Plasma surface modification of poly (L-lactic acid) and poly (lactic-co-glycolic acid) films for improvement of nerve cells adhesion

International Nuclear Information System (INIS)

Khorasani, M.T.; Mirzadeh, H.; Irani, S.

2008-01-01

Radio frequency (RF) plasma treatment in O 2 was applied to modify the surface of poly (L-lactic acid) (PLLA) and poly (D,L-lactic acid-coglycolic acid) (PLGA) as biodegradable polymers. The surface structure, morphology, wettability and surface chemistry of treated films were characterized by water drop contact angle measurement, scanning electron microscope (SEM), optical invert microscope, differential scanning calorimetry (DSC) and ATIR-FTIR spectroscopy. The cell affinity of the oxygen plasma treated film was evaluated by nervous tissue B65 cell culture in stationary conditions. The results showed that the hydrophilicity increased greatly after O 2 plasma treatment. The results showed that improved cell adhesion was attributed to the combination of surface chemistry and surface wettability during plasma treatment. Cell culture results showed that B65 nervous cell attachment and growth on the plasma treated PLLA was much higher than an unmodified sample and PLGA. Surface hydrophilicity and chemical functional groups with high polar component play an important role in enhancing cell attachment and growth

Thermal properties of poly (lactic acid)/milkweed composites

Science.gov (United States)

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

Electrospinnability of poly lactic-co-glycolic acid (PLGA)

DEFF Research Database (Denmark)

Liu, Xiaoli; Baldursdottir, Stefania G.; Aho, Johanna

2017-01-01

PURPOSE: In this study, the electrospinnability of poly(lactic-co-glycolic acid) (PLGA) solutions was investigated, with a focus on understanding the influence of molecular weight of PLGA, solvent type and solvent composition on the physical properties of electrospun nanofibers. METHOD: Various s...

Functional Properties of Plasticized Bio-Based Poly(Lactic Acid)_Poly(Hydroxybutyrate) (PLA_PHB) Films for Active Food Packaging

OpenAIRE

Burgos, Nuria; Armentano, Ilaria; Fortunati, Elena; Dominici, Franco; Luzi, Francesca; Fiori, Stefano; Cristofaro, Francesco; Visai, Livia; Jiménez, Alfonso; Kenny, José María

2017-01-01

Fully bio-based and biodegradable active films based on poly(lactic acid) (PLA) blended with poly(3-hydroxybutyrate) (PHB) and incorporating lactic acid oligomers (OLA) as plasticizers and carvacrol as active agent were extruded and fully characterized in their functional properties for antimicrobial active packaging. PLA_PHB films showed good barrier to water vapor, while the resistance to oxygen diffusion decreased with the addition of OLA and carvacrol. Their overall migration in aqueous f...

Styrene-Assisted Maleic Anhydride Grafted Poly(lactic acid as an Effective Compatibilizer for Wood Flour/Poly(lactic acid Bio-Composites

Directory of Open Access Journals (Sweden)

Jun Du

2017-11-01

Full Text Available This study aimed to evaluate the effect of styrene-assisted maleic anhydride-grafted poly(lactic acid (PLA-g-St/MAH on the interfacial properties of wood flour/poly(lactic acid (PLA bio-composites. PLA-g-St/MAH was synthesized by free-radical melt grafting using styrene as a comonomer and dicumyl peroxide as an initiator. The structure of PLA-g-St/MAH was characterized by Fourier transform infrared spectroscopy. Wood flour/PLA composites were prepared by compression molding using PLA-g-St/MAH as a compatibilizer. The effects of PLA-g-St/MAH on the rheological and mechanical properties, as well as on the fractured surface morphology of the composites were investigated. Results indicated that storage modulus, complex viscosity, equilibrium torque, and shear heat were significantly increased. The mechanical properties of the wood flour/PLA composites were also significantly increased after the addition of PLA-g-St/MAH. The maximum values were achieved at the loading rate of 3 wt % because of the improved interfacial adhesion between the wood flour and the PLA matrix.

Lactic acid production by irradiated Bacillus NF17 and poly-L-lactate biopolymer formation

International Nuclear Information System (INIS)

Tongpim, Saowanit; Poonsawat, Choosak; Khansawai, Paveena; Piadaeng, Nattaya

2006-09-01

This study was conducted to manipulate the thermo tolerant, lactic acid-producing bacteria, Bacillus coagulans strain NF 1 7, in the production of L-lactic acid and a bio polymer: poly-L-lactate. The bacterial isolate NF 1 7 kept in the culture collection of Khon Kaen University and could tolerate high temperature and produce lactic acid, was employed in this research work. Cell suspension of isolate NF 1 7 was exposed to gamma irradiation at various doses (1-5 KGy). The irradiated survivors were screened on the basis of forming larger colonies and clear zones than the parent strain NF 1 7 when grown on Glucose-Yeast extract-Peptone (GYP) containing CaCO 3 . We obtained 55 effective isolates which the isolate L5I2-14(5), designated as K 1 4, was chosen together with the parent strain NF 1 7 for fermentation experiments. Each bacterial strain was inoculated into GYP broth and incubated statically at 50 o C with daily pH neutralization. After 5 days of incubation, the isolate K 1 4 and NF 1 7 produced 9.71 g/l and 7.42 g/l of L-lactic acid, respectively with a small amount of D-lactic acid. Lactic acid production from sugar cane molasses by batch fermentation of Bacillus Sp. K 1 4 was carried out in a 7 l jar fermentor containing 5 l of fermentation medium. It was found that 20% molasses with the agitation speed of 100 rpm gave the highest yield of lactic acid. Poly-L-lactic acid was chemically polymerized by bulk polymerization process at 140 o C under 40 mmHg conditions. We could obtain the off-white polymer in a small amount of powder form. Improvement the yield of poly-L-lactic acid would be achieved by using polyisoprene-g-polyvinyl monomer to separate lactic acid from the fermenting liquid prior to polymerization processes

Catalytic Cracking of Lactide and Poly(Lactic Acid) to Acrylic Acid at Low Temperatures.

Science.gov (United States)

Terrade, Frédéric G; van Krieken, Jan; Verkuijl, Bastiaan J V; Bouwman, Elisabeth

2017-05-09

Despite being a simple dehydration reaction, the industrially relevant conversion of lactic acid to acrylic acid is particularly challenging. For the first time, the catalytic cracking of lactide and poly(lactic acid) to acrylic acid under mild conditions is reported with up to 58 % yield. This transformation is catalyzed by strong acids in the presence of bromide or chloride salts and proceeds through simple S N 2 and elimination reactions. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Topological characterization of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites

Science.gov (United States)

Bhat, A. H.; Dasan, Y. K.; Khan, Ihsan Ullah; Ahmad, Faiz; Ayoub, Muhammad

2016-11-01

This study was conducted to evaluate the morphological and barrier properties of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites. Nanocrystalline cellulose was isolated from waste oil palm empty fruit bunch fiber using Sulphuric acid hydrolysis. Chemical modifications of nanocrystalline cellulose was performed to allow good compatibilization between fiber and the polymer matrices and also to improve dispersion of fillers. Bionanocomposite materials were produced from these nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) using solvent casting and evaporation techniques. The properties of extracted nanocrystalline cellulose were examined using FT-IR spectroscopy, X-ray diffractometer, TEM and AFM. Besides that, the properties of bionanocomposites were examined through FESEM and oxygen permeability properties analysis. Better barrier and morphological properties were obtained for nanocrystalline cellulose reinforced bionanocomposites than for neat polymer blend.

Prolonged local anesthetic action through slow release from poly (lactic acid co castor oil).

Science.gov (United States)

Sokolsky-Papkov, Marina; Golovanevski, Ludmila; Domb, Abraham J; Weiniger, Carolyn F

2009-01-01

To evaluate a new formulation of bupivacaine loaded in an injectable fatty acid based biodegradable polymer poly(lactic acid co castor oil) in prolonging motor and sensory block when injected locally. The polyesters were synthesized from DL: -lactic acid and castor oil with feed ratio of 4:6 and 3:7 w/w. Bupivacaine was dispersed in poly(fatty ester) liquid and tested for drug release in vitro. The polymer p(DLLA:CO) 3:7 loaded with 10% bupivacaine was injected through a 22G needle close to the sciatic nerve of ICR mice and the duration of sensory and motor nerve blockade was measured. The DL: -lactic acid co castor oil p(DLLA:CO) 3:7 released 65% of the incorporated bupivacaine during 1 week in vitro. Single injection of 10% bupivacaine loaded into this polymer caused motor block that lasted 24 h and sensory block that lasted 48 h. Previously we developed a ricinoleic acid based polymer with incorporated bupivacaine which prolonged anesthesia to 30 h. The new polymer poly(lactic acid co castor oil) 3:7 provides slow release of effective doses of the incorporated local anesthetic agent and prolongs anesthesia to 48 h.

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...

Piezoelectric antibacterial fabric comprised of poly(l-lactic acid) yarn

Science.gov (United States)

Ando, Masamichi; Takeshima, Satoshi; Ishiura, Yutaka; Ando, Kanako; Onishi, Osamu

2017-10-01

A lactic acid monomer has an asymmetric carbon in the molecule, so there are optical isomer l- and d-type. The most widely used poly(lactic acid) (PLA) for commercial applications is poly(l-lactic acid) (PLLA). PLLA is the polymerization product of l-lactide. Certain treatments of PLLA can yield a film that exhibits shear piezoelectricity. Thus, piezoelectric PLLA fiber can be generated by micro slitting piezoelectric PLLA films or by a melt spinning method. We prepared left-handed helical multi fiber yarn (S-yarn) and right-handed helical yarn (Z-yarn) using piezoelectric PLLA fiber. PLLA exhibited shear mode piezoelectricity, causing the electric polarity of the yarn surface to be reversed on the S-yarn and Z-yarn when tension was applied. An SZ-yarn was produced by combining the S-yarn and Z-yarn, and fabric was prepared using the SZ-yarn. This study demonstrated that the fabric has a strong antibacterial effect, which is thought to be due to the strong electric field between the yarns. The field is generated by a piezoelectric effect when the fabric was extended and contracted.

Properties of poly(lactic acid)/hydroxyapatite composite through the use of epoxy functional compatibilizers for biomedical application.

Science.gov (United States)

Monmaturapoj, Naruporn; Srion, Autcharaporn; Chalermkarnon, Prasert; Buchatip, Suthawan; Petchsuk, Atitsa; Noppakunmongkolchai, Warobon; Mai-Ngam, Katanchalee

2017-08-01

A composite of 70/30 poly(lactic acid)/hydroxyapatite was systematically prepared using various amounts of glycidyl methacrylate as reactive compatibilizer or Joncryl ADR®-4368 containing nine glycidyl methacrylate functions as a chain extension/branching agent to improve the mechanical and biological properties for suitable usage as internal bone fixation devices. The effect of glycidyl methacrylate/Joncryl on mechanical properties of poly(lactic acid)/hydroxyapatite was investigated through flexural strength. Cell proliferation and differentiation of osteoblast-like MC3T3-E1 cells cultured on the composite samples were determined by Alamar Blue assay and alkaline phosphatase expression, respectively. Result shows that flexural strength tends to decrease, as glycidyl methacrylate content increases except for 1 wt.% glycidyl methacrylate. With an addition of dicumyl peroxide, the flexural strength shows an improvement than that of without dicumyl peroxide probably due to the chemical bonding of the hydroxyapatite and poly(lactic acid) as revealed by FTIR and NMR, whereas the composite with 5 wt.% Joncryl shows the best result, as the flexural strength increases getting close to pure poly(lactic acid). The significant morphology change could be seen in composite with Joncryl where the uniform agglomeration of hydroxyapatite particles oriented in poly(lactic acid) matrix. Addition of the epoxy functional compatibilizers at suitable percentages could also have benefits to cellular attachment, proliferation, differentiation and mineralization. So that, this poly(lactic acid)/hydroxyapatite composite could be a promising material to be used as internal bone fixation devices such as screws, pins and plates.

Blends of low molecular weight of poly lactic acid (PLA) with gondorukem (gum rosin)

Science.gov (United States)

Kaavessina, Mujtahid; Distantina, Sperisa; Chafidz, Achmad; Utama, Aditya; Anggraeni, Venisa Mega Puteri

2018-02-01

The utilization of plastic was increasing as well as the increasing its demand in wide range application. Consequently, the number of plastic litter will increase and make more serious environmental problems. This research concerns to minimize waste problems by designing biodegradable plastic. In this research, biodegradable plastic was made of poly lactic acid (PLA) and gondorukem (Gum rosin, Resina colophonium) as the plasticizer. The effect of gondorukem towards PLA properties such as rheology and degradability was investigated. The research divided into two steps: (i) the polycondensation of lactic acid (LA) and (ii) modification of obtained poly lactic acid. In the first step, polycondensation was done in N2 atmosphere (138°C) for 30 hours and added 0.1 %w of SnCl2 as catalyst. Bulk modification was conducted by blending of gondurukem in varied weight (0.5, 1, and 2 g in 10 g of PLA). Furthermore, the modified PLA was analyzed its molecular structure, biodegradability and rheological property. The presence of gondorukem enhanced the biodegradability of poly lactic acid. Gondorukem could act as the plasticizer. It is confirmed that the complex viscosity of PLA melt decreased upon the addition of gondorukem

Separation and purification of lactic acid. Thermal catalytic depolymerization of poly-lactic acid into lactide; Hakkoho nyusan no bunri seisei ni kansuru kenkyu. Pori nyusan no rakuchido eno sesshokuteki netsukai jugo

Energy Technology Data Exchange (ETDEWEB)

Morita, M.; Hirama, Y.; Liew, M. [Hokkaido National Industrial Research Institute, Sapporo (Japan)

1996-05-10

A new separation and purification method for lactic acid from fermentation broth is proposed by which poly-lactic acid produced from unpurified lactic acid is catalytically depolymerized into lactide fractions then further purified into lactide. In the present study, thermal depolymerization catalysts were investigated for commercial use. Iron catalysts, especially metallic iron, and ferrous oxide and lactate, were found to provide almost the same catalytic activity and lactide composition in depolymerization products and those in tin octoate and antimony oxide catalysts. Ferrous oxide was also applied to depolymerize poly-lactic acid derived form unpurified lactic acid to compare catalytic activity and lactide composition and was confirmed to show results similar to those of pure polymer. Based on these findings, it is concluded that iron catalysts can be used commercially. Furthermore, catalytic depolymerization of poly-lactic acids with different molecular weights were studied. Polymers with Mw 5,000-10,000 were found to be better for production of lactide, based on the behavior of depolymerization and lactide content in the product. 5 refs., 9 figs., 1 tab.

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

Effect of l-lysine-assisted surface grafting for nano-hydroxyapatite on mechanical properties and in vitro bioactivity of poly(lactic acid-co-glycolic acid).

Science.gov (United States)

Liuyun, Jiang; Lixin, Jiang; Chengdong, Xiong; Lijuan, Xu; Ye, Li

2016-01-01

It is promising and challenging to study surface modification for nano-hydroxyapatite to improve the dispersion and enhance the mechanical properties and bioactivity of poly(lactic acid-co-glycolic acid). In this paper, we designed an effective new surface grafting with the assist of l-lysine for nano-hydroxyapatite, and the nano-hydroxyapatite surface grafted with the assist of l-lysine (g-nano-hydroxyapatite) was incorporated into poly(lactic acid-co-glycolic acid) to develop a series of g-nano-hydroxyapatite/poly(lactic acid-co-glycolic acid) nano-composites. The surface modification reaction for nano-hydroxyapatite, the mechanical properties, and in vitro human osteoblast-like cell (MG-63) response were characterized and investigated by Fourier transformation infrared, thermal gravimetric analysis, dispersion test, electromechanical universal tester, differential scanning calorimeter measurements, and in vitro cells culture experiment. The results showed that the grafting amount on the surface of nano-hydroxyapatite was enhanced with the increase of l-lysine, and the dispersion of nano-hydroxyapatite was improved more, so that it brought about better promotion crystallization and more excellent mechanical enhancement effect for poly(lactic acid-co-glycolic acid), comparing with the unmodified nano-hydroxyapatite. Moreover, the cells' attachment and proliferation results confirmed that the incorporation of the g-nano-hydroxyapatite into poly(lactic acid-co-glycolic acid) exhibited better biocompatibility than poly(lactic acid-co-glycolic acid). The above results indicated that the new surface grafting with the assist of l-lysine for nano-hydroxyapatite was an ideal novel surface modification method, which brought about better mechanical enhancement effect and in vitro bioactivity for poly(lactic acid-co-glycolic acid) with adding higher g-nano-hydroxyapatite content, suggesting it had a great potential to be used as bone fracture internal fixation materials

Characterisation of poly(lactic acid): poly(ethyleneoxide) (PLA:PEG) nanoparticles using the self-consistent theory modelling approach

NARCIS (Netherlands)

Heald, C.R.; Stolnik, S.; Matteis, De C.; Garnett, M.C.; Illum, L.; Davis, S.S.; Leermakers, F.A.M.

2003-01-01

Self-consistent field (SCF) modelling studies can be used to predict the properties of poly(lactic acid):poly(ethyleneoxide) (PLA:PEG) nanoparticles using the theory developed by Scheutjens and Fleer. Good agreement in the results between experimental and modelled data has been observed previously

Biodegradable Poly(D,L-lactic-co-glycolic acid)-Based Micro ...

African Journals Online (AJOL)

... drug encapsulation efficiency and release profile of PLGA mico/nanoparticles. The current knowledge of protein instability during preparation, storage and release from PLGA micro/nanoparticles and protein stabilization approaches has also been discussed in this review. Keywords: Poly(D, L-lactic-co-glycolic acid), ...

Starch/fiber/poly(lactic acid) foam and compressed foam composites

Science.gov (United States)

Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were compressed into plastics using force ranging from 4-76MPa. Te...

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

International Nuclear Information System (INIS)

Chen Chen; Lv Gang; Pan Chao; Song Min; Wu Chunhui; Guo Dadong; Wang Xuemei; Chen Baoan; Gu Zhongze

2007-01-01

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 TiO 2 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-TiO 2 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)

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.

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

Science.gov (United States)

Quiroz-Castillo, Jesús Manuel; Rodríguez-Félix, Dora Evelia; Grijalva-Monteverde, Heriberto; Lizárraga-Laborín, Lauren Lucero; Castillo-Ortega, María Mónica; del Castillo-Castro, Teresa; Rodríguez-Félix, Francisco; Herrera-Franco, Pedro Jesús

2014-01-01

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. PMID:28787928

Analysis of Poly(Lactic-co-Glycolic Acid/Poly(Isoprene Polymeric Blend for application as biomaterial

Directory of Open Access Journals (Sweden)

Douglas Ramos Marques

2013-01-01

Full Text Available The application of renewable raw materials encourages research in the biopolymers area. The Poly(Lactic-co-Glycolic Acid/Poly(Isoprene (PLGA/IR blend combines biocompatibility for application in the health field with excellent mechanical properties. The blend was obtained by solubilization of polymers in organic solvents. To investigate the polymer thermochemical properties, FTIR and DSC were applied. To investigate the composition's influence over polymer mechanical properties, tensile and hardness test were applied. To analyze the blends response in the cell environment, a stent was produced by injection molding process, and Cell Viability Test and Previous Implantability were used. The Infrared spectra show that chemical composition is related only with polymers proportion in the blend. The calorimetry shows a partial miscibility in the blend. The tensile test shows that adding Poly(Isoprene to Poly(Lactic-co-Glycolic Acid induced a relevant reduction in the Young modulus, tensile stress and tenacity of the material, which was altered from the fragile raw PLGA to a ductile material. The composition did not affect the blend hardness. The cell viability test shows that the blend has potential application as biomaterial, while the first results of implantability indicate that the polymeric stent kept its original position and caused low fibrosis.

Radiation induced crystallinity damage in poly(L-lactic acid)

CERN Document Server

Kantoglu, O

2002-01-01

The radiation-induced crystallinity damage in poly(L-lactic acid) (PLLA) in the presence of air and in vacuum, is studied. From the heat of fusion enthalpy values of gamma irradiated samples, some changes on the thermal properties were determined. To identify these changes, first the glass transition temperature (T sub g) of L-lactic acid polymers irradiated to various doses in air and vacuum have been investigated and it is found that it is independent of irradiation atmosphere and dose. The fraction of damaged units of PLLA per unit of absorbed energy has been measured. For this purpose, SAXS and differential scanning calorimetry methods were used, and the radiation yield of number of damaged units (G(-u)) is found to be 0.74 and 0.58 for PLLA samples irradiated in vacuum and air, respectively.

Establishment of novel meniscal scaffold structures using polyglycolic and poly-l-lactic acids.

Science.gov (United States)

Murakami, Tomohiko; Otsuki, Shuhei; Nakagawa, Kosuke; Okamoto, Yoshinori; Inoue, Tae; Sakamoto, Yuki; Sato, Hideki; Neo, Masashi

2017-08-01

The purpose of this study was to evaluate various types of meniscus scaffolds that mimic the meniscus structure, and to establish a novel cell-free meniscus scaffold with polyglycolic acid or poly-l-lactic acid. Four types of scaffolds were implanted into Japanese white rabbits: poly-l-lactic acid sponge poly-l-lactic acid, PGA-coated PLLA sponge, PGA lamination, and film-coated PGA lamination. Samples were harvested at 8 and 12 weeks after implantation, and a compression stress test was performed. The meniscus size and Ishida scores were evaluated for regenerated tissue. Immunohistochemistry was analyzed by anti-type I, II and X collagen antibodies to investigate the structure of the regenerated tissue, and by anti-iNOS antibody to investigate the inflammatory tissue of the meniscus. The cell nuclei of lymphocytes and foreign body multinucleated giant cells were counted in hematoxylin and eosin staining. Modified Mankin scores for cartilage degeneration were used for assessment after Safranin-O/Fast Green staining. The biomechanical test showed that l- and film-coated PGA lamination exhibited greater strength than s- and PGA-coated PLLA sponge. At 12 weeks, the size of meniscus and the Ishida score in implanted film-coated PGA lamination were improved significantly compared with the defect groups. The type II collagen staining intensity in the PGA lamination lamination is significantly higher than the defect at eight weeks. The staining intensity of iNOS and number of lymphocytes significantly increased in sponge poly-l-lactic acid at eight weeks, and increased in p-PLLA at 12 weeks. Foreign body multinucleated giant cells in implantation groups appeared, especially at eight weeks. The Mankin score for film-coated PGA lamination was significantly lower than for the defect at 12 weeks. Novel meniscal scaffolds especially PGA should possess not only biological but also biomechanical functions. In conclusions, film-coated PGA lamination was the beneficial property

Biodegradability and Biocompatibility Study of Poly(Chitosan-g-lactic Acid Scaffolds

Directory of Open Access Journals (Sweden)

Zhe Zhang

2012-03-01

Full Text Available A biodegradable, biocompatible poly(chitosan-g-lactic acid (PCLA scaffold was prepared and evaluated in vitro and in vivo. The PCLA scaffold was obtained by grafting lactic acid (LA onto the amino groups on chitosan (CS without a catalyst. The PCLA scaffolds were characterized by Fourier Transform infrared spectroscopy (FT-IR and scanning electron microscopy (SEM. The biodegradabilty was determined by mass loss in vitro, and degradation in vivo as a function of feed ratio of LA/CS. Bone marrow mesenchymal stem cell (BMSC culture experiments and histological examination were performed to evaluate the PCLA scaffolds’ biocompatibility. The results indicated that PCLA was promising for tissue engineering application.

Tailoring the morphology and properties of poly(lactic acid)/poly(ethylene-co-vinyl acetate)/starch blends via reactive compatibilization

NARCIS (Netherlands)

Ma, P.; Hristova - Bogaerds, D.G.; Schmit, P.; Goossens, J.G.P.; Lemstra, P.J.

2012-01-01

Poly(lactic acid)/poly(ethylene-co-vinyl acetate)/starch (PLA/EVA/starch) ternary blends were prepared by multi-step melt processing (reactive extrusion) in the presence of maleic anhydride (MA), benzoyl peroxide and glycerol. The effects of MA and glycerol concentration on the morphology and

Phase behaviour of the ternary mixture system of poly(L-lactic acid), dichloromethane and carbon dioxide

International Nuclear Information System (INIS)

Gwon, Jungmin; Cho, Dong Woo; Kim, Soo Hyeon; Shin, Hun Yong; Kim, Hwayong

2012-01-01

Highlights: ► The high pressure phase behaviour of poly(L-lactic acid), dichloromethane and carbon dioxide ternary mixtures was measured. ► The experimental data shows the characteristics of the LCST behaviour of polymer–solvent–gas systems. ► The experimental data correlation was performed using the hybrid EOS. - Abstract: In this study, the high pressure phase behaviour of poly(L-lactic acid) (M = 312,000), dichloromethane and carbon dioxide ternary mixtures was studied using a variable volume view cell at temperatures ranging from 313.15 K to 363.15 K and pressures of up to 30.0 MPa as functions of temperature and the CO 2 /dichloromethane mass ratio at poly(L-lactic acid) weight fractions of 1.0%, 2.5% and 3.0%. The experimental results were correlated with the hybrid equation of state for the CO 2 -polymer system using the van der Waals one-fluid mixing rule with three adjustable binary interaction parameters.

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...

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.

Effect of halloysite nanotubes on the thermal degradation behaviour of poly(.epsilon.-caprolactone)/poly(lactic acid) microfibrillar composites

Czech Academy of Sciences Publication Activity Database

Luyt, A. S.; Kelnar, Ivan

2017-01-01

Roč. 60, July (2017), s. 166-172 ISSN 0142-9418 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:61389013 Keywords : poly(lactic acid) * poly(epsilon-caprolactone) * halloysite nanotubes Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 2.464, year: 2016

Efficacy of Poly(D,L-Lactic Acid-co-Glycolic acid)-Poly(Ethylene Glycol)-Poly(D,L-Lactic Acid-co-Glycolic Acid) Thermogel As a Barrier to Prevent Spinal Epidural Fibrosis in a Postlaminectomy Rat Model.

Science.gov (United States)

Li, Xiangqian; Chen, Lin; Lin, Hong; Cao, Luping; Cheng, Ji'an; Dong, Jian; Yu, Lin; Ding, Jiandong

2017-04-01

Experimental animal study. The authors conducted a study to determine the efficacy and safety of the poly(D,L-lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) thermogel to prevent peridural fibrosis in an adult rat laminectomy model. Peridural fibrosis often occurs after spinal laminectomy. It might cause persistent back and/or leg pain postoperatively and make a reoperation more difficult and dangerous. Various materials have been used to prevent epidural fibrosis, but only limited success has been achieved. The PLGA-PEG-PLGA thermogel was synthesized by us. Total L3 laminectomies were performed on 24 rats. The PLGA-PEG-PLGA thermogel or chitosan (CHS) gel (a positive control group) was applied to the operative sites in a blinded manner. In the control group, the L3 laminectomy was performed and the defect was irrigated with the NS solution 3 times. All the rats were killed 4 weeks after the surgery. The cytotoxicity of this thermogel was evaluated in vitro and the result demonstrated that no evidence of cytotoxicity was observed. The extent of epidural fibrosis, the area of epidural fibrosis, and the density of the fibroblasts and blood vessel were evaluated histologically. There were statistical differences among the PLGA-PEG-PLGA thermogel or CHS gel group compared with the control group. Although there was no difference between the PLGA-PEG-PLGA thermogel and CHS gel, the efficiency of the PLGA-PEG-PLGA thermogel was shown to be slightly improved compared with the CHS gel. The biocompatibility of the PLGA-PEG-PLGA thermogel was proven well. The application of this thermogel effectively reduced epidural scarring and prevented the subsequent adhesion to the dura mater. No side effects were noted in the rats.

Biocompatibility of poly(lactic acid) with incorporated graphene-based materials

OpenAIRE

Pinto, Artur Moreira; Moreira, Susana Margarida Gomes; Gonçalves, Inês; Gama, F. M.; Mendes, Adélio; Magalhães, Fernão D.

2013-01-01

The incorporation of graphene-based materials has been shown to improve mechanical properties of poly(lactic acid) (PLA). In this work, PLA films and composite PLA films incorporating two graphene-based materials – graphene oxide (GO) and graphene nanoplatelets (GNP) – were prepared and characterized regarding not only biocompatibility, but also surface topography, chemistry and wettability. The presence of both fillers changed the films surface topography, increasing the roughness, and modif...

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

International Nuclear Information System (INIS)

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

2013-01-01

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

3D FT-IR imaging spectroscopy of phase-separation in a poly(3-hydroxybutyrate)/poly(L-lactic acid) blend

Science.gov (United States)

Miriam Unger; Julia Sedlmair; Heinz W. Siesler; Carol Hirschmugl; Barbara Illman

2014-01-01

In the present study, 3D FT-IR spectroscopic imaging measurements were applied to study the phase separation of a poly(3-hydroxybutyrate) (PHB)/poly(L-lactic acid) (PLA) (50:50 wt.%) polymer blend film. While in 2D projection imaging the z-dependent information is overlapped, thereby complicating the analysis, FT-IR spectro-micro-tomography,...

[Poly-L-lactic-acid filling of facial lipoatrophy in HIV+ patients under tritherapy].

Science.gov (United States)

Thiéry, G; Coulet, O; Adam, S; Guyot, L

2008-04-01

Facial lipoatrophy is one of the complications of antiretroviral therapy in HIV+ patients. Poly-L-lactic-acid filling can compensate this atrophy. This treatment has been completely covered by social security since 2005. The filling technique is described in this article.

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

Science.gov (United States)

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

2014-01-01

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

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...

Treating Simple Tibia Fractures with Poly-DL-Lactic Acid Screw as a ...

African Journals Online (AJOL)

Purpose: To investigate the curative effect of poly-DL-lactic acid (PDLLA) absorbable screw as a locked intramedullary nail for simple tibia fractures. Methods: In this study, 35 patients treated with the PDLLA screw were observed, and another 35 patients treated with a traditional locking intramedullary nail were treated as ...

Optimization of Preparation Techniques for Poly(Lactic Acid-Co-Glycolic Acid) Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Birnbaum, Duane T.; Kosmala, Jacqueline D.; Brannon-Peppas, Lisa [Biogel Technology, Inc. (United States)], E-mail: lisabp@biogeltech.com

2000-06-15

Microparticles and nanoparticles of poly(lactic acid-co-glycolic acid) (PLAGA) are excellent candidates for the controlled release of many pharmaceutical compounds because of their biodegradable nature. The preparation of submicron PLAGA particles poses serious challenges that are not necessarily present when preparing microparticles. We have evaluated several combinations of organic solvents and surfactants used in the formulation of PLAGA nanoparticles. Critical factors such as the ability to separate the nanoparticles from the surfactant, the ability to re-suspend the nanoparticles after freeze-drying, formulation yield and nanoparticle size were studied. The smallest particles were obtained using the surfactant/solvent combination of sodium dodecyl sulfate and ethyl acetate (65 nm) and the largest particles were obtained using poly(vinyl alcohol) and dichloromethane (466 nm). However, the optimal nanoparticles were produced using either acetone or ethyl acetate as the organic solvent and poly(vinyl alcohol) or human serum albumin as the surfactant. This is because the most critical measure of performance of these nanoparticles proved to be their ability to re-suspend after freeze-drying.

Optimization of Preparation Techniques for Poly(Lactic Acid-Co-Glycolic Acid) Nanoparticles

International Nuclear Information System (INIS)

Birnbaum, Duane T.; Kosmala, Jacqueline D.; Brannon-Peppas, Lisa

2000-01-01

Microparticles and nanoparticles of poly(lactic acid-co-glycolic acid) (PLAGA) are excellent candidates for the controlled release of many pharmaceutical compounds because of their biodegradable nature. The preparation of submicron PLAGA particles poses serious challenges that are not necessarily present when preparing microparticles. We have evaluated several combinations of organic solvents and surfactants used in the formulation of PLAGA nanoparticles. Critical factors such as the ability to separate the nanoparticles from the surfactant, the ability to re-suspend the nanoparticles after freeze-drying, formulation yield and nanoparticle size were studied. The smallest particles were obtained using the surfactant/solvent combination of sodium dodecyl sulfate and ethyl acetate (65 nm) and the largest particles were obtained using poly(vinyl alcohol) and dichloromethane (466 nm). However, the optimal nanoparticles were produced using either acetone or ethyl acetate as the organic solvent and poly(vinyl alcohol) or human serum albumin as the surfactant. This is because the most critical measure of performance of these nanoparticles proved to be their ability to re-suspend after freeze-drying

Optimization of Preparation Techniques for Poly(Lactic Acid-Co-Glycolic Acid) Nanoparticles

Science.gov (United States)

Birnbaum, Duane T.; Kosmala, Jacqueline D.; Brannon-Peppas, Lisa

2000-06-01

Microparticles and nanoparticles of poly(lactic acid-co-glycolic acid) (PLAGA) are excellent candidates for the controlled release of many pharmaceutical compounds because of their biodegradable nature. The preparation of submicron PLAGA particles poses serious challenges that are not necessarily present when preparing microparticles. We have evaluated several combinations of organic solvents and surfactants used in the formulation of PLAGA nanoparticles. Critical factors such as the ability to separate the nanoparticles from the surfactant, the ability to re-suspend the nanoparticles after freeze-drying, formulation yield and nanoparticle size were studied. The smallest particles were obtained using the surfactant/solvent combination of sodium dodecyl sulfate and ethyl acetate (65 nm) and the largest particles were obtained using poly(vinyl alcohol) and dichloromethane (466 nm). However, the optimal nanoparticles were produced using either acetone or ethyl acetate as the organic solvent and poly(vinyl alcohol) or human serum albumin as the surfactant. This is because the most critical measure of performance of these nanoparticles proved to be their ability to re-suspend after freeze-drying.

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.

Development of new force sensor using super-multilayer alternating laminated film comprising piezoelectric poly(l-lactic acid) and poly(d-lactic acid) films in the shape of a rectangle with round corners

Science.gov (United States)

Tajitsu, Yoshiro; Adachi, Yu; Nakatsuji, Takahiro; Tamura, Masataka; Sakamoto, Kousei; Tone, Takaaki; Imoto, Kenji; Kato, Atsuko; Yoshida, Testuo

2017-10-01

A new super-multilayer alternating laminated film in the shape of a rectangle with round corners has been developed. The super-multilayer film, which comprised piezoelectric poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) films, was wound with the number of turns on the order of from 100 to 1000 to form piezoelectric rolls. These piezoelectric rolls could generate an induced voltage of more than 95% of the initial voltage for over 10 s when a constant load was applied. The desired duration and magnitude of the piezoelectric response voltage were realized by adjusting the number of turns of the piezoelectric rolls. Similarly to many other conventional piezoelectrics, the piezoelectric rolls enable instantaneous load-dependent voltage generation and attenuation. The piezoelectric rolls are also lighter than conventional piezoelectric ceramics and can be used as a novel pressure sensor.

Facial volumetric correction with injectable poly-L-lactic acid.

Science.gov (United States)

Vleggaar, Danny

2005-11-01

Polymers of lactic acid'have been widely used for many years in different types of medical devices, such as resorbable sutures, intrabone implants, and soft tissue implants. Injectable poly-L-lactic acid (PLLA; Sculptra), a synthetic, biodegradable polymer, has gained widespread popularity in Europe for the treatment of facial changes associated with aging. To provide background information on injectable PLLA and to describe clinical experience with its use in Europe for facial volume enhancement. Technique varies with site of injection. Generally, the product is implanted subcutaneously or intradermally in a series of treatments. No allergy testing is required. Based on experience in more than 2,500 patients, injectable PLLA has been used successfully for the correction of nasolabial folds, mid- and lower facial volume loss, jawline laxity, and other signs of facial aging. Correction lasts for 18 to 24 months in most patients. Injectable PLLA treatment provides an excellent and prolonged correction of a variety of facial wrinkles, depressions, and laxity with a minimally invasive procedure that does not require allergy testing or a recovery period.

Lignin-coated cellulose nanocrystals as promising nucleating agent for poly(lactic acid)

Science.gov (United States)

Anju Gupta; William Simmons; Gregory T. Schueneman; Eric A. Mintz

2016-01-01

We report the effect of lignin-coated cellulose nanocrystals (L-CNCs) on the crystallization behavior of poly(lactic acid) (PLA). PLA/L-CNC nanocomposites were prepared by melt mixing, and the crystallization behavior of PLA was investigated using differential scanning calorimetry. Isothermal crystallization data were analyzed using Avrami and Lauritzen–Hoffman...

Plasticized Biodegradable Poly(lactic acid) Based Composites Containing Cellulose in Micro- and Nanosize

OpenAIRE

Halász, Katalin; Csóka, Levente

2013-01-01

The aim of this work was to study the characteristics of thermal processed poly(lactic acid) composites. Poly(ethylene glycol) (PEG400), microcrystalline cellulose (MCC), and ultrasound-treated microcrystalline cellulose (USMCC) were used in 1, 3, and 5 weight percents to modify the attributes of PLA matrix. The composite films were produced by twin screw extrusion followed by film extrusion. The manufactured PLA-based films were characterized by tensile testing, differential scanning calorim...

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

International Nuclear Information System (INIS)

Souza, D.H.S.; Dias, M.L.

2010-01-01

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)

Fracture behavior of highly toughened poly(lactic acid)/ethylene-co-vinyl acetate blends

NARCIS (Netherlands)

Zeng, Q.; Feng, Y.; Wang, R.; Ma, P.

2018-01-01

Poly(lactic acid) (PLA) is brittle which restricts the range of its applications. The toughness of PLA was effectively improved in this work by incorporation of rubber grade ethylene-co-vinyl acetate (EVM). For example, the elongation at break of PLA increased by about 50 times after the addition of

Oriented gold ripple-like structures on poly-L-lactic acid

Energy Technology Data Exchange (ETDEWEB)

Juřík, Petr, E-mail: petr.jurik@gmail.com [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic); Slepička, Petr [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic); Mistrík, Jan; Janíček, Petr [Department of Applied Physics and Mathematics, University of Pardubice (Czech Republic); Rimpelová, Silvie [Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague (Czech Republic); Kolská, Zdeňka [Faculty of Science, University of J. E. Purkyně, Ústí nad Labem (Czech Republic); Švorčík, Václav [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic)

2014-12-01

Highlights: • We prepared oriented ripple-like structures on polymer surface with thin gold layer. • These structures show preferential orientation over large areas which is unusual for heat induced wrinkling. • Significant electrical and optical anisotropy was observed. • Zeta-potential, XPS, goniometry and ellipsometry suggest formation of gold lines separated by polymer gaps. • Increase in cell growth in comparison with poly-styrene mock was observed. - Abstract: In this paper chemical, morphological, electrical and biological properties of poly-L-lactic acid thin films with gold nanolayers were studied. These samples were examined as-sputtered and annealed at glass transition temperature. Morphological changes of poly-L-lactic films introduced by annealing were studied by means of atomic force microscopy. This method showed formation of oriented ripple-like structures on the surface of the film. X-ray photoelectron spectroscopy, goniometry, ellipsometry, sheet resistance measurement and electrokinetic analysis were used to determine distribution of gold on the surface. Combined data suggests that these ripple-like structures were formed by gold lines with insulating polymer gaps in between. These lines show preferential orientation over large areas and under proper conditions offer simple way to form electrically anisotropic material on large scale. Also cytocompatibility was studied showing increased cell adhesion and proliferation of mouse embryonic fibroblasts offering another use for these easily formed structures.

