uniform pore distribution in the composites. The prepared foams, when studied as scaffold constructs, show osteoblast cell attachment and proliferation over the incubation period of 7 days. As expected, PLCLW8 containing highest amount of CaSiO3 supported maximum cell growth on its surface as visible from MTT assay data and SEM scans.

  3. Interactions, structure and properties in poly(lactic acid/thermoplastic polymer blends

    Directory of Open Access Journals (Sweden)

    B. Imre

    2014-01-01

    Full Text Available Blends were prepared from poly(lactic acid (PLA and three thermoplastics, polystyrene (PS, polycarbonate (PC and poly(methyl methacrylate (PMMA. Rheological and mechanical properties, structure and component interactions were determined by various methods. The results showed that the structure and properties of the blends cover a relatively wide range. All three blends have heterogeneous structure, but the size of the dispersed particles differs by an order of magnitude indicating dissimilar interactions for the corresponding pairs. Properties change accordingly, the blend containing the smallest dispersed particles has the largest tensile strength, while PLA/PS blends with the coarsest structure have the smallest. The latter blends are also very brittle. Component interactions were estimated by four different methods, the determination of the size of the dispersed particles, the calculation of the Flory-Huggins interaction parameter from solvent absorption, from solubility parameters, and by the quantitative evaluation of the composition dependence of tensile strength. All approaches led to the same result indicating strong interaction for the PLA/PMMA pair and weak for PLA and PS. A general correlation was established between interactions and the mechanical properties of the blends.

  4. Enhancement of Mechanical and Thermal Properties of Polylactic Acid/Polycaprolactone Blends by Hydrophilic Nanoclay

    Directory of Open Access Journals (Sweden)

    Chern Chiet Eng

    2013-01-01

    Full Text Available The effects of hydrophilic nanoclay, Nanomer PGV, on mechanical properties of Polylactic Acid (PLA/Polycaprolactone (PCL blends were investigated and compared with hydrophobic clay, Montmorillonite K10. The PLA/PCL/clay composites were prepared by melt intercalation technique and the composites were characterized by X-ray Diffraction (XRD, Fourier Transform Infrared Spectroscopy (FTIR, Thermogravimetric Analysis (TGA, Dynamic Mechanical Analysis (DMA, Scanning Electron Microscopy (SEM, and Transmission Electron Microscopy (TEM. FTIR spectra indicated that formation of hydrogen bond between hydrophilic clay with the matrix. XRD results show that shifting of basal spacing when clay incorporated into polymer matrix. TEM micrographs reveal the formation of agglomerate in the composites. Based on mechanical properties results, addition of clay Nanomer PGV significantly enhances the flexibility of PLA/PCL blends about 136.26%. TGA showed that the presence of clay improve thermal stability of blends. DMA show the addition of clay increase storage modulus and the presence of clay Nanomer PGV slightly shift two Tg of blends become closer suggest that the presence of clay slightly compatibilizer the PLA/PCL blends. SEM micrographs revealed that presence of Nanomer PGV in blends influence the miscibility of the blends. The PLA/PCL blends become more homogeneous and consist of single phase morphology.

  5. Development and characterization of sugar palm starch and poly(lactic acid) bilayer films.

    Science.gov (United States)

    Sanyang, M L; Sapuan, S M; Jawaid, M; Ishak, M R; Sahari, J

    2016-08-01

    The development and characterization of environmentally friendly bilayer films from sugar palm starch (SPS) and poly(lactic acid) (PLA) were conducted in this study. The SPS-PLA bilayer films and their individual components were characterized for their physical, mechanical, thermal and water barrier properties. Addition of 50% PLA layer onto 50% SPS layer (SPS50-PLA50) increased the tensile strength of neat SPS film from 7.74 to 13.65MPa but reduced their elongation at break from 46.66 to 15.53%. The incorporation of PLA layer significantly reduced the water vapor permeability as well as the water uptake and solubility of bilayer films which was attributed to the hydrophobic characteristic of the PLA layer. Furthermore, scanning electron microscopy (SEM) image of SPS50-PLA50 revealed lack of strong interfacial adhesion between the SPS and PLA. Overall, the incorporation of PLA layer onto SPS films enhances the suitability of SPS based films for food packaging. PMID:27112848

  6. Neuron attachment properties of carbon negative-ion implanted bioabsorbable polymer of poly-lactic acid

    International Nuclear Information System (INIS)

    Modification of a bioabsorbable polymer of poly-lactic acid (PLA) by negative carbon ion implantation was investigated with resect to radiation effects on surface physical properties and nerve-cell attachment properties. Carbon negative ions were implanted to PLA at energy of 5-30 keV with a dose of 1014-1016 ions/cm2. Most C-implanted PLA samples showed contact angles near 80 deg. and almost same as that of unimplanted PLA, although a few samples at 5 keV and less 3x1014 ions/cm2 had contact angles larger than 90 deg. The attachment properties of nerve cells of PC-12h (rat adrenal phechromocytoma) in vitro were studied. PC-12h cells attached on the unimplanted region in C-implanted PLA samples at 5 and 10 keV. On the contrary, the nerve cells attached on only implanted region for the C-implanted PLA sample at 30 keV and 1x1015 ions/cm2

  7. Mechanical Properties of Poly(lactic acid Sheet Reinforced with Microfibrillated Cellulose from Corn Cobs

    Directory of Open Access Journals (Sweden)

    Deejam Prapatsorn

    2015-01-01

    Full Text Available In this study, cellulose was extracted from corn cobs by successive hot NaOH solution and followed by H2O2 bleaching. XRD pattern show characteristic peak of Cellulose I. Microfibrillated cellulose (MFC was successfully prepared by dissolving the extracted cellulose in NaOH/urea solution, shearing in a homogenizer and finally by freezing and thawing. To improve strength of MFC, MFC was physically crosslinked using PVA by freezing and thawing. The crosslinked MFC/PVA was added to poly(lactic acid (PLA to improve its mechanical properties. The non-crosslinked MFC/PVA was also prepared by only stirring the solution without freezing and thawing. MFC/PVA reinforced PLA films with various ratios of PLA and MFC/PVA at100:0, 99:1, 97:3 and 95:5were prepared through a solution casting method. Tensile strength and elongation at breakof PLA films increased with the addition of physically crosslinked MFC/PVA at 1%wt, whereas, the addition of non-crosslinked MFC/PVA decreased elongation at break. Crosslinking of MFC/PVA can improve tensile strength of PLA.It can render better tensile strength than that of non-crosslinked MFC/PVA. However, when MFC/PVA contents increase, tensile strength of PLA fims reinforced with non-crosslinked and crosslinked MFC/PVA decreased. Morphology of fracture surfaces reveals good dispersion and adhesion between 1% crosslinked MFC/PVA and PLA matrix.

  8. Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Xingxun Liu

    2014-01-01

    Full Text Available Addition of filler to polylactic acid (PLA may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC, scanning electron microscope (SEM, instron tensile tester, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, and dynamic mechanical analysis (DMA. It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

  9. Novel silver-based nanoclay as an antimicrobial in polylactic acid food packaging coatings.

    Science.gov (United States)

    Busolo, Maria A; Fernandez, Patricia; Ocio, Maria J; Lagaron, Jose M

    2010-11-01

    This paper presents a comprehensive performance study of polylactic acid (PLA) biocomposites, obtained by solvent casting, containing a novel silver-based antimicrobial layered silicate additive for use in active food packaging applications. The silver-based nanoclay showed strong antimicrobial activity against Gram-negative Salmonella spp. Despite the fact that no exfoliation of the silver-based nanoclay in PLA was observed, as suggested by transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) experiments, the additive dispersed nicely throughout the PLA matrix to a nanoscale, yielding nanobiocomposites. The films were highly transparent with enhanced water barrier and strong biocidal properties. Silver migration from the films to a slightly acidified water medium, considered an aggressive food simulant, was measured by stripping voltammetry. Silver migration accelerated after 6 days of exposure. Nevertheless, the study suggests that migration levels of silver, within the specific migration levels referenced by the European Food Safety Agency (EFSA), exhibit antimicrobial activity, supporting the potential application of this biocidal additive in active food-packaging applications to improve food quality and safety. PMID:20711905

  10. Electrospun polylactic acid and polyvinyl alcohol fibers as efficient and stable nanomaterials for immobilization of lipases.

    Science.gov (United States)

    Sóti, Péter Lajos; Weiser, Diana; Vigh, Tamás; Nagy, Zsombor Kristóf; Poppe, László; Marosi, György

    2016-03-01

    Electrospinning was applied to create easy-to-handle and high-surface-area membranes from continuous nanofibers of polyvinyl alcohol (PVA) or polylactic acid (PLA). Lipase PS from Burkholderia cepacia and Lipase B from Candida antarctica (CaLB) could be immobilized effectively by adsorption onto the fibrous material as well as by entrapment within the electrospun nanofibers. The biocatalytic performance of the resulting membrane biocatalysts was evaluated in the kinetic resolution of racemic 1-phenylethanol (rac-1) and 1-phenylethyl acetate (rac-2). Fine dispersion of the enzymes in the polymer matrix and large surface area of the nanofibers resulted in an enormous increase in the activity of the membrane biocatalyst compared to the non-immobilized crude powder forms of the lipases. PLA as fiber-forming polymer for lipase immobilization performed better than PVA in all aspects. Recycling studies with the various forms of electrospun membrane biocatalysts in ten cycles of the acylation and hydrolysis reactions indicated excellent stability of this forms of immobilized lipases. PLA-entrapped lipases could preserve lipase activity and enantiomer selectivity much better than the PVA-entrapped forms. The electrospun membrane forms of CaLB showed high mechanical stability in the repeated acylations and hydrolyses than commercial forms of CaLB immobilized on polyacrylamide beads (Novozyme 435 and IMMCALB-T2-150). PMID:26724947

  11. Physical changes of poly(lactic acid) induced by water sorption

    Science.gov (United States)

    Pantani, Roberto; De Santis, Felice

    2015-12-01

    One of the main limits to the use of Poly(Lactic Acid), PLA, is its extreme sensitivity to moisture. The objective of this work is to study the physical changes induced by water sorption on a commercial PLA grade. To this goal, samples of PLA having thickness of about 400 µm, obtained by compression molding, were put into contact with water at 58 °C. The samples were partially immersed in water in a closed and mixed vessel, so that the lower part was in contact with liquid water whereas the upper part was in contact with air with a relative humidity of 100%. The opacity of the samples, their crystallinity degree, their density and molecular weight were monitored during time. It was found that the samples became white and opaque after a few hours, crystallinity reached an equilibrium value after about 48 h. Density was found to decrease with time, thus suggesting that the whitening was due to crazing. Surprisingly, it was found that the mentioned phenomena are more evident for the samples immersed in water than for those surrounded by a 100% RH atmosphere.

  12. Barrier Properties of Polylactic Acid in Cellulose Based Packages Using Montmorillonite as Filler

    Directory of Open Access Journals (Sweden)

    Daniela Sánchez Aldana

    2014-09-01

    Full Text Available Polylactic acid (PLA and montmorillonite (CB as filler were studied as coatings for cellulose based packages. Amorphous (AM and semi crystalline (SC PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was three concentrations and coating was performed by casting. Contact angle (CA, water vapor (WVP and grease permeabilities were measured for each resultant package and were compared to commercial materials (Glassine Paper, Grease Proof Papers 1 and 2 produced commercially. Significant differences were found and the main factors were the type and concentration of PLA. The best values were: for grease penetration, +1800 s; WVP from 161.36 to 237.8 g·µm·kPa−1·m−2·d−1 and CA from 69° to 73° for PLA–AM 0.5% and CB variable. These parameters are comparable to commercial packages used in the food industry. DSC revealed three different thermal events for PLA–SC and just Tg for PLA–AM. Crystallinity was also verified, obtaining a ΔHcrys of 3.7 J·g−1 for PLA–SC and 14 J·g−1 for PLA–SC–BC, evidencing clay interaction as a crystal nucleating agent. Differences found were explained on terms of the properties measured, where structural and chemical arrays of the coatings play a fundamental role for the barrier properties.

  13. Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

    Science.gov (United States)

    Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

    2016-02-10

    Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue. PMID:26756809

  14. Analysis of Gas Permeability Characteristics of Poly(Lactic Acid/Poly(Butylene Succinate Nanocomposites

    Directory of Open Access Journals (Sweden)

    Amita Bhatia

    2012-01-01

    Full Text Available Gas permeability and morphological properties of nanocomposites prepared by the mixing of poly(lactic acid (PLA, poly(butylene succinate (PBS, and clay was investigated. While the composition of PLA and PBS polymers was fixed as 80% and 20% by weight, respectively, for all the nanocomposites, clay contents varied from 1 to 10 wt%. From the morphological studies using both wide angle X-ray diffraction and transmission electron microscopy, the nanocomposite having 1 wt% of clay was considered to have a mixed morphology of intercalated and delaminated structure, while some clusters or agglomerated particles were detected for nanocomposites having 3 and more than 3 wt% of clay content. However, the average particle size of the dispersed PBS phase was reduced significantly from 7 μm to 30–40 nm with the addition of clay in the blend. The oxygen barrier property was improved significantly as compared to the water vapor. A model based on gas barrier property was used for the validation of the oxygen relative permeabilities of PLA/PBS/clay nanocomposites. PLA/PBS/clay nanocomposites validated the Bharadwaj model up to 3 wt% of clay contents only, while for nanocomposites of higher clay contents the Bharadwaj model was invalid due to the clusters and agglomerates formed.

  15. Preparation of Lung-Targeting, Emodin-Loaded Polylactic Acid Microspheres and Their Properties

    Directory of Open Access Journals (Sweden)

    Xiaohong Chen

    2014-04-01

    Full Text Available Emodin (1,3,8-trihydroxy-6-methylanthraquinone has been identified to have the potential to improve lung fibrosis and lung cancer. To avoid the liver and kidney toxicities and the fast metabolism of emodin, emodin-loaded polylactic acid microspheres (ED-PLA-MS were prepared and their characteristics were studied. ED-PLA-MS were prepared by the organic phase dispersion-solvent diffusion method. By applying an orthogonal design, our results indicated that the optimal formulation was 12 mg/mL PLA, 0.5% gelatin, and an organic phase:glycerol ratio of 1:20. Using the optimal experimental conditions, the drug loading and encapsulation efficiencies were (19.0 ± 1.8% and (62.2 ± 2.6%, respectively. The average particle size was 9.7 ± 0.7 μm. In vitro studies indicated that the ED-PLA-MS demonstrated a well-sustained release efficacy. The microspheres delivered emodin, primarily to the lungs of mice, upon intravenous injection. It was also detected by microscopy that partial lung inflammation was observed in lung tissues and no pathological changes were found in other tissues of the ED-PLA-MS-treated animals. These results suggested that ED-PLA-MS are of potential value in treating lung diseases in animals.

  16. Epoxidized Vegetable Oils Plasticized Poly(lactic acid Biocomposites: Mechanical, Thermal and Morphology Properties

    Directory of Open Access Journals (Sweden)

    Buong Woei Chieng

    2014-10-01

    Full Text Available Plasticized poly(lactic acid PLA with epoxidized vegetable oils (EVO were prepared using a melt blending method to improve the ductility of PLA. The plasticization of the PLA with EVO lowers the Tg as well as cold-crystallization temperature. The tensile properties demonstrated that the addition of EVO to PLA led to an increase of elongation at break, but a decrease of tensile modulus. Plasticized PLA showed improvement in the elongation at break by 2058% and 4060% with the addition of 5 wt % epoxidized palm oil (EPO and mixture of epoxidized palm oil and soybean oil (EPSO, respectively. An increase in the tensile strength was also observed in the plasticized PLA with 1 wt % EPO and EPSO. The use of EVO increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. The SEM micrograph of the plasticized PLA showed good compatible morphologies without voids resulting from good interfacial adhesion between PLA and EVO. Based on the results of this study, EVO may be used as an environmentally friendly plasticizer that can improve the overall properties of PLA.

  17. Crystalline structure of annealed polylactic acid and its relation to processing

    Directory of Open Access Journals (Sweden)

    2010-10-01

    Full Text Available This paper focuses on the crystalline structure of injection moulding grade poly(lactic acid (PLA and the effect of crystalline structure on the processing. The research is induced by the significant differences in crystallinity of the pure PLA resin, and the injection moulded product, and thus the reprocessing of PLA products. 2 mm thick PLA sheets were injection moulded and re-crystallized in a conventional oven at 60–140°C, for 10–60 minutes to achieve various crystalline contents. The properties of these sheets were investigated by dynamic mechanical analysis (DMA, differential scanning calorimetry (DSC, and wide angle X-ray diffraction (WAXD. In a processing plant the rejected parts are recycled and reused as raw material for further cycles, accordingly the various crystalline content PLA products were reprocessed as a resin, to investigate the processing itself. When PLA products are reprocessed, due to the adherent feature of amorphous PLA processing difficulties may occur. This adherent effect of the amorphous PLA was investigated and characterized.

  18. Biodegradation of flax fiber reinforced poly lactic acid

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available Woven and nonwoven flax fiber reinforced poly lactic acid (PLA biocomposites were prepared with amphiphilic additives as accelerator for biodegradation. The prepared composites were buried in farmland soil for biodegradability studies. Loss in weight of the biodegraded composite samples was determined at different time intervals. The surface morphology of the biodegraded composites was studied with scanning electron microscope (SEM. Results indicated that in presence of mandelic acid, the composites showed accelerated biodegradation with 20–25% loss in weight after 50–60 days. On the other hand, in presence of dicumyl peroxide (as additive, biodegradation of the composites was relatively slow as confirmed by only 5–10% loss in weight even after 80–90 days. This was further confirmed by surface morphology of the biodegraded composites. We have attempted to show that depending on the end uses, we can add different amphiphilic additives for delayed or accelerated biodegradability. This work gives us the idea of biodegradation of materials from natural fiber reinforced PLA composites when discarded carelessly in the environment instead of proper waste disposal site.

  19. Solvent-free preparation of polylactic acid fibers by melt electrospinning using umbrella-like spray head and alleviation of problematic thermal degradation

    Directory of Open Access Journals (Sweden)

    Liu Yong

    2012-01-01

    Full Text Available Melt electrospinning is an even simpler and safer method compared with the solution electrospinning in the production of ultra-fine fibers. Polylactic acid (PLA is a biodegradable and resorbable aliphatic ester that has received significant attention in recent years. PLA is easily degradable at high temperature in the process of melt electrospinning. High efficient fibers were made using our designed umbrella-like spray head spinning facility in this work. To find how to alleviate the problematic degradation and what factors could be relevant to degradation, temperature, relative molecular mass, Differential Scanning Calorimeter and X-ray Diffraction patterns before and after spinning were investigated and compared with each other. Results showed that fibers were facile shorten and fractured when spun at 245°C while the relative molecular mass of PLA fibers decreased markedly as compared with that spun at 210°C. To hinder the degradation, couple of experimental efforts were implemented with adding antioxidants, raising spinning voltage, lowering temperature, and reducing residence time. After such efforts, it was observed that the relative molecular mass of the PLA fibers was higher than those without inputting any efforts. The effect of antioxidant 1010 was found the most promising on the alleviation of PLA problematic thermal degradation.

  20. The effect of maleinized linseed oil (MLO) on mechanical performance of poly(lactic acid)-thermoplastic starch (PLA-TPS) blends.

    Science.gov (United States)

    Ferri, J M; Garcia-Garcia, D; Sánchez-Nacher, L; Fenollar, O; Balart, R

    2016-08-20

    In this work, poly(lactic acid), PLA and thermoplastic starch, TPS blends (with a fixed content of 30wt.% TPS) were prepared by melt extrusion process to increase the low ductile properties of PLA. The TPS used contains an aliphatic/aromatic biodegradable polyester (AAPE) that provides good resistance to aging and moisture. This blend provides slightly improved ductile properties with an increase in elongation at break of 21.5% but phase separation is observed due to the lack of strong interactions between the two polymers. Small amounts of maleinized linseed oil (MLO) can positively contribute to improve the ductile properties of these blends by a combined plasticizing-compatibilizing effect. The elongation at break increases over 160% with the only addition of 6phr MLO. One of the evidence of the plasticizing-compatibilizing effect provided by MLO is the change in the glass transition temperature (Tg) with a decrease of about 10°C. Field emission scanning electron microscopy (FESEM) of PLA-TPS blends with varying amounts of maleinized linseed oil also suggests an increase in compatibility. PMID:27178909

  1. Effect of twist-orientation on mechanical properties of self-reinforced poly(lactic acid) screws in simulated body environment

    Science.gov (United States)

    Sakaguchi, Masato; Kobayashi, Satoshi; composite engineering lab Team

    Poly(lactic acid) (PLA) attracts much attention as a typical biodegradable polymer, and has been applied as a bone fixation device. As one of the methods to improve mechanical properties of PLA bone fixation device, orientations of molecular chains have been investigated. However, conventional uniaxial drawing could not improve mechanical properties along the other loading direction than the drawing direction, such as torsion. In this study, screw is treated as a bone fixation device. In order to improve torsional strength of a bioabsorbable PLA screw, twist-orientation method has been developed. PLA screw is prepared through a series of routes including extrusion molding, extrusion drawing, twist-orientation and forging. This screw was immersed in the phosphate buffer solution for 0, 8, 16 and 24 weeks, then shear strength, orientation function, crystallinity and molecular weight were measured. As a result, twist-orientation improves the initial torsional strength of PLA screw without the decrease in initial shear strength. In addition, the shear strength on twist-oriented screw is equivalent that of non-twist oriented screw during immersion until 24 weeks. This result shown that the twist-orientation does not decrease shear strength after immersion.

  2. Polylactic acid trays for fresh-food packaging: A Carbon Footprint assessment.

    Science.gov (United States)

    Ingrao, Carlo; Tricase, Caterina; Cholewa-Wójcik, Agnieszka; Kawecka, Agnieszka; Rana, Roberto; Siracusa, Valentina

    2015-12-15

    This paper discusses application of Carbon Footprint (CF) for quantification of the 100-year Global Warming Potential (GWP100) associated with the life cycle of polylactic acid (PLA) trays for packaging of fresh foods. A comparison with polystyrene (PS)-based trays was done considering two different transport system scenarios for PLA-granule supply to the tray production firm: a transoceanic freight vessel and an intercontinental freight aircraft. Doing so enabled estimation of the influence of the transportation phase on the GHG-emission rate associated with the PLA-trays' life cycle. From the assessment, the GWP100 resulted to be mainly due to PLA-granulate production and to its transportation to the tray manufacturing facility. Also, the study documented that, depending upon the transport system considered, the CF associated with the life cycle of the PLA trays can worsen so much that the latter are no longer GHG-emission saving as they are expected to be compared to the PS ones. Therefore, based upon the findings of the study, it was possible for the authors to understand the importance and the need of accounting for the transport-related issues in the design of PLA-based products, thus preserving their environmental soundness compared to traditional petroleum-based products. In this context, the study could be used as the base to reconsider the merits of PLA usage for product manufacturing, especially when high distances are implied, as in this analysed case. So, the authors believe that new research and policy frameworks should be designed and implemented for both development and promotion of more globally sustainable options. PMID:26282773

  3. Exploring the effect of cellulose nanowhiskers isolated from oil palm biomass on polylactic acid properties.

    Science.gov (United States)

    Haafiz, M K Mohamad; Hassan, Azman; Khalil, H P S Abdul; Fazita, M R Nurul; Islam, Md Saiful; Inuwa, I M; Marliana, M M; Hussin, M Hazwan

    2016-04-01

    In this work, polylactic acid (PLA) reinforced cellulose nanowhiskers (CNW) were prepared through solution casting technique. The CNW was first isolated from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) by using 64% H2SO4 and was designated as CNW-S. The optical microscopy revealed that the large particle of OPEFB-MCC has been broken down by the hydrolysis treatment. The atomic force microscopy confirmed that the CNW-S obtained is in nanoscale dimension and appeared in individual rod-like character. The produced CNW-S was then incorporated with PLA at 1, 3, and 5 parts per hundred (phr) resins for the PLA-CNW-S nanocomposite production. The synthesized nanocomposites were then characterized by a mean of tensile properties and thermal stability. Interestingly to note that incorporating of 3 phr/CNW-S in PLA improved the tensile strength by 61%. Also, CNW-S loading showed a positive impact on the Young's modulus of PLA. The elongation at break (Eb) of nanocomposites, however, decreased with the addition of CNW-S. Field emission scanning electron microscopy and transmission electron microscopy revealed that the CNW-S dispersed well in PLA at lower filler loading before it started to agglomerate at higher CNW-S loading (5phr). The DSC analysis of the nanocomposites obtained showed that Tg,Tcc and Tm values of PLA were improved with CNW-S loading. The TGA analysis however, revealed that incopreated CNW-S in PLA effect the thermal stability (T10,T50 and Tmax) of nanocomposite, where it decrease linearly with CNW-S loading. PMID:26772914

  4. Poly(lactic acid)/TiO{sub 2} nanocomposites as alternative biocidal and antifungal materials

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, Carmen; Ochoa, Almudena [POLCA, Departamento de Ingeniería Mecánica, Química y Diseño Industrial, Escuela Técnica Superior de Ingeniería y Diseño Industrial, Universidad Politécnica de Madrid, Ronda de Valencia 3, Madrid (Spain); Ulloa, Maria Teresa; Alvarez, Eduardo [Programa de Microbiología y Micología. ICBM-Facultad de Medicina Universidad de Chile, Dirección, Avenida Independencia 1027, Comuna Independencia, Santiago (Chile); Canales, Daniel [Grupo Polímeros, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Casilla 40, Correo 33, Santiago (Chile); Zapata, Paula A., E-mail: paula.zapata@usach.cl [Grupo Polímeros, Facultad de Química y Biología, Universidad de Santiago de Chile, USACH, Casilla 40, Correo 33, Santiago (Chile)

    2015-12-01

    Poly(lactic acid) (PLA) composites with titanium oxide (TiO{sub 2}) ~ 10-nm nanoparticles were produced by the melting process and their main properties were evaluated. The nanoparticles are homogeneously dispersed in the matrix with a low degree of agglomeration, as seen by transmission electron microscopy (TEM). The crystallinity temperature increased ~ 12% when 5 wt.% of TiO{sub 2} was added, showing that the nanoparticles acted as nucleating agents this trend was confirmed by optical images. The elastic modulus increased ~ 54% compared to neat PLA at 5 wt.% of nanoparticles. Despite these improvements, PLA/TiO{sub 2} nanocomposites showed lower shear viscosity than neat PLA, possibly reflecting degradation of the polymer due to the particles. Regarding biocidal properties, after 2 h of contact the PLA/TiO{sub 2} composites with 8 wt.% TiO{sub 2} showed a reduction of Escherichia coli colonies of ~ 82% under no UVA irradiation compared to pure PLA. This biocidal characteristic can be increased under UVA irradiation, with nanocomposites containing 8 wt.% TiO{sub 2} killing 94% of the bacteria. The PLA/TiO{sub 2} nanocomposites with 8 wt.% were also 99.99% effective against Aspergillus fumigatus under the UVA irradiation. - Highlights: • PLA composites with titanium oxide (10 nm) were produced by the melting process. • The crystallinity temperature increased ~ 12% when 5 wt.% of TiO{sub 2} was added. • The elastic modulus increased ~ 54% compared to neat PLA. • The PLA/TiO{sub 2} composites showed a reduction of Escherichia coli colonies of 94%. • The PLA/TiO{sub 2} nanocomposites with 8 wt.% were also 99.99% effective against fungi.

  5. Exploratory study on the pyrolysis and PAH emissions of polylactic acid

    Science.gov (United States)

    Chien, Yi-Chi; Liang, Chenju; Yang, Shu-hua

    2011-01-01

    The emission factors for 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) from the polylactic acid (PLA) pyrolysis and the decomposition mechanism were investigated in this study. The fragments and gas compositions using on-line thermogravimetry-mass spectrometry (TG-MS) were determined. A temperature series of 7 fragments was analyzed in helium, and was found to include: m/z = 16, which may represent methane; 28, which may be carbon monoxide; 44, which may be acetaldehyde; 56, which may be methylketene, 144, which may be oligomers of lactide. In addition, there are little amount of 100, and 200 which are oligomers of lactides observed in the pyrolysis of PLA. The pyrolysis of PLA is a non-radical, backbiting ester interchange reaction involving the OH chain ends. Depending on the size of the cyclic transition state, the product can be a lactide molecule, an oligomeric ring with more than two repeat units, methylketene, or acetaldehyde. Carbon monoxide and methane are contributions from the decomposition of acetaldehyde. Experimentally, not detected (n.d.)-40.47 μg of 16 PAH emissions were determined from per gram of PLA pyrolysis. The PAH profiles showed a predominance of naphthalene (58.9%), phenanthrene (12.5%), and fluoranthene (5.9%). The total PAH emissions for PLA pyrolysis is significantly lower than the values associated with PLA combustion. From the viewpoint of air pollution control, this result suggests that pyrolysis seems a better alternative than combustion for the disposal of waste PLA. Also, since pyrolysis is the first step for an incineration process, these results can provide important information on the control of PAHs formation for a commercialized incinerator.

  6. Conformational Footprint in Hydrolysis-Induced Nanofibrillation and Crystallization of Poly(lactic acid).

    Science.gov (United States)

    Xu, Huan; Yang, Xi; Xie, Lan; Hakkarainen, Minna

    2016-03-14

    The origin of hydrolysis-induced nanofibrillation and crystallization, at the molecular level, was revealed by mapping the conformational ordering during long-term hydrolytic degradation of initially amorphous poly(lactic acid) (PLA), a representative model for degradable aliphatic polyesters generally displaying strong interplay between crystallization and hydrolytic erosion. The conformational regularization of chain segments was essentially the main driving force for the morphological evolution of PLA during hydrolytic degradation. For hydrolysis at 37 °C, no significant structural variations were observed due to the immobilization of "frozen" PLA chains. In contrast, conformational ordering in PLA was immediately triggered during hydrolysis at 60 °C and was responsible for the transition from random coils to disordered trans and, further, to quasi-crystalline nanospheres. On the surfaces, the head-by-head absorption and joining of neighboring nanospheres led to nanofibrillar assemblies following a "gluttonous snake"-like manner. The length and density of nanofibers formed were in close relation to the hydrolytic evolution, both of which showed a direct rise in the initial 60 days and then a gradual decline. In the interior, presumably the high surface energy of the nanospheres allowed for the preferential anchoring and packing of conformationally ordered chains into lamellae. In accordance with the well-established hypothesis, the amorphous regions were attacked prior to the erosion of crystalline entities, causing a rapid increase of crystallinity during the initial 30 days, followed by a gradual fall until 90 days. In addition to adequate illustration of hydrolysis-induced variations of crystallinity, our proposed model elucidates the formation of spherulitic nuclei featuring an extremely wide distribution of diameters ranging from several nanometers to over 5 μm, as well as the inferior resistance to hydrolysis observed for the primary nuclei. Our work

  7. Properties of poly(lactic acid nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

    Directory of Open Access Journals (Sweden)

    K. Fukushima

    2012-11-01

    Full Text Available Poly(lactic acid (PLA based nanocomposites based on 5 wt.% of an organically modified montmorillonite (CLO, unmodified sepiolite (SEP and organically modified zirconium phosphonate (ZrP were obtained by melt blending. Wide angle X-ray scattering (WAXS and scanning electron microscopy (SEM analysis showed a different dispersion level depending on the type and functionalisation of nanoparticles. Differenctial scanning calorimetric (DSC analysis showed that PLA was able to crystallize on heating, and that the addition of ZrP could promote extent of PLA crystallization, whereas the presence of CLO and SEP did not significantly affect the crystallization on heating and melting behaviour of PLA matrix. Dynamic Mechanical Thermoanalysis (DMTA results showed that addition of all nanoparticles brought considerable improvements in E' of PLA, resulting in a remarkable increase of elastic properties for PLA nanocomposites. The melt viscosity and dynamic shear moduli (G',G" of PLA nanocomposites were also enhanced significantly by the presence of CLO and SEP, and attributed to the formation of a PLA/nanoparticle interconnected structure within the polymer matrix. The oxygen permeability of PLA did not significantly vary upon addition of SEP and ZrP nanoparticles. Only addition of CLO led to about 30% decrease compared to PLA permeability, due to the good clay dispersion and clay platelet-like morphology. The characteristic high transparency of PLA in the visible region was kept upon addition of the nanoparticles. Based on these achievements, a high potential of these PLA nanocomposites in sustainable packaging applications could be envisaged.

  8. Poly(lactic acid)/TiO2 nanocomposites as alternative biocidal and antifungal materials

    International Nuclear Information System (INIS)

    Poly(lactic acid) (PLA) composites with titanium oxide (TiO2) ~ 10-nm nanoparticles were produced by the melting process and their main properties were evaluated. The nanoparticles are homogeneously dispersed in the matrix with a low degree of agglomeration, as seen by transmission electron microscopy (TEM). The crystallinity temperature increased ~ 12% when 5 wt.% of TiO2 was added, showing that the nanoparticles acted as nucleating agents this trend was confirmed by optical images. The elastic modulus increased ~ 54% compared to neat PLA at 5 wt.% of nanoparticles. Despite these improvements, PLA/TiO2 nanocomposites showed lower shear viscosity than neat PLA, possibly reflecting degradation of the polymer due to the particles. Regarding biocidal properties, after 2 h of contact the PLA/TiO2 composites with 8 wt.% TiO2 showed a reduction of Escherichia coli colonies of ~ 82% under no UVA irradiation compared to pure PLA. This biocidal characteristic can be increased under UVA irradiation, with nanocomposites containing 8 wt.% TiO2 killing 94% of the bacteria. The PLA/TiO2 nanocomposites with 8 wt.% were also 99.99% effective against Aspergillus fumigatus under the UVA irradiation. - Highlights: • PLA composites with titanium oxide (10 nm) were produced by the melting process. • The crystallinity temperature increased ~ 12% when 5 wt.% of TiO2 was added. • The elastic modulus increased ~ 54% compared to neat PLA. • The PLA/TiO2 composites showed a reduction of Escherichia coli colonies of 94%. • The PLA/TiO2 nanocomposites with 8 wt.% were also 99.99% effective against fungi

  9. Bioplastic composite foam prepared from poly(lactic acid) and natural wood flour

    Science.gov (United States)

    Suwannakas, Pokkes; Petrchwattana, Nawadon; Covavisaruch, Sirijutaratana

    2016-03-01

    The major drawbacks of Poly(lactic acid) (PLA) bioplastic are its cost and brittleness. This study aims to reduce the cost by foaming PLA reinforced with wood flour. A series of PLA/ natural fiber (WF) composite was prepared by using WF of selected conifers up to 5 wt%; each composite formulation was then foamed using 2 wt% of Azodicarbonamide (ADC) as chemical foaming agent. ADC effectively reduced the density of PLA and the PLA/WF composite foam by about 45% to 0.64 g/cm3 from 1.24 g/cm3 of neat PLA and 1.26 g/cm3 of PLA/WF composites when 2 wt% ADC was applied. Mechanical behaviors in terms of compressive and impact properties were investigated. With the presence of WF, the compressive stress increased with the WF content due to the good interfacial adhesion between the PLA matrix and the WF. This was verified by microscopic observation, leading to efficient stress transfer at the interface between PLA matrix and the WF. The presence of WF raised the specific compressive modulus and strength of PLA/WF composites to around 0.94 GPa.cm3/g and 2.65 MPa.cm3/g but foaming the PLA or the PLA/WF composites led to a dramatic reduction of the compressive modulus to 0.2-0.4 GPa.cm3/g, implying that the PLA and the PLA/WF foams had become softened. This was evidently observed in the significant reduction of hardness coupled with the vast drop of stress required to compressively deform the foams.

  10. Effects of a chitosan membrane coated with polylactic and polyglycolic acid on bone regeneration in a rat calvarial defect

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the effects of a chitosan membrane coated with polylactic and polyglycolic acid (PLGA) on bone regeneration in a rat calvarial defect. Surgical implantation of chitosan membranes resulted in enhanced local bone formation at both 2 and 8 weeks. In conclusion, the chitosan membrane coated with PLGA had a significant potential to induce bone formation in the rat calvarial defect model. Within the selected PLGA dose range and observation intervals, there appeared to be no meaningful differences in bone formation

  11. Flash co-pyrolysis of biomass with polylactic acid. Part 1: Influence on bio-oil yield and heating value

    OpenAIRE

    Cornelissen, Tom; Yperman, Jan; REGGERS, Guy; Schreurs, Sonja; Carleer, Robert

    2008-01-01

    High amounts of water present in bio-oil are one of the major drawbacks for its utilisation as a fuel. One technology that shows the potential to satisfy the demand for bio-oil with a reduced water content is the flash co-pyrolysis of biomass with polylactic acid, PLA. The influence of PLA on the pyrolysis of willow is investigated with a semi-continuous home-built pyrolysis reactor. Flash co-pyrolysis of willow/PLA blends (10: 1, 3: 1, 1:1 and 1:2) show synergetic interaction. ...

  12. Effects of a chitosan membrane coated with polylactic and polyglycolic acid on bone regeneration in a rat calvarial defect

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Ui-Won [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Song, Kun-Young [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chang-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Lee, Yong-Keun [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of); Cho, Kyoo-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chong-Kwan [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of)

    2007-09-15

    The purpose of this study was to evaluate the effects of a chitosan membrane coated with polylactic and polyglycolic acid (PLGA) on bone regeneration in a rat calvarial defect. Surgical implantation of chitosan membranes resulted in enhanced local bone formation at both 2 and 8 weeks. In conclusion, the chitosan membrane coated with PLGA had a significant potential to induce bone formation in the rat calvarial defect model. Within the selected PLGA dose range and observation intervals, there appeared to be no meaningful differences in bone formation.

  13. New Composition of Maleic-Anhydride-Grafted Poly(Lactic Acid)/Rice Husk with Methylenediphenyl Diisocyanate

    OpenAIRE

    Tsou, Chi-Hui; Hung, Wei-Song; Chin-San WU; Chen, Jui-Chin; Chi-Yuan HUANG; Chiu, Shih-Hsuan; Chih-Yuan TSOU; Yao, Wei-Hua; Shang-Ming LIN; Chih-Kuei CHU; Hu, Chien-Chieh; Kueir-Rarn LEE; Suen, Maw-Cherng

    2014-01-01

    Maleic-anhydride-grafted poly(lactic acid) (PLA-g-MAH) was prepared and blended with rice husk (RH). Methylenediphenyl diisocyanate (MDI) was used as the coupling agent for combining RH with PLA-g-MAH, which improved the poor interfacial adhesion between PLA and RH. Various PLA-g-MAH/RH blends, with and without MDI, were prepared by melt processing using a brabender. The effects that inclusion and distribution of MDI had on the mechanical properties and thermal behaviors of the composites wer...

  14. Hybrid poly(lactic acid)/nanocellulose/nanoclay composites with synergistically enhanced barrier properties and improved thermomechanical resistance

    DEFF Research Database (Denmark)

    Trifol Guzman, Jon; Plackett, David; Sillard, Cecile;

    2016-01-01

    Poly(lactic acid) (PLA)‐based hybrid nanocomposites (PLA, nanoclay and nanocellulose) were prepared by reinforcing neat PLA with commercially available nanoclay (Cloisite C30B) and nanocellulose, in the form of either partially acetylated cellulose nanofibres (CNFs) or nanocrystalline cellulose......) through a reduction of up to 90% in OTR and a further reduction in the water vapour transmission rate of up to 76%. In addition, the nanocomposite films showed improved thermomechanical resistance and improved crystallisation kinetics while maintaining high film transparency. This makes the hybrid PLA...

  15. Poly(lactic) acid fibers loaded with mesoporous silica for potential applications in the active food packaging

    Science.gov (United States)

    Cacciotti, Ilaria; Nanni, Francesca

    2016-06-01

    Multifunctional fibrous systems based on poly(lactic) acid (PLA), mesoporous silica (SiO2) and ascorbic acid (AA) were produced by means of electrospinning technique, for potential applications in the active food packaging sector, as platform for the controlled release of antioxidant and/or antimicrobial agents with the additional filtering function. The ascorbic acid was physisorbed on the surface of mesoporous silica in order to stabilize it and to extend its antioxidant action. The influence of mesoporous silica and ascorbic acid on the microstructural and mechanical properties was investigated, revealing a revelant mechanical reinforcement in the case of fibers loaded only with SiO2 and a decrement in the case of SiO2 with physisorbed ascorbic acid, due to the worse interface between the fillers and the polymeric matrix.

  16. Biodegradation of cycloalkane carboxylic acids in oil sand tailings

    International Nuclear Information System (INIS)

    The biodegradation of both an n-alkane and several carboxylated cycloalkanes was examined experimentally within tailings produced by the extraction of bitumen from the Athabasca oil sands. The carboxylated cycloalkanes examined were structurally similar to naphthenic acids that have been associated with the acute toxicity of oil sand tailings. The biodegradation potential of naphthenic acids was estimated by determining the biodegradation of both the carboxylated cycloalkanes and hexadecane in oil sand tailings. Carboxylated cycloalkanes were biodegraded within oil sands tailings, although compounds with methyl substitutions on the cycloalkane ring were more resistant to microbial degradation. Microbial activity against hexadecane and certain carboxylated cycloalkanes was found to be nitrogen and phosphorus limited. 21 refs., 3 refs., 1 tab

  17. Composition dependence of the synergistic effect of nucleating agent and plasticizer in poly(lactic acid: A Mixture Design study

    Directory of Open Access Journals (Sweden)

    M. K. Fehri

    2016-04-01

    Full Text Available Blends consisting of commercial poly(lactic acid (PLA, poly(lactic acid oligomer (OLA8 as plasticizer and a sulfonic salt of a phthalic ester and poly(D-lactic acid as nucleating agents were prepared by melt extrusion, following a Mixture Design approach, in order to systematically study mechanical and thermal properties as a function of composition. The full investigation was carried out by differential scanning calorimetry (DSC, dynamic mechanical thermal analysis (DMTA and tensile tests. The crystallization half-time was also studied at 105 °C as a function of the blends composition. A range of compositions in which the plasticizer and the nucleation agent minimized the crystallization half-time in a synergistic way was clearly identified thanks to the application of the Mixture Design approach. The results allowed also the identification of a composition range to maximize the crystallinity developed during the rapid cooling below glass transition temperature in injection moulding, thus allowing an easier processing of PLA based materials. Moreover the mechanical properties were discussed by correlating them to the chemical structural features and thermal behaviour of blends.

  18. Electrospun polycaprolactone/polylactic acid nanofibers as an artificial nerve conduit

    International Nuclear Information System (INIS)

    Development of conduits made of biodegradable nanofibers is gaining substantial interest due to their suitability for nerve regeneration. Among all polymeric nanofibers PCL (Poly-Caprolactone) is distinctively found for mechanical stability and PLLA (Poly (L-Lactic Acid)) for relatively faster biodegradability. The aim of this study is to investigate blending compatibility between PCL and PLLA and the ability to fabricate nanofibers conduits via electro spinning. The PCL-PLLA nano-fiber tubular made from different blend ratios of PCL-PLLA were electro spun. The electro spun nanofibers were continuously deposited over high speed rotating mandrel to fabricate nanofibers conduit having inner diameter of 2mm and the wall thickness of 55-65 m. The diameters of nano-fibers were between 715-860nm. FTIR (Fourier Transform Infrared) spectroscopy used to analyze chemical change in the blends of nerve conduits, which revealed that the PCL-PLLA blend nanofiber exhibit characteristic peaks of both PCL and PLLA and was composition dependent. The crystallinity of PCL-PLLA tubes were studied using WAXD (Wide Angle Xray Diffraction). The morphology of nanofibers were investigated under SEM (Scanning Electron Microscope). The mechanical properties of the conduits were also tested; the Young's modulus obtained for small diameter was 10MPa, twice as high as larger diameter. (author)

  19. Electrospun Polycaprolactone/Polylactic Acid Nanofibers as an Artificial Nerve Conduit

    Directory of Open Access Journals (Sweden)

    Zeeshan Ali Khatri

    2014-07-01

    Full Text Available Development of conduits made of biodegradable nanofibers is gaining substantial interest due to their suitability for nerve regeneration. Among all polymeric nanofibers PCL (Poly ?-Caprolactone is distinctively found for mechanical stability and PLLA (Poly (L-Lactic Acid for relatively faster biodegradability. The aim of this study is to investigate blending compatibility between PCL and PLLA and the ability to fabricate nanofibers conduits via electro spinning. The PCL-PLLA nano-fiber tubular made from different blend ratios of PCL-PLLA were electro spun. The electro spun nanofibers were continuously deposited over high speed rotating mandrel to fabricate nanofibers conduit having inner diameter of 2mm and the wall thickness of 55-65µm. The diameters of nano-fibers were between 715-860nm. FTIR (Fourier Transform Infrared spectroscopy used to analyze chemical change in the blends of nerve conduits, which revealed that the PCL-PLLA blend nanofiber exhibit characteristic peaks of both PCL and PLLA and was composition dependent. The crystallinity of PCL-PLLA tubes were studied using WAXD (Wide Angle Xray Diffraction. The morphology of nanofibers were investigated under SEM (Scanning Electron Microscope. The mechanical properties of the conduits were also tested; the Young?s modulus obtained for small diameter was 10MPa, twice as high as larger diameter.

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

    Science.gov (United States)

    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

  1. Review on Chlorobenzoic Acids Biodegradation and Their Environmental Impacts

    Institute of Scientific and Technical Information of China (English)

    LuWenming; QiYun; ZhaoLin; TanXin

    2005-01-01

    Chlorobenzoic Acids are toxic organic compounds largely distributed in soils and sediments. They can be degraded to various products by microorgans. This paper is a review of the literature on biodegradability of the chlorobenzoic acids. The degradation pathways, degradation genes, role of transposable elements, and construction of strains are discussed. A brief introduction is given on the environmental impacts and the pollution control.