Oriented gold ripple-like structures on poly-L-lactic acid

International Nuclear Information System (INIS)

Juřík, Petr; Slepička, Petr; Mistrík, Jan; Janíček, Petr; Rimpelová, Silvie; Kolská, Zdeňka; Švorčík, Václav

2014-01-01

Highlights: • We prepared oriented ripple-like structures on polymer surface with thin gold layer. • These structures show preferential orientation over large areas which is unusual for heat induced wrinkling. • Significant electrical and optical anisotropy was observed. • Zeta-potential, XPS, goniometry and ellipsometry suggest formation of gold lines separated by polymer gaps. • Increase in cell growth in comparison with poly-styrene mock was observed. - Abstract: In this paper chemical, morphological, electrical and biological properties of poly-L-lactic acid thin films with gold nanolayers were studied. These samples were examined as-sputtered and annealed at glass transition temperature. Morphological changes of poly-L-lactic films introduced by annealing were studied by means of atomic force microscopy. This method showed formation of oriented ripple-like structures on the surface of the film. X-ray photoelectron spectroscopy, goniometry, ellipsometry, sheet resistance measurement and electrokinetic analysis were used to determine distribution of gold on the surface. Combined data suggests that these ripple-like structures were formed by gold lines with insulating polymer gaps in between. These lines show preferential orientation over large areas and under proper conditions offer simple way to form electrically anisotropic material on large scale. Also cytocompatibility was studied showing increased cell adhesion and proliferation of mouse embryonic fibroblasts offering another use for these easily formed structures

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.

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

International Nuclear Information System (INIS)

Zhao Hong; Saatchi, Katayoun; Haefeli, Urs O.

2009-01-01

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.

Combination of Poly(lactic) Acid and Starch for Biodegradable Food Packaging

OpenAIRE

Muller, Justine; Gonz?lez-Mart?nez, Chelo; Chiralt, Amparo

2017-01-01

The massive use of synthetic plastics, in particular in the food packaging area, has a great environmental impact, and alternative more ecologic materials are being required. Poly(lactic) acid (PLA) and starch have been extensively studied as potential replacements for non-degradable petrochemical polymers on the basis of their availability, adequate food contact properties and competitive cost. Nevertheless, both polymers exhibit some drawbacks for packaging uses and need to be adapted to th...

Poly(Lactic Acid) Filled with Cassava Starch-g-Soybean Oil Maleate

OpenAIRE

Kiangkitiwan, Nopparut; Srikulkit, Kawee

2013-01-01

Poly(lactic acid), PLA, is a biodegradable polymer, but its applications are limited by its high cost and relatively poorer properties when compared to petroleum-based plastics. The addition of starch powder into PLA is one of the most promising efforts because starch is an abundant and cheap biopolymer. However, the challenge is the major problem associated with poor interfacial adhesion between the hydrophilic starch granules and the hydrophobic PLA, leading to poorer mechanical properties....

Poly(lactic acid) (PLA) Based Tear Resistant and Biodegradable Flexible Films by Blown Film Extrusion

OpenAIRE

Norma Mallegni; Thanh Vu Phuong; Maria-Beatrice Coltelli; Patrizia Cinelli; Andrea Lazzeri

2018-01-01

Poly(lactic acid) (PLA) was melt mixed in a laboratory extruder with poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS) in the presence of polypropylene glycol di glycidyl ether (EJ400) that acted as both plasticizer and compatibilizer. The process was then scaled up in a semi-industrial extruder preparing pellets having different content of a nucleating agent (LAK). All of the formulations could be processed by blowing extrusion and the obtained films showed me...

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 (epsilon-caprolactone) * poly (lactic acid) * microfibrillar composites Subject RIV: JI - Composite Materials Impact factor: 3.108, year: 2016

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.

Multiscale Modeling of Poly(lactic acid) Production: From Reaction Conditions to Rheology of Polymer Melt

DEFF Research Database (Denmark)

Zubov, Alexandr; Sin, Gürkan

2018-01-01

Abstract Poly(L-lactic acid) (PLLA) is a fully biodegradable bioplastic with promising market potential. The paper deals with systematic development and analysis of the modeling framework allowing direct mapping between PLLA production process conditions and rheological properties of the polymer ...

NANOCOMPOSITES OF POLY(LACTIC ACID REINFORCED WITH CELLULOSE NANOFIBRILS

Directory of Open Access Journals (Sweden)

Liping Zhang

2010-06-01

Full Text Available A chemo-mechanical method was used to prepare cellulose nanofibrils dispersed uniformly in an organic solvent. Poly(ethylene glycol (PEG 1000 was added to the matrix as a compatibilizer to improve the interfacial interaction between the hydrophobic poly(lactic acid (PLA and the hydrophilic cellulose nanofibrils. The composites obtained by solvent casting methods from N,N-Dimethylacetamide (DMAc were characterized by tensile testing machine, atomic force microscope (AFM, scanning electron microscope (SEM, and Fourier transform infrared spectroscopy (FT-IR. The tensile test results indicated that, by adding PEG to the PLA and the cellulose nanofibrils matrix, the tensile strength and the elongation rate increased by 56.7% and 60%, respectively, compared with the PLA/cellulose nanofibrils composites. The FT-IR analysis successfully showed that PEG improved the intermolecular interaction, which is based on the existence of inter-molecular hydrogen bonding among PLA, PEG, and cellulose nanofibrils.

Safety and complications of absorbable threads made of poly-L-lactic acid and poly lactide/glycolide: Experience with 148 consecutive patients.

Science.gov (United States)

Sarigul Guduk, Sukran; Karaca, Nezih

2018-04-01

Thread lifting is a minimally invasive procedure for lifting and repositioning tissues. Few articles with absorbable sutures exist in the literature. Furthermore there is no study focusing on complications of absorbable sutures. To describe complications of thread lifting using a totally absorbable suture composed of poly-L-lactic acid affixed with poly lactide/glycolide cones. Data regarding complications were analyzed retrospectively for 148 patients underwent thread lifting between June 2014 and February 2017. A total of 321 pairs of sutures used in the 148 patients studied. Overall 40 (27%) patients had complications regarded as minimal or moderate without permanent sequela. The most common complication was skin dimpling and irregularity (n = 17, 11.4%) followed by ecchymosis (n = 12, 8.1%), suture extrusion (n = 4, 2.7%), and pain (n = 4, 2.7%) Except one patient, dimpling, and irregularity resolved in all patients after 3-7 days spontaneously. Suture migration was observed in 2 (1.35%) patients. Hematoma and infection were seen in 2 patients one for each. The procedure using sutures made of absorbable poly-L-lactic acid and poly lactide/glycolide is a relatively safe procedure without major complications. © 2018 Wiley Periodicals, Inc.

Effect of Zinc Oxide Addition on Antibacterial Behavior of Hydroxyapatite-Poly lactic-co-glycolic acid Scaffold for Bone Tissue Engineering Applications

Directory of Open Access Journals (Sweden)

Narges Abotalebi

2018-03-01

Full Text Available Introduction: Infection after the surgery is one of the problems of bone scaffolds implants which is normally treated by systemic administration of antibiotics. But due to the poor blood circulation in bone tissue, large antibiotic doses are needed which lead to further drawbacks to renal and hepatic systems. Material and method: In this study, the effect of zinc oxide addition on antibacterial behavior of hydroxyapatite- Poly lactic-co-glycolic acid scaffold was evaluated. The synthesized composite was characterized by X-ray diffraction, scanning electron microscopy equipped with elemental analysis and Fourier transform infrared spectra. In order to determine the antibacterial activity of the fabricated scaffold, Staphylococcus aureus (ATTC 25922 and Escherichia coli (ATTC 25923 were used as test microorganisms. Results: The results showed that Hydroxyapatite- Poly lactic-co-glycolic acid scaffold did not make inhibition zone in culture medium but the modification of Hydroxyapatite- Poly lactic-co-glycolic acid scaffold’s surface by zinc oxide particles caused Hydroxyapatite- Poly lactic-co-glycolic acid- zinc oxide scaffold to have antibacterial inhibition zone of 12 and 20 mm for Escherichia coli and Staphylococcus aureus, respectively. Discussion and conclusion: This study revealed that the addition of antibacterial agent to applicable bone tissue engineering scaffolds could be considered as an appropriate way to prevent the growth of infection at the scaffold site.

Plasticized Biodegradable Poly(lactic acid Based Composites Containing Cellulose in Micro- and Nanosize

Directory of Open Access Journals (Sweden)

Katalin Halász

2013-01-01

Full Text Available The aim of this work was to study the characteristics of thermal processed poly(lactic acid composites. Poly(ethylene glycol (PEG400, microcrystalline cellulose (MCC, and ultrasound-treated microcrystalline cellulose (USMCC were used in 1, 3, and 5 weight percents to modify the attributes of PLA matrix. The composite films were produced by twin screw extrusion followed by film extrusion. The manufactured PLA-based films were characterized by tensile testing, differential scanning calorimetry (DSC, scanning electron microscopy (SEM, wide angle X-ray diffraction (WAXD, and degradation test.

Ibuprofen-loaded poly(lactic-co-glycolic acid films for controlled drug release

Directory of Open Access Journals (Sweden)

Pang JM

2011-04-01

Full Text Available Jianmei Pang1, Yuxia Luan1, Feifei Li1, Xiaoqing Cai1, Jimin Du2, Zhonghao Li31School of Pharmaceutical Science, Shandong University, Jinan, Shandong Province, PR China; 2School of Chemistry and Chemical Engineering, Anyang Normal University, Henan Province, PR China; 3School of Materials Science and Engineering, Shandong University, Jinan, Shandong Province, PR ChinaAbstract: Ibuprofen- (IBU loaded biocompatible poly(lactic-co-glycolic acid (PLGA films were prepared by spreading polymer/ibuprofen solution on the nonsolvent surface. By controlling the weight ratio of drug and polymer, different drug loading polymer films can be obtained. The synthesized ibuprofen-loaded PLGA films were characterized with scanning electron microscopy, powder X-ray diffraction, and differential scanning calorimetry. The drug release behavior of the as-prepared IBU-loaded PLGA films was studied to reveal their potential application in drug delivery systems. The results show the feasibility of the as-obtained films for controlling drug release. Furthermore, the drug release rate of the film could be controlled by the drug loading content and the release medium. The development of a biodegradable ibuprofen system, based on films, should be of great interest in drug delivery systems.Keywords: ibuprofen, controlled release, poly(lactic-co-glycolic acid, films

Influence of the addition of bentonite clay in poli (butylene adipate co-terephthalic) / poly(lactic acid) membranes

International Nuclear Information System (INIS)

Morais, D.D.S.; Medeiros, K.M.; Araujo, E.M.; Melo, T.J.A.; Barbosa, R.

2014-01-01

The processes of membrane separation have been used in many different sectors of industrial activity, ranging from the chemical industry, food, pharmaceutical, medical and biotech. In this paper, a bentonite clay was added by melt intercalation in a poly(butylene adipate-co-terephthalic acid)/poly(lactic acid) blend at levels 1 and 3 wt% of clay. After that, membranes were produced by solvent evaporation technique. From the XRD results, it was verified the possible formation of exfoliated/partially exfoliated structures in the membranes. By DSC, it was observed that the addition of clay did not promote alterations in glass transition temperature and crystalline melting of the PBAT/PLA matrix. The morphology of the membranes were observed by SEM and it was verified the clay formation of porous membranes. (author)

Biotechnological Production of Lactic Acid and Its Recent Applications

Directory of Open Access Journals (Sweden)

Young-Jung Wee

2006-01-01

Full Text Available Lactic acid is widely used in the food, cosmetic, pharmaceutical, and chemical industries and has received increased attention for use as a monomer for the production of biodegradable poly(lactic acid. It can be produced by either biotechnological fermentation or chemical synthesis, but the former route has received considerable interest recently, due to environmental concerns and the limited nature of petrochemical feedstocks. There have been various attempts to produce lactic acid efficiently from inexpensive raw materials. We present a review of lactic acid-producing microorganisms, raw materials for lactic acid production, fermentation approaches for lactic acid production, and various applications of lactic acid, with a particular focus on recent investigations. In addition, the future potentials and economic impacts of lactic acid are discussed.

Effect of homopolymer poly(vinyl acetate on compatibility and mechanical properties of poly(propylene carbonate/poly(lactic acid blends

Directory of Open Access Journals (Sweden)

J. Gao

2012-11-01

Full Text Available A small amount of homopolymer poly(vinyl acetate (PVAc is used to compatibilize the biodegradable blends of poly(propylene carbonate (PPC and poly(lactic acid (PLA. Scanning electron microscopy (SEM and differential scanning calorimetry (DSC results show that PVAc is selectively localized in the PLA phase and at the interface between PPC and PLA phases. As a result, these interface-localized PVAc layers act as not only a compatibilizer to improve the phase dispersion significantly but also a bridge to increase the interfacial adhesion between PPC and PLA phases dramatically. Both of them are believed to be responsible for the enhancement in mechanical properties. This work provides a simple avenue to fabricate eco-friendly PPC/PLA blends with high performance, and in some cases, reducing the demand for petroleumbased plastics such as polypropylene.

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: 1.371, year: 2015

Surface changes of poly-L-lactic acid due to annealing

Science.gov (United States)

Juřík, P.; Michaljaničová, I.; Slepička, P.; Kolskáa, Z.; Švorčík, V.

2017-11-01

Surface modifications are very important part of both current cutting-edge research and modern manufacturing. Our research is focused on poly-L-lactic acid, which is biocompatible and biodegradable polymer that offers applications in modern medicine. We observed morphological changes of the surface of metalized samples due to annealing and studied effect of modifications on total surface area and pore surface and volume. We observed that annealing of non-metalized samples had most pronounced effect up to the 70°C, after which all observed parameters dropped significantly. Metallization has changed behaviour of the samples significantly and resulted in generally lower surface area and porosity when compared to non-metalized samples.

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.

New Poly(lactic acid) Active Packaging Composite Films Incorporated with Fungal Melanin

OpenAIRE

Łukasz Łopusiewicz; Filip Jędra; Małgorzata Mizielińska

2018-01-01

In this work, fungal melanin was used for the first time to prepare poly(lactic acid)-based composites. The films of various melanin concentrations (0.025%, 0.05% and 0.2% w/w) were prepared using an extrusion method. The mechanical, antioxidant, antimicrobial, water vapor and UV-Vis barrier properties, as well as available polyphenolics on the surface, were studied. FT-IR and Raman spectroscopy studies were carried out to analyze the chemical composition of the resulting films. The hydrophob...

Effect of the Talc Filler on Structural, Water Vapor Barrier and Mechanical Properties of Poly(lactic acid) Composites.

Czech Academy of Sciences Publication Activity Database

Buzarovska, A.; Bogoeva-Gaceva, G.; Fajgar, Radek

2016-01-01

Roč. 36, č. 2 (2016), s. 181-188 ISSN 0334-6447 Institutional support: RVO:67985858 Keywords : composites * packaging * poly (lactic acid) Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.658, year: 2016

D-Lactic acid biosynthesis from biomass-derived sugars via Lactobacillus delbrueckii fermentation.

Science.gov (United States)

Zhang, Yixing; Vadlani, Praveen V

2013-12-01

Poly-lactic acid (PLA) derived from renewable resources is considered to be a good substitute for petroleum-based plastics. The number of poly L-lactic acid applications is increased by the introduction of a stereocomplex PLA, which consists of both poly-L and D-lactic acid and has a higher melting temperature. To date, several studies have explored the production of L-lactic acid, but information on biosynthesis of D-lactic acid is limited. Pulp and corn stover are abundant, renewable lignocellulosic materials that can be hydrolyzed to sugars and used in biosynthesis of D-lactic acid. In our study, saccharification of pulp and corn stover was done by cellulase CTec2 and sugars generated from hydrolysis were converted to D-lactic acid by a homofermentative strain, L. delbrueckii, through a sequential hydrolysis and fermentation process (SHF) and a simultaneous saccharification and fermentation process (SSF). 36.3 g L(-1) of D-lactic acid with 99.8 % optical purity was obtained in the batch fermentation of pulp and attained highest yield and productivity of 0.83 g g(-1) and 1.01 g L(-1) h(-1), respectively. Luedeking-Piret model described the mixed growth-associated production of D-lactic acid with a maximum specific growth rate 0.2 h(-1) and product formation rate 0.026 h(-1), obtained for this strain. The efficient synthesis of D-lactic acid having high optical purity and melting point will lead to unique stereocomplex PLA with innovative applications in polymer industry.

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

Science.gov (United States)

Yanagisawa, Mitsunori; Nakamura, Kanami; Nakasaki, Kiyohiko

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

Improved cellular response of ion modified poly(lactic acid-co-glycolic acid) substrates for mouse fibroblast cells

International Nuclear Information System (INIS)

Adhikari, Ananta Raj; Geranpayeh, Tanya; Chu, Wei Kan; Otteson, Deborah C.

2016-01-01

In this report, the effects of argon (Ar) ion irradiation on poly(lactic acid-co-glycolic acid) (PLGA) substrates on biocompatibility were studied. PLGA scaffold substrates were prepared by spin coating glass surfaces with PLGA dissolved in anhydrous chloroform. Previously, we showed that surface modifications of PLGA films using ion irradiation modulate the inherent hydrophobicity of PLGA surface. Here we show that with increasing ion dose (1 × 10 12 to 1 × 10 14 ions/cm 2 ), hydrophobicity and surface roughness decreased. Biocompatibility for NIH3T3 mouse fibroblast cells was increased by argon irradiation of PLGA substrates. On unirradiated PLGA films, fibroblasts had a longer doubling time and cell densities were 52% lower than controls after 48 h in vitro. Argon irradiated PLGA substrates supported growth rates similar to control. Despite differences in cell cycle kinetics, there was no detectible cytotoxicity observed on any substrate. This demonstrates that argon ion irradiation can be used to tune the surface microstructure and generate substrates that are more compatible for the cell growth and proliferation. - Highlights: • Argon irradiation modifies surface chemistry and increases hydrophilicity of poly(lactic-glycolic) acid (PLGA) films. • Both native and irradiated PLGA films were not cytotoxic for mouse fibroblasts. • Fibroblast proliferation increased on PLGA substrates modified with higher doses of Argon irradiation. • Surface modification with Argon irradiation increases biocompatibility of PLGA films.

Thermal properties of extruded injection-molded poly (lactic acid) and milkweed composites: degradation kinetics and enthalpic relaxation

Science.gov (United States)

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

Temperature dependence of poly(lactic acid) mechanical properties

DEFF Research Database (Denmark)

Zhou, Chengbo; Guo, Huilong; Li, Jingqing

2016-01-01

The mechanical properties of polymers are not only determined by their structures, but also related to the temperature field in which they are located. The yield behaviors, Young's modulus and structures of injection-molded poly(lactic acid) (PLA) samples after annealing at different temperatures....... The crystallinity increases with increasing annealing temperature and a' form crystal is formed when the annealing temperature is higher than 100 oC. The stretched samples with low crystallinity show the first yield at draw temperatures below the glass transition temperature (Tg) and the second yield above Tg....... For the samples annealed between 80 and 120 oC, a peculiar double yield appears when stretched within 50–60 oC and only the first or the second yield can be found at the lower and higher draw temperatures. The yield strain and yield stress together with Young's modulus were obtained and discussed in terms...

Poly(lactic-co-glycolic) acid drug delivery systems through transdermal pathway: an overview

OpenAIRE

Naves, Lucas; Dhand, Chetna; Almeida, Luis; Rajamani, Lakshminarayanan; Ramakrishna, Seeram; Soares, Gra?a

2017-01-01

In past few decades, scientists have made tremendous advancement in the field of drug delivery systems (DDS), through transdermal pathway, as the skin represents a ready and large surface area for delivering drugs. Efforts are in progress to design efficient transdermal DDS that support sustained drug release at the targeted area for longer duration in the recommended therapeutic window without producing side-effects. Poly(lactic-co-glycolic acid) (PLGA) is one of the most promising Food and ...

Effects of substitute coated with hyaluronic acid or poly-lactic acid on implant fixation. Experimental study in ovariectomized and glucocorticoid treated sheep

DEFF Research Database (Denmark)

Andreasen, Christina M; Ding, Ming; Andersen, Thomas L

2018-01-01

Investigated in healthy animal models, hyaluronic acid (HyA) and poly-D,L -lactic acid (PDLLA) demonstrate osteoconductive properties when coated onto hydroxyapatite (HA) and β-tricalcium phosphate (βTCP) scaffolds. In this study, we examined the efficacy of HA/βTCP granules coated with HyA or PD...... formation, HyA and PDDLA are indeed considered valuable as new coating materials for composite ceramics when tested in a sheep model - even in bones of a compromised quality.......Investigated in healthy animal models, hyaluronic acid (HyA) and poly-D,L -lactic acid (PDLLA) demonstrate osteoconductive properties when coated onto hydroxyapatite (HA) and β-tricalcium phosphate (βTCP) scaffolds. In this study, we examined the efficacy of HA/βTCP granules coated with Hy...... allograft obtained from a healthy donor sheep (control), pure HA/βTCP, HA/βTCP-HyA or HA/βTCP-PDLLA. After 12 weeks, the bone formation adjacent to the implant surface was evaluated by histology and histomorphometry, while the implant fixation was measured by a push-out test. The investigation showed a bone...

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...

Thermal Properties of Extruded Injection-Molded Poly (lactic acid) and Milkweed Composites: Degradation Kinectics and Enthalpic Relaxation

Science.gov (United States)

In order to determine the degree of compatibility between Poly (lactic Acid) (PLA) and different biomaterials, PLA was compounded with milkweed fiber, a new crop oil seed. After oil extraction, the remaining cake retained approximately 10% residual oil and 47% protein. The pressed seed cake (10% mo...

Effects of time of heatsetting on the tensile properties of ingeo (tm) poly (lactic acid) (PLA) fabric

Energy Technology Data Exchange (ETDEWEB)

Idumah, C.I. [School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom); Nwachukwu, A.N. [Williamson Research Centre for Molecular Environmental Sciences, School of Earth, Atmospheric and Environmental Science, University of Manchester, M13 9P (United Kingdom)

2013-07-01

Poly (lactic acid) is biodegradable and environmentally benign aliphatic polyester produced from the fermentation of naturally occurring and renewable resources like corn, sugar and vegetables and subsequently converted to a textile fiber through melt spinning and spun bonding. A study of the effect of time of heatsetting on tensile properties of knitted Ingeo (tm) Poly (lactic acid) fabric was investigated and reported in this paper. PLA samples were subjected to increasing heatsetting times of 15s, 30s, 40s, 60s, 90s and 240s at 1300 C using the Werner Mathis Infra red heatsetting equipment. Tensile properties were evaluated using the KES-FB (KAWABATA) fabric evaluation system. The tensile properties determined in weft and warp directions included fabric extension [%], linearity of load extension [-], tensile energy [WT] g.cm/cm2 and tensile resilience [%]. Results revealed the optimum time of heatsetting PLA yarns to attain dimensional stability was within the time range of 30-45s at heatsetting temperature of 130 0C.

Modification of cellulose nanocrystals (CNCs) for use in poly(lactic acid) (PLA)-CNC composite packaging products

Science.gov (United States)

Liqing Wei; Nicole M. Stark; Ronald C. Sabo; Laurent Matuana

2016-01-01

There is growing interest in developing bio-based materials for packaging. Bio-derived materials such as cellulose nanocrystals (CNCs) and poly(lactic acid) (PLA) can be used to develop sustainable packaging applications. Incorporating CNCs into PLA can increase the crystallinity and barrier properties of PLA. The challenge lies in both increasing the flexibility of...

Improved cellular response of ion modified poly(lactic acid-co-glycolic acid) substrates for mouse fibroblast cells

Energy Technology Data Exchange (ETDEWEB)

Adhikari, Ananta Raj, E-mail: aa8381@gmail.com [Department of Sciences, Wentworth Institute of Technology, Boston MA 02115 (United States); Geranpayeh, Tanya [Department of Biology and Biochemistry, University of Houston, Houston, TX 77204 (United States); Chu, Wei Kan [Texas Center for Superconductivity, University of Houston, Houston, TX 77204 (United States); Department of Physics, University of Houston, Houston, TX 77204 (United States); Otteson, Deborah C. [Department of Biology and Biochemistry, University of Houston, Houston, TX 77204 (United States); Department of Basic and Vision Sciences, College of Optometry, University of Houston, Houston, TX 77204 (United States)

2016-03-01

In this report, the effects of argon (Ar) ion irradiation on poly(lactic acid-co-glycolic acid) (PLGA) substrates on biocompatibility were studied. PLGA scaffold substrates were prepared by spin coating glass surfaces with PLGA dissolved in anhydrous chloroform. Previously, we showed that surface modifications of PLGA films using ion irradiation modulate the inherent hydrophobicity of PLGA surface. Here we show that with increasing ion dose (1 × 10{sup 12} to 1 × 10{sup 14} ions/cm{sup 2}), hydrophobicity and surface roughness decreased. Biocompatibility for NIH3T3 mouse fibroblast cells was increased by argon irradiation of PLGA substrates. On unirradiated PLGA films, fibroblasts had a longer doubling time and cell densities were 52% lower than controls after 48 h in vitro. Argon irradiated PLGA substrates supported growth rates similar to control. Despite differences in cell cycle kinetics, there was no detectible cytotoxicity observed on any substrate. This demonstrates that argon ion irradiation can be used to tune the surface microstructure and generate substrates that are more compatible for the cell growth and proliferation. - Highlights: • Argon irradiation modifies surface chemistry and increases hydrophilicity of poly(lactic-glycolic) acid (PLGA) films. • Both native and irradiated PLGA films were not cytotoxic for mouse fibroblasts. • Fibroblast proliferation increased on PLGA substrates modified with higher doses of Argon irradiation. • Surface modification with Argon irradiation increases biocompatibility of PLGA films.

Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles.

Science.gov (United States)

Kamtsikakis, Aristotelis; Kavetsou, Eleni; Chronaki, Konstantina; Kiosidou, Evangelia; Pavlatou, Evangelia; Karana, Alexandra; Papaspyrides, Constantine; Detsi, Anastasia; Karantonis, Antonis; Vouyiouka, Stamatina

2017-09-26

The scope of the current research was to assess the feasibility of encapsulating three commercial antifouling compounds, Irgarol 1051, Econea and Zinc pyrithione, in biodegradable poly(lactic acid) (PLA) nanoparticles. The emulsification-solvent evaporation technique was herein utilized to manufacture nanoparticles with a biocide:polymer ratio of 40%. The loaded nanoparticles were analyzed for their size and size distribution, zeta potential, encapsulation efficiency and thermal properties, while the relevant physicochemical characteristics were correlated to biocide-polymer system. In addition, the encapsulation process was scaled up and the prepared nanoparticles were dispersed in a water-based antifouling paint in order to examine the viability of incorporating nanoparticles in such coatings. Metallic specimens were coated with the nanoparticles-containing paint and examined regarding surface morphology.

Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles

Science.gov (United States)

Kamtsikakis, Aristotelis; Kavetsou, Eleni; Chronaki, Konstantina; Kiosidou, Evangelia; Pavlatou, Evangelia; Karana, Alexandra; Papaspyrides, Constantine; Detsi, Anastasia; Karantonis, Antonis; Vouyiouka, Stamatina

2017-01-01

The scope of the current research was to assess the feasibility of encapsulating three commercial antifouling compounds, Irgarol 1051, Econea and Zinc pyrithione, in biodegradable poly(lactic acid) (PLA) nanoparticles. The emulsification–solvent evaporation technique was herein utilized to manufacture nanoparticles with a biocide:polymer ratio of 40%. The loaded nanoparticles were analyzed for their size and size distribution, zeta potential, encapsulation efficiency and thermal properties, while the relevant physicochemical characteristics were correlated to biocide–polymer system. In addition, the encapsulation process was scaled up and the prepared nanoparticles were dispersed in a water-based antifouling paint in order to examine the viability of incorporating nanoparticles in such coatings. Metallic specimens were coated with the nanoparticles-containing paint and examined regarding surface morphology. PMID:28952560

New Poly(lactic acid Active Packaging Composite Films Incorporated with Fungal Melanin

Directory of Open Access Journals (Sweden)

Łukasz Łopusiewicz

2018-04-01

Full Text Available In this work, fungal melanin was used for the first time to prepare poly(lactic acid-based composites. The films of various melanin concentrations (0.025%, 0.05% and 0.2% w/w were prepared using an extrusion method. The mechanical, antioxidant, antimicrobial, water vapor and UV-Vis barrier properties, as well as available polyphenolics on the surface, were studied. FT-IR and Raman spectroscopy studies were carried out to analyze the chemical composition of the resulting films. The hydrophobicity, color response, thermal, optical properties, and opacity values were also determined. The results of this study show that the addition of fungal melanin to poly(lactic acid (PLA as a modifier influenced mechanical and water vapor barrier properties depending on melanin concentration. In low concentration, melanin enhanced the mechanical and barrier properties of the modified films, but in larger amounts, the properties were decreased. The UV-Vis barrier properties of PLA/melanin composites were marginally improved. Differential Scanning Calorimetry (DSC analysis indicated that crystallinity of PLA increased by the addition of melanin, but this did not affect the thermal stability of the films. Modified PLA/melanin films showed good antioxidant activity and were active against Enterococcus faecalis, Pseudomonas aeruginosa and Pseudomonas putida. The addition of melanin caused changes in color values, decreasing lightness and increasing the redness and yellowness of films. Based on the results of this study, fungal melanin has good potential to be exploited as a value-added modifier that can improve the overall properties of PLA.

Effect of molecular weight and glass transition on relaxation and release behaviour of poly(DL-lactic acid) tablets

NARCIS (Netherlands)

Steendam, R.; Van Steenbergen, M.J.; Hennink, W.E.; Frijlink, H.W.; Lerk, C.F.

2001-01-01

Different molecular weight grades of poly(DL-lactic acid) were applied as release controlling excipients in tablets for oral drug administration. The role of molecular weight and glass transition in the mechanism of water-induced volume expansion and drug release of PDLA tablets was investigated.

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.

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

International Nuclear Information System (INIS)

Kao, Chia-Tze; Lin, Chi-Chang; Chen, Yi-Wen; Yeh, Chia-Hung; Fang, Hsin-Yuan; Shie, Ming-You

2015-01-01

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

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.

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

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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.

Enhanced D-lactic acid production from renewable resources using engineered Lactobacillus plantarum.

Science.gov (United States)

Zhang, Yixing; Vadlani, Praveen V; Kumar, Amit; Hardwidge, Philip R; Govind, Revathi; Tanaka, Tsutomu; Kondo, Akihiko

2016-01-01

D-lactic acid is used as a monomer in the production of poly-D-lactic acid (PDLA), which is used to form heat-resistant stereocomplex poly-lactic acid. To produce cost-effective D-lactic acid by using all sugars derived from biomass efficiently, xylose-assimilating genes encoding xylose isomerase and xylulokinase were cloned into an L-lactate-deficient strain, Lactobacillus plantarum. The resulting recombinant strain, namely L. plantarum NCIMB 8826 ∆ldhL1-pLEM-xylAB, was able to produce D-lactic acid (at optical purity >99 %) from xylose at a yield of 0.53 g g(-1). Simultaneous utilization of glucose and xylose to produce D-lactic acid was also achieved by this strain, and 47.2 g L(-1) of D-lactic acid was produced from 37.5 g L(-1) glucose and 19.7 g L(-1) xylose. Corn stover and soybean meal extract (SBME) were evaluated as cost-effective medium components for D-lactic acid production. Optimization of medium composition using response surface methodology resulted in 30 % reduction in enzyme loading and 70 % reduction in peptone concentration. In addition, we successfully demonstrated D-lactic acid fermentation from corn stover and SBME in a fed-batch fermentation, which yielded 61.4 g L(-1) D-lactic acid with an overall yield of 0.77 g g(-1). All these approaches are geared to attaining high D-lactic acid production from biomass sugars to produce low-cost, highly thermostable biodegradable plastics.

Long-acting poly(DL:lactic acid-castor oil) 3:7-bupivacaine formulation: effect of hydrophobic additives.

Science.gov (United States)

Sokolsky-Papkov, Marina; Golovanevski, Ludmila; Domb, Abraham J; Weiniger, Carolyn F

2011-12-01

To reduce formulation viscosity of bupivacaine/poly(DL lactic acid co castor oil) 3:7 without increasing bupivacaine release rates. Poly(DL lactic acid) 3:7 was synthesized and bupivacaine formulation prepared by mixing with additives ricinoleic acid or castor oil. In vitro release measurements identified optimum formulation. Anesthetized ICR mice were injected around left sciatic nerve using nerve stimulator with 0.1 mL of formulation. Animals received 10% bupivacaine-polymer formulation with 10% castor oil (p(DLLA:CO)3:7-10% bupi-10% CO) or 15% bupivacaine-polymer with 10% castor oil (p(DLLA:CO)3:7-15% bupi-10% CO). Sensory and motor block were measured. Viscosity of 10% and 15% bupivacaine-p(DLLA:CO)3:7 formulations was reduced using hydrophobic additives; however, castor oil reduced bupivacaine release rates and eliminated burst effect. Less than 10% of the incorporated bupivacaine was released during 6 h, and less than 25% released in 24 h in vitro. In vivo formulation injection resulted in a 24 h motor block and a sensory block lasting at least 72 h. Incorporation of hydrophobic low-viscosity additive reduced viscosity in addition to burst release effects. Bupivacaine-polymer formulation with castor oil additive demonstrated prolonged sensory analgesia in vivo, with reduced duration of motor block.

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)

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

2015-01-01

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

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.

Capillary microreactors for lactic acid extraction: experimental and modelling study

NARCIS (Netherlands)

Susanti, Susanti; Winkelman, Jozef; Schuur, Boelo; Heeres, Hero; Yue, Jun

2015-01-01

Lactic acid is an important biobased chemical and, among others, is used for the production of poly-lactic acid. Down-stream processing using state of the art technology is energy intensive and leads to the formation of large amounts of salts. In this presentation, experimental and modeling studies

Poly(lactic acid Composites Containing Carbon-Based Nanomaterials: A Review

Directory of Open Access Journals (Sweden)

Carolina Gonçalves

2017-07-01

Full Text Available Poly(lactic acid (PLA is a green alternative to petrochemical commodity plastics, used in packaging, agricultural products, disposable materials, textiles, and automotive composites. It is also approved by regulatory authorities for several biomedical applications. However, for some uses it is required that some of its properties be improved, namely in terms of thermo-mechanical and electrical performance. The incorporation of nanofillers is a common approach to attain this goal. The outstanding properties of carbon-based nanomaterials (CBN have caused a surge in research works dealing with PLA/CBN composites. The available information is compiled and reviewed, focusing on PLA/CNT (carbon nanotubes and PLA/GBM (graphene-based materials composites. The production methods, and the effects of CBN loading on PLA properties, namely mechanical, thermal, electrical, and biological, are discussed.

Morphological Evaluation of Soft Tissue Augmentation Using Porous Poly-DL-Lactic Acid With Straight Holes.

Science.gov (United States)

Ken, Yukawa; Noriko, Tachikawa; Furuichi, Akiko; Shohei, Kasugai

2016-12-01

This study investigated the biological reaction to porous poly-DL-lactic acid (PDLLA) scaffolds with holes for soft tissue augmentation. The control group was porous PDLLA with a diameter of 5.0 mm and a height of 2.0 mm. For the 2 test groups, 7 holes were drilled from the upper to the lower base of the scaffolds; the holes had diameters of 0.5 and 1.0 mm. A scaffold was placed in the periosteum of the cranium. The height and molecular weight (Mw) of the scaffolds were measured at 4 and 8 weeks. Hematoxylin and eosin staining was used to measure the connective tissue and blood vessel areas. All groups had similar scaffold heights, but the Mw decreased significantly over time. There were significant differences in the connective tissue and blood vessel areas among the control, 0.5-mm, and 1.0-mm groups at the same time point. The soft tissue was increased by drilling holes in the scaffolds. Porous poly-DL-lactic acid (PDLLA) contributed favorable prognosis for soft tissue. A wider hole was associated with increased connective tissue and blood vessel areas. The scaffold height and Mw were not impacted by size of the holes.

Poly(lactic acid (PLA Based Tear Resistant and Biodegradable Flexible Films by Blown Film Extrusion

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Norma Mallegni

2018-01-01

Full Text Available Poly(lactic acid (PLA was melt mixed in a laboratory extruder with poly(butylene adipate-co-terephthalate (PBAT and poly(butylene succinate (PBS in the presence of polypropylene glycol di glycidyl ether (EJ400 that acted as both plasticizer and compatibilizer. The process was then scaled up in a semi-industrial extruder preparing pellets having different content of a nucleating agent (LAK. All of the formulations could be processed by blowing extrusion and the obtained films showed mechanical properties dependent on the LAK content. In particular the tearing strength showed a maximum like trend in the investigated composition range. The films prepared with both kinds of blends showed a tensile strength in the range 12–24 MPa, an elongation at break in the range 150–260% and a significant crystallinity.

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.

Efficacy and safety of injection with poly-L-lactic acid compared with hyaluronic acid for correction of nasolabial fold: a randomized, evaluator-blinded, comparative study.

Science.gov (United States)

Hyun, M Y; Lee, Y; No, Y A; Yoo, K H; Kim, M N; Hong, C K; Chang, S E; Won, C H; Kim, B J

2015-03-01

Hyaluronic acid (HA) fillers and poly-L-lactic acid (PLA) fillers are frequently used to correct facial wrinkles. To compare the efficacy and safety of a novel injectable poly-L-lactic acid (PLA) filler and a well-studied biphasic HA filler for the treatment of moderate to severe nasolabial folds. In this multicentre, randomized, evaluator-blinded, comparative study, subjects were randomized for injections with PLA or HA into both nasolabial folds. Efficacy was determined by calculating the change in Wrinkle Severity Rating Scale (WSRS) relative to baseline. Local safety was assessed by reported adverse events. At week 24, mean improvement in WSRS from baseline was 2.09 ± 0.68 for the PLA side and 1.54 ± 0.65 for the HA side. Both injections were well tolerated, and the adverse reactions were mild and transient in most cases. PLA provides noninferior efficacy compared with HA 6 months after being used to treat moderate to severe nasolabial folds. © 2014 British Association of Dermatologists.

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.

Heat capacity of poly(lactic acid)

International Nuclear Information System (INIS)

Pyda, M.; Bopp, R.C.; Wunderlich, B.

2004-01-01

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 Θ 1 =574 K, Θ 2 =Θ 3 =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 C p (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

Preparation and Drug-Release Kinetics of Porous Poly(L-lactic acid)/Rifampicin Blend Particles

OpenAIRE

Takashi Sasaki; Hiroaki Matsuura; Kazuki Tanaka

2014-01-01

Porous polymer spheres are promising materials as carriers for controlled drug release. As a new drug-carrier material, blend particles composed of poly(L-lactic acid) (PLLA) and rifampicin were developed using the freeze-drying technique. The blend particles exhibit high porosity with a specific surface area of 10–40 m2 g−1. Both the size and porosity of the particles depend on the concentration of the original solution and on the method of freezing. With respect to the latter, we used the d...

Using microcantilever sensors to measure poly(lactic-co-glycolic acid) plasticization by moisture uptake

DEFF Research Database (Denmark)

Alves, Gustavo Marcati A.; Bose-Goswami, Sanjukta; Mansano, Ronaldo D.

2018-01-01

Polymeric materials absorb water when exposed to humidity or in contact with aqueous solutions. The polymer and water molecules interact, changing the physicochemical parameters of the material; the most noticeable effect is a decreased glass transition temperature (Tg), known as plasticization. We...... used microcantilever sensors to measure the Tg versus moisture content in poly(lactic-co-glycolic acid) (PLGA), a biodegradable polymer used in implants and as a drug carrier. We demonstrate a concomitant measurement of the mass absorption and Tg using nanograms of material and an inexpensive setup...

The characterization of mechanical and surface properties of poly (glycerol-sebacate-lactic acid) during degradation in phosphate buffered saline

Energy Technology Data Exchange (ETDEWEB)

Sun Zhijie [Center for biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China)], E-mail: zhijiesun2005@yahoo.com.cn; Wu Lan; Lu Xili; Meng Zhaoxu; Zheng Yufeng [Center for biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Dong Deli [Department of Pharmacology, Harbin Medical University, Bio-pharmaceutical Key Laboratory of Heilongjiang Province, Harbin 150081 (China)

2008-11-15

The present study synthesized a poly (glycerol-sebacate-lactic acid) (PGSL) with 1:1:0.5 mole ratio of glycerol, sebacate and lactic acid and investigated the degradation characteristics of the polymer in phosphate buffered saline (PBS) at 37 deg. C in vitro by means of mass loss tests, geometry, differential scanning calorimeter (DSC) measurements, tensile analysis and scanning electron microscopy (SEM). The maintained geometry, linear mass loss, and minor crack formation on the surface during degradation characterized both the bulk degradation and surface erosion of the polymer. By day 30 of degradation, the mass lost reached 16%. The elastic modulus, tensile strength and elongation at breakage of PGSL were correlative to the period of degradation.

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.

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

Energy Technology Data Exchange (ETDEWEB)

Lin, Chi-Chang, E-mail: chichang31@thu.edu.tw; 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. - Highlights: • A simple method of preparing electrospun poly(lactic acid) nanofibers coated with polydopamine • Enhanced adhesion and proliferation of hADSCs on a PDA/PLA mat • Increased focal adhesion kinase (FAK), collagen I levels, cell attachment and cell cycle progression with a high PDA content • Up-regulation of the Ang-1 and vWF proteins associated with angiogenesis differentiation of hADSCs is observed. • A promising method for bio-inspired surface modification on organic fiber substrates using PDA.

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

International Nuclear Information System (INIS)

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. - Highlights: • A simple method of preparing electrospun poly(lactic acid) nanofibers coated with polydopamine • Enhanced adhesion and proliferation of hADSCs on a PDA/PLA mat • Increased focal adhesion kinase (FAK), collagen I levels, cell attachment and cell cycle progression with a high PDA content • Up-regulation of the Ang-1 and vWF proteins associated with angiogenesis differentiation of hADSCs is observed. • A promising method for bio-inspired surface modification on organic fiber substrates using PDA

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

Science.gov (United States)

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

2016-05-01

To engineer bone tissue, it is necessary to provide a biocompatible, mechanically robust scaffold. In this study, we fabricated an ultrafine nanofiber scaffold by electrospinning a blend of poly(L-lactic-co-glycolic acid), tussah silk fibroin, and graphene oxide (GO) and characterized its morphology, biocompatibility, mechanical properties, and biological activity. The data indicate that incorporation of 10 wt.% tussah silk and 1 wt.% graphene oxide into poly(L-lactic-co-glycolic acid) nanofibers significantly decreased the fiber diameter from 280 to 130 nm. Furthermore, tussah silk and graphene oxide boosted the Young's modulus and tensile strength by nearly 4-fold and 3-fold, respectively, and significantly enhanced adhesion, proliferation in mouse mesenchymal stem cells and functionally promoted biomineralization-relevant alkaline phosphatase (ALP) and mineral deposition. The results indicate that composite nanofibers could be excellent and versatile scaffolds for bone tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

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)

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

2014-01-01

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. - 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

Effects of poly(L-lactide-ε-caprolactone) and magnesium hydroxide additives on physico-mechanical properties and degradation of poly(L-lactic acid).

Science.gov (United States)

Kang, Eun Young; Lih, Eugene; Kim, Ik Hwan; Joung, Yoon Ki; Han, Dong Keun

2016-01-01

Biodegradable poly(L-lactic acid) (PLLA) is one of the most widely used polymer in biomedical devices, but it still has limitations such as inherent brittleness and acidic degradation products. In this work, PLLA blends with poly(L-lactide-ε-caprolactone) (PLCL) and Mg(OH)2 were prepared by the thermal processing to improve their physico-mechanical and thermal properties. In addition, the neutralizing effect of Mg(OH)2 was evaluated by degradation study. The elongation of PLLA remarkably increased from 3 to 164.4 % and the glass transition temperature (Tg) of PLLA was slightly reduced from 61 to 52 °C by adding PLCL additive. Mg(OH)2 in polymeric matrix not only improved the molecular weight reduction and mechanical strength of PLLA, but also neutralized the acidic byproducts generated during polyester degradation. Therefore, the results demonstrated that the presence of PLCL and Mg(OH)2 additives in PLLA matrix could prevent the thermal decomposition and control degradation behavior of polyester.

Degradation of Poly (lactic acid under Simulated Landfill Conditions

Directory of Open Access Journals (Sweden)

Chomnutcha Boonmee

2017-03-01

Full Text Available In this study, the physical and chemical properties change of poly(lactic acid after burying in the mixture of soil and sludge under thermophilic (61 °C oxygen limited conditions were investigated using various analytical techniques. The environmental factors under these setting conditions and microbial activities accelerated the degradation process of PLA. Under tested conditions, PLA loss their weight about 90% at the burying time of 90 days. During the degradation process, PLA samples were continuously broken to small fragile fragments and showed the size less than 1 mm at the end of degradation test. Change of the surface morphology change was revealed by scanning electron microscopy (SEM. Many pores, cracks and irregular roughness were presented on the PLA surface. Thermal decomposition was decreased from 387.8 to 289.2 °C. The percentage of carbon content in molecular structure decreased from 49.46% to 45.42%. In addition, the Fourier transformed infrared spectroscopy (FTIR revealed the change of ester bonds. This study can be used for developing PLA waste management process.

Characterization of Extruded Poly(lactic acid/Pecan Nutshell Biocomposites

Directory of Open Access Journals (Sweden)

C. R. Álvarez-Chávez

2017-01-01

Full Text Available Pecan nutshells are a solid form of waste obtained from the pecan nut production and they have been explored as an inexpensive filler for incorporation by melt blending into the poly(lactic acid (PLA matrix. The pecan nutshells contain polyphenols, proteins, tannins, sugars, and lipids; some of these components must be released in order to improve adhesion with a polymeric matrix. The physicochemical characterization of the extruded biocomposites of pecan nutshell powder (PNSP at 0, 5, and 7.5% wt. with two treatments (untreated and defatted into PLA is presented in this work. The incorporation of PNSP into the PLA matrix caused a variation in color and density and increased the water absorption. However, some mechanical and thermal parameters of the biocomposites showed a significant decrease. The morphological analysis showed good dispersion and adhesion of the PNSP to the PLA matrix. Based on the results of the characterization, biocomposites formulated with defatted PNSP have a potential to be used as sustainable fillers in PLA biocomposites. These biocomposites have a potential application as food containers, packaging trays, or disposable items.

In vitro degradation of poly (L-co-D,L lactic acid containing PCL-T

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Marcia Adriana Tomaz Duarte

2014-01-01

Full Text Available The application of polymer-based bioresorbable temporary devices in the medical field grows continuously, and professionals from several areas act to solve problems related to body functions lost due to diseases, accidents or natural wear. Here we study the influence from poly(caprolactonetriol (PCL-T on the degeneration process in the copolymer poly(L-co-DL-lactic acid (PLDLA membrane, by producing PLDLA/PCL-T blends with 90/10, 70/30 and 50/50 relative concentrations. The data for in vitro degradation showed that PCL-T decreases the rate of PLDLA. This was obtained with the following techniques: Differential Scanning Calorimetry (DSC, Thermogravimetric Analysis (TGA, Gel Permeation Chromatography (GPC and Scanning Electron Microscopy (SEM. Therefore, it is possible to vary the membrane degradation rate by changing the blend composition, which is a tool to tailor a biomaterial.

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

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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...

Preparation of Cotton-Wool-Like Poly(lactic acid-Based Composites Consisting of Core-Shell-Type Fibers

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Jian Wang

2015-11-01

Full Text Available In previous works, we reported the fabrication of cotton-wool-like composites consisting of siloxane-doped vaterite and poly(l-lactic acid (SiVPCs. Various irregularly shaped bone voids can be filled with the composite, which effectively supplies calcium and silicate ions, enhancing the bone formation by stimulating the cells. The composites, however, were brittle and showed an initial burst release of ions. In the present work, to improve the mechanical flexibility and ion release, the composite fiber was coated with a soft, thin layer consisting of poly(d,l-lactic-co-glycolic acid (PLGA. A coaxial electrospinning technique was used to prepare a cotton-wool-like material comprising “core-shell”-type fibers with a diameter of ~12 µm. The fibers, which consisted of SiVPC coated with a ~2-µm-thick PLGA layer, were mechanically flexible; even under a uniaxial compressive load of 1.5 kPa, the cotton-wool-like material did not exhibit fracture of the fibers and, after removing the load, showed a ~60% recovery. In Tris buffer solution, the initial burst release of calcium and silicate ions from the “core-shell”-type fibers was effectively controlled, and the ions were slowly released after one day. Thus, the mechanical flexibility and ion-release behavior of the composites were drastically improved by the thin PLGA coating.

Plasticized poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends incorporated with catechin intended for active food-packaging applications.

Science.gov (United States)

Arrieta, Marina Patricia; Castro-López, María del Mar; Rayón, Emilio; Barral-Losada, Luis Fernando; López-Vilariño, José Manuel; López, Juan; González-Rodríguez, María Victoria

2014-10-15

Active biobased packaging materials based on poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends were prepared by melt blending and fully characterized. Catechin incorporation, as antioxidant compound, enhanced the thermal stability, whereas its release was improved by the addition of acetyl(tributyl citrate) (ATBC) as plasticizer. Whereas the incorporation of ATBC resulted in a reduction of elastic modulus and hardness, catechin addition produced more rigid materials due to hydrogen-bonding interactions between catechin hydroxyl groups and carbonyl groups of PLA and PHB. The quantification of catechin released into a fatty food simulant and the antioxidant effectiveness after the release process were demonstrated. The effect of the materials' exposure to a food simulant was also investigated. PHB-added materials maintained their structural and mechanical properties after 10 days in a test medium that represents the worst foreseeable conditions of the intended use. Thus, plasticized PLA-PHB blends with catechin show their potential as biobased active packaging for fatty food.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

L-Lactic Acid Production by Lactobacillus rhamnosus ATCC 10863

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Ana Lívia Chemeli Senedese

2015-01-01

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

Kinetics of free radical decay reactions in lactic acid homo and copolymers irradiated to sterilization dose

International Nuclear Information System (INIS)

Kantoglu, O.; Ozbey, T.; Gueven, O.

1995-01-01

The kinetics of free radical decay reactions of poly(L-Lactic acid), poly(DL-Lactic acid) and random copolymer of lactic and glycolic acid have been investigated for decays taking place in air and in vacuum. The change in ESR lines of γ-irradiated polymers have been followed over a long time period. The decay has been found to follow neither simple first-order nor second-order kinetics. Various kinetic approaches including composite first or second-order mechanisms and diffusion-controlled first or second-order equations were determined to be also unsatisfactory. The decay of radicals in bulk irradiated lactic acid homo and copolymers was found to be best described when the second-order non-classical equation with time dependent rate constant approach was used. (Author)

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid).

Science.gov (United States)

Deng, Meng; Nair, Lakshmi S; Nukavarapu, Syam P; Kumbar, Sangamesh G; Jiang, Tao; Krogman, Nicholas R; Singh, Anurima; Allcock, Harry R; Laurencin, Cato T

2008-01-01

Previously we demonstrated the ability of ethyl glycinato substituted polyphosphazenes to neutralize the acidic degradation products and control the degradation rate of poly(lactic acid-glycolic acid) (PLAGA) by blending. In this study, blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA(50)PhPh(50)) and 85:15 PLAGA were prepared using a mutual solvent approach. Three different solvents, methylene chloride (MC), chloroform (CF) and tetrahydrofuran (THF) were studied to investigate solvent effects on blend miscibility. Three different blends were then fabricated at various weight ratios namely 25:75 (BLEND25), 50:50 (BLEND50), and 75:25 (BLEND75) using THF as the mutual solvent. The miscibility of the blends was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Among these, BLEND25 was miscible while BLEND50 and BLEND75 were partially miscible. Furthermore, BLEND25 formed apatite layers on its surface as evidenced in a biomimetic study performed. These novel blends showed cell adhesion and proliferation comparable to PLAGA. However, the PNEA(50)PhPh(50) component in the blends was able to increase the phenotypic expression and mineralized matrix synthesis of the primary rat osteoblasts (PRO) in vitro. Blends of high strength PNEA(50)PhPh(50) and 85:15 PLAGA are promising biomaterials for a variety of musculoskeletal applications.

Effect of Commercial SiO2 and SiO2 from rice husk ash loading on biodegradation of Poly (lactic acid) and crosslinked Poly (lactic acid)

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Prapruddivongs, C.; Apichartsitporn, M.; Wongpreedee, T.

2017-09-01

In this work, biodegradation behavior of poly (lactic acid) (PLA) and crosslinked PLA filled with two types of SiO2, precipitated SiO2 (commercial SiO2) and SiO2 from rice husk ash, were studied. Rice husks were first treated with 2 molar hydrochloric acid (HCl) to produce high purity SiO2, before burnt in a furnace at 800°C for 6 hours. All components were melted bending by an internal mixer then hot pressed using compression molder to form tested specimens. FTIR spectra of SiO2 and PLA samples were investigated. The results showed the lack of silanol group (Si-OH) of rice husk ash after steric acid surface modification, while the addition of particles can affect the crosslinking of the PLA. For biodegradation test by evaluating total amount of carbon dioxide (CO2) evolved during 60 days incubation at a controlled temperature of 58±2°C, the results showed that the biodegradation of crosslinked PLA occurred slower than the neat PLA. However, SiO2 incorporation enhanced the degree of biodegradation In particular, introducing commercial SiO2 in PLA and crosslinked PLA tended to clearly increase the degree of biodegradation as a consequence of the more accelerated hydrolysis degradation.

Delivery of vanillin by poly(lactic-acid) nanoparticles: Development, characterization and in vitro evaluation of antioxidant activity

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Dalmolin, Luciana Facco; Khalil, Najeh Maissar; Mainardes, Rubiana Mara, E-mail: rubianamainardes@hotmail.com

2016-05-01

Poly(lactic acid) (PLA) nanoparticles containing vanillin were prepared using an emulsion-solvent evaporation technique and were characterized and assessed for their in vitro antioxidant potential. Physicochemical properties of the nanoparticles were characterized by size, polydispersity index, zeta potential, encapsulation efficiency and stability. Solid state and thermal properties were assessed using X-ray diffraction and differential scanning calorimetry, while in vitro drug release profile was also evaluated. Results showed PLA nanoparticles having a characteristic amorphous structure, sizes in the range of 240 nm with high homogeneity in size distribution, zeta potential of − 22 mV and vanillin encapsulation efficiency of 41%. In vitro release study showed a slow and sustained release of vanillin governed by diffusion. Nanoparticles were stable over a period of three months. Antioxidant ability of the vanillin-loaded PLA nanoparticles in scavenging the radical 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was inferior to free vanillin and due to its prolonged release showed a profile that was both time and concentration dependent, while free vanillin showed concentration-dependent activity. The study concluded that PLA nanoparticles are potential carriers for vanillin delivery. - Highlights: • Vanillin was nanoencapsulated in poly(lactic acid) (PLA) nanoparticles. • Mean particle size was 240 nm and vanillin encapsulation efficiency was 41%. • A prolonged and biphasic vanillin release occurred with 20% released after 120 h. • Vanillin nanoparticles exhibited time/concentration dependent antioxidant activity.

Delivery of vanillin by poly(lactic-acid) nanoparticles: Development, characterization and in vitro evaluation of antioxidant activity

International Nuclear Information System (INIS)

Dalmolin, Luciana Facco; Khalil, Najeh Maissar; Mainardes, Rubiana Mara

2016-01-01

Poly(lactic acid) (PLA) nanoparticles containing vanillin were prepared using an emulsion-solvent evaporation technique and were characterized and assessed for their in vitro antioxidant potential. Physicochemical properties of the nanoparticles were characterized by size, polydispersity index, zeta potential, encapsulation efficiency and stability. Solid state and thermal properties were assessed using X-ray diffraction and differential scanning calorimetry, while in vitro drug release profile was also evaluated. Results showed PLA nanoparticles having a characteristic amorphous structure, sizes in the range of 240 nm with high homogeneity in size distribution, zeta potential of − 22 mV and vanillin encapsulation efficiency of 41%. In vitro release study showed a slow and sustained release of vanillin governed by diffusion. Nanoparticles were stable over a period of three months. Antioxidant ability of the vanillin-loaded PLA nanoparticles in scavenging the radical 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was inferior to free vanillin and due to its prolonged release showed a profile that was both time and concentration dependent, while free vanillin showed concentration-dependent activity. The study concluded that PLA nanoparticles are potential carriers for vanillin delivery. - Highlights: • Vanillin was nanoencapsulated in poly(lactic acid) (PLA) nanoparticles. • Mean particle size was 240 nm and vanillin encapsulation efficiency was 41%. • A prolonged and biphasic vanillin release occurred with 20% released after 120 h. • Vanillin nanoparticles exhibited time/concentration dependent antioxidant activity.

Lactic Acid Yield Using Different Bacterial Strains, Its Purification, and Polymerization through Ring-Opening Reactions

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F. G. Orozco

2014-01-01

Full Text Available Laboratory-scale anaerobic fermentation was performed to obtain lactic acid from lactose, using five lactic acid bacteria: Lactococcus lactis, Lactobacillus bulgaricus, L. delbrueckii, L. plantarum, and L. delbrueckii lactis. A yield of 0.99 g lactic acid/g lactose was obtained with L. delbrueckii, from which a final concentration of 80.95 g/L aqueous solution was obtained through microfiltration, nanofiltration, and inverse osmosis membranes. The lactic acid was polymerized by means of ring-opening reactions (ROP to obtain poly-DL-lactic acid (PDLLA, with a viscosity average molecular weight (Mv of 19,264 g/mol.

Biologically Safe Poly(l-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties.

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Oyama, Hideko T; Tanishima, Daisuke; Ogawa, Ryohei

2017-04-10

Although poly(l-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.

Film Sensor Device Fabricated by a Piezoelectric Poly(L-lactic acid) Film

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Ando, Masamichi; Kawamura, Hideki; Kageyama, Keisuke; Tajitsu, Yoshiro

2012-09-01

Synthetic piezoelectric polymer films produced from petroleum feedstock have long been used as thin-film sensors and actuators. However, the fossil fuel requirements for synthetic polymer production and carbon dioxide emission from its combustion have raised concern about the environmental impact of its continued use. Eco-friendly biomass polymers, such as poly(L-lactic acid) (PLLA), are made from plant-based (vegetable starch) plastics and, thus, have a much smaller carbon footprint. Additionally, PLLA does not exhibit pyroelectricity or unnecessary poling. This suggests the usefulness of PLLA films for the human-machine interface (HMI). As an example of a new HMI, we have produced a TV remote control using a PLLA film. The intuitive operation provided by this PLLA device suggests that it is useful for the elderly or handicapped.

Electrospun poly(lactic acid) based conducting nanofibrous networks

International Nuclear Information System (INIS)

Patra, S N; Bhattacharyya, D; Ray, S; Easteal, A J

2009-01-01

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.

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...

The effect of γ-rays irradiation on poly (L-lactic acid)

International Nuclear Information System (INIS)

Peng Chaorong; Chen Hao; Wang Jingxia; Wu Ling; Chen Zhuping; Deng Huachuan

2008-01-01

Poly (L-lactic acid) was irradiated by γ-rays. The effects of absorbed dose on viscosity average molecular weight, crystallization and thermal weight loss in irradiated condition under vacuum, nitrogen, air and oxygen were investigated, which were characterized by using ubbelohde viscometer, differential scamming calorimeter (DSC), polarized microscope and thermogravimetry analysis (TGA). Viscosity average molecular weight of PLLA decreases with increment of absorbed dose and viscosity average molecular weight of PLLA irradiated in vacuum is highest among the different irradiated condition at same absorbed dose. Both degree and rates of crystallization increase with increment of absorbed dose and TGA curves of PLLA irradiated under vacuum or nitrogen are shifted towards higher temperature compare with un-irradiated sample at the absorbed dose from 6-40kGy. The weight loss of PLLA irradiated under oxygen is lower than that under vacuum at absorbed dose of 6kGy. (authors)

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

Science.gov (United States)

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

2015-05-01

The search for ideal biomaterials is still on-going for tissue regeneration. In this study, blends of poly ε-caprolactone (PCL) with poly l-lactic acid (PLLA), nalidixic acid (NA) and polyethylene glycol (PEG) were prepared. Mechanical and thermal properties of the blends were investigated by tensile and flexural analysis, DSC, TGA, WXRD, MFI, BET, SEM and hot stage optical microscopy. Results showed that the loading of PLLA caused a significant decrease in tensile strength and almost total eradication of the elongation at break of PCL matrix, especially after PEG and NA addition. Increased stiffness was also noted with additional NA, PEG and PLLA, resulting in an increase in the flexural modulus of the blends. Isothermal degradation indicated that bulk PCL, PLLA and the blends were thermally stable at 200°C for the duration of 2h making extrusion of the blends at this temperature viable. Morphological study showed that increasing the PLLA content and addition of the very low viscosity PEG and powder NA decreased the Melt Flow Indexer and increased the viscosity. At the higher temperature, the PLLA begins to soften and eventually melts allowing for increased flow and, coupling this with, the natural increase in MFI caused by temperature is enhanced further. The PEG and NA addition increased dramatically the pore volume which is important for cell growth and flow transport of nutrients and metabolic waste. Copyright © 2015 Elsevier Ltd. All rights reserved.

Three-dimensional wet-electrospun poly(lactic acid)/multi-wall carbon nanotubes scaffold induces differentiation of human menstrual blood-derived stem cells into germ-like cells.

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Eyni, Hossein; Ghorbani, Sadegh; Shirazi, Reza; Salari Asl, Leila; P Beiranvand, Shahram; Soleimani, Masoud

2017-09-01

Infertility caused by the disruption or absence of germ cells is a major and largely incurable medical problem. Germ cells (i.e., sperm or egg) play a key role in the transmission of genetic and epigenetic information across generations. Generation of gametes derived in vitro from stem cells hold promising prospects which could potentially help infertile men and women. Menstrual blood-derived stem cells are a unique stem cell source. Evidence suggests that menstrual blood-derived stem cells exhibit a multi-lineage potential and have attracted extensive attention in regenerative medicine. To maintain the three-dimensional structure of natural extra cellular matrices in vitro, scaffolds can do this favor and mimic a microenvironment for cell proliferation and differentiation. According to previous studies, poly(lactic acid) and multi-wall carbon nanotubes have been introduced as novel and promising biomaterials for the proliferation and differentiation of stem cells. Some cell types have been successfully grown on a matrix containing carbon nanotubes in tissue engineering but there is no report for this material to support stem cells differentiation into germ cells lineage. This study designed a 3D wet-electrospun poly(lactic acid) and poly(lactic acid)/multi-wall carbon nanotubes composite scaffold to compare infiltration, proliferation, and differentiation potential of menstrual blood-derived stem cells toward germ cell lineage with 2D culture. Our primary data revealed that the fabricated scaffold has mechanical and biological suitable qualities for supporting and attachments of stem cells. The differentiated menstrual blood-derived stem cells tracking in scaffolds using scanning electron microscopy confirmed cell attachment, aggregation, and distribution on the porous scaffold. Based on the differentiation assay by RT-PCR analysis, stem cells and germ-like cells markers were expressed in 3D groups as well as 2D one. It seems that poly(lactic acid

Electrospun Poly(lactic acid-co-glycolic acid) Scaffolds for Skin Tissue Engineering

Science.gov (United States)

Kumbar, Sangamesh G.; Nukavarapu, Syam Prasad; James, Roshan; Nair, Lakshmi S.; Laurencin, Cato T.

2008-01-01

Electrospun fiber matrices composed of scaffolds of varying fiber diameters were investigated for potential application of severe skin loss. Few systematic studies have been performed to examine the effect of varying fiber diameter electrospun fiber matrices for skin regeneration. The present study reports the fabrication of poly[lactic acid-co-glycolic acid] (PLAGA) matrices with fiber diameters of 150–225, 200–300, 250–467, 500–900, 600–1200, 2500–3000 and 3250–6000 nm via electrospinning. All fiber matrices found to have a tensile modulus from 39.23 ± 8.15 to 79.21 ± 13.71 MPa which falls in the range for normal human skin. Further, the porous fiber matrices have porosity between 38–60 % and average pore diameters between 10–14µm. We evaluated the efficacy of these biodegradable fiber matrices as skin substitutes by seeding them with human skin fibroblasts (hSF). Human skin fibroblasts acquired a well spread morphology and showed significant progressive growth on fiber matrices in the 350–1100 nm diameter range. Collagen type III gene expression was significantly up-regulated in hSF seeded on matrices with fiber diameters in the range of 350–1100 nm. Based on the need, the proposed fiber skin substitutes can be successfully fabricated and optimized for skin fibroblast attachment and growth. PMID:18639927

Poly (lactic acid organoclay nano composites for paper coating applications

Directory of Open Access Journals (Sweden)

Tatcha Sonjui

2014-10-01

Full Text Available 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 and thermal properties. The objectives of this research were to prepare PLA formulations using three different PLAs. The formulas giving high gloss coating film were selected to prepare nano composite film by incorporated with different amount of various types of organoclays. The physical properties of the PLA coating films were studied and it was found that the PLA 7000D with 0.1%w/w of Cloisite 30B provided decent viscosity for coating process. In addition, the nano composite coating films showed good physical properties such as high gloss, good adhesion, and good hardness. There is a possibility of using the obtained formulation as a paper coating film.

Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

Energy Technology Data Exchange (ETDEWEB)

Zou, Wei, E-mail: zw55624@163.com; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping, E-mail: jpqu@scut.edu.cn [National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640 (China)

2016-03-09

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.

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

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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.

The PM2.5 capture of poly (lactic acid)/nano MOFs eletrospinning membrane with hydrophilic surface

Science.gov (United States)

Wang, Yating; Dai, Xiu; Li, Xu; Wang, Xinlong

2018-03-01

In this article, metal organic frameworks (MOFs) material is introduced in the poly (lactic acid) (PLA) by electrospinning to fabricate the nanocomposite membrane. The acrylic acid (AA) is grafted onto the membrane under UV light. The prepared membrane is studied by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermogravimetry (TG), contact angle test and tensile strength test. The SEM image and XRD indicate that nano MOFs particles adhere to the membrane. Contact angle test shows that grafting AA on the composite fiber membrane improves its hydrophilicity effectively. TG analyses show that the particulate matter (PM) capture capacity of PLA membrane with 2 wt% ZIF-8 content is 22%, which rises to 37% after grafting.

Biodegradable and thermosensitive monomethoxy poly(ethylene glycol)-poly(lactic acid) hydrogel as a barrier for prevention of post-operative abdominal adhesion.

Science.gov (United States)

Fu, Shao Zhi; Li, Zhi; Fan, Jun Ming; Meng, Xiao Hang; Shi, Kun; Qu, Ying; Yang, Ling Lin; Wu, Jing Bo; Fan, Juan; Luot, Feng; Qian, Zhi Yong

2014-03-01

Post-operative peritoneal adhesions are serious consequences of abdominal or pelvic surgery and cause severe bowel obstruction, chronic pelvic pain and infertility. In this study, a novel nano-hydrogel system based on a monomethoxy poly(ethylene glycol)-poly(lactic acid) (MPEG-PLA) di-block copolymer was studied for its ability to prevent abdominal adhesion in rats. The MPEG-PLA hydrogel at a concentration of 40% (w/v) was injected and was able to adhere to defect sites at body temperature. The ability of the hydrogel to inhibit adhesion of post-operative tissues was evaluated by utilizing a rat model of abdominal sidewall-cecum abrasion. It was possible to heal wounded tissue through regeneration of neo-peritoneal tissues ten days after surgery. Our data showed that this hydrogel system is equally as effective as current commercialized anti-adhesive products.

Enhanced L-(+)-lactic acid production by an adapted strain of Rhizopus oryzae using corncob hydrolysate

DEFF Research Database (Denmark)

Bai, Dongmei; Li, S.Z.; Liu, Z.L.

2008-01-01

-added production of a variety of bioproducts. Lactic acid can be used as a precursor for poly-lactic acid production. Although current industrial lactic acid is produced by lactic acid bacteria using enriched medium, production by Rhizopus oryzae is preferred due to its exclusive formation of the......-isomer and a simple nutrition requirement by the fungus. Production of-L-(+)-lactic acid by R. oryzae using xylose has been reported; however, its yield and conversion rate are poor compared with that of using glucose. In this study, we report an adapted R. oryzae strain HZS6 that significantly improved efficiency...... of substrate utilization and enhanced production of L-(+)-lactic acid from corncob hydrolysate. It increased L-(+)-lactic acid final concentration, yield, and volumetric productivity more than twofold compared with its parental strain. The optimized growth and fermentation conditions for Strain HZS6 were...

Intermolecular interactions between B. mori silk fibroin and poly(L-lactic acid) in electrospun composite nanofibrous scaffolds

Energy Technology Data Exchange (ETDEWEB)

Taddei, Paola, E-mail: paola.taddei@unibo.it [Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Via Belmeloro 8/2, 40126 Bologna (Italy); Tozzi, Silvia [Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Via Belmeloro 8/2, 40126 Bologna (Italy); Zuccheri, Giampaolo [Dipartimento di Farmacia e Biotecnologie e Centro Interdipartimentale di Ricerca Industriale Scienze della Vita e Tecnologie per la Salute, Università di Bologna, Via Irnerio 48, 40126 Bologna (Italy); Centro S3, Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (Italy); Martinotti, Simona; Ranzato, Elia [Dipartimento di Scienze e Innovazione Tecnologica, DiSIT, Università del Piemonte Orientale, viale Teresa Michel 11, 15121 Alessandria (Italy); Chiono, Valeria; Carmagnola, Irene [Dipartimento di Ingegneria Meccanica e Aerospaziale, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Tsukada, Masuhiro [Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567 (Japan)

2017-01-01

In this study, composite nanofibrous scaffolds were obtained by electrospinning a trifluoroacetic acid solution containing B. mori silk fibroin (SF) and poly(L-lactic acid) (PLLA) in a 1:1 weight ratio. SF, PLLA and SF/PLLA nanofibres were prepared with average diameter sizes of 360 ± 90 nm, 470 ± 240 nm and 580 ± 220 nm, respectively, as assessed by SEM analysis. Vibrational and thermal analyses showed that upon blending in the SF/PLLA nanofibres, the crystallisation of PLLA was hindered by the presence of SF, which crystallized preferentially and underwent conformational changes that did not significantly change its prevailing β-sheet structure. The two components were thermodynamically compatible and the intermolecular interactions between them were revealed for the first time. Human keratinocytes were cultured on nanofibres and their viability and proliferation were determined. Preliminary in vitro tests showed that the incorporation of SF into the PLLA component enhanced cell adhesion and proliferation with respect to the unfunctionalised material. SF has been successfully used to modify the biomaterial properties and confirmed to be an efficient bioactive protein to mediate cell-biomaterial interaction. - Highlights: • Composite silk fibroin-poly(L-lactic acid) scaffolds were obtained by electrospinning. • Intermolecular interactions between SF and PLLA were revealed for the first time. • Upon blending, the crystallisation of PLLA was hindered by the presence of SF. • SF crystallized preferentially and maintained its prevailing β-sheet structure. • The incorporation of SF into PLLA enhanced human keratinocytes adhesion and proliferation.

Processing Conditions, Thermal and Mechanical Responses of Stretchable Poly (Lactic Acid)/Poly (Butylene Succinate) Films.

Science.gov (United States)

Fortunati, Elena; Puglia, Debora; Iannoni, Antonio; Terenzi, Andrea; Kenny, José Maria; Torre, Luigi

2017-07-16

Poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) based films containing two different plasticizers [Acetyl Tributyl Citrate (ATBC) and isosorbide diester (ISE)] at three different contents (15 wt %, 20 wt % and 30 wt %) were produced by extrusion method. Thermal, morphological, mechanical and wettability behavior of produced materials was investigated as a function of plasticizer content. Filmature parameters were also adjusted and optimized for different formulations, in order to obtain similar thickness for different systems. Differential scanning calorimeter (DSC) results and evaluation of solubility parameter confirmed that similar miscibility was obtained for ATBC and ISE in PLA, while the two selected plasticizers resulted as not efficient for plasticization of PBS, to the limit that the PBS-30ATBC resulted as not processable. On the basis of these results, isosorbide-based plasticizer was considered a suitable agent for modification of a selected blend (PLA/PBS 80:20) and two mixing approaches were used to identify the role of ISE in the plasticization process: results from mechanical analysis confirmed that both produced PLA-PBS blends (PLA85-ISE15)-PBS20 and (PLA80-PBS20)-ISE15 could guarantee advantages in terms of deformability, with respect to the PLA80-PBS20 reference film, suggesting that the promising use of these stretchable PLA-PBS based films plasticized with isosorbide can provide novel solutions for food packaging applications.

Poly(ester amide)s based on (L)-lactic acid oligomers and α-amino acids: influence of the α-amino acid side chain in the poly(ester amide)s properties.

Science.gov (United States)

Fonseca, Ana C; Coelho, Jorge F J; Valente, Joana F A; Correia, Tiago R; Correia, Ilídio J; Gil, Maria H; Simões, Pedro N

2013-01-01

Novel biodegradable and low cytotoxic poly(ester amide)s (PEAs) based on α-amino acids and (L)-lactic acid (L-LA) oligomers were successfully synthesized by interfacial polymerization. The chemical structure of the new polymers was confirmed by spectroscopic analyses. Further characterization suggests that the α-amino acid plays a critical role on the final properties of the PEA. L-phenylalanine provides PEAs with higher glass transition temperature, whereas glycine enhances the crystallinity. The hydrolytic degradation in PBS (pH = 7.4) at 37 °C also depends on the α-amino acid, being faster for glycine-based PEAs. The cytotoxic profiles using fibroblast human cells indicate that the PEAs did not elicit an acute cytotoxic effect. The strategy presented in this work opens the possibility of synthesizing biodegradable PEAs with low citotoxicity by an easy and fast method. It is worth to mention also that the properties of these materials can be fine-tuned only by changing the α-amino acid.

Thermal Degradation and Kinetic Parameters of Polyester and Poly(Lactic Acid) Blends Used in Shopping Bags in Brazil

OpenAIRE

Araújo Junior, J.; Magalhães, D; Oliveira, N. A.; Wiebeck, Helio; Matos, J. R.

2014-01-01

In this work, synthetic polyester and poly(lactic acid) blends used as biodegradable shopping plastic bags were studied, together with control samples of polyethylene containing pro-oxidant catalysts (called “oxidegradable bags” in the market). Samples of these materials were weighed and buried in simulated soil for 3 months, and then studied by Thermal Analysis including a non-isothermal kinetic analysis. It was observed that although there was no significant mass loss in the period of the a...

Composite poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration

International Nuclear Information System (INIS)

Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

2012-01-01

Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/Collagen (PLLA/PAA/Col I and III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p ≤ 0.05) in PLLA/PAA/Col I and III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I and III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I and III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues. - Highlights: ► Differentiation of adipose derived stem cells in the presence of bFGF for wound healing ► Introduction of PAA as ECM mimetic cell binding moiety ► Combination of PLLA/PAA/Col I and III nanofibers and stem cell therapy for skin regeneration.

Composite poly-L-lactic acid/poly-({alpha},{beta})-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration

Energy Technology Data Exchange (ETDEWEB)

Ravichandran, Rajeswari [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Venugopal, Jayarama Reddy, E-mail: nnijrv@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Sundarrajan, Subramanian [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Mukherjee, Shayanti [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Sridhar, Radhakrishnan [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Ramakrishna, Seeram, E-mail: seeram@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore)

2012-08-01

Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-({alpha},{beta})-DL-aspartic acid/Collagen (PLLA/PAA/Col I and III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p {<=} 0.05) in PLLA/PAA/Col I and III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I and III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I and III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues. - Highlights: Black-Right-Pointing-Pointer Differentiation of adipose derived stem cells in the presence of bFGF for wound healing Black-Right-Pointing-Pointer Introduction of PAA as ECM mimetic cell binding moiety Black-Right-Pointing-Pointer Combination of PLLA/PAA/Col I and III nanofibers and stem cell therapy for skin regeneration.

Development of Poly Lactic/Glycolic Acid (PLGA Microspheres for Controlled Release of Rho-Associated Kinase Inhibitor

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Sho Koda

2017-01-01

Full Text Available Purpose. The purpose of this study was to investigate the feasibility of poly lactic/glycolic acid (PLGA as a drug delivery carrier of Rho kinase (ROCK inhibitor for the treatment of corneal endothelial disease. Method. ROCK inhibitor Y-27632 and PLGA were dissolved in water with or without gelatin (W1, and a double emulsion [(W1/O/W2] was formed with dichloromethane (O and polyvinyl alcohol (W2. Drug release curve was obtained by evaluating the released Y-27632 by using high performance liquid chromatography. PLGA was injected into the anterior chamber or subconjunctiva in rabbit eyes, and ocular complication was evaluated by slitlamp microscope and histological analysis. Results. Y-27632 incorporated PLGA microspheres with different molecular weights, and different composition ratios of lactic acid and glycolic acid were fabricated. A high molecular weight and low content of glycolic acid produced a slower and longer release. The Y-27632 released from PLGA microspheres significantly promoted the cell proliferation of cultured corneal endothelial cells. The injection of PLGA did not induce any evident eye complication. Conclusions. ROCK inhibitor-incorporated PLGA microspheres were fabricated, and the microspheres achieved the sustained release of ROCK inhibitor over 7–10 days in vitro. Our data should encourage researchers to use PLGA microspheres for treating corneal endothelial diseases.