  2. Use of poly(lactic acid) amendments to promote the bacterial fixation of metals in zinc smelter tailings.

    Science.gov (United States)

    Edenborn, H M

    2004-04-01

    The ability of poly(lactic acid) (PLA) to serve as a long-term source of lactic acid for bacterial sulfate reduction activity in zinc smelter tailings was investigated. Solid PLA polymers mixed in water hydrolyzed abiotically to release lactic acid into solution over an extended period of time. The addition of both PLA and gypsum was required for indigenous bacteria to lower redox potential, raise pH, and stimulate sulfate reduction activity in highly oxidized smelter tailings after one year of treatment. Bioavailable cadmium, copper, lead and zinc were all lowered significantly in PLA/gypsum treated soil, but PLA amendments alone increased the bioavailability of lead, nickel and zinc. Similar PLA amendments may be useful in constructed wetlands and reactive barrier walls for the passive treatment of mine drainage, where enhanced rates of bacterial sulfate reduction are desirable. PMID:14693443

  3. Evaluation of biocompatibility and toxicity of biodegradable poly (DL-lactic acid) films.

    Science.gov (United States)

    Li, Rui-Yun; Liu, Zhi-Gang; Liu, Huan-Qiu; Chen, Lei; Liu, Jian-Feng; Pan, Yue-Hai

    2015-01-01

    Regeneration and functional recovery of nerves after peripheral nerve injury is the key to peripheral nerve repair. One of the putative therapeutic strategies is to use anti-adhesion polymer films, made of polymeric biomaterials. Recently, a novel biodegradable poly (DL-lactic acid) (PDLLA) film has been prepared using a method of phase transformation with biodegradable polylactic acid polymer as the substrate. This novel, anti-adhesion film has a porous structure, which provides better mechanical properties, better flexibility, more complete diffusion through the polymer of tissue biologic factors like growth factors, and more controllable degradation compared to traditional non-porous films. Little is known, however, about the in vitro and in vivo biocompatibility and cytotoxicity of this type of PDLLA film. Therefore, our aim was to evaluate the biocompatibility and cytotoxicity of this novel PDLLA film using various experimental methods, including a skin irritation test, MTT analysis, and the mouse bone marrow cell micronucleus test, as well as hematology or clinical chemistry measurements in rats after receiving sciatic nerve transection and anastomosis with wrapping of the anastomosis with DLLA films. We demonstrated that exposure to PDLLA film extracts did not generate apparent erythema or edema in rabbit skin and had no effect on the proliferation of Vero cells. Additionally, treatment with PDLLA film extracts did not alter the incidence of micronucleated polychromatic erythrocytes as compared with saline Treated group. Furthermore, implantation of PDLLA film did not alter liver or renal function as measured by serum levels of ALT, AST, TP, A/G, Cr, and BUN, and pathologic examinations showed that implantation of PDLLA film did not cause pathologic changes to the rat liver, kidney, pancreas, or spleen. Taken together, these results suggest that PDLLA films have excellent biocompatibility and no obvious toxicity in vivo, and may be used to prevent nerve

  4. Direct investigations on strain-induced cold crystallization behavior and structure evolutions in amorphous poly(lactic acid) with SAXS and WAXS measurements

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Li, Hongfei; Zhang, Wenyang;

    2016-01-01

    Strain-induced cold crystallization behavior and structure evolution of amorphous poly(lactic acid) (PLA) stretched within 70-90 degrees C were investigated via in situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements as well as differential scan...

  5. Controlled release of linalool using nanofibrous membranes of poly(lactic acid) obtained by electrospinning and solution blow spinning: A comparative study

    Science.gov (United States)

    The controlled-release of natural plant oils such as linalool is of interest in therapeutics, cosmetics, and antimicrobial and larvicidal products. The present study reports the release characteristics of linalool encapsulated at three concentrations (10, 15 and 20 wt.%) in poly(lactic acid) nanofib...

  6. Physicochemical properties of poly(lactic acid-co-glycolic acid film modified via blending with poly(butyl acrylate-co-methyl methacrylate

    Directory of Open Access Journals (Sweden)

    Guoquan Zhu

    2013-01-01

    Full Text Available A series of poly(lactic acid-co-glycolic acid (PLGA/poly(butyl acrylate-co-methyl methacrylate (P(BA-co-MMA blend films with different P(BA-co-MMA mole contents were prepared by casting the polymer blend solution in chloroform. Surface morphologies of the PLGAP(BA-co-MMA blend films were studied by scanning electron microscopy (SEM. Thermal, mechanical, and chemical properties of PLGAP(BA-co-MMA blend films were investigated by differential scanning calorimeter (DSC, thermogravimetric analysis (TGA, tensile tests, and surface contact angle tests. The introduction of P(BA-co-MMA could modify the properties of PLGA films.

  7. Superparamagnetic iron oxide--loaded poly(lactic acid)-D-alpha-tocopherol polyethylene glycol 1000 succinate copolymer nanoparticles as MRI contrast agent.

    Science.gov (United States)

    Prashant, Chandrasekharan; Dipak, Maity; Yang, Chang-Tong; Chuang, Kai-Hsiang; Jun, Ding; Feng, Si-Shen

    2010-07-01

    We developed a strategy to formulate supraparamagnetic iron oxides (SPIOs) in nanoparticles (NPs) of biodegradable copolymer made up of poly(lactic acid) (PLA) and d-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS) for medical imaging by magnetic resonance imaging (MRI) of high contrast and low side effects. The IOs-loaded PLA-TPGS NPs (IOs-PNPs) were prepared by the single emulsion method and the nanoprecipitation method. Effects of the process parameters such as the emulsifier concentration, IOs loading in the nanoparticles, and the solvent to non-solvent ratio on the IOs distribution within the polymeric matrix were investigated and the formulation was then optimized. The transmission electron microscopy (TEM) showed direct visual evidence for the well dispersed distribution of the IOs within the NPs. We further investigated the biocompatibility and cellular uptake of the IOs-PNPs in vitro with MCF-7 breast cancer cells and NIH-3T3 mouse fibroblast in close comparison with the commercial IOs imaging agent Resovist. MRI imaging was further carried out to investigate the biodistribution of the IOs formulated in the IOs-PNPs, especially in the liver to understand the liver clearance process, which was also made in close comparison with Resovist. We found that the PLA-TPGS NPs formulation at the clinically approved dose of 0.8 mg Fe/kg could be cleared within 24 h in comparison with several weeks for Resovist. Xenograft tumor model MRI confirmed the advantages of the IOs-PNPs formulation versus Resovist through the enhanced permeation and retention (EPR) effect of the tumor vasculature. PMID:20434210

  8. Mechanical Properties of Poly(lactic acid) Sheet Reinforced with Microfibrillated Cellulose from Corn Cobs

    OpenAIRE

    Deejam Prapatsorn; Charuchinda Sireerat

    2015-01-01

    In this study, cellulose was extracted from corn cobs by successive hot NaOH solution and followed by H2O2 bleaching. XRD pattern show characteristic peak of Cellulose I. Microfibrillated cellulose (MFC) was successfully prepared by dissolving the extracted cellulose in NaOH/urea solution, shearing in a homogenizer and finally by freezing and thawing. To improve strength of MFC, MFC was physically crosslinked using PVA by freezing and thawing. The crosslinked MFC/PVA was added to poly(lactic ...

  9. Hydrothermal in situ preparation of TiO2 particles onto poly(lactic acid) electrospun nanofibres

    Science.gov (United States)

    Gupta, Kamal K.; Mishra, Pradeep K.; Srivastava, Pradeep; Gangwar, Mayank; Nath, Gopal; Maiti, Pralay

    2013-01-01

    The novel poly(lactic acid) (PLA)/TiO2 hybrid nanofibres are produced via electrospinning technique. Hydrolysed titanium precursor has been electrosprayed simultaneously on the continuous electrospun PLA nanofibres surface. The adhered amorphous titania has been transformed into TiO2 particle through hydrothermal treatment for different times. The phase structure has been worked out using XRD, FTIR, XPS and Raman spectroscopy. The predominant phase is anatase with a small extent of brookite phase after the hydrothermal treatment. The size and location of TiO2 particle have been determined using SEM micrographs. The orderness of the PLA crystallites has been checked using XRD patterns before and after hydrothermal treatment. UV absorption capability of the titania coated nanofibres has been enhanced to a significant level. The antimicrobial activity of the hybrids has been verified using two different microorganisms (gram negative Escherichia coli and gram positive Staphylococcus aureus bacteria) and 70% reduction of antimicrobial activity has been reported.

  10. Bark polyflavonoids from Pinus radiata as functional building-blocks for polylactic acid (PLA-based green composites

    Directory of Open Access Journals (Sweden)

    D. E. Garcia

    2016-10-01

    Full Text Available Polylactic acid (PLA was melt-blended with Pinus radiata unmodified and modified (hydroxypropyled bark polyflavonoids in order to use such polyphenolic building-blocks as functional additives for envisaged applications. Rheological, morphological, molecular, thermal, and flexural properties were studied. Polyflavonoids improved blend processability in terms of short-time mixing. Furthermore, hydroxypropylated polyflavonoids improve miscibility in binary and ternary blends. Blend-composition affects crystallization-, melting-, and glass transition-temperature of PLA, as well as thermal resistance, and flexural properties of the blends. Polyflavonoids induced PLA-crystallization, and polymer-chain decomposition. Modified and unmodified bark polyflavonoids from radiata pine can be used successfully in PLA-based green composites beyond the food-packaging applications. The high compatibility between PLA and hydroxypropyled polyflavonoids highlights the potential of such phenolic derivatives for PLA-based material design.

  11. Mass Attenuation Coefficients of Binderless and Polylactic Acid Added Oil Palm Trunk Particleboard in the Diagnostic Energy Range

    Directory of Open Access Journals (Sweden)

    Mohana Baskaran

    2015-01-01

    Full Text Available Two types of oil palm trunk particleboards namely binderless and polylactic acid (PLA added board were manufactured with a target density of 1.0 g/cm3. The mass attenuation coefficients of the binderless and PLA added particleboards were determined by using X-ray fluorescence (XRF photons emanating from high purity metal plates. The energies of the XRF emitted from those metal plates were in the range of 16.59 keV– 25.26 keV. The experimental values of the mass attenuation coefficients of the binderless particleboards and the XCOM calculated values for water are comparable. These results suggest that binderless particleboards have the potential to be a phantom material at diagnostic photon energies.

  12. Poly(dopamine) coating of 3D printed poly(lactic acid) scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Chia-Tze [School of Dentistry, Chung Shan Medical University, Taichung City, Taiwan (China); Department of Stomatology, Chung Shan Medical University Hospital, Taichung City, Taiwan (China); Lin, Chi-Chang [Department of Chemical and Materials Engineering, Tunghai University, Taichung City, Taiwan (China); Chen, Yi-Wen; Yeh, Chia-Hung [3D Printing Medical Research Center, China Medical University Hospital, Taichung City, Taiwan (China); Fang, Hsin-Yuan [3D Printing Medical Research Center, China Medical University Hospital, Taichung City, Taiwan (China); Department of Thoracic Surgery, China Medical University Hospital, Taichung City, Taiwan (China); School of Medicine, College of Medicine, College of Public Health, Taichung City, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [3D Printing Medical Research Center, China Medical University Hospital, Taichung City, Taiwan (China)

    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. - Highlights: • A simple method of 3D printed poly(lactic acid) scaffold coated with PDA • Promoted proliferation of hADSCs on PDA/PLA scaffolds • Increased collagen I, cell cycle, and cell adhesion with a high PDA content • Up-regulation of angiogenic and osteogenic of hADSCs • A promising method for bioinspired surface modification on PLA using PDA.

  13. Poly(dopamine) coating of 3D printed poly(lactic acid) scaffolds for bone tissue engineering

    International Nuclear Information System (INIS)

    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. - Highlights: • A simple method of 3D printed poly(lactic acid) scaffold coated with PDA • Promoted proliferation of hADSCs on PDA/PLA scaffolds • Increased collagen I, cell cycle, and cell adhesion with a high PDA content • Up-regulation of angiogenic and osteogenic of hADSCs • A promising method for bioinspired surface modification on PLA using PDA

  14. Preparation and properties of nanocomposites based on poly(lactic acid) and functionalized TiO2

    International Nuclear Information System (INIS)

    Inorganic/polymer nanocomposites are significant materials due to their unique combination of properties. Lactic acid (LA) was used to modify the TiO2 surface by the Ti-carboxylic coordination bonds, and LA can chemically bond TiO2 nanoparticles to form functionalized oligomeric-poly(lactic acid)-grafted TiO2 nanoparticles (g-TiO2). The resulting g-TiO2 was added to the poly(lactic acid) (PLA) matrix to prepare PLA/TiO2 nanocomposites via melting processing. The structure and properties of the nanocomposites were subsequently investigated via Fourier transform infrared spectroscopy, gel permeation chromatography, scanning electron microscopy, transmission electron microscopy, polar optical microscopy, differential scanning calorimetry, dynamic rheometer and universal testing machine. The results showed that g-TiO2 nanocomposites had a much lower degree of agglomeration than bare TiO2. The introduction of g-TiO2 into PLA matrix improved the crystallinity of the composites. The functionalized nanoparticles played an important role in improving mechanical properties and reducing the complex viscosity of the nanocomposites due to its unique structure and the reasonable interfacial interaction between the nanoparticles and PLA matrix.

  15. Preparation and properties of nanocomposites based on poly(lactic acid) and functionalized TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yanbing; Li Wenda; Wang Xiuli; Xu Dayun [Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MoE), College of Chemistry, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064 (China); Wang Yuzhong, E-mail: yzwang@mail.scu.edu.cn [Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MoE), College of Chemistry, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064 (China)

    2009-06-15

    Inorganic/polymer nanocomposites are significant materials due to their unique combination of properties. Lactic acid (LA) was used to modify the TiO{sub 2} surface by the Ti-carboxylic coordination bonds, and LA can chemically bond TiO{sub 2} nanoparticles to form functionalized oligomeric-poly(lactic acid)-grafted TiO{sub 2} nanoparticles (g-TiO{sub 2}). The resulting g-TiO{sub 2} was added to the poly(lactic acid) (PLA) matrix to prepare PLA/TiO{sub 2} nanocomposites via melting processing. The structure and properties of the nanocomposites were subsequently investigated via Fourier transform infrared spectroscopy, gel permeation chromatography, scanning electron microscopy, transmission electron microscopy, polar optical microscopy, differential scanning calorimetry, dynamic rheometer and universal testing machine. The results showed that g-TiO{sub 2} nanocomposites had a much lower degree of agglomeration than bare TiO{sub 2}. The introduction of g-TiO{sub 2} into PLA matrix improved the crystallinity of the composites. The functionalized nanoparticles played an important role in improving mechanical properties and reducing the complex viscosity of the nanocomposites due to its unique structure and the reasonable interfacial interaction between the nanoparticles and PLA matrix.

  16. Enhancement of Mechanical and Dynamic Mechanical Properties of Hydrophilic Nanoclay Reinforced Polylactic Acid/Polycaprolactone/Oil Palm Mesocarp Fiber Hybrid Composites

    OpenAIRE

    Chern Chiet Eng; Nor Azowa Ibrahim; Norhazlin Zainuddin; Hidayah Ariffin; Wan Md Zin Wan Yunus; Yoon Yee Then

    2014-01-01

    In previous studies, the effect of the addition of 1 wt% hydrophilic nanoclay on polylactic acid (PLA)/polycaprolactone (PCL)/oil palm mesocarp fiber (OPMF) biocomposites was investigated by tensile properties, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The current studies focus on the effect of addition of 1 wt% hydrophilic nanoclay on mechanical (flexural and impact properties) and dynamic mechanical properties of composites. The composites were characterized ...

  17. Elaboration of poly(lactic acid)/halloysite nanocomposites by means of water assisted extrusion: structure, mechanical properties and fire performance

    OpenAIRE

    Stoclet, G.; Sclavons, Michel; Lecouvet, Benoît; Devaux, Jacques; Van Velthem, Pascal; Boborodea, Adrian; Bourbigot, S.; Sallem, Naïma

    2014-01-01

    Poly(lactic acid) (PLA)/halloysite nanotube (HNT) nanocomposites were prepared using a water assisted extrusion process. Morphology, structure, thermomechanical properties and flame retardant properties of these nanocomposites were compared to those obtained in the case of nanocomposites obtained via the conventional extrusion process. Whatever the synthesis route used, mechanical tests indicate that HNTs have a reinforcing effect ascribed, at least partially, to the dispersion of the HNTs in...

  18. Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

    International Nuclear Information System (INIS)

    Poly(lactic acid) (PLA)-grafted TiO2 particles were prepared by in situ melt polycondensation of lactic acid onto the surface of TiO2 nanoparticles. The resulting products were characterized by FTIR, XPS, TG-FTIR, XRD analysis and electron microscopy observation so as to have a better understanding of bonding between the graft polymer and nanoparticles. New characteristic peaks of Ti-carboxylic coordination bond, the changes in the relative intensities of the infrared absorption bands of graft polymer and the two decomposition stage of PLA-grafted TiO2 confirmed that PLA was grafted on the surface of TiO2 nanoparticles. By attachment of PLA, the PLA-grafted TiO2 samples exhibited much better dispersion and a slightly larger particle size than bare TiO2 particles. PLA-grafted TiO2 nanoparticles will find wide applications in biomedical and eco-friendly materials, especially as fillers in PLA matrix.

  19. Chemical Synthesis and Optical Properties of CdS Poly(Lactic Acid) Nanocomposites and Their Transparent Fluorescent Films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cai-Feng [Nanjing University of Technology; Cheng, Yu-Peng [Nanjing University of Technology; Xie, He-Yi [Nanjing University of Technology; Chen, Li [Nanjing University of Technology; Hu, Michael Z. [ORNL; Chen, Su [Nanjing University of Technology

    2011-01-01

    This paper describes the chemical synthesis of cadmium sulfide (CdS) polymer nanocomposites by covalently grafting poly(lactic acid) (PLA) onto the surfaces of CdS nanocrystals (NCs). Synthesis of the nanocomposites involved two steps. Lactic acid (LA) capped CdS NCs were first prepared by reacting cadmium chloride (CdCl2) with sodium sulfide (Na2S) using LA as the organic ligand in H2O/N,N-dimethylformamide (DMF) solution. Next CdS PLA nanocomposites were formed by in situ ring-opening polymerization of lactide on the surface of modified CdS NCs. Transparent fluorescent films were then successfully prepared by blending as-prepared CdS PLA nanocomposites with high-molecular-weight PLA. The as-prepared CdS NCs and their nanocomposites were studied by transmission electron microscopic imaging, thermogravimetric analyses, and spectroscopic measurements (ultraviolet-visible absorption and photoluminescence). The spectroscopic studies revealed that the CdS polymer nanocomposites exhibited good optical properties in terms of their photoluminescence and transparency.

  20. Melt electrospinning of poly(lactic acid) and polycaprolactone microfibers by using a hand-operated Wimshurst generator

    Science.gov (United States)

    Qin, Chong-Chong; Duan, Xiao-Peng; Wang, Le; Zhang, Li-Hua; Yu, Miao; Dong, Rui-Hua; Yan, Xu; He, Hong-Wei; Long, Yun-Ze

    2015-10-01

    A conventional melt electrospinning setup usually needs a large, heavy high-voltage power supply and cannot work without a plug (electricity supply). In this article, we report a new melt electrospinning setup based on a small hand-operated Wimshurst generator, which can avoid electrical interference between the high-voltage spinning system and the heating system, and make the setup very portable and safe. Poly(lactic acid) (PLA) and polycaprolactone (PCL) fibers with diameters of 15-45 μm were fabricated successfully by using this apparatus. Experimental parameters such as the rotational speed of the generator handle (a half turn to two turns per second) and the spinning distance (2-14 cm) were investigated. In addition, PLA and PCL fibers were directly melt-electrospun onto a pork liver, and the temperature and adhesiveness of the deposited fibers were studied. The results indicate that the apparatus and melt-electrospun polymer microfibers may be used in dressing for wound healing.A conventional melt electrospinning setup usually needs a large, heavy high-voltage power supply and cannot work without a plug (electricity supply). In this article, we report a new melt electrospinning setup based on a small hand-operated Wimshurst generator, which can avoid electrical interference between the high-voltage spinning system and the heating system, and make the setup very portable and safe. Poly(lactic acid) (PLA) and polycaprolactone (PCL) fibers with diameters of 15-45 μm were fabricated successfully by using this apparatus. Experimental parameters such as the rotational speed of the generator handle (a half turn to two turns per second) and the spinning distance (2-14 cm) were investigated. In addition, PLA and PCL fibers were directly melt-electrospun onto a pork liver, and the temperature and adhesiveness of the deposited fibers were studied. The results indicate that the apparatus and melt-electrospun polymer microfibers may be used in dressing for wound healing

  1. Production of Polylactic acid in laboratory scale, and characterising the thermal properties.

    OpenAIRE

    Basnet, Shristi

    2016-01-01

    This thesis presents findings from experimental research on producing biodegradable plastic from corn starch. A corn consists of many parts, among which starch is used essentially in food and bioplastic products. A starch is extracted from corn, then it is mixed plasticizers and some plastic additives for further synthesis. The synthesis and drying of starch based polymer was performed in Arcada Lab. The thermal analysis of the material were performed in the laboratories of Helsinki Universi...

  2. Biodegradability evaluation of polymers by ISO 14855-2.

    Science.gov (United States)

    Funabashi, Masahiro; Ninomiya, Fumi; Kunioka, Masao

    2009-10-01

    Biodegradabilities of polymers and their composites in a controlled compost were described. Polycaprolactone (PCL) and poly(lactic acid) (PLA) were employed as biodegradable polymers. Biodegradabilities of PCL and PLA samples in a controlled compost were measured using a Microbial Oxidative Degradation Analyzer (MODA) according to ISO 14855-2. Sample preparation method for biodegradation test according to ISO/DIS 10210 was also described. Effects of sizes and shapes of samples on biodegradability were studied. Reproducibility of biodegradation test of ISO 14855-2 by MODA was confirmed. Validity of sample preparation method for polymer pellets, polymer film, and polymer products of ISO/DIS 10210 for ISO 14855-2 was confirmed. PMID:20111676

  3. Treating cutaneous squamous cell carcinoma using 5-aminolevulinic acid polylactic-co-glycolic acid nanoparticle-mediated photodynamic therapy in a mouse model

    Directory of Open Access Journals (Sweden)

    Wang X

    2015-01-01

    Full Text Available Xiaojie Wang,1,2,* Lei Shi,2,* Qingfeng Tu,2 Hongwei Wang,3 Haiyan Zhang,2 Peiru Wang,2 Linglin Zhang,2 Zheng Huang,4 Feng Zhao,5 Hansen Luan,5 Xiuli Wang2 1Shanghai Skin Diseases Clinical College of Anhui Medical University, 2Shanghai Skin Disease Hospital, 3Huadong Hospital, Fudan University, Shanghai, 4MOE Key Laboratory of OptoElectronic Science and Technology for Medicine, Fujian Normal University, Fuzhou, 5National Pharmaceutical Engineering Research Center, China State Institute of Pharmaceutical Industry, Shanghai, People’s Republic of China *These authors contributed equally to this study Background: Squamous cell carcinoma (SCC is a common skin cancer, and its treatment is still difficult. The aim of this study was to evaluate the effectiveness of nanoparticle (NP-assisted 5-aminolevulinic acid (ALA delivery for topical photodynamic therapy (PDT of cutaneous SCC.Materials and methods: Ultraviolet-induced cutaneous SCCs were established in hairless mice. ALA-loaded polylactic-co-glycolic acid (PLGA NPs were prepared and characterized. The kinetics of ALA PLGA NP-induced protoporphyrin IX fluorescence in SCCs, therapeutic efficacy of ALA NP-mediated PDT, and immune responses were examined.Results: PLGA NPs enhanced protoporphyrin IX production in SCC. ALA PLGA NP-mediated topical PDT was more effective than free ALA of the same concentration in treating cutaneous SCC.Conclusion: PLGA NPs provide a promising strategy for delivering ALA in topical PDT of cutaneous SCC. Keywords: 5-aminolevulinic acid (ALA, polylactic-co-glycolic acid (PLGA, nanoparticles (NPs, cutaneous squamous cell carcinoma (SCC, photodynamic therapy (PDT, microneedling

  4. Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation

    OpenAIRE

    Akimichi Shibata; Shuhei Yada; Mitsuhiro Terakawa

    2016-01-01

    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 diffe...

  5. Fabrication of novel poly(lactic acid)/amorphous magnesium phosphate bionanocomposite fibers for tissue engineering applications via electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huan, E-mail: Huan.Zhou@Rockets.utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Nabiyouni, Maryam [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Lin, Boren [Department of Biological Sciences, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Department of Surgery (Dentistry), The University of Toledo, Toledo, OH (United States)

    2013-05-01

    Fibrous bionanocomposites consisting of amorphous magnesium phosphate (AMP) nanospheres and polylactic acid (PLA) were fabricated by electrospinning. There are two important signatures of this paper. First, AMP, as an alternative to well-known calcium phosphate (CaP) materials, is added to PLA as the second phase. To the best of our knowledge, it is the first attempt to fabricate magnesium phosphate (MgP)/biopolymer composite. This is made possible by our previously reported research on the successful synthesis of AMP nanospheres via microwave processing. Second, the sustained release of magnesium and phosphate ions from PLA matrix can stimulate a series of cell responses. The structure of the composites and their bone-like apatite-forming abilities in simulated body fluid (SBF) were examined. Additionally, the effects on the proliferation and differentiation of preosteoblast cells were evaluated by performing in vitro cell culture and monitoring markers such as Osteocalcin (OCN), Osteopontin (OPN), Alkaline phosphatase (ALP) and Collagen type-I (Col I) using real-time polymerase chain reaction (PCR). For better dispersion of AMP in the fibers, a surfactant, 12-hydroxysteric acid (HSA), as previously reported in the literature, was used. However, HSA significantly inhibited the proliferation and differentiation of preosteoblast cells, indicating the potential risk in using HSA in the combination of AMP or MgP in tissue engineering applications. - Highlights: ► Amorphous magnesium phosphate (AMP) nanospheres was synthesized. ► AMP/poly lactic acid (PLA) matrix was fabricated via electrospinning. ► AMP was found to be beneficial to MC3T3 preosteoblast cells proliferation. ► Surfactant 12-hydroxysteric acid (HSA) was toxic to preosteoblast cells.

  6. Fabrication of novel poly(lactic acid)/amorphous magnesium phosphate bionanocomposite fibers for tissue engineering applications via electrospinning

    International Nuclear Information System (INIS)

    Fibrous bionanocomposites consisting of amorphous magnesium phosphate (AMP) nanospheres and polylactic acid (PLA) were fabricated by electrospinning. There are two important signatures of this paper. First, AMP, as an alternative to well-known calcium phosphate (CaP) materials, is added to PLA as the second phase. To the best of our knowledge, it is the first attempt to fabricate magnesium phosphate (MgP)/biopolymer composite. This is made possible by our previously reported research on the successful synthesis of AMP nanospheres via microwave processing. Second, the sustained release of magnesium and phosphate ions from PLA matrix can stimulate a series of cell responses. The structure of the composites and their bone-like apatite-forming abilities in simulated body fluid (SBF) were examined. Additionally, the effects on the proliferation and differentiation of preosteoblast cells were evaluated by performing in vitro cell culture and monitoring markers such as Osteocalcin (OCN), Osteopontin (OPN), Alkaline phosphatase (ALP) and Collagen type-I (Col I) using real-time polymerase chain reaction (PCR). For better dispersion of AMP in the fibers, a surfactant, 12-hydroxysteric acid (HSA), as previously reported in the literature, was used. However, HSA significantly inhibited the proliferation and differentiation of preosteoblast cells, indicating the potential risk in using HSA in the combination of AMP or MgP in tissue engineering applications. - Highlights: ► Amorphous magnesium phosphate (AMP) nanospheres was synthesized. ► AMP/poly lactic acid (PLA) matrix was fabricated via electrospinning. ► AMP was found to be beneficial to MC3T3 preosteoblast cells proliferation. ► Surfactant 12-hydroxysteric acid (HSA) was toxic to preosteoblast cells

  7. Osteogenesis of human adipose-derived stem cells on hydroxyapatite-mineralized poly(lactic acid) nanofiber sheets

    International Nuclear Information System (INIS)

    Electrospun fiber sheets with various orientations (random, partially aligned, and aligned) and smooth and roughened casted membranes were prepared. Hydroxyapatite (HA) crystals were in situ formed on these material surfaces via immersion in 10 × simulated body fluid solution. The size and morphology of the resulting fibers were examined using scanning electron microscopy. The average diameter of the fibers ranged from 225 ± 25 to 1050 ± 150 nm depending on the electrospinning parameters. Biological experiment results show that human adipose-derived stem cells exhibit different adhesion and osteogenic differentiation on the three types of fiber. The cell proliferation and osteogenic differentiation were best on the aligned fibers. Similar results were found for phosphorylated focal adhesion kinase expression. Electrospun poly(lactic acid) aligned fibers mineralized with HA crystals provide a good environment for cell growth and osteogenic differentiation and thus have great potential in the tissue engineering field. - Highlights: • hADSCs show higher adhesion and proliferation on HA-precipitate electrospun fiber sheets than those of the control membranes. • HA-mineralized fiber groups greatly improve cell growth and increase FAK and p-FAK expressions. • HA-precipitate electrospun fiber sheets present higher ALP and OC activity through the study periods. • Electrospun PLA fiber mineralized with HA provides a good environment for cell growth and osteogenic differentiation. • A simple immersion of electrospun fibers in 10 × SBF are a potential matrix for bone tissue engineering

  8. Modification of polylactic acid surface using RF plasma discharge with sputter deposition of a hydroxyapatite target for increased biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Tverdokhlebov, S.I., E-mail: tverd@tpu.ru [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation); Bolbasov, E.N.; Shesterikov, E.V. [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation); Antonova, L.V.; Golovkin, A.S.; Matveeva, V.G. [Federal State Budgetary Institution Research Institute for Complex Issues of Cardiovascular Disease, 6 Sosnovy Blvd, Kemerovo 650002 (Russian Federation); Petlin, D.G.; Anissimov, Y.G. [Griffith University, School of Natural Sciences, Engineering Dr., Southport, QLD 4222 (Australia)

    2015-02-28

    Highlights: • The treatment by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering improves the biocompatibility of PLLA surface. • The treatment significantly increases the roughness of PLLA surface. • The formation of rough highly porous surface is due to the etching and crystallization processes on PLLA surface during treatment. • Maximum concentration of the ions from the sputtered target is achieved at 60 s of the plasma treatment. - Abstract: Surface modification of polylactic acid (PLLA) by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering was investigated. Increased biocompatibility was demonstrated using studies with bone marrow multipotent mesenchymal stromal cells. Atomic force microscopy demonstrates that the plasma treatment modifies the surface morphology of PLLA to produce rougher surface. Infrared spectroscopy and X-ray diffraction revealed that changes in the surface morphology are caused by the processes of PLLA crystallization. Fluorescent X-ray spectroscopy showed that the plasma treatment also changes the chemical composition of PLLA, enriching it with ions of the sputtered target: calcium, phosphorus and oxygen. It is hypothesized that these surface modifications increase biocompatibility of PLLA without increasing toxicity.

  9. Characterization of Active Packaging Films Made from Poly(Lactic Acid)/Poly(Trimethylene Carbonate) Incorporated with Oregano Essential Oil.

    Science.gov (United States)

    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

  10. Improved wettability and adhesion of polylactic acid/chitosan coating for bio-based multilayer film development

    Science.gov (United States)

    Gartner, Hunter; Li, Yana; Almenar, Eva

    2015-03-01

    The objective of this study was to investigate the effect of methyldiphenyl diisocyanate (MDI) concentration (0, 0.2, 1, 2, and 3%) on the wettability and adhesion of blend solutions of poly(lactic acid) (PLA) and chitosan (CS) when coated on PLA film for development of a bio-based multi-layer film suitable for food packaging and other applications. Characterization was carried out by attenuated total reflectance infrared spectrometry (ATR-FTIR), contact angle (θ), mechanical adhesion pull-off testing, and scanning electron microscopy (SEM). The θ of the PLA/CS blend shifted to a lower value (41-35°) with increasing MDI concentration showing that the surface tension was modified between the PLA/CS blend solution and PLA film and better wettability was achieved. The increase in MDI also resulted in an increased breaking strength (228-303 kPa) due to the increased H-bonding resulting from the more urethane groups formed within the PLA/CS blend as shown by ATR-FTIR. The improved adhesion was also shown by the increased number of physical entanglements observed by SEM. It can be concluded that MDI can be used to improve wettability and adhesion between PLA/CS coating and PLA film.

  11. Effect of Starch/Polylactic Acid Ratio on the Interdependence of Two-Phase and the Properties of Composites

    Institute of Scientific and Technical Information of China (English)

    ZUO Yingfeng; GU Jiyou; CAO Jun; WEI Shuangying; TAN Haiyan; ZHANG Yanhua

    2015-01-01

    Starch/polylactic acid (PLA) composites were prepared by melt extrusion, with corn starch and PLA as raw materials, glycerol as the plasticizer. Effects of starch/PLA ratio on the interdependence of two-phase and other properties of the composites were studied. The combination of results of TGA with SEM indicated that the interdependence between starch and PLA was increased gradually as the starch/PLA ratio reduced. DSC results showed that the glass transition temperature (Tg), melting temperature (Tm) and degree of crystallinity of PLA in composites were increased gradually, whereas the cold crystallization temperature (Tc) was gradually decreased as the starch/PLA ratio reduced. The rheological properties of composites were closely related with the interdependence of two-phase, with reducing starch/PLA proportion, the interdependence was increased, and then the strain for storage modulus was ifrstl reduced and then gradually increased. Frequency scanning showed that the storage modulus and complex viscosity were decreased with reducing starch content. As the starch/PLA ratio reduced, the matrix phase PLA was increased, so that the strength of composites was increased gradually, whereas water absorption rate was decreased gradually.

  12. Poly(lactic acid/thermoplastic starch sheets: effect of adipate esters on the morphological, mechanical and barrier properties

    Directory of Open Access Journals (Sweden)

    Marianne Ayumi Shirai

    2016-02-01

    Full Text Available Abstract Blends of poly(lactic acid (PLA and thermoplastic starch (TPS plasticized with adipate esters (diisodecyl adipate and diethyl adipate having different molecular weight were used to produce sheets. The calendering-extrusion process at a pilot scale was used, and the mechanical, barrier, and morphological characterization of the obtained materials were performed. The increase in the TPS content affected the mechanical properties of the sheets by increasing the elongation and decreasing the rigidity. TPS conferred a more hydrophilic character to the sheets, as observed from the water vapor permeability results. The sheets plasticized with diisodecyl adipate (DIA, having a higher molecular weight, had better mechanical and barrier properties than diethyl adipate (DEA plasticized sheets, indicating that DIA was more effective as plasticizer. Micrographs obtained by confocal laser microscopy and scanning electron microscopy showed different morphologies when different proportions of PLA and TPS were used (dispersed or co-continuous structures, which were strongly associated with the mechanical and barrier properties.

  13. Polypyrrole-coated electrospun poly(lactic acid) fibrous scaffold: effects of coating on electrical conductivity and neural cell growth.

    Science.gov (United States)

    Sudwilai, Thitima; Ng, Jun Jye; Boonkrai, Chatikorn; Israsena, Nipan; Chuangchote, Surawut; Supaphol, Pitt

    2014-01-01

    Neuronal activities play critical roles in both neurogenesis and neural regeneration. In that sense, electrically conductive and biocompatible biomaterial scaffolds can be applied in various applications of neural tissue engineering. In this study, we fabricated a novel biomaterial for neural tissue engineering applications by coating electrospun poly(lactic acid) (PLA) nanofibers with a conducting polymer, polypyrole (PPy), via admicellar polymerization. Optimal conditions for polymerization and preparation of PPy-coated electrospun PLA nanofibers were obtained by comparing results from scanning electron microscopy, X-ray photoelectron spectrometer, and surface conductivity tests. In vitro cell culture experiments showed that PPy-coated electrospun PLA fibrous scaffold is not toxic. The scaffold could support attachment and migration of neural progenitor cells. Neurons derived from progenitor exhibited long neurite outgrowth under electrical stimulation. Our study concluded that PPy-coated electrospun PLA fibers had a good biocompatibility with neural progenitor cells and may serve as a promising material for controlling progenitor cell behaviors and enhancing neural repair. PMID:24933469

  14. Poly(lactic acid) porous scaffold with calcium phosphate mineralized surface and bone marrow mesenchymal stem cell growth and differentiation

    International Nuclear Information System (INIS)

    This work aims to modify the surface of a poly(lactic acid) (PLA) porous scaffold with calcium phosphate (CaP) via a simple solution-based technique, and to evaluate the effects of this modification on the responses of rat bone marrow mesenchymal stem cells (rBMMSCs). Under appropriate modification conditions involving stepwise-treatments in the Ca-and-P supersaturated solution under gentle agitation, a thin, poorly crystallized CaP layer was deposited. The BMMSCs derived from adult rats were shown to adhere quite well to the CaP-coated scaffold, and to proliferate actively with culturing time, although some down-regulation was noted with regard to the unmodified PLA scaffold. The osteogenic differentiation of rBMMSCs was significantly higher on the CaP-modified scaffold than on the unmodified scaffold, as confirmed by alkaline phosphatase (ALP) activity. Moreover, the expression of genes associated with bone, including collagen type I, osteopontin and bone sialoprotein, was stimulated better on the CaP-modified PLA scaffold. Based on these results, the currently used CaP-treatment was deemed effective in stimulating the osteogenic development of rBMMSCs on the PLA-based scaffold, and the CaP-treated PLA scaffold may be useful for future bone tissue engineering.

  15. Preparation and investigation of polylactic acid, calcium carbonate and polyvinylalcohol nanofibrous scaffolds for osteogenic differentiation of mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    A. Doustgani

    2016-04-01

    Full Text Available Objective(s: In this study, the effect of electrospun fiber orientation on proliferation and differentiation of mesenchymal stem cells (MSCs was evaluated. Materials and Methods: Aligned and random nanocomposite nanofibrous scaffolds were electrospun from polylactic acid (PLA, poly (vinyl alcohol (PVA and calcium carbonate nanoparticles (nCaP. The surface morphology of prepared nanofibrous scaffolds with and without cell was examined using scanning electron microscopy. Mechanical properties of electrospun nanofibrous scaffolds were determined with a  universal testing machine. The in vitro properties of fabricated scaffolds was also investigated by the MTT assay and alkaline phosphatase activity (ALP.Results: The average fiber diameter for aligned and random nanofibers were 82 ± 12 nm and 124 ± 25 nm, respectively. The mechanical testing indicated the higher tensile strength and elastic modulus of aligned nanofibers. MTT and ALP results showed that alignment of nanofiber increased the osteogenic differentiation of stem cells.Conclusion: Aligned nanofibrous nanocomposite scaffolds of PLA/nCaP/PVA could be an excellent substrate for MSCs and represents a potential bone-filling material.

  16. Characterization of Active Packaging Films Made from Poly(Lactic Acid/Poly(Trimethylene Carbonate Incorporated with Oregano Essential Oil

    Directory of Open Access Journals (Sweden)

    Dong Liu

    2016-05-01

    Full Text Available 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.

  17. Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration.

    Science.gov (United States)

    Talal, Ahmed; McKay, I J; Tanner, K E; Hughes, Francis J

    2013-09-01

    The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre-absorbed with the growth factor. nHA-PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA-PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules. PMID:23832451

  18. Effect of silver nanoparticles and cellulose nanocrystals on electrospun poly(lactic) acid mats: morphology, thermal properties and mechanical behavior.

    Science.gov (United States)

    Cacciotti, Ilaria; Fortunati, Elena; Puglia, Debora; Kenny, Josè Maria; Nanni, Francesca

    2014-03-15

    The fabrication of ternary fibrous mats based on poly(lactic) acid (PLA), cellulose nanocrystals (CNCs, both pristine (p-CNCs) and modified with a commercial surfactant (s-CNCs)) and silver (Ag) nanoparticles by electrospinning is reported. Amounts of 1 and 5 wt.% were selected for Ag and CNCs, respectively. Neat PLA and binary PLA/Ag, PLA/p-CNCs and PLA/s-CNCs were produced as references. The CNCs and Ag influence on the microstructural, thermal and mechanical properties was investigated. The Ag and/or p-CNCs addition did not remarkably affect fiber morphology and average size dimension (between (468 ± 111) and (551 ± 122)nm), whereas the s-CNCs presence led to the deposition of a honeycomb-like network on a underneath layer of randomly oriented fibers. The efficiency of the surfactant use in promoting the CNC dispersion was demonstrated. A slight enhancement (e.g. around 25%, in terms of strength) of the mechanical properties of p-CNCs loaded fibers, particularly for PLA/Ag/p-CNCs, was revealed, whereas mats with s-CNCs showed a decrement (e.g. around 35-45%, in terms of strength), mainly imputable to the delamination between the upper honeycomb-like layer and the lower conventional fibrous mat. PMID:24528696

  19. New Composition of Maleic-Anhydride-Grafted Poly(Lactic Acid/Rice Husk with Methylenediphenyl Diisocyanate

    Directory of Open Access Journals (Sweden)

    Chi-Hui TSOU

    2014-12-01

    Full Text Available Maleic-anhydride-grafted poly(lactic acid (PLA-g-MAH was prepared and blended with rice husk (RH. Methylenediphenyl diisocyanate (MDI was used as the coupling agent for combining RH with PLA-g-MAH, which improved the poor interfacial adhesion between PLA and RH. Various PLA-g-MAH/RH blends, with and without MDI, were prepared by melt processing using a brabender. The effects that inclusion and distribution of MDI had on the mechanical properties and thermal behaviors of the composites were examined. The results showed that the PLAXRHYMDI specimens had the optimum tensile properties compared with the PLAXRHY, PLA-g-MAHXRHY, and PLA-g-MAHXRHYMDI specimens. The new method of combining MDI and MAH through grafting was expected to be an excellent strategy for mitigating the low functionality of commercial PLA. Possible reasons accounting for the interesting results on tensile strength and thermal properties of the specimens are proposed. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6034

  20. Structural Hierarchy and Polymorphic Transformation in Shear-Induced Shish-Kebab of Stereocomplex Poly(Lactic Acid).

    Science.gov (United States)

    Xie, Lan; Xu, Huan; Li, Zhong-Ming; Hakkarainen, Minna

    2016-05-01

    The realization of hierarchical shish-kebab structures for stereocomplex poly(lactic acid) (PLA) is achieved by the application of a shear flow (100 s(-1) for 1 s) mimicking what can be expected during polymer processing. Compared to the normal shearing scenarios, this transient and strong shear flow enables the creation of dense shish precursors in time- and energy-saving manner. The distribution of crystal form associated with the hierarchical structure is revealed by 2D Fourier transform infrared spectroscopy imaging, creating a unique visualization for both spatial resolution and polymorphism identification. Interestingly, in the shear stereocomplex chains are preferentially extended and crystallized as stable central cores with weak temperature dependence, whereas the development of lateral kebabs is defined by the distinct relation to the crystallization temperature. Below the melting point of homocrystals, both homo and stereocomplex crystallization are engaged in lamellar packing. Above that, exclusive stereocomplex crystals are organized into ordered lamellae. Combining the direct observations at multiscale, the ordered alignment of stereocomplex chains is recognized as the molecular origin of fibrillar extended chain bundles that constitute the central row-nuclei. The proposed hypothesis affords elucidation of shish-kebab formation and unique polymorphism in sheared stereocomplex PLA, which generates opportunities for engendering hierarchically structured PLA with improved performance. PMID:26987565

  1. Modification of polylactic acid surface using RF plasma discharge with sputter deposition of a hydroxyapatite target for increased biocompatibility

    International Nuclear Information System (INIS)

    Highlights: • The treatment by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering improves the biocompatibility of PLLA surface. • The treatment significantly increases the roughness of PLLA surface. • The formation of rough highly porous surface is due to the etching and crystallization processes on PLLA surface during treatment. • Maximum concentration of the ions from the sputtered target is achieved at 60 s of the plasma treatment. - Abstract: Surface modification of polylactic acid (PLLA) by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering was investigated. Increased biocompatibility was demonstrated using studies with bone marrow multipotent mesenchymal stromal cells. Atomic force microscopy demonstrates that the plasma treatment modifies the surface morphology of PLLA to produce rougher surface. Infrared spectroscopy and X-ray diffraction revealed that changes in the surface morphology are caused by the processes of PLLA crystallization. Fluorescent X-ray spectroscopy showed that the plasma treatment also changes the chemical composition of PLLA, enriching it with ions of the sputtered target: calcium, phosphorus and oxygen. It is hypothesized that these surface modifications increase biocompatibility of PLLA without increasing toxicity

  2. Investigation of liquid sensing mechanism of poly(lactic acid)/multi-walled carbon nanotube composite films

    International Nuclear Information System (INIS)

    The liquid sensing mechanism of melt-processed poly(lactic acid) (PLA)/multi-walled carbon nanotube (MWNT) composite films was investigated for the influence of MWNT loading, solubility parameters of solvents used, solvent transport behaviours, resultant electrical resistance changes, as well as crystallization of the PLA matrix. The diffusion, sorption and permeation coefficients of neat PLA and the composites were estimated, indicating that MWNT network structures block solvent molecules from penetrating into the polymer matrix. Solvent-induced crystallization of the polymer matrix was observed. Isothermally crystallized composites showed reduced resistances, a significant decrease of sorbed solvent content and a reduction of the resulting resistance changes on the solvent contact. In the context with sensing results on MWNT mats, it was proposed that the liquid sensing mechanism of PLA/MWNT composites consists of the overall electrical resistance changes caused by the structural variation of the conductive MWNT network in the polymer matrix and additional interactions between the MWNT and solvent molecules

  3. Osteogenesis of human adipose-derived stem cells on hydroxyapatite-mineralized poly(lactic acid) nanofiber sheets

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Fu-Chen [Department of Health Developing and Health Marketing, Kainan University, Taiwan (China); Lin, Chi-Chang, E-mail: chichang31@thu.edu.tw [Department of Chemical and Materials Engineering, Tunghai University, Taiwan (China); Lai, Wen-Fu T., E-mail: Laitw@tmu.edu.tw [Graduate Institute of Clinical Medicine, Taipei Medical University, Taiwan (China)

    2014-12-01

    Electrospun fiber sheets with various orientations (random, partially aligned, and aligned) and smooth and roughened casted membranes were prepared. Hydroxyapatite (HA) crystals were in situ formed on these material surfaces via immersion in 10 × simulated body fluid solution. The size and morphology of the resulting fibers were examined using scanning electron microscopy. The average diameter of the fibers ranged from 225 ± 25 to 1050 ± 150 nm depending on the electrospinning parameters. Biological experiment results show that human adipose-derived stem cells exhibit different adhesion and osteogenic differentiation on the three types of fiber. The cell proliferation and osteogenic differentiation were best on the aligned fibers. Similar results were found for phosphorylated focal adhesion kinase expression. Electrospun poly(lactic acid) aligned fibers mineralized with HA crystals provide a good environment for cell growth and osteogenic differentiation and thus have great potential in the tissue engineering field. - Highlights: • hADSCs show higher adhesion and proliferation on HA-precipitate electrospun fiber sheets than those of the control membranes. • HA-mineralized fiber groups greatly improve cell growth and increase FAK and p-FAK expressions. • HA-precipitate electrospun fiber sheets present higher ALP and OC activity through the study periods. • Electrospun PLA fiber mineralized with HA provides a good environment for cell growth and osteogenic differentiation. • A simple immersion of electrospun fibers in 10 × SBF are a potential matrix for bone tissue engineering.

  4. Effect of immersion in simulated body environment on mechanical properties of twist-oriented poly(lactic acid) screws

    Science.gov (United States)

    Sakaguchi, Masato; Kobayashi, Satoshi; composite engineering lab Collaboration

    Poly(lactic acid) (PLA) has been applied to bone fixation devices, since it has high biocompatibility. In order to apply PLA device to a higher loaded part, mechanical properties of PLA have been improved by uniaxial drawing. However, mechanical properties along the other loading direction than the drawing direction such as torsion were not improved. Therefore, surgeon should be carefully conducted not to brake the reinforced PLA screw when tightening. In this study, screw is focused on as a bone fixation device. In order to improve torsional strength of a PLA screw, twist-orientation method was developed. PLA screw is prepared through a series of routes including casting, extrusion drawing, twist-orientation and forging. This screw was immersed in the phosphate buffered solution for 0, 8, 16 and 24 weeks, then shear strength, orientation function, crystallinity and molecular weight were measured. As a result, twist-orientation improves the initial torsional strength of PLA screw without the decrease in initial shear strength. In addition, the shear strength on twist-oriented screw is equivalent that of non-twist oriented screw during immersion until 24 weeks. This result shown that the twist-orientation does not decrease shear strength after immersion.

  5. Synthesis and characterization of bionanocomposites with tunable properties from poly(lactic acid) and acetylated microfibrillated cellulose.

    Science.gov (United States)

    Tingaut, Philippe; Zimmermann, Tanja; Lopez-Suevos, Francisco

    2010-02-01

    In the present study, novel bionanocomposite materials with tunable properties were successfully prepared using a poly(lactic acid) (PLA) matrix and acetylated microfibrillated cellulose (MFC) as reinforcing agent. The acetylation of MFC was confirmed by FTIR and (13)C CP-MAS NMR spectroscopies. The grafting of acetyl moieties on the cellulose surface not only prevented MFC hornification upon drying but also dramatically improved redispersibility of the powdered nanofibers in chloroform, a PLA solvent of low polarity. Moreover, we demonstrate that the properties of the resulting PLA nanocomposites could be tailored by adjusting both the acetyl content (Ac%) and the amount of MFC. These nanomaterials showed improved filler dispersion, higher thermal stability, and reduced hygroscopicity with respect to those prepared with unmodified MFC. Dynamic mechanical analysis (DMA) highlighted the reinforcing potential of both the unmodified and the acetylated MFC on the viscoelastic properties of the neat PLA. But more interesting, an increase in the PLA glass transition temperature was detected when using the 8.5% acetylated MFC at 17 wt %, indicating an improved compatibility at the fiber-matrix interface. These findings suggest that the final properties of nanocomposite materials can be controlled by adjusting the %Ac of MFC. PMID:20025270

  6. Synthesis of graphene oxide grafted poly(lactic acid) with palladium nanoparticles and its application to serotonin sensing

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hyoung Soon; You, Jung-Min; Jeong, Haesang; Jeon, Seungwon, E-mail: swjeon3380@naver.com

    2013-11-01

    Graphene oxide (GO) has treated with methylene diphenyl diisocyanate (MDI) and subsequent 1,4-butanediol (BD) to create an anchoring OH site on the surface of GO (GO-MDI-OH). The OH groups of GO-MDI-OH were the initiators of the polymerization of poly(lactic acid) (PLA). The subsequent GO-g-PLA was synthesized by the polymerization reaction in the presence of GO-MDI-OH and PLA. The synthesized materials were characterized via {sup 1}H-NMR, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal analysis (differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA)). The surface morphologies and degree of dispersions at G-g-PLA-metals were observed using a field emission scanning electron microscope (FE-SEM) and a transmission electron microscopy (TEM). The electrical conductivity of G-g-PLA-Pd was largely enhanced compared with those of GO and GO-g-PLA. G-g-PLA-Pd was used for the electrochemical detection of serotonin. Electrocatalytic activities were verified from the cyclic voltammetry (CV) and amperometric response in a 0.1 M phosphate buffer solution (PBS). A significantly higher concentration range (0.1–100.0 μM) and a lower detection limit (8.0 × 10{sup −8} M, where s/n = 3) were found at the G-g-PLA-Pd modified glassy carbon electrode (GCE).

  7. Mandibular bone repair by implantation of rhBMP-2 in a slow release carrier of polylactic acid--an experimental study in rats.

    OpenAIRE

    Schliephake, Henning; Weich, Herbert A.; Dullin, Christian; Gruber, Rudolf; Frahse, Sarah

    2008-01-01

    The aim of the present study was to test the hypothesis that human recombinant bone morphogenic protein 2 (rhBMP-2) implanted in a slow release carrier of polylactic acid (PLA) can repair a non-healing defect in the rat mandible and maintain the thickness of an augmented volume. p-DL-lactic acid discs were produced and loaded with 48 and 96 microg rhBMP-2 and inserted into non-healing defects of the mandible of 45 Wistar rats. Fifteen rats received implants with 96 microg rhBMP-2 (Group 2), 4...

  8. Encapsulation of gallic acid/cyclodextrin inclusion complex in electrospun polylactic acid nanofibers: Release behavior and antioxidant activity of gallic acid.

    Science.gov (United States)

    Aytac, Zeynep; Kusku, Semran Ipek; Durgun, Engin; Uyar, Tamer

    2016-06-01

    Cyclodextrin-inclusion complexes (CD-ICs) possess great prominence in food and pharmaceutical industries due to their enhanced ability for stabilization of active compounds during processing, storage and usage. Here, CD-IC of gallic acid (GA) with hydroxypropyl-beta-cyclodextrin (GA/HPβCD-IC) was prepared and then incorporated into polylactic acid (PLA) nanofibers (PLA/GA/HPβCD-IC-NF) using electrospinning technique to observe the effect of CD-ICs in the release behavior of GA into three different mediums (water, 10% ethanol and 95% ethanol). The GA incorporated PLA nanofibers (PLA/GA-NFs) were served as control. Phase solubility studies showed an enhanced solubility of GA with increasing amount of HPβCD. The detailed characterization techniques (XRD, TGA and (1)H-NMR) confirmed the formation of inclusion complex between GA and HPβCD. Computational modeling studies indicated that the GA made an efficient complex with HPβCD at 1:1 either in vacuum or aqueous system. SEM images revealed the bead-free and uniform morphology of PLA/GA/HPβCD-IC-NF. The release studies of GA from PLA/GA/HPβCD-IC-NF and PLA/GA-NF were carried out in water, 10% ethanol and 95% ethanol, and the findings revealed that PLA/GA/HPβCD-IC-NF has released much more amount of GA in water and 10% ethanol system when compared to PLA/GA-NF. In addition, GA was released slowly from PLA/GA/HPβCD-IC-NF into 95% ethanol when compared to PLA/GA-NF. It was also observed that electrospinning process had no negative effect on the antioxidant activity of GA when GA was incorporated in PLA nanofibers. PMID:27040215

  9. Influence of oxidation on fulvic acids composition and biodegradability.

    Science.gov (United States)

    Kozyatnyk, Ivan; Świetlik, Joanna; Raczyk-Stanisławiak, Ursula; Dąbrowska, Agata; Klymenko, Nataliya; Nawrocki, Jacek

    2013-08-01

    Oxidation is well-known process of transforming natural organic matter during the treatment of drinking water. Chlorine, ozone, and chlorine dioxide are common oxidants used in water treatment technologies for this purpose. We studied the influence of different doses of these oxidants on by-products formation and changes in biodegradable dissolved organic carbon (BDOC) and molecular weight distribution (MWD) of fulvic acids (FA) with different BDOC content. Chlorination did not significantly change the MWD of FA and disinfection by-products formation. However, higher molecular weight compounds, than those in the initial FA, were formed. It could be a result of chlorine substitution into the FA structure. Chlorine dioxide oxidized FA stronger than chlorine. During ozonation of FA, we found the highest increase of BDOD due to the formation of a high amount of organic acids and aldehydes. FA molecules were transformed into a more biodegradable form. Ozonation is the most preferable process among those observed for pre-treatment of FA before biofiltration. PMID:23746389

  10. Poly lactic acid based biodegradable stents and functionalization techniques: brief review

    OpenAIRE

    Rebelo, Rita; Vila, Nívea Taís; Rana, Sohel; Fangueiro, Raúl

    2015-01-01

    Commercial stents, especially metallic ones, present several disadvantages, and this gives rise to the necessity of producing or coating stents with different materials, like natural polymers, in order to improve their biocompatibility and minimize the disadvantages of metallic ones. This review paper discusses some applications of natural-based polymers in stents, namely polylactic acid (PLA) for stent development and chitosan for biocompatible coatings of stents . Furthermore...

  11. Improved wettability and adhesion of polylactic acid/chitosan coating for bio-based multilayer film development

    Energy Technology Data Exchange (ETDEWEB)

    Gartner, Hunter [School of Packaging, Michigan State University, East Lansing, Michigan (United States); Li, Yana [Mechanical Engineering College, Wuhan Polytechnic University (China); Almenar, Eva, E-mail: ealmenar@msu.edu [School of Packaging, Michigan State University, East Lansing, Michigan (United States)

    2015-03-30

    Graphical abstract: - Highlights: • Surface tension between PLA/CS blend solution and PLA film modified by MDI. • Better wettability between PLA/CS blend solution and PLA film by increasing MDI. • Increased breaking strength by increasing MDI due to the increased H-bonding. • Increased number of physical entanglements between PLA/CS coating and PLA film. • Development of a suitable bio-based multilayer film for food packaging applications. - Abstract: The objective of this study was to investigate the effect of methyldiphenyl diisocyanate (MDI) concentration (0, 0.2, 1, 2, and 3%) on the wettability and adhesion of blend solutions of poly(lactic acid) (PLA) and chitosan (CS) when coated on PLA film for development of a bio-based multi-layer film suitable for food packaging and other applications. Characterization was carried out by attenuated total reflectance infrared spectrometry (ATR-FTIR), contact angle (θ), mechanical adhesion pull-off testing, and scanning electron microscopy (SEM). The θ of the PLA/CS blend shifted to a lower value (41–35°) with increasing MDI concentration showing that the surface tension was modified between the PLA/CS blend solution and PLA film and better wettability was achieved. The increase in MDI also resulted in an increased breaking strength (228–303 kPa) due to the increased H-bonding resulting from the more urethane groups formed within the PLA/CS blend as shown by ATR-FTIR. The improved adhesion was also shown by the increased number of physical entanglements observed by SEM. It can be concluded that MDI can be used to improve wettability and adhesion between PLA/CS coating and PLA film.

  12. Improved wettability and adhesion of polylactic acid/chitosan coating for bio-based multilayer film development

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Surface tension between PLA/CS blend solution and PLA film modified by MDI. • Better wettability between PLA/CS blend solution and PLA film by increasing MDI. • Increased breaking strength by increasing MDI due to the increased H-bonding. • Increased number of physical entanglements between PLA/CS coating and PLA film. • Development of a suitable bio-based multilayer film for food packaging applications. - Abstract: The objective of this study was to investigate the effect of methyldiphenyl diisocyanate (MDI) concentration (0, 0.2, 1, 2, and 3%) on the wettability and adhesion of blend solutions of poly(lactic acid) (PLA) and chitosan (CS) when coated on PLA film for development of a bio-based multi-layer film suitable for food packaging and other applications. Characterization was carried out by attenuated total reflectance infrared spectrometry (ATR-FTIR), contact angle (θ), mechanical adhesion pull-off testing, and scanning electron microscopy (SEM). The θ of the PLA/CS blend shifted to a lower value (41–35°) with increasing MDI concentration showing that the surface tension was modified between the PLA/CS blend solution and PLA film and better wettability was achieved. The increase in MDI also resulted in an increased breaking strength (228–303 kPa) due to the increased H-bonding resulting from the more urethane groups formed within the PLA/CS blend as shown by ATR-FTIR. The improved adhesion was also shown by the increased number of physical entanglements observed by SEM. It can be concluded that MDI can be used to improve wettability and adhesion between PLA/CS coating and PLA film

  13. Magnetic Cellulose Nanocrystal Based Anisotropic Polylactic Acid Nanocomposite Films: Influence on Electrical, Magnetic, Thermal, and Mechanical Properties.

    Science.gov (United States)

    Dhar, Prodyut; Kumar, Amit; Katiyar, Vimal

    2016-07-20

    This paper reports a single-step co-precipitation method for the fabrication of magnetic cellulose nanocrystals (MGCNCs) with high iron oxide nanoparticle content (∼51 wt % loading) adsorbed onto cellulose nanocrystals (CNCs). X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopic studies confirmed that the hydroxyl groups on the surface of CNCs (derived from the bamboo pulp) acted as anchor points for the adsorption of Fe3O4 nanoparticles. The fabricated MGCNCs have a high magnetic moment, which is utilized to orient the magnetoresponsive nanofillers in parallel or perpendicular orientations inside the polylactic acid (PLA) matrix. Magnetic-field-assisted directional alignment of MGCNCs led to the incorporation of anisotropic mechanical, thermal, and electrical properties in the fabricated PLA-MGCNC nanocomposites. Thermomechanical studies showed significant improvement in the elastic modulus and glass-transition temperature for the magnetically oriented samples. Differential scanning calorimetry (DSC) and XRD studies confirmed that the alignment of MGCNCs led to the improvement in the percentage crystallinity and, with the absence of the cold-crystallization phenomenon, finds a potential application in polymer processing in the presence of magnetic field. The tensile strength and percentage elongation for the parallel-oriented samples improved by ∼70 and 240%, respectively, and for perpendicular-oriented samples, by ∼58 and 172%, respectively, in comparison to the unoriented samples. Furthermore, its anisotropically induced electrical and magnetic properties are desirable for fabricating self-biased electronics products. We also demonstrate that the fabricated anisotropic PLA-MGCNC nanocomposites could be laminated into films with the incorporation of directionally tunable mechanical properties. Therefore, the current study provides a novel noninvasive approach of orienting nontoxic bioderived CNCs in the presence of low

  14. A Novel Hierarchical Structured Poly(lactic acid/Titania Fibrous Membrane with Excellent Antibacterial Activity and Air Filtration Performance

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    2016-01-01

    Full Text Available Hybrid poly(lactic acid/titania (PLA/TiO2 fibrous membranes exhibiting excellent air filtration performance and good antibacterial activity were prepared via the electrospinning technique. By varying the composition of the precursor solutions and the relative humidity, the morphologies of PLA/TiO2 fibers, including the nanopores and nanometer-scale protrusions on the surface of the fibers, could be regulated. The distribution of nanopores and TiO2 nanoparticles on the surface of PLA/TiO2 fibers was investigated. Nitrogen adsorption-desorption analysis revealed that nanopores and nanometer-scale protrusions play an important role in improving the specific surface area and nanopore volume of the relevant PLA/TiO2 fibrous membrane. Filtration performance tests conducted by measuring the penetration of sodium chloride aerosol particles with a 260 nm mass median diameter indicated that fibers with a high surface roughness, large specific surface area, and large nanopore volume greatly improved the particle capture efficiency and facilitated the penetration of airflow. Furthermore, the introduction of TiO2 nanoparticles endows the relevant fibrous membrane with antibacterial properties. The as-prepared PLA/TiO2 fibrous membrane loaded with 1.75 wt% TiO2 nanoparticles formed at a relative humidity of 45% exhibited a high filtration efficiency (99.996% and a relatively low pressure drop (128.7 Pa, as well as a high antibacterial activity of 99.5%.

  15. Development of poly(lactic acid) nanostructured membranes for the controlled delivery of progesterone to livestock animals

    International Nuclear Information System (INIS)

    Solution blow spinning (SBS) is a novel technology feasible to produce nanostructured polymeric membranes loaded with active agents. In the present study, nanofibrous mats of poly(lactic acid) (PLA) loaded with progesterone (P4) were produced by SBS at different P4 concentrations. The spun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The in vitro releasing of P4 was evaluated using high-performance liquid chromatography (HPLC). Interactions between progesterone and PLA were confirmed by rheological measurements of the PLA/P4 solutions and in the spun mats by microscopy (SEM), thermal (DSC) and spectral (FTIR) analyses. SEM micrographs provided evidences of a smooth and homogeneous structure for nanostructured membranes without progesterone crystals on fiber surface. FTIR spectroscopy indicated miscibility and interaction between the ester of PLA and the ketone groups of the P4 in the nanofibers. X-ray analysis indicated that the size of PLA crystallites increased with progesterone content. Finally, by in vitro release experiments it was possible to observe that the progesterone releasing follows nearly first-order kinetics, probably due to the diffusion of hormone into PLA nanofibers. - Highlights: ► Nanofibers of PLA loading with progesterone were prepared via solution blow spinning. ► Their morphology, FTIR, and XRD and DSC characterization were analyzed. ► Fibers of PLA/progesterone with diameters from 280 to 440 nm were obtained. ► The effect of progesterone content in fiber properties was studied.

  16. Inactivation of Listeria monocytogenes in skim milk and liquid egg white by antimicrobial bottle coating with polylactic acid and nisin.

    Science.gov (United States)

    Jin, Tony

    2010-03-01

    This study was to develop an antimicrobial bottle coating method to reduce the risk of outbreaks of human listeriosis caused by contaminated liquid foods. Liquid egg white and skim milk were inoculated with Listeria monocytogenes Scott A and stored in glass jars that were coated with a mixture of polylactic acid (PLA) polymer and nisin. The efficacy of PLA per nisin coating in inactivating L. monocytogenes was investigated at 10 and 4 degrees C. The pathogen grew well in skim milk without PLA/nisin coating treatments, reaching 8 log CFU/mL after 10 d and then remained constant up to 42 d at 10 degrees C. The growth of Listeria at 4 degrees C was slower than that at 10 degrees C, taking 21 d to obtain 8 log CFU/mL. At both storage temperatures, the PLA coating with 250 mg nisin completely inactivated the cells of L. monocytogenes after 3 d and throughout the 42-d storage period. In liquid egg white, Listeria cells in control and PLA coating without nisin samples declined 1 log CFU/mL during the first 6 d at 10 degrees C and during 28 d at 4 degrees C, and then increased to 8 or 5.5 log CFU/mL. The treatment of PLA coating with 250 mg nisin rapidly reduced the cell numbers of Listeria in liquid egg white to undetectable levels after 1 d, then remained undetectable throughout the 48 d storage period at 10 degrees C and the 70 d storage period at 4 degrees C. These data suggested that the PLA/nisin coating treatments effectively inactivated the cells of L. monocytogenes in liquid egg white and skim milk samples at both 10 and 4 degrees C. This study demonstrated the commercial potential of applying the antimicrobial bottle coating method to milk, liquid eggs, and possibly other fluid products. PMID:20492246

  17. GX1-conjugated poly(lactic acid nanoparticles encapsulating Endostar for improved in vivo anticolorectal cancer treatment

    Directory of Open Access Journals (Sweden)

    Du Y

    2015-05-01

    Full Text Available Yang Du,1,* Qian Zhang,1,* Lijia Jing,2 Xiaolong Liang,2 Chongwei Chi,1 Yaqian Li,1 Xin Yang,1 Zhifei Dai,2 Jie Tian1 1Key Laboratory of Molecular Imaging, The State Key Laboratory of Management and Control for Complex Systems, Institute of Automation, Chinese Academy of Sciences, Beijing, People’s Republic of China; 2Department of Biomedical Engineering, College of Engineering, Peking University, Beijing People’s Republic of China *These authors contributed equally to this work Abstract: Tumor angiogenesis plays a key role in tumor growth and metastasis; thus, targeting tumor-associated angiogenesis is an important goal in cancer therapy. However, the efficient delivery of drugs to tumors remains a key issue in antiangiogenesis therapy. GX1, a peptide identified by phage-display technology, is a novel tumor vasculature endothelium-specific ligand and possesses great potential as a targeted vector and antiangiogenic agent in the diagnosis and treatment of human cancers. Endostar, a novel recombinant human endostatin, has been shown to inhibit tumor angiogenesis. In this study, we developed a theranostic agent composed of GX1-conjugated poly(lactic acid nanoparticles encapsulating Endostar (GPENs and labeled with the near-infrared dye IRDye 800CW to improve colorectal tumor targeting and treatment efficacy in vivo. The in vivo fluorescence molecular imaging data showed that GPENs (IRDye 800CW more specifically targeted tumors than free IRDye 800CW in colorectal tumor-bearing mice. Moreover, the antitumor efficacy was evaluated by bioluminescence imaging and immunohistology, revealing that GPENs possessed improved antitumor efficacy on subcutaneous colorectal xenografts compared to other treatment groups. Thus, our study showed that GPENs, a novel GX1 peptide guided form of nanoscale Endostar, can be used as a theranostic agent to facilitate more efficient targeted therapy and enable real-time monitoring of therapeutic efficacy in vivo

  18. Development of poly(lactic acid) nanostructured membranes for the controlled delivery of progesterone to livestock animals

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Juliano Elvis [Laboratorio Nacional de Nanotecnologia para o Agronegocio (LNNA), Embrapa Instrumentacao (CNPDIA), Rua XV de Novembro, 1452, Centro, 13.560, 970 Sao Carlos, SP (Brazil); Medeiros, Eliton Souto [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia de Materiais (DEMAT), Cidade Universitaria, 58.051-900, Joao Pessoa, PB (Brazil); Cardozo, Lucio; Voll, Fernando [Departamento de Engenharia Quimica, Universidade Estadual de Maringa (UEM), 87.020, 900 Maringa, PR (Brazil); Madureira, Ed Hoffmann [Departamento de Reproducao Animal, Faculdade de Medicina Veterinaria e Zootecnia (FMVZ), Universidade de Sao Paulo (USP), Pirassununga-SP (Brazil); Mattoso, Luiz Henrique Capparelli, E-mail: mattoso@cnpdia.embrapa.br [Laboratorio Nacional de Nanotecnologia para o Agronegocio (LNNA), Embrapa Instrumentacao (CNPDIA), Rua XV de Novembro, 1452, Centro, 13.560, 970 Sao Carlos, SP (Brazil); Assis, Odilio Benedito Garrido [Laboratorio Nacional de Nanotecnologia para o Agronegocio (LNNA), Embrapa Instrumentacao (CNPDIA), Rua XV de Novembro, 1452, Centro, 13.560, 970 Sao Carlos, SP (Brazil)

    2013-03-01

    Solution blow spinning (SBS) is a novel technology feasible to produce nanostructured polymeric membranes loaded with active agents. In the present study, nanofibrous mats of poly(lactic acid) (PLA) loaded with progesterone (P4) were produced by SBS at different P4 concentrations. The spun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The in vitro releasing of P4 was evaluated using high-performance liquid chromatography (HPLC). Interactions between progesterone and PLA were confirmed by rheological measurements of the PLA/P4 solutions and in the spun mats by microscopy (SEM), thermal (DSC) and spectral (FTIR) analyses. SEM micrographs provided evidences of a smooth and homogeneous structure for nanostructured membranes without progesterone crystals on fiber surface. FTIR spectroscopy indicated miscibility and interaction between the ester of PLA and the ketone groups of the P4 in the nanofibers. X-ray analysis indicated that the size of PLA crystallites increased with progesterone content. Finally, by in vitro release experiments it was possible to observe that the progesterone releasing follows nearly first-order kinetics, probably due to the diffusion of hormone into PLA nanofibers. - Highlights: Black-Right-Pointing-Pointer Nanofibers of PLA loading with progesterone were prepared via solution blow spinning. Black-Right-Pointing-Pointer Their morphology, FTIR, and XRD and DSC characterization were analyzed. Black-Right-Pointing-Pointer Fibers of PLA/progesterone with diameters from 280 to 440 nm were obtained. Black-Right-Pointing-Pointer The effect of progesterone content in fiber properties was studied.

  19. Polylactic acid/zinc oxide biocomposite films for food packaging application.

    Science.gov (United States)

    Marra, Antonella; Silvestre, Clara; Duraccio, Donatella; Cimmino, Sossio

    2016-07-01

    Although PLA is much more expensive than polyolefins, such as PP and PE, there is a great interest to propose PLA based material as alternative films for food packaging being PLA derivable from natural source, compostable and biodegradable. For this purpose the research has the task to investigate and propose PLA materials with enhanced properties to be effectively and efficiently alternative to polyolefin films for food packaging application. In this contribution, biocomposite films of PLA with 1, 3 and 5wt% of ZnO have been investigated to determine mechanical, barrier and antimicrobial (against Escherichia coli) properties. It is found that the biocomposite films are characterized by a good dispersion of the ZnO particles in PLA matrix, although no previous treatment was performed on ZnO particles, such as silanization, to decrease its incompatibility with the polymer. The biocomposite films have shown good mechanical properties, decrease of permeability to CO2 and O2, and only a slight increase to water vapour. Particularly important is that, for the biocomposite with 5wt% of ZnO, the % Reduction for E. Coli test reached the value of 99.99 already after 24h. PMID:27012896

  20. Preparation of Surfactant-free Core-Shell Poly(lactic acid) / Calcium Phosphate Hybrid Particles and Their Drug Release Characteristics

    International Nuclear Information System (INIS)

    We propose surfactant-free core-shell poly(lactic acid) (PLA) / calcium phosphate (CaP) hybrid particles as drug delivery carriers. These particles were prepared by biomineralization process using ultrasonic irradiation, and their drug release profiles were investigated. Drug release rate was earlier when particles were prepared by PLA with a low molecular weight, and/or by Ca(CH3COO)2 and (NH4)2HPO4. Also, these were shown good protein adsorption. This work indicates that these particles have sustained-release ability without initial burst and can do targeting capability by biomolecule conjugation.

  1. Polylactic acid based materials and nanostructured multilayers for cardiovascular devices and wound healing

    OpenAIRE

    Carmagnola, Irene

    2013-01-01

    i. Poly(L-lactic acid), which is the current gold standard to fabricate bioresorbable stents, was modified by blending, with the aim to prepare a material with lower degradation time and improved mechanical properties. Binary blends of poly(L-lactic) acid (PLLA1: 80428 Da and PLLA2: 201790 Da) and poly(lactide-co-glycolide) (PLGA1) (LA:GA = 50:50 mol:mol; 32030 Da) with various compositions (100/0; 75/25: 50/50; 25/75; 0/100 wt./wt.) were prepared by solution casting. SEM analysis showed a bi...

  2. Nanoamphiphilic Chitosan Dispersed Poly(lactic acid) Bionanocomposite Films with Improved Thermal, Mechanical, and Gas Barrier Properties.

    Science.gov (United States)

    Pal, Akhilesh Kumar; Katiyar, Vimal

    2016-08-01

    This article demonstrates the synthesis of lactic acid oligomer-grafted-chitosan (OLLA-g-CH), a nanoamphiphilic molecule, by in situ condensation polymerization and its effective use as a nanofiller for improvement in multiple properties of poly(lactic acid) (PLA) films, essential for stringent food packaging applications. Fourier transform infrared spectroscopy (FTIR) analysis shows the presence of amide-ester bond at 1539 cm(-1), which confirms the structural grafting of OLLA chains with chitosan molecules. This nanoamphiphilic OLLA-g-CH molecule act as surfactant containing hydrophilic chitosan head and hydrophobic OLLA tails with average size in the range of ∼2-4 nm. Prepared PLA/OLLA-g-CH bionanocomposite films appear with uniform dispersion of nanoamphiphilic OLLA-g-CH molecules with self-assembled micelles having size as low as ∼20 nm and as high as ∼150 nm with core-shell morphology in PLA matrix. This nanofiller is found very effective toward significant reduction in oxygen permeability (OP) by ∼10-fold due to the reduction in solubility of oxygen molecules and improvement in crystal nucleation density due to availability of nanonucleating sites. Ultimate tensile strength (UTS) of PLA/OLLA-g-CH bionanocomposite films are relatively comparable to that of PLA, however, elongation at break is improved significantly. The onset of thermal degradation of PLA/(OLLA-g-CH) films is also found comparable to that of PLA film. The glass transition temperature (Tg) of bionanocomposites is decreased by more than 18 °C with increase in OLLA-g-CH loading, which indicates the improved plasticization characteristics of PLA matrix. The crystallization kinetics suggest nonthree dimensional truncated spherical structures, which is controlled by the combination of thermal and athermal instantaneous nucleations. POM analysis suggested that the spherulite growth of PLA is improved significantly with the addition of OLLA-g-CH. The reduction in Tg of PLA with improvement

  3. Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe.

    Science.gov (United States)

    Hack, Norman; Reinwand, Christian; Abbt-Braun, Gudrun; Horn, Harald; Frimmel, Fritz H

    2015-12-01

    Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200...600 μm, porosity ε=0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol)=0 after t=6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest. PMID:26529301

  4. Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe

    Science.gov (United States)

    Hack, Norman; Reinwand, Christian; Abbt-Braun, Gudrun; Horn, Harald; Frimmel, Fritz H.

    2015-12-01

    Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp = 200…600 μm, porosity ε = 0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol) = 0 after t = 6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest.

  5. Thermal characterization of the composites based on poly(lactic acid)

    OpenAIRE

    Srebrenkoska, Vineta; Bogoeva-Gaceva, Gordana

    2011-01-01

    In this study, rice-hulls-filled poly (lactic acid) (PLA) composites were prepared through addition of 5 wt. % PLA-grafted-MA (CA) for enhancement of adhesion between polymer matrix and natural filler. The composites containing 30% wt. rice hulls (RH) were prepared by compression molding. For the composites, the thermal properties were analyzed and compared to those of commonly used thermoplastic based-polymer, polypropylene (PP) containing the same reinforcement. Thermal stability of composi...

  6. A biomimetic multilayer nanofiber fabric fabricated by electrospinning and textile technology from polylactic acid and Tussah silk fibroin as a scaffold for bone tissue engineering.

    Science.gov (United States)

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

    2016-10-01

    To engineer bone tissue, a scaffold with good biological properties should be provided to approximate the hierarchical structure of collagen fibrils in natural bone. In this study, we fabricated a novel scaffold consisting of multilayer nanofiber fabrics (MLNFFs) by weaving nanofiber yarns of polylactic acid (PLA) and Tussah silk fibroin (TSF). The yarns were fabricated by electrospinning, and we found that spinnability, as well as the mechanical properties of the resulting scaffold, was determined by the ratio between polylactic acid and Tussah silk fibroin. In particular, a 9:1 mixture can be spun continuously into nanofiber yarns with narrow diameter distribution and good mechanical properties. Accordingly, woven scaffolds based on this mixture had excellent mechanical properties, with Young's modulus 417.65MPa and tensile strength 180.36MPa. For nonwoven scaffolds fabricated from the same materials, the Young's modulus and tensile strength were 2- and 4-fold lower, respectively. Woven scaffolds also supported adhesion and proliferation of mouse mesenchymal stem cells, and promoted biomineralization via alkaline phosphatase and mineral deposition. Finally, the scaffolds significantly enhanced the formation of new bone in damaged femoral condyle in rabbits. Thus, the scaffolds are potentially suitable for bone tissue engineering because of biomimetic architecture, excellent mechanical properties, and good biocompatibility. PMID:27287159

  7. Effect of surface modification of poly(lactic acid) by low-pressure ammonia plasma on adsorption of human serum albumin

    International Nuclear Information System (INIS)

    Highlights: • Poly(lactic acid) (PLA) films were treated by low-pressure ammonia plasma. • Human serum albumin (HSA) attachment on the treated PLA was reduced. • The treated PLA films were characterized. • Hydrophilicity enhancement due to polar groups introduced was the reason. • Reduced HSA adhesion could promote cell attachment on PLA for biomedicine. - Abstract: The final goal of the study was to promote understanding of mechanisms involved in cell attachment on biomedical polymer poly(lactic acid) (PLA). As the cell attachment on the material surface was preceded by blood protein adsorption which would critically affect subsequent cell adhesion, for the clinic application purpose, human serum albumin (HSA) was used in the investigation on its adsorption on PLA, which was however treated by low-pressure ammonia (NH3) plasma. The NH3-plasma-treated PLA was found to adsorb less HSA than the untreated PLA. The PLA was characterized using various techniques such as atomic force microscopy, contact angle and surface energy analysis and x-ray photoelectron spectroscopy. All of the characterization results indicated that due to NH3-plasma-induced polar groups the PLA enhanced its hydrophilicity which in turn inhibited the HSA adsorption. The decreased HSA adsorption would consequently increase the cell attachment because of the cell adhesion barrier reduced

  8. Effect of surface modification of poly(lactic acid) by low-pressure ammonia plasma on adsorption of human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayuthaya Road, Bangkok 10400 (Thailand); Boonyawan, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayuthaya Road, Bangkok 10400 (Thailand); Chaiwong, C., E-mail: cchwng@gmail.com [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayuthaya Road, Bangkok 10400 (Thailand)

    2014-08-15

    Highlights: • Poly(lactic acid) (PLA) films were treated by low-pressure ammonia plasma. • Human serum albumin (HSA) attachment on the treated PLA was reduced. • The treated PLA films were characterized. • Hydrophilicity enhancement due to polar groups introduced was the reason. • Reduced HSA adhesion could promote cell attachment on PLA for biomedicine. - Abstract: The final goal of the study was to promote understanding of mechanisms involved in cell attachment on biomedical polymer poly(lactic acid) (PLA). As the cell attachment on the material surface was preceded by blood protein adsorption which would critically affect subsequent cell adhesion, for the clinic application purpose, human serum albumin (HSA) was used in the investigation on its adsorption on PLA, which was however treated by low-pressure ammonia (NH{sub 3}) plasma. The NH{sub 3}-plasma-treated PLA was found to adsorb less HSA than the untreated PLA. The PLA was characterized using various techniques such as atomic force microscopy, contact angle and surface energy analysis and x-ray photoelectron spectroscopy. All of the characterization results indicated that due to NH{sub 3}-plasma-induced polar groups the PLA enhanced its hydrophilicity which in turn inhibited the HSA adsorption. The decreased HSA adsorption would consequently increase the cell attachment because of the cell adhesion barrier reduced.

  9. Effect of different plasticizers on the properties of bio-based thermoplastic elastomer containing poly(lactic acid and natural rubber

    Directory of Open Access Journals (Sweden)

    V. Tanrattanakul

    2014-06-01

    Full Text Available Bio-based thermoplastic elastomers (TPE containing natural rubber and poly(lactic acid were prepared by melt blending in an internal mixer. The blend ratio was 60% of natural rubber and 40% of poly(lactic acid. Dynamic vulcanization of natural rubber was performed with the sulfur system. The 2 mm – thick sheet samples were prepared by compression molding. The objective of this study was to investigate the effect of plasticization of PLA on the mechanical and physical properties of the derived TPE. Four plasticizers were selected: tributyl acetyl citrate (TBAC, tributyl citrate (TBC, glycerol triacetate (GTA, and triethyl-2-acetyl citrate (TEAC. The investigated properties were the tensile properties, tear strength, thermal ageing and ozone resistance, hardness, resilience, tension set and compression set. All plasticizers increased the strain at break. TBAC and TBC increased the stress at break. All plasticizers decreased the tear strength, hardness and resilience, and slightly changed the tension and compression set. TBAC seemed to be the best plasticizer for the TPE. The presence of 4 pph (parts per hundred resin of plasticizer provided the highest strength and tensile toughness and the strain at break increased with the increasing plasticizer content. The plasticizers decreased the Tg and Tcc of the PLA and did not affect the degree of crystallinity of PLA in the TPE.

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

    Science.gov (United States)

    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.

  11. A novel basalt fiber-reinforced polylactic acid composite for hard tissue repair

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xi; Li Yan; Gu Ning, E-mail: guning@seu.edu.c [Jiangsu Laboratory for Biomaterials and Devices, State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096 (China)

    2010-08-01

    A basalt fiber (BF) was, for the first time, introduced into a poly(l-lactic acid) (PLLA) matrix as innovative reinforcement to fabricate composite materials for hard tissue repair. Firstly, BF/PLLA composites and pure PLLA were produced by the methods of solution blending and freeze drying. The results showed that basalt fibers can be uniformly dispersed in the PLLA matrix and significantly improve the mechanical properties and hydrophilicity of the PLLA matrix. The presence of basalt fibers may retard the polymer degradation rate and neutralize the acid degradation from PLLA. Osteoblasts were cultured in vitro to evaluate the cytocompatibility of the composite. An MTT assay revealed that osteoblasts proliferated well for 7 days and there was little difference found in their viability on both PLLA and BF/PLLA films, which was consistent with the alkaline phosphatase (ALP) activity results. A fluorescent staining observation showed that osteoblasts grew well on the composites. SEM images displayed that osteoblasts tended to grow along the fiber axis. The formation of mineralized nodules was observed on the films by Alizarin red S staining. These results suggest that the presence of basalt fibers does not noticeably affect osteoblastic behavior and the designed composites are osteoblast compatible. It is concluded that basalt fibers, as reinforcing fibers, may have promising applications in hard tissue repair.

  12. A novel basalt fiber-reinforced polylactic acid composite for hard tissue repair

    International Nuclear Information System (INIS)

    A basalt fiber (BF) was, for the first time, introduced into a poly(l-lactic acid) (PLLA) matrix as innovative reinforcement to fabricate composite materials for hard tissue repair. Firstly, BF/PLLA composites and pure PLLA were produced by the methods of solution blending and freeze drying. The results showed that basalt fibers can be uniformly dispersed in the PLLA matrix and significantly improve the mechanical properties and hydrophilicity of the PLLA matrix. The presence of basalt fibers may retard the polymer degradation rate and neutralize the acid degradation from PLLA. Osteoblasts were cultured in vitro to evaluate the cytocompatibility of the composite. An MTT assay revealed that osteoblasts proliferated well for 7 days and there was little difference found in their viability on both PLLA and BF/PLLA films, which was consistent with the alkaline phosphatase (ALP) activity results. A fluorescent staining observation showed that osteoblasts grew well on the composites. SEM images displayed that osteoblasts tended to grow along the fiber axis. The formation of mineralized nodules was observed on the films by Alizarin red S staining. These results suggest that the presence of basalt fibers does not noticeably affect osteoblastic behavior and the designed composites are osteoblast compatible. It is concluded that basalt fibers, as reinforcing fibers, may have promising applications in hard tissue repair.

  13. A novel basalt fiber-reinforced polylactic acid composite for hard tissue repair.

    Science.gov (United States)

    Chen, Xi; Li, Yan; Gu, Ning

    2010-08-01

    A basalt fiber (BF) was, for the first time, introduced into a poly(l-lactic acid) (PLLA) matrix as innovative reinforcement to fabricate composite materials for hard tissue repair. Firstly, BF/PLLA composites and pure PLLA were produced by the methods of solution blending and freeze drying. The results showed that basalt fibers can be uniformly dispersed in the PLLA matrix and significantly improve the mechanical properties and hydrophilicity of the PLLA matrix. The presence of basalt fibers may retard the polymer degradation rate and neutralize the acid degradation from PLLA. Osteoblasts were cultured in vitro to evaluate the cytocompatibility of the composite. An MTT assay revealed that osteoblasts proliferated well for 7 days and there was little difference found in their viability on both PLLA and BF/PLLA films, which was consistent with the alkaline phosphatase (ALP) activity results. A fluorescent staining observation showed that osteoblasts grew well on the composites. SEM images displayed that osteoblasts tended to grow along the fiber axis. The formation of mineralized nodules was observed on the films by Alizarin red S staining. These results suggest that the presence of basalt fibers does not noticeably affect osteoblastic behavior and the designed composites are osteoblast compatible. It is concluded that basalt fibers, as reinforcing fibers, may have promising applications in hard tissue repair. PMID:20683132

  14. Nucleating effect of exfoliated graphite nanoplatelets on poly(hydroxybutyrate) and poly(lactic acid) and their nanocomposites properties

    Science.gov (United States)

    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

  15. Morphology and thermal degradation study of poly(lactic acid)/synthetic mica composites; Estudo da morfologia e da degradacao termica de compositos de poli(acido latico)/mica sintetica organofilica

    Energy Technology Data Exchange (ETDEWEB)

    Souza, D.H.S.; Dias, M.L., E-mail: diegosaboya@ima.ufrj.b [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano

    2010-07-01

    Poly(lactic acid) (PLA)/synthetic mica composites has been little studied in the literature. In this work, an organophilic synthetic mica was used to prepare PLA nanocomposites. The composites were obtained at an internal mixer containing 3, 5, 7 and 10 wt% of mica. The materials were analyzed by x-ray diffraction, thermogravimetric analysis and gel permeation chromatography. (author)

  16. Synthesis, characterization and biocompatibility evaluation of hydroxyapatite - gelatin polyLactic acid ternary nanocomposite

    Directory of Open Access Journals (Sweden)

    Z. Nabipour

    2016-04-01

    Full Text Available Objective(s: The current study reports the production and biocompatibility evaluation of a ternary nanocomposite consisting of HA, PLA, and gelatin for biomedical application.Materials and Methods: Hydroxyapatite nanopowder (HA: Ca10(PO46(OH2 was produced by burning the bovine cortical bone within the temperature range of 350-450 oC followed by heating in an oven at 800. Synthesis of the ternary nanocomposite was carried out in two steps: synthesis of gelatin-hydroxyapatite binary nanocomposite and addition of poly lactic acid with different percentages to the resulting composition. The crystal structure was determined by X-ray diffraction (XRD, while major elements and impurities of hydroxyapatite were identified by elemental analysis of X-ray fluorescence (XRF. Functional groups were determined by Fourier transform infrared spectroscopy (FTIR. Morphology and size of the nanocomposites were evaluated using field emission scanning electron microscope (FE-SEM.Biocompatibility of nanocomposites was investigated by MTT assay. Results: XRD patterns verified the ideal crystal structure of the hydroxyapatite, which indicated an appropriate synthesis process and absence of disturbing phases. Results of FTIR analysis determined the polymers’ functional groups, specified formation of the polymers on the hydroxyapatite surface, and verified synthesis of nHA/PLA/Gel composite. FESEM images also indicated the homogeneous structure of the composite in the range of 50 nanometers. MTT assay results confirmed the biocompatibility of nanocomposite samples.Conclusion: This study suggested that the ternary nanocomposite of nHA/PLA/Gel can be a good candidate for biomedical application such as drug delivery systems, but for evaluation of its potential in hard tissue replacement, mechanical tests should be performed.