Formulation and characterization of poly(propylacrylic acid)/poly(lactic-co-glycolic acid) blend microparticles for pH-dependent membrane disruption and cytosolic delivery.

Science.gov (United States)

Fernando, Lawrence P; Lewis, Jamal S; Evans, Brian C; Duvall, Craig L; Keselowsky, Benjamin G

2018-04-01

Poly(lactic-co-glycolic acid) (PLGA) is widely used as a vehicle for delivery of pharmaceutically relevant payloads. PLGA is readily fabricated as a nano- or microparticle (MP) matrix to load both hydrophobic and hydrophilic small molecular drugs as well as biomacromolecules such as nucleic acids and proteins. However, targeting such payloads to the cell cytosol is often limited by MP entrapment and degradation within acidic endolysosomes. Poly(propylacrylic acid) (PPAA) is a polyelectrolyte polymer with the membrane disruptive capability triggered at low pH. PPAA has been previously formulated in various carrier configurations to enable cytosolic payload delivery, but requires sophisticated carrier design. Taking advantage of PPAA functionality, we have incorporated PPAA into PLGA MPs as a simple polymer mixture to enhance cytosolic delivery of PLGA-encapsulated payloads. Rhodamine loaded PLGA and PPAA/PLGA blend MPs were prepared by a modified nanoprecipitation method. Incorporation of PPAA into PLGA MPs had little to no effect on the size, shape, or loading efficiency, and evidenced no toxicity in Chinese hamster ovary epithelial cells. Notably, incorporation of PPAA into PLGA MPs enabled pH-dependent membrane disruption in a hemolysis assay, and a three-fold increased endosomal escape and cytosolic delivery in dendritic cells after 2 h of MP uptake. These results demonstrate that a simple PLGA/PPAA polymer blend is readily fabricated into composite MPs, enabling cytosolic delivery of an encapsulated payload. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1022-1033, 2018. © 2017 Wiley Periodicals, Inc.

Reduction of Inflammatory Responses and Enhancement of Extracellular Matrix Formation by Vanillin-Incorporated Poly(Lactic-co-Glycolic Acid) Scaffolds

OpenAIRE

Lee, Yujung; Kwon, Jeongil; Khang, Gilson; Lee, Dongwon

2012-01-01

Vanillin is one of the major components of vanilla, a commonly used flavoring agent and preservative and is known to exert potent antioxidant and anti-inflammatory activities. In this work, vanillin-incorporated poly(lactic-co-glycolic acid) (PLGA) films and scaffolds were fabricated to evaluate the effects of vanillin on the inflammatory responses and extracellular matrix (ECM) formation in vitro and in vivo. The incorporation of vanillin to PLGA films induced hydrophilic nature, resulting i...

Aluminum Silicate Nanotube Modification of Cotton-Like Siloxane-poly(L-lactic acid-vaterite Composites

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Daiheon Lee

2013-01-01

Full Text Available In our earlier work, a cotton-like biodegradable composite, consisting of poly(L-lactic acid with siloxane-containing vaterite, has been prepared by electrospinning. In the present work, the fibers skeleton of the cotton-like composites was modified successfully with imogolite, which is hydrophilic and biocompatible, via a dip process using ethanol diluted solution to improve the cellular initial attachment. Almost no change in the fiber morphology after the surface modification was observed. The surface-modified composite showed the similar calcium and silicate ions releasabilities, for activating the osteoblasts, as an unmodified one. Cell culture tests showed that the initial adhesion of murine osteoblast-like cells on the surface of the fibers was enhanced by surface modification.

Poly (Lactic Acid)/Layered Silicate Nanocomposite Films: Effect of Irradiation

Energy Technology Data Exchange (ETDEWEB)

Dadbin, S.; Naimian, F.; Akhavan, A.; Hasanpoor, S., E-mail: sdadbin@yahoo.com, E-mail: sdadbin@aeoi.org.ir [Atomic Energy Organization of Iran (AEOI), Nuclear Science and Technology Research Institute, P.O. Box 11365-8486, Tehran, North Kargar (Iran, Islamic Republic of)

2010-07-01

Poly (Lactic acid) –layered silicate nanocomposite films were prepared by solution casting method. The films were irradiated with Co{sup 60} radiation facility at dose of 30 kGy. The effect of gamma irradiation on mechanical properties of the neat PLA and nanocomposites was evaluated by data obtained from tensile testing measurements. The tensile strength of the irradiated PLA films increased with addition of 1 wt% Triallyl Cyanurate (TAC) indicating crosslink formation. Significant ductile behavior was observed in the PLA nanocomposites containing 4 pph of nanoclay. Incorporation of nanoclay particles in the PLA matrix stimulated crystal growth as it was studied by differential scanning calorimetry (DSC). The morphology of the nanocomposites characterized by transmission electron microscopy (TEM) and X- ray diffraction (XRD) revealed an exfoliated morphology in the PLA nanocomposite films containing 4 pph of nanoclay. Only very small changes were observed in the chemical structure of the irradiated samples as it was investigated by Fourier transform infrared (FTIR) spectroscopy. Enzymatic degradation rate of PLA and its nanocomposite decreased with increasing crystallinity of the samples. The rate of weight loss was also affected by the morphology of the nanocomposites. (author)

Poly (Lactic Acid)/Layered Silicate Nanocomposite Films: Effect of Irradiation

International Nuclear Information System (INIS)

Dadbin, S.; Naimian, F.; Akhavan, A.; Hasanpoor, S.

2010-01-01

Poly (Lactic acid) –layered silicate nanocomposite films were prepared by solution casting method. The films were irradiated with Co 60 radiation facility at dose of 30 kGy. The effect of gamma irradiation on mechanical properties of the neat PLA and nanocomposites was evaluated by data obtained from tensile testing measurements. The tensile strength of the irradiated PLA films increased with addition of 1 wt% Triallyl Cyanurate (TAC) indicating crosslink formation. Significant ductile behavior was observed in the PLA nanocomposites containing 4 pph of nanoclay. Incorporation of nanoclay particles in the PLA matrix stimulated crystal growth as it was studied by differential scanning calorimetry (DSC). The morphology of the nanocomposites characterized by transmission electron microscopy (TEM) and X- ray diffraction (XRD) revealed an exfoliated morphology in the PLA nanocomposite films containing 4 pph of nanoclay. Only very small changes were observed in the chemical structure of the irradiated samples as it was investigated by Fourier transform infrared (FTIR) spectroscopy. Enzymatic degradation rate of PLA and its nanocomposite decreased with increasing crystallinity of the samples. The rate of weight loss was also affected by the morphology of the nanocomposites. (author)

L-(+-Lactic acid production by Lactobacillus rhamnosus B103 from dairy industry waste

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Marcela Piassi Bernardo

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

Bioceramic/Poly (glycolic-poly (lactic acid composite induces mineralized barrier after direct capping of rat tooth pulp tissue

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Alfonso Gala-Garcia

2010-03-01

Full Text Available The aim of this study was to observe the histopathological pulp response following direct pulp capping of mechanically exposed teeth in rats with a composite of beta-tricalcium phosphate-hydroxyapatite bioceramic (BC and poly (glycolic-poly (lactic acid (PLGA material or a calcium hydroxide [Ca(OH2] material, compared to BC alone and a negative control of water. Pulp of the maxillary molars was exposed, followed by capping with the experimental material. The pulpal tissue response was assessed post-operatively at 1, 7, 14 and 30 d, followed by histological analysis. The Ca(OH2 group exhibited severe acute inflammatory cell infiltration at day 14. However after 30 d, a new hard tissue with macro porous obliteration of the pulp chamber and a characteristic necrotic area had appeared. BC and Ca(OH2 capping were associated with moderate inflammation and dentinal bridge similar. Meanwhile, in the BC/PLGA composite group, there was moderate inflammatory infiltrate and formation of a dense and complete dentinal bridge. In conclusion, the BC/PLGA composite material showed a large zone of tertiary dentin, and effectively reorganized the dentin-pulp complex.

Uniaxial drawing and mechanical properties of poly[(R)-3-hydroxybutyrate]/poly(L-lactic acid) blends.

Science.gov (United States)

Park, Jun Wuk; Doi, Yoshiharu; Iwata, Tadahisa

2004-01-01

Blends of poly(L-lactic acid) (PLLA) with two kinds of poly[(R)-3-hydroxybutyrate] (PHB) having different molecular weights, commercial-grade bacterial PHB (bacterial-PHB) and ultrahigh molecular weight PHB (UHMW-PHB), were prepared by the solvent-casting method and uniaxially drawn at two drawing temperatures, around PHB's T(g) (2 degrees C) for PHB-rich blends and around PLLA's T(g) (60 degrees C) for PLLA-rich blends. Differential scanning calorimetry analysis showed that this system was immiscible over the entire composition range. Mechanical properties of all of the samples were improved in proportion to the draw ratio. Although PLLA domains in bacterial-PHB-rich blends remained almost unstretched during cold drawing, a good interfacial adhesion between two polymers and the reinforcing role of PLLA components led to enhanced mechanical properties proportionally to the PLLA content at the same draw ratio. On the contrary, in the case of UHMW-PHB-rich blends, the minor component PLLA was found to be also oriented by cold drawing in ice water due to an increase in the interfacial entanglements caused by the very long chain length of the matrix polymer. As a result, their mechanical properties were considerably improved with increasing PLLA content compared with the bacterial-PHB system. Scanning electron microscopy observations on the surface and cross-section revealed that a layered structure with uniformly oriented microporous in the interior was obtained by selectively removal of PLLA component after simple alkaline treatment.

Micelle-templated, poly(lactic-co-glycolic acid nanoparticles for hydrophobic drug delivery

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Nabar GM

2018-01-01

Full Text Available Gauri M Nabar,1 Kalpesh D Mahajan,1 Mark A Calhoun,2 Anthony D Duong,1 Matthew S Souva,1 Jihong Xu,3,4 Catherine Czeisler,5 Vinay K Puduvalli,3,4 José Javier Otero,5 Barbara E Wyslouzil,1,6 Jessica O Winter1,2 1William G Lowrie Department of Chemical and Biomolecular Engineering, 2Department of Biomedical Engineering, 3Division of Neuro-oncology, College of Medicine, The Ohio State University Comprehensive Cancer Center, 4Dardinger Laboratory for Neuro-oncology and Neurosciences, Department of Neurosurgery, College of Medicine, The Ohio State University Comprehensive Cancer Center, 5Department of Pathology and the Neurological Research Institute, College of Medicine, 6Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA Purpose: Poly(lactic-co-glycolic acid (PLGA is widely used for drug delivery because of its biocompatibility, ability to solubilize a wide variety of drugs, and tunable degradation. However, achieving sub-100 nm nanoparticles (NPs, as might be desired for delivery via the enhanced permeability and retention effect, is extremely difficult via typical top-down emulsion approaches.Methods: Here, we present a bottom-up synthesis method yielding PLGA/block copolymer hybrids (ie, “PolyDots”, consisting of hydrophobic PLGA chains entrapped within self-assembling poly(styrene-b-ethylene oxide (PS-b-PEO micelles.Results: PolyDots exhibit average diameters <50 nm and lower polydispersity than conventional PLGA NPs. Drug encapsulation efficiencies of PolyDots match conventional PLGA NPs (ie, ~30% and are greater than those obtained from PS-b-PEO micelles (ie, ~7%. Increasing the PLGA:PS-b-PEO weight ratio alters the drug release mechanism from chain relaxation to erosion controlled. PolyDots are taken up by model glioma cells via endocytotic mechanisms within 24 hours, providing a potential means for delivery to cytoplasm. PolyDots can be lyophilized with minimal change in morphology and encapsulant

Poly(Lactic-co-Glycolic Acid: Applications and Future Prospects for Periodontal Tissue Regeneration

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Xiaoyu Sun

2017-06-01

Full Text Available Periodontal tissue regeneration is the ultimate goal of the treatment for periodontitis-affected teeth. The success of regenerative modalities relies heavily on the utilization of appropriate biomaterials with specific properties. Poly (lactic-co-glycolic acid (PLGA, a synthetic aliphatic polyester, has been actively investigated for periodontal therapy due to its favorable mechanical properties, tunable degradation rates, and high biocompatibility. Despite the attractive characteristics, certain constraints associated with PLGA, in terms of its hydrophobicity and limited bioactivity, have led to the introduction of modification strategies that aimed to improve the biological performance of the polymer. Here, we summarize the features of the polymer and update views on progress of its applications as barrier membranes, bone grafts, and drug delivery carriers, which indicate that PLGA can be a good candidate material in the field of periodontal regenerative medicine.

Femtosecond laser irradiation of the fluorescent molecules-loaded poly(lactic-co-glycolic acid)

Science.gov (United States)

Umemoto, Taiga; Shibata, Akimichi; Terakawa, Mitsuhiro

2017-09-01

Molecular release from scaffolds is desired for tailoring cell-compatible tissue engineering. Several methods have been proposed to control molecular release, such as annealing, plasma treatment, and laser processing. In this study, we describe the alteration of Rhodamine B (RhB)-loaded poly(lactic-co-glycolic acid) (PLGA) after femtosecond laser irradiation, which was evaluated on the basis of the water absorption and mass remaining. Fluorescence measurement of released RhB molecules revealed the acceleration of the molecular release upon 400-nm laser irradiation, whereas 800-nm laser irradiation did not induce a comparable degree of change compared with non-irradiated samples. The result of the water absorption measurement indicates that the large amount of water absorption of 400-nm laser-irradiated PLGA sample may accelerate the diffusion of the loaded molecules through absorbing water, which resulted in the faster molecular release.

Microfluidics for producing poly (lactic-co-glycolic acid)-based pharmaceutical nanoparticles.

Science.gov (United States)

Li, Xuanyu; Jiang, Xingyu

2017-12-24

Microfluidic chips allow the rapid production of a library of nanoparticles (NPs) with distinct properties by changing the precursors and the flow rates, significantly decreasing the time for screening optimal formulation as carriers for drug delivery compared to conventional methods. The batch-to-batch reproducibility which is essential for clinical translation is achieved by precisely controlling the precursors and the flow rate, regardless of operators. Poly (lactic-co-glycolic acid) (PLGA) is the most widely used Food and Drug Administration (FDA)-approved biodegradable polymers. Researchers often combine PLGA with lipids or amphiphilic molecules to assemble into a core/shell structure to exploit the potential of PLGA-based NPs as powerful carriers for cancer-related drug delivery. In this review, we discuss the advantages associated with microfluidic chips for producing PLGA-based functional nanocomplexes for drug delivery. These laboratory-based methods can readily scale up to provide sufficient amount of PLGA-based NPs in microfluidic chips for clinical studies and industrial-scale production. Copyright © 2017. Published by Elsevier B.V.

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

Science.gov (United States)

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

2015-04-01

This study presents a facile synthesis of biomimetic hydroxyapatite nanorod/poly(D,L) lactic acid (HAp/PDLLA) scaffolds with the use of solvent casting combined with a salt-leaching technique for bone-tissue engineering. Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy were used to observe the morphologies, pore structures of synthesized scaffolds, interactions between hydroxyapatite nanorods and poly(D,L) lactic acid, as well as the compositions of the scaffolds, respectively. Porosity of the scaffolds was determined using the liquid substitution method. Moreover, the apatite-forming capability of the scaffolds was evaluated through simulated body fluid (SBF) incubation tests, whereas the viability, attachment, and distribution of human osteoblast cells (MG 63 cell line) on the scaffolds were determined through alamarBlue assay and confocal laser microscopy after nuclear staining with 4',6-diamidino-2-phenylindole and actin filaments of a cytoskeleton with Oregon Green 488 phalloidin. Results showed that hydroxyapatite nanorod/poly(D,L) lactic acid scaffolds that mimic the structure of natural bone were successfully produced. These scaffolds possessed macropore networks with high porosity (80-84%) and mean pore sizes ranging 117-183 μm. These scaffolds demonstrated excellent apatite-forming capabilities. The rapid formation of bone-like apatites with flower-like morphology was observed after 7 days of incubation in SBFs. The scaffolds that had a high percentage (30 wt.%) of hydroxyapatite demonstrated better cell adhesion, proliferation, and distribution than those with low percentages of hydroxyapatite as the days of culture increased. This work presented an efficient route for developing biomimetic composite scaffolds, which have potential applications in bone-tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Biodegradability Study of the Blend Film of High Density Polyethylene and Poly(lactic acid Disposable Packages Flake

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Elahe Baghi Neirizi

2016-03-01

Full Text Available One of the major concerns of using a non-biodegradable polymer product is its disposal at the end of its life cycle. Development of biodegradable plastics promises an alternative solution to combat this problem. Blending of poly(lactic acid with non-biodegradable polymers is a practical and economical method for modifying the biodegradability properties of non-biodegradable polymers. In this study, soil biodegradability of the blends of high density polyethylene (HDPE and variable amounts of recycled poly(lactic acid (r-PLA plastic flakes at 0, 5, 10, 20, 30, 40 and 50 wt% was studied. The behavior of the force-elongation profile of the blends having r-PLA content of lower than 30 wt% was approximately the same as that of pure HDPE while, it was completely different for the other blends. Tearing force and elongation-at-yield-point of the blends films with the 20 to 50 wt% r-PLA were decreased significantly after 60 days of soil biodegradability test. Morphological study showed that biodegradability of the blend films at surface of the samples (deep pores and grooves was increased with extended biodegradability time and higher r-PLA content, while, this variation was significant for the blend films of more than 20 wt% r-PLA content. Thermal properties evaluation by differential scanning calorimetry (DSC curves indicated that the glass transition temperature and enthalpy peaks during the heating stage were eliminated with increasing the biodegradability testing time. Also, reduction in the crystallinity degree of the r-PLA component with increasing the biodegradability testing time coincided with the earlier results.

Selective Depolymerization and Effects of Homolysis of Poly(L-lactic acid) in a Blend with Polypropylene

International Nuclear Information System (INIS)

Nishida, H.; Tsukegi, T.; Shirai, Y.; Arazoe, Y.; Yan, W.; Shirai, Y.

2009-01-01

Blends of poly(L-lactic acid) (PLLA) and polypropylene (PP), which are candidates for the practical use of PLLA, were investigated for selective degradation of PLLA, resulting in quantitative conversion of PLLA components into cyclic monomers, lactide, using magnesium oxide (Mg O) as a depolymerization catalyst. Obviously, the catalyst Mg O selectively accelerated only the PLLA depolymerization in the blends, dominantly generating L,L-lactide as a volatile product and separating the PP component. Expected effects of homolysis in the blend system were also determined as slight changes in activation energy of degradation for both the components and through the suppression of degradation by an antioxidant.

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

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

2016-01-01

Lactic acid, which can be obtained through fermentation, is an interesting compound because it can be utilized in different fields, such as in the food, pharmaceutical and chemical industries as a bio-based molecule for bio-refinery. In addition, lactic acid has recently gained more interest due to the possibility of manufacturing poly(lactic acid), a green polymer that can replace petroleum-derived plastics and be applied in medicine for the regeneration of tissues and in sutures, repairs and implants. One of the great advantages of fermentation is the possibility of using agribusiness wastes to obtain optically pure lactic acid. The conventional batch process of fermentation has some disadvantages such as inhibition by the substrate or the final product. To avoid these problems, this study was focused on improving the production of lactic acid through different feeding strategies using whey, a residue of agribusiness. The downstream process is a significant bottleneck because cost-effective methods of producing high-purity lactic acid are lacking. Thus, the investigation of different methods for the purification of lactic acid was one of the aims of this work. The pH-stat strategy showed the maximum production of lactic acid of 143.7g/L. Following purification of the lactic acid sample, recovery of reducing sugars and protein and color removal were 0.28%, 100% and 100%, respectively. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

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

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Al-Mulla, E.M.A.

2011-01-01

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)

Two-step modification of poly(D, L-lactic acid) by ethylenediamine-maleic anhydride

International Nuclear Information System (INIS)

Cao Chengbo; Zhu Fanglian; Yu Xueli; Wang Qin; Wang Chuandong; Li Baolu; Lv Ronghui; Li Musen

2008-01-01

Poly(lactic acid) (PLA) was modified by maleic anhydride (MAH), then the resultant MAH modified PLA (MPLA) was acylated with ethylenediamine (EDA), so EDA-MAH modified PLA (EMPLA) was prepared. The results of DSC, FT-IR and NMR testified that MAH and EAD were successfully introduced into the original polymer. The hydrophilicity of EMPLA was considerably increased compared with that of PLA. The degradation experiment showed that the introduction of EDA into the original polymer could neutralize the carboxyl end groups of the degradation products. The results of SEM and MTT of rat osteoblasts cultured in vitro showed that the cytocompatibility and cell adhesion of the modified materials were significantly increased compared with the original polymer, especially EMPLA; the number of cells were obviously increased and cells attached firmly to the material; these were ascribed to the EDA neutralizing the carboxyl end groups of the degradation products

In vitro evaluation of chitosan/poly(lactic acid-glycolic acid) sintered microsphere scaffolds for bone tissue engineering.

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Jiang, Tao; Abdel-Fattah, Wafa I; Laurencin, Cato T

2006-10-01

A three-dimensional (3-D) scaffold is one of the major components in many tissue engineering approaches. We developed novel 3-D chitosan/poly(lactic acid-glycolic acid) (PLAGA) composite porous scaffolds by sintering together composite chitosan/PLAGA microspheres for bone tissue engineering applications. Pore sizes, pore volume, and mechanical properties of the scaffolds can be manipulated by controlling fabrication parameters, including sintering temperature and sintering time. The sintered microsphere scaffolds had a total pore volume between 28% and 37% with median pore size in the range 170-200microm. The compressive modulus and compressive strength of the scaffolds are in the range of trabecular bone making them suitable as scaffolds for load-bearing bone tissue engineering. In addition, MC3T3-E1 osteoblast-like cells proliferated well on the composite scaffolds as compared to PLAGA scaffolds. It was also shown that the presence of chitosan on microsphere surfaces increased the alkaline phosphatase activity of the cells cultured on the composite scaffolds and up-regulated gene expression of alkaline phosphatase, osteopontin, and bone sialoprotein.

Biodegradable poly (lactic acid-co-glycolic acid scaffolds as carriers for genetically-modified fibroblasts.

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Tatjana Perisic

Full Text Available Recent advances in gene delivery into cells allow improved therapeutic effects in gene therapy trials. To increase the bioavailability of applied cells, it is of great interest that transfected cells remain at the application site and systemic spread is minimized. In this study, we tested clinically used biodegradable poly(lactic acid-co-glycolic acid (PLGA scaffolds (Vicryl & Ethisorb as transient carriers for genetically modified cells. To this aim, we used human fibroblasts and examined attachment and proliferation of untransfected cells on the scaffolds in vitro, as well as the mechanical properties of the scaffolds at four time points (1, 3, 6 and 9 days of cultivation. Furthermore, the adherence of cells transfected with green fluorescent protein (GFP and vascular endothelial growth factor (VEGF165 and also VEGF165 protein secretion were investigated. Our results show that human fibroblasts adhere on both types of PLGA scaffolds. However, proliferation and transgene expression capacity were higher on Ethisorb scaffolds most probably due to a different architecture of the scaffold. Additionally, cultivation of the cells on the scaffolds did not alter their biomechanical properties. The results of this investigation could be potentially exploited in therapeutic regiments with areal delivery of transiently transfected cells and may open the way for a variety of applications of cell-based gene therapy, tissue engineering and regenerative medicine.

Cocrystallization as a tool to solve deliquescence issues: The case of L-lactic acid

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de Maere d'Aertrycke, J. B.; Robeyns, K.; Willocq, J.; Leyssens, T.

2017-08-01

L-Lactic acid is an organic acid used in various fields such as food, cosmetic or pharmaceutical industry. It furthermore is the building-block of poly-lactic acid, a biodegradable and bioavailable polymer. Still, handling L-lactic acid under its solid form remains less straightforward mainly due to its deliquescent behavior, a phase transition from the solid to the dissolved state resulting from air humidity absorption. If several techniques are already known to avoid or reduce deliquescence, the use of cocrystallization in this context is still poorly investigated. In this paper, we investigate whether cocrystallization can be used as a suitable solution for deliquescence in the case of L-lactic acid. Out of 32 possible coformers tested, four were found to form cocrystals with L-lactic acid and the crystal structures of 1:1 L-lactic acid:D-tryptophan and 1:1 L-lactic acid:3-nitrobenzamide were determined. The hygroscopic behavior of these latter two was studied and compared to the behavior of pure L-lactic acid. Significant improvement was observed: dynamic vapor sorption at 25 °C revealed that water absorbed at 90% relative humidity dropped from 1.3157 g/gsample to 0.0017 g/gsample or 0.0299 g/gsample, with cocrystals of D-tryptophan and 3-nitrobenzamide respectively. This illustrates the effectiveness of cocrystallization as a tool to treat deliquescent materials.

Lactic acid test

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... this page: //medlineplus.gov/ency/article/003507.htm Lactic acid test To use the sharing features on this page, please enable JavaScript. Lactic acid is mainly produced in muscle cells and red ...

Biological Evaluation of Flexible Polyurethane/Poly l-Lactic Acid Composite Scaffold as a Potential Filler for Bone Regeneration

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Yuk Fai Lui

2017-09-01

Full Text Available Degradable bone graft substitute for large-volume bone defects is a continuously developing field in orthopedics. With the advance in biomaterial in past decades, a wide range of new materials has been investigated for their potential in this application. When compared to common biopolymers within the field such as PLA or PCL, elastomers such as polyurethane offer some unique advantages in terms of flexibility. In cases of bone defect treatments, a flexible soft filler can help to establish an intimate contact with surrounding bones to provide a stable bone-material interface for cell proliferation and ingrowth of tissue. In this study, a porous filler based on segmented polyurethane incorporated with poly l-lactic acid was synthesized by a phase inverse salt leaching method. The filler was put through in vitro and in vivo tests to evaluate its potential in acting as a bone graft substitute for critical-sized bone defects. In vitro results indicated there was a major improvement in biological response, including cell attachment, proliferation and alkaline phosphatase expression for osteoblast-like cells when seeded on the composite material compared to unmodified polyurethane. In vivo evaluation on a critical-sized defect model of New Zealand White (NZW rabbit indicated there was bone ingrowth along the defect area with the introduction of the new filler. A tight interface formed between bone and filler, with osteogenic cells proliferating on the surface. The result suggested polyurethane/poly l-lactic acid composite is a material with the potential to act as a bone graft substitute for orthopedics application.

A comprehensive study on the fabrication and properties of biocomposites of poly(lactic acid)/ceramics for bone tissue engineering.

Science.gov (United States)

Tajbakhsh, Saeid; Hajiali, Faezeh

2017-01-01

The fabrication of a suitable scaffold material is one of the major challenges for bone tissue engineering. Poly(lactic acid) (PLA) is one of the most favorable matrix materials in bone tissue engineering owing to its biocompatibility and biodegradability. However, PLA suffers from some shortcomings including low degradation rate, low cell adhesion caused by its hydrophobic property, and inflammatory reactions in vivo due to its degradation product, lactic acid. Therefore, the incorporation of bioactive reinforcements is considered as a powerful method to improve the properties of PLA. This review presents a comprehensive study on recent advances in the synthesis of PLA-based biocomposites containing ceramic reinforcements, including various methods of production and the evaluation of the scaffolds in terms of porosity, mechanical properties, in vitro and in vivo biocompatibility and bioactivity for bone tissue engineering applications. The production routes range from traditional approaches such as the use of porogens to provide porosity in the scaffolds to novel methods such as solid free-form techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct observation of shear piezoelectricity in poly-l-lactic acid nanowires

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Michael Smith

2017-07-01

Full Text Available Piezoelectric polymers are capable of interconverting mechanical and electrical energy, and are therefore candidate materials for biomedical applications such as sensors, actuators, and energy harvesters. In particular, nanowires of these materials are attractive as they can be unclamped, flexible and sensitive to small vibrations. Poly-l-lactic acid (PLLA nanowires have been investigated for their use in biological applications, but their piezoelectric properties have never been fully characterised, even though macroscopic films and fibres have been shown to exhibit shear piezoelectricity. This piezoelectric mode is particularly interesting for in vivo applications where shear forces are especially relevant, and is similar to what has been observed in natural materials such as bone and DNA. Here, using piezo-response force microscopy (PFM, we report the first direct observation of shear piezoelectricity in highly crystalline and oriented PLLA nanowires grown by a novel template-wetting method. Our results are validated using finite-element simulations and numerical analysis, which importantly and more generally allow for accurate interpretation of PFM signals in soft nanostructured materials. Our work opens up the possibility for the development of biocompatible and sustainable piezoelectric nanogenerators and sensors based on polymer nanowires.

Preparation, Cell Compatibility and Degradability of Collagen-Modified Poly(lactic acid

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Miaomiao Cui

2015-01-01

Full Text Available Poly(lactic acid (PLA was modified using collagen through a grafting method to improve its biocompatibility and degradability. The carboxylic group at the open end of PLA was transferred into the reactive acylchlorided group by a reaction with phosphorus pentachloride. Then, collagen-modified PLA (collagen-PLA was prepared by the reaction between the reactive acylchlorided group and amino/hydroxyl groups on collagen. Subsequently, the structure of collagen-PLA was confirmed by Fourier transform infrared spectroscopy, fluorescein isothiocyanate-labeled fluorescence spectroscopy, X-ray photoelectron spectroscopy, and DSC analyses. Finally, some properties of collagen-PLA, such as hydrophilicity, cell compatibility and degradability were characterized. Results showed that collagen had been grafted onto the PLA with 5% graft ratio. Water contact angle and water absorption behavior tests indicated that the hydrophilicity of collagen-PLA was significantly higher than that of PLA. The cell compatibility of collagen-PLA with mouse embryonic fibroblasts (3T3 was also significantly better than PLA in terms of cell morphology and cell proliferation, and the degradability of PLA was also improved after introducing collagen. Results suggested that collagen-PLA was a promising candidate for biomedical applications.

Direct observation of shear piezoelectricity in poly-l-lactic acid nanowires

Science.gov (United States)

Smith, Michael; Calahorra, Yonatan; Jing, Qingshen; Kar-Narayan, Sohini

2017-07-01

Piezoelectric polymers are capable of interconverting mechanical and electrical energy, and are therefore candidate materials for biomedical applications such as sensors, actuators, and energy harvesters. In particular, nanowires of these materials are attractive as they can be unclamped, flexible and sensitive to small vibrations. Poly-l-lactic acid (PLLA) nanowires have been investigated for their use in biological applications, but their piezoelectric properties have never been fully characterised, even though macroscopic films and fibres have been shown to exhibit shear piezoelectricity. This piezoelectric mode is particularly interesting for in vivo applications where shear forces are especially relevant, and is similar to what has been observed in natural materials such as bone and DNA. Here, using piezo-response force microscopy (PFM), we report the first direct observation of shear piezoelectricity in highly crystalline and oriented PLLA nanowires grown by a novel template-wetting method. Our results are validated using finite-element simulations and numerical analysis, which importantly and more generally allow for accurate interpretation of PFM signals in soft nanostructured materials. Our work opens up the possibility for the development of biocompatible and sustainable piezoelectric nanogenerators and sensors based on polymer nanowires.

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

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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.

Antioxidant poly(lactic-co-glycolic) acid nanoparticles made with α-tocopherol-ascorbic acid surfactant.

Science.gov (United States)

Astete, Carlos E; Dolliver, Debra; Whaley, Meocha; Khachatryan, Lavrent; Sabliov, Cristina M

2011-12-27

The goal of the study was to synthesize a surfactant made of α-tocopherol (vitamin E) and ascorbic acid (vitamin C) of antioxidant properties dubbed as EC, and to use this surfactant to make poly(lactic-co-glycolic) acid (PLGA) nanoparticles. Self-assembled EC nanostructures and PLGA-EC nanoparticles were made by nanoprecipitation, and their physical properties (size, size distribution, morphology) were studied at different salt concentrations, surfactant concentrations, and polymer/surfactant ratios. EC surfactant was shown to form self-assembled nanostructures in water with a size of 22 to 138 nm in the presence of sodium chloride, or 12 to 31 nm when synthesis was carried out in sodium bicarbonate. Polymeric PLGA-EC nanoparticles presented a size of 90 to 126 nm for 40% to 120% mass ratio PLGA to surfactant. For the same mass ratios, the PLGA-Span80 formed particles measured 155 to 216 nm. Span80 formed bilayers, whereas EC formed monolayers at the interfaces. PLGA-EC nanoparticles and EC showed antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay measurements using UV and EPR techniques, antioxidant activity which is not characteristic to commercially available Span80. The thiobarbituric acid reactive substances (TBARS) assay for lipid peroxidation showed that PLGA nanoparticles with EC performed better as antioxidants than the EC nanoassembly or the free vitamin C. Nanoparticles were readily internalized by HepG2 cells and were localized in the cytoplasm. The newly synthesized EC surfactant was therefore found successful in forming uniform, small size polymeric nanoparticles of intrinsic antioxidant properties.

Poly(lactic-co-glycolic) acid drug delivery systems through transdermal pathway: an overview.

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Naves, Lucas; Dhand, Chetna; Almeida, Luis; Rajamani, Lakshminarayanan; Ramakrishna, Seeram; Soares, Graça

2017-05-01

In past few decades, scientists have made tremendous advancement in the field of drug delivery systems (DDS), through transdermal pathway, as the skin represents a ready and large surface area for delivering drugs. Efforts are in progress to design efficient transdermal DDS that support sustained drug release at the targeted area for longer duration in the recommended therapeutic window without producing side-effects. Poly(lactic-co-glycolic acid) (PLGA) is one of the most promising Food and Drug Administration approved synthetic polymers in designing versatile drug delivery carriers for different drug administration routes, including transdermal drug delivery. The present review provides a brief introduction over the transdermal drug delivery and PLGA as a material in context to its role in designing drug delivery vehicles. Attempts are made to compile literatures over PLGA-based drug delivery vehicles, including microneedles, nanoparticles, and nanofibers and their role in transdermal drug delivery of different therapeutic agents. Different nanostructure evaluation techniques with their working principles are briefly explained.

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

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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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrophobic silica nanoparticles as reinforcing filler for poly (lactic acid polymer matrix

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Pilić Branka M.

2016-01-01

Full Text Available Properties of poly (lactic acid (PLA and its nanocomposites, with silica nanoparticles (SiO2, as filler were investigated. Neat PLA films and PLA films with different percentage of hydrophobic fumed silica nanoparticles (0.2, 0.5, 1, 2, 3 and 5 wt. % were prepared by solution casting method. Several tools were used to characterize the influence of different silica content on crystalline behavior, and thermal, mechanical and barrier properties of PLA/SiO2 nanocomposites. Results from scanning electron microscope (SEM showed that the nanocomposite preparation and selection of specific hydrophobic spherical nano filler provide a good dispersion of the silica nanoparticles in the PLA matrix. Addition of silica nanoparticles improved mechanical properties, the most significant improvement being observed for lowest silica content (0.2wt.%. Barrier properties were improved for all measured gases at all loadings of silica nanoparticles. The degree of crystallinity for PLA slightly increased by adding 0.2 and 0.5 wt. % of nano filler. [Projekat Ministarstva nauke Republike Srbije, br. III46001

Preparation of hydroxyapatite/poly(lactic acid) hybrid microparticles for local drug delivery

International Nuclear Information System (INIS)

Loca, D; Locs, J; Berzina-Cimdina, L

2013-01-01

Calcium phosphate (CaP) bioceramic is well known as bioactive and biocompatible material in bone tissue regeneration applications. Apatitic CaP, especially nano sized hydroxyapatite (NHAp), is more similar to the natural apatite presented in the bone tissue than CaP bioceramics. In the current research NHAp was modified using biodegradable polymer – poly(lactic acid) (PLA) to develop composites providing bone regeneration and local drug delivery. NHAp/PLA microcapsules were prepared using solid-in-water-in-oil-in-water (s/w 1 /o/w 2 ) encapsulation technology. The impact of primary and secondary emulsion stability on the emulsion droplet and microparticle properties was evaluated. The stability of final emulsion can be increased by varying the process parameters. Stable s/w 1 /o/w 2 emulsion using 3ml of NHAp suspension, not less than 100ml of 4% PVA water solution and 10ml of 10% PLA solution in dichloromethane can be obtained. S/w 1 /o/w 2 microencapuslation method can be effectively used for the preparation of multi-domain microcapsules achieving high NHAp encapsulation efficacy (93%)

Radiation-induced crosslinking and post-processing of poly(L-lactic acid) composite

International Nuclear Information System (INIS)

Nagasawa, Naotsugu; Kasai, Noboru; Yagi, Toshiaki; Yoshii, Fumio; Tamada, Masao

2011-01-01

Poly(L-lactic acid), PLLA, was irradiated using electron beams (EBs) in the presence of triallyl isocyanurate (TAIC) at 5% concentration as crosslinking agent. The crosslinked PLLA obtained has heat resistance, as demonstrated by retention of its original shape at glass transition temperature or even higher than 200 o C. As an application of this fact, crosslinked PLLA is applied in spectacle lens to prevent shape deformation of eyeglass frames in displaying and transporting. However, in this application to lens, it is not enough to improve the thermal deformation of PLLA under stress at 70 o C. Radiation-induced crosslinking of a PLLA/silicon dioxide (SiO 2 ) composite with TAIC and post-processing of the crosslinked PLLA composite by heating were further investigated from the viewpoint of thermal deformation. The PLLA materials have several advantages such as high heat resistance and transparency. It is therefore proved that the combination of radiation-induced crosslinking, composition of SiO 2 and post-heating is beneficial for expanding the applications of PLLA.

Radiation-induced crosslinking and post-processing of poly(L-lactic acid) composite

Energy Technology Data Exchange (ETDEWEB)

Nagasawa, Naotsugu, E-mail: nagasawa.naotsugu@jaea.go.j [Japan Atomic Energy Agency (JAEA), Quantum Beam Science Directorate, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Kasai, Noboru; Yagi, Toshiaki; Yoshii, Fumio; Tamada, Masao [Japan Atomic Energy Agency (JAEA), Quantum Beam Science Directorate, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

2011-02-15

Poly(L-lactic acid), PLLA, was irradiated using electron beams (EBs) in the presence of triallyl isocyanurate (TAIC) at 5% concentration as crosslinking agent. The crosslinked PLLA obtained has heat resistance, as demonstrated by retention of its original shape at glass transition temperature or even higher than 200 {sup o}C. As an application of this fact, crosslinked PLLA is applied in spectacle lens to prevent shape deformation of eyeglass frames in displaying and transporting. However, in this application to lens, it is not enough to improve the thermal deformation of PLLA under stress at 70 {sup o}C. Radiation-induced crosslinking of a PLLA/silicon dioxide (SiO{sub 2}) composite with TAIC and post-processing of the crosslinked PLLA composite by heating were further investigated from the viewpoint of thermal deformation. The PLLA materials have several advantages such as high heat resistance and transparency. It is therefore proved that the combination of radiation-induced crosslinking, composition of SiO{sub 2} and post-heating is beneficial for expanding the applications of PLLA.