  17. Transparent nanocellulosic multilayer thin films on polylactic acid with tunable gas barrier properties.

    Science.gov (United States)

    Aulin, Christian; Karabulut, Erdem; Tran, Amy; Wågberg, Lars; Lindström, Tom

    2013-08-14

    The layer-by-layer (LbL) deposition method was used for the build-up of alternating layers of nanofibrillated cellulose (NFC) or carboxymethyl cellulose (CMC) with a branched, cationic polyelectrolyte, polyethyleneimine (PEI) on flexible poly (lactic acid) (PLA) substrates. With this procedure, optically transparent nanocellulosic films with tunable gas barrier properties were formed. 50 layer pairs of PEI/NFC and PEI/CMC deposited on PLA have oxygen permeabilities of 0.34 and 0.71 cm(3)·μm/m(2)·day·kPa at 23 °C and 50% relative humidity, respectively, which is in the same range as polyvinyl alcohol and ethylene vinyl alcohol. The oxygen permeability of these multilayer nanocomposites outperforms those of pure NFC films prepared by solvent-casting. The nanocellulosic LbL assemblies on PLA substrates was in detailed characterized using a quartz crystal microbalance with dissipation (QCM-D). Atomic force microscopy (AFM) reveals large structural differences between the PEI/NFC and the PEI/CMC assemblies, with the PEI/NFC assembly showing a highly entangled network of nanofibrils, whereas the PEI/CMC surfaces lacked structural features. Scanning electron microscopy images showed a nearly perfect uniformity of the nanocellulosic coatings on PLA, and light transmittance results revealed remarkable transparency of the LbL-coated PLA films. The present work demonstrates the first ever LbL films based on high aspect ratio, water-dispersible nanofibrillated cellulose, and water-soluble carboxymethyl cellulose polymers that can be used as multifunctional films and coatings with tailorable properties, such as gas barriers and transparency. Owing to its flexibility, transparency and high-performance gas barrier properties, these thin film assemblies are promising candidates for several large-scale applications, including flexible electronics and renewable packaging. PMID:23834391

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

    International Nuclear Information System (INIS)

    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. (paper)

  19. Macroporous Biodegradable Cryogels of Synthetic Poly(α-amino acids).

    Science.gov (United States)

    Sedlačík, Tomáš; Proks, Vladimír; Šlouf, Miroslav; Dušková-Smrčková, Miroslava; Studenovská, Hana; Rypáček, František

    2015-11-01

    We present an investigation of the preparation of highly porous hydrogels based on biodegradable synthetic poly(α-amino acid) as potential tissue engineering scaffolds. Covalently cross-linked gels with permanent pores were formed under cryogenic conditions by free-radical copolymerization of poly[N(5)-(2-hydroxyethyl)-L-glutamine-stat-N(5)-(2-methacryloyl-oxy-ethyl)-L-glutamine] (PHEG-MA) with 2-hydrohyethyl methacrylate (HEMA) and, optionally, N-propargyl acrylamide (PrAAm) as minor comonomers. The morphology of the cryogels showed interconnected polyhedral or laminar pores. The volume content of communicating water-filled pores was >90%. The storage moduli of the swollen cryogels were in the range of 1-6 kPa, even when the water content was >95%. The enzymatic degradation of a cryogel corresponded to the decrease in its storage modulus during incubation with papain, a model enzyme with specificity analogous to wound-healing enzymes. It was shown that cryogels with incorporated alkyne groups can easily be modified with short synthetic peptides using azide-alkyne cycloaddition "click" chemistry, thus providing porous hydrogel scaffolds with biomimetic features. PMID:26474357

  20. Fade to Green: A Biodegradable Stack of Microbial Fuel Cells.

    Science.gov (United States)

    Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Stinchcombe, Andrew; Walter, X Alexis; Greenman, John; Ieropoulos, Ioannis

    2015-08-24

    The focus of this study is the development of biodegradable microbial fuel cells (MFCs) able to produce useful power. Reactors with an 8 mL chamber volume were designed using all biodegradable products: polylactic acid for the frames, natural rubber as the cation-exchange membrane and egg-based, open-to-air cathodes coated with a lanolin gas diffusion layer. Forty MFCs were operated in various configurations. When fed with urine, the biodegradable stack was able to power appliances and was still operational after six months. One useful application for this truly sustainable MFC technology includes onboard power supplies for biodegradable robotic systems. After operation in remote ecological locations, these could degrade harmlessly into the surroundings to leave no trace when the mission is complete. PMID:26212495

  1. The embolization effect of tanshinone II A-polylactic acid/glycolic acid microspheres on the hepatic artery in experimental rabbits

    International Nuclear Information System (INIS)

    Objective: To observe the embolization effect of tanshinone II A-polylactic acid/glycolic acid microspheres (PLGA) on the hepatic artery in experimental rabbits. Methods: Under DSA guidance, hepatic catheterization and angiography was performed in 24 New Zealand white rabbits. Via the catheter tanshinone II A-PLGA microspheres was injected into the hepatic arteries. Each time at 10 minutes and on the 1 st, 3 rd, 7 th, 14 th, 21 st, 30 th and 42 nd day after the treatment, every three rabbits were randomly selected for the re-examination with angiography to observe the embolization state of the hepatic arteries, then the animals were sacrificed and the liver, heart, spleen, lung kidney and stomach were removed and sent for pathologic exam. Simultaneously, the functional tests of liver and kidney as well as the routine blood tests were made. The results were evaluated. Results: The peripheral micro-vessels of the hepatic artery vanished away at 10 minutes after embolization, and they remained un-visualized till the 30th day after embolization. On the 42nd day after embolization the peripheral micro-vessels of the hepatic artery could be visualized again. Pathologically,signs of inflammation and necrosis appeared in the occluded areas. Blood biochemical examination showed that there was a transient elevation of white blood cells after the procedure, which fell to normal level on the 7th day (P > 0.05). Both AST and ALT reached their peaks on the 3rd day, then they decreased gradually and returned to normal on the 7th day (P > 0.05). Conclusion: Tanshinone II A-PLGA microspheres have better embolization effect on the hepatic arteries, this effect lasts for 30 to 42 days. Therefore, tanshinone II A-PLGA microsphere is an ideal embolization agent for the treatment of neoplasm. (authors)

  2. 生态友好材料聚乳酸的合成研究进展%Recent Advances in Synthesis of Eco-friendly Polymers Based on Polylactic Acid

    Institute of Scientific and Technical Information of China (English)

    黄伟; 李弘; 张全兴

    2012-01-01

    Synthesis and application of polylactic acid (PLA), a kind of eco-friendly polymers possessing excellent biocompatibility and biodegradability, has recently attracted greatly attention. PLA is manufactured by two methods, i. e. polycondensation and ring-opening. Commercially the catalysts used for the synthesis of PLA are stannous compounds as stannous chloride dehydrate, and stannous octoate. Research revealed that the stannous compounds are cytotoxic that has aroused concern about the bio-safety of the materials based on PLA and its use in humans. Key advances in synthesis of PLA were reviewed.%聚乳酸(PLA)是一种具有高度生物相容性、生物可降解性的环境友好型材料,其合成方法及应用研究日益受到关注。聚乳酸的合成主要有两种方法:缩聚和开环。商品化聚乳酸合成中所使用的催化剂主要为锡类化合物,例如二水合氯化亚锡和辛酸亚锡。研究表明锡类化合物具有一定的生理毒性,因而引起了人们对聚乳酸材料的生物安全性以及其在人体中使用的关注。本文综述了近年在生物降解性聚乳酸类材料的合成方面的重要研究进展。

  3. Production and characterization of thermoplastic cassava starch, functionalized poly(lactic acid), and their reactive compatibilized blends

    Science.gov (United States)

    Detyothin, Sukeewan

    Cassava starch was blended with glycerol using a co-rotating twin-screw extruder (TSE). Thermoplastic cassava starch (TPCS) at a ratio of 70/30 by weight of cassava/glycerol was selected and further blended with other polymers. TPCS sheets made from compression molding had low tensile strength (0.45 +/- 0.05 MPa) and Young's modulus (1.24 +/- 0.58 MPa), but moderate elongation at break (83.0 +/- 0.18.6%), medium level of oxygen permeability, and high water vapor permeability with a very high rate of water absorption. TPCS was blended with poly(lactic acid) (PLA) at various ratios by using a TSE. The blend resins exhibited good properties such as increased thermal stability (Tmax) and crystallinity of PLA, and improved water sensitivity and processability of TPCS. PLA and TPCS exhibited a high interfacial tension between the two phases of 7.9 mJ·m -2, indicating the formation of an incompatible, immiscible blend. SEM micrographs showed a non-homogeneous distribution of TPCS droplets in the PLA continuous phase. TEM micrographs of the blend films made by cast-film extrusion showed coalescence of the TPCS droplets in the PLA continuous phase of the blend, indicating that the compatibility between the polymer pair needs to be improved. A response surface methodology (RSM) design was used to analyze the effects of maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox or L101) contents, and TSE screw speed on the degree of grafted MA and number average molecular weight (Mn) of functionalized PLA (PLA-g-MA), a reactive compatibilizer. PLA-g- MA made by reactive extrusion had an array of colors depending on the content of L101 and MA used. New FTIR peaks suggested that MA was grafted onto the PLA backbone and oligomeric MA may occur. Increasing L101 increased the degree of grafting and decreased Mn, but the Mn of the PLA-g-MA's produced with a high amount of L101 was stable during storage. MA exhibited an optimum concentration for maximizing the

  4. The toxicity of rifampicin polylactic acid nanoparticles against Mycobacterium bovis BCG and human macrophage THP-1 cell line

    Science.gov (United States)

    Erokhina, M.; Rybalkina, E.; Barsegyan, G.; Onishchenko, G.; Lepekha, L.

    2015-11-01

    Tuberculosis is rapidly becoming a major health problem. The rise in tuberculosis incidence stimulates efforts to develop more effective delivery systems for the existing antituberculous drugs while decreasing the side effects. The nanotechnology may provide novel drug delivery tools allowing controlled drug release. Rifampicin is one of the main antituberculous drugs, characterized by high toxicity, and Poly (L-lactic acid) (PLLA) is a biodegradable polymer used for the preparation of encapsulated drugs. The aim of our work was to evaluate the toxicity of rifampicin-PLLA nanoparticles against Mycobacterium bovis BCG using human macrophage THP-1 cell line. Our data demonstrate that rifampicin-PLLA is effective against M. bovis BCG in the infected macrophages. The drug is inducing the dysfunction of mitochondria and apoptosis in the macrophages and is acting as a potential substrate of Pgp thereby modulating cell chemosensitivity. The severity of the toxic effects of the rifampicin-PLLA nanoparticles is increasing in a dose-dependent manner. We suggest that free rifampicin induces death of M. bovis BCG after PLLA degradation and diffusion from phago-lysosomes to cytoplasm causing mitochondria dysfunction and affecting the Pgp activity.

  5. Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation

    Science.gov (United States)

    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.

  6. Effects of SEBS-g-MAH on the properties of injection moulded poly(lactic acid/nano-calcium carbonate composites

    Directory of Open Access Journals (Sweden)

    W. S. Chow

    2012-06-01

    Full Text Available Poly(lactic acid/nano-precipitated calcium carbonate (PLA/NPCC composites toughened with maleated styrene-ethylene/butylene-styrene (SEBS-g-MAH were prepared by melt-compounding on a co-rotating twin-screw extruder followed by injection moulding. The mechanical properties of the PLA nanocomposites were characterized by tensile, flexural and impact tests, while their morphology were investigated using transmission electron microscopy (TEM. The thermal properties of the composites were examined with differential scanning calorimeter (DSC and thermogravimetric analyzer (TGA. The elongation at break and impact strength of the PLA/NPCC nanocomposites increased significantly after addition of SEBS-g-MAH. Both nano-dispersed NPCC and small NPCC clusters were found in PLA matrix. Also, some SEBS-g-MAH encapsulated NPCC can be observed. Thermal stability of PLA/NPCC was enhanced prominently by the addition of SEBS-g-MAH.

  7. Polylactic acid-nanocrystalline carbonated hydroxyapatite (PLA-cHAP) composite: preparation and surface topographical structuring with direct laser writing (DLW)

    CERN Document Server

    Garskaite, Edita; Drienovsky, Marian; Krajcovic, Jozef; Cicka, Roman; Palcut, Marian; Jonusauskas, Linas; Malinauskas, Mangirdas; Stankeviciute, Zivile; Kareiva, Aivaras

    2016-01-01

    The fabrication of polylactic acid (PLA)-carbonated hydroxyapatite (cHAP) composite material from synthesised phase pure nano-cHAP and melted PLA by mechanical mixing at 220-235{\\deg}C has been developed in this study. Topographical structuring of PLA-cHAP composite surfaces was performed by direct laser writing (DLW). Microstructured surfaces and the apatite distribution within the composite and formed grooves were evaluated by optical and scanning electron microscopies. The influence of the dopant concentration as well as the laser power and translation velocity on the composite surface morphology is discussed. The synthesis of carbonated hydroxyapatite (cHAP) nanocrystalline powders via wet chemistry approach from calcium acetate and diammonium hydrogen phosphate precursors together with crosslinking and complexing agents of polyethylene glycol, poly(vinyl alcohol) and triethanolamine is also reported. Thermal decomposition of the gels and formation of nanocrystalline cHAP were evaluated by thermal analysi...

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Warangkhana, Phromma; Rathanawan, Magaraphan, E-mail: rathanawan.k@chula.ac.th [Chulalongkorn University, Petroleum and Petrochemical College - Bangkok (Thailand); Jana Sadhan, C., E-mail: janas@uakron.edu [The University of Akron, Department of Polymer Engineering, Ohio (United States)

    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.

  10. Monolithic calcium phosphate/poly(lactic acid) composite versus calcium phosphate-coated poly(lactic acid) for support of osteogenic differentiation of human mesenchymal stromal cells.

    Science.gov (United States)

    Tahmasebi Birgani, Zeinab; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-03-01

    Calcium phosphates (CaPs), extensively used synthetic bone graft substitutes, are often combined with other materials with the aim to overcome issues related to poor mechanical properties of most CaP ceramics. Thin ceramic coatings on metallic implants and polymer-ceramic composites are examples of such hybrid materials. Both the properties of the CaP used and the method of incorporation into a hybrid structure are determinant for the bioactivity of the final construct. In the present study, a monolithic composite comprising nano-sized CaP and poly(lactic acid) (PLA) and a CaP-coated PLA were comparatively investigated for their ability to support proliferation and osteogenic differentiation of bone marrow-derived human mesenchymal stromal cells (hMSCs). Both, the PLA/CaP composite, produced using physical mixing and extrusion and CaP-coated PLA, resulting from a biomimetic coating process at near-physiological conditions, supported proliferation of hMSCs with highest rates at PLA/CaP composite. Enzymatic alkaline phosphatase activity as well as the mRNA expression of bone morphogenetic protein-2, osteopontin and osteocalcin were higher on the composite and coated polymer as compared to the PLA control, while no significant differences were observed between the two methods of combining CaP and PLA. The results of this study confirmed the importance of CaP in osteogenic differentiation while the exact properties and the method of incorporation into the hybrid material played a less prominent role. PMID:26787486

  11. Biodegradable microcontainers as an oral drug delivery system for poorly soluble drugs.

    OpenAIRE

    Nielsen, Line Hagner; Nagstrup, Johan; Keller, Stephan Sylvest; Gordon, Sarah; Østergaard, Jesper; Rades, Thomas; Müllertz, Anette; Boisen, Anja

    2013-01-01

    PURPOSE: To fabricate microcontainers in biodegradable polylactic acid (PLLA) polymer films using hot embossing, and investigate the application of fabricated microcontainers as an oral drug delivery system for a poorly soluble drug.METHODS: For fabrication of the PLLA microcontainers, a film of PLLA was produced by spin coating. The film was heated above the polymer glass transition temperature (Tg), and a stamp was forced into the film. Following cooling of the film the stamp was removed, e...

  12. Biodegradation of New Polymer Foundry Binders for the Example of the Composition Polyacrylic Acid/Starch

    Directory of Open Access Journals (Sweden)

    Beata Grabowska

    2011-04-01

    Full Text Available The investigations on the biodegradation process pathway of the new polymer binders for the example of water soluble compositionpolyacrylic acid/starch are presented in the hereby paper. Degradation was carried out in water environment and in a soil. Thedetermination of the total oxidation biodegradation in water environment was performed under laboratory conditions in accordance with the static water test system (Zahn-Wellens method, in which the mixture undergoing biodecomposition contained inorganic nutrient,activated sludge and the polymer composition, as the only carbon and energy source. The biodecomposition progress of the polymercomposition sample in water environment was estimated on the basis of the chemical oxygen demand (COD measurements and thedetermination the biodegradation degree, Rt, during the test. These investigations indicated that the composition polyacrylic acid/starchconstitutes the fully biodegradable material in water environment. The biodegradation degree Rt determined in the last 29th day of the test duration achieved 65%, which means that the investigated polymer composition can be considered to be fully biodegradable.During the 6 months biodegradation process of the cross-linked sample of the polymer composition in a garden soil several analysis ofsurface and structural changes, resulting from the sample decomposition, were performed. Those were: thermal analyses (TG-DSC,structural analyses (Raman spectroscopy and microscopic analyses (optical microscopy, AFM.

  13. Poly (lactic acid) organoclay nano composites for paper coating applications

    OpenAIRE

    Tatcha Sonjui; Nantana Jiratumnukul

    2014-01-01

    Poly(lactic acid) or PLA is a well-known biodegradable polymer derived from renewable resources such as corn strach, tapioca strach, and sugar cane. PLA is the most extensively utilized biodegradable polyester with potential to replace conventional petrochemical-based polymers. However, PLA has some drawbacks, such as brittleness and poor gas barrier properties. Nano composite polymers have experience and increasing interest due to their characteristics, especially in mechanical a...

  14. PREPARATION AND PROPERTIES OF POLY (LACTIC ACID-CO-GLYCOL TEREPHTHALIC ACID) COPOLYESTER

    Institute of Scientific and Technical Information of China (English)

    GAO Cuili; JI Quan; KONG Qingshan; XIA Yanzhi

    2006-01-01

    To obtain a kind of biodegradable polymer material with satisfactory properties, a new biodegradable copolyester poly(lactic acid-co-glycol terephthalate) (PETA), was synthesized from three monomers of lactic acid, glycol and terephthalic acid. The resulting copolyesters, PETA, were characterized by FT-IR, 1H-NMR, DSC, TGA and by the ways of weight loss rate to characterize their biodegradability. The findings in this work indicated that, the TmS and TdS of copolyesters PETA increased with increasing contents of the terephthalic acid units. From the biodegradation tests in natural soil, boiling water, acid buffer solution and alkali buffer solution, it was shown that the biodegradability of copolyesters PETA decreased with increasing contents of the terephthalic acid units.

  15. Continuous biodegradation of sulfanilic acid in a multi-stage packed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Salazar-Huerta, A.; Velazquez-Garcia, A.; Cobos-Vasconcelos, D. de los.; Juarez-Ramirez, C.; Ruiz-Ordaz, N.; Galindez-Mayer, J.

    2009-07-01

    Sulfanilic acid SA is an aromatic amine derived from the azo-bond cleavage of several textile dyes. Recalcitrance and toxicity of this amine is high, and with frequency it could be found as an aquatic contaminant; thus biodegradation process for its removal are justified. Although the SA molecule contains carbon, nitrogen and sulphur, its C:N:S proportion is unbalanced for microbial growth in a biodegradation process; thus nutrient complementation should be necessary for its complete removal. (Author)

  16. 聚乳酸薄膜对西兰花的保鲜效果分析%Effect of Polylactic Acid Film Packaging on Preservation of Broccoli

    Institute of Scientific and Technical Information of China (English)

    李伟; 张一珠; 付正义; 张伟阳; 程树军

    2016-01-01

    Polylactic acid (PLA) film was applied to preserve broccoli with polyethylene (PE) film packaging and without packaging as controls. The effect of PLA film on preservation of broccoli quality was investigated by periodically recording quality changes during storage at a constant temperature of (20 ± 3) ℃. The results showed that the vitamin C and chlorophyll contents of broccoli were declined, while the relative conductivity and peroxidase (POD) activity were increased during storage under all three packaging conditions. The broccoli packaged in PLA film showed minimum changes. From the above results it is clear that PLA film can preserve broccoli quality obviously and effectively prolong its shelf life at normal temperature.%用聚乳酸(polylactic acid,PLA)薄膜包装西兰花,以聚乙烯(polyethylene,PE)薄膜包装和无膜包装为对照组,在(20±3)℃条件下对西兰花的相关指标进行定期测定,研究PLA薄膜对西兰花的保鲜效果。结果表明:在PLA薄膜、PE薄膜和无膜包装贮藏过程中,西兰花的VC、叶绿素含量均呈下降趋势,且前者含量明显高于后两者,而相对电导率、过氧化物酶活性均呈上升趋势,前者明显低于后两者。可见,PLA薄膜包装处理对常温条件下的西兰花有明显的保鲜效果,能有效地延长西兰花的常温货架期。

  17. Synthesis of Bio-Based Poly(lactic acid-co-10-hydroxy decanoate Copolymers with High Thermal Stability and Ductility

    Directory of Open Access Journals (Sweden)

    Dongjian Shi

    2015-03-01

    Full Text Available Novel bio-based aliphatic copolyesters, poly(lactic acid-co-10-hydroxy decanoate (P(LA-co-HDA, PLH, were successfully synthesized from lactic acid (LA and 10-hydroxycapric acid (HDA by a thermal polycondensation process, in the presence of p-toluenesulfonic acid (p-TSA and SnCl2·2H2O as co-catalyst. The copolymer structure was characterized by Fourier transform infrared (FTIR and proton nuclear magnetic resonance (1H NMR. The weight average molecular weights (Mw of PLH, from gel permeation chromatography (GPC measurements, were controlled from 18,500 to 37,900 by changing the molar ratios of LA and HDA. Thermogravimetric analysis (TGA results showed that PLH had excellent thermal stability, and the decomposition temperature at the maximum rate was above 280 °C. The glass transition temperature (Tg and melting temperature (Tm of PLH decreased continuously with increasing the HDA composition by differential scanning calorimetry (DSC measurements. PLH showed high ductility, and the breaking elongation increased significantly by the increment of the HDA composition. Moreover, the PLH copolymer could degrade in buffer solution. The cell adhesion results showed that PLH had good biocompatibility with NIH/3T3 cells. The bio-based PLH copolymers have potential applications as thermoplastics, elastomers or impact modifiers in the biomedical, industrial and agricultural fields.

  18. Degradation and osteogenic potential of a novel poly(lactic acid/nano-sized β-tricalcium phosphate scaffold

    Directory of Open Access Journals (Sweden)

    Cao L

    2012-11-01

    % nβ-TCP as a promising scaffold for bone regeneration.Keywords: poly (lactic acid, β-tricalcium phosphate, biodegradation, porous scaffold, bone regeneration

  19. Biodegradation of poly(lactic acid) and poly(butylene succinate-co-adipate) by Paenibacillus amylolyticus strain TB-13

    OpenAIRE

    Teeraphatpornchai, Teerawat

    2003-01-01

    Polymer materials developed during the last 80 years are generally resistant to microbial attack, a property that is now currently regarded as a shortcoming concerning solid waste management. As a source of alternative environmental friendly materials, the synthesis of degradable polymers is becoming of considerable interest.Recently, increasing iterest has been devoted to understanding the degradation mechanisms of polymers in the environment. A number of synthetic polymers have been referre...

  20. 以马铃薯残渣为原料的端羟基乳酸预聚物的制备%Synthesis of Hydroxyl Terminated Prepolymer of Polylactic Acid Using Potato Waste as Raw Materials

    Institute of Scientific and Technical Information of China (English)

    张红印; Fu-H sianChang; 陈少峰

    2011-01-01

    [目的]利用马铃薯残渣为原料合成乳酸预聚物,为聚乳酸的生产工艺改造提供理论依据.[方法]将由马铃薯残渣发酵所得的乳酸采用熔融缩聚法合成乳酸预聚物,并对此方法进行了优化.[结果]最佳工艺:催化剂辛酸亚锡的用量1%,熔融缩聚时间10 h,反应温度170℃,1,4-丁二醇用量1%.[结论]熔融缩聚法聚合所得的聚乳酸预聚物的最高分子量为3059 g/mol,用马铃薯残渣为原料合成乳酸预聚物简单易行,该方法提供了一种新的废物利用途径.%[Objective]The synthesis of hydroxyl terminated prepolyraer of polylactic acid using potato waste was studied to provide theoretical basis for reformation of productive technology of polylactic acid. [ Methods ] This study applied direct condensation method for polymerization of lactic acid produced from potato waste and the methods were optimized. [ Result]The results showed the following optimum conditions for polymerization :catalyst dosage:1%,reaction time: 10 h,reaction temperature; 170℃ ,1,4 - Butanediol dosage;1%. [Conclusion]The highest molecular weight of polylactic acid prepolymer obtained by melt condensation polymerization reached 3 059 g/mol. This study provides an alternative substitute for polylactic acid synthesis,which helps transfer low value potato waste to high value product.

  1. Controlled release of drug and better bioavailability using poly(lactic acid-co-glycolic acid) nanoparticles.

    Science.gov (United States)

    Pandey, Sanjeev K; Patel, Dinesh K; Maurya, Akhilendra K; Thakur, Ravi; Mishra, Durga P; Vinayak, Manjula; Haldar, Chandana; Maiti, Pralay

    2016-08-01

    Tamoxifen (Tmx) embedded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (PLGA-Tmx) is prepared to evaluate its better DNA cleavage potential, cytotoxicity using Dalton's lymphoma ascite (DLA) cells and MDA-MB231 breast cancer cells. PLGA-Tmx nanoparticles are prepared through emulsified nanoprecipitation technique with varying dimension of 17-30nm by changing the concentrations of polymer, emulsifier and drug. Nanoparticles dimension are measured through electron and atomic force microscopy. Interactions between tamoxifen and PLGA are verified through spectroscopic and calorimetric methods. PLGA-Tmx shows excellent DNA cleavage potential as compared to pure Tmx raising better bioavailability. In vitro cytotoxicity studies indicate that PLGA-Tmx reduces DLA cells viability up to ∼38% against ∼15% in pure Tmx. Hoechst stain is used to detect apoptotic DLA cells through fluorescence imaging of nuclear fragmentation and condensation exhibiting significant increase of apoptosis (70%) in PLGA-Tmx vis-à-vis pure drug (58%). Enhanced DNA cleavage potential, nuclear fragmentation and condensation in apoptotic cells confirm greater bioavailability of PLGA-Tmx as compared to pure Tmx in terms of receptor mediated endocytosis. Hence, the sustained release kinetics of PLGA-Tmx nanoparticles shows much better anticancer efficacy through enhanced DNA cleavage potential and nuclear fragmentation and, thereby, reveal a novel vehicle for the treatment of cancer. PMID:27112980

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

    International Nuclear Information System (INIS)

    Biodegradable hydrogels prepared by γ-irradiation from microbial poly (amino acid)s have been studied. pH-Sensitive hydrogels were prepared by means of γ-irradiation of poly(γ-glutamic acid) (PGA) produced by Bacillus subtilis and poly(ε-lysine) (PL) produced by Streptomyces albulus in aqueous solutions. When a dosage of γ-irradiation was 19 kGy or more and a concentration of PGA in water was 2 wt% or more, transparent hydrogels could be produced. In the case of 19 kGy, 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 was decreased to 200 increasing in the γ-irradiation dose over 100 kGy. Under acid conditions or on addition of electrolytes, PGA hydrogels shrinked. PGA hydrogel was pH-sensitive and changed the volume of the hydrogel depend on the value of pH outside hydrogel in the swelling medium. This PGA hydrogel was hydrodegradable and biodegradable. New novel purifier reagent (coagulant), made from PGA hydrogels, for contaminated turbid water was found and developed by Japanese venture company. Very small amount of this coagulant (only 1 ppm in turbid water) can work for purification of turbid water. PL aqueous solution also can change to hydrogel by γ-irradiation. The specific water content of PL hydrogel was range from 20 to 160 depend on the preparation conditions. Under acid conditions, the PL hydrogel swelled due to 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. (author)

  3. Biodegradability of terephthalic acid in terylene artificial silk printing and dyeing wastewater

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    As the characteristic pollutant, terephthalic acid(TA)was in charge of 40%-78% of the total COD of terylene artificial silk printing and dyeing wastewater(TPW-water). The studies on biodegradability of TA were conducted in a serial of activated sludge reactors with TPW-water. TA appeared to be readily biodegradable with removal efficiency over 96.5% under aerobic conditions, hardly biodegradable with removal efficiency below 10% under anoxic conditions and slowly biodegradable with a turnover between 31.4% and 56.0% under anaerobic conditions. TA also accounted for the majority of BOD in TPW-water. The process combined by anoxic, anaerobic and aerobic activated sludge reactor was suitable for TA degradation and TPW-water treatment. Further, the aerobic process was essentially much more effective than the anaerobic or anoxic one to degrade TA in TPW-water.

  4. Synthesis and characterization of poly(lactic acid)/ montmorillonite nanocomposites by in situ polycondensation catalyzed by non-metal-based compound.

    Science.gov (United States)

    Kaewprapan, Kulwadee; Phattanarudee, Siriwan

    2012-01-01

    Poly(lactic acid)/montmorillonite nanocomposites were prepared by using non-toxic catalysts, i.e., phthalic acid and succinimide, via in situ polycondensation in presence of silicate. Concentrations of catalysts and clay were varied in a range of 0-3% wt and 0-0.5% wt, respectively. The reaction condition was controlled at 180 degrees C for 24 hr under a reduced pressure. Viscosity average molecular weight of the synthesized polymers and nanocomposites were characterized and compared using an Ubbelohde viscometer. Pattern of silicate distribution in the composites was investigated by X-ray diffraction to correlate with thermal properties evaluated by differential scanning calorimetry and thermogravimetric analysis. The results showed that the addition of catalysts at 2% wt gave the highest product yield (55-60%). The presence of silicate affected on molecular weight reduction, and the diffracted patterns suggested an intercalated structure. With a small amount of added filler, a significant improvement in thermal property and crystallinity of the resultant composites was obtained compared to those of the catalyzed polymers, in which the composites with succinimide exhibited overall better thermal stability and higher crystallinity than the ones prepared with phthalic acid. PMID:22524057

  5. A novel biodegradable nicotinic acid/calcium phosphate composite coating on Mg–3Zn alloy

    International Nuclear Information System (INIS)

    A novel biodegradable composite coating is prepared to reduce the biodegradation rate of Mg–3Zn alloy. The Mg–3Zn substrate is first immersed into 0.02 mol L−1 nicotinic acid (NA) solution, named as vitamin B3, to obtain a pretreatment film, and then the electrodeposition of calcium phosphate coating with ultrasonic agitation is carried out on the NA pretreatment film to obtain a NA/calcium phosphate composite coating. Surface morphology is observed by scanning electron microscopy (SEM). Chemical composition is determined by X-ray diffraction (XRD) and EDX. Protection property of the coatings is evaluated by electrochemical tests. The biodegradable behavior is investigated by immersion tests. The results indicate that a thin but compact bottom layer can be obtained by NA pretreatment. The electrodeposition calcium phosphate coating consists of many flake particles and ultrasonic agitation can greatly improve the compactness of the coating. The composite coating is biodegradable and can reduce the biodegradation rate of Mg alloys in stimulated body fluid (SBF) for twenty times. The biodegradation process of the composite coating can be attributed to the gradual dissolution of the flake particles into chippings. - Highlights: ► NA/calcium phosphate composite coating is prepared to protect Mg–3Zn alloy implant. ► Nicotinic acid (vitamin B3) is available to obtain a protective bottom film. ► Ultrasonic agitation greatly improves the compactness of calcium phosphate coating. ► The composite coating can reduce the biodegradation rate of Mg–3Zn twenty times. ► The composite coating is biodegraded by the dissolution of flakes into chippings.

  6. A novel biodegradable nicotinic acid/calcium phosphate composite coating on Mg-3Zn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yingwei, E-mail: ywsong@imr.ac.cn; Shan, Dayong; Han, En-Hou

    2013-01-01

    A novel biodegradable composite coating is prepared to reduce the biodegradation rate of Mg-3Zn alloy. The Mg-3Zn substrate is first immersed into 0.02 mol L{sup -1} nicotinic acid (NA) solution, named as vitamin B{sub 3}, to obtain a pretreatment film, and then the electrodeposition of calcium phosphate coating with ultrasonic agitation is carried out on the NA pretreatment film to obtain a NA/calcium phosphate composite coating. Surface morphology is observed by scanning electron microscopy (SEM). Chemical composition is determined by X-ray diffraction (XRD) and EDX. Protection property of the coatings is evaluated by electrochemical tests. The biodegradable behavior is investigated by immersion tests. The results indicate that a thin but compact bottom layer can be obtained by NA pretreatment. The electrodeposition calcium phosphate coating consists of many flake particles and ultrasonic agitation can greatly improve the compactness of the coating. The composite coating is biodegradable and can reduce the biodegradation rate of Mg alloys in stimulated body fluid (SBF) for twenty times. The biodegradation process of the composite coating can be attributed to the gradual dissolution of the flake particles into chippings. - Highlights: Black-Right-Pointing-Pointer NA/calcium phosphate composite coating is prepared to protect Mg-3Zn alloy implant. Black-Right-Pointing-Pointer Nicotinic acid (vitamin B{sub 3}) is available to obtain a protective bottom film. Black-Right-Pointing-Pointer Ultrasonic agitation greatly improves the compactness of calcium phosphate coating. Black-Right-Pointing-Pointer The composite coating can reduce the biodegradation rate of Mg-3Zn twenty times. Black-Right-Pointing-Pointer The composite coating is biodegraded by the dissolution of flakes into chippings.

  7. Molecular Design of Synthetic Biodegradable Polymers as Cell Scaffold Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Shen-guo; WAN Yu-qing; CAI Qing; HE Bin; CHEN Wen-na

    2004-01-01

    Poly(lactic acid) and its copolymers are regarded as the most useful biomaterials. The good biocompatibility, biodegradability and mechanical properties of them make the synthetic biodegradable polymers have primary application to tissue engineering. The advantages and disadvantages of the synthetic biodegradable polymers as cell scaffold materials are evaluated. This article reviews the modification of polylactide-family aliphatic polymers to improve the cell affinity when the polymers are used as cell scaffolds. We have developed four main approaches: to modify polyester cell scaffolds in combination of plasma treating and collagen coating; to introduce hydrophilic segments into aliphatic polyester backbones; to introduce pendant functional groups into polyester chains; to modify polyester with dextran. The results of the cell cultures prove that the approaches mentioned above have improved the cell affinity of the polyesters and have modulated cell function such as adhesion, proliferation and migration.

  8. Processing and study of properties of films and injected pieces of nanobiocomposites of cellulose whiskers and biodegradable polymers

    OpenAIRE

    Morelli, Carolina Lipparelli

    2014-01-01

    This study aimed at evaluating the potential of application of cellulose nanocrystals as reinforcing elements of biodegradable polymeric matrices, in the films and injection molded pieces applications. Two polymeric matrices with different properties were used, namely: poly(butylene adipate-co-terephthalate), PBAT, and poly(lactic acid), PLA. For the extraction of cellulose nanocrystals (NCC), two sources were selected: microcrystalline cellulose (CMC) and balsa wood . Due to the high polarit...

  9. Impact Strength and Flexural Properties Enhancement of Methacrylate Silane Treated Oil Palm Mesocarp Fiber Reinforced Biodegradable Hybrid Composites

    OpenAIRE

    Chern Chiet Eng; Nor Azowa Ibrahim; Norhazlin Zainuddin; Hidayah Ariffin; Wan Md Zin Wan Yunus

    2014-01-01

    Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composite...

  10. Preparation and toxicity test of chitosan-polylactic acid film%壳聚糖聚乳酸膜的制备和毒性试验研究

    Institute of Scientific and Technical Information of China (English)

    陈康; 李瑛; 谢良宪

    2011-01-01

    Objective To manufacture a biomembrane for the primary repair of colonic fistula, and to evaluate its acute general toxicity and cytotoxicity. Methods After the preparation of polylactic acid film( PAF )and chitosan - polylactic acid film ( CPAF ), acute general toxicity and cytotoxicity examinations were performed with trypanblau cytoactive count and MTT reduction assay according to pharmacopeia for CPAF. Results A method for the preparation of CPAF was successfully established. There were no significant differences in physical performances between PAF and CPAF. No death and paradoxical reaction in mice were found by acute general toxicity test. Trypanblau cytoactive count and MTT reduction assay showed no significant differences between the two biofilms.Conclusion CPAF meets physic requirement of pharmacopeia with no acute general toxicity and cytotoxicity. Its biocompatibility is good according to preliminary assessment.%目的 研制结肠瘘的一期修复生物膜,并进行相关急性毒性和细胞毒性试验.方法 制备聚乳酸膜和壳聚糖聚乳酸膜,按照药典要求进行壳聚糖聚乳酸膜的小鼠急性全身毒性试验和细胞毒性试验(台盼蓝计数细胞活性和MTT法检测细胞活性).结果 建立了壳聚糖聚乳酸膜的制备方法,聚乳酸膜与壳聚糖聚乳酸膜的物理性能比较无统计学差异;小鼠急性全身毒性试验无动物死亡和异常反应;细胞毒性试验显示,两膜比较无统计学差异.结论 壳聚糖聚乳酸膜的物理指标达到药典要求,无急性全身毒性反应和细胞毒性反应,初步评价生物相容性好.

  11. Engineered biosynthesis of biodegradable polymers.

    Science.gov (United States)

    Jambunathan, Pooja; Zhang, Kechun

    2016-08-01

    Advances in science and technology have resulted in the rapid development of biobased plastics and the major drivers for this expansion are rising environmental concerns of plastic pollution and the depletion of fossil-fuels. This paper presents a broad view on the recent developments of three promising biobased plastics, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and polybutylene succinate (PBS), well known for their biodegradability. The article discusses the natural and recombinant host organisms used for fermentative production of monomers, alternative carbon feedstocks that have been used to lower production cost, different metabolic engineering strategies used to improve product titers, various fermentation technologies employed to increase productivities and finally, the different downstream processes used for recovery and purification of the monomers and polymers. PMID:27260524

  12. Synthesis and characterization of biodegradable polymer: Poly (ethene maleic acid ester-co-D,L-lactide acid)

    Institute of Scientific and Technical Information of China (English)

    Mei Na Huang; Yan Feng Luo; Jia Chen; Yong Gang Li; Chun Hua Fu; Yuan Liang Wang

    2007-01-01

    A novel biodegradable polymer-poly (ethene maleic acid ester-co-D,L-lactide acid) was synthesized by copolymerizing lactide and prepolymer, which was prepared by the condensation of maleic anhydride and glycol, using p-toluene sulphonic acid as a catalyst, attempting to improve the hydrophilicity, increase flexibility and modulate the degradation rate. FTIR, 1H NMR, MALLS and DSC were employed to characterize these polymers.

  13. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil.

    Science.gov (United States)

    Bonan, Roberta F; Bonan, Paulo R F; Batista, André U D; Sampaio, Fábio C; Albuquerque, Allan J R; Moraes, Maria C B; Mattoso, Luiz H C; Glenn, Gregory M; Medeiros, Eliton S; Oliveira, Juliano E

    2015-03-01

    In this study poly(lactic acid) (PLA) and polyvinylpyrrolidone (PVP) micro- and nanofiber 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 containing 20% (wt.%) oil were spun and characterized by scanning electron microscopy (SEM) and by studying the surface contact angle, in vitro release rate, and antimicrobial activity. All compositions evaluated were able to produce continuous and smooth fibers by SBS. The addition of PVP increased fiber diameter, and decreased the surface contact angle. GC analysis demonstrated that the main component of the Copaiba oil was β-caryophyllene, a known antimicrobial agent. In vitro release tests of Copaiba oil volatiles demonstrated a higher release rate in fibers containing PVP. Fiber mats made from blends containing higher amounts of PVP had greater antimicrobial action against Staphylococcus aureus. The results confirm the potential of the fiber mats for use in controlled drug release and could lead to promising applications in the biomedical field. PMID:25579936

  14. 3D-printed polylactic acid supports for enhanced ionization efficiency in desorption electrospray mass spectrometry analysis of liquid and gel samples.

    Science.gov (United States)

    Elviri, Lisa; Foresti, Ruben; Bianchera, Annalisa; Silvestri, Marco; Bettini, Ruggero

    2016-08-01

    The potential of 3D printing technology was here exploited to prepare tailored polylactic acid (PLA) supports for desorption electrospray ionization (DESI) experiments. PLA rough solid supports presenting wells of different shape (i.e. cylindrical, cubic and hemispherical cavities) were designed to accommodate samples of different physical state. The potentials of such supports in terms of sample loading capacity, sensitivity, signal stability were tested by analysing a peptide (i.e. insulin) and an aminoglycoside antibiotic (i.e. gentamicin sulphate) from solution and a chitosan-based gel. The results obtained were compared with those obtained by using a traditional polytetrafluoroethylene (PTFE) support and discussed. By using PLA support on the flat side, signal intensity improved almost twice with respect to PTFE support, whereas with spherical wells a five times improved signal sensitivity and good stability (RSD3D printing technology for the development of devices for a DESI source, presenting different shapes or configuration as a function of the sample types. PMID:27216689

  15. Accelerating calcium phosphate growth on NaOH-treated poly-(lactic- co-glycolic acid) by evaporation-induced surface crystallization

    Science.gov (United States)

    Duan, Ke; Tang, Allen; Wang, Rizhi

    2008-12-01

    Poly(lactic- co-glycolic acid) (PLGA) is a promising material for the regeneration of bone tissue, but its surface properties are not optimal for the application. Coating the surface of PLGA with a continuous layer of calcium phosphate is an effective approach to address the limitation. Current coating techniques for PLGA require immersion in supersaturated calcium phosphate solutions for days to weeks. In this study, we report a simple technique to accelerate the coating process to only 2 h immersion in supersaturated solutions. PLGA pellets were first treated with NaOH to increase their hydrophilicity. The NaOH-treated PLGA pellets were repeatedly dipped in a supersaturated calcium phosphate solution and dried in air. After 10 times of the dip-and-dry treatment, a layer of calcium phosphate crystallites uniformly covered the surfaces of the pellets. After the crystallite-covered pellets were immersed in the supersaturated solution for 2 h, about 5-μm thick continuous calcium phosphate coatings formed on the surfaces. The dip-and-dry technique was also applied on a variety of metals and porous structures. An evaporation-induced surface crystallization process was suggested as the mechanism for the dip-and-dry treatment.

  16. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

    Energy Technology Data Exchange (ETDEWEB)

    Bonan, Roberta F. [Departamento de Engenharia de Materiais (DEMAT), Universidade Federal da Paraíba (UFPB), Cidade Universitária, 58.051-900 João Pessoa, PB (Brazil); Centro de Ciências da Saúde (CCS), Universidade Federal da Paraíba (UFPB), Cidade Universitária, 58.051-900 João Pessoa, PB (Brazil); Bonan, Paulo R.F.; Batista, André U.D.; Sampaio, Fábio C.; Albuquerque, Allan J.R. [Centro de Ciências da Saúde (CCS), Universidade Federal da Paraíba (UFPB), Cidade Universitária, 58.051-900 João Pessoa, PB (Brazil); Moraes, Maria C.B. [Embrapa Recursos Genéticos e Biotecnologia, Parque Estação Ecológica, W/5 Norte (Final) Cenargen (Laboratório de Semioquímicos) ASA NORTE, 70770900 Brasília, DF (Brazil); Mattoso, Luiz H.C. [Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação Agropecuária (CNPDIA), Rua XV de Novembro, 1452, Centro, 13.560, 970 São Carlos, SP (Brazil); Glenn, Gregory M. [United States Department of Agriculture (USDA), Western Regional Research Center (WRRC), Bioproduct Chemistry and Engineering - BCE, Albany, CA 94710 (United States); and others

    2015-03-01

    In this study poly(lactic acid) (PLA) and polyvinylpyrrolidone (PVP) micro- and nanofiber 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 containing 20% (wt.%) oil were spun and characterized by scanning electron microscopy (SEM) and by studying the surface contact angle, in vitro release rate, and antimicrobial activity. All compositions evaluated were able to produce continuous and smooth fibers by SBS. The addition of PVP increased fiber diameter, and decreased the surface contact angle. GC analysis demonstrated that the main component of the Copaiba oil was β-caryophyllene, a known antimicrobial agent. In vitro release tests of Copaiba oil volatiles demonstrated a higher release rate in fibers containing PVP. Fiber mats made from blends containing higher amounts of PVP had greater antimicrobial action against Staphylococcus aureus. The results confirm the potential of the fiber mats for use in controlled drug release and could lead to promising applications in the biomedical field. - Highlights: • An efficient method for production of antimicrobial nanofiber mats using solution blow spinning was reported. • Nanofiber mats containing Copaiba oil were efficient against Staphylococcus aureus. • Nanofiber composition changed morphological properties and antimicrobial action.

  17. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

    International Nuclear Information System (INIS)

    In this study poly(lactic acid) (PLA) and polyvinylpyrrolidone (PVP) micro- and nanofiber 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 containing 20% (wt.%) oil were spun and characterized by scanning electron microscopy (SEM) and by studying the surface contact angle, in vitro release rate, and antimicrobial activity. All compositions evaluated were able to produce continuous and smooth fibers by SBS. The addition of PVP increased fiber diameter, and decreased the surface contact angle. GC analysis demonstrated that the main component of the Copaiba oil was β-caryophyllene, a known antimicrobial agent. In vitro release tests of Copaiba oil volatiles demonstrated a higher release rate in fibers containing PVP. Fiber mats made from blends containing higher amounts of PVP had greater antimicrobial action against Staphylococcus aureus. The results confirm the potential of the fiber mats for use in controlled drug release and could lead to promising applications in the biomedical field. - Highlights: • An efficient method for production of antimicrobial nanofiber mats using solution blow spinning was reported. • Nanofiber mats containing Copaiba oil were efficient against Staphylococcus aureus. • Nanofiber composition changed morphological properties and antimicrobial action

  18. Development of a novel controlled-release nanocomposite based on poly(lactic acid) to increase the oxidative stability of soybean oil.

    Science.gov (United States)

    Almasi, Hadi; Ghanbarzadeh, Babak; Dehghannya, Jalal; Entezami, Ali Akbar; Khosrowshahi Asl, Asghar

    2014-01-01

    A poly(lactic acid) (PLA)-based nanocomposite active packaging was developed for the controlled release of tert-butylhydroquinone (TBHQ) antioxidant. The PLA-based active films were loaded with only TBHQ (3% wt) or a mixture of modified cellulose nanofibre (MCNF) (8% wt) and TBHQ (3% wt) to obtain active and nanocomposite active films, respectively. Release studies indicated that the release rate of TBHQ in 95% ethanol simulant was significantly decreased by the addition of MCNF. Moreover, the presence of MCNF diminished the increasing effect of temperature on the release rate as when storage temperature increased from 4°C to 40°C. The diffusion coefficient (D) for PLA-TBHQ and PLA-MCNF-TBHQ films increased from 6.75 and 4.34 × 10(-8) cm(2) s(-1) to 19.85 and 8.49 × 10(-8) cm(2) s(-1), respectively. Diffusion of TBHQ to soybean oil was enough to delay the induction of the oxidation of soybean oil stored for 6 months in contact with PLA-based films. Antioxidative activity of PLA-based active films considerably increased with increasing storage time as indicated by the increase in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and the oxidative stability index (p activity and an extended shelf-life in fatty foods. PMID:25013987

  19. Controlled Release of Linalool Using Nanofibrous Membranes of Poly(lactic acid) Obtained by Electrospinning and Solution Blow Spinning: A Comparative Study.

    Science.gov (United States)

    Souza, Michelle A; Oliveira, Juliano E; Medeiros, Eliton S; Glenn, Gregory M; Mattoso, Luiz H C

    2015-08-01

    The controlled-release of natural plant oils such as linalool is of interest in therapeutics, cosmetics, and antimicrobial and larvicidal products. The present study reports the release characteristics of linalool encapsulated at three concentrations (10, 15 and 20 wt.%) in poly(lactic acid) nanofibrous membranes produced by electrospinning and solution blow spinning (SBS) as well as the effect of linalool on fiber morphology and structural properties. PLA nanofibrous membranes were characterized by Scanning Electron Microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and contact angle measurements. The average diameters of the electrospun and solution blow spun nanofibers were similar, ranging from 176 to 240 nm. Linalool behaved as a plasticizer to PLA decreasing the glass transition temperature (Tg), melting point (Tm) and crystallization temperature (TC) of PLA. Curves of the release of linalool at 35 °C were non-linear, showing a clear biphasic pattern consistent with one or more Fickian release components. The time required to release 50% of linalool (t1/2) decreased with increasing linalool concentration. The range in t1/2 values for SBS nanofibers was higher (291-1645s) than the t1/2 values for electrospun fibers (76-575s). PMID:26369129

  20. Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

    Science.gov (United States)

    Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

    2016-02-10

    The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface. PMID:26686158

  1. Enhancement of Mechanical and Dynamic Mechanical Properties of Hydrophilic Nanoclay Reinforced Polylactic Acid/Polycaprolactone/Oil Palm Mesocarp Fiber Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Chern Chiet Eng

    2014-01-01

    Full Text Available In previous studies, the effect of the addition of 1 wt% hydrophilic nanoclay on polylactic acid (PLA/polycaprolactone (PCL/oil palm mesocarp fiber (OPMF biocomposites was investigated by tensile properties, thermogravimetric analysis (TGA, and scanning electron microscopy (SEM. The current studies focus on the effect of addition of 1 wt% hydrophilic nanoclay on mechanical (flexural and impact properties and dynamic mechanical properties of composites. The composites were characterized by the Fourier transform infrared spectroscopy (FTIR and dynamic mechanical analysis (DMA. FTIR spectra show that peak shifting occurs when 1 wt% hydrophilic nanoclay was added to composites. The addition of 1 wt% hydrophilic nanoclay successfully improves the flexural properties and impact resistance of the biocomposites. The storage modulus of biocomposites was decreased when nanoclay was added which indicates that the stiffness of biocomposites was reduced. The loss modulus curve shows that the addition of nanoclay shift two tg in composites become closer to each other which indicates that the incorporation of nanoclay slightly compatibilizes the biocomposites. Tan δ indicated that hybrid composites dissipate less energy compared to biocomposites indicate that addition of clay to biocomposites improves fiber/matrix adhesion. Water sorption test shows that the addition of nanoclay enhances water resistance of composites.

  2. Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview.

    Science.gov (United States)

    Liss, S N; Bicho, P A; Saddler, J N

    1997-07-01

    Resin acids, a group of diterpenoid carboxylic acids present mainly in softwood species, are present in many pulp mill effluents and toxic to fish in recipient waters. They are considered to be readily biodegradable. However, their removal across biological treatment systems has been shown to vary. Recent studies indicate that natural resin acids and transformation products may accumulate in sediments and pose acute and chronic toxicity to fish. Several resin acid biotransformation compounds have also been shown to bioaccumulate and to be more resistant to biodegradation than the original material. Until recently, the microbiology of resin-acid degradation has received only scant attention. Although wood-inhabiting fungi have been shown to decrease the level of resin present in wood, there is no conclusive evidence that fungi can completely degrade these compounds. In contrast, a number of bacterial isolates have recently been described which are able to utilize dehydroabietic or isopimaric acids as their sole carbon source. There appears to be an unusually high degree of substrate specificity with respect of the utilization of abietane congeners and the presence of substituents. Pimaranes do not appear to be attacked to the same extent as the abietanes. This paper reviews the occurrence, chemistry, toxicity, and biodegradation of resin acids in relation to the biological treatment of pulp and paper mill effluents. PMID:9246738

  3. Synthesis and characterization of new biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Two novel biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups were synthesized via the macromolecular substitution reactions of poly(dichlorophosphazene) with the sodium salt of lactic acid ester and sodium methoxyethoxyethoxide.Their structures were confirmed by ~(31)p NMR,~1H NMR,~(13)C NMR,IR,DSC,and elemental analysis.The lower critical solution temperature(LCST) behavior in water and in vitro degradation property of the polymers was investigated....

  4. Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation.

    Science.gov (United States)

    Shibata, Akimichi; Yada, Shuhei; Terakawa, Mitsuhiro

    2016-01-01

    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. PMID:27301578

  5. Enhanced Biodegradability, Lubricity and Corrosiveness of Lubricating Oil by Oleic Acid Diethanolamide Phosphate

    Directory of Open Access Journals (Sweden)

    Fang Jianhua

    2012-09-01

    Full Text Available Impacts of oleic acid diethanolamide phosphate (abbreviated as ODAP as an additive on biodegradability, anti-wear capacity, friction-reducing ability and corrosiveness of an unreadily biodegradable HVI 350 mineral lubricating oil was studied. The biodegradabilities of neat lubricating oil and its formulations with ODAP were evaluated on a biodegradation tester. Furthermore, the anti-wear and friction-reducing abilities and the corrosiveness of neat oil and the formulated oils were determined on a four-ball tribotester and a copper strip corrosion tester, respectively. The results indicated that ODAP markedly enhanced biodegradability as well as anti-wear and friction-reducing abilities of the lubricating oil. On the other hand, excellent color ratings of copper strips for both neat oil and the ODAP-doped oil were obtained in the corrosion tests, demonstrating that the corrosiveness of neat oil and the doped oil was negligible, although the latter seemed to provide slightly better anti-corrosion ability.

  6. Radiation-induced grafting of acrylic acid onto polypropylene film and its biodegradability

    Science.gov (United States)

    Mandal, Dev K.; Bhunia, Haripada; Bajpai, Pramod K.; Chaudhari, C. V.; Dubey, K. A.; Varshney, L.

    2016-06-01

    Polypropylene based commodity polyolefins are widely used in packaging, manufacturing, electrical, pharmaceutical and other applications. The aim of the present work is to study the effect of grafting of acrylic acid on the biodegradability of acrylic acid grafted polypropylene. The effect of different conditions showed that grafting percentage increased with increase in monomer concentration, radiation dose and inhibitor concentration but decreased with increase in radiation dose rate. The maximum grafting of 159.4% could be achieved at optimum conditions. The structure of grafted polypropylene films at different degree of grafting was characterized by EDS, FTIR, TGA, DSC, SEM and XRD. EDS studies showed that the increase in acrylic acid grafting percentage increased the hydrophilicity of the grafted films. FTIR studies indicated the presence of acrylic acid on the surface of polypropylene film. TGA studies revealed that thermal stability decreased with increase in grafting percentage. DSC studies showed that melting temperature and crystallinity of the grafted polypropylene films lower than polypropylene film. SEM studies indicated that increase in acrylic acid grafting percentage increased the wrinkles in the grafted films. The maximum biodegradability could be achieved to 6.85% for 90.5% grafting. This suggested that microorganisms present in the compost could biodegrade acrylic acid grafted polypropylene.

  7. Preparation of biodegradable PLA/PLGA membranes with PGA mesh and their application for periodontal guided tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Jin; Kang, Inn-Kyu [Department of Polymer Science, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu 702-701 (Korea, Republic of); Yoon, Suk Joon [Department of Biology, Sookmyung Women' s University, Hyochangwongil 52, Yongsan-gu, Seoul 140-742 (Korea, Republic of); Yeo, Guw-Dong; Pai, Chaul-Min, E-mail: ikkang@knu.ac.k [Samyang Central R and D Center, 63-2 Hwaam-dong, Yusung-gu, Daejeon 305-717 (Korea, Republic of)

    2009-10-15

    A biodegradable polylactic acid (PLA)/poly(glycolide-co-lactide) copolymer (PLGA) membrane with polyglycolic acid (PGA) mesh was prepared to aid the effective regeneration of defective periodontal tissues. The microporous membrane used in this study consists of biodegradable polymers, and seems to have a structure to provide appropriate properties for periodontal tissue regeneration. Based on the albumin permeation test, it is known that the biodegradable membrane exhibits the suitable permeability of nutrients. The membrane maintained its physical integrity for 6-8 weeks, which could be sufficient to retain space in the periodontal pocket. Cell attachment and cytotoxicity tests were performed with respect to the evaluation of biocompatibility of the membrane. As a result, the membrane did not show any cytotoxicity. The safety and therapeutic efficacies of the biodegradable membranes were confirmed in animal tests.

  8. Preparation of biodegradable PLA/PLGA membranes with PGA mesh and their application for periodontal guided tissue regeneration

    International Nuclear Information System (INIS)

    A biodegradable polylactic acid (PLA)/poly(glycolide-co-lactide) copolymer (PLGA) membrane with polyglycolic acid (PGA) mesh was prepared to aid the effective regeneration of defective periodontal tissues. The microporous membrane used in this study consists of biodegradable polymers, and seems to have a structure to provide appropriate properties for periodontal tissue regeneration. Based on the albumin permeation test, it is known that the biodegradable membrane exhibits the suitable permeability of nutrients. The membrane maintained its physical integrity for 6-8 weeks, which could be sufficient to retain space in the periodontal pocket. Cell attachment and cytotoxicity tests were performed with respect to the evaluation of biocompatibility of the membrane. As a result, the membrane did not show any cytotoxicity. The safety and therapeutic efficacies of the biodegradable membranes were confirmed in animal tests.

  9. Study on double-end hydroxyl poly(lactic acid) with controlled polymerization degree by condensation%聚合度可控的双端羟聚乳酸的缩聚合成研究

    Institute of Scientific and Technical Information of China (English)

    吴传保; 孙平; 刘祥丽; 曾湘晖; 刘利江

    2013-01-01

    In order to explore the method of regulating poly(lactic acid) polymerization degree and end group type in the process of lactic acid direct polycondensation,and open up new areas of synthesizing poly(lactic acid)-based functional polymers by direct polycondensation,glycol was selected as examples to study lactic acid direct polycondensation under the conditions of adding diols.1H NMR was used to characterize product structure and viscosity and mass determinations were used to track reaction process.Experimental results show that the addition of glycol is useful to regulate the polymerization degree of poly(lactic acid) due to changing relative amount of hydroxyl and carboxyl functional groups.The method of calculating theoretical polymerization degree of poly(lactic acid) was obtained through experimental study.This study provides preliminary research basis for improving direct polycondensation method to obtain poly (lactic acid) with particular polymerization degree and increase control accuracy of polymerization degree.%为了探索在乳酸直接缩聚过程中调控聚合度及端基类型的方法和开辟通过直接缩聚合成聚乳酸基功能高分子的新领域,以乙二醇为例,对二元醇存在条件下的乳酸直接缩聚进行了研究.通过1H NMR对产物的结构进行了表征,通过测定质量及黏度对反应过程进行了跟踪.实验结果表明,加入乙二醇后,由于羟基与羧基官能团相对量的改变,对聚乳酸聚合度具有调控作用.通过实验研究得出了添加乙二醇条件下的理论聚合度的计算方法.本研究为通过直接缩聚合成具有特定聚合度的遥爪型聚乳酸大分子单体,进而合成聚乳酸基功能高分子奠定了基础.

  10. Mandibular bone repair by implantation of rhBMP-2 in a slow release carrier of polylactic acid--an experimental study in rats.

    Science.gov (United States)

    Schliephake, Henning; Weich, Herbert A; Dullin, Christian; Gruber, Rudolf; Frahse, Sarah

    2008-01-01

    The aim of the present study was to test the hypothesis that human recombinant bone morphogenic protein 2 (rhBMP-2) implanted in a slow release carrier of polylactic acid (PLA) can repair a non-healing defect in the rat mandible and maintain the thickness of an augmented volume. p-DL-lactic acid discs were produced and loaded with 48 and 96 microg rhBMP-2 and inserted into non-healing defects of the mandible of 45 Wistar rats. Fifteen rats received implants with 96 microg rhBMP-2 (Group 2), 48 microg rhBMP-2 (Group 1) and blank implants without BMP (Group 0) each on one side of the mandible. Unfilled defects of the same size on the contralateral sides of the mandibles served as empty controls. After 6, 13 and 26 weeks, implants of each group were retrieved from five animals each and submitted to flat panel detector computed tomography. Bone formation and thickness of augmentation was assessed by computer-assisted histomorphometry. In Group 2 significantly more bone was produced than in Group 1. Implants of Group 1 induced significantly more bone than the blank controls only after 6 weeks, whereas the difference was not significant after 13 and 26 weeks. Differences between Group 2 and Group 1 were clearly significant after 26 weeks. The thickness of bone tissue was maintained in Group 2 whereas it decreased in Group 1 and was negligible in Group 0. It is concluded that the PLA implants with 96 microg rhBMP-2 were able to bridge a non-healing defect in the rat mandible and maintained the thickness of an augmented volume. However, continuous supply of osteogenic signals appears to be required to compensate for adverse effects during polymer degradation. PMID:17936352

  11. Preparation and characterizations of cellulose-polylactic acid blending material%纤维素-聚乳酸共混改性膜材料的制备及其性能的研究

    Institute of Scientific and Technical Information of China (English)

    肖舒; 戴林; 申越; 何静

    2011-01-01

    将微晶纤维素溶于离子液体中,加入不同质量的聚乳酸,配制成共混溶液并成膜。通过红外光谱对其结构进行测定,证明共混物制备成功。X-衍射、SEM及DSC测试结果表明,共混物之间具有较好的相容性,当微晶纤维素与聚乳酸的质量比为60:40时共混效果较好,较易成膜,且二者的结晶过程得到互相促进,结晶完美度及晶体尺寸提高。同时,DSC测试结果表明,不同质量比的纤维素-聚乳酸共混物具有不同的结晶度,且纤维素与聚乳酸的质量比为60:40时亦具有较好的化学及生物降解性。%The cellulose-polylactie acid blending membrane was prepared via mixed solvent method.Firstly, microcrystalline cellulose was dissolved in ionic liquid,and then a different quality of polylactic acid was added. Infrared spectroscopy(FTIR) determined that blending membrane was prepared successfully.According to the results of X-ray diffraction,SEM and DSC,the microcrystalline cellulose and polylactic acid showed good compatibility with each other.When the mass ratio of microcrystalline cellulose to polylactic acid was 60:40,the membrane was easily obtained.At the same time,the crystallization process was promoted,and crystallization degree and crystal size were also increased.The results of DSC also showed that different mass ratio of cellulosepolylactic acid membrane had different degree of crystallinity.When the mass ratio of microcrystalline cellulose to polylactic acid was 60:40,the membrane also had good chemical and biological degradation.

  12. Fabrication and characterization of a foamed polylactic acid (PLA)/ thermoplastic polyurethane (TPU) shape memory polymer (SMP) blend for biomedical and clinical applications

    Science.gov (United States)

    Song, Janice J.; Srivastava, Ijya; Kowalski, Jennifer; Naguib, Hani E.

    2014-03-01

    Shape memory polymers (SMP) are a class of stimuli-responsive materials that are able to respond to external stimulus such as heat by altering their shape. Bio-compatible SMPs have a number of advantages over static materials and are being studied extensively for biomedical and clinical applications (such as tissue stents and scaffolds). A previous study has demonstrated that the bio-compatible polymer blend of polylactic acid (PLA)/ thermoplastic polyurethane (TPU) (50/50 and 70/30) exhibit good shape memory properties. In this study, the mechanical and thermo-mechanical (shape memory) properties of TPU/PLA SMP blends were characterized; the compositions studied were 80/20, 65/35, and 50/50 TPU/PLA. In addition, porous TPU/PLA SMP blends were fabricated with a gas-foaming technique; and the morphology of the porous structure of these SMPs foams were characterized with scanning electron microscopy (SEM). The TPU/PLA bio-compatible SMP blend was fabricated with melt-blending and compression molding. The glass transition temperature (Tg) of the SMP blends was determined with a differential scanning calorimeter (DSC). The mechanical properties studied were the stress-strain behavior, tensile strength, and elastic modulus; and the thermomechanical (or shape memory) properties studied were the shape fixity rate (Rf), shape recovery rate (Rr), response time, and the effect of recovery temperature on Rr. The porous 80/20 PLA/TPU SMP blend was found to have the highest tensile strength, toughness and percentage extension, as well as the lowest density and uniform pore structure in the micron and submicron scale. The porous 80/20 TPU/PLA SMP blend may be further developed for specific biomedical and clinical applications where a combination of tensile strength, toughness, and low density are required.

  13. 葫芦素毫微粒冻干针剂的研究%A Study on Lyophilization Injection of Cucurbitacin Polylactic Acid Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    李超英; 侯世祥; 阳长明; 孙毅毅; 张继芬

    2001-01-01

    目的:制备稳定的、易再分散的葫芦素聚乳酸毫微粒(Cu-PLA-NP)冻干针剂。方法:选用适宜填充剂制备Cu-PLA-NP冻干针剂,并评价其相关理化性质。结果:冻干前后毫微粒形态、粒径、pH、包封率及载药量无明显变化,再分散性良好,制剂稳定,含水量合格。其临界相对湿度为69.52%。结论:在适宜的处方及工艺条件下制备的Cu-PLA-NP冻干针剂是可行的。%Objective:To prepare stable and redispersable Lyophilization injection of cucurbitacin polylactic acid nanoparticles(Cu-PLA-NP).Method:An optimal supporting agent was chosen to prepare the Cu-PLA-NP lyophilization injection.The physical and chemical properties of the injection were evaluated.Result:The shape,diameters,association ratio,drug loading and pH of Cu-PLA-NP colloidal solution and lyophilization injection were not changed.The content of water consisted with the requirement of lyophilization injection.The critical relative humidity was 69.52%.The stability was good.Conclusion:It is practicable to prepare Cu-PLA-NP lyophilization injection with proper formulas and preparation processes.

  14. Polyethylene glycol–polylactic acid nanoparticles modified with cysteine–arginine–glutamic acid–lysine–alanine fibrin-homing peptide for glioblastoma therapy by enhanced retention effect

    Directory of Open Access Journals (Sweden)

    Wu J

    2014-11-01

    Full Text Available Junzhu Wu,1,2,* Jingjing Zhao,1,3,* Bo Zhang,1 Yong Qian,1 Huile Gao,1 Yuan Yu,1 Yan Wei,1 Zhi Yang,1 Xinguo Jiang,1 Zhiqing Pang1 1Key Laboratory of Smart Drug Delivery, Ministry of Education, Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai, 2School of Pharmacy, Dali University, Xiaguan, 3School of Pharmacy, China Pharmaceutical University, Nanjing, People’s Republic of China *These authors contributed equally to this work Abstract: For a nanoparticulate drug-delivery system, crucial challenges in brain-glioblastoma therapy are its poor penetration and retention in the glioblastoma parenchyma. As a prevailing component in the extracellular matrix of many solid tumors, fibrin plays a critical role in the maintenance of glioblastoma morphology and glioblastoma cell differentiation and proliferation. We developed a new drug-delivery system by conjugating polyethylene glycol–polylactic acid nanoparticles (NPs with cysteine–arginine–glutamic acid–lysine–alanine (CREKA; TNPs, a peptide with special affinity for fibrin, to mediate glioblastoma-homing and prolong NP retention at the tumor site. In vitro binding tests indicated that CREKA significantly enhanced specific binding of NPs with fibrin. In vivo fluorescence imaging of glioblastoma-bearing nude mice, ex vivo brain imaging, and glioblastoma distribution demonstrated that TNPs had higher accumulation and longer retention in the glioblastoma site over unmodified NPs. Furthermore, pharmacodynamic results showed that paclitaxel-loaded TNPs significantly prolonged the median survival time of intracranial U87 glioblastoma-bearing nude mice compared with controls, Taxol, and NPs. These findings suggested that TNPs were able to target the glioblastoma and enhance retention, which is a valuable strategy for tumor therapy. Keywords: CREKA peptide, nanoparticles, retention effect, paclitaxel, glioblastoma

  15. Novel electrospun nanofibrous matrices prepared from poly(lactic acid)/poly(butylene adipate) blends for controlled release formulations of an anti-rheumatoid agent.

    Science.gov (United States)

    Siafaka, Panoraia I; Barmbalexis, Panagiotis; Bikiaris, Dimitrios N

    2016-06-10

    In the present work, a series of novel formulations consisting of poly(lactic acid)/poly(butylene adipate) (PLA/PBAd) electrospun blends was examined as controlled release matrices for Leflunomide's active metabolite, Teriflunomide (TFL). The mixtures were prepared using different ratios of PLA and PBAd in order to produce nanofibrous matrices with different characteristics. Miscibility studies of the blended polymeric fibers were performed through differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). Hydrolytic degradation in the prepared fibers was evaluated at 37°C using a phosphate buffered saline solution. Different concentrations of (TFL) (5, 10, 15wt.%) were incorporated into nanofibers for examining the drug release behavior in simulated body fluids (SBF), at 37°C. The drug-loaded nanofibrous formulations were further characterized by Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy, DSC and XRD. Gel permeation chromatography (GPC) analysis was used to evaluate the mechanism of TFL release. Artificial neural networks (ANN) and multi-linear-regression (MLR) models were used to evaluate the effect of % content of PBAd (X1) and TFL (X2) on an initial burst effect and a dissolution behavior. It was found that PLA/PBAd nanofibers have different diameters depending on the ratio of used polyesters and added drug. TFL was incorporated in an amorphous form inside the polymeric nanofibers. In vitro release studies reveal that a drug release behavior is correlated with the size of the nanofibers, drug loading and matrix degradation after a specific time. ANN dissolution modeling showed increased correlation efficacy compared to MLR. PMID:27039136

  16. Compatibilization of immiscible poly(lactic acid)/poly(ε-caprolactone) blend through electron-beam irradiation with the addition of a compatibilizing agent

    International Nuclear Information System (INIS)

    The aim of this study was to compatibilize immiscible poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blend by using electron-beam radiation method with the addition of a compatibilizing agent. Glycidyl methacrylate (GMA) was chosen as the compatibilizing agent, in the expectation that the GMA plays a role as a monomeric compatibilizer and a reactive agent at the interface between the PLA and the PCL phases. Compatibilization process has been investigated through the melt mixing of the PLA/PCL and the GMA by using a twin-screw extruder and the exposure of the PLA/PCL/GMA mixture to electron-beam radiation at room temperature. The melt mixing process was performed to locate the GMA at the interface, thereby expecting a finer morphology due to the GMA as the monomeric plasticizer. The exposure process was carried out to induce definite interfacial adhesion at the interface through electron-beam initiated cross-copolymerization by the medium of the GMA as the reactive agent. To investigate the results of this compatibilization strategy, the morphological, mechanical, and rheological properties of the blend were analyzed. The morphological study clearly showed the reduced particle size of dispersed PCL domains and significantly improved interfacial adhesion by the electron-beam irradiation with the addition of the GMA. The stress–strain curves of the blends irradiated at less than 20 kGy showed the typical characteristics of ductile materials. The tensile properties of the blend were strongly affected by the dose of irradiation. - Highlights: ► PLA/PCL blend was compatibilized by the electron-beam irradiation with the addition of GMA. ► GMA played the role of a monomeric compatibilizer and a reactive agent at the interface. ► Definite interfacial adhesion was produced through radiation initiated cross-copolymerization. ► The stress–strain curves of blends irradiated at less than 20 kGy showed a ductile behavior.

  17. Bony defect repair in rabbit using hybrid rapid prototyping polylactic co glycolic acid/β tricalciumphosphate collagen I/apatite scaffold and bone marrow mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    Long Pang

    2013-01-01

    Full Text Available Background: In bone tissue engineering, extracellular matrix exerts critical influence on cellular interaction with porous biomaterial and the apatite playing an important role in the bonding process of biomaterial to bone tissue. The aim of this study was to observe the therapeutic effects of hybrid rapid prototyping (RP scaffolds comprising polylactic-co-glycolic acid (PLGA, β-tricalciumphosphate (β-TCP, collagen I and apatite (PLGA/β-TCP-collagen I/apatite on segmental bone defects in conjunction with combination with bone marrow mesenchymal stem cells (BMSCs. Materials and Methods: BMSCs were seeded into the hybrid RP scaffolds to repair 15 mm defect in the radius of rabbits. Radiograph, microcomputed tomography and histology were used to evaluate new bone formation. Results: Radiographic analysis done from 12 to 36 weeks postoperative period demonstrated that new bone formed at the radial defect site and continues to increase until the medullary cavity is recanalized and remodelling is complete. The bone defect remained unconnected in the original RP scaffolds (PLGA/β-TCP during the whole study. Histological observations conformed to the radiographic images. In hybrid RP scaffold group, woven bone united the radial defect at 12 weeks and consecutively remodeled into lamellar bone 24 weeks postoperation and finally matured into cortical bone with normal marrow cavity after another 12 weeks. No bone formation but connective tissue has been detected in RP scaffold at the same time. Conclusion: Collagen I/apatite sponge composite coating could improve new bone formation in vivo. The hybrid RP scaffold of PLGA/β-TCP skeleton with collagen I/apatite sponge composite coating is a promising candidate for bone tissue engineering.

  18. Biodegradation of 5-Nitroanthranilic Acid by Bradyrhizobium sp. Strain JS329▿

    OpenAIRE

    Qu, Yi; Spain, Jim C.

    2010-01-01

    Biodegradation of synthetic compounds has been studied extensively, but the metabolic diversity required for catabolism of many natural compounds has not been addressed. 5-Nitroanthranilic acid (5NAA), produced in soil by Streptomyces scabies, is also the starting material for synthetic dyes and other nitroaromatic compounds. Bradyrhizobium JS329 was isolated from soil by selective enrichment with 5NAA. When grown on 5NAA, the isolate released stoichiometric amounts of nitrite and half of the...

  19. Nanocomposites of Polyacrylic Acid Nanogels and Biodegradable Polyhydroxybutyrate for Bone Regeneration and Drug Delivery

    Directory of Open Access Journals (Sweden)

    Mikael Larsson

    2014-01-01

    Full Text Available Biodegradable cell scaffolds and local drug delivery to stimulate cell response are currently receiving much scientific attention. Here we present a nanocomposite that combines biodegradation with controlled release of lithium, which is known to enhance bone growth. Nanogels of lithium neutralized polyacrylic acid were synthesized by microemulsion-templated polymerization and were incorporated into a biodegradable polyhydroxybutyrate (PHB matrix. Nanogel size was characterized using dynamic light scattering, and the nanocomposites were characterized with regard to structure using scanning electron microscopy, mechanical properties using tensile testing, permeability using tritiated water, and lithium release in PBS using a lithium specific electrode. The nanogels were well dispersed in the composites and the mechanical properties were good, with a decrease in elastic modulus being compensated by increased tolerance to strain in the wet state. Approximately half of the lithium was released over about three hours, with the remaining fraction being trapped in the PHB for subsequent slow release during biodegradation. The prepared nanocomposites seem promising for use as dual functional scaffolds for bone regeneration. Here lithium ions were chosen as model drug, but the nanogels could potentially act as carriers for larger and more complex drugs, possibly while still carrying lithium.

  20. Biodegradation studies of selected priority acidic pesticides and diclofenac in different bioreactors

    International Nuclear Information System (INIS)

    The biodegradation of selected priority acidic pesticides MCPP, MCPA, 2,4-D, 2,4-DP and bentazone and the acidic pharmaceutical diclofenac was investigated using a membrane bioreactor (MBR) and a fixed-bed bioreactor (FBBR). A pilot plant MBR was fed with raw water spiked with the selected compounds. The experiment was repeated every week during four weeks to enhance the adaptation of microorganisms. In order to further study the biodegradability of these compounds, degradation studies in a FBBR were carried out. All the samples were analysed by solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS). The results indicate that in the MBR compounds except for bentazone were eliminated within the first day of the experiment at rates ranging from 44% to 85%. Comparing these results with the degradation rates in the FBBR showed that in the latter only MCPP, MCPA 2,4-D and 2,4-DP were degraded after a much longer adaptation phase of microorganisms. - Biodegradation rate of selected acidic pesticides and pharmaceuticals depends on adaptation

  1. Oleanolic Acid Delivery using Biodegradable Nanoparticles for Cancer Therapy

    OpenAIRE

    Man, KWD; Kwok, PCL; Lam, JKW

    2014-01-01

    Oleanolic acid (OA) is a naturally occurring pentacyclic triterpenoid widely found in Chinese herbs. It has been extensively studied owing to the beneficial effects such as hepatoprotection, anti-inflammatory and it is recently found to have anti-tumor ability. However, resembling the other hydrophobic drugs, it has poor water solubility and therefore very limited intestinal absorption when administrated orally. Investigations concerning the delivery of OA have been ...

  2. Microbial activity in an acid resin deposit: Biodegradation potential and ecotoxicology in an extremely acidic hydrocarbon contamination

    International Nuclear Information System (INIS)

    Acid resins are residues produced in a recycling process for used oils that was in use in the forties and fifties of the last century. The resin-like material is highly contaminated with mineral oil hydrocarbons, extremely acidic and co-contaminated with substituted and aromatic hydrocarbons, and heavy metals. To determine the potential for microbial biodegradation the acid resin deposit and its surroundings were screened for microbial activity by soil respiration measurements. No microbial activity was found in the core deposit. However, biodegradation of hydrocarbons was possible in zones with a lower degree of contamination surrounding the deposit. An extreme acidophilic microbial community was detected close to the core deposit. With a simple ecotoxicological approach it could be shown that the pure acid resin that formed the major part of the core deposit, was toxic to the indigenous microflora due to its extremely low pH of 0-1. - Acidity is the major toxic factor of the extremely hydrophobic and acidic mixed contamination found in an acid resin deposit

  3. Influence of clay-nanofiller geometry on the structure and properties of poly(lactic acid)/thermoplastic polyurethane nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Kelnar, Ivan; Kratochvíl, Jaroslav; Fortelný, Ivan; Kaprálková, Ludmila; Zhigunov, Alexander; Nevoralová, Martina; Kotrisová, M.; Khunová, V.

    2016-01-01

    Roč. 6, č. 36 (2016), s. 30755-30762. ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:61389013 Keywords : poly (ɛ-caprolactone) * poly (lactic acid) * microfibrillar composites Subject RIV: JI - Composite Materials Impact factor: 3.840, year: 2014

  4. Impact of acid and oxidative modifications, single or dual, of sorghum starch on biodegradable films.

    Science.gov (United States)

    Biduski, Bárbara; Silva, Francine Tavares da; Silva, Wyller Max da; Halal, Shanise Lisie de Mello El; Pinto, Vania Zanella; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2017-01-01

    The objective of this study was to evaluate the effects of acid and oxidation modifications on sorghum starch, as well as the effect of dual modification of starch on the physical, morphological, mechanical, and barrier properties of biodegradable films. The acid modification was performed with 3% lactic acid and the oxidation was performed with 1.5% active chlorine. For dual modification, the acid modification was performed first, followed by oxidation under the same conditions as above. Both films of the oxidized starches, single and dual, had increased stiffness, providing a higher tensile strength and lower elongation when compared to films based on native and single acid modified starches. However, the dual modification increased the water vapor permeability of the films without changing their solubility. The increase in sorghum starch concentration in the filmogenic solution increased the thickness, water vapor permeability, and elongation of the films. PMID:27507447

  5. Wettability Effect of PECVD-SiOx Films on Poly(lactic acid) Induced by Oxygen Plasma on Protein Adsorption and Cell Attachment

    International Nuclear Information System (INIS)

    Surface wettability is an important property of biomaterials. Silicon oxide films have a wide range of applications due to a range of the properties such as the mechanical strength and surface wettability. This paper reports effect of the surface wettability of silicon oxide (SiOx) films on protein adsorption and cell attachment and proliferation. SiOx films were deposited onto poly(lactic acid) (PLA) substrate using plasma enhanced chemical vapor deposition (PECVD). Octamethylcyclotetrasiloxane (OMCTS:Si4O4C8H24) was used as a precursor with O2 as a carrier gas. After deposition, the films were treated with O2-plasma to adapt wettability. It was found that O2-plasma enhanced the wettability of the films without changing the film thickness, while made the surface morphology slightly smoother. The polar component increased after O2-plasma treatment as observed in the contact angle measurements. The surface energy of the films was calculated by means of the Owens-Wendt method to resolve the contributions of polar and dispersive components. The chemical structure was characterized using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The films were dense with a high Si-network structure. The reduced carbon content (-CHn, Si-CH3) and increased hydrogen content (-OH) of the O2-plasma treated SiOx films led to the polar components enhancing the SiOx wettability. Adsorption of bovine serum albumin (BSA) on the films was investigated by using x-ray photoelectron spectroscopy (XPS). More BSA was adsorbed onto the O2-plasma treated SiOx films. Attachment and proliferation of MC3T3-E1 mouse pre-osteoblasts and L929 mouse fibroblasts cells on the SiOx films were evaluated via MTT assay. The cells were attached more to the untreated SiOx films but proliferated more on the surface of the O2-plasma treated SiOx films depending on the cell types.

  6. Structural basis for unique hierarchical cylindrites induced by ultrahigh shear gradient in single natural fiber reinforced poly(lactic acid) green composites.

    Science.gov (United States)

    Xu, Huan; Xie, Lan; Jiang, Xin; Hakkarainen, Minna; Chen, Jing-Bin; Zhong, Gan-Ji; Li, Zhong-Ming

    2014-05-12

    A local shear flow field was feasibly generated by pulling the ramie fiber in single fiber reinforced poly(lactic acid) (PLA) composites. This was featured by an ultrahigh shear gradient with a maximum shear rate up to 1500 s(-1), a level comparable to that frequently occurring during the practical polymer processing. To distinguish shear-induced self-nucleation and ramie fiber-induced heterogeneous nucleation, the shear history was classified by pulling the fiber for 5 s (pulled sample) and pulling out the fiber during 10 s (pulled-out sample), while the static fiber-induced crystallization was carried out as the counterpart. As a result of the ultrahigh shear gradient, the combination of primary shear-induced nucleation in the central region and secondary nucleation in the outer layer assembled the unique hierarchical superstructures. By comparing the architectural configurations of interphases formed in the static, pulled, and pulled-out samples, it was shown that the hierarchical cylindrites underwent the process of self-nucleation driven by the applied shear flow, very different from the formation of fiber-induced transcrystallinity (TC) triggered by the heterogeneous nucleating sites at the static fiber surface. The twisting of transcrystallized lamellae may take place due to the spatial hindrance induced by the incredibly dense nuclei under the intense shearing flow, as observed in the synchrotron X-ray diffraction patterns. The influence of chain characteristics on the crystalline morphology was further explored by adding a small amount of poly(ethylene glycol) (PEG) to enhance the molecular mobility of PLA. It was of interest to find that the existence of PEG not only facilitated the growth rates of TC and cylindrites but also improved the preferential orientation of PLA chains and thus expanded the ordered regions. We unearthed lamellar units that were composed of rich fibrillar extended chain crystals (diameter of 50-80 nm). These results are of

  7. Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid

    Directory of Open Access Journals (Sweden)

    Ander Orue

    2016-05-01

    Full Text Available The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid (PLA composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data.

  8. Effect of compatibilization on the properties of in situ microfibrillar composites based on polylactic acid and polypropylene

    Science.gov (United States)

    Oliviero, Maria; Buonocore, Giovanna G.; Verdolotti, Letizia; Lavorgna, Marino

    2015-12-01

    The aim of this work was to explore the feasibility of using polypropylene (PP) as an reinforcing material for polylactide acid (PLA) based on the concept of in situ microfibrillar composites (iMFCs). Microfibers of PP were successfully generated by melt mixing, slit die extrusion and cold stretching. However, due to their immiscibility feature, the interfacial interaction between PP microfibers and PLA matrix is poor. In order to reduce the interfacial tension of the blend, PP-grafted with maleic anhydride was used as an interfacial compatibilizer. The effect of filler content on morphological appearance, mechanical and water vapor barrier properties were investigated. Results show the effect of the compatibilizer to stabilize the morphology developed during compounding and to enhance adhesion between the phases thus improving the properties of the obtained iMFCs.

  9. Biodegradation of starch–graft–polystyrene and starch–graft–poly(methacrylic acid) copolymers in model river water

    OpenAIRE

    Nikolić Vladimir; Veličković Sava; Antonović Dušan; Popović Aleksandar

    2013-01-01

    In this paper the biodegradation study of grafted copolymers of polystyrene (PS) and corn starch and poly(methacrylic acid) and corn starch in model river water is described. These copolymers were obtained in the presence of different amine activators. The synthesized copolymers and products of degradation were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Biodegradation was monitored by mass decrease and number of microorganisms...

  10. Atrazine biodegradation modulated by clays and clay/humic acid complexes

    International Nuclear Information System (INIS)

    The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

  11. Optimization of process parameters for enhanced biodegradation of acid red 119 by Bacillus thuringiensis SRDD

    Directory of Open Access Journals (Sweden)

    Riddhi H. Dave

    2012-02-01

    Full Text Available Developed Bacillus thuringiensis SRDD showed degradation of C.I. Acid red 119 and growth under the extremecondition of temperature 70°C, pH 3-8, heavy metals concentration of 0.8 mM, NaCl up to 900 mM and 1000 ppm dye. Cottonseed, caster cake and corn cake powders were found to be better and cheaper nutrient supplements for the Bacillus thuringiensisSRDD for biodegradation as compared to molasses. After development of the culture and the process, more than99% degradation was achieved in less than 2 hrs of contact time even on 18th cycles of addition of 100 ppm AR-119 dye. Thedeveloped process showed AR-119 biodegradation rate as high as 220 mg L-1 h-1, which is found to be 130 times more ascompared to the reported data. U.V., FTIR, TLC and HPLC analysis data confirmed biodegradation ability of the Bacillusthuringiensis for AR-119.

  12. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  14. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amides

    Directory of Open Access Journals (Sweden)

    Angélica Díaz

    2014-04-01

    Full Text Available Poly(alkylene dicarboxylates constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amides derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  15. Biodegradable starch-based films containing saturated fatty acids: thermal, infrared and raman spectroscopic characterization

    Directory of Open Access Journals (Sweden)

    Marcelo M. Nobrega

    2012-01-01

    Full Text Available Biodegradable films of thermoplastic starch and poly (butylene adipate co-terephthalate (PBAT containing fatty acids were characterized thermally and with infrared and Raman spectroscopies. The symmetrical character of the benzene ring in PBAT provided a means to illustrate the difference between these spectroscopic techniques, because a band appeared in the Raman spectrum but not in the infrared. The thermal analysis showed three degradation stages related to fatty acids, starch and PBAT. The incorporation of saturated fatty acids with different molecular mass (caproic, lauric and stearic did not change the nature of the chemical bonds among the components in the blends of starch, PBAT and glycerol, according to the thermal analysis, infrared and Raman spectroscopies.

  16. Degradation of thin poly(lactic acid) films: Characterization by capacitance–voltage, atomic force microscopy, scanning electron microscopy and contact-angle measurements

    International Nuclear Information System (INIS)

    For the development of new biopolymers and implantable biomedical devices with predicted biodegradability, simple, non-destructive, fast and inexpensive techniques capable for real-time in situ testing of the degradation kinetics of polymers are highly appreciated. In this work, a capacitive field-effect electrolyte–insulator–semiconductor (EIS) sensor has been applied for real-time in situ monitoring of degradation of thin poly(D,L-lactic acid) (PDLLA) films over a long-time period of one month. Generally, the polymer-modified EIS (PMEIS) sensor is capable of detecting any changes in the bulk, surface and interface properties of the polymer (e.g., thickness, coverage, dielectric constant, surface potential) induced by degradation processes. The time-dependent capacitance–voltage (C–V) characteristics of PMEIS structures were used as an indicator of the polymer degradation. To accelerate the PDLLA degradation, experiments were performed in alkaline buffer solution of pH 10.6. The results of these degradation measurements with the EIS sensor were verified by the detection of lactic acid (product of the PDLLA degradation) in the degradation medium. In addition, the micro-structural and morphological changes of the polymer surface induced by the polymer degradation have been systematically studied by means of scanning-electron microscopy, atomic-force microscopy, optical microscopy, and contact-angle measurements

  17. Synthesis and Characterization of a Novel Functional Biodegradable Copolymer-Poly(lactic acid-4-hydroxyproline-polyethylene glycol)

    Institute of Scientific and Technical Information of China (English)

    Jiu Fang DUAN; Yu Bin ZHENG

    2006-01-01

    A series of poly(lactic acid-4-hydroxyproline-polyethylene glycol) (PLA-Hpr-PEG) copolymers were synthesized by direct melt copolymerization of D,L-lactic acid and 4-hydroxyproline with different feed amount of polyethylene glycol (PEG) 0.1%, 0.5%, 1% and 5%, respectively. The properties of these copolymers were characterized by using IR spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy, gel permeation chromatography (GPC), X-ray diffraction and differential scaning calorimetry (DSC). PLA-Hpr-PEG are amorphous copolymers. Copolymers showed increasing water uptake capacity with increasing PEG percentage in the feed, which result in an increasing degradable rate in phosphate buffer solution (pH 7.4) at 37℃.

  18. Investigation of in-situ poly(lactic acid)/soy protein concentrate composites: Composite preparation, properties and foam application development

    Science.gov (United States)

    Liu, Bo

    2011-12-01

    In this study, soy protein (SP), the residue of oil crushing, was used for preparation of value-added thermoplastics. Novel poly(lactic acid) (PLA)/soy protein concentrate (SPC) blends were investigated and foaming of the resulting blends was developed. PLA/SPC blends were prepared by twin-screw extrusion and test specimens by injection molding. Unlike the practice elsewhere SP was used as a filler in mixing with other polymers, SPC was processed as a plastic component in blending process in this work. Processing SPC as plastic component, water played an important role in terms of the deformability and the morphology of SP thus the properties of the blends. Plasticization of SP, compatibilization of the blends and structure-property relationship of the PLA/SPC blends were studied. In the literature water and glycerol were often used together in preparing SP plastics or plastic blends, but this study found that this traditional combination did not provide the best results in terms of morphology and mechanical properties. Water is only recommended in plasticizing SP in the blends. This study showed water as a plasticizer was a domain factor on control of morphology and properties of PLA/SPC blends. The due to the evaporation of water after extrusion, SP domain lost its deformability thus resulted in in-situ composites. Interconnected SPC phase structure was achieved by control water content in the pre-formulated SPC and SPC content in the blends. A novel dual compatibilization method was developed to improve the properties of PLA/SPC blends. Poly(2-ethyl-2-oxazoline) was used to improve the dispersion of SPC in the blending stage, and polymeric methylene diphenyl diisocyanate was used to improve the interfacial adhesion between SPC and PLA in the subsequent processing. The result showed excellent mechanical properties and improved thermal properties of PLA/SPC blends. Using processing aids is an effective way to decrease processing temperature and thermal degradation

  19. Effects of lipids and oleic acid on biomass development in anaerobic fixed-bed reactors. Part II : oleic acid toxicity and biodegradability

    OpenAIRE

    Alves, M.M.; Vieira, J. A. Mota; Pereira, R. M. Álvares; M. A. PEREIRA; Mota, M.

    2001-01-01

    Oleic acid toxicity and biodegradability were followed during long-term operation of two similar anaerobic fixed-bed units. When treating an oleate based effluent, the sludge from the bioreactor that was acclimated with lipids during the first operation period, showed a higher tolerance to oleic acid toxicity (IC50=137 mg/l) compared with the sludge fed with a non-fat substrate (IC50=80 mg/l). This sludge showed also the highest biodegradation capacity of oleic acid, achieving max...

  20. Composite biodegradable biopolymer coatings of silk fibroin - Poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) for biomedical applications

    Science.gov (United States)

    Miroiu, Floralice Marimona; Stefan, Nicolaie; Visan, Anita Ioana; Nita, Cristina; Luculescu, Catalin Romeo; Rasoga, Oana; Socol, Marcela; Zgura, Irina; Cristescu, Rodica; Craciun, Doina; Socol, Gabriel

    2015-11-01

    Composite silk fibroin-poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) (SF-PHBV) biodegradable coatings were grown by Matrix Assisted Pulsed Laser Evaporation on titanium substrates. Their physico-chemical properties and particularly the degradation behavior in simulated body fluid at 37 °C were studied as first step of applicability in local controlled release for tissue regeneration applications. SF and PHBV, natural biopolymers with excellent biocompatibility, but different biodegradability and tensile strength properties, were combined in a composite to improve their properties as coatings for biomedical uses. FTIR analyses showed the stoichiometric transfer from targets to coatings by the presence in the spectra of the main absorption maxima characteristic of both polymers. XRD investigations confirmed the FTIR results showing differences in crystallization behavior with respect to the SF and PHBV content. Contact angle values obtained through wettability measurements indicated the MAPLE deposited coatings were highly hydrophilic; surfaces turning hydrophobic with the increase of the PHBV component. Degradation assays proved that higher PHBV contents resulted in enhanced resistance and a slower degradation rate of composite coatings in SBF. Distinct drug-release schemes could be obtained by adjusting the SF:PHBV ratio to controllably tuning the coatings degradation rate, from rapid-release formulas, where SF predominates, to prolonged sustained ones, for larger PHBV content.

  1. Biodegradation of poly(hydroxy butanoic acid) copolymer mulch films in soil

    Science.gov (United States)

    Kukade, Pranav

    Agricultural mulch films that are used to cover soil of crop rows contribute to earlier maturation of crops and higher yield. Incineration and landfill disposals are the most common means of disposal of the incumbent polyethylene (PE) mulch films; however, these are not environment friendly options. Biodegradable mulch films that can be rototilled into the soil after crop harvest are a promising alternative to offset problems such as landfill disposal, film retrieval and disposal costs. In this study, an in-house laboratory scale test method was developed in which the rate of disintegration, as a result of biodegradation of films based on polyhydroxybutanoic acid (PHB) copolymers was investigated in a soil environment using the residual weight loss method. The influence of soil composition, moisture levels in the soil, and industry-standard anti-microbial additive in the film composition on the rate of disintegration of PHB copolymer films was investigated. The soil composition has significant effect on the disintegration kinetics of PHB copolymer films, since the increasing compost levels in the soil lowered the rate of disintegration of the film. Also, with the increase in moisture level up to a threshold limit, the microbial activity and, hence, the rate of disintegration increased. Lastly, the developed lab-scale test protocol was found to be sensitive to even small concentrations of industry-standard antimicrobial additive in the film composition.

  2. Biodegradability of poly (L-lactic acid) functionally graded materials with hardness gradient

    International Nuclear Information System (INIS)

    The aim of this study is to develop a functionally graded material (FGM) of biodegradable poly (L-lactic acid) (PLLA) with a hardness gradient. For this purpose, the PLLA was extruded at elevated temperatures to introduce molecular orientation. Two types of extrusion, direct extrusion and equal channel angular (ECA) extrusion, were carried out. Heat treatment without extrusion was also carried out at 50degC, 60degC and 70degC. For the mechanical property characterization, the hardness distributions were investigated using a Vickers microhardness tester. Biodegradability of PLLA FGM was measured by evaluating the mass decreasing ratio after incubation in a physiological saline solution at 37degC. It was found that the PLLA FGMs with symmetric and asymmetric hardness gradients could be fabricated by direct extrusion and ECA extrusion at elevated temperature, respectively. Although in the initial state the mass of PLLA gradually increased with the softening of the FGM, it started to decrease after two weeks. (author)

  3. A ferulic acid (FA)-eluting system for biodegradable magnesium stent: Cells response of HUVECs.

    Science.gov (United States)

    Zhang, Erlin; Shen, Feng

    2015-08-01

    A new drug-eluting system was designed for biodegradable magnesium stents, in which ferulic acid (FA) was used as drug due to its promotion function to endothelial cells and PHBHHx as drug delivery due to its biodegradability and biocompatibility. A 5 and 10% FA were added in PHBHHx to prepare FA containing PHBHHX films. The cell adhesion, spreading and proliferation on these films was investigated in order to assess cell response of HUVECs. It was also found that FA enhanced the adhesion, spreading and proliferation of HUVECs in a dose-dependent manner. Cell viability after H2 O2 injury and NO production of HUVECs were also studied. The results indicated that FA effectively inhibited H2 O2 -induced injury and promotes NO production. It was also shown that alkali treatment improved the cell adhesion, spreading and proliferation while the treatment reduces the FA release and in turn reduces the inhibition on H2 O2 -induced injury and NO production. However, alkali treatment itself had no influence on the H2 O2 induced injure and NO production. The tensile shear strength between the FA containing coating and Mg substrate was also tested. All results demonstrated that FA containing PHBHHx films exhibited strong promotion to the endothelialization and could be a choice for surface modification of magnesium stent. PMID:25630748

  4. Bio-Based Polymers with Potential for Biodegradability

    Directory of Open Access Journals (Sweden)

    Thomas F. Garrison

    2016-07-01

    Full Text Available A variety of renewable starting materials, such as sugars and polysaccharides, vegetable oils, lignin, pine resin derivatives, and proteins, have so far been investigated for the preparation of bio-based polymers. Among the various sources of bio-based feedstock, vegetable oils are one of the most widely used starting materials in the polymer industry due to their easy availability, low toxicity, and relative low cost. Another bio-based plastic of great interest is poly(lactic acid (PLA, widely used in multiple commercial applications nowadays. There is an intrinsic expectation that bio-based polymers are also biodegradable, but in reality there is no guarantee that polymers prepared from biorenewable feedstock exhibit significant or relevant biodegradability. Biodegradability studies are therefore crucial in order to assess the long-term environmental impact of such materials. This review presents a brief overview of the different classes of bio-based polymers, with a strong focus on vegetable oil-derived resins and PLA. An entire section is dedicated to a discussion of the literature addressing the biodegradability of bio-based polymers.