Plasticization of poly(lactic acid) using different molecular weight of Poly(ethylene glycol)

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Septevani, Athanasia Amanda; Bhakri, Samsul

2017-11-01

Poly (lactic acid) (PLA) has been known as an excellent candidate for developing the future bioplastic due to its biodegradability and competitive price. However, inherent brittleness and low thermal stability of PLA have limited its applications. Considerable studies have been developed to improve the flexibility of PLA, in which blending PLA with various plasticizers has been identified as a cost-effective way to lower glass-transition temperature (Tg) and thus improve its elongation property. In this study, PLA was modified by incorporating poly(ethylene glycol) as a plasticizer with different molecular weights (M¯w 400, 1000, and 6000, called respectively as PEG 400, PEG 1000, and PEG 6000) via a solvent-casting blend method. FTIR was used for analyzing the chemical interaction while TGA and DSC measured the thermal behavior of PLA/PEG. The results indicated that the addition of lower M¯w (PEG 400 and PEG 1000) could reduce the Tg due to the enhancement of chain mobility of PLA with PEG and so driving into a more amorphous states resulted reduction of melting temperature (Tm) compared to the neat PLA. Further, at a higher M¯w of PEG 6000, the longer chain of ethylene glycol, in contrast, resulted a gradual increase in the Tg as well as Tm where the value went back to the point of neat PLA compared to the other lower molecular weight of PLA. This was due to the decrease in polymer miscibility with the increasing of M¯w. In terms of thermal stability, the addition of PEG exhibited two step degradation behavior while the neat PLA only possessed single step degradation. The presence of PEG could act as a protective barrier layer that could hinder the permeability of the volatile compound and product during decomposition reaction and thus could eventually delay and slower the degradation process. It was observed that the addition of PEG at higher M¯w (PEG1000 and PEG 6000) exhibited a higher second degradation temperature up to 380 °C.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Shao, Weili [Key Laboratory of Advanced Textile Composites (Ministry of Education), Institute of Textile Composites, Tianjin Polytechnic University, Tianjin 300387 (China); Henan Provincial Key Laboratory of Functional Textile Materials, Zhongyuan University of Technology, Zhengzhou 450007 (China); He, Jianxin, E-mail: hejianxin771117@163.com [Henan Provincial Key Laboratory of Functional Textile Materials, Zhongyuan University of Technology, Zhengzhou 450007 (China); Sang, Feng [Department of Acquired Immune Deficiency Syndrome Treatment and Research Center, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou 450000 (China); Wang, Qian [Henan Provincial Key Laboratory of Functional Textile Materials, Zhongyuan University of Technology, Zhengzhou 450007 (China); Chen, Li [Key Laboratory of Advanced Textile Composites (Ministry of Education), Institute of Textile Composites, Tianjin Polytechnic University, Tianjin 300387 (China); Cui, Shizhong [Key Laboratory of Advanced Textile Composites (Ministry of Education), Institute of Textile Composites, Tianjin Polytechnic University, Tianjin 300387 (China); Henan Provincial Key Laboratory of Functional Textile Materials, Zhongyuan University of Technology, Zhengzhou 450007 (China); Ding, Bin [Henan Provincial Key Laboratory of Functional Textile Materials, Zhongyuan University of Technology, Zhengzhou 450007 (China); State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201600 (China)

2016-05-01

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

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

International Nuclear Information System (INIS)

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

2013-01-01

The large amount of waste that is discharged along with the diffusion of poly(L-lactic acid) (PLLA) articles in use is persistent concern. Previously, we studied solid-phase denitrification (SPD) processes using PLLA to establish an effective re-use of PLLA waste. We found that PLLA with a weight-average molecular weight (M w ) of approximately 10,000 was suitable for SPD processes; however, the recycling of PLLA waste consumes a high energy. A new PLLA plastic including 5% poly(ethylene oxalate) (PEOxPLLA) as a blend material has attracted attention because recycling of PEOxPLLA consumes less electricity than that of PLLA. In this study, our main objectives were to evaluate whether PEOxPLLA can be used for SPD processes by changing its M w and to investigate the bioavailability for denitrification of hydrolysates released from PEOxPLLA. The predicted hydrolysates, including oxalic acid, ethylene glycol, and lactate, are abiotically released, leading to different biological nitrate removal rates. Consequently, the nitrate removal rate of PEOxPLLA ranged from 0.9–4.1 mg-NO 3 − -N·g-MLSS·h −1 by changing the M w in the range of 8,500–238,000. In culture-dependent approaches, denitrifying bacteria using each substrate as an electron donor are found in activated sludge, suggesting that all hydrolysates functioned in the SPD processes using PEOxPLLA.

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

2014-08-22

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.

Environmentally Friendly Compatibilizers from Soybean Oil for Ternary Blends of Poly(lactic acid-PLA, Poly(ε-caprolactone-PCL and Poly(3-hydroxybutyrate-PHB

Directory of Open Access Journals (Sweden)

María Jesús Garcia-Campo

2017-11-01

Full Text Available Ternary blends of poly(lactic acid (PLA, poly(3-hydroxybutyrate (PHB and poly(ε-caprolactone (PCL with a constant weight percentage of 60%, 10% and 30% respectively were compatibilized with soybean oil derivatives epoxidized soybean oil (ESO, maleinized soybean oil (MSO and acrylated epoxidized soybean oil (AESO. The potential compatibilization effects of the soybean oil-derivatives was characterized in terms of mechanical, thermal and thermomechanical properties. The effects on morphology were studied by field emission scanning electron microscopy (FESEM. All three soybean oil-based compatibilizers led to a noticeable increase in toughness with a remarkable improvement in elongation at break. On the other hand, both the tensile modulus and strength decreased, but in a lower extent to a typical plasticization effect. Although phase separation occurred, all three soybean oil derivatives led somewhat to compatibilization through reaction between terminal hydroxyl groups in all three biopolyesters (PLA, PHB and PCL and the readily reactive groups in the soybean oil derivatives, that is, epoxy, maleic anhydride and acrylic/epoxy functionalities. In particular, the addition of 5 parts per hundred parts of the blend (phr of ESO gave the maximum elongation at break while the same amount of MSO and AESO gave the maximum toughness, measured through Charpy’s impact tests. In general, the herein-developed materials widen the potential of ternary PLA formulations by a cost effective blending method with PHB and PCL and compatibilization with vegetable oil-based additives.

Environmentally Friendly Compatibilizers from Soybean Oil for Ternary Blends of Poly(lactic acid)-PLA, Poly(ε-caprolactone)-PCL and Poly(3-hydroxybutyrate)-PHB.

Science.gov (United States)

Garcia-Campo, María Jesús; Quiles-Carrillo, Luis; Masia, Jaime; Reig-Pérez, Miguel Jorge; Montanes, Nestor; Balart, Rafael

2017-11-22

Ternary blends of poly(lactic acid) (PLA), poly(3-hydroxybutyrate) (PHB) and poly(ε-caprolactone) (PCL) with a constant weight percentage of 60%, 10% and 30% respectively were compatibilized with soybean oil derivatives epoxidized soybean oil (ESO), maleinized soybean oil (MSO) and acrylated epoxidized soybean oil (AESO). The potential compatibilization effects of the soybean oil-derivatives was characterized in terms of mechanical, thermal and thermomechanical properties. The effects on morphology were studied by field emission scanning electron microscopy (FESEM). All three soybean oil-based compatibilizers led to a noticeable increase in toughness with a remarkable improvement in elongation at break. On the other hand, both the tensile modulus and strength decreased, but in a lower extent to a typical plasticization effect. Although phase separation occurred, all three soybean oil derivatives led somewhat to compatibilization through reaction between terminal hydroxyl groups in all three biopolyesters (PLA, PHB and PCL) and the readily reactive groups in the soybean oil derivatives, that is, epoxy, maleic anhydride and acrylic/epoxy functionalities. In particular, the addition of 5 parts per hundred parts of the blend (phr) of ESO gave the maximum elongation at break while the same amount of MSO and AESO gave the maximum toughness, measured through Charpy's impact tests. In general, the herein-developed materials widen the potential of ternary PLA formulations by a cost effective blending method with PHB and PCL and compatibilization with vegetable oil-based additives.

Mechanical performance evaluation of bionanocomposites with polymeric matrix of poly(lactic acid)-PLA and organo clay

International Nuclear Information System (INIS)

Cavalcanti, Shirley N.; Melo, Tomas J.A. de; Araujo, Edcleide M.; Oliveira, Akidauana D.A.; Lima, Jessica C.C.

2011-01-01

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)

Influence of polymer swelling and dissolution into food simulants on the release of graphene nanoplates and carbon nanotubes from poly(lactic) acid and polypropylene composite films

OpenAIRE

Velichkova, Hristiana; Petrova, Ivanka; Kotsilkov, Stanislav; Ivanov, Evgeni; Vitanov, Nikolay K.; Kotsilkova, Rumiana

2017-01-01

The study compared the effects of swelling and dissolution of a matrix polymer by food simulants on the release of graphene nanoplates (GNPs) and multiwall carbon nanotubes (MWCNTs) from poly(lactic) acid (PLA) and polypropylene (PP) composite films. The total migration was determined gravimetrically in the ethanol and acetic acid food simulants at different time and temperature conditions, while migrants were detected by laser diffraction analysis and transmission electron microscopy. Swelli...

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)

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

2015-01-01

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

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Opportunities, perspectives and limits in lactic acid production from waste and industrial by-products

Directory of Open Access Journals (Sweden)

Mladenović Dragana D.

2016-01-01

Full Text Available In line with the goals of sustainable development and environmental protection today great attention is directed towards new technologies for waste and industrial by-products utilization. Waste products represent potentially good raw material for production other valuable products, such as bioethanol, biogas, biodiesel, organic acids, enzymes, microbial biomass, etc. Since the first industrial production to the present, lactic acid has found wide application in food, cosmetic, pharmaceutical and chemical industries. In recent years, the demand for lactic acid has been increasing considerably owing to its potential use as a monomer for the production of poly-lactic acid (PLA polymers which are biodegradable and biocompatible with wide applications. Waste and industrial by-products such are whey, molasses, stillage, waste starch and lignocellulosic materials are a good source of fermentable sugars and many other substances of great importance for the growth of microorganisms, such as proteins, minerals and vitamins. Utilization of waste products for production of lactic acid could help to reduce the total cost of lactic acid production and except the economic viability of the process offers a solution of their disposal. Fermentation process depends on chemical and physical nature of feedstocks and the lactic acid producer. This review describes the characteristics, abilities and limits of microorganisms involved in lactic acid production, as well as the characteristics and types of waste products for lactic acid production. The fermentation methods that have been recently reported to improve lactic acid production are summarized and compared. In order to improve processes and productivity, fed-batch fermentation, fermentation with immobilized cell systems and mixed cultures and opportunities of open (non-sterilized fermentation have been investigated.

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.

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.

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.

Antibacterial efficacy of triple-layered poly(lactic-co-glycolic acid)/nanoapatite/lauric acid guided bone regeneration membrane on periodontal bacteria.

Science.gov (United States)

Saarani, Nur Najiha; Jamuna-Thevi, Kalitheerta; Shahab, Neelam; Hermawan, Hendra; Saidin, Syafiqah

2017-05-31

A guided bone regeneration (GBR) membrane has been extensively used in the repair and regeneration of damaged periodontal tissues. One of the main challenges of GBR restoration is bacterial colonization on the membrane, constitutes to premature membrane degradation. Therefore, the purpose of this study was to investigate the antibacterial efficacy of triple-layered GBR membrane composed of poly(lactic-co-glycolic acid) (PLGA), nanoapatite (NAp) and lauric acid (LA) with two types of Gram-negative periodontal bacteria, Fusobacterium nucleatum and Porphyromonas gingivalis through a disc diffusion and bacterial count tests. The membranes exhibited a pattern of growth inhibition and killing effect against both bacteria. The increase in LA concentration tended to increase the bactericidal activities which indicated by higher diameter of inhibition zone and higher antibacterial percentage. It is shown that the incorporation of LA into the GBR membrane has retarded the growth and proliferation of Gram-negative periodontal bacteria for the treatment of periodontal disease.

Comparison of resorbable poly-L-lactic acid-polyglycolic acid and internal Palmaz stents for the surgical correction of severe tracheomalacia.

Science.gov (United States)

Sewall, Gregory K; Warner, Thomas; Connor, Nadine P; Hartig, Gregory K

2003-06-01

Tracheomalacia (TM) is associated with expiratory airway collapse and potentially fatal respiratory distress. Internal and external tracheal stents and, recently, resorbable biopolymers have been used to treat this condition. In this study, the efficacy and biocompatibility of internal Palmaz stents and external poly-L-lactic acid-polyglycolic acid (PLPG) stents were compared in a model of severe TM induced in piglets. The tracheas were repaired with one of two stenting methods, and the animals survived for up to 16 weeks. Weight gain, adverse respiratory signs and symptoms, tracheal or lung histopathologic changes, and internal and external tracheal diameters were measured. The animals in the PLPG group uniformly were free of respiratory distress and tracheal stenosis or inflammation, whereas all animals in the Palmaz group developed respiratory distress as a result of pneumonia or tracheal stenosis caused by intraluminal granulation tissue. In conclusion, superior efficacy of external, resorbable PLPG stents was found relative to internal Palmaz stents for the surgical repair of severe TM.

Combination of Poly(lactic) Acid and Starch for Biodegradable Food Packaging.

Science.gov (United States)

Muller, Justine; González-Martínez, Chelo; Chiralt, Amparo

2017-08-15

The massive use of synthetic plastics, in particular in the food packaging area, has a great environmental impact, and alternative more ecologic materials are being required. Poly(lactic) acid (PLA) and starch have been extensively studied as potential replacements for non-degradable petrochemical polymers on the basis of their availability, adequate food contact properties and competitive cost. Nevertheless, both polymers exhibit some drawbacks for packaging uses and need to be adapted to the food packaging requirements. Starch, in particular, is very water sensitive and its film properties are heavily dependent on the moisture content, exhibiting relatively low mechanical resistance. PLA films are very brittle and offer low resistance to oxygen permeation. Their combination as blend or multilayer films could provide properties that are more adequate for packaging purposes on the basis of their complementary characteristics. The main characteristics of PLA and starch in terms of not only the barrier and mechanical properties of their films but also of their combinations, by using blending or multilayer strategies, have been analyzed, identifying components or processes that favor the polymer compatibility and the good performance of the combined materials. The properties of some blends/combinations have been discussed in comparison with those of pure polymer films.

Poly(Lactic Acid) Filled with Cassava Starch-g-Soybean Oil Maleate

Science.gov (United States)

Kiangkitiwan, Nopparut; Srikulkit, Kawee

2013-01-01

Poly(lactic acid), PLA, is a biodegradable polymer, but its applications are limited by its high cost and relatively poorer properties when compared to petroleum-based plastics. The addition of starch powder into PLA is one of the most promising efforts because starch is an abundant and cheap biopolymer. However, the challenge is the major problem associated with poor interfacial adhesion between the hydrophilic starch granules and the hydrophobic PLA, leading to poorer mechanical properties. In this paper, soybean oil maleate (SOMA) was synthesized by grafting soybean oil with various weight percents of maleic anhydride (MA) using dicumyl peroxide (DCP) as an initiator. Then, SOMA was employed for the surface modifying of cassava starch powder, resulting in SOMA-g-STARCH. The obtained SOMA-g-STARCH was mixed with PLA in various weight ratios using twin-screw extruder, resulting in PLA/SOMA-g-STARCH. Finally, the obtained PLA/SOMA-g-STARCH composites were prepared by a compression molding machines. The compatibility, thermal properties, morphology properties, and mechanical properties were characterized and evaluated. The results showed that the compatibility, surface appearance, and mechanical properties at 90 : 10 and 80 : 20 ratios of PLA/SOMA-g-STARCH were the best. PMID:24307883

Combination of Poly(lactic) Acid and Starch for Biodegradable Food Packaging

Science.gov (United States)

González-Martínez, Chelo; Chiralt, Amparo

2017-01-01

The massive use of synthetic plastics, in particular in the food packaging area, has a great environmental impact, and alternative more ecologic materials are being required. Poly(lactic) acid (PLA) and starch have been extensively studied as potential replacements for non-degradable petrochemical polymers on the basis of their availability, adequate food contact properties and competitive cost. Nevertheless, both polymers exhibit some drawbacks for packaging uses and need to be adapted to the food packaging requirements. Starch, in particular, is very water sensitive and its film properties are heavily dependent on the moisture content, exhibiting relatively low mechanical resistance. PLA films are very brittle and offer low resistance to oxygen permeation. Their combination as blend or multilayer films could provide properties that are more adequate for packaging purposes on the basis of their complementary characteristics. The main characteristics of PLA and starch in terms of not only the barrier and mechanical properties of their films but also of their combinations, by using blending or multilayer strategies, have been analyzed, identifying components or processes that favor the polymer compatibility and the good performance of the combined materials. The properties of some blends/combinations have been discussed in comparison with those of pure polymer films. PMID:28809808

Ultrafine PEG-coated poly(lactic-co-glycolic acid) nanoparticles formulated by hydrophobic surfactant-assisted one-pot synthesis for biomedical applications.

Science.gov (United States)

Chu, Chih-Hang; Wang, Yu-Chao; Huang, Hsin-Ying; Wu, Li-Chen; Yang, Chung-Shi

2011-05-06

A novel method was developed for the one-pot synthesis of ultrafine poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs), using an emulsion solvent evaporation formulation method. Using either cetyltrimethylammonium bromide (CTAB) or poly(ethylene glycol)-distearyl phosphoethanolamine (PEGPE) as an oily emulsifier during the emulsion process, produced PLGA particle sizes of less than 50 nm, constituting a breakthrough in emulsion formulation methods. The yield of ultrafine PLGA NPs increased with PEGPE/PLGA ratio, reaching a plateau at around 85%, when the PEGPE/PLGA ratio reached 3:1. The PEGPE-PLGA NPs exhibited high drug loading content, reduced burst release, good serum stability, and enhanced cell uptake rate compared with traditional PLGA NPs. Sub-50 nm diameter PEG-coated ultrafine PLGA NPs show great potential for in vivo drug delivery systems.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nucleated Poly(L-lactic acid) with N, N‧-oxalyl bis(benzoic acid) dihydrazide

Science.gov (United States)

Tian, Liang-Liang; Cai, Yan-Hua

2018-04-01

One of the major challenges in the field of Poly(L-lactic acid) (PLLA) is the enhancement of crystallization. In the present work, the evaluation of the influence of N, N‧-oxalyl bis(benzoic acid) dihydrazide (TBOD), as a novel organic nucleating agent, on the non-isothermal crystallization, melting behavior, and thermal stability of PLLA was performed using differential scanning calorimeter and thermogravimetric analysis. Non-isothermal crystallization measurement revealed that TBOD had an excellent accelerating effect for the crystallization of PLLA in cooling, and upon the addition of 3 wt% TBOD, PLLA exhibited the highest onset crystallization temperature and the crystallization peak temperature, as well as the largest non-isothermal crystallization enthalpy. In particular, when the TBOD concentration was 1 wt% ∼ 3 wt%, the onset crystallization temperatures were higher than the theoretical ceiling temperature of crystallization, thoroughly demonstrating the powerful crystallization promoting ability of TBOD. Additionally, the non-isothermal crystallization behavior of PLLA/TBOD depended on the TBOD concentration, cooling rate as well as the final melting temperature. The melting behavior of PLLA/TBOD after non-isothermal crystallization further confirmed the effect of TBOD on the crystallization process and crystal structure of PLLA, and the appearance of the double melting peaks during melting stages was attribute to the melting-recrystallization. For melting behavior after isothermal crystallization, the crystallization temperature and crystallization time significantly affected the melting behavior of PLLA/TBOD. The addition of TBOD could not change the thermal decomposition profile of the PLLA, but the thermal stability did not regularly decrease with increasing of TBOD concentration, indicating that there might exist intermolecular interaction between PLLA and TBOD.

Influence of Poly(L-Lactic Acid Nanofibers and BMP-2–Containing Poly(L-Lactic Acid Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

Directory of Open Access Journals (Sweden)

Markus D. Schofer

2008-01-01

Full Text Available The aim of this study was to characterize synthetic poly-(L-lactic acid (PLLA nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP, osteocalcin (OC, and collagen I (COL-I. Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form.

Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2–Containing Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

Science.gov (United States)

Schofer, Markus D.; Fuchs-Winkelmann, Susanne; Gräbedünkel, Christian; Wack, Christina; Dersch, Roland; Rudisile, Markus; Wendorff, Joachim H.; Greiner, Andreas; Paletta, Jürgen R. J.; Boudriot, Ulrich

2008-01-01

The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form. PMID:19112539

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

Facial volume restoration of the aging face with poly-l-lactic acid.

Science.gov (United States)

Fitzgerald, Rebecca; Vleggaar, Danny

2011-01-01

The purpose of this article is to discuss current techniques used with poly-l-lactic acid to safely and effectively address changes observed in the aging face. Several important points deserve mention. First, this unique agent is not a filler but a stimulator of the host's own collagen, which then acts to volumize tissue in a gradual, progressive, and predictable manner. The technical differences between the use of biostimulatory agents and replacement fillers are simple and straightforward, but are critically important to the safe and successful use of these products and will be reviewed in detail. Second, in addition to gains in technical insights that have improved our understanding of how to use the product to best advantage, where to use the product to best advantage in facial filling has also improved with ever-evolving insights into the changes observed in the aging face. Finally, it is important to recognize that a patient's final outcome, and the amount of product and work it will take to get there, is a reflection of the quality of tissues with which they start. This is, of course, an issue of patient selection and not product selection. © 2011 Wiley Periodicals, Inc.

Negative Outcomes of Poly(l-Lactic Acid) Fiber-Reinforced Scaffolds in an Ovine Total Meniscus Replacement Model.

Science.gov (United States)

Patel, Jay M; Merriam, Aaron R; Kohn, Joachim; Gatt, Charles J; Dunn, Michael G

2016-09-01

Our objective was to test the efficacy of collagen-hyaluronan scaffolds reinforced with poly(l-lactic acid) (PLLA) fibers in an ovine total meniscus replacement model. Scaffolds were implanted into 9 sheep (n = 1 at 8 weeks, n = 2 at 16 weeks, n = 3 at both 24, 32 weeks) following total medial meniscectomy. From 16 weeks on, explants were characterized by confined compression creep, histological, and biochemical analyses. Articular surfaces were observed macroscopically and damage was ranked histologically using the Mankin score. At sacrifice, three of the nine PLLA scaffolds had completely ruptured, and the intact scaffolds experienced progressive shape changes and severe narrowing in the body region at 16, 24, and 32 weeks. Aggregate compressive modulus and permeability did not improve with time. Histological and biochemical analyses showed significantly less extracellular matrix and less matrix organization compared to native tissue. Osteophytes, bone erosion, and cartilage damage were observed, increasing with time postimplantation. A buildup of lactic acid and/or the rapid loss of scaffold mechanical integrity due to PLLA degradation are probable causes for the joint abnormalities observed in this study. These results are in sharp contrast to those of our previous successful total meniscus replacement studies using polyarylate [p(DTD DD)] fiber-reinforced scaffolds. This suggests that PLLA fiber as produced in this study cannot be used as reinforcement for a meniscus replacement scaffold.

Production of D- and L-Lactic Acid by Mono- and Mixed Cultures of Lactobacillus sp.

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Antonija Trontel

2011-01-01

Full Text Available Batch cultivation of monoculture of Lactobacillus sp. and two–strain mixed culture of Lactobacillus sp. and Lactobacillus amylovorus DSM 20531T was carried out with the aim of producing L-(+- and D-(–/L-(+-lactic acid to be implemented in poly(lactic acid polymer production. Metabolic capacity of two Lactobacillus strains to ferment different carbon sources (glucose, sucrose or soluble starch during cultivation in MRS medium at 40 °C, in a laboratory-scale stirred tank bioreactor was defined. Lactobacillus sp. showed similar affinity towards mono- and disaccharide substrates, which were homofermentatively converted mostly to L-(+-lactic acid. L. amylovorus DSM 20531T has been characterized as a D/L-lactate producer and it is capable of conducting simultaneous saccharification and fermentation. Due to the interaction of Lactobacillus sp. with L. amylovorus DSM 20531T, starch was hydrolysed and fermented to the mixture of L-(+- and D-(–-lactic acid. Modified Luedeking-Piret kinetics used for the description of substrate utilization, growth of mono- and mixed cultures and production of lactic acid stereoisomers showed good agreement with experimental data.

Development of Poly(lactic acid)/Chitosan Fibers Loaded with Essential Oil for Antimicrobial Applications

Science.gov (United States)

Liu, Yaowen; Wang, Shuyao; Zhang, Rong; Lan, Wenting; Qin, Wen

2017-01-01

Cinnamon essential oil (CEO) was successfully encapsulated into chitosan (CS) nanoparticles at different loading amounts (1%, 1.5%, 2%, and 2.5% v/v) using oil-in-water (o/w) emulsion and ionic-gelation methods. In order to form active packaging, poly(lactic acid) (PLA) was used to fabricate PLA/CS-CEO composite fibers using a simple electrospinning method. The shape, size, zeta potential, and encapsulation efficacy of the CS-CEO nanoparticles were investigated. The composition, morphology, and release behavior of the composite fibers were investigated. PLA/CS-CEO-1.5 showed good stability and favorable sustained release of CEO, resulting in improved antimicrobial activity compared to the other blends. The PLA/CS-CEO fibers showed high long-term inactivation rates against Escherichia coli and Staphylococcus aureus due to the sustained release of CEO, indicating that the developed PLA/CS-CEO fibers have great potential for active food packaging applications. PMID:28737719

Fabrication of poly (lactic-co-glycolic acid) microcontainers using solvent evaporation with polydimethylsiloxane stencil

Science.gov (United States)

Kim, Chul Min; Byul Lee, Han; Kim, Jong Uk; Kim, Gyu Man

2017-12-01

We present a fabrication method using polydimethylsiloxane (PDMS) stencils and solvent evaporation to prepare microcontainers with a desired shape made from a biodegradable polymer. Poly(lactic-co-glycolic acid) (PLGA) was used for preparing microcontainers, but most polymers are applicable in the proposed method in which solvent evaporation is used to construct microstructures in confined spaces in the stencil. Microcontainers with various shapes were fabricated by controlling the stencil geometry. Furthermore, a porous structure could be prepared in a micromembrane using water porogen. The porous structure was observed using a field emission scanning electron microscope and mass transfer across the porous membrane was examined using a fluorescent dye. The flexibility of the PDMS stencil allowed the fabrication of microcontainers on a curved surface. Finally, it was demonstrated that microcontainers can be used to contain a localized cell culture. The viability and morphology of cultured cells were observed using confocal microscopy over a period of 3 weeks.

Preparation and characterization of poly(lactic acid)/ zinc-aluminium layered double hydroxide nano composites

International Nuclear Information System (INIS)

Eili Mahboobeh; Wan Mohd Zin Wan Yunus; Zobir Hossein; Mansor Ahmad; Norazowa Ibrahim

2009-01-01

Full text: Poly (lactic acid)/ stearate - zinc aluminum layered double hydroxide/ (PLA/ SZnAl LDH) nano composites were prepared via solution intercalation process using a modified ZnAl LDH. The anionic clay Zn 3 Al-NO 3 -LDH was prepared by a co-precipitation method and then modified with stearate ions by ion exchange process. Stearate-ZnAl LDH particles were then homogeneously dispersed in PLA matrix by a solution casting method. The pristine and modified ZnAl LDH was characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy which suggested that the modification was successful. The XRD analysis showed that during modification of LDH, the basal spacing increased from 8.83 Angstrom to 40.1 Angstrom. The PLA/ ZnAl LDH nano composites were characterized by tensile testing and XRD. The obtained nano composites showed dramatic enhancements in elongation at break as compared to those of the pure PLA. XRD results indicated that the materials formed are nano composites. (author)

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

International Nuclear Information System (INIS)

Tsuji, Hiroshi; Sasaki, Hitoshi; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo

2002-01-01

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 10 14 -10 16 ions/cm 2 . 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 3x10 14 ions/cm 2 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 1x10 15 ions/cm 2

Mechanical, Thermal and Morphological Properties of Poly(lactic acid/Epoxidized Palm Olein Blend

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Hazimah Abu Hassan

2012-10-01

Full Text Available Poly(lactic acid (PLA is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt% through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered.

Poly(lactic-co-glycolic) Acid/Solutol HS15-Based Nanoparticles for Docetaxel Delivery.

Science.gov (United States)

Cho, Hyun-Jong; Park, Ju-Hwan; Kim, Dae-Duk; Yoon, In-Soo

2016-02-01

Docetaxel (DCT) is one of anti-mitotic chemotherapeutic agents and has been used for the treatment of gastric cancer as well as head and neck cancer, breast cancer and prostate cancer. Poly(lactic- co-glycolic) acid (PLGA) is one of representative biocompatible and biodegradable polymers, and polyoxyl 15 hydroxystearate (Solutol HS15) is a nonionic solubilizer and emulsifying agent. In this investigation, PLGA/Solutol HS15-based nanoparticles (NPs) for DCT delivery were fabricated by a modified emulsification-solvent evaporation method. PLGA/Solutol HS15/DCT NPs with about 169 nm of mean diameter, narrow size distribution, negative zeta potential, and spherical morphology were prepared. The results of solid-state studies revealed the successful dispersion of DCT in PLGA matrix and its amorphization during the preparation process of NPs. According to the result of in vitro release test, emulsifying property of Solutol HS15 seemed to contribute to the enhanced drug release from NPs at physiological pH. All these findings imply that developed PLGA/Solutol HS15-based NP can be a promising local anticancer drug delivery system for cancer therapy.

Water Absorption and Thermomechanical Characterization of Extruded Starch/Poly(lactic acid/Agave Bagasse Fiber Bioplastic Composites

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F. J. Aranda-García

2015-01-01

Full Text Available Water absorption and thermomechanical behavior of composites based on thermoplastic starch (TPS are presented in this work, wherein the concentration of agave bagasse fibers (ABF, 0–15 wt% and poly(lactic acid (PLA, 0–30 wt% is varied. Glycerol (G is used as starch (S plasticizer to form TPS. Starch stands as the polymer matrix (70/30 wt/wt, S/G. The results show that TPS hygroscopicity decreases as PLA and fiber content increase. Storage, stress-strain, and flexural moduli increase with PLA and/or agave bagasse fibers (ABF content while impact resistance decreases. The TPS glass transition temperature increases with ABF content and decreases with PLA content. Micrographs of the studied biocomposites show a stratified brittle surface with a rigid fiber fracture.

Improved insulin loading in poly (lactic-co-glycolic) acid (PLGA) nanoparticles upon self-assembly with lipids

DEFF Research Database (Denmark)

Garcia Diaz, Maria; Foged, Camilla; Nielsen, Hanne Mørck

2015-01-01

Polymeric nanoparticles are widely investigated as drug delivery systems for oral administration. However, the hydrophobic nature of many polymers hampers effective loading of the particles with hydrophilic macromolecules such as insulin. Thus, the aim of this work was to improve the loading...... of insulin into poly(lactic-co-glycolic) acid (PLGA) nanoparticles by pre-assembly with amphiphilic lipids. Insulin was complexed with soybean phosphatidylcholine or sodium caprate by self-assembly and subsequently loaded into PLGA nanoparticles by using the double emulsion-solvent evaporation technique...... efficiencies (90% as compared to 24% in the absence of lipids). Importantly, the insulin loading capacity was increased up to 20% by using the lipid–insulin complexes. The results further showed that a main fraction of the lipid was incorporated into the nanoparticles and remained associated to the polymer...

Efficacy of Lactic Acid, Lactic Acid-Acetic Acid Blends, and Peracetic Acid To Reduce Salmonella on Chicken Parts under Simulated Commercial Processing Conditions.

Science.gov (United States)

Ramirex-Hernandez, Alejandra; Brashears, Mindy M; Sanchez-Plata, Marcos X

2018-01-01

The poultry processing industry has been undergoing a series of changes as it modifies processing practices to comply with new performance standards for chicken parts and comminuted poultry products. The regulatory approach encourages the use of intervention strategies to prevent and control foodborne pathogens in poultry products and thus improve food safety and protect human health. The present studies were conducted to evaluate the efficacy of antimicrobial interventions for reducing Salmonella on inoculated chicken parts under simulated commercial processing conditions. Chicken pieces were inoculated by immersion in a five-strain Salmonella cocktail at 6 log CFU/mL and then treated with organic acids and oxidizing agents on a commercial rinsing conveyor belt. The efficacy of spraying with six different treatments (sterile water, lactic acid, acetic acid, buffered lactic acid, acetic acid in combination with lactic acid, and peracetic acid) at two concentrations was evaluated on skin-on and skin-off chicken thighs at three application temperatures. Skinless chicken breasts were used to evaluate the antimicrobial efficacy of lactic acid and peracetic acid. The color stability of treated and untreated chicken parts was assessed after the acid interventions. The lactic acid and buffered lactic acid treatments produced the greatest reductions in Salmonella counts. Significant differences between the control and water treatments were identified for 5.11% lactic acid and 5.85% buffered lactic acid in both skin-on and skin-off chicken thighs. No significant effect of treatment temperature for skin-on chicken thighs was found. Lactic acid and peracetic acid were effective agents for eluting Salmonella cells attached to chicken breasts.

[Regulating acid stress resistance of lactic acid bacteria--a review].

Science.gov (United States)

Wu, Chongde; Huang, Jun; Zhou, Rongqing

2014-07-04

As cell factories, lactic acid bacteria are widely used in food, agriculture, pharmaceutical and other industries. Acid stress is one the important survival challenges encountered by lactic acid bacteria both in fermentation process and in the gastrointestinal tract. Recently, the development of systems biology and metabolic engineering brings unprecedented opportunity for further elucidating the acid tolerance mechanisms and improving the acid stress resistance of lactic acid bacteria. This review addresses physiological mechanisms of lactic acid bacteria during acid stress. Moreover, strategies to improve the acid stress resistance of lactic acid were proposed.

21 CFR 184.1061 - Lactic acid.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598... hydrogen cyanide and subsequent hydrolysis to lactic acid. (b) The ingredient meets the specifications of...

[Teichoic acids from lactic acid bacteria].

Science.gov (United States)

Livins'ka, O P; Harmasheva, I L; Kovalenko, N K

2012-01-01

The current view of the structural diversity of teichoic acids and their involvement in the biological activity of lactobacilli has been reviewed. The mechanisms of effects of probiotic lactic acid bacteria, in particular adhesive and immunostimulating functions have been described. The prospects of the use of structure data of teichoic acid in the assessment of intraspecific diversity of lactic acid bacteria have been also reflected.

Development of lovastatin-loaded poly(lactic acid microspheres for sustained oral delivery: in vitro and ex vivo evaluation

Directory of Open Access Journals (Sweden)

Guan QG

2015-02-01

Full Text Available Qigang Guan,1 Wei Chen,2 Xianming Hu2 1Department of Cardiology, The First Affiliated Hospital of China Medical University, Shenyang, People’s Republic of China; 2Department of Pharmaceutical, Shenyang Institute of Pharmaceutical Industry, Shenyang, People’s Republic of China Background: A novel lovastatin (LVT-loaded poly(lactic acid microsphere suitable for oral administration was developed in this study, and in vitro and in vivo characteristics were evaluated. Methods: The designed microspheres were obtained by an improved emulsion-solvent evaporation method. The morphological examination, particle size, encapsulation ratio, drug loading, and in vitro release were characterized. Pharmacokinetics studies were used to show that microspheres possess more advantages than the conventional formulations. Results: By using the emulsion-solvent evaporation method, it was simple to prepare microspheres and easy to scale up production. The morphology of formed microspheres showed a spherical shape with a smooth surface, without any particle aggregation. Mean size of the microspheres was 2.65±0.69 µm; the encapsulation efficiency was 92.5%±3.6%, and drug loading was 16.7%±2.1%. In vitro release indicated that the LVT microspheres had a well-sustained release efficacy, and ex vivo studies showed that after LVT was loaded to microspheres, the area under the plasma concentration-time curve from zero to the last measurable plasma concentration point and the extrapolation to time infinity increased significantly, which represented 2.63-fold and 2.49-fold increases, respectively, compared to suspensions. The rate of ex vivo clearance was significantly reduced. Conclusion: This research proved that poly(lactic acid microspheres can significantly prolong the drug circulation time in vivo and can also significantly increase the relative bioavailability of the drug. Keywords: lovastatin, microspheres, PLA, in vitro release, pharmacokinetics 

Antioxidant activity and controlled drug delivery potential of tragacanth gum-cl- poly (lactic acid-co-itaconic acid) hydrogel.

Science.gov (United States)

Gupta, Vinod Kumar; Sood, Swadeep; Agarwal, Shilpi; Saini, Adesh K; Pathania, Deepak

2018-02-01

Tragacanth gum-cl-poly (lactic acid-co-itaconic acid) (TG-cl-p(LA-co-IA)) hydrogel is synthesized through graft copolymerization reaction using microwave assisted technique. The synthesized hydrogel was characterised using various analytical and characterization techniques such as FTIR, FESEM, XRD, TGA, TEM and SEM. It was observed that, the maximum percentage swelling (P s ) of the hydrogel was 311.61% after 6h at room temperature and 298.06% after 3h at 60°C and TG-cl-p(LA-co-IA) exhibited highest Amoxicillin loading (73%) in double distilled waterafter 24h. From the controlled release studies, it was evident that maximum drug release of about 96% took place at pH 2.2=after 6h. The synthesized hydrogel also showed mild antioxidant properties and 43.85% of free radical scavenging was occurred at a concentration of 640μg/mL and hence it can be effectively used to reduce the oxidative stresses. In addition to this, the antibacterial studies also showed that it is more effective against S. aureus. Copyright © 2017 Elsevier B.V. All rights reserved.

Crystallization kinetics of poly-(lactic acid) with and without talc: Optical microscopy and calorimetric analysis

Science.gov (United States)

Refaa, Z.; Boutaous, M.; Rousset, F.; Fulchiron, R.; Zinet, M.; Xin, S.; Bourgin, P.

2014-05-01

Poly-(lactic acid) or PLA is a biodegradable polymer synthesized from renewable resources. Recently, the discovery of new polymerization routes has allowed increasing the produced volumes. As a consequence, PLA is becoming of great interest for reducing the dependence on petroleum-based plastics. Because of its interesting mechanical properties, PLA is seen as a potential substitute for some usual polymers. However, its relatively slow crystallization kinetics can be a disadvantage with regard to industrial applications. The crystallization kinetics of PLA can be enhanced by adding nucleating agents, which also influences on crystalline morphology and rheological behavior. In the present work, the isothermal quiescent crystallization kinetics of both neat PLA and PLA/talc composite (5 wt% talc) are investigated. The effects of talc on the overall crystallization kinetics and on the crystalline morphology are analyzed using both optical microscopy measurements and thermal analysis by differential scanning calorimetry.