  5. Biodegradable polyester films from renewable aleuritic acid: surface modifications induced by melt-polycondensation in air

    Science.gov (United States)

    Jesús Benítez, José; Alejandro Heredia-Guerrero, José; Inmaculada de Vargas-Parody, María; Cruz-Carrillo, Miguel Antonio; Morales-Flórez, Victor; de la Rosa-Fox, Nicolás; Heredia, Antonio

    2016-05-01

    Good water barrier properties and biocompatibility of long-chain biopolyesters like cutin and suberin have inspired the design of synthetic mimetic materials. Most of these biopolymers are made from esterified mid-chain functionalized ω-long chain hydroxyacids. Aleuritic (9,10,16-trihydroxypalmitic) acid is such a polyhydroxylated fatty acid and is also the major constituent of natural lac resin, a relatively abundant and renewable resource. Insoluble and thermostable films have been prepared from aleuritic acid by melt-condensation polymerization in air without catalysts, an easy and attractive procedure for large scale production. Intended to be used as a protective coating, the barrier's performance is expected to be conditioned by physical and chemical modifications induced by oxygen on the air-exposed side. Hence, the chemical composition, texture, mechanical behavior, hydrophobicity, chemical resistance and biodegradation of the film surface have been studied by attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR), atomic force microscopy (AFM), nanoindentation and water contact angle (WCA). It has been demonstrated that the occurrence of side oxidation reactions conditions the surface physical and chemical properties of these polyhydroxyester films. Additionally, the addition of palmitic acid to reduce the presence of hydrophilic free hydroxyl groups was found to have a strong influence on these parameters.

  6. 微波辅助聚乳酸合成的研究进展%Research Progress on Microwave-assisted Poly(Lactic Acid) Synthesis

    Institute of Scientific and Technical Information of China (English)

    孙正谦; 郑红娟

    2016-01-01

    Poly lactic acid is a new type of complete biodegradable green plastic. Microwave irradiation, which is compared with the traditional heating method during the synthesis, has the advantages of high efficiency, energy saving and reduce cost, etc. The active principle of microwave, the process of synthesizing lactic in two different ways ( direct polymerization and lactate lactic ring-opening polymerization) , and the influence of temperature, power, reaction time, vacuum degree, catalyst were discussed. This review dealt with the recent progress in microwave-assisted synthesis of PLA, and made expectation about the development way in the future.%聚乳酸是一种完全生物可降解的新型绿色塑料。在聚乳酸的合成过程中,微波辐射加热相比传统加热具有高效节能、降低成本等优点。本文具体介绍了微波作用原理,以及在微波辐射的条件下,两种不同合成工艺(直接聚合法和开环聚合法)的具体内容,反应过程中温度、功率、反应时间、真空度、催化剂种类及用量等工艺参数,综述了微波在聚乳酸合成方面研究的最新进展,并对其未来前景做出了展望。

  7. Paclitaxel loaded biodegradable poly (sebacic acid-co-ricinoleic acid cylindrical implants for local delivery-in vitro characterization

    Directory of Open Access Journals (Sweden)

    Jagadeesh G Hiremath

    2013-01-01

    Full Text Available The aim of the present research work was to develop the biodegradable polymeric implant for the delivery of antineoplastic drug, paclitaxel (PTX using poly (sebacic-co-recinoleic acid 70:30 w/w. PTX loaded implants were prepared by indigenously developed melt molding technique. Implants were characterized in terms of physico-chemical evaluations, drug content, drug stability and intactness, thermal analysis, drug physical state and crystallinity, surface morphology, hydrolytic degradation, drug release and its kinetics. Prepared implants were yellow and cylindrical in shape with smooth surfaces. Drug in the implants was found to be stable, intact and uniformly dispersed as amorphous state within the polymer matrix. In vitro release, kinetic studies showed zero order and Korsmeyer-Peppas model release being exhibited. Drug release from the polymeric implants was occurred could be as results of diffusion.

  8. PREPARATION AND CELL COMPATIBILITY OF FUNCTIONALIZED BIODEGRADABLE POLY(DL-LACTIDE-CO-RS-Β-MALIC ACID)

    Institute of Scientific and Technical Information of China (English)

    Kui-lin Lai; Bin He; Zhong-wei Gu

    2008-01-01

    In order to create a functionalized biodegradable polymer for vascular tissue engineering application, poly(DL-lactide-co-RS-β-malic acid) (PDLLMAc) was synthesized. PDLLMAc was obtained after hydrogenolysis of poly(DL-lactide-co-RS-β-benzyl malolactonate) (PDLLMA), which was from the ring-opening polymerization of DL-lactide (DLLA)and RS-β-benzyl malolactonate (MA) using stannous octoate as catalyst. The copolymers were characterized by 1H-NMR,FTIR, GPC and DSC. The tensile strength and water uptake of the copolymers were measured. In copolymerization, theproportion of MA in the derived copolymers was lower than that in the feeding dose, a consequence of its lower reactivity.The molecular weight of the copolymers decreased with increasing MA content. The protective benzyl groups werecompletely removed in hydrogenolysis. The glass transition temperature (Tg) of the protected copolymers decreased withincreasing MA content. The mechanical strength test showed that the tensile strength of PDLLMA decreased whileelongation increased with MA content increasing, and the tensile strength increased and elongation decreased with increasingmalic acid content in PDLLMAc for the formation of hydrogen bonding. The water uptake showed that more hydrophilicmalic acid adsorbed more water in PDLLMAc. In order to test the reactivity of functional pendant groups, bioactive RGDpeptide was immobilized on the functionalized polymer film surface and smooth muscle cells (SMCs) were cultured on it.The results showed that the functionalized copolymer was biocompatible and could be potentially applied in vascular tissueengineering.

  9. A two-stage anaerobic system for biodegrading wastewater containing terephthalic acid and high strength easily degradable pollutants

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The high strength easily biodegradable pollutants(represented by CODE) are strong inhibitors of terephthalic acid(TA) anaerobic biodegradation. At the same time, TA can inhibiteasily biodegradable pollutants removal under anaerobic conditionsto a limited extent. This mutual inhibition could happen and causea low removal efficiency of both TA and CODE, when the effluentfrom TA workshops containing TA and easily biodegradable pollutantsare treated by a single anaerobic reactor system. Based upon thetreatment kinetics analysis of both TA degradation and CODEremoval, a two-stage up-flow anaerobic sludge blanket and up-flowfixed film reactor(UASB-UAFF) system for dealing with this kind ofwastewater was developed and run successfully at laboratory scale.An UASB reactor with the methanogenic consortium as the first stageremoves the easily biodegradable pollutants(CODE). An UAFF reactor as the second stage is mainly in charge of TA degradation. At aHRT 18.5h, the CODE and TA removal rate of the system reached 89.2% and 71.6%, respectively.

  10. Stability studies of a somatostatin analogue in biodegradable implants.

    Science.gov (United States)

    Rothen-Weinhold, A; Besseghir, K; Vuaridel, E; Sublet, E; Oudry, N; Gurny, R

    1999-02-15

    In recent years, peptides and proteins have received much attention as drug candidates. For many polypeptides, particularly hormones, it is desirable to release the drug continuously at a controlled rate over a period of weeks or even months, and thus a controlled release system is needed. Polylactic acid (PLA) is a biocompatible and biodegradable material with wide utility for many applications, including the design of controlled release systems for pharmaceutical agents. Pharmaceutical development of these delivery systems presents new problems in the area of stability assessment, especially for peptide drugs. In this study, we aimed to investigate the influence of different steps, during the manufacturing of an implant, on peptide stability in the polymeric matrix. Polylactic acid implants containing vapreotide, a somatostatin analogue, were prepared by extrusion. The effects of time, extrusion and temperature on the peptide stability were studied. The influence of various gamma sterilization doses, as well as the conditions under which the implants were irradiated, were also investigated. Peptide stability in the polymeric matrix was evaluated at various temperatures and at various time intervals up to 9 months. PMID:10205641

  11. Screening of microorganisms for biodegradation of poly(lactic-acid) and lactic acid-containing polymers.

    OpenAIRE

    Torres, A.; Li, S.M.; S. Roussos; Vert, M.

    1996-01-01

    The ability of some microorganisms to use lactic acid stereocopolymers and copolymers with glycolic acid as sole carbon and energy sources was studied under controlled or natural conditions. First, 14 filamentous fungal strains were tested in liquid cultures, adopting total lactic acid consumption, nitrogen source exhaustion, and maximal biomass production as selection criteria. Two strains of #Fusarium moniliforme$ and one strain of #Penicillium roqueforti$ were able to totally assimilate DL...

  12. Biodegradable microsphere-mediated cell perforation in microfluidic channel using femtosecond laser

    Science.gov (United States)

    Ishii, Atsuhiro; Ariyasu, Kazumasa; Mitsuhashi, Tatsuki; Heinemann, Dag; Heisterkamp, Alexander; Terakawa, Mitsuhiro

    2016-05-01

    The use of small particles has expanded the capability of ultrashort pulsed laser optoinjection technology toward simultaneous treatment of multiple cells. The microfluidic platform is one of the attractive systems that has obtained synergy with laser-based technology for cell manipulation, including optoinjection. We have demonstrated the delivery of molecules into suspended-flowing cells in a microfluidic channel by using biodegradable polymer microspheres and a near-infrared femtosecond laser pulse. The use of polylactic-co-glycolic acid microspheres realized not only a higher optoinjection ratio compared to that with polylactic acid microspheres but also avoids optical damage to the microfluidic chip, which is attributable to its higher optical intensity enhancement at the localized spot under a microsphere. Interestingly, optoinjection ratios to nucleus showed a difference for adhered cells and suspended cells. The use of biodegradable polymer microspheres provides high throughput optoinjection; i.e., multiple cells can be treated in a short time, which is promising for various applications in cell analysis, drug delivery, and ex vivo gene transfection to bone marrow cells and stem cells without concerns about residual microspheres.

  13. Poly-γ-Glutamic Acid: Biodegradable Polymer for Potential Protection of Beneficial Viruses

    Directory of Open Access Journals (Sweden)

    Ibrahim R. Khalil

    2016-01-01

    Full Text Available Poly-γ-glutamic acid (γ-PGA is a naturally occurring polymer, which due to its biodegradable, non-toxic and non-immunogenic properties has been used successfully in the food, medical and wastewater industries. A major hurdle in bacteriophage application is the inability of phage to persist for extended periods in the environment due to their susceptibility to environmental factors such as temperature, sunlight, desiccation and irradiation. Thus, the aim of this study was to protect useful phage from the harmful effect of these environmental factors using the γ-PGA biodegradable polymer. In addition, the association between γ-PGA and phage was investigated. Formulated phage (with 1% γ-PGA and non-formulated phage were exposed to 50 °C. A clear difference was noticed as viability of non-formulated phage was reduced to 21% at log10 1.3 PFU/mL, while phage formulated with γ-PGA was 84% at log10 5.2 PFU/mL after 24 h of exposure. In addition, formulated phage remained viable at log10 2.5 PFU/mL even after 24 h of exposure at pH 3 solution. In contrast, non-formulated phages were totally inactivated after the same time of exposure. In addition, non-formulated phages when exposed to UV irradiation died within 10 min. In contrast also phages formulated with 1% γ-PGA had a viability of log10 4.1 PFU/mL at the same exposure time. Microscopy showed a clear interaction between γ-PGA and phages. In conclusion, the results suggest that γ-PGA has an unique protective effect on phage particles.

  14. Biodegradation of dimethyl phthalate by Sphingomonas sp. isolated from phthalic-acid-degrading aerobic granules.

    Science.gov (United States)

    Zeng, Ping; Moy, Benjamin Yan-Pui; Song, Yong-Hui; Tay, Joo-Hwa

    2008-10-01

    Phthalic acid esters (PAEs) contamination in water, air, and soil is one of the major environmental concerns in many countries. Besides the PAE biodegradation process, the PAE degrading bacteria have become one of the focuses of study. This study reports the successful isolation of one kind of indigenous bacterium PA-02 from phthalic acid (PA)-degrading aerobic granules. Based on its 16S ribosomal DNA sequence, isolate PA-02 was identified as Sphingomonas genus with 100% similarity to Sphingomonas sp. strain D84532. Strain PA-02 was a Gram-negative, rod-shaped bacterium with strong auto-aggregation ability. In particular, the strain PA-02 possessed PAE-degrading ability without acclimation. Results of growth tests showed that strain PA-02 could degrade dimethyl phthalate (DMP), dibutyl phthalate, and diethylhexyl phthalate. The specific degradation rates of DMP and PA were concentration-dependent with maximum values of 0.4 g-DMP g(-1) biomass h(-1) and 1.3 g-PA g(-1) biomass h(-1), respectively. Kinetic studies also revealed that PA-02 was robust under high concentrations of DMP and PA. Even when the PA concentration was increased to 1,000.0 mg l(-1), the specific PA degradation rate was about 0.25 g-PA g(-1) biomass h(-1). The corresponding value for DMP was 0.067 g-DMP g(-1) biomass h(-1) at 1,000 mg l(-1). PMID:18751698

  15. Development of methodology for the synthesis of poly(lactic acid-co-glycolic acid) for use in the production of radioactive sources

    International Nuclear Information System (INIS)

    According to the World Health Organization, cancer is a leading cause of death worldwide. A radiotherapy method extensively used in prostate cancer is brachytherapy, where the area requiring treatment receives radioactive seeds. Iodine-125 seeds can be inserted loose or stranded in bioabsorbable polymers produced from poly(lactic-co-glycolic acid) (PLGA). We developed the synthesis methodology for PLGA and the results obtained show that it was possible to determine the optimal reaction parameters (time and temperature) for PLGA in 80/20 (lactide/glycolide) ratio. The yield was higher than 90% using a temperature of 110 °C and reaction time of 72 hours; however, the molecular weight values obtained are very low compared to those obtained by other authors. New tests using previously synthesized dimers and nitrogen atmosphere are being performed. These conditions could potentially increase the molar mass of PLGA. All techniques used confirmed the expected structure of the polymer. (author)

  16. Development of methodology for the synthesis of poly(lactic acid-co-glycolic acid) for use in the production of radioactive sources

    International Nuclear Information System (INIS)

    According to World Health Organization (WHO), cancer is a leading cause of death worldwide. Prostate cancer is the second most common cancer in men. A method of radiotherapy which has been extensively used is brachytherapy, where radioactive seeds are placed inside the area requiring treatment. Iodine-125 seeds can be placed loose or stranded in bioabsorbable polymers. Stranded seeds show some advantages, since they reduce the rate of seed migration, an event that could affect the dosimetry of the prostate and cause unnecessary damage to healthy tissues or organs. For Iodine-125 stranded seeds, polyglactin 910 (poly(lactic-co-glycolic acid)) (PLGA), with a coverage of polyglactin 370 (Vicryl ®) is used. It was purposed in this dissertation, the study and development of the synthesis methodology for PLGA via ring-opening polymerization, as well as its characterization, with the objective of using the synthesized material to manufacture a material similar to RAPID Strand®. The results obtained show that it was possible to determine the optimal reaction parameters (time and temperature) for PLGA in 80/20 (lactide/glycolide) ratio. Using a temperature of 110 ° C and reaction time of 24h, a yield of 86% was obtained, and increasing the reaction time to 72 hours, the yield was higher than 90%. The molecular mass values obtained from the samples are still very low compared to those obtained by other authors in the literature (about 20%). Failures in the sealing of vials, leaving them vulnerable to moisture and oxygen, or lack of an efficient stirring system might be possible explanations for these results. A suitable chemical reactor could solve the problem. Regarding polymer characterization, all techniques used not only confirmed the expected structure of the polymer, but also showed the highest proportion of lactide units compared to to glycolide units. (author)

  17. Biodegradable mucus-penetrating nanoparticles composed of diblock copolymers of polyethylene glycol and poly(lactic-co-glycolic acid)

    OpenAIRE

    Yu, Tao; Wang, Ying-Ying; Yang, Ming; Schneider, Craig; Zhong, Weixi; Pulicare, Sarah; Choi, Woo-Jin; Mert, Olcay; Fu, Jie; Lai, Samuel K.; Hanes, Justin

    2012-01-01

    Mucus secretions coating entry points to the human body that are not covered by skin efficiently trap and clear conventional drug carriers, limiting controlled drug delivery at mucosal surfaces. To overcome this challenge, we recently engineered nanoparticles that readily penetrate a variety of human mucus secretions, which we termed mucus-penetrating particles (MPP). Here, we report a new biodegradable MPP formulation based on diblock copolymers of poly(lactic-co-glycolic acid) and poly(ethy...

  18. Design, synthesis and characterization of novel biodegradable macrodiols based on poly(DL-lactic acid) and poly(p-dioxanone)

    Institute of Scientific and Technical Information of China (English)

    Chan Yu Zhang; Yan Feng Luo; Su Jun Wang; Zhao Liu; Yuan Liang Wang; Zhi Qing Liang

    2009-01-01

    Integrating poly(lactic acid) (PLA), glycolic acid (GA) and ethylene glycol (EG) will hopefully result in a novel copolymer that combines such advantages as fastened and controllable release rate and improved flexibility together with good biocompatibility. In this study, p-dioxanone (PDO) was employed to copolymerize with DL-lactide (LA) via ring-opening melt polymerization using Sn(Oct)2 as an initiator and ethylene glycol as a co-initiator. The obtained degradable macrodiols (HO-P(LA-co-PDO)-OH) were just such a copolymer consisting of PLA, GA and EG. 1H NMR was employed to characterize the copolymers, and the effect of PDO/LA molar ratios in the feedstock on the molecular weights of HO-P(LA-co-PDO)-OH was investigated by means of end-hydroxyl analysis, 1H NMR or GPC-MALLs. The results confirmed the successful synthesis of HO-P(LA-co-PDO)-OH and revealed that one end-hydroxyl of the micarodiols was donated by LA or PDO and the other one by the co-initiator EG. In addition,the molecular weights of HO-P(LA-co-PDO)-OH increased with decreasing PDO/LA ratios.

  19. 聚乳酸防粘连凝胶和透明质酸钠在预防术后肠粘连效果中的对比观察%Comparison of polylactic acid anti-adhesion gel and sodium hyaluronate in the prevention of postoperative in-testinal adhesion

    Institute of Scientific and Technical Information of China (English)

    李坤; 刘英姿; 高会聪

    2013-01-01

    目的:对比观察聚乳酸防粘连凝胶和透明质酸钠在预防腹部手术后肠粘连的效果,以指导临床用药。方法根据患者选择抗粘连药物的不同,将患者分为聚乳酸防粘连凝胶组(427例)和透明质酸钠组(429例),于手术结束关腹前,分别涂以聚乳酸防粘连凝胶或透明质酸钠,观察患者术后体温恢复正常所需时间、肠管通气时间以及术后6个月内肠粘连的表现。结果所有患者中,术后均无药物过敏现象出现,无脓肿、肠瘘及其他不良反应发生,术后改善情况良好。观察术后1周患者发热时间、肠鸣音恢复时间、肛门排气时间,聚乳酸防粘连凝胶组均短于透明质酸钠组( P<0.01)。聚乳酸防粘连凝胶组在术后3个月和术后6个月发生肠粘连表现的例数也少于透明质酸钠组( P<0.05)。结论聚乳酸防粘连凝胶和透明质酸钠对腹部手术后预防肠粘连均有明显作用,聚乳酸防粘连凝胶预防粘连效果优于透明质酸钠。%Objective To compare the effects of polylactic acid anti-adhesion gel and sodium hyaluronate in the prevention of postoperative intestinal adhesion , to guide the clinical use of drugs .Methods According to the se-lected anti adhesion drug , the patients were divided into polylactic acid anti-adhesion gel group and sodium hyalur-onate group , and were coated with polylactic acid anti-adhesion gel or sodium hyaluronate on the surgical wound at the end of operation and before closing abdomen .After operation , the time of temperature returning to normal , intestine ventilation time and the intestinal adhesion performance at 6 months after operation were observed .Results In all pa-tients, postoperative improvement was in good condition and no drug allergies , abscess, fistula and other adverse re-actions were found.Observation of postoperative 1 week showed patients′heating time, borborygmus recovery time, anal exhaust

  20. Method for Simultaneously improving the thermal stability and mechanical properties of poly(lactic acid): effect of high-energy electrons on the morphological, mechanical, and thermal properties of PLA/MMT nanocomposites.

    Science.gov (United States)

    Wang, De-Yi; Gohs, Uwe; Kang, Nian-Jun; Leuteritz, Andreas; Boldt, Regine; Wagenknecht, Udo; Heinrich, Gert

    2012-08-28

    Nanocomposites derived from poly(lactic acid) (PLA) and organically modified montmorillonite (oMMT) have been cross-linked by high-energy electrons in the presence of triallyl cyanurate (TAC). The morphology of untreated and cross-linked PLA/MMT nanocomposites was characterized by wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). This treatment can improve both the thermal stability and the glass-transition temperatures of the PLA nanocomposites (e.g., PLA-MMT-TAC 30kGy, 50kGy, and 70kGy) because of the formation of cross-linking structures in the nanocomposites that will considerably reduce the mobility of polymers. Interestingly, at relatively low irradiation doses (e.g., 30 and 50 kGy) a good balance between tensile strength and elongation at break for the PLA nanocomposites could be achieved. These mechanical properties are superior to those of pure PLA. Therefore, combining nanotechnology and electron beam cross-linking is a promising new method of simultaneously improving the mechanical properties (toughness and tensile strength) and thermal stability of PLA. PMID:22845883

  1. 聚乳酸/木粉复合材料的制备与力学性能研究%Study on Mechanical Properties of Poly(lactic acid)/Wood Powder Composites and Its Preparation

    Institute of Scientific and Technical Information of China (English)

    陈良壁; 温荣伟; 林权; 刘瑞来

    2012-01-01

    Selecting PLA as matrix resin and wood powder as filler, Poly(lactic acid)/wood powder composites were prepared by hot-forming molding and injection molding. The results show that: with increasing of wood powder content from 20% to 60%, the tensile strength of PLA/wood powder composites decreases from 41.83 MPa to 15.96 MPa, the modulus of elasticity decreases from 1 035.96 MPa to 283.43 MPa, and elongation at break decreases from 7.04% to 1.73%.%以聚乳酸(PLA)为基体,木粉为填料,分别采用热压成型和注塑成型方法制备了PLA/术粉复合材料.实验研究结果表明:当木粉用量由20%增加到60%时,PLA/木粉复合材料的拉伸强度由41.83 MPa降至15.96MPa;弹性模量由1 035.96 MPa降至283.43 MPa,断裂伸长率由7.04%降至1.73%.

  2. Poly(Dopamine-Assisted Immobilization of Xu Duan on 3D Printed Poly(Lactic Acid Scaffolds to Up-Regulate Osteogenic and Angiogenic Markers of Bone Marrow Stem Cells

    Directory of Open Access Journals (Sweden)

    Chia-Hung Yeh

    2015-07-01

    Full Text Available Three-dimensional 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 and Xu Duan (XD immobilization to regulate cell adhesion, proliferation and differentiation of human bone-marrow mesenchymal stem cells (hBMSCs. We prepared PLA scaffolds and coated with polydopamine (PDA. The chemical composition and surface properties of PLA/PDA/XD were characterized by XPS. PLA/PDA/XD controlled hBMSCs’ responses in several ways. Firstly, adhesion and proliferation of hBMSCs cultured on PLA/PDA/XD were significantly enhanced relative to those on PLA. In addition, the focal adhesion kinase (FAK expression of cells was increased and promoted cell attachment depended on the XD content. In osteogenesis assay, the osteogenesis markers of hBMSCs cultured on PLA/PDA/XD were significantly higher than seen in those cultured on a pure PLA/PDA scaffolds. Moreover, hBMSCs cultured on PLA/PDA/XD 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 hBMSCs.

  3. True mechanical behavior and the associated structure morphology of poly(lactic acid) polymer in strain induced crystallization by in-situ time resolved X-ray diffraction and scattering technique

    International Nuclear Information System (INIS)

    Changes in molecular structure configuration during strain induced crystallisation of an amorphous Poly(Lactic Acid) (PLA 4032D) polymer was monitored in-situ by simultaneously recording the wide angle x-ray scattering (WAXS) and small angle x-ray scattering (SAXS) patterns together with polymer deformation images and force data. The amorphous chain orientation from the beginning of deformation until the onset of crystallisation was studied from the WAXS patterns. The true mechanical behaviour described by the true stress-true strain curve related to an amorphous chain orientation exhibited a linear behaviour. Approaching critical amorphous orientation, the true stress-true strain curve deviated from linear into non-linear behaviour. After the onset of crystallization, when the deformed polymer became a semicrystalline state, the true mechanical behaviour exhibited true strain hardening which greatly affected by the formation of the morphology. The gradual true strain hardening was associated with the formation of micro-fibrillar structure containing thin crystallite morphology whilst sharp increased in true strain hardening was associated with the formation of stacked lamellar morphology in the form of macro-lattice structure. The study was accomplished by the application of high brilliance synchrotron radiation at beamline ID2 of ESRF, Grenoble in France and the usage of the high contrast resolution of WAXS and SAXS charge-couple device (CCD) camera as well as 40 milliseconds temporal resolution of data acquisition system. (author)

  4. Effects of lipids and oleic acid on biomass development in anaerobic fixed-bed reactors. Part II: Oleic acid toxicity and biodegradability.

    Science.gov (United States)

    Alves, M M; Vieira, J A; Pereira, R M; Pereira, M A; Mota, M

    2001-01-01

    Oleic acid toxicity and biodegradability were followed during long-term operation of two similar anaerobic fixed-bed units. When treating an oleate based effluent, the sludge from the bioreactor that was acclimated with lipids during the first operation period, showed a higher tolerance to oleic acid toxicity (IC50 = 137 mg/l) compared with the sludge fed with a non-fat substrate (IC50 = 80 mg/l). This sludge showed also the highest biodegradation capacity of oleic acid, achieving maximum methane production rates between 33 and 46 mlCH4(STP)/gVS.day and maximum percentages of methanization between 85 and 98% for the range of concentrations between 500 and 900 mg oleate/l. When oleate was the sole carbon source fed to both digesters, the biomass became encapsulated with organic matter, possibly oleate or an intermediate of its degradation, e.g. stearate that was degraded at a maximum rate of 99 mlCH4(STP)/gVS.day. This suggests the possibility of using adsorption-degradation cycles for the treatment of LCFA based effluents. Both tolerance to toxicity and biodegradability of oleic acid were improved by acclimatization with lipids or oleate below a threshold concentration. PMID:11257881

  5. Small (13)C/(12)C fractionation contrasts with large enantiomer fractionation in aerobic biodegradation of phenoxy acids.

    Science.gov (United States)

    Qiu, Shiran; Gözdereliler, Erkin; Weyrauch, Philip; Lopez, Eva C Magana; Kohler, Hans-Peter E; Sørensen, Sebastian R; Meckenstock, Rainer U; Elsner, Martin

    2014-05-20

    Phenoxy acid herbicides are important groundwater contaminants. Stable isotope analysis and enantiomer analysis are well-recognized approaches for assessing in situ biodegradation in the field. In an aerobic degradation survey with six phenoxyacetic acid and three phenoxypropionic acid-degrading bacteria we measured (a) enantiomer-specific carbon isotope fractionation of MCPP ((R,S)-2-(4-chloro-2-methylphenoxy)-propionic acid), DCPP ((R,S)-2-(2,4-dichlorophenoxy)-propionic acid), and 4-CPP ((R,S)-2-(4-chlorophenoxy)-propionic acid); (b) compound-specific isotope fractionation of MCPA (4-chloro-2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid); and (c) enantiomer fractionation of MCPP, DCPP, and 4-CPP. Insignificant or very slight (ε = -1.3‰ to -2.0‰) carbon isotope fractionation was observed. Equally small values in an RdpA enzyme assay (εea = -1.0 ± 0.1‰) and even smaller fractionation in whole cell experiments of the host organism Sphingobium herbicidovorans MH (εwc = -0.3 ± 0.1‰) suggest that (i) enzyme-associated isotope effects were already small, yet (ii) further masked by active transport through the cell membrane. In contrast, enantiomer fractionation in MCPP, DCPP, and 4-CPP was pronounced, with enantioselectivities (ES) of -0.65 to -0.98 with Sphingomonas sp. PM2, -0.63 to -0.89 with Sphingobium herbicidovorans MH, and 0.74 to 0.97 with Delftia acidovorans MC1. To detect aerobic biodegradation of phenoxypropionic acids in the field, enantiomer fractionation seems, therefore, a stronger indicator than carbon isotope fractionation. PMID:24708181

  6. Improved Biocompatibility of Novel Biodegradable Scaffold Composed of Poly-L-lactic Acid and Amorphous Calcium Phosphate Nanoparticles in Porcine Coronary Artery

    OpenAIRE

    Dongsheng Gu; Gaoke Feng; Guanyang Kang; Xiaoxin Zheng; Yuying Bi; Shihang Wang; Jingyao Fan; Jinxi Xia; Zhimin Wang; Zhicheng Huo; Qun Wang; Tim Wu; Xuejun Jiang; Weiwang Gu; Jianmin Xiao

    2016-01-01

    Using poly-L-lactic acid for implantable biodegradable scaffold has potential biocompatibility issue due to its acidic degradation byproducts. We have previously reported that the addition of amorphous calcium phosphate improved poly-L-lactic acid coating biocompatibility. In the present study, poly-L-lactic acid and poly-L-lactic acid/amorphous calcium phosphate scaffolds were implanted in pig coronary arteries for 28 days. At the follow-up angiographic evaluation, no case of stent thrombosi...

  7. 甲壳素神经再生室注入聚乳酸-聚乙醇酸-重组人促红细胞生成素微球促进缺损周围神经的修复%Injection of polylactic acid-polyglycolic acid-recombinant human erythropoietin microspheres into chitin nerve regeneration chamber can promote sciatic nerve regeneration

    Institute of Scientific and Technical Information of China (English)

    黄亚洲; 陈清汉; 任明明

    2012-01-01

    背景:促红细胞生成素除了具有造血的作用以外,对神经系统损伤的修复也起着重要作用.目的:观察聚乳酸-聚乙醇酸-重组人促红细胞生成素微球对大鼠坐骨神经再生的作用.方法:雌性SD大鼠60只,随机分为3组.制备大鼠双侧坐骨神经缺损模型(1 cm缺损)以及可吸收甲壳素神经再生室.实验组室内注入聚乳酸-聚乙醇酸-重组人促红细胞生成素微球;对照组室内注入聚乳酸-聚乙醇酸微球;空白对照组室内注入等渗生理盐水.结果与结论:实验组再生神经的传导速度优于对照组及空白对照组,且12周优于6周,差异有显著性意义(P < 0.05).S-100 免疫组织化学及Loyez氏神经染色法显示:实验组神经纤维数量多于对照组及空白对照组,12周多于6周,差异有显著性意义(P < 0.05).结果提示聚乳酸-聚乙醇酸-重组人促红细胞生成素微球能够促进实验性坐骨神经缺损的再生和功能的恢复.%BACKGROUND: Erythropoietin (EPO) plays an important role in hematopoiesis as well as in the repair of nervous system injury. OBJECTIVE: To observe the effect of polylactic acid-polyglycolic acid-recombinant human erythropoietin microspheres on sciatic nerve regeneration. METHODS: Sixty female SD rats were randomly divided into three groups, 20 rats in each group. The bilateral sciatic nerve defect model was prepared (1 cm defect) and the absorbable chitin nerve regeneration chamber was prepared. The chambers of the rats in the experimental group were injected with polylactic acid-polyglycolic acid-recombinant human erythropoietin microspheres, chambers of the rats in the control group were injected with polylactic acid-polyglycolic acid microspheres and chambers of the rats in the blank control group were injected with normal saline in the same dose. RESULTS AND CONCLUSION: The conduction velocity of the regeneration nerve in the experimental group was better than that in the control group and

  8. Orthopaedic applications for PLA-PGA biodegradable polymers.

    Science.gov (United States)

    Athanasiou, K A; Agrawal, C M; Barber, F A; Burkhart, S S

    1998-10-01

    Biodegradable polymers, especially those belonging to the family of polylactic acid (PLA) and polyglycolic acid (PGA), play an increasingly important role in orthopaedics. These polymers degrade by hydrolysis and enzymatic activity and have a range of mechanical and physical properties that can be engineered appropriately to suit a particular application. Their degradation characteristics depend on several parameters including their molecular structure, crystallinity, and copolymer ratio. These biomaterials are also rapidly gaining recognition in the fledging field of tissue engineering because they can be fashioned into porous scaffolds or carriers of cells, extracellular matrix components, and bioactive agents. Although their future appears to be bright, several questions regarding the biocompatibility of these materials linger and should be addressed before their wide-scale use. In the context of musculoskeletal tissue, this report provides a comprehensive review of properties and applications of biodegradable PLA/PGA polymers and their copolymers. Of special interest are orthopaedic applications, biocompatibility studies, and issues of sterilization and storage of these versatile biomaterials. Also discussed is the fact that terms such as PLA, PGA, or PLA-PGA do not denote one material, but rather a large family of materials that have a wide range of differing bioengineering properties and concomitant biological responses. An analysis of some misconceptions, problems, and potential solutions is also provided. PMID:9788368

  9. 胶原改良聚乳酸电纺丝支架用于组织工程化输尿管的体外构建%A modified electrospun polylactic acid/collagen scaffold for ureteral tissue engineering reconstruction in vitro

    Institute of Scientific and Technical Information of China (English)

    许永德; 符伟军; 史建国; 谭海颂; 张旭

    2012-01-01

    BACKGROUND: Polylactic acid is a widely used scaffold material, but its hydrophobicity and lack of cell recognition signal limit its application. OBJECTIVE: To investigate the feasibility of constructing a tissue engineered ureter using a modified polylactic acid/typeⅠ collagen compound scaffold in vitro. METHODS: Electrospinning polylactic acid naofibrous scaffolds were dipped into a acetic acid solution of type- collagen to Ⅰmake the collagen absorbed onto the nanofiber surface. Then ureter epithelial cells were seeded separately onto the modified electrospun polylactic acid naofibrous scaffolds or control scaffolds. RESULTS AND CONCLUSION: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay results confirmed that there was higher cellular activity in the collagen modified compound scaffolds, which was superior to cells untreated electrospinning polylactic acid scaffold at each time point. Scanning electron microscope showed that the most part of the surface of the modified scaffold was covered with ureter epithelial cells at 5 days after seeding. The modified polylactic acid/type collagen compound scaffold can obviously increase adhesion, growth and proliferation of the seeded cells, and has potential applications in ureteral tissue engineering reconstruction.%背景:聚乳酸是一种应用广泛的细胞支架材料,但其疏水性和缺乏细胞识别信号影响了在组织工程器官构建中的应用.目的:探讨Ⅰ型胶原蛋白改良聚乳酸电纺丝支架体外构建组织工程化输尿管的可行性.方法:用Ⅰ型胶原蛋白醋酸溶液冻干法处理聚乳酸电纺丝,使Ⅰ型胶原蛋白吸附于电纺丝纤维表面,制成胶原改良电纺丝支架.将分离培养的输尿管上皮细胞分别接种于改良聚乳酸电纺丝支架和未处理的聚乳酸电纺丝支架上.结果与结论:MTT检测显示输尿管上皮细胞在改良支架中生长良好,细胞整体活性在各时间点均明显优于未处理的聚

  10. 氯苯甲酸生物降解及环境影响研究进展%Review on Chlorobenzoic Acids Biodegradation and Their Environmental Impacts

    Institute of Scientific and Technical Information of China (English)

    吕文明

    2005-01-01

    Chlorobenzoic Acids are toxic organic compounds largely distributed in soils and sediments. They can be degraded to various products by microorgans. This paper is a review of the literature on biodegradability of the chlorobenzoic acids. The degradation pathways, degradation genes, role of transposable elements, and construction of strains are discussed. A brief introduction is given on the environmental impacts and the pollution control.

  11. Biomechanical stability of a bioabsorbable self-retaining polylactic acid/nano-sized β-tricalcium phosphate cervical spine interbody fusion device in single-level anterior cervical discectomy and fusion sheep models

    Directory of Open Access Journals (Sweden)

    Cao L

    2012-11-01

    Full Text Available Lu Cao,1 Ping-Guo Duan,1 Xi-Lei Li,1 Feng-Lai Yuan,3 Ming-Dong Zhao,2 Wu Che,1 Hui-Ren Wang,1 Jian Dong11Department of Orthopedic Surgery, Zhongshan Hospital, State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, China; 2Department of Orthopedic Surgery, Jinshan Hospital, Fudan University, Shanghai, China; 3Affiliated Third Hospital of Nantong University, Wuxi, ChinaPurpose: The aim of this study was to investigate the biomechanical stability provided by a novel, polylactic acid/nano-sized, β-tricalcium phosphate, bioabsorbable, self-retaining cervical fusion cage (BCFC.Methods: Quasistatic nonconstraining torques (maximum 1.5 NM induced flexion, extension, lateral bending (±1.5 NM, and axial rotation (±1.5 NM on 32 sheep cervical spines (C2–C5. The motion segment C3–C4 was first tested intact; the following groups were tested after complete discectomy: autologous tricortical iliac crest bone graft, Medtronic–Wego polyetheretherketone (PEEK cage, Solis PEEK cage, and BCFC. The autologous bone graft group was tested with an anterior plate. The mean range of motion (ROM was calculated from the load-displacement curves.Results: BCFC significantly decreased ROM in lateral bending and axial rotation compared to other implants, and no significant difference in ROM between two types of PEEK cages and BCFC could be observed in flexion and extension. Anterior cervical plate (ACP significantly decreased ROM in flexion and extension, but no significant difference in ROM between BCFC and bone graft plus ACP could be determined in lateral bending and axial rotation.Conclusion: The BCFC device showed better stability to autologous tricortical iliac crest bone graft and PEEK cages in single-level anterior cervical discectomy and fusion models and thus may be a potential alternative to the current PEEK cages.Keywords: biomechanics, cervical spine, cages, bioabsorbable, sheep

  12. 用于3D打印的改性聚乳酸丝材的制备与研究%Preparation and Study of Modiifed Polylactic Acid Filament for 3D Printing

    Institute of Scientific and Technical Information of China (English)

    陈卫; 汪艳; 傅轶

    2015-01-01

    以聚乳酸(PLA)为基材,Joncryl ADR 4370S为扩链剂,采用熔融共混工艺制备了改性PLA,并通过熔融挤出制得用于3D打印的PLA丝材.研究了ADR扩链剂对PLA热性能、熔体强度、力学性能的影响.结果表明,ADR扩链剂提高了PLA的耐热性和熔体强度;相比纯PLA,改性PLA的力学性能有所提高,当ADR用量为0.4%时,改性PLA的力学性能最佳.采用熔融沉积成型桌面3D打印机测试了PLA丝材的打印效果,结果表明,ADR用量为0.4%时,改性PLA丝材的综合打印性能最好.%Modified polylactic acid(PLA) which used PLA as resin matrix and Joncryl ADR 4370S as chain extender was prepared by melt blending,and after melt extrusion,PLA filament which used for 3D printing was prepared.The effects of ADR chain extender on thermal properties,melt strength and mechanical properties of PLA were studied.The results show that ADR chain extender improves the heat resistance and melt strength of PLA.The mechanical properties of modified PLA are somewhat increased compared with pure PLA,when the ratio of ADR achieves 0.4%,mechanical properties of modified PLA were the best.Printing results of PLA filament tested by FDM desktop-level 3D printer shows that when the ratio of ADR is 0.4%,the comprehensive printing performance of modified PLA filament is the best.

  13. Amniotic epithelial stem cell biocompatibility for electrospun poly(lactide-co-glycolide), poly(ε-caprolactone), poly(lactic acid) scaffolds.

    Science.gov (United States)

    Russo, Valentina; Tammaro, Loredana; Di Marcantonio, Lisa; Sorrentino, Andrea; Ancora, Massimo; Valbonetti, Luca; Turriani, Maura; Martelli, Alessandra; Cammà, Cesare; Barboni, Barbara

    2016-12-01

    Three biodegradable thermoplastic polymers, poly(ε-caprolactone) (PCL), poly(l-lactide-co-d,l-lactide) (PLA) and poly(l-lactide-co-glycolide) (PLGA), have been used to produce nonwovens scaffolds with uniform micrometer fibres. Scaffolds' physical and morphological characterization was performed by X-ray diffraction, Scanning Electron Microscopy and Contact-Angle test. Morphological investigations revealed that all produced fibres were randomly orientated with interconnected pores ranging between 5 and 12μm in diameter. An average fibre diameter of 1.5, 0.75 and 1.2μm was found for PCL, PLA and PLGA, respectively. Moreover, experiments were designed to verify whether the fabricated electrospun substrates were biocompatible for ovine amniotic epithelial stem cells (oAECs) under in vitro conditions. Cell adhesion, survival, spatial organization on fibres, proliferation index, and DNA quantification after 48h culture, showed an enhanced adhesion and proliferation, especially for PLGA scaffolds. The favourable interaction between oAECs and the fibrous scaffolds was attributed to the greatly improved porosity and pore size distribution of the electrospun scaffolds. In addition, AECs can be considered ideal for tissue engineering especially when using biocompatible and opportunely produced scaffolds. PMID:27612719

  14. Research Progress in Poly(lactic acid ) /Layered Silicate Nanocomposites%聚乳酸/层状硅酸盐纳米复合材料研究进展

    Institute of Scientific and Technical Information of China (English)

    张玉霞; 刘学; 刘本刚; 王向东

    2012-01-01

    介绍了聚乳酸/层状硅酸盐纳米复合材料研究进展,阐述了其制备方法如原位聚合插层法、溶液插层法、熔融插层法等,详述了聚乳酸添加纳米层状硅酸盐后结构与性能的变化,包括复合材料的微观结构、结晶性能、热性能、力学性能、流变性能、加工性能、阻隔性能、阻燃性能的变化。研究表明,采用不同的制备方法如原位聚合插层法、溶液插层法、熔融插层法等能制得插层型、剥离型以及插层与剥离混合型聚乳酸/层状硅酸盐纳米复合材料;添加纳米层状硅酸盐后,得到的聚乳酸/层状硅酸盐纳米复合材料结晶速率提高,结晶度增加,说明层状硅酸盐起到了成核剂的作用;热稳定性、拉伸模量和冲击强度、阻透性能和阻燃性能都有不同程度提高;流变性能也得到改善。%Research advances in the preparation and properties of poiy (lactic acid ) /layered silicate nanocomposites were introduced. Details on preparation technologies of poly(lactic acid) /layered silicate nanocomposites such as intercalation from solution, in-situ intercalative polymerization, melt intercalation technique, and their properties such as morphologies, crystallization behavior, thermal performance, mechanical properties, rheological behavior, processing ability, barrier performance and flame retardance, etc. It was shown that poly(lactie acid)/layered silicate nanocomposites with interealative or/and exfoliated structure by the three preparation processes were made respectively. Their properties, including crystallization rate and degree, thermal stability, tensile modulus and impact strength, gas barrier and flame retardance, as well as rheological behavior were improved.

  15. Exploring the biodegradation and toxicity of naphthenic acids present in Athabasca oil sands process affected waters using simulated wetlands

    International Nuclear Information System (INIS)

    Naphthenic acids (NAs) are a persistent group of dissolved organic acids found in oil sands process affected water (OSPW) from the Athabasca Oil Sands (AOS) in northern Alberta. This study investigated the feasibility of reducing the toxicity of OSPW in wetland environments, and proposed a strategy for reclamation at the AOS. Laboratory microcosms were used to mimic natural wetlands. The purpose was to determine if the toxicities of OSPWs generated by Syncrude Canada Ltd. (Syncrude) and Suncor Energy Inc. (Suncor) change with time as a result of aging and biodegradation. Experiments involved 2 types of OSPW obtained from Syncrude and Suncor. Nutrient availability (nitrogen and phosphorus enrichment) was increased for both short and long hydraulic retention times (40 and 400 days). The NAs found in the OSPW were tracked over the course of one year using Fourier Transform Infrared Spectroscopy, Gas Chromatography/Mass Spectrometry and Microtox bioassays. The objective was to determine the relationships between total NA concentrations, the degree to which different sub-groups of NAs are biodegraded and any potential reduction in OSPW toxicity

  16. 卟啉四臂星型聚乳酸的制备与表征%PREPARATION AND CHARACTERIZATION OF FOUR ARMED STAR POLYLACTIC ACID WITH PORPHYRIN CORE

    Institute of Scientific and Technical Information of China (English)

    李建忠; 姜飞; 万晓波

    2012-01-01

    利用本体聚合方法,采用辛酸亚锡为催化剂,四氨基苯基卟啉为引发剂,引发丙交酯开环聚合,制备四臂星型聚乳酸功能高分子材料.采用1 H-NMR,FTIR,GPC等对星型聚合物的分子结构、分子量及其分布等进行了研究.利用溶液浇铸成膜方法,制备了聚乳酸薄膜材料;并利用XRD方法,研究了聚乳酸薄膜的结构.研究表明,利用四氨基苯基卟啉为引发剂,合成了以卟啉为核的四臂星型聚合物,其溶液浇铸薄膜具有正交晶系α晶型结构,而线型聚乳酸呈非晶态结构.利用紫外可见吸收光谱研究了星型聚乳酸的光谱性质,结果表明合成聚合物具有锡卟啉的光学特性.%Star poly (lactic acid) was successfully synthesized via bulk ring opening polymerization of lactide using meso-tetra(p-aminophenyl) porphyrin (TAPP)as initiator and stannous octanoate (Sn(Oct)2)as catalyst under vacuum. Molecular structure of the four armed poly ( lactic acid) was characterized via H-NMR and FTIR. It was confirmed that the star poly (lactic acid) was comprised with four-armed polymer chain and a tin porphyrin core. The molecular weight was also studied via GPC and H-NMR,and molecular weight distribution was also characterized (Mw/Mn =1.97). Both star poly (lactic acid) film and linear poly (lactic acid) film were prepared using solution-casting method. Structural analysis via X-ray diffraction indicates that the star poly (lactic acid) films display the orthorhombic α-crystalline form, while linear poly (lactic acid) films display amorphous structure. The photoelectron study of the functional poly (lactic acid) via UV-Vis absorption spectra reveals that the star poly (lactic acid) displays photoelectric property of tin porphyrin.

  17. Mechanical characterization of commercial biodegradable plastic films

    Science.gov (United States)

    Vanstrom, Joseph R.

    Polylactic acid (PLA) is a biodegradable plastic that is relatively new compared to other plastics in use throughout industry. The material is produced by the polymerization of lactic acid which is produced by the fermentation of starches derived from renewable feedstocks such as corn. Polylactic acid can be manufactured to fit a wide variety of applications. This study details the mechanical and morphological properties of selected commercially available PLA film products. Testing was conducted at Iowa State University and in conjunction with the United States Department of Agriculture (USDA) BioPreferred ProgramRTM. Results acquired by Iowa State were compared to a similar study performed by the Cortec Corporation in 2006. The PLA films tested at Iowa State were acquired in 2009 and 2010. In addition to these two studies at ISU, the films that were acquired in 2009 were aged for a year in a controlled environment and then re-tested to determine effects of time (ageing) on the mechanical properties. All films displayed anisotropic properties which were confirmed by inspection of the films with polarized light. The mechanical testing of the films followed American Society for Testing and Materials (ASTM) standards. Mechanical characteristics included: tensile strength (ASTM D882), elongation of material at failure (ASTM D882), impact resistance (ASTM D1922), and tear resistance (ASTM D4272). The observed values amongst all the films ranged as followed: tensile strength 33.65--8.54 MPa; elongation at failure 1,665.1%--47.2%; tear resistance 3.61--0.46 N; and puncture resistance 2.22--0.28 J. There were significant differences between the observed data for a number of films and the reported data published by the Cortec Corp. In addition, there were significant differences between the newly acquired material from 2009 and 2010, as well as the newly acquired materials in 2009 and the aged 2009 materials, suggesting that ageing and manufacturing date had an effect on

  18. Mechanical Property Characterization of Plasticized Sugar Beet Pulp and Poly(lactic acid) Green Composites using Acoustic Emission and Confocal Microscopy.

    Science.gov (United States)

    Sorbitol and glycerol were used to plasticize sugar beet pulp-poly (lactic acid) green composites. The plasticizer was incorporated into sugar beet pulp (SBP)at 0, 10, 20, 30 and 40% w/w at low temperature and shear and then compounded with PLA using twin-screw extrusion and injection molding. The...

  19. Anaerobic biodegradation of long chain fatty acids : biomethanisation of biomass-associated LCFA as a challenge for the anaerobic treatment of effluents with high lipid/LCFA content

    OpenAIRE

    Pereira, M.A.

    2003-01-01

    Tese de doutoramento em Engenharia Biológica e Química. This work was focused on the anaerobic biodegradation of Long Chain Fatty Acids, especially those that are associated to anaerobic sludge by mechanisms of adsorption, precipitation or entrapment. When continuously fed with oleic acid (EGSB reactors, influent concentrations between 2 and 8 g COD/l and HRT=1 day), suspended and granular anaerobic sludge accumulated palmitic acid. This LCFA was efficiently biomethanised in batch assays, ...

  20. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Tan, Huaping, E-mail: hptan@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Hu, Xiaohong [School of Material Engineering, Jinling Institute of Technology, Nanjing (China)

    2015-11-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion.

  1. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

    International Nuclear Information System (INIS)

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion

  2. Panorama setorial e perspectivas na área de polímeros biodegradáveis Biodegradable polymers: sectorial overview and prospects

    Directory of Open Access Journals (Sweden)

    Daniele M. B. Falcone

    2007-03-01

    Full Text Available Neste trabalho, envolvendo polímeros biodegradáveis, buscou-se obter indicadores por meio da análise de patentes para avaliar as perspectivas e oportunidades de atuação da área de polímeros. Utilizou-se para tal a base de dados Espacenet e o software Vantage Point. São matéria desse estudo os polímeros: poli(hidroxibutirato - PHB, poli(hidroxibutirato-co-hidroxivalerato - PHBV, poli(ácido lático - PLA, poli(épsilon-caprolactona - PCL e os polihidroxialcanoatos (PHAs, tratados mais detalhadamente por serem a classe geral dos poliésteres microbiais. Verificou-se que a área de polímeros biodegradáveis, apesar de recente e em desenvolvimento, apresenta grande potencial mediante o panorama atual de consumo dos materiais poliméricos. Observou-se, de uma forma geral, uma grande diversidade de temas e oportunidades de estudo em compostos, blendas, biodegradação e aplicações.This work on biodegradable polymers involved an analysis of patents to identify indicators for evaluating the prospects and opportunities of action in the field of polymers. We used the Spacenet database and Vantage Point software. The study encompassed the following polymers: polyhydroxybutyrate - PHB, polyhydroxybutyrate-co-hydroxyvalerate - PHBV, polylactic acid - PLA, poly (epsilon-caprolactone - PCL and the polyhydroxyalkanoates (PHAs, dealt in greater detail because they represent the general class of microbial polyesters. We found that, although the field of biodegradable polymers is new and still under development, it holds great potential in view of present widespread use of polymeric materials. Overall we found a great diversity of themes and opportunities for studies on compounds, blends, biodegradation and applications.

  3. Stability of biodegradable radioactive rhenium (Re-186 and Re-188) microspheres after neutron-activation

    International Nuclear Information System (INIS)

    Our objective was to determine if microspheres made from the biodegradable polymer poly(lactic acid) that contained rhenium could withstand the conditions of direct neutron activation necessary to produce therapeutic amounts of radioactive rhenium. The radiation damage of the polymer produced by γ-doses of up to 1.05 MGy from Re-186 and Re-188 was examined by scanning electron microscopy and size exclusion chromatography. At a thermal neutron flux of 1.5x1013 n/cm2/s the microspheres melted after 3 h in the nuclear reactor, but suffered little damage after 1 h of radiation and released less than 5% of the radioactivity during incubation in buffer at 37 deg. C. The radioactive microspheres produced in this manner have a specific activity too low for radioembolization for treatment of liver tumors, but could be injected directly into tumors or applied topically to the wound bed of partially resected tumors

  4. In vitro perforation of human epithelial carcinoma cell with antibody-conjugated biodegradable microspheres illuminated by a single 80 femtosecond near-infrared laser pulse

    Directory of Open Access Journals (Sweden)

    Terakawa M

    2012-05-01

    Full Text Available Mitsuhiro Terakawa, Yasuyuki Tsunoi, Tatsuki MitsuhashiDepartment of Electronics and Electrical Engineering, Keio University, Yokohama, Kanagawa, JapanAbstract: Pulsed laser interaction with small metallic and dielectric particles has been receiving attention as a method of drug delivery to many cells. However, most of the particles are attended by many risks, which are mainly dependent upon particle size. Unlike other widely used particles, biodegradable particles have advantages of being broken down and eliminated by innate metabolic processes. In this paper, the perforation of cell membrane by a focused spot with transparent biodegradable microspheres excited by a single 800 nm, 80 fs laser pulse is demonstrated. A polylactic acid (PLA sphere, a biodegradable polymer, was used. Fluorescein isothiocyanate (FITC-dextran and short interfering RNA were delivered into many human epithelial carcinoma cells (A431 cells by applying a single 80 fs laser pulse in the presence of antibody-conjugated PLA microspheres. The focused intensity was also simulated by the three-dimensional finite-difference time-domain method. Perforation by biodegradable spheres compared with other particles has the potential to be a much safer phototherapy and drug delivery method for patients. The present method can open a new avenue, which is considered an efficient adherent for the selective perforation of cells which express the specific antigen on the cell membrane.Keywords: femtosecond laser, drug delivery, transfection, biodegradable polymer

  5. SYNTHESIS AND CHARACTERIZATION OF STEREOBLOCK POLY(LACTIC ACID)S%聚乳酸立构嵌段共聚物的合成与表征

    Institute of Scientific and Technical Information of China (English)

    东为富; 殷宏军; 施冬健; 陈明清; 张珣

    2011-01-01

    Stereoblock poly (lactic acid) s were successfully synthesized by ring-opening polymerization of D-LA and L-LA.The chemical structure of polyester was characterized by using FTIR.Glass transition temperature and crystallization were measured by using DSC and XRD, which indicated that the poly (lactic acid) s exhibited the sterecomplex behaviors.The molecule weight measure by Ubbelohde viscometer was 25600.%以左旋和右旋丙交酯为原料,通过开环聚合制备了含有左旋和右旋乳酸链段的聚乳酸立构嵌段共聚物.采用红外光谱对其分子结构进行表征,表明共聚物已成功合成;并采用差示扫描量热仪和X射线衍射仪对共聚物的熔点和晶型进行研究,表明所得嵌段共聚物具有立构复合结构;采用乌氏粘度计对共聚物的分子量进行研究,表明共聚物的粘均分子量为25600.

  6. Síntese e caracterização do copolímero poli (ácido lático-b-glicol etilênico Synthesis and characterization of poly(lactic acid-b-ethylene glycol copolymer

    Directory of Open Access Journals (Sweden)

    Walker S. Drumond

    2004-06-01

    Full Text Available Duas séries de copolímeros triblocos, poli (ácido lático-b-etileno glicol (PLA-PEO-PLA, foram sintetizados a partir do éster cíclico l,l-lactideo, usando octoato de estanho como iniciador e poli (etileno glicol (PEG (Mn = 4000 ou 600, di-hidróxi terminado, como co-iniciador. A ligação química entre os segmentos PEG e PLA foi confirmada pelas técnicas de espectroscopia no infravermelho (FTIR e Ressonância Magnética Nuclear de Hidrogênio (RMN-¹H e análise térmica. O grau de polimerização do bloco PLA, DP PLA, no copolímero foi estimado por RMN-¹H e mostrou variação em função da massa molar do PEG e do aumento da concentração relativa de l,l lactídeo na mistura reacional. O aspecto dos copolímeros sintetizados variou de acordo com o tamanho dos blocos hidrofílico e hidrofóbico presentes em sua estrutura. Testes de solubilidade mostraram comportamento anfifílico para o produto sintetizado. Os segmentos de PLA formaram uma fase cristalina enquanto a fase cristalina correspondente aos segmentos PEG não foi observada.Two series of tri-block copolymers, poly(lactic acid-b-ethylene glycol (PLA-PEG-PLA, were synthesized from l,l-lactide using stannous di-octoate as initiator and di-hydroxy terminated poly(ethylene glycol (PEG (Mn= 600 or 4000 as co-initiator. The chemical linkage between the PEG segment and the PLA segments was confirmed by Fourier transform infrared spectroscopy (FTIR, by proton magnetic resonance spectroscopy (¹H-NMR and thermal analyses. The polymerization degree of PLA segments in copolymers, DP PLA, was estimated from ¹H-NMR spectra and has shown a dependence on the PEG molar mass and the relative l,l-lactide feed concentration. The physical aspect of copolymers changed according to the hydrophilic and hydrophobic segments lengths. The solubility tests revealed the amphiphilic nature of copolymers. Longer PLA segments in copolymers still presented crystallinity while the crystallization of the PEG

  7. Regeneration of Three-Way Automobile Catalysts using Biodegradable Metal Chelating Agent – S, S-Ethylenediamine Disuccinic Acid (S, S-EDDS)

    Science.gov (United States)

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S. Ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various c...

  8. Effects of radiation-induced crosslinking on thermal and mechanical properties of poly(lactic acid) composites reinforced by basalt fiber

    International Nuclear Information System (INIS)

    Poly (lactic acid)/ basalt fiber (PLA/BF) composites were prepared by melt blending with a cross-linking agent, triallyl isocyanurate (TAIC). The thermal and mechanical properties of the composites were investigated through gel fraction, heat defection temperature (HDT), tensile tests and scanning electron microscopy (SEM). Under certain conditions, the HDT of composites was dramatically increased to 140℃ after irradiation. Tensile properties were enhanced as well. Both these improvements were consistent with changes of the fracture morphology. Compatibilization and concomitant enhancement of the interfacial adhesive between the polymer matrix and the inorganic fiber were achieved as seen from SEM photos, as a result of the formation of co-crosslinking and grafting structures at the interface according to the determination of gelation extraction. (authors)

  9. Preparation of tissue engineering porous scaffold with poly(lactic acid) and polyethylene glycol solution blend by solvent-casting/particulate-leaching

    International Nuclear Information System (INIS)

    Polyethylene glycol/poly(lactic acid) solution blend is employed as the raw materials to prepare porous scaffold of potential usage in tissue engineering. The solution blend can be naturally introduced in the classical solvent casting/particular leaching technique in porous matrix preparation. The PEG presence is to modify the degradation behavior of scaffolds to fit particular requirements in tissue engineering. The porous matrix of PEG/PLA with various weight ratios are made with pores size ∼250 μm. The SEM characterizations have been done to investigate the porous morphology of products, the results indicate that though with the clear semi-miscibility feature of PEG/PLA blends, the macro-structure is not significantly affected by the PEG content percentage. The degradation results show an enhanced weight loss rate with the presence of PEG as expected. (paper)

  10. Sprayed microspheres of poly(lactic acid) obtained with calcium compounds; Microesferas aspergidas de poli(acido latico) obtidos com compostos de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Raquel P.; Picciani, Paulo H. de Souza; Dias, Marcos L., E-mail: raquelpires@ima.ufrj.br [Instituto de Macromoleculas - Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ (Brazil)

    2011-07-01

    In this work PLLA and PDLA were synthesized using calcium methoxide (Ca(OMe){sub 2}) as initiator. This compound shows good activity in the bulk polymerization of L-lactide (LLA) and D-lactide (DLA) producing polymers with average molecular weight up to 22,300 g/mol, but with microstructure containing a significant amount of estereoerros, as revealed by {sup 13} C NMR. Block copolymers containing blocks of L-and D-lactic acid were also prepared, using the method of sequential addition of LLA and DLA in an attempt to obtain stereo complexes. Analyses of scanning electron microscopy (SEM) revealed that the polymers obtained with catalysts of calcium produced PLA microspheres with diameters of around 5 {mu}m via electro spray technique. (author)

  11. Custom-made polyglycolic acid/polylactic acid scaffolds cocultured with bone marrow stroma cells of canine in vitro%定制型聚羟基乙酸/聚乳酸支架与犬骨髓基质细胞的体外复合培养

    Institute of Scientific and Technical Information of China (English)

    徐华; 韩冬; 董佳生; 沈国雄; 俞哲元; 柴岗; 艾松涛

    2011-01-01

    背景:聚羟基乙酸、聚乳酸均属于脂肪族聚酯,是一种具有一定机械强度和良好成型性能的生物可降解材料,在体内无毒,不聚积,且有良好的生物相容性.目的:应用CAD、CAM、快速成型和激光扫描技术等组成的数字医学系统制作聚羟基乙酸/聚乳酸三维仿真的下颌支髁突形态模型,并检测其细胞生物相容性.方法:通过CT扫描获得犬头颅骨影像信息,以CAD和CAM实现下颌骨髁突形态的三维重建影像,快速成型技术获得下颌骨髁突的树脂阳模.阴阳模转换获得相应石膏阴模,聚羟基乙酸/聚乳酸在阴模内成型.抽取犬髂骨骨髓获得骨髓基质细胞,与定制型聚羟基乙酸/聚乳酸支架在体外复合培养,检测支架材料的生物相容性.结果与结论:定制型聚羟基乙酸/聚乳酸支架和影像原型比较,当测试点误差小于1.0 mm时,复合率大于95%.通过CAD、CAM、快速成型技术、预压成型技术和激光扫描技术等组成的数字医学系统可实现颅颌面下颌骨髁突形态结构聚羟基乙酸/聚乳酸生物材料的三维仿真.体外复合培养结果表明,定制型聚羟基乙酸/聚乳酸支架和骨髓基质细胞具有良好的生物相容性.%BACKGROUND: Polyglycolic acid (PGA) and polylactic acid (PLA) are belonging to the aliphatic polyester, which is a certainmechanical strength and good shaping properties of biodegradable material, innocuity in vivo, without accumulation, and has agood biocompatibility.OBJECTIVE: To produce PGA/PLA three-dimensional simulation of the mandibular condylar shape model by using of CAD, CAM,rapid prototyping and laser scanning technology and other components of digital medical systems, and to detect its cellbiocompatibility.METHODS: Parietal bone image information of canine was obtained by CT scan, condyle of mandible morphologythree-dimensional reconstruction images were performed by CAD and CAM, resin male of condyle of mandible was obtained

  12. Enhancement of sludge anaerobic biodegradability by combined microwave-H2O2 pretreatment in acidic conditions.

    Science.gov (United States)

    Eswari, Parvathy; Kavitha, S; Kaliappan, S; Yeom, Ick-Tae; Banu, J Rajesh

    2016-07-01

    The aim of this study was to increase the sludge disintegration and reduce the cost of microwave (MW) pretreatment. Thermodynamic analysis of MW hydrolysis revealed the best fit with a first-order kinetic model at a specific energy of 18,600 kJ/kg total solids (TS). Combining H2O2 with MW resulted in a significant increment in solubilization from 30 to 50 % at 18,600 kJ/kg TS. The pH of H2O2-assisted MW-pretreated sludge (MW + H2O2) was in the alkaline range (pH 9-10), and it made the sludge unfavorable for subsequent anaerobic digestion and inhibits methane production. In order to nullify the alkaline effect caused by the MW + H2O2 combination, the addition of acid was considered for pH adjustment. H2O2-assisted MW-pretreated sludge in acidic conditions (MW + H2O2 + acid) showed a maximum methane production of 323 mL/g volatile solids (VS) than others during anaerobic biodegradability. A cost analysis of this study reveals that MW + H2O2 + acid was the most economical method with a net profit of 59.90 €/t of sludge. PMID:27026550

  13. Removal and biodegradation of naphthenic acids by biochar and attached environmental biofilms in the presence of co-contaminating metals.

    Science.gov (United States)

    Frankel, Mathew L; Bhuiyan, Tazul I; Veksha, Andrei; Demeter, Marc A; Layzell, David B; Helleur, Robert J; Hill, Josephine M; Turner, Raymond J

    2016-09-01

    This study evaluated the efficacy of using a combined biofilm-biochar approach to remove organic (naphthenic acids (NAs)) and inorganic (metals) contaminants from process water (OSPW) generated by Canada's oil sands mining operations. A microbial community sourced from an OSPW sample was cultured as biofilms on several carbonaceous materials. Two biochar samples, from softwood bark (SB) and Aspen wood (N3), facilitated the most microbial growth (measured by protein assays) and were used for NA removal studies performed with and without biofilms, and in the presence and absence of contaminating metals. Similar NA removal was seen in 6-day sterile N3 and SB assays (>30%), while biodegradation by SB-associated biofilms increased NA removal to 87% in the presence of metals. Metal sorption was also observed, with up to four times more immobilization of Fe, Al, and As on biofilm-associated biochar. These results suggest this combined approach may be a promising treatment for OSPW. PMID:27259191

  14. The Influence of Solid-State Drawing on Mechanical Properties and Hydrolytic Degradation of Melt-Spun Poly(Lactic Acid (PLA Tapes

    Directory of Open Access Journals (Sweden)

    Fang Mai

    2015-12-01

    Full Text Available The influence of solid-state drawing on the morphology of melt-spun poly(l-lactic acid (PLLA tapes, and the accompanying changes in mechanical and degradation behaviour have been studied. Mechanical properties are found to be strongly dependent on both applied draw ratio and drawing temperature. Moduli of these highly oriented tapes are significantly increased compared to as-extruded tapes at both ambient and elevated temperatures. Interestingly, drawing leads to a significant increase in elongation to break (~3 times and toughness (~13 times compared to as-extruded tapes. Structural and morphological characterization indicates strain-induced crystallization as well as an increase in orientation of the crystalline phase at small strains. Upon further stretching, an “overdrawing” regime is observed, with decreased crystalline orientation due to the breakage of existing crystals. For fixed draw ratios, a significant increase in Young’s modulus and tensile strength is observed with increasing drawing temperature, due to a higher crystallinity and orientation obtained for tapes drawn at higher temperatures. FT-IR results indicate no crystal transformation after drawing, with the α-form being observed in all tapes. Hydrolytic degradability of PLLA was significantly reduced by solid-state drawing.

  15. Biosynthesis of poly(g-L-glutamic acid) and comparative studies on the biodegradability of the g- and a-enantiomeric forms of the poly (glutamic acid) by Bacillus Licheniformis NCIMB 11709

    OpenAIRE

    Marqués Calvo, M. Soledad; Bou Serra, Jordi; Cerdà Cuéllar, Marta

    2013-01-01

    Poly (y-glutamic acid), a novel polyanionic and multifunctional macromolecule synthesized by Bacillus species, has attracted considerable attention because of its eco-friendly, biodegradable and biocompatible characteristics. Recently, its application in a wide range of fields such as food, agriculture, medicine, hygiene, cosmetics and the environment has been explored. This book discusses the chemistry, food sources and health benefits of glutamic acid.

  16. 端羟基聚乳酸低聚物的制备与性能研究%Preparation and Properties of Hydroxyl Terminated Polylactic Acid Oligomer

    Institute of Scientific and Technical Information of China (English)

    张苗苗; 常军; 杨超; 张恒; 许贺

    2015-01-01

    以左旋乳酸和1,4-丁二醇为原料,氯化亚锡(SnCl2・2H2O)和辛酸亚锡(Sn(OCT)2)为催化剂通过熔融缩聚法合成端羟基聚乳酸(HO-PLLA-OH)。熔融缩聚反应工艺条件为:0.1%SnCl2・2H2O(mol%)和0.1%Sn(OCt)2(mol%),聚合温度控制在180℃,反应时间为10 h,并采用红外光谱(IR)、核磁共振谱(1H-NMR),测得产物黏均分子量(Mη)为9528,差示扫描热分析( DSC)等手段对聚合物的热性能进行了研究。低聚物在缓冲液中20天失重率为43.1%。%L-lactic acid and 1,4-butanediol were used to synthesize hydroxyl terminated PLLA( HO-PLLA-OH) by melt polycondensation with stannous chloride and stannous octoate as catalyst.The polymerization conditions was attributed as follows:the dose of SnCl2・ 2H2 O and Sn(OCT)2 reached 0.1%, polymerization temperature was 180℃, polymerization time was 10 h.The synthesized HO-PLLA-OH was detected by infrared spectroscopy ( IR) and proton nuclear magnetic resonance (1H-NMR).The viscosity-average molecular weight was exceeded 9528 detected by ubbelohde viscometer, and the thermal perproty was investigated by differential scanning calorimeter(DSC).Weight loss of HO-PLLA-OH was 43.1%in 20 days.

  17. Adhesion of biocompatible and biodegradable micropatterned surfaces

    NARCIS (Netherlands)

    Kaiser, J.S.; Kamperman, M.M.G.; Souza, E.J.; Schick, B.; Arzt, E.

    2011-01-01

    We studied the effects of pillar dimensions and stiffness of biocompatible and biodegradable micropatterned surfaces on adhesion on different compliant substrates. The micropatterned adhesives were based on biocompatible polydimethylsiloxane (PDMS) and biodegradable poly(lactic-co-glycolic) acid (PL

  18. 骨髓间充质干细胞复合聚乳酸-羟基乙酸材料治疗大鼠神经损伤的实验研究%Bone Marrow Mesenchymal Stem Cells Combined with Polylactic Glycolic Acid Scaffold for Rat Neural Injury

    Institute of Scientific and Technical Information of China (English)

    符厚圣; 周兴; 桂有富; 郑煜; 潘建刚

    2011-01-01

    Objectives To study separately the effect of bone marrow mesenchymal stem cells (BMSCs) and differentiated neural - like cells combined with polylactic glycolic acid ( PLGA ) scaffolds, both composite which restore to SD rat nerve injury. Methods BMSCs were cultured by differential adherence,and composited PLGA,via scanning electron microscope to investigate the information of BMSCs'adhesion, proliferation and induction into neural - like cells in the scaffolds. Bold scaffold, BMSCs - PLGA complex, and neural - like cells - PLGA complex were separately transplanted into SD rat models, with the injury for right sciatic nerve, and obsvered SD rat models during 60 days after operation. Results BMSCs and neural - like cells can be exactly adhere to, proliferate and grow on the PLGA;BMSCs and neural -like cells combined with PLGA, which can restore to nerve injury. Conclusions BMSCs and differentiated neural - like cells combined with polylactic glycolic acid (PLGA) scaffolds,which can be used as a method of tissue engineering,to treat neurogenic bladder caused by spinal cord injury and advanced diabetes.%目的 研究骨髓间充质干细胞(Bone Marrow Mesenchymal Stem Cells,BMSCs)及其分化的神经样细胞分别与聚乳酸-羟基乙酸(polylactic glycolic acid,PLGA)支架材料复合修复大鼠神经损伤的效果.方法 将BMSCs复合PIGA培养,通过扫描电镜观察BMSCs在PLGA上的黏附、增殖并诱导分化成神经样细胞的情况;然后分别将单纯的PLGA、BMSCs-PLGA复合物以及神经样细胞-PLGA复合物分别移植入3组右侧坐骨神经损伤的SD大鼠模型中,术后观察三组动物60 d.结果 BMSCs及诱导分化生成的神经样细胞能在PLGA良好的黏附、增殖和生长;复合PLGA移植后能修复损伤的神经.结论 BMSCs及神经样细胞复合PLGA移植可作为组织工程治疗脊髓损伤及糖尿病晚期神经源性膀胱的一种方法.

  19. Effect of acid dopants in biodegradable gel polymer electrolyte and the performance in an electrochemical double layer capacitor

    Science.gov (United States)

    Sudhakar, Y. N.; Selvakumar, M.; Krishna Bhat, D.

    2015-09-01

    Proton-conducting biodegradable gellan gum gel polymer electrolytes (GPEs) have been prepared using three different dopants, namely ortho-phosphoric (o-H3PO4), sulfuric (H2SO4) and hydrochloric acids (HCl). The GPEs were cross-linked using borax. The polymeric gels were characterized by spectroscopic, thermal, ionic conductivities and dielectric measurements. Proton conductivity was in the range of 5.1 × 10-3 to 3.7 × 10-4 s cm-1 and activation energies were between 0.14 meV and 0.19 meV, at different temperatures. Among the doped acids, the H3PO4 doped GPE exhibited thermal stability at varying temperature. Electrochemical double layer capacitors (EDLCs) were fabricated using activated carbon as electrode material and GPEs. The EDLCs were tested using cyclic voltammetry, ac impedance spectroscopic and galvanostatic charge-discharge techniques. The maximum specific capacitance value was 146 F g-1 at a scan rate of 2 mV s-1. Quite stable values were obtained at a constant current density up to 1000 cycles.

  20. Biodegradable Photo-Crosslinked Thin Polymer Networks Based on Vegetable Oil Hydroxyfatty Acids

    Science.gov (United States)

    Novel crosslinked thin polymer networks based on vegetable oil hydroxyfatty acids (HFAs) were prepared by UV photopolymerization and their mechanical properties were evaluated. Two raw materials, castor oil and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) were used as sources of mono- and di-HFAs, r...

  1. G-SIMS of biodegradable homo-polyesters

    Science.gov (United States)

    Ogaki, R.; Green, F.; Li, S.; Vert, M.; Alexander, M. R.; Gilmore, I. S.; Davies, M. C.

    2006-07-01

    Static SIMS (SSIMS) is a powerful surface analytical technique which can provide detailed molecular information from organic surfaces. However, often much of the acquired information is too rich in detail and the data analysis relies on analysts' expertise and/or the limited number of materials in SSIMS libraries. Gilmore and Seah [Appl. Surf. Sci. 161 (2000) 465] recently developed a library independent technique, G-SIMS where extrapolation of the data to low surface plasma temperature reveals the un-degraded parent fragments from the SSIMS spectra. In this study, G-SIMS has been tested on biodegradable polyesters including: poly(glycolic acid) (PGA), poly(lactic acid) (PLA), poly(hydroxybutyrate) (PHB) and poly(caprolactone) (PCL). These materials are chosen to test G-SIMS capabilities on these structurally related compound series. The G-SIMS spectra derived from the SIMS spectra acquired from these polyesters yielded vital clues to fragmentation mechanisms as a function of molecular structure and highlight a powerful application of G-SIMS.

  2. Local sustained delivery of acetylsalicylic acid via hybrid stent with biodegradable nanofibers reduces adhesion of blood cells and promotes reendothelialization of the denuded artery

    Directory of Open Access Journals (Sweden)

    Lee CH

    2014-01-01

    Full Text Available Cheng-Hung Lee,1,2 Yu-Huang Lin,3 Shang-Hung Chang,1 Chun-Der Tai,3 Shih-Jung Liu,2 Yen Chu,4 Chao-Jan Wang,5 Ming-Yi Hsu,5 Hung Chang,6 Gwo-Jyh Chang,7 Kuo-Chun Hung,1 Ming-Jer Hsieh,1 Fen-Chiung Lin,1 I-Chang Hsieh,1 Ming-Shien Wen,1 Yenlin Huang81Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Linkou, 2Department of Mechanical Engineering, 3Graduate Institute of Medical Mechatronics, Chang Gung University, 4Laboratory of Cardiovascular Physiology, Division of Thoracic and Cardiovascular Surgery, 5Department of Medical Imaging and Intervention, 6Hematology-Oncology Division, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, 7Graduate Institute of Clinical Medicinal Sciences, Chang Gung University College of Medicine, Linkou, 8Department of Anatomical Pathology, Chang Gung Memorial Hospital, Linkou, Tao-Yuan, TaiwanAbstract: Incomplete endothelialization, blood cell adhesion to vascular stents, and inflammation of arteries can result in acute stent thromboses. The systemic administration of acetylsalicylic acid decreases endothelial dysfunction, potentially reducing thrombus, enhancing vasodilatation, and inhibiting the progression of atherosclerosis; but, this is weakened by upper gastrointestinal bleeding. This study proposes a hybrid stent with biodegradable nanofibers, for the local, sustained delivery of acetylsalicylic acid to injured artery walls. Biodegradable nanofibers are prepared by first dissolving poly(D,L-lactide-co-glycolide and acetylsalicylic acid in 1,1,1,3,3,3-hexafluoro-2-propanol. The solution is then electrospun into nanofibrous tubes, which are then mounted onto commercially available bare-metal stents. In vitro release rates of pharmaceuticals from nanofibers are characterized using an elution method, and a high-performance liquid chromatography assay. The experimental results suggest that biodegradable nanofibers

  3. Promoting endothelial recovery and reducing neointimal hyperplasia using sequential-like release of acetylsalicylic acid and paclitaxel-loaded biodegradable stents

    Directory of Open Access Journals (Sweden)

    Lee CH

    2014-08-01

    Full Text Available Cheng-Hung Lee,1,2 Chia-Ying Yu,2 Shang-Hung Chang,1 Kuo-Chun Hung,1 Shih-Jung Liu,2 Chao-Jan Wang,3 Ming-Yi Hsu,3 I-Chang Hsieh,1 Wei-Jan Chen,1 Yu-Shien Ko,1 Ming-Shien Wen1 1Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital-Linkou, Tao-Yuan, Taiwan; 2Department of Mechanical Engineering, Chang Gung University, Tao-Yuan, Taiwan; 3Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Tao-Yuan, Taiwan Introduction: This work reports on the development of a biodegradable dual-drug-eluting stent with sequential-like and sustainable drug-release of anti-platelet acetylsalicylic acid and anti-smooth muscle cell (SMC proliferative paclitaxel.Methods: To fabricate the biodegradable stents, poly-L-lactide strips are first cut from a solvent-casted film. They are rolled onto the surface of a metal pin to form spiral stents. The stents are then consecutively covered by acetylsalicylic acid and paclitaxel-loaded polylactide-polyglycolide nanofibers via electrospinning.Results: Biodegradable stents exhibit mechanical properties that are superior to those of metallic stents. Biodegradable stents sequentially release high concentrations of acetylsalicylic acid and paclitaxel for more than 30 and 60 days, respectively. In vitro, the eluted drugs promote endothelial cell numbers on days 3 and 7, and reduce the proliferation of SMCs in weeks 2, 4, and 8. The stents markedly inhibit the adhesion of platelets on days 3, 7, and 14 relative to a non-drug-eluting stent. In vivo, the implanted stent is intact, and no stent thrombosis is observed in the stent-implanted vessels without the administration of daily oral acetylsalicylic acid. Promotion of endothelial recovery and inhibition of neointimal hyperplasia are also observed on the stented vessels.Conclusion: The work demonstrates the efficiency and safety of the biodegradable dual-drug-eluting stents with sequential and sustainable drug release

  4. Biodegradable Polymers

    OpenAIRE

    Isabelle Vroman; Lan Tighzert

    2013-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  5. Controlled-release fertilizer prepared using a biodegradable aliphatic copolyester of poly(butylene succinate) and dimerized fatty acid.

    Science.gov (United States)

    Lubkowski, Krzysztof; Smorowska, Aleksandra; Grzmil, Barbara; Kozłowska, Agnieszka

    2015-03-18

    The preparation and characterization of a controlled-release multicomponent (NPK) fertilizer with the coating layer consisting of a biodegradable copolymer of poly(butylene succinate) and a butylene ester of dilinoleic acid (PBS/DLA) is reported. The morphology and structure of the resulting polymer-coated materials and the thickness of the covering layers were examined using X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray analysis. The mechanical properties of these materials were determined with a strength-testing machine. Nutrient release was measured in water using spectrophotometry, potentiometry, and conductivity methods. The results of the nutrient release experiments from these polymer-coated materials were compared with the requirements for controlled-release fertilizers. A conceptual model is presented describing the mechanism of nutrient release from the materials prepared in this study. This model is based on the concentrations of mineral components inside the water-penetrated fertilizer granules, the diffusion properties of the nutrients in water, and a diffusion coefficient through the polymer layer. The experimental kinetic data on nutrient release were interpreted using the sigmoidal model equation developed in this study. PMID:25715823

  6. CLAY CATALYZED SYNTHESIS OF BIO-DEGRADABLE POLY(GLYCOLIC ACID)

    Institute of Scientific and Technical Information of China (English)

    K. Durai Murugan; S. Radhika; I. Baskaran; R. Anbarasan

    2008-01-01

    Glycolic acid was polymerized under vacuum in the presence and absence of nano sized clay. The added clay catalyzed the condensation polymerization which can be confirmed by recording FT1R spectroscopy and intrinsic viscosity (Ⅳ) values. The relative intensity of C =O/CH is increased while increasing the amount of clay. DSC showed the appearance of multiple endotherms of poly(glycolic acid). TGA showed the percentage weight residue remain above 750℃ for polymer-nano composite system was 21% and hence proved the flame retardancy (char forming) nature. TEM confirmed the nano size of the clay used to catalyze the condensation reaction. The intrinsic viscosity value was increased with the increase of percentage weight of Hectorite type clay.

  7. Improved Biocompatibility of Novel Biodegradable Scaffold Composed of Poly-L-lactic Acid and Amorphous Calcium Phosphate Nanoparticles in Porcine Coronary Artery

    Directory of Open Access Journals (Sweden)

    Dongsheng Gu

    2016-01-01

    Full Text Available Using poly-L-lactic acid for implantable biodegradable scaffold has potential biocompatibility issue due to its acidic degradation byproducts. We have previously reported that the addition of amorphous calcium phosphate improved poly-L-lactic acid coating biocompatibility. In the present study, poly-L-lactic acid and poly-L-lactic acid/amorphous calcium phosphate scaffolds were implanted in pig coronary arteries for 28 days. At the follow-up angiographic evaluation, no case of stent thrombosis was observed, and the arteries that were stented with the copolymer scaffold had significantly less inflammation and nuclear factor-κB expression and a greater degree of reendothelialization. The serum levels of vascular endothelial growth factor and nitric oxide, as well the expression of endothelial nitric oxide synthase and platelet-endothelial cell adhesion molecule-1, were also significantly higher. In conclusion, the addition of amorphous calcium phosphate to biodegradable poly-L-lactic acid scaffold minimizes the inflammatory response, promotes the growth of endothelial cells, and accelerates the reendothelialization of the stented coronary arteries.

  8. Biodegradable polymers from organic acids by using activated sludge enriched by aerobic periodic feeding.

    Science.gov (United States)

    Dionisi, Davide; Majone, Mauro; Papa, Viviana; Beccari, Mario

    2004-03-20

    This article describes a new process for the production of biopolymers (polyhydroxyalkanoates, PHAs) based on the aerobic enrichment of activated sludge to obtain mixed cultures able to store PHAs at high rates and yields. Enrichment was obtained through the selective pressure established by feeding the carbon source in a periodic mode (feast and famine regime) in a sequencing batch reactor. A concentrated mixture of acetic, lactic, and propionic acids (overall concentration of 8.5 gCOD L(-1)) was fed every 2 h at 1 day(-1) overall dilution rate. Even at such high organic load (8.5 gCOD L(-1) day(-1)), the selective pressure due to periodic feeding was effective in obtaining a biomass with a storage ability much higher than activated sludges. The immediate biomass response to substrate excess (as determined thorough short-term batch tests) was characterized by a storage rate and yield of 649 mgPHA (as COD) g biomass (as COD)(-1) h(-1) and 0.45 mgPHA (as COD) mg removed substrates (as COD(-1)), respectively. When the substrate excess was present for more than 2 h (long-term batch tests), the storage rate and yield decreased, whereas growth rate and yield significantly increased due to biomass adaptation. A maximum polymer fraction in the biomass was therefore obtained at about 50% (on COD basis). As for the PHA composition, the copolymer poly(beta-hydroxybutyrate/beta-hydroxyvalerate) with 31% of hydroxyvalerate monomer was produced from the substrate mixture. Comparison of the tests with individual and mixed substrates seemed to indicate that, on removing the substrate mixture for copolymer production, propionic acid was fully utilized to produce propionylCoA, whereas the acetylCoA was fully provided by acetic and lactic acid. PMID:14966798

  9. Biodegradation of 2,4,5-trichlorophenoxyacetic acid by a pure culture of Pseudomonas cepacia.

    OpenAIRE

    Kilbane, J J; Chatterjee, D K; Karns, J S; Kellogg, S T; Chakrabarty, A M

    1982-01-01

    A pure culture of Pseudomonas cepacia, designated AC1100, that can utilize 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as its sole source of carbon and energy was isolated. An actively growing culture of AC1100 was able to degrade more than 97% of 2,4,5-T, present at 1 mg/ml, within 6 days as determined by chloride release, gas chromatographic, and spectrophotometric analyses. The ability of AC1100 to oxidize a variety of chlorophenols and related compounds is also reported.

  10. Characterization of biodegradable film based on zein and oleic acid added with nanocarbonate

    Directory of Open Access Journals (Sweden)

    Wanessa Ximenes Ribeiro

    2015-10-01

    Full Text Available Zein oleic acid films added with 1, 2 and 3 % (w/w of nanocarbonate and 30 % glycerol as plasticizer, were produced and evaluated according to their structure and functional properties. Structural characteristics were analyzed by optical and scanning electron microscopy (SEM. Water solubility and mechanical properties were determined according to ASTM methods. The increase of nanocarbonate concentration increased water solubility and influenced the color and mechanical properties. Optical and SEM of film samples added with nanocarbonate, shown low amount of pores and great fat globules size.

  11. Preparation of ultrafine poly(methyl methacrylate-co-methacrylic acid) biodegradable nanoparticles loaded with ibuprofen.

    Science.gov (United States)

    Saade, Hened; Diaz de León-Gómez, Ramón; Enríquez-Medrano, Francisco Javier; López, Raúl Guillermo

    2016-08-01

    Ibuprofen-loaded polymeric particles with around 9.2 nm in mean diameter, as determined by electron microscopy, dispersed in an aqueous media containing up to 12.8% solids were prepared by semicontinuous heterophase polymerization. The polymeric material is a (2/1 mol/mol) methyl methacrylate-co-methacrylic acid copolymer similar to Eudragit S100, deemed safe for human consumption and used in the manufacturing of drug-loaded pills as well as micro- and nanoparticles. The loading efficiency was 100%, attaining around 10-12% in drug content. Release studies showed that the drug is released from the nanoparticles at a slower rate than that in the case of free IB. Given their size as well as the pH values required for their dissolution, it is believed that this type of particles could be used as a basis for preparing nanosystems loaded with a variety of drugs. PMID:27126476

  12. Hyaluronic acid biodegradable material for reconstruction of vascular wall: a preliminary study in rats.

    Science.gov (United States)

    Pandis, Laura; Zavan, Barbara; Bassetto, Franco; Ferroni, Letizia; Iacobellis, Laura; Abatangelo, Giovanni; Lepidi, Sandro; Cortivo, Roberta; Vindigni, Vincenzo

    2011-02-01

    The objective of this preliminary study was to develop a reabsorbable vascular patch that did not require in vitro cell or biochemical preconditioning for vascular wall repair. Patches were composed only of hyaluronic acid (HA). Twenty male Wistar rats weighing 250-350 g were used. The abdominal aorta was exposed and isolated. A rectangular breach (1 mm × 5 mm) was made on vessel wall and arterial defect was repaired with HA made patch. Performance was assessed at 1, 2, 4, 8, and 16 weeks after surgery by histology and immunohistochemistry. Extracellular matrix components were evaluated by molecular biological methods. After 16 weeks, the biomaterial was almost completely degraded and replaced by a neoartery wall composed of endothelial cells, smooth muscle cells, collagen, and elastin fibers organized in layers. In conclusion, HA patches provide a provisional three-dimensional support to interact with cells for the control of their function, guiding the spatially and temporally multicellular processes of artery regeneration. PMID:21268111

  13. Aligned flax fibre/polylactate composites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Thygesen, Anders;

    2008-01-01

    The potential of biocomposites in engineering applications is demonstrated by using aligned flax fibre/polylactate composites as a materials model system. The failure stress of flax fibres is measured by tensile testing of single fibres and fibre bundles. For both fibre configurations, it is foun...... flax fibre composites and traditional fibre composites (exemplified by glass fibre composites) are presented. The stiffness per volume, per weight and per cost is compared for these two types of composites.......The potential of biocomposites in engineering applications is demonstrated by using aligned flax fibre/polylactate composites as a materials model system. The failure stress of flax fibres is measured by tensile testing of single fibres and fibre bundles. For both fibre configurations, it is found...... that failure stress is decreased by increasing the tested fibre volume. Based on two types of flax fibre preforms: carded sliver and unidirectional non-crimp fabric, aligned flax fibre/polylactate composites were fabricated with variable fibre content. The volumetric composition and tensile properties...

  14. Conformational Heat Capacity of Liquid Biodegradable Polymers in the Absence and Presence Water

    Science.gov (United States)

    Pyda, Marek; Nowak-Pyda, Elzbieta

    2007-03-01

    The conformational heat capacity of biodegradable polymers such as amorphous poly(lactic acid) PLA and starch with and without water have been evaluated from a fit of experimental data to a one-dimensional Ising-like model for two discrete states, characterized by parameters linked to stiffness, cooperativity, and degeneracy. For the starch-water system the additional changes in the conformational heat capacity arise from the interaction of the carbohydrate chains with water. The liquid heat capacities at constant pressure Cp, of amorphous PLA and partially liquid state of starch, starch-water have been computed as the sum of vibrational, external, and conformational contributions. The vibrational contribution was calculated as the heat capacity arising from group and skeletal vibrations. The external contribution was estimated from experimental data of the thermal expansivity and compressibility in the liquid state. The experimental liquid Cp agrees with these calculations to better than ±3%. The calculated liquid Cp with the solid Cp was employed in the quantitative thermal analysis of the experimental Cp of biodegradable polymer PLA, starch, and starch-water. Supported by European Union, grant (MIRG-CT-2006-036558), Cargill Dow LLC

  15. Fe3O4-As2O3-PLA复合体联合热疗对骨肉瘤治疗的细胞学研究%The study of magnetic nanoparticle containing arsenolite and polylactic acid in treatment of osteogenic sarcoma in combination with magnetic fluid hyperthemia in vitro

    Institute of Scientific and Technical Information of China (English)

    宋凯镔; 王文波

    2012-01-01

    目的 研究磁性三氧化砷-聚乳酸纳米粒子(Fe3O4-As2O3-PLA)复合体联合磁流体热疗对骨肉瘤细胞株UMR-106的生长的影响.方法 磁性三氧化砷-聚乳酸纳米粒子复合体的制备,透射电镜及荧光光度计对其形态及载药量进行观察,高频交变磁场中对其进行体外升温实验,骨肉瘤细胞的培养,四甲基偶氮唑蓝(MTT)比色法检测磁性三氧化砷-聚乳酸纳米粒子复合体联合磁流体热疗对骨肉瘤细胞株UMR-106生长的影响,流式细胞仪(FCM)检测凋亡细胞.结果 所制备的磁性三氧化砷-聚乳酸纳米粒子复合体比较均匀,粒径在60~70nm,载药量约为10.3%,在输出电流Ⅰ=300A的高频交变磁场中具有升温能力,且能达到肿瘤治疗的有效温度(41℃~46℃),磁性三氧化砷-聚乳酸纳米粒子复合体联合磁性热疗能抑制骨肉瘤细胞株UMR-106的生长,促进其调亡,且较单纯的As2O3液组及单纯的Fe3O4磁性纳米粒子热疗组的治疗效果明显.结论 Fe3O4-As2O3-PLA复合体联合磁性热疗可同时发挥As2O3的细胞毒性作用和磁感应加热的联合定向治疗作用,效果优于单纯的As2O3液组及单纯的Fe3O4磁性纳米粒子热疗组,为临床治疗骨肉瘤提供新的治疗方法.%Objective To observe the effect of magnetic nanoparticle containing arsenolite and polylactic acid in treatment of osteogenic sareoma( OS )cell line UMR - 106. Methods The magnetic nanoparticle con taining arsenolite and polylactic acid were prepared, and transmission electron microscope( TEM )and fluoropho tometer techniques were used to characterize its morphous and carrying dosage, mid the heat effect on magnetic nanopartielc was studied under altering magnetic field in vitro. Then, the UMR - 106 ceils were cultivated, and MTT assay was performed to examine the effect of magnetic nanopartielc containing arscnolitc and polylactic acid on the proliferation of UMR - 106 cells. By FCM.thc Percentage of apoptotic

  16. Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities.

    Directory of Open Access Journals (Sweden)

    Simon P Rout

    Full Text Available One design concept for the long-term management of the UK's intermediate level radioactive wastes (ILW is disposal to a cementitious geological disposal facility (GDF. Under the alkaline (10.013.0 anoxic conditions expected within a GDF, cellulosic wastes will undergo chemical hydrolysis. The resulting cellulose degradation products (CDP are dominated by α- and β-isosaccharinic acids (ISA, which present an organic carbon source that may enable subsequent microbial colonisation of a GDF. Microcosms established from neutral, near-surface sediments demonstrated complete ISA degradation under methanogenic conditions up to pH 10.0. Degradation decreased as pH increased, with β-ISA fermentation more heavily influenced than α-ISA. This reduction in degradation rate was accompanied by a shift in microbial population away from organisms related to Clostridium sporosphaeroides to a more diverse Clostridial community. The increase in pH to 10.0 saw an increase in detection of Alcaligenes aquatilis and a dominance of hydrogenotrophic methanogens within the Archaeal population. Methane was generated up to pH 10.0 with acetate accumulation at higher pH values reflecting a reduced detection of acetoclastic methanogens. An increase in pH to 11.0 resulted in the accumulation of ISA, the absence of methanogenesis and the loss of biomass from the system. This study is the first to demonstrate methanogenesis from ISA by near surface microbial communities not previously exposed to these compounds up to and including pH 10.0.