Green Composites Made of Bamboo Fabric and Poly (Lactic) Acid for Packaging Applications—A Review

Science.gov (United States)

Nurul Fazita, M.R.; Jayaraman, Krishnan; Bhattacharyya, Debes; Mohamad Haafiz, M.K.; Saurabh, Chaturbhuj K.; Hussin, M. Hazwan; H.P.S., Abdul Khalil

2016-01-01

Petroleum based thermoplastics are widely used in a range of applications, particularly in packaging. However, their usage has resulted in soaring pollutant emissions. Thus, researchers have been driven to seek environmentally friendly alternative packaging materials which are recyclable as well as biodegradable. Due to the excellent mechanical properties of natural fibres, they have been extensively used to reinforce biopolymers to produce biodegradable composites. A detailed understanding of the properties of such composite materials is vital for assessing their applicability to various products. The present review discusses several functional properties related to packaging applications in order to explore the potential of bamboo fibre fabric-poly (lactic) acid composites for packaging applications. Physical properties, heat deflection temperature, impact resistance, recyclability and biodegradability are important functional properties of packaging materials. In this review, we will also comprehensively discuss the chronological events and applications of natural fibre biopolymer composites. PMID:28773558

Blending of Low-Density Polyethylene and Poly-Lactic Acid with Maleic Anhydride as A Compatibilizer for Better Environmentally Food-Packaging Material

Science.gov (United States)

Setiawan, A. H.; Aulia, F.

2017-05-01

The common conventional food packaging materialsare using a thin layer plastic or film, which is made of a synthetic polymer, such as Low-Density Poly Ethylene (LDPE). However, the use of these polymers hasan adverse impact on the environment, because the synthetic polymersare difficult to degrade naturally. Poly-Lactic Acid (PLA) is a biodegradable polymer that can be substituted to synthetic polymers. Since LDPE and PLA have a difference in polarity, therefore the first step of research is to graft them with maleic anhydride (MAH) for increasing the properties of its miscibility. The interaction between them is confirmed by FTIR; whereas the environment issueis characterized by the water adsorption and biodegradability. The FTIR spectra indicated that there had been an interaction between LDPE and MAH and LDPE/LDPE-g-MAH/PLA blend. Increasing PLA content in the blend affected to the increasing in their water absorption and biodegradable. Poly-blend with 20% PLA content was the optimum composition for environmentally food packaging.

Poly (amido amine) and nano-calcium phosphate bonding agent to remineralize tooth dentin in cyclic artificial saliva/lactic acid

Energy Technology Data Exchange (ETDEWEB)

Liang, Kunneng [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Weir, Michael D.; Reynolds, Mark A. [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Zhou, Xuedong [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Li, Jiyao, E-mail: jiyaoliscu@163.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Xu, Hockin H.K., E-mail: hxu@umaryland.edu [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore County, MD 21250 (United States)

2017-03-01

The objectives of this study were to develop a novel method to remineralize dentin lesions, and investigate the remineralization effects of poly (amido amine) (PAMAM) dendrimer plus a bonding agent with nanoparticles of amorphous calcium phosphate (NACP) in a cyclic artificial saliva/lactic acid environment for the first time. Dentin lesions were produced via phosphoric acid. Four groups were tested: (1) dentin control, (2) dentin with PAMAM, (3) dentin with NACP bonding agent, and (4) dentin with PAMAM plus NACP bonding agent. Specimens were treated with cyclic artificial saliva/lactic acid. The remineralized dentin was examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). NACP bonding agent yielded a dentin shear bond strength similar to commercial controls (Prime & Bond NT, Dentsply; Scotchbond Multi-purpose, 3M) (p > 0.1). Increasing NACP in bonding agent from 0 to 40% did not affect bond strength. NACP bonding agent neutralized the acid and released Ca ions with concentrations of 4 to 20 mmol/L, and P ions of 2 to 9 mmol/L. PAMAM or NACP bonding agent alone achieved slight remineralization. The PAMAM + NACP group achieved the greatest dentin remineralization p < 0.05). At 20 days, PAMAM + NACP increased the hardness of pre-demineralized dentin to reach the normal dentin hardness (p > 0.1). In conclusion, superior remineralization of PAMAM + NACP bonding agent was demonstrated for the first time. PAMAM + NACP bonding agent induced dentin remineralization under acid challenge, when conventional remineralization methods such as PAMAM alone did not work well. The novel PAMAM + NACP bonding agent method is promising to improve the longevity of resin-dentin bonds, inhibit caries, and protect teeth. - Highlights: • PAMAM induced moderate remineralization for dentin in artificial saliva/lactic acid. • Acid challenge reduced the

Poly (amido amine) and nano-calcium phosphate bonding agent to remineralize tooth dentin in cyclic artificial saliva/lactic acid

International Nuclear Information System (INIS)

Liang, Kunneng; Weir, Michael D.; Reynolds, Mark A.; Zhou, Xuedong; Li, Jiyao; Xu, Hockin H.K.

2017-01-01

The objectives of this study were to develop a novel method to remineralize dentin lesions, and investigate the remineralization effects of poly (amido amine) (PAMAM) dendrimer plus a bonding agent with nanoparticles of amorphous calcium phosphate (NACP) in a cyclic artificial saliva/lactic acid environment for the first time. Dentin lesions were produced via phosphoric acid. Four groups were tested: (1) dentin control, (2) dentin with PAMAM, (3) dentin with NACP bonding agent, and (4) dentin with PAMAM plus NACP bonding agent. Specimens were treated with cyclic artificial saliva/lactic acid. The remineralized dentin was examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). NACP bonding agent yielded a dentin shear bond strength similar to commercial controls (Prime & Bond NT, Dentsply; Scotchbond Multi-purpose, 3M) (p > 0.1). Increasing NACP in bonding agent from 0 to 40% did not affect bond strength. NACP bonding agent neutralized the acid and released Ca ions with concentrations of 4 to 20 mmol/L, and P ions of 2 to 9 mmol/L. PAMAM or NACP bonding agent alone achieved slight remineralization. The PAMAM + NACP group achieved the greatest dentin remineralization p < 0.05). At 20 days, PAMAM + NACP increased the hardness of pre-demineralized dentin to reach the normal dentin hardness (p > 0.1). In conclusion, superior remineralization of PAMAM + NACP bonding agent was demonstrated for the first time. PAMAM + NACP bonding agent induced dentin remineralization under acid challenge, when conventional remineralization methods such as PAMAM alone did not work well. The novel PAMAM + NACP bonding agent method is promising to improve the longevity of resin-dentin bonds, inhibit caries, and protect teeth. - Highlights: • PAMAM induced moderate remineralization for dentin in artificial saliva/lactic acid. • Acid challenge reduced the

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

Energy Technology Data Exchange (ETDEWEB)

Matsuda, Yasuhiro [ORNL; Fukatsu, Akinobu [Shizuoka University, Hamamatsu, Japan; Wang, Yangyang [ORNL; Miyamoto, Kazuaki [Shizuoka University, Hamamatsu, Japan; Mays, Jimmy [University of Tennessee, Knoxville (UTK); Tasaka, Shigeru [Shizuoka University, Hamamatsu, Japan

2014-01-01

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

L-lactic acid production by Aspergillus brasiliensis overexpressing the heterologous ldha gene from Rhizopus oryzae.

Science.gov (United States)

Liaud, Nadège; Rosso, Marie-Noëlle; Fabre, Nicolas; Crapart, Sylvaine; Herpoël-Gimbert, Isabelle; Sigoillot, Jean-Claude; Raouche, Sana; Levasseur, Anthony

2015-05-03

Lactic acid is the building block of poly-lactic acid (PLA), a biopolymer that could be set to replace petroleum-based plastics. To make lactic acid production cost-effective, the production process should be carried out at low pH, in low-nutrient media, and with a low-cost carbon source. Yeasts have been engineered to produce high levels of lactic acid at low pH from glucose but not from carbohydrate polymers (e.g. cellulose, hemicellulose, starch). Aspergilli are versatile microbial cell factories able to naturally produce large amounts of organic acids at low pH and to metabolize cheap abundant carbon sources such as plant biomass. However, they have never been used for lactic acid production. To investigate the feasibility of lactic acid production with Aspergillus, the NAD-dependent lactate dehydrogenase (LDH) responsible for lactic acid production by Rhizopus oryzae was produced in Aspergillus brasiliensis BRFM103. Among transformants, the best lactic acid producer, A. brasiliensis BRFM1877, integrated 6 ldhA gene copies, and intracellular LDH activity was 9.2 × 10(-2) U/mg. At a final pH of 1.6, lactic acid titer reached 13.1 g/L (conversion yield: 26%, w/w) at 138 h in glucose-ammonium medium. This extreme pH drop was subsequently prevented by switching nitrogen source from ammonium sulfate to Na-nitrate, leading to a final pH of 3 and a lactic acid titer of 17.7 g/L (conversion yield: 47%, w/w) at 90 h of culture. Final titer was further improved to 32.2 g/L of lactic acid (conversion yield: 44%, w/w) by adding 20 g/L glucose to the culture medium at 96 h. This strain was ultimately able to produce lactic acid from xylose, arabinose, starch and xylan. We obtained the first Aspergillus strains able to produce large amounts of lactic acid by inserting recombinant ldhA genes from R. oryzae into a wild-type A. brasiliensis strain. pH regulation failed to significantly increase lactic acid production, but switching nitrogen source and changing culture feed

Poly-lactic-acid coating of endovascular stents: preliminary results in canine experimental av-fistulae

Energy Technology Data Exchange (ETDEWEB)

Schellhammer, F. [Freiburg Univ. (Germany). Dept. of Neuroradiology; Koeln Univ. (Germany). Dept. of Radiology; Berlis, A. [Bonn Univ. (Germany). Dept. of Radiology; Bloss, H.G. [Freiburg Univ. (Germany). Dept. of Neurosurgery; Pagenstecher, A. [Freiburg Univ. (Germany). Dept. of Neuropathology; Schumacher, M. [Freiburg Univ. (Germany). Dept. of Neuroradiology

2001-02-01

Poly-Lactic-Acid (PLA) was evaluated for coating of vascular endoprotheses in the treatment of experimental arterio-venous-fistulae (AVF). Bilateral carotid-external jugular AVF were created in 5 adult dogs. 7 PLA coated nitinol stents were placed via a transfemoral approach covering 5 AVF. The contralateral AVF remained untreated. Angiography was performed immediately after stent placement, at weeks 1 and 3 and at months 3, 6 and 9. All grafts were removed and underwent histologic examination. In 2 cases the occlusion of the AVF was successful, while misplacement occurred in 3 cases. Occlusion of the parent vessel was disclosed in 3 cases. Histologic examination revealed a mild inflammatory reaction with the presence of macrophages. There was no foreign-body reaction or fragmentation of the arterial vessel wall. PLA, which is a well-known biodegradable material, showed a good mid-term biocompatibility. Elastic mismatch of the non-elastic coating and the self-expandable nitinol stent caused misplacement. Frequent vessel-occlusions were probably due to PLA-filaments fraying into the vessel lumen. Using a different textile structure PLA might be a material suitable for coating endovascular stents. (orig.) [German] In der vorliegenden Arbeit wurden mit Poly-Laktid ummantelte Gefaessprothesen in der Behandlung von experimentell angelegten arterio-venoesen Gefaesskurzschluessen getestet. Gefaesskurzschlussverbindungen der Halsarterien mit der parallel dazu verlaufenden, tiefen Halsvene wurden in 5 Hunden operativ angelegt. 7 mit Poly-Laktid ummantelte Gefaessprothesen aus Nitinol wurden in jeweils eine Halsarterie implantiert, so dass die Gefaesskurzschlussverbindungen vollstaendig ueberdeckt war. Die gegenueberliegende Seite verblieb als Kontrolle unbehandelt. Radiologische Gefaessdarstellungen erfolgten unmittelbar nach Implantation der Gefaessprothese, nach 1 und 3 Wochen sowie nach 3, 6 und 9 Monaten. Alle Prothesen wurden operativ entfernt und feingeweblich

Flexible tension sensor based on poly(l-lactic acid) film with coaxial structure

Science.gov (United States)

Yoshida, Mitsunobu; Onishi, Katsuki; Tanimoto, Kazuhiro; Nishikawa, Shigeo

2017-10-01

We have developed a tension sensor with a coaxial structure using a narrow slit ribbon made of a uniaxially stretched poly(l-lactic acid) (PLLA) film for application to a wearable device. The tension sensor is produced as follows. We used tinsel wire as the center conductor of the sensor. The tinsel wire consists of a yarn of synthetic fibers arranged at the center, with a spirally wound rolled copper foil ribbon on the side surface. Next, slit ribbons obtained from a uniaxially oriented film of PLLA are wound helically on the side surface of the center conductor in the direction of a left-handed screw, at an angle of 45° to the central axis. The rolled copper foil is used as an outer conductor and covers the yarn without a gap. The prototype of the fabricated tension sensor has good flexibility, since the sensor is in the form of a filament and consists of a highly flexible material. For the 1 mm tension sensor, it was found that for a tension of 1 N, a charge of 14 pC was output. It was also found that the sensor maintained its room-temperature sensitivity up to 60 °C. Compared with an existing coaxial line sensor using poly(vinylidene fluoride) (PVDF), the sensor using PLLA does not exhibit pyroelectricity, meaning that no undesirable voltage is generated when in contact with body heat, which is a significant advantage as wearable sensors. The result has demonstrated the potential application of the PLLA film to wearable devices for detecting heartbeat and respiration.

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

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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.

21 CFR 862.1450 - Lactic acid test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Lactic acid test system. 862.1450 Section 862.1450....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base status...

Ketamine nano-delivery based on poly-lactic-co-glycolic acid (PLGA) nanoparticles

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Hirano, Sota; Bovi, Michele; Romeo, Alessandro; Guzzo, Flavia; Chiamulera, Cristiano; Perduca, Massimiliano

2018-04-01

This work describes a novel method for the generation of a ketamine nano-delivery, to improve brain blood barrier permeability and increase drug therapeutic window as anaesthetic, analgesic and potential antidepressant. The approach herein described is based on ketamine-loaded poly-lactic-co-glycolic acid (PLGA) nanoparticles coupled to an apolipoprotein E (ApoE) peptide for delivery to the central nervous system. PLGA particles were synthesized with amount of drug, coupled with the ApoE peptide on the surface, and validated by physical characterization. The produced nanodevice showed a good colloidal stability in water, confirmed by zeta potential measurements, with a diameter in the range of 185-205 nm. The ketamine encapsulation was verified by liquid chromatography-mass spectrometry analyses obtaining an encapsulation efficiency up to 21.2 ± 3.54%. Once the occurrence of ApoE peptide functionalization was confirmed with fluorescence spectroscopy, the thermal stability and morphological information were obtained by differential scanning calorimetry and further dynamic light scattering measurements. The spherical shape and a rough nanoparticles surface were observed by atomic force microscopy. The reliability of this approach may be further developed as a protocol to be used to generate PLGA nanoparticles greater than 100 nm able to better penetrate blood brain barrier and release a neuroactive molecule at lower doses.

An Overview of Poly(lactic-co-glycolic Acid (PLGA-Based Biomaterials for Bone Tissue Engineering

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Piergiorgio Gentile

2014-02-01

Full Text Available Poly(lactic-co-glycolic acid (PLGA has attracted considerable interest as a base material for biomedical applications due to its: (i biocompatibility; (ii tailored biodegradation rate (depending on the molecular weight and copolymer ratio; (iii approval for clinical use in humans by the U.S. Food and Drug Administration (FDA; (iv potential to modify surface properties to provide better interaction with biological materials; and (v suitability for export to countries and cultures where implantation of animal-derived products is unpopular. This paper critically reviews the scientific challenge of manufacturing PLGA-based materials with suitable properties and shapes for specific biomedical applications, with special emphasis on bone tissue engineering. The analysis of the state of the art in the field reveals the presence of current innovative techniques for scaffolds and material manufacturing that are currently opening the way to prepare biomimetic PLGA substrates able to modulate cell interaction for improved substitution, restoration, or enhancement of bone tissue function.

New trends and challenges in lactic acid production on renewable biomass

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Đukić-Vuković Aleksandra J.

2011-01-01

Full Text Available Lactic acid is a relatively cheap chemical with a wide range of applications: as a preservative and acidifying agent in food and dairy industry, a monomer for biodegradable poly-lactide polymers (PLA in pharmaceutical industry, precursor and chemical feedstock for chemical, textile and leather industries. Traditional raw materials for fermentative production of lactic acid, refined sugars, are now being replaced with starch from corn, rice and other crops for industrial production, with a tendency for utilization of agro industrial wastes. Processes based on renewable waste sources have ecological (zero CO2 emission, eco-friendly by-products and economical (cheap raw materials, reduction of storage costs advantages. An intensive research interest has been recently devoted to develop and improve the lactic acid production on more complex industrial by-products, like thin stillage from bioethanol production, corncobs, paper waste, straw etc. Complex and variable chemical composition and purity of these raw materials and high nutritional requirements of Lare the main obstacles in these production processes. Media supplementation to improve the fermentation is an important factor, especially from an economic point of view. Today, a particular challenge is to increase the productivity of lactic acid production on complex renewable biomass. Several strategies are currently being explored for this purpose such as process integration, use of Lwith amylolytic activity, employment of mixed cultures of Land/or utilization of genetically engineered microorganisms. Modern techniques of genetic engineering enable construction of microorganisms with desired characteristics and implementation of single step processes without or with minimal pre-treatment. In addition, new bioreactor constructions (such as membrane bioreactors, utilization of immobilized systems are also being explored. Electrodialysis, bipolar membrane separation process, enhanced filtration

Biocompatibility Assessment of Polyethylene Glycol-Poly L-Lysine-Poly Lactic-Co-Glycolic Acid Nanoparticles In Vitro and In Vivo.

Science.gov (United States)

Guo, Liting; Chen, Baoan; Liu, Ran; Xia, Guohua; Wang, Yonglu; Li, Xueming; Wei, Chen; Wang, Xuemei; Jiang, Hulin

2015-05-01

The present study was designed to evaluate the biocompatibility of nanoparticles polyethylene glycol (PEG)-poly L-lysine (PLL)-poly lactic-co-glycolic acid copolymer (PLGA) (PEG-PLL-PLGA) before clinical application. We applied some tests to assess the safety of PEG-PLL-PLGA nanoparticles (NPs). There was low cytotoxicity of PEG-PLL-PLGA NPs in vitro as detected by MTT assay. Cell apoptosis and intracellular accumulation of PEG-PLL-PLGA were determined by FCM assay. The apoptotic rate induced by nanoparticles and the fluorescence intensity of intracellular daunorubicin (DNR) demonstrated that DNR-PEG-PLL-PLGA could be taken up by the mouse fibroblast cells (L929 cells). Hemolysis test and micronucleus (MN) assay demonstrated that the nanoparticles have no obviously blood toxicity and genotoxicity. DNR-PEG-PLL-PLGA NPs were injected into mice through tail vein to calculate the median lethal dose (LD50), the results showed that they had a wide safe scale. Blood was taken by removing the eyeball of mice to study the influence of DNR-PEG-PLL-PLGA in hepatic and renal functions. The results revealed that there was no significant difference as compared with the control group. Interestingly, the pathologic changes of heart, liver, spleen, lung and kidney were observed in nanoparticles treated mice. Thus, this study demonstrates that PEG-PLL-PLGA NPs appear to be highly biocompatible and safe nanoparticles that can be suitable for further application in the treatment of tumor.

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.

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

International Nuclear Information System (INIS)

Savaris, M.; Santos, V. dos; Brandalise, R.N.

2016-01-01

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 (SH 2 O 2 ), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLA SEtO , PLA SH2O2 , PLA SEB and PLA SGR exhibited thermal and physical changes after being submitted to sterilization processes. PLA SSS showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH 2 O 2 , 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. - Highlights: • PLA was subjected to five different sterilization process. • All sterilization processes do not changed the hydrophilicity of PLA. • Morphological, chemical, physical and thermal changes were observed for the PLA SSS . • The sterilization by saturated steam is not recommended to sterilize PLA.

Biodegradable multilayer barrier films based on alginate/polyethyleneimine and biaxially oriented poly(lactic acid).

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Gu, Chun-Hong; Wang, Jia-Jun; Yu, Yang; Sun, Hui; Shuai, Ning; Wei, Bing

2013-02-15

A layer-by-layer (LBL) approach was used to assemble alternating layers of sodium alginate (ALG)/polyethyleneimine (PEI) on biaxially oriented poly(lactic acid) (BOPLA) films in order to produce bio-based all-polymer thin films with low gas permeability. Increasing the depositing of ALG and PEI from 0 to 30 layers results in large thickness variations (from 0 to 3.92 μm). After 30 ALG/PEI layers are deposited, the resulting assembly has an OTR of 1.22 cm(3)/(m(2) day atm). When multiplied by thickness, the resulting oxygen permeability (OP) is found to be less than 3.8×10(-17) cm(3) cm/cm(2) s Pa, which is almost 3 orders of magnitude lower than that of uncoated BOPLA film (1.8×10(-14) cm(3)cm/cm(2) s Pa). At the same time, the resulting multilayer-coated BOPLA films maintain high optical clarity and tensile properties. This unique barrier thin film has become a promising alternative to non-biodegradable synthetic food packaging materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

21 CFR 582.1061 - Lactic acid.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Lactic acid. 582.1061 Section 582.1061 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1061 Lactic acid. (a) Product. Lactic acid. (b) Conditions of use. This substance is generally...

Effect of Pyruvate Decarboxylase Knockout on Product Distribution Using Pichia pastoris (Komagataella phaffii) Engineered for Lactic Acid Production.

Science.gov (United States)

Melo, Nadiele T M; Mulder, Kelly C L; Nicola, André Moraes; Carvalho, Lucas S; Menino, Gisele S; Mulinari, Eduardo; Parachin, Nádia S

2018-02-16

Lactic acid is the monomer unit of the bioplastic poly-lactic acid (PLA). One candidate organism for lactic acid production is Pichia pastoris , a yeast widely used for heterologous protein production. Nevertheless, this yeast has a poor fermentative capability that can be modulated by controlling oxygen levels. In a previous study, lactate dehydrogenase (LDH) activity was introduced into P. pastoris, enabling this yeast to produce lactic acid. The present study aimed to increase the flow of pyruvate towards the production of lactic acid in P. pastoris . To this end, a strain designated GLp was constructed by inserting the bovine lactic acid dehydrogenase gene (LDHb) concomitantly with the interruption of the gene encoding pyruvate decarboxylase (PDC). Aerobic fermentation, followed by micro-aerophilic culture two-phase fermentations, showed that the GLp strain achieved a lactic acid yield of 0.65 g/g. The distribution of fermentation products demonstrated that the acetate titer was reduced by 20% in the GLp strain with a concomitant increase in arabitol production: arabitol increased from 0.025 g/g to 0.174 g/g when compared to the GS115 strain. Taken together, the results show a significant potential for P. pastoris in producing lactic acid. Moreover, for the first time, physiological data regarding co-product formation have indicated the redox balance limitations of this yeast.

Mapping intermediate degradation products of poly(lactic-co-glycolic acid) in vitro.

Science.gov (United States)

Li, Jian; Nemes, Peter; Guo, Ji

2018-04-01

There is widespread interest in using absorbable polymers, such as poly(lactic-co-glycolic acid) (PLGA), as components in the design and manufacture of new-generation drug eluting stents (DES). PLGA undergoes hydrolysis to progressively degrade through intermediate chemical entities to simple organic acids that are ultimately absorbed by the human body. Understanding the composition and structure of these intermediate degradation products is critical not only to elucidate polymer degradation pathways accurately, but also to assess the safety and performance of absorbable cardiovascular implants. However, analytical approaches to determining the intermediate degradation products have yet to be established and evaluated in a standard or regulatory setting. Hence, we developed a methodology using electrospray ionization mass spectrometry to qualitatively and quantitatively describe intermediate degradation products generated in vitro from two PLGA formulations commonly used in DES. Furthermore, we assessed the temporal evolution of these degradation products using time-lapse experiments. Our data demonstrated that PLGA degradation products via heterogeneous cleavage of ester bonds are modulated by multiple intrinsic and environmental factors, including polymer chemical composition, degradants solubility in water, and polymer synthesis process. We anticipate the methodologies and outcomes presented in this work will elevate the mechanistic understanding of comprehensive degradation profiles of absorbable polymeric devices, and facilitate the design and regulation of cardiovascular implants by supporting the assessments of the associated biological response to degradation products. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1129-1137, 2018. © 2017 Wiley Periodicals, Inc.

Preparation and evaluation of 17-allyamino-17-demethoxygeldanamycin (17-AAG)-loaded poly(lactic acid-co-glycolic acid) nanoparticles.

Science.gov (United States)

Pradhan, Roshan; Poudel, Bijay Kumar; Choi, Ju Yeon; Choi, Im Soon; Shin, Beom Soo; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

2015-01-01

In the present study, we developed the novel 17-allyamino-17-demethoxygeldanamycin (17-AAG)-loaded poly(lactic acid-co-glycolic acid) (PLGA) nanoparticles (NPs) using the combination of sodium lauryl sulfate and poloxamer 407 as the anionic and non-ionic surfactant for stabilization. The PLGA NPs were prepared by emulsification/solvent evaporation method. Both the drug/polymer ratio and phase ratio were 1:10 (w/w). The optimized formulation of 17-AAG-loaded PLGA NPs had a particle size and polydispersity index of 151.6 ± 2.0 and 0.152 ± 0.010 nm, respectively, which was further supported by TEM image. The encapsulation efficiency and drug loading capacity were 69.9 and 7.0%, respectively. In vitro release study showed sustained release. When in vitro release data were fitted to Korsmeyer-Peppas model, the n value was 0.468, which suggested that the drug was released by anomalous or non-Fickian diffusion. In addition, 17-AAG-loaded PLGA NPs in 72 h, displayed approximately 60% cell viability reduction at 10 µg/ml 17-AAG concentration, in MCF-7 cell lines, indicating sustained release from NPs. Therefore, our results demonstrated that incorporation of 17-AAG into PLGA NPs could provide a novel effective nanocarrier for the treatment of cancer.

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

Science.gov (United States)

Kao, Chia-Tze; Lin, Chi-Chang; Chen, Yi-Wen; Yeh, Chia-Hung; Fang, Hsin-Yuan; Shie, Ming-You

2015-11-01

3D printing is a versatile technique to generate large quantities of a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized 3D printed poly(lactic acid) (PLA) scaffolds and use a mussel-inspired surface coating to regulate cell adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared PLA 3D scaffolds coated with polydopamine (PDA). The chemical composition and surface properties of PDA/PLA were characterized by XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation, and cell cycle of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. In addition, the collagen I secreted from cells was increased and promoted cell attachment and cell cycle progression were depended on the PDA content. In osteogenesis assay, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on pure PLA scaffolds. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenic differentiation. Our results demonstrate that the bio-inspired coating synthetic PLA polymer can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to direct the specific responses of hADSCs. Copyright © 2015 Elsevier B.V. All rights reserved.

Efficient production of l-lactic acid by an engineered Thermoanaerobacterium aotearoense with broad substrate specificity

Science.gov (United States)

2013-01-01

Background Efficient conversion of lignocellulosic biomass to optically pure lactic acid is a key challenge for the economical production of biodegradable poly-lactic acid. A recently isolated strain, Thermoanaerobacterium aotearoense SCUT27, is promising as an efficient lactic acid production bacterium from biomass due to its broad substrate specificity. Additionally, its strictly anaerobic and thermophilic characteristics suppress contamination from other microoragnisms. Herein, we report the significant improvements of concentration and yield in lactic acid production from various lignocellulosic derived sugars, achieved by the carbon flux redirection through homologous recombination in T. aotearoense SCUT27. Results T. aotearoense SCUT27 was engineered to block the acetic acid formation pathway to improve the lactic acid production. The genetic manipulation resulted in 1.8 and 2.1 fold increase of the lactic acid yield using 10 g/L of glucose or 10 g/L of xylose as substrate, respectively. The maximum l-lactic acid yield of 0.93 g/g glucose with an optical purity of 99.3% was obtained by the engineered strain, designated as LA1002, from 50 g/L of substrate, which is very close to the theoretical value (1.0 g/g of glucose). In particular, LA1002 produced lactic acid at an unprecedented concentration up to 3.20 g/L using 10 g/L xylan as the single substrate without any pretreatment after 48 h fermentation. The non-sterilized fermentative production of l-lactic acid was also carried out, achieving values of 44.89 g/L and 0.89 g/g mixed sugar for lactic acid concentration and yield, respectively. Conclusions Blocking acetic acid formation pathway in T. aotearoense SCUT27 increased l-lactic acid production and yield dramatically. To our best knowledge, this is the best performance of fermentation on lactic acid production using xylan as the sole carbon source, considering the final concentration, yield and fermentation time. In addition, it should be

Process for the preparation of lactic acid and glyceric acid

Science.gov (United States)

Jackson, James E [Haslett, MI; Miller, Dennis J [Okemos, MI; Marincean, Simona [Dewitt, MI

2008-12-02

Hexose and pentose monosaccharides are degraded to lactic acid and glyceric acid in an aqueous solution in the presence of an excess of a strongly anionic exchange resin, such as AMBERLITE IRN78 and AMBERLITE IRA400. The glyceric acid and lactic acid can be separated from the aqueous solution. Lactic acid and glyceric acid are staple articles of commerce.

RGD-modified poly(D,L-lactic acid nanoparticles enhance tumor targeting of oridonin

Directory of Open Access Journals (Sweden)

Xu J

2012-01-01

Full Text Available Jie Xu, Ji-Hui Zhao, Ying Liu, Nian-Ping Feng, Yong-Tai ZhangSchool of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of ChinaObjective: The purpose of this study was to develop an active targeting strategy to improve the therapeutic antitumor efficacy of oridonin (ORI, the main active ingredient in the medicinal herb Rabdosia rubescens.Methods: A modified spontaneous emulsification solvent diffusion method was used to prepare the ORI-loaded atactic poly(D,L-lactic acid nanoparticles (ORI-PLA-NPs. Surface cross-linking with the peptide Arg-Gly-Asp (RGD further modified the ORI-PLA-NPs, generating ORI-PLA-RGD-NPs. The NPs were characterized and release experiments were performed in vitro. The pharmacokinetics, tissue distribution, and antitumor activity of the NPs were studied in mice bearing hepatocarcinoma 22 (H22-derived tumors.Results: The ORI-PLA-NPs and ORI-PLA-RGD-NPs were smooth, sphere-like, and relatively uniform in size. The RGD surface modification slightly increased the mean particle size (95.8 nm for ORI-PLA-NPs versus 105.2 nm for ORI-PLA-RGD-NPs and considerably altered the surface electrical property (-10.19 mV for ORI-PLA-NPs versus -21.95 mV for ORI-PLA-RGD-NPs, but it had no obvious influence on ORI loading (8.23% ± 0.35% for ORI-PLA-NPs versus 8.02% ± 0.38% for ORI-PLA-RGD-NPs, entrapment efficiency (28.86% ± 0.93% for ORI-PLA-NPs versus 28.24% ± 0.81% for ORI-PLA-RGD-NPs, or the release of ORI. The pharmacokinetic properties of free ORI were improved by encapsulation in NPs, as shown by increased area under the concentration-time curve (11.89 ± 0.35 µg·mL-1 · h for ORI solution versus 22.03 ± 0.01 µg · mL-1 · h for ORI-PLA-RGD-NPs and prolonged mean retention time (2.03 ± 0.09 hours for ORI solution versus 8.68 ± 0.66 hours for ORI-PLA-RGD-NPs. In the tissue distribution study, more ORI targeted tumor tissue in the mice treated with ORI-PLA-RGD-NPs than with ORI

Porosity characterization of biodegradable porous poly (L-lactic acid) electrospun nanofibers

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Valipouri, Afsaneh; Gharehaghaji, Ali Akbar; Alirezazadeh, Azam; Ravandi, Seyed Abdolkarim Hosseini

2017-12-01

Poly-L lactic acid (PLLA) is one of the mostly used fibers in biomedical applications as a biodegradable and biocompatible material. Porosity and fiber diameter distribution are governing factors that determine the performance of nanofibers. Present work aims at investigating the process parameters that are affecting porosity and diameter distribution of PLLA nanofibers. PLLA nanofibers were fabricated through electrospinning method using the solution of PLLA polymer/dichloromethane (DCM). Nanofibers with various fiber diameter distribution and porosity were made by changing of process parameters such as spinning distance (5, 10 and 15 cm), voltage (11 and 15 kV), solution concentration (10, 11 and 12 wt%) and feeding rate (0.3, 0.4 and 0.7 ml h-1). Image processing techniques (with Matlab R2017), surface analysis (with Mountainsmap7) and diameter distribution analysis (with Measurement software) were used to examine surface morphology of samples. The results showed that the fiber diameter distribution becomes wider with increasing the applied voltage and reducing the spinning distance. In the other hand, coarse fibers possessed larger pores while having irregular and fewer pores in comparison to fine fibers. The most uniform nano-web with high porous nanofibers was attained by the choice of the process parameters at the voltage of 11 kV, spinning distance of 15 cm, feeding rate of 0.4 ml h-1 and solution concentration of 10 wt%.

Metabolic Reprogramming of Macrophages Exposed to Silk, Poly(lactic-co-glycolic acid), and Silica Nanoparticles.

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Saborano, Raquel; Wongpinyochit, Thidarat; Totten, John D; Johnston, Blair F; Seib, F Philipp; Duarte, Iola F

2017-07-01

Monitoring macrophage metabolism in response to nanoparticle exposure provides new insights into biological outcomes, such as inflammation or toxicity, and supports the design of tailored nanomedicines. This paper describes the metabolic signature of macrophages exposed to nanoparticles ranging in diameter from 100 to 125 nm and made from silk, poly(lactic-co-glycolic acid) or silica. Nanoparticles of this size and type are currently at various stages of preclinical and clinical development for drug delivery applications. 1 H NMR analysis of cell extracts and culture media is used to quantify the changes in the intracellular and extracellular metabolomes of macrophages in response to nanoparticle exposure. Increased glycolytic activity, an altered tricarboxylic acid cycle, and reduced ATP generation are consistent with a proinflammatory phenotype. Furthermore, amino acids possibly arising from autophagy, the creatine kinase/phosphocreatine system, and a few osmolytes and antioxidants emerge as important players in the metabolic reprogramming of macrophages exposed to nanoparticles. This metabolic signature is a common response to all nanoparticles tested; however, the direction and magnitude of some variations are clearly nanoparticle specific, indicating material-induced biological specificity. Overall, metabolic reprogramming of macrophages can be achieved with nanoparticle treatments, modulated through the choice of the material, and monitored using 1 H NMR metabolomics. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of alkali treatment on the mechanical properties of Poly (lactic acid / Guineacorn husk particulate bio-composites

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Umar SHEHU

2016-12-01

Full Text Available The paper focuses on the influence of alkali treatment on the mechanical properties of biocomposites made from poly(lactic acid (PLA and guineacorn husks particulates (GHP with respect to that of the untreated (untrd biocomposites. The composites were prepared using a single screw extruder and an injection moulding machine with particulate compositions varying from 0-40% at 10% interval. It was observed that the tensile strength of the bio-composites decreased with increase in filler content with a maximum value of 31.24MPa at 10% filler content. The tensile modulus recorded an increase with increase in filler content with a maximum value of 2505MPa at 40% filler content while the maximum hardness stood at 72.9HRR at 30% filler content. The alkali treated bio-composites exhibited better properties as compared to those of the untreated ones.

Fundamental study on improvement of piezoelectricity of poly(ι-lactic acid) and its application to film actuators.

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Tajitsu, Yoshiro

2013-08-01

We designed a new film actuator, whose driving force is generated by a surface wave, which induces rotational motion. Its performance is similar to that of a rotation motor even though the new film actuator has no complex mechanical parts. To realize the film actuator, we used a poly(l-lactic acid) (PLLA) film with improved piezoelectricity. First, we theoretically investigated the necessary conditions for a surface wave to be generated on the end face of a PLLA film by the fusion of its shear piezoelectricity and resonance, and then experimentally realized this. Using the actuator made using the PLLA film, we demonstrated that the clockwise and counterclockwise rotation of an object placed on the end face of the PLLA film actuator could be freely controlled by changing the frequency of the ac voltage applied to the actuator.

Surface characterization and assessment of cell attachment capabilities of thin films fabricated by ion-beam irradiation of poly(L-lactic acid) substrates

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Tanaka, Toshiyuki, E-mail: tttanaka@riken.jp [RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Suzuki, Yoshiaki [RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsuchiya, Koji; Yajima, Hirofumi [Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Thin films can be obtained by ion-beam irradiation of poly(L-lactic acid). Black-Right-Pointing-Pointer Both surfaces of the thin film were carbonized by the irradiation. Black-Right-Pointing-Pointer No significant changes were noticed in the topographies of the two surfaces. Black-Right-Pointing-Pointer Fibroblasts attached firmly to the bottom as well as the top surface of the film. - Abstract: The ion-beam irradiation of substrates of poly(L-lactic acid) (PLLA), a biodegradable polymer, gave rise to exfoliatable thin films when the substrate was immersed in an aqueous solution. The thin films exhibited excellent cell affinity, and hence, can be useful in bioengineering applications. In this study, we characterized both surfaces of the thin films and evaluated their cell attachment capabilities. Each surface was analyzed by X-ray photoelectron spectroscopy (XPS) and dynamic force microscopy (DFM). These analyses showed that carbonization took place at both surfaces. In addition, no significant changes were noticed in the topographies of the two surfaces. Finally, the cell attachment capabilities of the surfaces were determined by culturing mouse fibroblasts on them. The cells attached firmly to the bottom as well as the top surface of the film and were well spread out. These results could be attributed to the carbonization of the surfaces of the thin-film. Such thin films, fabricated by the irradiation of a biodegradable polymer, are expected to find wide application in areas such as tissue regeneration and cell transplantation.

Reducing Water Vapor Permeability of Poly(lactic acid Film and Bottle through Layer-by-Layer Deposition of Green-Processed Cellulose Nanocrystals and Chitosan

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Katalin Halász

2015-01-01

Full Text Available Layer-by-layer electrostatic self-assembly technique was applied to improve the barrier properties of poly(lactic acid (PLA films and bottles. The LbL process was carried out by the alternate adsorption of chitosan (CH (polycation and cellulose nanocrystals (CNC produced via ultrasonic treatment. Four bilayers (on each side of chitosan and cellulose nanocrystals caused 29 and 26% improvement in barrier properties in case of films and bottles, respectively. According to the results the LbL process with CH and CNC offered a transparent “green” barrier coating on PLA substrates.

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

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

2014-01-01

Neural stem cells (NSCs) provide promising therapeutic potential for cell replacement therapy in spinal cord injury (SCI). However, high increases of cell viability and poor control of cell differentiation remain major obstacles. In this study, we have developed a non-woven material made of co-electrospun fibers of poly L-lactic acid and gelatin with a degradation rate and mechanical properties similar to peripheral nerve tissue and investigated their effect on cell survival and differentiation into motor neuronal lineages through the controlled release of retinoic acid (RA) and purmorphamine. Engineered Neural Stem-Like Cells (NSLCs) seeded on these fibers, with and without the instructive cues, differentiated into β-III-tubulin, HB-9, Islet-1, and choactase-positive motor neurons by immunostaining, in response to the release of the biomolecules. In addition, the bioactive material not only enhanced the differentiation into motor neuronal lineages but also promoted neurite outgrowth. This study elucidated that a combination of electrospun fiber scaffolds, neural stem cells, and controlled delivery of instructive cues could lead to the development of a better strategy for peripheral nerve injury repair. Copyright © 2013 Elsevier Ltd. All rights reserved.