  17. Bone Marrow Mesenchymal Stem Cells Combined with Polylactic Glycolic Acid Scaffold for Rat Treating Bladder Function after Spinal Cord Injury%骨髓间充质干细胞复合聚乳酸-羟基乙酸支架材料移植修复大鼠脊髓损伤后膀胱功能的实验研究

    Institute of Scientific and Technical Information of China (English)

    桂有富; 周兴; 符厚圣; 潘建刚

    2011-01-01

    Objectives To study separately the effect of bone marrow mesenchymal stem cells(BMSCs)and differentiated neural-like cells combined with polylactic glycolic acid(PLGA)scaffolds,both composite which restore to SD rat,s bladder function after spinal cord injury.Methods Bold scaffold,BMSCs-PLGA complex,and neural-like cells-PLGA complex were separately transplanted into SD rat models with the transection for right spinal cord,the control group which is a direct suture half crosscut spinal cord group.And obsvered SD rat models during 60 days after operation.Results BMSCs and neural-like cells can be exactly adhere to,proliferate and grow on the PLGA;BMSCs and neural-like cells combined with PLGA,which can restore to spinal cord and promote the recovery of bladder function of SD rat models.Conclusions BMSCs and differentiated neural-like cells combined with PLGA scaffolds,which can be used as a method of tissue engineering,to treat bladder function caused by spinal cord injury.%目的 研究骨髓间充质干细胞(Bone Marrow Mesenchymal Stem Cells,BMSCs)及其分化生成的神经样细胞分别复合聚乳酸-羟基乙酸(Polylactic Glycolic Acid,PLGA)支架材料移植治疗大鼠脊髓损伤的效果.方法 分别将单纯的PLGA、BMSCs-PLGA复合物以及神经样细胞-PLGA复合物移植入3组半横切的SD大鼠脊髓损伤模型中,对照组为直接缝合脊髓组.术后观察4组动物60d.结果 BMSCs及其分化生成的神经样细胞能在PLGA上良好的黏附、增殖和生长,两者复合移植后能促进脊髓及膀胱排尿功能的恢复.结论 BMSCs及神经样细胞复合PLGA移植可作为组织工程治疗脊髓损伤后膀胱功能的一种方法.

  18. Affinity purification and characterization of a biodegradable plastic-degrading enzyme from a yeast isolated from the larval midgut of a stag beetle, Aegus laevicollis.

    Science.gov (United States)

    Suzuki, Ken; Sakamoto, Hironori; Shinozaki, Yukiko; Tabata, Jun; Watanabe, Takashi; Mochizuki, Atsushi; Koitabashi, Motoo; Fujii, Takeshi; Tsushima, Seiya; Kitamoto, Hiroko K

    2013-09-01

    Two yeast strains, which have the ability to degrade biodegradable plastic films, were isolated from the larval midgut of a stag beetle, Aegus laevicollis. Both of them are most closely related to Cryptococcus magnus and could degrade biodegradable plastic (BP) films made of poly(butylene succinate) (PBS) and poly(butylene succinate-co-adipate) (PBSA) effectively. A BP-degrading enzyme was purified from the culture broth of one of the isolated strains employing a newly developed affinity purification method based on the binding action of the enzyme to the substrate (emulsified PBSA) and its subsequent degradative action toward the substrate. Partial amino acid sequences of this enzyme suggested that it belongs to the cutinase family, and thus, the enzyme was named CmCut1. It has a molecular mass of 21 kDa and a degradative activity for emulsified PBSA which was significantly enhanced by the simultaneous presence of Ca(2+) or Mg(2+) at a concentration of about 2.5 mM. Its optimal pH was 7.5, and the optimal temperature was 40 °C. It showed a broad substrate specificity for p-nitrophenyl (pNP)-fatty acid esters ranging from pNP-acetate (C2) to pNP-stearate (C18) and films of PBSA, PBS, poly(ε-caprolactone), and poly(lactic acid). PMID:23224497

  19. Effect of single flame retardant aluminum tri-hydroxide and boric acid against inflammability and biodegradability of recycled PP/KF composites

    Science.gov (United States)

    Suharty, Neng Sri; Dihardjo, Kuncoro; Handayani, Desi Suci; Firdaus, Maulidan

    2016-03-01

    Composites rPP/DVB/AA/KF had been reactively synthesized in melt using starting material: recycled polypropylene (rPP), kenaf fiber (KF), multifunctional compound acrylic acid (AA), compatibilizer divinyl benzene (DVB). To improve the inflammability of composites, single flame retardant aluminum tri-hydroxide (ATH) and boric acid (BA) as an additive was added. The inflammability of the composites was tested according to ASTM D635. By using 20% ATH and 5% BA additive in the composites it is effectively inhibiting its time to ignition (TTI). Its burning rate (BR) can be reduced and its heat realease (%HR) decreases. The biodegradability of composites was quantified by its losing weight (LW) of composites after buried for 4 months in the media with rich cellulolytic bacteria. The result shows that the LW of composites in the presence 20% ATH and 5% BA is 6.3%.

  20. 聚氯乙烯接枝聚乳酸的合成及生物降解性%STUDIES ON SYNTHESIS AND BIODEGRADATION OF POLY(VINYL CHLORIDE) GRAFT POLY(LACTIC ACID)

    Institute of Scientific and Technical Information of China (English)

    郑敦胜; 郭锡坤; 吴伟升

    2006-01-01

    以环己酮为溶剂,将聚氯乙烯(PVC)与聚乳酸(PLA)的钠盐进行反应,合成了以PVC为主链、PLA为支链的接枝聚合物(PVC-g-PLA).讨论了实验条件对产物接枝率的影响,用核磁共振氢谱(1H-NMR)、红外光谱(FT-IR)和凝肢渗透色谱(GPC)对接枝聚合物进行了表征.采用土壤掩埋试验和扫描电镜(SEM)分析的方法,研究了接枝物的生物降解性.

  1. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  2. Synthesis and 3D printing of biodegradable polyurethane elastomer by a water-based process for cartilage tissue engineering applications.

    Science.gov (United States)

    Hung, Kun-Che; Tseng, Ching-Shiow; Hsu, Shan-Hui

    2014-10-01

    Biodegradable materials that can undergo degradation in vivo are commonly employed to manufacture tissue engineering scaffolds, by techniques including the customized 3D printing. Traditional 3D printing methods involve the use of heat, toxic organic solvents, or toxic photoinitiators for fabrication of synthetic scaffolds. So far, there is no investigation on water-based 3D printing for synthetic materials. In this study, the water dispersion of elastic and biodegradable polyurethane (PU) nanoparticles is synthesized, which is further employed to fabricate scaffolds by 3D printing using polyethylene oxide (PEO) as a viscosity enhancer. The surface morphology, degradation rate, and mechanical properties of the water-based 3D-printed PU scaffolds are evaluated and compared with those of polylactic-co-glycolic acid (PLGA) scaffolds made from the solution in organic solvent. These scaffolds are seeded with chondrocytes for evaluation of their potential as cartilage scaffolds. Chondrocytes in 3D-printed PU scaffolds have excellent seeding efficiency, proliferation, and matrix production. Since PU is a category of versatile materials, the aqueous 3D printing process developed in this study is a platform technology that can be used to fabricate devices for biomedical applications. PMID:24729580

  3. Effects of conventional and biodegradable microplastics on a marine ecosystem engineer (Arenicola marina) and sediment nutrient cycling.

    Science.gov (United States)

    Green, Dannielle Senga; Boots, Bas; Sigwart, Julia; Jiang, Shan; Rocha, Carlos

    2016-01-01

    Effects of microplastic pollution on benthic organisms and ecosystem services provided by sedimentary habitats are largely unknown. An outdoor mesocosm experiment was done to realistically assess the effects of three different types of microplastic pollution (one biodegradable type; polylactic acid and two conventional types; polyethylene and polyvinylchloride) at increasing concentrations (0.02, 0.2 and 2% of wet sediment weight) on the health and biological activity of lugworms, Arenicola marina (Linnaeus, 1758), and on nitrogen cycling and primary productivity of the sediment they inhabit. After 31 days, A. marina produced less casts in sediments containing microplastics. Metabolic rates of A. marina increased, while microalgal biomass decreased at high concentrations, compared to sediments with low concentrations or without microplastics. Responses were strongest to polyvinylchloride, emphasising that different materials may have differential effects. Each material needs to be carefully evaluated in order to assess their risks as microplastic pollution. Overall, both conventional and biodegradable microplastics in sandy sediments can affect the health and behaviour of lugworms and directly or indirectly reduce primary productivity of these habitats. PMID:26552519

  4. Are Biodegradable Osteosyntheses Still an Option for Midface Trauma? Longitudinal Evaluation of Three Different PLA-Based Materials.

    Science.gov (United States)

    Kolk, Andreas; Köhnke, Robert; Saely, Christoph H; Ploder, Oliver

    2015-01-01

    The aim was to evaluate three different biodegradable polylactic acid- (PLA-) based osteosynthesis materials (OM). These OM (BioSorb, LactoSorb, and Delta) were used in 64 patients of whom 55 (85.9%) had fractures of the zygoma, five (7.8%) in the LeFort II level, two of the frontal bone (3.1%), and two of the maxillary sinus wall (3.1%). In addition to routine follow-up (FU) at 3, 6, and 12 months (m) (T1, T2, and T3) all patients were finally evaluated at a mean FU after 14.1 m for minor (e.g., nerve disturbances, swelling, and pain) and major (e.g., infections and occlusal disturbances) complications. Out of all 64 patients 38 presented with complications; of these 28 were minor (43.8%) and 10 major (15.6%) resulting in an overall rate of 59.4%. Differences in minor complications regarding sensibility disturbance at T1 and T3 were statistically significant (P = 0.04). Differences between the OM were not statistically significant. Apart from sufficient mechanical stability for clinical use of all tested OM complications mostly involved pain and swelling probably mainly related to the initial bulk reaction attributable to the drop of pH value during the degradation process. This paper includes a review of the current aspects of biodegradable OM. PMID:26491680

  5. Are Biodegradable Osteosyntheses Still an Option for Midface Trauma? Longitudinal Evaluation of Three Different PLA-Based Materials

    Directory of Open Access Journals (Sweden)

    Andreas Kolk

    2015-01-01

    Full Text Available The aim was to evaluate three different biodegradable polylactic acid- (PLA- based osteosynthesis materials (OM. These OM (BioSorb, LactoSorb, and Delta were used in 64 patients of whom 55 (85.9% had fractures of the zygoma, five (7.8% in the LeFort II level, two of the frontal bone (3.1%, and two of the maxillary sinus wall (3.1%. In addition to routine follow-up (FU at 3, 6, and 12 months (m (T1, T2, and T3 all patients were finally evaluated at a mean FU after 14.1 m for minor (e.g., nerve disturbances, swelling, and pain and major (e.g., infections and occlusal disturbances complications. Out of all 64 patients 38 presented with complications; of these 28 were minor (43.8% and 10 major (15.6% resulting in an overall rate of 59.4%. Differences in minor complications regarding sensibility disturbance at T1 and T3 were statistically significant (P=0.04. Differences between the OM were not statistically significant. Apart from sufficient mechanical stability for clinical use of all tested OM complications mostly involved pain and swelling probably mainly related to the initial bulk reaction attributable to the drop of pH value during the degradation process. This paper includes a review of the current aspects of biodegradable OM.

  6. Are Biodegradable Osteosyntheses Still an Option for Midface Trauma? Longitudinal Evaluation of Three Different PLA-Based Materials

    Science.gov (United States)

    Kolk, Andreas; Köhnke, Robert; Saely, Christoph H.; Ploder, Oliver

    2015-01-01

    The aim was to evaluate three different biodegradable polylactic acid- (PLA-) based osteosynthesis materials (OM). These OM (BioSorb, LactoSorb, and Delta) were used in 64 patients of whom 55 (85.9%) had fractures of the zygoma, five (7.8%) in the LeFort II level, two of the frontal bone (3.1%), and two of the maxillary sinus wall (3.1%). In addition to routine follow-up (FU) at 3, 6, and 12 months (m) (T1, T2, and T3) all patients were finally evaluated at a mean FU after 14.1 m for minor (e.g., nerve disturbances, swelling, and pain) and major (e.g., infections and occlusal disturbances) complications. Out of all 64 patients 38 presented with complications; of these 28 were minor (43.8%) and 10 major (15.6%) resulting in an overall rate of 59.4%. Differences in minor complications regarding sensibility disturbance at T1 and T3 were statistically significant (P = 0.04). Differences between the OM were not statistically significant. Apart from sufficient mechanical stability for clinical use of all tested OM complications mostly involved pain and swelling probably mainly related to the initial bulk reaction attributable to the drop of pH value during the degradation process. This paper includes a review of the current aspects of biodegradable OM. PMID:26491680

  7. Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

    Science.gov (United States)

    Cardoso, Elisabeth C. L.; Scagliusi, Sandra R.; Lima, Luis F. C. P.; Bueno, Nelson R.; Brant, Antonio J. C.; Parra, Duclerc F.; Lugão, Ademar B.

    2014-01-01

    Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT).

  8. Enzyme-mediated bacterial biodegradation of an azo dye (C.I. Acid blue 113): reuse of treated dye wastewater in post-tanning operations.

    Science.gov (United States)

    Senthilvelan, T; Kanagaraj, J; Panda, R C

    2014-11-01

    "Dyeing" is a common practice used to color the hides during the post-tanning operations in leather processing generating plenty of wastewater. The waste stream containing dye as pollutant is severely harmful to living beings. An azo dye (C.I. Acid Blue 113) has been biodegraded effectively by bacterial culture mediated with azoreductase enzyme to reduce the pollution load in the present investigation. The maximum rate of dye degradation was found to be 96 ± 4 and 92 ± 4 % for the initial concentrations of 100 and 200 mg/l, respectively. The enzyme activity was measured using NADH as a substrate. Fourier transform infrared spectroscopy (FT-IR) analysis was confirmed that the transformation of azo linkage could be transformed into N2 or NH3 or incorporated into complete biomass. Breaking down of dye molecules to various metabolites (such as aniline, naphthalene-1,4-diamine, 3-aminobenzenesulfonic acid, naphthalene-1-sulfonic acid, 8-aminonaphthalene-1-sulfonic acid, 5,8-diaminonaphthalene-1-sulfonic acid) was confirmed by gas chromatography and mass spectra (GC-MS) and mass (electrospray ionization (ESI)) spectra analysis. The treated wastewater could be reused for dyeing operation in the leather processing, and the properties of produced leather were evaluated by conventional methods that revealed to have improved dye penetration into the grain layer of experimental leather sample and resulted in high levelness of dyeing, which helps to obtain the desired smoothness and soft leather properties. PMID:25163883

  9. Crystallization kinetics and morphology of biodegradable poly(L-lactic acid)/graphene oxide nanocomposites: Influences of graphene oxide loading and crystallization temperature

    International Nuclear Information System (INIS)

    Highlights: ► Biodegradable PLLA/GO nanocomposites at different GO loadings have been prepared. ► Both nonisothermal and isothermal melt crystallization of PLLA are enhanced by GO. ► The crystal structure of PLLA does not change in the PLLA/GO nanocomposites. - Abstract: Biodegradable poly(L-lactic acid) (PLLA)/graphene oxide (GO) nanocomposites have been prepared successfully at various GO loadings. Transmission electron microscopy and wide angle X-ray diffraction results indicate that a relatively fine dispersion of GO is achieved in the PLLA matrix. Nonisothermal melt crystallization peak temperatures are slightly higher in the nanocomposites than in neat PLLA. The overall isothermal melt crystallization rates are reduced for both neat PLLA and the PLLA/GO nanocomposites with increasing crystallization temperature; moreover, the overall isothermal melt crystallization rates are significantly greater in the nanocomposites than in neat PLLA although the crystallization mechanism remains unchanged. The crystal structure of PLLA is not modified in the PLLA/GO nanocomposites. Both the nonisothermal and isothermal melt crystallization of PLLA in the nanocomposites are influenced apparently by the GO loading.

  10. Drug release control in delivery system for biodegradable polymer drugs by γ-radiation

    International Nuclear Information System (INIS)

    Characterizations of the drug release from microsphere and hydrogel preparation made from biodegradable polymers were investigated aiming at development of a drug delivery system which allows an optimum drug delivery and the identification of the factors which control its delivery. Poly-lactic acid microspheres containing 10% of progesterone were produced from poly DL-lactic acid and exposed to γ-ray at 5-1000 kGy. And its glass transition temperature (Tg) was determined by differential scanning calorimetry. The temperature was gradually lowered with an increase in the dose of radiation. Tg of the microsphere exposed at 1000 kGy was lower by 10degC compared with the untreated one, showing that Tg control is possible without changing the size distribution of microsphere. Then, the amount of progesterone released from microsphere was determined. The release rate of the drug linearly increased with a square root of radiation time. These results indicate that the control of drug release rate is possible through controling the microsphere's Tg by γ-ray radiation. (M.N.)

  11. Synthesis and characterization of polymers based on citric acid and glycerol: Its application in non-biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Jaime Alfredo Mariano-Torres

    2015-01-01

    Full Text Available El notable incremento mundial en el consumo de plásticos y su l argo tiempo de residencia en el ambiente muestran la gran neces idad de productos con caracterís ticas biodegradables. En este proyecto fueron desarrollados polímeros biodegradables a base del ácido cítrico y del glicerol. La síntesis de esto s se lleva a cabo a diferentes condiciones de concentración y a temperatura constante. Se des arrollaron mediante un proceso económicamente viable. Se caracterizaron p or medio de las siguientes técnicas: Numero ácido, espectroscop ia infrarroja FTIR, índice de refracc ión, viscosidad, análisis de impacto, ensayo de tensión, dure za, calorimetría, el % de Humed ad (método de la estufa con recirculación de aire, determinación de densi dad, además de pruebas cualitativas para corroborar su biodegra dabilidad. Los polímeros elaborados fueron mezclados con una formulación de PVC grado médico, obteniendo un polímero hibrido y se pudo observar que modifica sus propiedades mecánicas.

  12. Surface Modification of Biodegradable Poly(D,L-lactic acid) by Nitrogen and Nitrogen/Hydrogen Plasma for Improving Surface Hydrophilicity

    International Nuclear Information System (INIS)

    Enhancement of the surface hydrophilicity of biodegradable poly (D,L-lactic acid) (PLA) films is studied. The PLA films were treated by nitrogen plasma (PLA-N2) and nitrogen/hydrogen plasma (PLA-N2/H2), respectively. The surface properties and microstructure of PLA-N2 and PLA-N2/H2 were studied by static contact angle measurement, surface free energy calculation, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is confirmed that the surface hydrophilicity of PLA-N2 and PLA-N2/H2 was higher than that of pristine PLA, and the surface hydrophilicity of PLA-N2 films was better than that of PLA-N2/H2. (plasma technology)

  13. Intimately coupling of photolysis accelerates nitrobenzene biodegradation, but sequential coupling slows biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lihui [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Zhang, Yongming, E-mail: zhym@shnu.edu.cn [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Bai, Qi; Yan, Ning; Xu, Hua [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Rittmann, Bruce E. [Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ 85287-5701 (United States)

    2015-04-28

    Highlights: • Intimately coupled UV photolysis accelerated nitrobenzene biodegradation. • NB biodegradation was slowed by accumulation of nitrophenol. • Oxalic acid was a key product of UV photolysis. • Oxalic acid accelerated biodegradation of nitrobenzene and nitrophenol by a co-substrate effect. • Intimate coupling of UV and biodegradation accentuated the benefits of oxalic acid. - Abstract: Photo(cata)lysis coupled with biodegradation is superior to photo(cata)lysis or biodegradation alone for removal of recalcitrant organic compounds. The two steps can be carried out sequentially or simultaneously via intimate coupling. We studied nitrobenzene (NB) removal and mineralization to evaluate why intimate coupling of photolysis with biodegradation was superior to sequential coupling. Employing an internal circulation baffled biofilm reactor, we compared direct biodegradation (B), biodegradation after photolysis (P + B), simultaneous photolysis and biodegradation (P&B), and biodegradation with nitrophenol (NP) and oxalic acid (OA) added individually and simultaneously (B + NP, B + OA, and B + NP + OA); NP and OA were NB’s main UV-photolysis products. Compared with B, the biodegradation rate P + B was lower by 13–29%, but intimately coupling (P&B) had a removal rate that was 10–13% higher; mineralization showed similar trends. B + OA gave results similar to P&B, B + NP gave results similar to P + B, and B + OA + NP gave results between P + B and P&B, depending on the amount of OA and NP added. The photolysis product OA accelerated NB biodegradation through a co-substrate effect, but NP was inhibitory. Although decreasing the UV photolysis time could minimize the inhibition impact of NP in P + B, P&B gave the fastest removal of NB by accentuating the co-substrate effect of OA.

  14. Intimately coupling of photolysis accelerates nitrobenzene biodegradation, but sequential coupling slows biodegradation

    International Nuclear Information System (INIS)

    Highlights: • Intimately coupled UV photolysis accelerated nitrobenzene biodegradation. • NB biodegradation was slowed by accumulation of nitrophenol. • Oxalic acid was a key product of UV photolysis. • Oxalic acid accelerated biodegradation of nitrobenzene and nitrophenol by a co-substrate effect. • Intimate coupling of UV and biodegradation accentuated the benefits of oxalic acid. - Abstract: Photo(cata)lysis coupled with biodegradation is superior to photo(cata)lysis or biodegradation alone for removal of recalcitrant organic compounds. The two steps can be carried out sequentially or simultaneously via intimate coupling. We studied nitrobenzene (NB) removal and mineralization to evaluate why intimate coupling of photolysis with biodegradation was superior to sequential coupling. Employing an internal circulation baffled biofilm reactor, we compared direct biodegradation (B), biodegradation after photolysis (P + B), simultaneous photolysis and biodegradation (P&B), and biodegradation with nitrophenol (NP) and oxalic acid (OA) added individually and simultaneously (B + NP, B + OA, and B + NP + OA); NP and OA were NB’s main UV-photolysis products. Compared with B, the biodegradation rate P + B was lower by 13–29%, but intimately coupling (P&B) had a removal rate that was 10–13% higher; mineralization showed similar trends. B + OA gave results similar to P&B, B + NP gave results similar to P + B, and B + OA + NP gave results between P + B and P&B, depending on the amount of OA and NP added. The photolysis product OA accelerated NB biodegradation through a co-substrate effect, but NP was inhibitory. Although decreasing the UV photolysis time could minimize the inhibition impact of NP in P + B, P&B gave the fastest removal of NB by accentuating the co-substrate effect of OA

  15. Novel bio-based and biodegradable polymer blends

    Science.gov (United States)

    Yang, Shengzhe

    Most plastic materials, including high performance thermoplastics and thermosets are produced entirely from petroleum-based products. The volatility of the natural oil markets and the increasing cost of petroleum have led to a push to reduce the dependence on petroleum products. Together with an increase in environmental awareness, this has promoted the use of alternative, biorenewable, environmentally-friendly products, such as biomass. The growing interest in replacing petroleum-based products by inexpensive, renewable, natural materials is important for sustainable development into the future and will have a significant impact on the polymer industry and the environment. This thesis involved characterization and development of two series of novel bio-based polymer blends, namely polyhydroxyalkanoate (PHA)/polyamide (PA) and poly(lactic acid) (PLA)/soy protein. Blends with different concentrations and compatible microstructures were prepared using twin-screw extruder. For PHA/PA blends, the poor mechanical properties of PHA improved significantly with an excellent combination of strength, stiffness and toughness by adding PA. Furthermore, the effect of blending on the viscoelastic properties has been investigated using small-amplitude oscillatory shear flow experiments as a function of blend composition and angular frequency. The elastic shear modulus (G‧) and complex viscosity of the blends increased significantly with increasing the concentration of PHA. Blending PLA with soy protein aims at reducing production cost, as well as accelerating the biodegradation rate in soil medium. In this work, the mechanical, thermal and morphological properties of the blends were investigated using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests.

  16. 负载丝裂霉素C的聚乳酸微球制备及对成纤维细胞生长抑制作用研究%Fabrication of Mitomycin C Loaded Polylactic Acid Microspheres and Its Inhibition on Fibroblast Cell Growth

    Institute of Scientific and Technical Information of China (English)

    朱继翔; 彭晔; 田秀梅; 阳范文; 陈晓明

    2014-01-01

    利用单乳化溶剂挥发法制备负载丝裂霉素C( MMC)的聚乳酸( PLA)载药微球.优化载药微球的制备条件,当药物与载体聚合物比例为10∶90时,微球的实际载药量与包封率分别达到最高值5.62%与49.1%;采用SEM对微球形貌进行了表征;对载药微球的体外释药进行研究,结果表明载药微球无明显暴释现象,可有效缓释MMC达30 d以上,累计释放量为84.8%;细胞实验结果表明,载药微球可以有效抑制小鼠NIH-3T3成纤维细胞的增殖.%Mitomycin C ( MMC) loaded polylactic acid ( PLA) microspheres were fabricated by oil-in-water ( O/W) single-emulsion solvent evaporation technique .The preparation conditions were optimized .The results indica-ted that the drug loading rate and encapsulation rate reached maximal values ( 5.62%and 49.1%) when the ratio of MMC to PLA was 10/90.The morphology of microspheres was observed by scanning electron microscopy .The release tests showed that the microspheres could control release MMC over 30 days and the cumulative release was 84.8%in vitro .Microspheres were co-cultured with mouse NIH-3 T3 fibroblast cells and the MTT results showed that the MMC loaded microspheres could effectually inhibit the NIH -3T3 cell growth.

  17. Biodegradable green composites reinforced by the fiber recycling from disposable chopsticks

    International Nuclear Information System (INIS)

    The use of disposable chopsticks is very popular in chopsticks-using countries, such as Taiwan, China and Japan, and is one of the major sources of waste in these countries. In this study, the fiber recycling from disposable chopsticks was chemically modified by coupling agents. Furthermore, the modified fiber was added to the biodegradable polymer (polylactic acid, PLA), to form novel fiber-reinforced green composites. These composites prepared by melt-mixing method, were examined by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and mechanical tests. The results indicated that the Tg of PLA was increased by the addition of fiber, which may improve the heat resistance of PLA. The thermogravimetric analysis of the composites showed that the degradation process of fiber-filled systems started earlier than that of plain PLA, but possessed a higher char yield. Mechanical tests showed that the tensile strength of the composites markedly increased with the fiber content, reaching 115 MPa in the case of being reinforced with 40 phr fiber, which is about 3 times higher as compared to the pristine PLA. Furthermore, this type of reinforced PLA would be more environmental friendly than the artificial additive-reinforced one, and could effectively reduce and reuse the waste of disposable chopsticks.

  18. Construction of a controlled-release delivery system for pesticides using biodegradable PLA-based microcapsules.

    Science.gov (United States)

    Liu, Baoxia; Wang, Yan; Yang, Fei; Wang, Xing; Shen, Hong; Cui, Haixin; Wu, Decheng

    2016-08-01

    Conventional pesticides usually need to be used in more than recommended dosages due to their loss and degradation, which results in a large waste of resources and serious environmental pollution. Encapsulation of pesticides in biodegradable carriers is a feasible approach to develop environment-friendly and efficient controlled-release delivery system. In this work, we fabricated three kinds of polylactic acid (PLA) carriers including microspheres, microcapsules, and porous microcapsules for controlled delivery of Lambda-Cyhalothrin (LC) via premix membrane emulsification (PME). The microcapsule delivery system had better water dispersion than the other two systems. Various microcapsules with a high LC contents as much as 40% and tunable sizes from 0.68 to 4.6μm were constructed by manipulating the process parameters. Compared with LC technical and commercial microcapsule formulation, the microcapsule systems showed a significantly sustained release of LC for a longer period. The LC release triggered by LC diffusion and matrix degradation could be optimally regulated by tuning LC contents and particle sizes of the microcapsules. This multi-regulated release capability is of great significance to achieve the precisely controlled release of pesticides. A preliminary bioassay against plutella xylostella revealed that 0.68μm LC-loaded microcapsules with good UV and thermal stability exhibited an activity similar to a commercial microcapsule formulation. These results demonstrated such an aqueous microcapsule delivery system had a great potential to be further explored for developing an effective and environmentally friendly pesticide-release formulation. PMID:27062215

  19. Recent advances in lactic acid production by microbial fermentation processes.

    Science.gov (United States)

    Abdel-Rahman, Mohamed Ali; Tashiro, Yukihiro; Sonomoto, Kenji

    2013-11-01

    Fermentative production of optically pure lactic acid has roused interest among researchers in recent years due to its high potential for applications in a wide range of fields. More specifically, the sharp increase in manufacturing of biodegradable polylactic acid (PLA) materials, green alternatives to petroleum-derived plastics, has significantly increased the global interest in lactic acid production. However, higher production costs have hindered the large-scale application of PLA because of the high price of lactic acid. Therefore, reduction of lactic acid production cost through utilization of inexpensive substrates and improvement of lactic acid production and productivity has become an important goal. Various methods have been employed for enhanced lactic acid production, including several bioprocess techniques facilitated by wild-type and/or engineered microbes. In this review, we will discuss lactic acid producers with relation to their fermentation characteristics and metabolism. Inexpensive fermentative substrates, such as dairy products, food and agro-industrial wastes, glycerol, and algal biomass alternatives to costly pure sugars and food crops are introduced. The operational modes and fermentation methods that have been recently reported to improve lactic acid production in terms of concentrations, yields, and productivities are summarized and compared. High cell density fermentation through immobilization and cell-recycling techniques are also addressed. Finally, advances in recovery processes and concluding remarks on the future outlook of lactic acid production are presented. PMID:23624242

  20. Biodegradation kinetics at low concentrations (

    DEFF Research Database (Denmark)

    Toräng, Lars; Albrechtsen, Hans-Jørgen; Nyholm, Niels

    Aerobic biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in groundwater added sediment fines. At concentrations at or below 1 mu g/L of 2,4-D degradation kinetic was of true first order without significant growth of specific degraders and with half-life for mineralization in the...

  1. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, Yasko; Machado, Luci D.B., E-mail: ykodama@ipen.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Oishi, Akihiro; Nakayama, Kazuo, E-mail: a.oishi@aist.go.j, E-mail: kazuo-nakayama@jcom.home.ne.j [National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki-ken (Japan). Research Institute for Sustainable Chemical Innovation; Nagasawa, Naotsugu; Tamada, Masao, E-mail: nagasawa.naotsugu@jaea.go.j [Japan Atomic Energy Agency (JAEA), Gunma-ken (Japan). Quantum Beam Science Directorate

    2009-07-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  2. Biodegradable PLGA-b-PEG polymeric nanoparticles: synthesis, properties, and nanomedical applications as drug delivery system

    International Nuclear Information System (INIS)

    During the past decades many synthetic polymers have been studied for nanomedicine applications and in particular as drug delivery systems. For this purpose, polymers must be non-toxic, biodegradable, and biocompatible. Polylactic-co-glycolic acid (PLGA) is one of the most studied polymers due to its complete biodegradability and ability to self-assemble into nanometric micelles that are able to entrap small molecules like drugs and to release them into body in a time-dependent manner. Despite fine qualities, using PLGA polymeric nanoparticles for in vivo applications still remains an open challenge due to many factors such as poor stability in water, big diameter (150–200 nm), and the removal of these nanocarriers from the blood stream by the liver and spleen thus reducing the concentration of drugs drastically in tumor tissue. Polyethylene glycol (PEG) is the most used polymers for drug delivery applications and the first PEGylated product is already on the market for over 20 years. This is due to its stealth behavior that inhibits the fast recognition by the immune system (opsonization) and generally leads to a reduced blood clearance of nanocarriers increasing blood circulation time. Furthermore, PEG is hydrophilic and able to stabilize nanoparticles by steric and not ionic effects especially in water. PLGA–PEG block copolymer is an emergent system because it can be easily synthesized and it possesses all good qualities of PLGA and also PEG capability so in the last decade it arose as one of the most promising systems for nanoparticles formation, drug loading, and in vivo drug delivery applications. This review will discuss briefly on PLGA-b-PEG synthesis and physicochemical properties, together with its improved qualities with respect to the single PLGA and PEG polymers. Moreover, we will focus on but in particular will treat nanoparticles formation and uses as new drug delivery system for nanomedical applications.

  3. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    International Nuclear Information System (INIS)

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  4. Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

    Science.gov (United States)

    Cha, Kyoung Je; Kim, Taewan; Jea Park, Sung; Kim, Dong Sung

    2014-11-01

    Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications.

  5. Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

    Directory of Open Access Journals (Sweden)

    S. H. Jafari

    2013-01-01

    Full Text Available Polylactic acid (PLA/linear low density polyethylene (LLDPE blend nanocomposites based on two different commercial-grade nanoclays, Cloisite® 30B and Cloisite® 15A, were produced via different melt mixing procedures in a counter-rotating twin screw extruder. The effects of mixing sequence and clay type on morphological and rheological behaviors as well as degradation properties of the blends were investigated. The X-ray diffraction (XRD results showed that generally the level of exfoliation in 30B based nanocomposites was better than 15A based nanocomposites. In addition, due to difference in hydrophilicity and kind of modifiers in these two clays, the effect of 30B on refinement of dispersed phase and enhancement of biodegradability of PLA/LLDPE blend was much more remarkable than that of 15A nanoclay. Unlike the one step mixing process, preparation of nanocomposites via a two steps mixing process improved the morphology. Based on the XRD and TEM (transmission electron microscopic results, it is found that the mixing sequence has a remarkable influence on dispersion and localization of the major part of 30B nanoclay in the PLA matrix. Owing to the induced selective localization of nanoclays in PLA phase, the nanocomposites prepared through a two steps mixing sequence exhibited extraordinary biodegradability, refiner morphology and better melt elasticity.

  6. Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

    International Nuclear Information System (INIS)

    Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications. (paper)

  7. Cellulose sulphuric acid as a biodegradable catalyst for conversion of aryl amines into azides at room temperature under mild conditions

    Indian Academy of Sciences (India)

    Firouzeh Nesmati; Ali Elhampour

    2012-07-01

    This article describes simple and efficient method for the diazotization and azidation of different aromatic amines over cellulose sulphuric acid, sodium nitrite and sodium azide under mild conditions at room temperature. Various aryl amines possessing electron-withdrawing groups or electron-donating groups have been converted into the corresponding aryl azides with 71-99% yields. The use of mild reaction conditions, avoids the use of harmful acids and toxic solvents and short reaction times are advantages of this methodology. The selected catalyst is found to be highly efficient and recyclable.

  8. INCLUSION COMPLEX FORMATION BETWEEN α-CYCLODEXTRIN AND BIODEGRADABLE COMBLIKE COPOLYMERS WITH POLY(α,β-MALIC ACID) BACKBONES AND mPEG SIDE CHAINS

    Institute of Scientific and Technical Information of China (English)

    Jing Zeng; Yuan Li; Jia-jing Li; Rui Wang; Bin He; Yu Nie; Xiang-lin Luo; Zhi-rong Zhang; Zhong-wei Gua

    2009-01-01

    Inclusion complexes(ICs)composed of ocyclodextrins(α-CD)and biodegradable comblike copolymers with poly(α,β-malic acid)(PMA)backbones and methylated poly(ethylene glycol)(mPEG)side chains were prepared by the host-guest reaction.Two series of ICs with mPEG750 and mPEG2000 were prepared.The stoichiometry(EG/CD)of all the ICs in mPEG2000 series was 3.1,no matter what the graft degree was.While in mPEG750 series,the stoichiometry(EG/CD)was very different;it increased with the amount of mPEG decreasing.The decomposition temperatures of the fragments in ICs were closely related to graft degrees.The stack of α-CDs in ICs was a channel-type structure.The crystal of ICs was lamellar,and it could be reorganized to well-defined supermolecular structure.

  9. Development of novel antibacterial active, HaCaT biocompatible and biodegradable CA-g-P(3HB-EC biocomposites with caffeic acid as a functional entity

    Directory of Open Access Journals (Sweden)

    H. M. N. Iqbal

    2015-09-01

    Full Text Available We have developed novel composites by grafting caffeic acid (CA onto the P(3HB-EC based material and laccase from Trametes versicolor was used for grafting purposes. The resulting composites were designated as CA-g-P(3HB-EC i.e., P(3HB-EC (control, 5CA-g-P(3HB-EC, 10CA-g-P(3HB-EC, 15CA-g-P(3HB-EC and 20CA-g-P(3HB-EC. FT-IR (Fourier-transform infrared spectroscopy was used to examine the functional and elemental groups of the control and laccase-assisted graft composites. Evidently, 15CA-g-P(3HB-EC composite exhibited resilient antibacterial activity against Gram-positive and Gram-negative bacterial strains. Moreover, a significant level of biocompatibility and biodegradability of the CA-g-P(3HB-EC composites was also achieved with the human keratinocytes-like HaCaT cells and soil burial evaluation, respectively. In conclusion, the newly developed novel composites with multi characteristics could well represent the new wave of biomaterials for medical applications, and more specifically have promising future in the infection free would dressings, burn and/or skin regeneration field due to their sophisticated characteristics.

  10. Regeneration of three-way automobile catalysts using biodegradable metal chelating agent-S, S-ethylenediamine disuccinic acid (S, S-EDDS)

    International Nuclear Information System (INIS)

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various contaminants such as P, Zn, Pb, Cu and S from commercial aged three-way catalysts, and improving their catalytic performance towards CO and NO pollutants removal has been investigated. Four samples of catalysts from the front and rear inlets of two different TWCs with different mileages and aged under completely different driving conditions were investigated. The catalysts were characterized using various techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements (N2 adsorption at 77 K). Quantitative ICP-MS analyses and SEM-EDS studies show the removal of Zn, P and Pb. SEM-EDS images obtained at low magnification (50 μm) showed considerable differences in the surface morphology and composition after washing with S, S-EDDS. However, XRD studies indicated neither little to no removal of major contaminant compound phases nor major structural changes due to washing. Correspondingly, little or no enhancement in BET surface area was observed between the used and washed samples. Light-off curves show that the regeneration procedure employed can effectively improve the catalytic performance towards NO pollutant.

  11. Synthesis and Characterization of a Biodegradable Copolymer: RGD Peptide Modification of Poly (lactic acid-co-lysine)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The poly ( lactic acid- co-lysine ) was synthesized using IR and 1 H NMR to characterize the copolymer. And then the RGD modification copolymer RGD-PLAL was prepared. The contact angles were used to see the RGD modification occurrence. Also high molecular weight polymer was controlled to the reaction of polymerization of copolymer.

  12. Proceedings of biodegradation

    International Nuclear Information System (INIS)

    This book contains the proceedings of Biodegradation. Topics include:biodegradation using the tools of biotechnology, basic science aspects of biodegradation, the physiological characteristics of microorganisms, the use of selective techniques that enhance the process of microbial evolution of biodegradative genes in nature, the genetic characteristics of microorganisms allowing them to biodegrade both natural and synthetic toxic chemicals, the molecular techniques that allow selective assembly of genetic segments form a variety of bacterial strains to a single strain, and methods needed to advance biodegradation research as well as the high-priority chemical problems important to the Department of Defense or to the chemical industry

  13. An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

    OpenAIRE

    Quanxuan Zhang; Hong Ren; Baker, Gregory L.

    2014-01-01

    2-Hydroxy-4-pentynoic acid (1) is a key intermediate towards ‘clickable’ polylactide which allows for efficient introduction of a broad range of pendant functional groups onto polymers from a single monomer via convenient ‘click’ chemistry with organic azides. The incorporation of various pendant functional groups could effectively tailor the physicochemical properties of polylactide. The reported synthesis of 1 started from propargyl bromide and ethyl glyoxylate. However, both of starting ma...

  14. Mechanical performance evaluation of bionanocomposites with polymeric matrix of poly(lactic acid)-PLA and organo clay; Avaliacao do comprtamento mecanico de bionanocompositos com patriz polimerica de poli(acido latico)-PLA e argila organofilica

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcanti, Shirley N.; Melo, Tomas J.A. de; Araujo, Edcleide M.; Oliveira, Akidauana D.A.; Lima, Jessica C.C., E-mail: shirleynobre@gmail.com [Universidade Federal de Campina Grande - UFCG - Dept. de Engenharia de Materiais, Campina Grande, PB (Brazil)

    2011-07-01

    The aim of this study is to evaluate the influence of ethylene/methyl acrylate (EMA) and ethylene/glycidyl methacrylate (E-GMA) copolymers and organoclay on the mechanical properties of polymer PLA-poly (lactic acid), from the system PLA / organoclay. The clay was organophilized with the ionic surfactant praepagem and the mixtures were prepared in a modular twin screw extruder. The behavior of bionanocomposites was evaluated by tensile and impact tests. The results of FTIR and DR-X indicated that the process was efficient organophilization. The mechanical properties showed that the elastic modulus and tensile strength of bionanocomposites obtained decreased compared to PLA. On the other hand there was a gain for resistance to impact, for all systems except for system PLA/OMMT. (author)

  15. Fabrication of a three-dimensional tissue model microarray using laser foaming of a gas-impregnated biodegradable polymer

    International Nuclear Information System (INIS)

    A microarray containing three-dimensional (3D) tissue models is a promising substitute for the two-dimensional (2D) cell-based microarrays currently available for high throughput, tissue-based biomedical assays. A cell culture microenvironment similar to in vivo conditions could be achieved with biodegradable porous scaffolds. In this study, a laser foaming technique is developed to create an array of micro-scale 3D porous scaffolds. The effects of major process parameters and the morphology of the resulting porous structure were investigated. For comparison, cell culture studies were conducted with both foamed and unfoamed samples using T98G cells. The results show that by laser foaming gas-impregnated polylactic acid it is possible to generate an array of inverse cone shaped wells with porous walls. The size of the foamed region can be controlled with laser power and exposure time, while the pore size of the scaffold can be manipulated with the saturation pressure. T98G cells grow well in the foamed scaffolds, forming clusters that have not been observed in 2D cell cultures. Cells are more viable in the 3D scaffolds than in the 2D cell culture cases. The 3D porous microarray could be used for parallel studies of drug toxicity, guided stem cell differentiation, and DNA binding profiles. (paper)

  16. Impact Strength and Flexural Properties Enhancement of Methacrylate Silane Treated Oil Palm Mesocarp Fiber Reinforced Biodegradable Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Chern Chiet Eng

    2014-01-01

    Full Text Available Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA/polycaprolactone (PCL/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA, and scanning electron microscopy (SEM. FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

  17. Size-controlled synthesis of biodegradable nanocarriers for targeted and controlled cancer drug delivery using salting out cation

    Indian Academy of Sciences (India)

    Madasamy Hari Balakrishanan; Mariappan Rajan

    2016-02-01

    Research for synthesis of size-controlled carriers is currently challenging one. In this research paper, a method for size-controlled synthesis of biodegradable nanocarriers is proposed and described. Salting out method is suitable for both hydrophilic and hydrophobic drugs for the encapsulation on carriers. This synthetic method is based on polylactic acid (PLA) and non-ionic carboxymethyl cellulose (CMC) composed by CaCl2 as salting out agent. This method permits size-controlled synthesis of particles between 50 and 400 nm simply by varying the concentration of salting out agents. We have prepared cisplatin (CDDP)-loaded PLA-CMC nanocarriers by salting out method, with varying salting out agent (CaCl2) concentrations as 0.05, 0.2, 0.35 and 0.5 M. The nanocarriers were characterized for their size, surface charge and morphology by atomic force microscope, zeta potential analyser and transmission electron microscope, respectively. The encapsulation efficiency and in-vitro drug-releasing behaviour of the nanocarriers were investigated. The cytotoxicity effect of nanocarriers and drug-loaded nanocarriers was tested against MCF-7 breast cancer cell line.

  18. Effect of platy and tubular nanoclays on behaviour of biodegradable PCL/PLA blend and related microfibrillar composites

    Science.gov (United States)

    Kelnar, Ivan; Kratochvíl, Jaroslav

    2016-05-01

    Blending of ductile poly(ɛ-caprolactone) (PCL) and rigid polylactic acid (PLA) is a promising way to tailor biodegradable materials with broad range of properties. But the mutual incompatibility of both polyesters leads to compromised behaviour only. Alternative to PCL/PLA blends is application of PLA in the form of short fibres, however, difficult dispergation of flexible fibres including their poor adhesion and limited processing is a significant restriction. More effective is in situ formation of polymeric fibre-reinforced materials using microfibrillar composites (MFC) concept based on melt- or cold-drawing of a polymer blend. Important advantage of MFC is efficient dispersion and bonding of in-situ formed reinforcing fibres This work deals with combination of structure-directing and reinforcing effects of montmorillonite (oMMT) and halloysite nanotubes (HNT) in the PCL/PLA 80/20 blend with in-situ formation of PLA fibrils in the PCL matrix. In the resulting microfibrillar composite, reinforcement by rigid PLA fibrils is combined with strengthening of both components by the nanofiller (NF). Moreover, PLA fibrils formation via melt-drawing is only possible after nanofiller addition due to favourable affecting of rheological parameters of the polymer components. The structure-properties relationship and complex effect of NF on microfibrillar composite performance, causing e.g., quite comparable parameters of both microfibrillar composites in spite of lower reinforcing effect of halloysite nanotubes on components, are discussed.

  19. Hybrid coating on a magnesium alloy for minimizing the localized degradation for load-bearing biodegradable mini-implant applications

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au; Liyanaarachchi, S.

    2013-10-01

    The effect of a hybrid coating, calcium phosphate (CaP) + polylactic acid (PLA), on a magnesium alloy on its in vitro degradation (general and localized) behaviour was studied for potential load-bearing biodegradable mini-implant applications. CaP was coated on a magnesium alloy, AZ91, using an electrochemical deposition method. A spin coating method was used to coat PLA on the CaP coated alloy. In vitro degradation performance of the alloy with hybrid coating was evaluated using electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). The EIS results showed that the hybrid coating enhanced the degradation resistance of the alloy by more than two-order of magnitude as compared to the bare alloy and one-order of magnitude higher than that of the CaP coated alloy, after 1 h exposure in simulated body fluid (SBF). Long-term (48 h) EIS results also confirmed that the hybrid coating performed better than the bare alloy and the CaP coated alloy. Importantly, the hybrid coating improved the localized degradation resistance of the alloy significantly, which is critical for better in service mechanical integrity. - Highlights: • A hybrid coating (CaP + PLA) was applied on a magnesium-based alloy. • The hybrid coating enhanced the in vitro degradation resistance of the alloy. • Localized degradation resistance was also improved by the hybrid coating.

  20. Hybrid coating on a magnesium alloy for minimizing the localized degradation for load-bearing biodegradable mini-implant applications

    International Nuclear Information System (INIS)

    The effect of a hybrid coating, calcium phosphate (CaP) + polylactic acid (PLA), on a magnesium alloy on its in vitro degradation (general and localized) behaviour was studied for potential load-bearing biodegradable mini-implant applications. CaP was coated on a magnesium alloy, AZ91, using an electrochemical deposition method. A spin coating method was used to coat PLA on the CaP coated alloy. In vitro degradation performance of the alloy with hybrid coating was evaluated using electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). The EIS results showed that the hybrid coating enhanced the degradation resistance of the alloy by more than two-order of magnitude as compared to the bare alloy and one-order of magnitude higher than that of the CaP coated alloy, after 1 h exposure in simulated body fluid (SBF). Long-term (48 h) EIS results also confirmed that the hybrid coating performed better than the bare alloy and the CaP coated alloy. Importantly, the hybrid coating improved the localized degradation resistance of the alloy significantly, which is critical for better in service mechanical integrity. - Highlights: • A hybrid coating (CaP + PLA) was applied on a magnesium-based alloy. • The hybrid coating enhanced the in vitro degradation resistance of the alloy. • Localized degradation resistance was also improved by the hybrid coating