Unprecedented access to strong and ductile poly(lactic acid) by introducing In Situ Nanofibrillar Poly(butylene succinate) for green packaging.

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Xie, Lan; Xu, Huan; Niu, Ben; Ji, Xu; Chen, Jun; Li, Zhong-Ming; Hsiao, Benjamin S; Zhong, Gan-Ji

2014-11-10

The notion of toughening poly(lactic acid) (PLA) by adding flexible biopolymers has generated enormous interest but has yielded few desirable advances, mainly blocked by the sacrifice of strength and stiffness due to uncontrollable phase morphology and poor interfacial interactions. Here the phase control methodology, that is, intense extrusion compounding followed by "slit die extrusion-hot stretching-quenching" technique, was proposed to construct well-aligned, stiff poly(butylene succinate) (PBS) nanofibrils in the PLA matrix for the first time. We show that generating nanosized discrete droplets of PBS phase during extrusion compounding is key to enable the development of in situ nanofibrillar PBS assisted by the shearing/stretching field. The size of PBS nanofibrils strongly dependent on the PBS content, showing an increased average diameter from 83 to 116 and 236 nm for the composites containing 10, 20, and 40 wt % nanofibrils, respectively. More importantly, hybrid shish-kebab superstructure anchoring ordered PLA kebabs were induced by the PBS nanofibrils serving as the central shish, conferring the creation of tenacious interfacial crystalline ligaments. The exceptional combination of strength, modulus, and ductility for the composites loaded 40 wt % PBS nanofibrils were demonstrated, outperforming pure PLA with the increments of 31, 51, and 72% in strength, modulus, and elongation at break (56.4 MPa, 1702 MPa, and 92.4%), respectively. The high strength, modulus, and ductility are unprecedented for PLA and are in great potential need for packaging applications.

Gold nanorod–based poly(lactic-co-glycolic acid with manganese dioxide core–shell structured multifunctional nanoplatform for cancer theranostic applications

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Wang L

2017-04-01

Full Text Available Lei Wang,1–3 Dong Li,1,2 Yongwei Hao,1,2 Mengya Niu,1,2 Yujie Hu,1,2 Hongjuan Zhao,1,2 Junbiao Chang,2,3 Zhenzhong Zhang,1,2 Yun Zhang1,2 1School of Pharmaceutical Sciences, Zhengzhou University, 2Key Laboratory of Targeting Therapy and Diagnosis for Critical Disease, Henan Province, 3School of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, People’s Republic of China Abstract: Recently, photothermal therapy has become a promising strategy in tumor treatment. However, the therapeutic effect was seriously hampered by the low tissue penetration of laser. Therefore, in this study, radiofrequency (RF with better tissue penetration was used for tumor hyperthermia. First, one type of gold nanorods (AuNRs suitable for RF hyperthermia was selected. Then, poly(lactic-co-glycolic acid (PLGA nanoparticles (NPs loaded with AuNRs and docetaxel (DTX (PLGA/AuNR/DTX NPs were constructed. Finally, manganese dioxide (MnO2 ultrathin nanofilms were coated on the surfaces of PLGA/AuNR/DTX NPs by the reduction of KMnO4 to construct the PLGA/AuNR/DTX@MnO2 drug delivery system. This drug delivery system can not only be used for the combined therapy of chemotherapy and RF hyperthermia but can also produce Mn2+ to enable magnetic resonance imaging. Furthermore, the RF hyperthermia and the degradation of MnO2 can significantly promote the controlled drug release in a tumor region. The in vitro and in vivo results suggested that the PLGA/AuNR/DTX@MnO2 multifunctional drug delivery system is a promising nanoplatform for effective cancer theranostic applications. Keywords: poly(lactic-co-glycolic acid, gold nanorod, manganese dioxide, radiofrequency, hyperthermia, dual-mode imaging, controlled release

Effects of radiation-induced crosslinking on thermal and mechanical properties of poly(lactic acid) composites reinforced by basalt fiber

International Nuclear Information System (INIS)

Liu Meihua; Zhang Wanxi; Yin Yuan; Wei Wei; Zheng Chunbai; Deng Pengyang; Shen Shirley

2013-01-01

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)

Enhancement of human mesenchymal stem cell infiltration into the electrospun poly(lactic-co-glycolic acid) scaffold by fluid shear stress.

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Kim, Min Sung; Lee, Mi Hee; Kwon, Byeong-Ju; Koo, Min-Ah; Seon, Gyeung Mi; Park, Jong-Chul

The infiltration of the cells into the scaffolds is important phenomenon to give them good biocompatibility and even biodegradability. Fluid shear stress is one of the candidates for the infiltration of cells into scaffolds. Here we investigated the directional migration of human mesenchymal stem cells and infiltration into PLGA scaffold by fluid shear stress. The human mesenchymal stem cells showed directional migrations following the direction of the flow (8, 16 dyne/cm(2)). In the scaffold models, the fluid shear stress (8 dyne/cm(2)) enhanced the infiltration of cells but did not influence on the infiltration of Poly(lactic-co-glycolic acid) particles. Copyright © 2015 Elsevier Inc. All rights reserved.

Synthesis and Properties of Carbon Nanotube-Grafted Silica Nanoarchitecture-Reinforced Poly(Lactic Acid

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Yao-Wen Hsu

2017-07-01

Full Text Available A novel nanoarchitecture-reinforced poly(lactic acid (PLA nanocomposite was prepared using multi-walled carbon nanotube (MWCNT-grafted silica nanohybrids as reinforcements. MWCNT-grafted silica nanohybrids were synthesized by the generation of silica nanoparticles on the MWCNT surface through the sol-gel technique. This synthetic method involves organo-modified MWCNTs that are dispersed in tetrahydrofuran, which incorporates tetraethoxysilane that undergoes an ultrasonic sol-gel process. Gelation yielded highly dispersed silica on the organo-modified MWCNTs. The structure and properties of the nanohybrids were established using 29Si nuclear magnetic resonance, Raman spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The resulting MWCNT nanoarchitectures were covalently assembled into silica nanoparticles, which exhibited specific and controllable morphologies and were used to reinforce biodegradable PLA. The tensile strength and the heat deflection temperature (HDT of the PLA/MWCNT-grafted silica nanocomposites increased when the MWCNT-grafted silica was applied to the PLA matrix; by contrast, the surface resistivity of the PLA/MWCNT-grafted silica nanocomposites appeared to decline as the amount of MWCNT-grafted silica in the PLA matrix increased. Overall, the reinforcement of PLA using MWCNT-grafted silica nanoarchitectures was efficient and improved its mechanical properties, heat resistance, and electrical resistivity.

Poly(L-lactic acid) nanofibers containing Cissus quadrangularis induced osteogenic differentiation in vitro.

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Parvathi, K; Krishnan, Amit G; Anitha, A; Jayakumar, R; Nair, Manitha B

2018-04-15

Cissus quadrangularis (CQ) is known as "bone setter" in Ayurvedic Medicine because of its ability to promote fracture healing. Polymers incorporated with CQ at lower concentration have shown to enhance osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro. However, for the healing of clinically relevant critical sized bone defects, large amount of CQ would be required. Based on this perception, a herbal fibrous sheet containing high weight percentage of CQ [20,40 and 60wt/wt% in poly (L-lactic acid) (PLLA)] was fabricated through electrospinning. The solution concentration, flow rate, voltage and tip-target distance was optimized to obtain nanofibers. The hydrophobicity of PLLA fibers was reduced through CQ incorporation. There was considerable increase in the adhesion, proliferation and osteogenic differentiation of MSCs on herbal fibers than normal fibers, mainly on P-Q20 and P-CQ40. MSCs were differentiated into osteoblasts without providing any osteogenic supplements in the medium, indicating its osteoinductive capability. The herbal sheet also could promote mineralization when immersed in simulated body fluid for 14days. These studies specify that PLLA nanofibers loaded with 20 and 40wt% of CQ could serve as a potential candidate for bone tissue engineering applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Elastic Evaluation of Poly(Lactic Acid) Electrospun Membranes Using the Pulsed Photoacoustic Technique

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Navarrete, M.; Vera-Graziano, R.; Maciel-Cerda, A.; Sánchez-Arévalo, F. M.; Godínez, F. A.

2017-08-01

Fibrous membranes manufactured by electrospinning possess unique features such as a high porosity and large specific surface area, making them suitable for applications in tissue engineering. However, the determination of their mechanical behavior under different loading conditions remains one of the most difficult technical problems for researchers to overcome. While the tensile properties of this kind of membrane are commonly reported in the literature, few explorations of their properties in other directions have been reported. In this paper, the pulsed photoacoustic technique is employed to obtain the elastic constants of electrospun non-woven membranes, specifically in two directions ( L, T). The electrospun samples are hybrid fiber membranes of poly(lactic acid) and hydroxyapatite (HA) nanoparticles at different concentrations. It is found that the concentration of HA nanoparticles determines the mechanical response of the membrane, where the nanoparticles act either as a reinforcement or as a mesh defect. The elastic constants (EL, ET, GL, GT, vL, ν T) are obtained through velocity waves related to the stress-strain equations, using samples with two different geometries and considering the electrospinning mats as a transversely isotropic material. These values are compared to those acquired using macro-tensile testing equipment according to the ASTM D1708 standard.

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

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Savaris, M.; Santos, V. dos, E-mail: vsantos2@ucs.br; 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 (SH{sub 2}O{sub 2}), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLA{sub SEtO}, PLA{sub SH2O2}, PLA{sub SEB} and PLA{sub SGR} exhibited thermal and physical changes after being submitted to sterilization processes. PLA{sub SSS} showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH{sub 2}O{sub 2}, 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. - Highlights: • PLA was subjected to five different sterilization process. • All sterilization processes do not changed the hydrophilicity of PLA. • Morphological, chemical, physical and thermal changes were observed for the PLA{sub SSS}. • The sterilization by saturated steam is not recommended to sterilize PLA.

Poly lactic acid based injectable delivery systems for controlled release of a model protein, lysozyme.

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Al-Tahami, Khaled; Meyer, Amanda; Singh, Jagdish

2006-02-01

The objective of this study was to evaluate the critical formulation parameters (i.e., polymer concentration, polymer molecular weight, and solvent nature) affecting the controlled delivery of a model protein, lysozyme, from injectable polymeric implants. The conformational stability and biological activity of the released lysozyme were also investigated. Three formulations containing 10%, 20%, and 30% (w/v) poly lactic acid (PLA) in triacetin were investigated. It was found that increasing polymer concentration in the formulations led to a lower burst effect and a slower release rate. Formulation with a high molecular weight polymer showed a greater burst effect as compared to those containing low molecular weight. Conformational stability and biological activity of released samples were studied by differential scanning calorimeter and enzyme activity assay, respectively. The released samples had significantly (P solution kept at same conditions). Increasing polymer concentration increased both the conformational stability and the biological activity of released lysozyme. In conclusion, phase sensitive polymer-based delivery systems were able to deliver a model protein, lysozyme, in a conformationally stable and biologically active form at a controlled rate over an extended period.

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

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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.

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

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Toshiyuki Suzuki

2014-12-01

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

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

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

2016-04-01

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

Aluminum Silicate Nanotube Coating of Siloxane-Poly(lactic acid-Vaterite Composite Fibermats for Bone Regeneration

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Shuji Yamazaki

2012-01-01

Full Text Available In our earlier work, a flexible fibermat consisting of a biodegradable composite with soluble silicate species, which has been reported to enhance bone formation, was prepared successfully using poly(L-lactic acid and siloxane-containing calcium carbonate particles by electrospinning. The fibermat showed enhanced bone formation in an in vivo test. In the present work, to improve the hydrophilicity of skeletal fibers in a fibermat, they were coated with nanotubular aluminum silicate crystals, which have a hydrophilic surface that has excellent affinity to body fluids and a high surface area advantageous for pronounced protein adsorption. The nanotubes were coated easily on the fiber surface using an electrophoretic method. In a conventional contact angle test, a drop of water rapidly penetrated into the nanotube-coated fibermat. The culture test using murine osteoblast-like cells (MC3T3-E1 showed that the cell attachment to the nanotube-coated fibermat at an early stage after seeding was enhanced in comparison with that to the noncoated one. This approach may provide a new method of improving the surface of polymer-based biomaterials.

Poly(lactic-co-glycolic) acid nanoparticles uptake by Vitis vinifera and grapevine-pathogenic fungi

International Nuclear Information System (INIS)

Valletta, Alessio; Chronopoulou, Laura; Palocci, Cleofe; Baldan, Barbara; Donati, Livia; Pasqua, Gabriella

2014-01-01

Poly(lactic-co-glycolic) acid (PLGA)-based NPs are currently considered among the most promising drug carriers, nevertheless their use in plants has never been investigated. In this work, for the first time, we demonstrated the ability of PLGA NPs to cross the plant cell wall and membrane of Vitis vinifera cell cultures and grapevine-pathogenic fungi. By means of fluorescence microscopy, we established that PLGA NPs can enter in grapevine leaf tissues through stomata openings and that they can be absorbed by the roots and transported to the shoot through vascular tissues. TEM analysis on cultured cells showed that NPs ≤ 50 nm could enter cells, while bigger ones remained attached to the cell wall. Viability tests demonstrated that PLGA NPs were not cytotoxic for V. vinifera-cultured cells. The cellular uptake of PLGA NPs by some important grapevine-pathogenic fungi has also been observed, thus suggesting that PLGA NPs could be used to deliver antifungal compounds within fungal cells. Overall the results reported suggest that such NPs may play a key role in future developments of agrobiotechnologies, as it is currently happening in biomedicine

Poly(lactic-co-glycolic) acid nanoparticles uptake by Vitis vinifera and grapevine-pathogenic fungi

Energy Technology Data Exchange (ETDEWEB)

Valletta, Alessio [“Sapienza” University of Rome, Department of Environmental Biology (Italy); Chronopoulou, Laura; Palocci, Cleofe, E-mail: cleofe.palocci@uniroma1.it [“Sapienza” University of Rome, Department of Chemistry (Italy); Baldan, Barbara [University of Padua, Department of Biology (Italy); Donati, Livia; Pasqua, Gabriella [“Sapienza” University of Rome, Department of Environmental Biology (Italy)

2014-12-15

Poly(lactic-co-glycolic) acid (PLGA)-based NPs are currently considered among the most promising drug carriers, nevertheless their use in plants has never been investigated. In this work, for the first time, we demonstrated the ability of PLGA NPs to cross the plant cell wall and membrane of Vitis vinifera cell cultures and grapevine-pathogenic fungi. By means of fluorescence microscopy, we established that PLGA NPs can enter in grapevine leaf tissues through stomata openings and that they can be absorbed by the roots and transported to the shoot through vascular tissues. TEM analysis on cultured cells showed that NPs ≤ 50 nm could enter cells, while bigger ones remained attached to the cell wall. Viability tests demonstrated that PLGA NPs were not cytotoxic for V. vinifera-cultured cells. The cellular uptake of PLGA NPs by some important grapevine-pathogenic fungi has also been observed, thus suggesting that PLGA NPs could be used to deliver antifungal compounds within fungal cells. Overall the results reported suggest that such NPs may play a key role in future developments of agrobiotechnologies, as it is currently happening in biomedicine.

Morphology, thermal, mechanical, and barrier properties of graphene oxide/poly(lactic acid) nanocomposite films

International Nuclear Information System (INIS)

Kim, Seong Woo; Choi, Hyun Muk

2016-01-01

To improve the physical and gas barrier properties of biodegradable poly(lactic acid) (PLA) film, two graphene nanosheets of highly functionalized graphene oxide (0.3 wt% to 0.7 wt%) and low-functionalized graphene oxide (0.5 wt%) were incorporated into PLA resin via solution blending method. Subsequently, we investigated the effects of material parameters such as loading level and degree of functionalization for the graphene nanosheets on the morphology and properties of the resultant nanocomposites. The highly functionalized graphene oxide (GO) caused more exfoliation and homogeneous dispersion in PLA matrix as well as more sustainable suspensions in THF, compared to low-functionalized graphene oxide (LFGO). When loaded with GO from 0.3 wt% to 0.7 wt%, the glass transition temperature, degree of crystallinity, tensile strength and modulus increased steadily. The GO gave rise to more pronounced effect in the thermal and mechanical reinforcement, relative to LFGO. In addition, the preparation of fairly transparent PLA-based nanocomposite film with noticeably improved barrier performance achieved only when incorporated with GO up to 0.7wt%. As a result, GO may be more compatible with hydrophilic PLA resin, compared to LFGO, resulting in more prominent enhancement of nanocomposites properties.

Nanofiber mats composed of a chitosan-poly(d,l-lactic-co-glycolic acid)-poly(ethylene oxide) blend as a postoperative anti-adhesion agent.

Science.gov (United States)

Ko, Jae Eok; Ko, Young-Gwang; Kim, Won Il; Kwon, Oh Kyoung; Kwon, Oh Hyeong

2017-10-01

Postoperative tissue adhesion causes serious complications and suffering in 90% of patients after peritoneum surgery, while commercial anti-adhesion agents cannot completely prevent postoperative peritoneal adhesions. This study demonstrates electrospining of a blended solution of chitosan, poly(d,l-lactic-co-glycolic acid) (PLGA), and poly(ethylene oxide) (PEO) to fabricate a chitosan-based nanofibrous mat as a postoperative anti-adhesion agent. Rheological studies combined with scanning electron microscopy reveal that the spinnability of the chitosan-PLGA solution could be controlled by adjusting the blend ratio and concentration with average fiber diameter from 634 to 913 nm. Biodegradation of the nanofiber specimens showed accelerated hydrolysis by chitosan. Proliferation of fibroblasts and antimicrobial activity of nanofibers containing chitosan was analyzed. Abdominal defects with cecum adhesion in rats demonstrated that the blend nanofiber mats were effective in preventing tissue adhesion as a barrier (4 weeks after abdominal surgery) by coverage of exfoliated peritoneum and insufficient wound sites at the beginning of the wound healing process. Chitosan-PLGA-PEO blend nanofiber mats will provide a promising key as a postoperative anti-adhesion agent. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1906-1915, 2017. © 2016 Wiley Periodicals, Inc.

The influence of nanotexturing of poly(lactic-co-glycolic acid) films upon human ovarian cancer cell attachment

Science.gov (United States)

Yaşayan, Gökçen; Xue, Xuan; Collier, Pamela; Clarke, Philip; Alexander, Morgan R.; Marlow, Maria

2016-06-01

In this study, we have produced nanotextured poly(lactic-co-glycolic acid) (PLGA) films by using polystyrene (PS) particles as a template to make a polydimethylsiloxane mould against which PLGA is solvent cast. Biocompatible, biodegradable and nanotextured PLGA films were prepared with PS particles of diameter of 57, 99, 210, and 280 nm that produced domes of the same dimension in the PLGA surface. The effect of the particulate monolayer templating method was investigated to enable preparation of the films with uniformly ordered surface nanodomes. Cell attachment of a human ovarian cancer cell line (OVCAR3) alone and co-cultured with mesenchymal stem cells (MSCs) was evaluated on flat and topographically nano-patterned surfaces. Cell numbers were observed to increase on the nanotextured surfaces compared to non-textured surfaces both with OVCAR3 cultures and OVCAR3-MSC co-cultures at 24 and 48 h time points.

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)

Schusser, S.; Menzel, S.; Bäcker, M.; Leinhos, M.; Poghossian, A.; Wagner, P.; Schöning, M.J.

2013-01-01

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

Spontaneous Differentiation of Human Mesenchymal Stem Cells on Poly-Lactic-Co-Glycolic Acid Nano-Fiber Scaffold.

Directory of Open Access Journals (Sweden)

Koshiro Sonomoto

Full Text Available Mesenchymal stem cells (MSCs have immunosuppressive activity and can differentiate into bone and cartilage; and thus seem ideal for treatment of rheumatoid arthritis (RA. Here, we investigated the osteogenesis and chondrogenesis potentials of MSCs seeded onto nano-fiber scaffolds (NFs in vitro and possible use for the repair of RA-affected joints.MSCs derived from healthy donors and patients with RA or osteoarthritis (OA were seeded on poly-lactic-glycolic acid (PLGA electrospun NFs and cultured in vitro.Healthy donor-derived MSCs seeded onto NFs stained positive with von Kossa at Day 14 post-stimulation for osteoblast differentiation. Similarly, MSCs stained positive with Safranin O at Day 14 post-stimulation for chondrocyte differentiation. Surprisingly, even cultured without any stimulation, MSCs expressed RUNX2 and SOX9 (master regulators of bone and cartilage differentiation at Day 7. Moreover, MSCs stained positive for osteocalcin, a bone marker, and simultaneously also with Safranin O at Day 14. On Day 28, the cell morphology changed from a spindle-like to an osteocyte-like appearance with processes, along with the expression of dentin matrix protein-1 (DMP-1 and matrix extracellular phosphoglycoprotein (MEPE, suggesting possible differentiation of MSCs into osteocytes. Calcification was observed on Day 56. Expression of osteoblast and chondrocyte differentiation markers was also noted in MSCs derived from RA or OA patients seeded on NFs. Lactic acid present in NFs potentially induced MSC differentiation into osteoblasts.Our PLGA scaffold NFs induced MSC differentiation into bone and cartilage. NFs induction process resembled the procedure of endochondral ossification. This finding indicates that the combination of MSCs and NFs is a promising therapeutic technique for the repair of RA or OA joints affected by bone and cartilage destruction.

Poly(lactic acid)-Based in Situ Microfibrillar Composites with Enhanced Crystallization Kinetics, Mechanical Properties, Rheological Behavior, and Foaming Ability.

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Kakroodi, Adel Ramezani; Kazemi, Yasamin; Ding, WeiDan; Ameli, Aboutaleb; Park, Chul B

2015-12-14

Melt blending is one of the most promising techniques for eliminating poly(lactic acid)'s (PLA) numerous drawbacks. However, success in a typical melt blending process is usually achieved through the inclusion of high concentrations of a second polymeric phase which can compromise PLA's green nature. In a pioneering study, we introduce the production of in situ microfibrillar PLA/polyamide-6 (PA6) blends as a cost-effective and efficient technique for improving PLA's properties while minimizing the required PA6 content. Predominantly biobased products, with only 3 wt % of in situ generated PA6 microfibrils (diameter ≈200 nm), were shown to have dramatically improved crystallization kinetics, mechanical properties, melt elasticity and strength, and foaming-ability compared with PLA. Crucially, the microfibrillar blends were produced using an environmentally friendly and cost-effective process. Both of these qualities are essential in guarantying the viability of the proposed technique for overcoming the obstacles associated with the vast commercialization of PLA.

Application of rotatable central composite design in the preparation and optimization of poly(lactic-co-glycolic acid) nanoparticles for controlled delivery of paclitaxel.

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Kollipara, Sivacharan; Bende, Girish; Movva, Snehalatha; Saha, Ranendra

2010-11-01

Polymeric carrier systems of paclitaxel (PCT) offer advantages over only available formulation Taxol® in terms of enhancing therapeutic efficacy and eliminating adverse effects. The objective of the present study was to prepare poly (lactic-co-glycolic acid) nanoparticles containing PCT using emulsion solvent evaporation technique. Critical factors involved in the processing method were identified and optimized by scientific, efficient rotatable central composite design aiming at low mean particle size and high entrapment efficiency. Twenty different experiments were designed and each formulation was evaluated for mean particle size and entrapment efficiency. The optimized formulation was evaluated for in vitro drug release, and absorption characteristics were studied using in situ rat intestinal permeability study. Amount of polymer and duration of ultrasonication were found to have significant effect on mean particle size and entrapment efficiency. First-order interactions of amount of miglyol with amount of polymer were significant in case of mean particle size, whereas second-order interactions of polymer were significant in mean particle size and entrapment efficiency. The developed quadratic model showed high correlation (R(2) > 0.85) between predicted response and studied factors. The optimized formulation had low mean particle size (231.68 nm) and high entrapment efficiency (95.18%) with 4.88% drug content. The optimized formulation showed controlled release of PCT for more than 72 hours. In situ absorption study showed faster and enhanced extent of absorption of PCT from nanoparticles compared to pure drug. The poly (lactic-co-glycolic acid) nanoparticles containing PCT may be of clinical importance in enhancing its oral bioavailability.

Miscibility, crystallization and mechanical properties of biodegradable blends of poly(L-lactic acid) and poly(butylene succinate-b-ethylene succinate) multiblock copolymer

International Nuclear Information System (INIS)

Jiao, Ling; Huang, Cai-Li; Zeng, Jian-Bing; Wang, Yu-Zhong; Wang, Xiu-Li

2012-01-01

Highlights: ► The blend of PLLA and PBES showed limited miscibility. ► The crystallization rate of PLLA was accelerated by blending with PBES. ► The crystal structures of PLLA and PBES did not change. - Abstract: Poly(L-lactic acid) (PLLA) is regarded as one of the most promising biobased and biodegradable polymers. However, its application was restricted due to the brittle nature. In the present study, PLLA was blended with a novel biodegradable flexible multiblock copolymer, poly(butylene succinate-b-ethylene succinate) (PBES) to produce new biodegradable materials. PLLA/PBES blends with different composition were prepared by solution blending and casting method with chloroform as a mutual solvent. Miscibility, crystallization behavior, and mechanical properties of the blends were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and tensile tests. The results indicated that PLLA and PBES showed limited miscibility in the amorphous phase. The crystallization rate of PLLA was accelerated with the increase of PBES in the blends while the crystallization mechanism did not change. The results of tensile tests suggest that the blends showed longer elongation at break than neat PLLA. The elongation at break of PLLA was obtained to be 10%, and those of PLLA/PBES 80/20, 60/40, 40/60 and 20/80 were 29, 110, 442, and 455%, respectively.

Cytotoxicity detection of poly(lactic-co-glycolic acid/tricalcium phosphate

Directory of Open Access Journals (Sweden)

Meng SUN

2011-12-01

Full Text Available Objective To detecte the cytotoxicity of the PLGA/TCP(poly(lactic-co-glycolic acid/Tricalcium phosphate composite that based on the precedent experiments conducted in Tsinghua University.Methods Compared with the PLGA scaffold material,observated the surface and interior structure of the PLGA/TCP scaffold material by SEM(scanning electron microscope,the surface and interior of PLGA/TCP scaffold material appeared to be homogeneous porous under SEM,with fairly even porosity distribution.The pore diameter was approximately 400μm.The interpenetrative micro-pores were scattered over bigger pores’ periphery with approximately circular contour and 3~5 μm in diameter.These pores were interpenetrative,the average factor of porosity was 89.6%.And which selected rat L929 cell strain,and detected the cytotoxicity of the PLGA/TCP composite in vitro by MTT method.Results The surface and interior of PLGA/TCP scaffold material appeared to be homogeneous porous under SEM,with fairly even porosity distribution.The pore diameter was approximately 400μm.The interpenetrative micro-pores were scattered over bigger pores’ periphery with approximately circular contour and 3~5 μm in diameter.These pores were interpenetrative,the average factor of porosity was 89.6%.On rat L929 cell strain,used MTT Method to detect the cytotoxicity of the composite PLGA/ TCP in vitro,the result showed that the cytotoxicity of the PLGA/TCP composite was level I,according to the criterion,it can be considered as non cytotoxic.Conclusion This research has proved that the PLGA/TCP compound scaffold material has a more homogeneous structure,with the vesicular interior and the structure of PLGA/TCP composite is similar to natural bone trabecula,PLGA/TCP is non cytotoxicity,which satisfy the basic requirement of biological material application and provides a good experimental foundation for repairing autologous bone defect in the near future.

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.

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

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

2016-03-01

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

Multi-material poly(lactic acid) scaffold fabricated via fused deposition modeling and direct hydroxyapatite injection as spacers in laminoplasty

Science.gov (United States)

Syuhada, Ghifari; Ramahdita, Ghiska; Rahyussalim, A. J.; Whulanza, Yudan

2018-02-01

Nowadays, additive manufacturing method has been used extensively to realize any product with specific attributes rather than the conventional subtractive manufacturing method. For instance, the additive manufacturing has enable us to construct a product layer-by-layer by successively depositing several materials in one session and one platform. This paper studied the properties of a 3D printed scaffold fabricated through Poly(Lactic-acid) (PLA) deposition modelling in combination with injectable hydroxyapatite (HA)/alginate as cell carrier. The scaffold was designed to serve as a spacer in cervical laminoplasty. Therefore, a series of test were conducted to elaborate the mechanical property, porosity and in-vitro toxicity testing. The results showed that the method is reliable to fabricate the scaffold as desired although the toxicity test needs more confirmation.

Fabrication of honeycomb-structured poly(ethylene glycol)-block-poly(lactic acid) porous films and biomedical applications for cell growth

Energy Technology Data Exchange (ETDEWEB)

Yao, Bingjian [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250199 (China); College of chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014 (China); Zhu, Qingzeng, E-mail: qzzhu@sdu.edu.cn [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250199 (China); Yao, Linli [Key Laboratory of the Ministry of Education for Experimental Teratology, Department of Histology and Embryology, Shandong University School of Medicine, 250012 Jinan (China); Hao, Jingcheng [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250199 (China)

2015-03-30

Graphical abstract: - Highlights: • Honeycomb-structured PEG-PLA porous films were fabricated. • The organization of pores depends on molecular weight ratio of PEG-to-PLA block. • The pores in the film were internally decorated with a layer of PEG. • The honeycomb-structured PEG-PLA film was suitable as a substrate for cell growth. - Abstract: A series of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) copolymers with a hydrophobic PLA block of different molecular weights and a fixed length hydrophilic PEG were synthesized successfully and characterized. These amphiphilic block copolymers were used to fabricate honeycomb-structured porous films using the breath figure (BF) templating technique. The surface topology and composition of the highly ordered pattern film were further characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. The results indicated that the PEG-to-PLA block molecular weight ratio influenced the BF film surface topology. The film with the best ordered pores was obtained with a PEG-to-PLA ratio of 2.0 × 10{sup 3}:3.0 × 10{sup 4}. The self-organization of the hydrophilic PEG chains within the pores was confirmed by XPS and fluorescence labeled PEG. A model is proposed to elucidate the stabilization process of the amphiphilic PEG-PLA aggregated architecture on the water droplet-based templates. In addition, GFP-U87 cell viability has been investigated by MTS test and the cell morphology on the honeycomb-structured PEG-PLA porous film has been evaluated using phase-contrast microscope. This porous film is shown to be suitable as a matrix for cell growth.

Comparative Study of Poly (ε-Caprolactone) and Poly(Lactic-co-Glycolic Acid) -Based Nanofiber Scaffolds for pH-Sensing.

Science.gov (United States)

Di, Wenjun; Czarny, Ryan S; Fletcher, Nathan A; Krebs, Melissa D; Clark, Heather A

2016-10-01

This study aims to develop biodegradable and biocompatible polymer-based nanofibers that continuously monitor pH within microenvironments of cultured cells in real-time. In the future, these fibers will provide a scaffold for tissue growth while simultaneously monitoring the extracellular environment. Sensors to monitor pH were created by directly electrospinning the sensor components within a polymeric matrix. Specifically, the entire fiber structure is composed of the optical equivalent of an electrode, a pH-sensitive fluorophore, an ionic additive, a plasticizer, and a polymer to impart mechanical stability. The resulting poly(ε-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA) based sensors were characterized by morphology, dynamic range, reversibility and stability. Since PCL-based nanofibers delivered the most desirable analytical response, this matrix was used for cellular studies. Electrospun nanofiber scaffolds (NFSs) were created directly out of optode material. The resulting NFS sensors respond to pH changes with a dynamic range centered at 7.8 ± 0.1 and 9.6 ± 0.2, for PCL and PLGA respectively. NFSs exhibited multiple cycles of reversibility with a lifetime of at least 15 days with preservation of response characteristics. By comparing the two NFSs, we found PCL-NFSs are more suitable for pH sensing due to their dynamic range and superior reversibility. The proposed sensing platform successfully exhibits a response to pH and compatibility with cultured cells. NSFs will be a useful tool for creating 3D cellular scaffolds that can monitor the cellular environment with applications in fields such as drug discovery and tissue engineering.

Fabrication of honeycomb-structured poly(ethylene glycol)-block-poly(lactic acid) porous films and biomedical applications for cell growth

International Nuclear Information System (INIS)

Yao, Bingjian; Zhu, Qingzeng; Yao, Linli; Hao, Jingcheng

2015-01-01

Graphical abstract: - Highlights: • Honeycomb-structured PEG-PLA porous films were fabricated. • The organization of pores depends on molecular weight ratio of PEG-to-PLA block. • The pores in the film were internally decorated with a layer of PEG. • The honeycomb-structured PEG-PLA film was suitable as a substrate for cell growth. - Abstract: A series of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) copolymers with a hydrophobic PLA block of different molecular weights and a fixed length hydrophilic PEG were synthesized successfully and characterized. These amphiphilic block copolymers were used to fabricate honeycomb-structured porous films using the breath figure (BF) templating technique. The surface topology and composition of the highly ordered pattern film were further characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. The results indicated that the PEG-to-PLA block molecular weight ratio influenced the BF film surface topology. The film with the best ordered pores was obtained with a PEG-to-PLA ratio of 2.0 × 10 3 :3.0 × 10 4 . The self-organization of the hydrophilic PEG chains within the pores was confirmed by XPS and fluorescence labeled PEG. A model is proposed to elucidate the stabilization process of the amphiphilic PEG-PLA aggregated architecture on the water droplet-based templates. In addition, GFP-U87 cell viability has been investigated by MTS test and the cell morphology on the honeycomb-structured PEG-PLA porous film has been evaluated using phase-contrast microscope. This porous film is shown to be suitable as a matrix for cell growth

pH-, Lactic Acid-, and Non-Lactic Acid-Dependent Activities of Probiotic Lactobacilli against Salmonella enterica Serovar Typhimurium

OpenAIRE

Fayol-Messaoudi, Domitille; Berger, Cédric N.; Coconnier-Polter, Marie-Hélène; Liévin-Le Moal, Vanessa; Servin, Alain L.

2005-01-01

The mechanism(s) underlying the antibacterial activity of probiotic Lactobacillus strains appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins and nonbacteriocin, non-lactic acid molecules. Addition of Dulbecco's modified Eagle's minimum essential medium to the incubating medium delays the killing activity of lactic acid. We found that the probiotic strains Lactobacillus johnsonii La1, Lactobacill...

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)

Peleias Junior, Fernando dos Santos; Zeituni, Carlos Alberto; Rostelato, Maria Elisa Chuery Martins; Souza, Carla Daruich de; Mattos, Fabio Rodrigues de; Moura, Eduardo Santana de; Moura, Joao Augusto; Benega, Marcos Antonio Gimenes; Feher, Anselmo; Costa, Osvaldo Luiz da; Rodrigues, Bruna Teiga; Fechine, Guilhermino Jose

2015-01-01

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)

Delivery of vanillin by poly(lactic-acid) nanoparticles: Development, characterization and in vitro evaluation of antioxidant activity.

Science.gov (United States)

Dalmolin, Luciana Facco; Khalil, Najeh Maissar; Mainardes, Rubiana Mara

2016-05-01

Poly(lactic acid) (PLA) nanoparticles containing vanillin were prepared using an emulsion-solvent evaporation technique and were characterized and assessed for their in vitro antioxidant potential. Physicochemical properties of the nanoparticles were characterized by size, polydispersity index, zeta potential, encapsulation efficiency and stability. Solid state and thermal properties were assessed using X-ray diffraction and differential scanning calorimetry, while in vitro drug release profile was also evaluated. Results showed PLA nanoparticles having a characteristic amorphous structure, sizes in the range of 240 nm with high homogeneity in size distribution, zeta potential of -22 mV and vanillin encapsulation efficiency of 41%. In vitro release study showed a slow and sustained release of vanillin governed by diffusion. Nanoparticles were stable over a period of three months. Antioxidant ability of the vanillin-loaded PLA nanoparticles in scavenging the radical 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was inferior to free vanillin and due to its prolonged release showed a profile that was both time and concentration dependent, while free vanillin showed concentration-dependent activity. The study concluded that PLA nanoparticles are potential carriers for vanillin delivery. Copyright © 2016. Published by Elsevier B.V.

In vitro evaluation of the genotoxicity of a family of novel MeO-PEG-poly(D,L-lactic-co-glycolic acid)-PEG-OMe triblock copolymer and PLGA nanoparticles

Energy Technology Data Exchange (ETDEWEB)

He Lili; Yang Likai; Zhang Zhirong; Gong Tao; Deng Li; Sun Xun [Key Laboratory of Drug Targeting and Novel Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan 610041 (China); Gu Zhongwei, E-mail: xunsun22@gmail.co [National Engineering Research Center for Biomaterials, Engineering Research Center of Biomaterials, Sichuan University, Chengdu 610064 (China)

2009-11-11

Despite the booming development of nanoparticle materials for pharmaceutical applications, studies on their genotoxicity are few. In our previous efforts to develop an intravenous nanoparticle material, a family of novel monomethoxy(polyethylene glycol)-poly(D,L-lactic-co-glycolic acid)-monomethoxy (PELGE) polymers was synthesized. The cytotoxicity and genotoxicity of nine kinds of selected blank PELGE and PLGA (poly(D,L-lactic and glycolic acid)) nanoparticles were evaluated using methyl thiazolyl tetrazolium (MTT), micronucleus (MN) and sister chromatid exchange (SCE) assays with or without the addition of a metabolic activation system (S9 mix), using Chinese hamster ovary (CHO) cells. The cytotoxicity of nanoparticles exhibited a dose-dependent response, with a concentration of 5 mg ml{sup -1} being the turning point. The frequencies of MN observed in samples treated with various nanoparticles were not statistically different from those seen in the negative controls in the presence or absence of the S9 mix. Also, no cell cycle delay was observed. The numbers of SCE per cell observed in samples treated with five kinds of PELGE nanoparticles were significantly greater than those found in the negative controls with or without the S9 mix. The discrepancies found in the two assays suggest that the five kinds of nanoparticles may produce only a weakly clastogenic response.

Enhanced osteogenic differentiation and bone regeneration of poly(lactic-co-glycolic acid) by graphene via activation of PI3K/Akt/GSK-3β/β-catenin signal circuit.

Science.gov (United States)

Wu, Xiaowei; Zheng, Shang; Ye, Yuanzhou; Wu, Yuchen; Lin, Kaili; Su, Jiansheng

2018-05-01

The reconstruction of bone defects by guiding autologous bone tissue regeneration with artificial biomaterials is a potential strategy in the area of bone tissue engineering. The development of new polymers with good biocompatibility, favorable mechanical properties, and osteoinductivity is of vital importance. Graphene and its derivatives have attracted extensive interests due to the exceptional physiochemical and biological properties of graphene. In this study, poly(lactic-co-glycolic acid) (PLGA) films incorporated by graphene nanoplates were fabricated. The results indicated that the incorporation of proper graphene nanoplates into poly(lactic-co-glycolic acid) film could enhance the adhesion and proliferation of rat bone marrow-derived mesenchymal stem cells (rBMSCs). The augmentation of alkaline phosphatase activity, calcium mineral deposition, and the expression level of osteogenic-related genes of rBMSCs on the composite films were observed. Moreover, the incorporation of graphene might activate the PI3K/Akt/GSK-3β/β-catenin signaling pathway, which appeared to be the mechanism behind the osteoinductive properties of graphene. Moreover, the in vivo furcation defect implantation results revealed better guiding bone regeneration properties in the graphene-incorporated group. Thus, we highlight this graphene-incorporated film as a promising platform for the growth and osteogenic differentiation of BMSCs that can achieve application in bone regeneration.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Comparative histological evaluation of new tyrosine-derived polymers and poly (L-lactic acid) as a function of polymer degradation.

Science.gov (United States)

Hooper, K A; Macon, N D; Kohn, J

1998-09-05

Previous studies demonstrated that poly(DTE carbonate) and poly (DTE adipate), two tyrosine-derived polymers, have suitable properties for use in biomedical applications. This study reports the evaluation of the in vivo tissue response to these polymers in comparison to poly(L-lactic acid) (PLLA). Typically, the biocompatibility of a material is determined through histological evaluations as a function of implantation time in a suitable animal model. However, due to changes that can occur in the tissue response at different stages of the degradation process, a fixed set of time points is not ideal for comparative evaluations of materials having different rates of degradation. Therefore the tissue response elicited by poly(DTE carbonate), poly(DTE adipate), and PLLA was evaluated as a function of molecular weight. This allowed the tissue response to be compared at corresponding stages of degradation. Poly(DTE adipate) consistently elicited the mildest tissue response, as judged by the width and lack of cellularity of the fibrous capsule formed around the implant. The tissue response to poly(DTE carbonate) was mild throughout the 570 day study. However, the response to PLLA fluctuated as a function of the degree of degradation, exhibiting an increase in the intensity of inflammation as the implant began to lose mass. At the completion of the study, tissue ingrowth into the degrading and disintegrating poly(DTE adipate) implant was evident while no comparative ingrowth of tissue was seen for PLLA. The similarity of the in vivo and in vitro degradation rates of each polymer confirmed the absence of enzymatic involvement in the degradation process. A comparison of molecular weight retention, water uptake, and mass loss in vivo with two commonly used in vitro systems [phosphate-buffered saline (PBS) and simulated body fluid (SBF)] demonstrated that for the two tyrosine-derived polymers the in vivo results were equally well simulated in vitro with PBS and SBF. However

Enzymatic synthesis of 11C-pyruvic acid and 11C-L-lactic acid

International Nuclear Information System (INIS)

Cohen, M.B.; Spolter, L.; Chang, C.C.; Cook, J.S.; Macdonald, N.S.

1980-01-01

L-Lactic acid is formed as the end product of glycolysis under anaerobic conditions in all cells, but this reaction is of special significance in the myocardium. L-Lactic acid is reversibly formed from and is in equilibrium with myocardial pyruvic acid, which is its sole metabolic pathway. 11 C-Pyruvic acid is synthesized from 11 C carbon dioxide using pyruvate-ferredoxin oxidoreductase and coenzymes. The 11 C-pyruvic acid is then converted to 11 -L-lactic acid by lactic acid dehydrogenase. The availability of 11 C-pyruvic acid and 11 C-L-lactic acid will permit the in vivo investigation of lactate metabolism. (author)

PHAGE RESISTANT LACTIC ACID BACTERIAL MUTANTS

DEFF Research Database (Denmark)

2001-01-01

Method of obtaining mutated lactic acid bacteria having a reduced susceptibility towards attack by bacteriophages, the method comprising mutating a gene involved in the pyrimidine metabolism, including pyrG encoding CTP synthetase. Such lactic acid bacteria are useful in starter cultures...

Evaluation of poly-L-lactic acid and polyglycolic acid resorbable stents for repair of tracheomalacia in a porcine model.

Science.gov (United States)

Nalwa, S S; Hartig, G K; Warner, T; Connor, N P; Thielman, M J

2001-11-01

Poly-L-lactic acid and polyglycolic acid (PLPG) resorbable stents may offer a potential solution to the problem of tracheomalacia. Advantages of this material include its strength, its versatile shaping characteristics, and its resorbability, which would preclude surgical removal and allow for airway growth. The purpose of this pilot study was to examine the usefulness of PLPG stents for temporary external airway stenting of tracheomalacia in a porcine model. A severe tracheomalacia was created in 6 pigs by submucosal resection of segments of tracheal cartilage from 6 consecutive rings. The PLPG stent was then shaped to recreate the tracheal contour and sutured to the underlying airway. Endoscopic photodocumentation during spontaneous ventilation was obtained before and after reconstruction. After creation of the malacic tracheal segment, all animals developed stridor, retractions, and cyanosis during spontaneous ventilation. After repair, all animals were extubated without complication. All animals survived the follow-up period of 9 to 12 weeks without evidence of respiratory distress and with rapid weight gain. Repeat bronchoscopy showed no evidence of airway collapse during spontaneous ventilation. Tracheal measurements revealed growth of the stented segment with a mild narrowing within the repaired region. Histologic examination showed preservation of respiratory epithelium. These preliminary findings suggest that PLPG stents may serve a useful role in the surgical management of tracheomalacia.

Regulating performance of poly(L-lactic acid) by Addition of N, N‧-Bis(Salicyloyl) p-phthalic acid dihydrazide

Science.gov (United States)

Cai, Yan-Hua; Tian, Liang-Liang; Zhao, Li-Sha; Zhang, Mei-Xia

2017-10-01

Within this work, the influence of a crystallization accelerator N, N‧-bis(salicyloyl) p-phthalic acid dihydrazide (PAS) on the non-isothermal crystallization behavior, melting behavior, thermal stability, and light transmittance of poly(L-lactic acid) (PLLA) was investigated by differential scanning calorimetry (DSC), x-ray diffraction (XRD), thermogravimetric analysis (TGA), and light transmittance meter. Comparative analysis of the non-isothermal crystallization behavior of the primary PLLA and PLLA/PAS samples revealed an important role of PAS in promoting the crystallization of PLLA in cooling. Additionally, the concentration of PAS and cooling rate also exhibited significant effect on the non-isothermal crystallization process, and the 3 wt% PAS causes the PLLA to have the highest the onset crystallization temperature and the crystallization peak temperature, and the largest non-isothermal crystallization enthalpy. However, the increase of cooling rate resulted in the decrease of crystal growth ability, weakening the crystallization of PLLA. The investigating on the melting behavior under different conditions further confirmed the crystallization promoting effect of PAS for PLLA, and the crystallization temperature, resulting from the different crystal growth rate, affected remarkably the melting behavior of PLLA/3%PAS sample. The addition of PAS could not change the thermal decomposition behavior of the primary PLLA, but decreased the onset decomposition temperature with an increase of PAS concentration in PLLA matrix. Similarly, the incorporation of PAS is unfavourable to the light transmittance of the primary PLLA.

Impact of Nanoclays on the Biodegradation of Poly(Lactic Acid Nanocomposites

Directory of Open Access Journals (Sweden)

Edgar Castro-Aguirre

2018-02-01

Full Text Available Poly(lactic acid (PLA, a well-known biodegradable and compostable polymer, was used in this study as a model system to determine if the addition of nanoclays affects its biodegradation in simulated composting conditions and whether the nanoclays impact the microbial population in a compost environment. Three different nanoclays were studied due to their different surface characteristics but similar chemistry: organo-modified montmorillonite (OMMT, Halloysite nanotubes (HNT, and Laponite® RD (LRD. Additionally, the organo-modifier of MMT, methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium (QAC, was studied. PLA and PLA bio-nanocomposite (BNC films were produced, characterized, and used for biodegradation evaluation with an in-house built direct measurement respirometer (DMR following the analysis of evolved CO2 approach. A biofilm formation essay and scanning electron microscopy were used to evaluate microbial attachment on the surface of PLA and BNCs. The results obtained from four different biodegradation tests with PLA and its BNCs showed a significantly higher mineralization of the films containing nanoclay in comparison to the pristine PLA during the first three to four weeks of testing, mainly attributed to the reduction in the PLA lag time. The effect of the nanoclays on the initial molecular weight during processing played a crucial role in the evolution of CO2. PLA-LRD5 had the greatest microbial attachment on the surface as confirmed by the biofilm test and the SEM micrographs, while PLA-QAC0.4 had the lowest biofilm formation that may be attributed to the inhibitory effect also found during the biodegradation test when the QAC was tested by itself.

Mussel-Inspired Fabrication of Konjac Glucomannan/Poly (Lactic Acid) Cryogels with Enhanced Thermal and Mechanical Properties.

Science.gov (United States)

Wang, Lin; Yuan, Yi; Mu, Ruo-Jun; Gong, Jingni; Ni, Yongsheng; Hong, Xin; Pang, Jie; Wu, Chunhua

2017-12-16

Three-dimensional nanofibers cryogels (NFCs) with both thermally-tolerant and mechanically-robust properties have potential for wide application in biomedical or food areas; however, creating such NFCs has proven to be extremely challenging. In this study, konjac glucomannan (KGM)/poly (lactic acid) (PLA)-based novel NFCs were prepared by the incorporation of the mussel-inspired protein polydopamine (PDA) via a facile and environmentally-friendly electrospinning and freeze-shaping technique. The obtained KGM/PLA/PDA (KPP) NFCs were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and compressive and tensile test. The results showed that the hierarchical cellular structure and physicochemical properties of KPP NFCs were dependent on the incorporation of PDA content. Moreover, the strong intermolecular hydrogen bond interactions among KGM, PLA and PDA also gave KPP NFCs high thermostability and mechanically-robust properties. Thus, this study developed a simple approach to fabricate multifunctional NFCs with significant potential for biomedical or food application.

Mussel-Inspired Fabrication of Konjac Glucomannan/Poly (Lactic Acid Cryogels with Enhanced Thermal and Mechanical Properties

Directory of Open Access Journals (Sweden)

Lin Wang

2017-12-01

Full Text Available Three-dimensional nanofibers cryogels (NFCs with both thermally-tolerant and mechanically-robust properties have potential for wide application in biomedical or food areas; however, creating such NFCs has proven to be extremely challenging. In this study, konjac glucomannan (KGM/poly (lactic acid (PLA-based novel NFCs were prepared by the incorporation of the mussel-inspired protein polydopamine (PDA via a facile and environmentally-friendly electrospinning and freeze-shaping technique. The obtained KGM/PLA/PDA (KPP NFCs were characterized by field emission scanning electron microscopy (FE-SEM, Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and compressive and tensile test. The results showed that the hierarchical cellular structure and physicochemical properties of KPP NFCs were dependent on the incorporation of PDA content. Moreover, the strong intermolecular hydrogen bond interactions among KGM, PLA and PDA also gave KPP NFCs high thermostability and mechanically-robust properties. Thus, this study developed a simple approach to fabricate multifunctional NFCs with significant potential for biomedical or food application.

Radiation induced crosslinking of poly(L-lactic acid) for making the polymeric materials having high thermal stability and improved mechanical properties

International Nuclear Information System (INIS)

Tran Minh Quynh; Tran Bang Diep; Nguyen Van Binh; Nguyen Quang Long; Pham Duy Duong; Hoang Phuong Thao; Hoang Dang Sang; Pham Ngoc Lan

2013-01-01

Different poly(L-lactic acid) (PLLA) have been synthesized from L-lactic acid as well as L-lactide by direct polycondensation and ring opening polymerization. Depending on reaction time, the resulting products having viscosity average molecular weight ranging from 5 to 25,000 g.mol -1 . Plasticization effects of some popular plasticizer, especially is polyethylene glycols (PEG) for the synthesized PLLA were determined. The results suggested that PEG 1000 is a good plasticizer with relative high plasticization effect. The crosslinking plasticized materials were prepared form the plasticized PLLA by irradiation with various radiation doses. The crosslinking structures were introduced in different formulation of PLLA/PEG/TAIC, the crosslinking density increased with radiation dose and seemed to be saturated at 50 kGy. The stable crosslinking structure inhibited the mobility for crystallization of PLLA chains, thermal stability of plasticized PLLA crosslinked with TAIC at 50 kGy become higher than that of initial PLLA with very small endothermic peak at its melting temperature. The stress-strain curves of the crosslinking plasticized PLLA showed that the toughness of the materials reduced but still higher than that of initial PLLA, whereas its tensile strength was much improved by radiation crosslinking. The results also revealed that the crosslinking plasticized PLLA can be completely degraded by proteinase K as well as microorganisms existing in compost. (author)

Plasma Modification of Poly Lactic Acid Solutions to Generate High Quality Electrospun PLA Nanofibers.

Science.gov (United States)

Rezaei, Fatemeh; Nikiforov, Anton; Morent, Rino; De Geyter, Nathalie

2018-02-02

Physical properties of pre-electrospinning polymer solutions play a key role in electrospinning as they strongly determine the morphology of the obtained electrospun nanofibers. In this work, an atmospheric-pressure argon plasma directly submerged in the liquid-phase was used to modify the physical properties of poly lactic acid (PLA) spinning solutions in an effort to improve their electrospinnability. The electrical characteristics of the plasma were investigated by two methods; V-I waveforms and Q-V Lissajous plots while the optical emission characteristics of the plasma were also determined using optical emission spectroscopy (OES). To perform a complete physical characterization of the plasma-modified polymer solutions, measurements of viscosity, surface tension, and electrical conductivity were performed for various PLA concentrations, plasma exposure times, gas flow rates, and applied voltages. Moreover, a fast intensified charge-couple device (ICCD) camera was used to image the bubble dynamics during the plasma treatments. In addition, morphological changes of PLA nanofibers generated from plasma-treated PLA solutions were observed by scanning electron microscopy (SEM). The performed plasma treatments were found to induce significant changes to the main physical properties of the PLA solutions, leading to an enhancement of electrospinnability and an improvement of PLA nanofiber formation.

Studies on the mechanical properties of woven jute fabric reinforced poly(l-lactic acid composites

Directory of Open Access Journals (Sweden)

G.M. Arifuzzaman Khan

2016-01-01

Full Text Available Development of ecofriendly biocomposites to replace non-biodegradable synthetic fiber composites is the main objective of this study. To highlight the biocomposites as a perfect replacement, the plain woven jute fabric (WJF reinforced poly(l-lactic acid (PLLA composites were prepared by the hot press molding method. The influence of woven structure and direction on the mechanical properties i.e. tensile, flexural and impact properties was investigated. The average tensile strength (TS, tensile modulus (TM, flexural strength (FS, flexural modulus (FM, and impact strength (IS of untreated woven jute composite (in warp direction were improved about 103%, 211%, 95.2%, 42.4% and 85.9%, respectively and strain at maximum tensile stress for composite samples was enhanced by 11.7%. It was also found that the strengths and modulus of composites in warp direction are higher than those in weft direction. WJF composites in warp and weft directions presented superior mechanical properties than non-woven jute fabric (NWJF composites. Chemical treatment of jute fabric through benzoylation showed a positive effect on the properties of composites. Morphological studies by SEM demonstrated that better adhesion between the treated fabric and PLLA was achieved.

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

Energy Technology Data Exchange (ETDEWEB)

Lou, Tao, E-mail: taolou72@aliyun.com [College of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071 (China); Wang, Xuejun [College of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071 (China); Yan, Xu [College of Physics & Collaborative Innovation Center for Low-Dimensional Nanomaterials and Optoelectronic Devices, Qingdao University, Qingdao 266071 (China); Miao, Yu [Department of Mechanical Engineering, Columbia University, New York, NY 10027 (United States); Long, Yun-Ze, E-mail: yunzelong@163.com [College of Physics & Collaborative Innovation Center for Low-Dimensional Nanomaterials and Optoelectronic Devices, Qingdao University, Qingdao 266071 (China); Yin, Hai-Lei [Department of Osteology, No. 401 Hospital of P. L. A., Qingdao 266071 (China); Sun, Bin [College of Physics & Collaborative Innovation Center for Low-Dimensional Nanomaterials and Optoelectronic Devices, Qingdao University, Qingdao 266071 (China); Song, Guojun [College of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071 (China)

2016-07-01

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

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.

Investigation on thermomechanical properties of poly (l-lactic acid) for the stretch blow moulding process of bioresorbable vascular scaffold

Science.gov (United States)

Wei, Huidong; Menary, Gary

2017-10-01

Stretch blow moulding process has been used for the manufacture of bioresorbable vascular scaffold (BVS) made by poly (l-lactic acid) (PLLA) to improve its mechanical performance. In order to better understand the process, thermomechanical properties of PLLA were investigated by experimental method. Extruded PLLA sheets were biaxial stretched under strain rate of 1s-1, 4s-1 and 16s-1 to simulate the deformation process applicable in the blow moulding process. Both the equal-biaxial stretch and constant-width stretch were conducted by an in-house developed equipment. By differential scanning calorimeter (DSC), thermal analysis for materials before and after stretch were compared to evaluate the microstructural change of PLLA materials in the deformation process. A constitutive model based on glass rubber model was presented to simulate the mechanical behaviour of PLLA above glass transition under biaxial deformation.

Surgical suture braided with a diclofenac-loaded strand of poly(lactic-co-glycolic acid) for local, sustained pain mitigation.

Science.gov (United States)

Huh, Beom Kang; Kim, Byung Hwi; Kim, Se-Na; Park, Chun Gwon; Lee, Seung Ho; Kim, Ka Ryeong; Heo, Chan Yeong; Choy, Young Bin

2017-10-01

In this work, we propose a surgical suture that can sustainably release diclofenac (DF) for the local pain relief of surgical wounds. We separately fabricated a DF-loaded strand composed of a biodegradable polymer, poly(lactic-co-glycolic acid) (PLGA), which was then braided with a surgical suture already in clinical use, i.e., VICRYL™. In this way, the drug-delivery suture presented herein could release DF in a sustained manner for 10days while maintaining the mechanical strength needed for wound closure. According to the in vivo results of an induced-pain animal model, the drug-delivery suture mitigated pain throughout the period of persistent pain. The histological analysis of tissue around the sutures showed that the drug-delivery suture exhibited biocompatibility comparable to that of the VICRYL™ suture in clinical use. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of Localized Delivery of Diclofenac Sodium from Poly(D,L-Lactic Acid-co-Glycolic Acid)/Poly(Ethylene Glycol) Scaffolds Using an In Vitro Osteoblast Inflammation Model

Science.gov (United States)

Sidney, Laura E.; Heathman, Thomas R.J.; Britchford, Emily R.; Abed, Arif; Rahman, Cheryl V.

2015-01-01

Nonunion fractures and large bone defects are significant targets for osteochondral tissue engineering strategies. A major hurdle in the use of these therapies is the foreign body response of the host. Herein, we report the development of a bone tissue engineering scaffold with the ability to release anti-inflammatory drugs, in the hope of evading this response. Porous, sintered scaffolds composed of poly(D,L-lactic acid-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) were prepared with and without the anti-inflammatory drug diclofenac sodium. Analysis of drug release over time demonstrated a profile suitable for the treatment of acute inflammation with ∼80% of drug released over the first 4 days and a subsequent release of around 0.2% per day. Effect of drug release was monitored using an in vitro osteoblast inflammation model, comprised of mouse primary calvarial osteoblasts stimulated with proinflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ). Levels of inflammation were monitored by cell viability and cellular production of nitric oxide (NO) and prostaglandin E2 (PGE2). The osteoblast inflammation model revealed that proinflammatory cytokine addition to the medium reduced cell viability to 33%, but the release of diclofenac sodium from scaffolds inhibited this effect with a final cell viability of ∼70%. However, releasing diclofenac sodium at high concentrations had a toxic effect on the cells. Proinflammatory cytokine addition led to increased NO and PGE2 production; diclofenac-sodium-releasing scaffolds inhibited NO release by ∼64% and PGE2 production by ∼52%, when the scaffold was loaded with the optimal concentration of drug. These observations demonstrate the potential use of PLGA/PEG scaffolds for localized delivery of anti-inflammatory drugs in bone tissue engineering applications. PMID:25104438

Sensitive determination of D-lactic acid and L-lactic acid in urine by high-performance liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Henry, H; Marmy Conus, N; Steenhout, P; Béguin, A; Boulat, O

2012-04-01

D-lactic acid in urine originates mainly from bacterial production in the intestinal tract. Increased D-lactate excretion as observed in patients affected by short bowel syndrome or necrotizing enterocolitis reflects D-lactic overproduction. Therefore, there is a need for a reliable and sensitive method able to detect D-lactic acid even at subclinical elevation levels. A new and highly sensitive method for the simultaneous determination of L- and D-lactic acid by a two-step procedure has been developed. This method is based on the concentration of lactic acid enantiomers from urine by supported liquid extraction followed by high-performance liquid chromatography-tandem mass spectrometry. The separation was achieved by the use of an Astec Chirobiotic™ R chiral column under isocratic conditions. The calibration curves were linear over the ranges of 2-400 and 0.5-100 µmol/L respectively for L- and D-lactic acid. The limit of detection of D-lactic acid was 0.125 µmol/L and its limit of quantification was 0.5 µmol/L. The overall accuracy and precision were well within 10% of the nominal values. The developed method is suitable for production of reference values in children and could be applied for accurate routine analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Significant thermal energy reduction in lactic acid production process

International Nuclear Information System (INIS)

Mujtaba, Iqbal M.; Edreder, Elmahboub A.; Emtir, Mansour

2012-01-01

Lactic acid is widely used as a raw material for the production of biodegradable polymers and in food, chemical and pharmaceutical industries. The global market for lactic acid is expected to reach 259 thousand metric tons by the year 2012. For batch production of lactic acid, the traditional process includes the following steps: (i) esterification of impure lactic acid with methanol in a batch reactor to obtain methyl lactate (ester), (ii) separation of the ester in a batch distillation, (iii) hydrolysis of the ester with water in a batch reactor to produce lactic acid and (iv) separation of lactic acid (in high purity) in a batch distillation. Batch reactive distillation combines the benefit of both batch reactor and batch distillation and enhances conversion and productivity (Taylor and Krishna, 2000 ; Mujtaba and Macchietto, 1997 ). Therefore, the first and the last two steps of the lactic acid production process can be combined together in batch reactive distillation () processes. However, distillation (batch or continuous) is an energy intensive process and consumes large amount of thermal energy (via steam). This paper highlights how significant (over 50%) reduction in thermal energy consumption can be achieved for lactic acid production process by carefully controlling the reflux ratio but without compromising the product specification. In this paper, only the simultaneous hydrolysis of methyl lactate ester and the separation of lactic acid using batch reactive distillation is considered.

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.

Experimental and computational studies of poly-L-lactic acid for cardiovascular applications: recent progress

Science.gov (United States)

Naseem, Raasti; Zhao, Liguo; Liu, Yang; Silberschmidt, Vadim V.

2017-12-01

Stents are commonly used in medical procedures to alleviate the symptoms of coronary heart disease, a prevalent modern society disease. These structures are employed to maintain vessel patency and restore blood flow. Traditionally stents are made of metals such as stainless steel or cobalt chromium; however, these scaffolds have known disadvantages. An emergence of transient scaffolds is gaining popularity, with the structure engaged for a required period whilst healing of the diseased arterial wall occurs. Polymers dominate a medical device sector, with incorporation in sutures, scaffolds and screws. Thanks to their good mechanical and biological properties and their ability to degrade naturally. Polylactic acid is an extremely versatile polymer, with its properties easily tailored to applications. Its dominance in the stenting field increases continually, with the first polymer scaffold gaining FDA approval in 2016. Still some challenges with PLLA bioresorbable materials remain, especially with regard to understanding their mechanical response, assessment of its changes with degradation and comparison of their performance with that of metallic drug-eluting stent. Currently, there is still a lack of works on evaluating both the pre-degradation properties and degradation performance of these scaffolds. Additionally, there are no established material models incorporating non-linear viscoelastic behaviour of PLLA and its evolution with in-service degradation. Assessing these features through experimental analysis accompanied by analytical and numerical studies will provide powerful tools for design and optimisation of these structures endorsing their broader use in stenting. This overview assesses the recent studies investigating mechanical and computational performance of poly(l-lactic) acid and its use in stenting applications.

Selection of lactic acid bacteria able to ferment inulin hydrolysates

Directory of Open Access Journals (Sweden)

Octavian BASTON

2012-12-01

Full Text Available Eight homofermentative lactic acid bacteria isolates were tested for lactic acid production using chicory and Jerusalem artichoke hydrolysate as substrate. The pH, lactic acid yield and productivity were used to select the best homolactic bacteria for lactic acid production. The selected strains produced lactic acid at maximum yield after 24 hours of fermentation and the productivity was greater at 24 hours of fermentation. From all studied strains, Lb1 and Lb2 showed the best results regarding lactic acid yields andproductivity. After 48 hours of chicory and Jerusalem artichhoke hydrolysates fermentation, from all the studied strains, Lb2 produced the highest lactic acid yield (0.97%. Lb2 produced after 48 hours of fermentation the lowest pH value of 3.45±0.01. Lb2 showed greater lactic acid productivity compared to the other studied lactic acid bacteria, the highest values, 0.13 g·L-1·h-1fromJerusalem artichoke hydrolysate and 0.11g·L-1·h-1 from chicory hydrolysate, being produced after 24 hours of fermentation.

pH-, Lactic acid-, and non-lactic acid-dependent activities of probiotic Lactobacilli against Salmonella enterica Serovar Typhimurium.

Science.gov (United States)

Fayol-Messaoudi, Domitille; Berger, Cédric N; Coconnier-Polter, Marie-Hélène; Liévin-Le Moal, Vanessa; Servin, Alain L

2005-10-01

The mechanism(s) underlying the antibacterial activity of probiotic Lactobacillus strains appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins and nonbacteriocin, non-lactic acid molecules. Addition of Dulbecco's modified Eagle's minimum essential medium to the incubating medium delays the killing activity of lactic acid. We found that the probiotic strains Lactobacillus johnsonii La1, Lactobacillus rhamnosus GG, Lactobacillus casei Shirota YIT9029, L. casei DN-114 001, and L. rhamnosus GR1 induced a dramatic decrease in the viability of Salmonella enterica serovar Typhimurium SL1344 mainly attributable to non-lactic acid molecule(s) present in the cell-free culture supernatant (CFCS). These molecules were more active against serovar Typhimurium SL1344 in the exponential growth phase than in the stationary growth phase. We also showed that the production of the non-lactic acid substance(s) responsible for the killing activity was dependent on growth temperature and that both unstable and stable substances with killing activity were present in the CFCSs. We found that the complete inhibition of serovar Typhimurium SL1344 growth results from a pH-lowering effect.

Novel Method of Lactic Acid Production by Electrodialysis Fermentation

OpenAIRE

Hongo, Motoyoshi; Nomura, Yoshiyuki; Iwahara, Masayoshi

1986-01-01

In lactic acid fermentation by Lactobacillus delbrueckii, the produced lactic acid affected the lactic acid productivity. Therefore, for the purpose of alleviating this inhibitory effect, an electrodialysis fermentation method which can continuously remove produced lactic acid from the fermentation broth was applied to this fermentation process. As a result, the continuation of fermentation activity was obtained, and the productivity was three times higher than in non-pH-controlled fermentati...

Optimization of a biomimetic poly-(lactic acid) ligament scaffold

Science.gov (United States)

Uehlin, Andrew F.

The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was used to create nanofibers of PLA, followed by an induced degradation of the nanofibers via 0.25M NaOH hydrolysis. The effects of the unidirectional electrospinning as well as the effects of NaOH hydrolysis on fiber alignment, fiber diameter, surface morphology, crystallinity, in vitro swelling, immobilization of fibrin, and mechanical properties were investigated, resulting in a modified morphology correlating to the microstructure of native ligament tissue with similar mechanical properties. Furthering the development of the PLA nanomatrix composite, a bioinkjet printer was used to immobilize nanoparticulate hydroxyapatite (HANP) on the surface of the scaffold. A series of 300pL droplets of HANP bioink were printed over a gradient pattern mimetic of (and spatially corresponding to) the mineralization gradient found over the microanatomy at the ACL enthesis. Proliferation and differentiation response of human mesenchymal stem cells (hMSCs) in vitro was assessed on a variety of conditions and combinations of the PLA nanofiber scaffold surface modifications (inclusive and exclusive of HANP, fibrin, and various time dependent NaOH treatments). It was found that a combinatory effect of the HANP gradient with fibrin on 20 minute NaOH treated PLA

Synthesis and Characterization of Quantum Dot-Loaded Poly(lactic-co-glycolic) Acid Nanocomposite Fibers by an Electrospinning Process.

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Ankireddy, Seshadri Reddy; Kim, Jongsung

2017-04-01

Poly(lactic-co-glycolic) acid (PLGA) is one of the most successfully developed biodegradable polymers. PLGA is a copolymer of polylactic and glycolic acid. In this work, quantum dot (QD)-loaded PLGA nanofibers were fabricated via a simple one-step electrospinning process. The surface morphology of the fibers was characterized by scanning electron microscopy (SEM). It was shown that the PLGA nanofibers had both smooth and rough surfaces with an average fiber diameter of 150 ± 25 nm and 350 ± 60 nm for the PLGA and QD-loaded PLGA nanofibers, respectively. The needle size, applied voltage, and solvent flow rate in the syringe were maintained at 23 G, 20 kV, and 1.5 mL/h, respectively. The SEM analysis showed that nanofibers with a very thin and uniform size were formed and the InP/ZnS QDs were homogeneously loaded into the PLGA nanofiber matrix. The thermal properties of the PLGA-QD nanofibers were explored by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The surface chemical structure and functionalities were characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffraction (XRPD).

Porous stable poly(lactic acid)/ethyl cellulose/hydroxyapatite composite scaffolds prepared by a combined method for bone regeneration.

Science.gov (United States)

Mao, Daoyong; Li, Qing; Bai, Ningning; Dong, Hongzhou; Li, Daikun

2018-01-15

A major challenge in bone tissue engineering is the development of biomimetic scaffolds which should simultaneously meet mechanical strength and pore structure requirements. Herein, we combined technologies of high concentration solvent casting, particulate leaching, and room temperature compression molding to prepare a novel poly(lactic acid)/ethyl cellulose/hydroxyapatite (PLA/EC/HA) scaffold. The functional, structural and mechanical properties of the obtained porous scaffolds were characterized. The results indicated that the PLA/EC/HA scaffolds at the 20wt% HA loading level showed optimal mechanical properties and desired porous structure. Its porosity, contact angle, compressive yield strength and weight loss after 56days were 84.28±7.04%, 45.13±2.40°, 1.57±0.09MPa and 4.77±0.32%, respectively, which could satisfy the physiological demands to guide bone regeneration. Thus, the developed scaffolds have potential to be used as a bone substitute material for bone tissue engineering application. Copyright © 2017. Published by Elsevier Ltd.

Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

Science.gov (United States)

Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

2015-12-01

A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

Effect of modified starch and nanoclay particles on biodegradability and mechanical properties of cross-linked poly lactic acid.

Science.gov (United States)

Shayan, M; Azizi, H; Ghasemi, I; Karrabi, M

2015-06-25

Mechanical properties and biodegradation of cross-linked poly(lactic acid) (PLA)/maleated thermoplastic starch (MTPS)/montmorillonite (MMT) nanocomposite were studied. Crosslinking was carried out by adding di-cumyl peroxide (DCP) in the presence of triallyl isocyanurate (TAIC) as coagent. At first, MTPS was prepared by grafting maleic anhydride (MA) to thermoplastic starch in internal mixer. Experimental design was performed by using Box-Behnken method at three variables: MTPS, nanoclay and TAIC at three levels. Results showed that increasing TAIC amount substantially increased the gel fraction, enhanced tensile strength, and caused a decrease in elongation at break. Biodegradation was prevented by increasing TAIC amount in nanocomposite. Increasing MTPS amount caused a slight increase in gel fraction and decreased the tensile strength of nanocomposite. Also, MTPS could increase the elongation at break of nanocomposite and improve the biodegradation. Nanoclay had no effect on the gel fraction, but it improved tensile strength. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation and Characterization of Jute Cellulose Crystals-Reinforced Poly(L-lactic acid Biocomposite for Biomedical Applications

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Mohammed Mizanur Rahman

2014-01-01

Full Text Available Crystalline cellulose was extracted from jute by hydrolysis with 40% H2SO4 to get mixture of micro/nanocrystals. Scanning electron microscope (SEM showed the microcrystalline structure of cellulose and XRD indicated the Iβ polymorph of cellulose. Biodegradable composites were prepared using crystalline cellulose (CC of jute as the reinforcement (3–15% and poly(lactic acid (PLA as a matrix by extrusion and hot press method. CC was cellulose derived from mercerized and bleached jute fiber by acid hydrolysis to remove the amorphous regions. FT-IR studies showed hydrogen bonding between the CC and the PLA matrix. The X-ray diffraction (XRD and differential scanning calorimetry (DSC studies showed that the percentage crystallinity of PLA in composites was found to be higher than that of neat PLA as a result of the nucleating ability of the crystalline cellulose. Furthermore, Vicker hardness and yield strength were found to increase with increasing cellulose content in the composite. The SEM images of the fracture surfaces of the composites were indicative of poor adhesion between the CC and the PLA matrix. The composite with 15% CC showed antibacterial effect though pure films but had no antimicrobial effect; on the other hand its cytotoxicity in biological medium was found to be medium which might be suitable for its potential biomedical applications.

The possibility of lactic acid fermentation in the triticale stillage

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MILICA MARKOVIĆ

2011-06-01

Full Text Available Triticale stillage is a by-product of bioethanol production. A research study was conducted in order to see if triticale stillage is adequate for lactic acid bacteria growth and lactic acid fermentation. Three Lactobacillus strains: Lactobacillus fermentum NRRL-B-75624, Lactobacillus fermentum PL-1, and Lactobacillus plantarum PL-4 were taken into consideration. Lactic acid fermentation was monitored by measuring pH value and titratable acidity. Lactobacillus fermentum PL-1 had the greatest decrease of pH values and increase of titratable acidity so it was chosen for future work. During the research, it was investigated how nutrient composition of triticale stillage and CaCO3 can influence lactic acid fermentation and CaCO3 role in cell protection. The nutrient composition of triticale stillage was satisfactory for lactic acid fermentation. The addition of CaCO3 helped in lactic acid fermentation. Although the titratable acidity in the samples with CaCO3 was lower than in the samples without CaCO3, the number of viable cells was higher for the samples with CaCO3, which showed that CaCO3 protected lactic acid cells from inhibition by lactic acid.

Functionalization of chitosan/poly(lactic acid-glycolic acid) sintered microsphere scaffolds via surface heparinization for bone tissue engineering.

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Jiang, Tao; Khan, Yusuf; Nair, Lakshmi S; Abdel-Fattah, Wafa I; Laurencin, Cato T

2010-06-01

Scaffolds exhibiting biological recognition and specificity play an important role in tissue engineering and regenerative medicine. The bioactivity of scaffolds in turn influences, directs, or manipulates cellular responses. In this study, chitosan/poly(lactic acid-co-glycolic acid) (chitosan/PLAGA) sintered microsphere scaffolds were functionalized via heparin immobilization. Heparin was successfully immobilized on chitosan/PLAGA scaffolds with controllable loading efficiency. Mechanical testing showed that heparinization of chitosan/PLAGA scaffolds did not significantly alter the mechanical properties and porous structures. In addition, the heparinized chitosan/PLAGA scaffolds possessed a compressive modulus of 403.98 +/- 19.53 MPa and a compressive strength of 9.83 +/- 0.94 MPa, which are in the range of human trabecular bone. Furthermore, the heparinized chitosan/PLAGA scaffolds had an interconnected porous structure with a total pore volume of 30.93 +/- 0.90% and a median pore size of 172.33 +/- 5.89 mum. The effect of immobilized heparin on osteoblast-like MC3T3-E1 cell growth was investigated. MC3T3-E1 cells proliferated three dimensionally throughout the porous structure of the scaffolds. Heparinized chitosan/PLAGA scaffolds with low heparin loading (1.7 microg/scaffold) were shown to be capable of stimulating MC3T3-E1 cell proliferation by MTS assay and cell differentiation as evidenced by elevated osteocalcin expression when compared with nonheparinized chitosan/PLAGA scaffold and chitosan/PLAGA scaffold with high heparin loading (14.1 microg/scaffold). This study demonstrated the potential of functionalizing chitosan/PLAGA scaffolds via heparinization with improved cell functions for bone tissue engineering applications.

Catalytic acetoxylation of lactic acid to 2-acetoxypropionic acid, en route to acrylic acid

NARCIS (Netherlands)

Beerthuis, R.; Granollers, M.; Brown, D.R.; Salavagione, H.J.; Rothenberg, G.; Shiju, N.R.

2015-01-01

We present an alternative synthetic route to acrylic acid, starting from the platform chemical lactic acid and using heterogeneous catalysis. To improve selectivity, we designed an indirect dehydration reaction that proceeds via acetoxylation of lactic acid to 2-acetoxypropionic acid. This

Improved mechanical properties of hydroxyapatite whisker-reinforced poly(L-lactic acid) scaffold by surface modification of hydroxyapatite.

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Fang, Zhou; Feng, Qingling

2014-02-01

To improve the mechanical properties of porous hydroxyapatite/poly(L-lactic acid) (HA/PLLA) composites, HA whiskers with high crystallinity and high aspect ratio were synthesized. HA whiskers were modified with γ-aminopropyltriethoxysilane (APTES) to improve the interface between HA whiskers and PLLA. The composite scaffold consists of a porous PLLA matrix with HA whiskers distributed homogeneously. The morphology and the distributions of pore sizes of PLLA scaffold was not influenced by introducing HA whiskers, while the mechanical properties were improved. Both the compressive strength and compressive modulus were increased with the weight ratio of APTES-modified HA whiskers up to 30 wt.%, but only up to 15 wt.% for non-modified HA whiskers. With more than 15 wt.% HA whiskers, the mechanical properties of HA/PLLA scaffold were better improved with APTES-modified HA whiskers than non-modified. The HA whisker/PLLA scaffold with high porosity and improved mechanical properties is attractive in the application of tissue engineering. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of novel nano-biocomposite antioxidant films based on poly (lactic acid) and thymol for active packaging.

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Ramos, Marina; Jiménez, Alfonso; Peltzer, Mercedes; Garrigós, María C

2014-11-01

Novel nano-biocomposite films based on poly (lactic acid) (PLA) were prepared by incorporating thymol, as the active additive, and modified montmorillonite (D43B) at two different concentrations. A complete thermal, structural, mechanical and functional characterization of all nano-biocomposites was carried out. Thermal stability was not significantly affected by the addition of thymol, but the incorporation of D43B improved mechanical properties and reduced the oxygen transmission rate by the formation of intercalated structures, as suggested by wide angle X-ray scattering patterns and transmission electron microscopy images. The addition of thymol decreased the PLA glass transition temperature, as the result of the polymer plasticization, and led to modification of the elastic modulus and elongation at break. Finally, the amount of thymol remaining in these formulations was determined by liquid chromatography (HPLC-UV) and the antioxidant activity by the DPPH spectroscopic method, suggesting that the formulated nano-biocomposites could be considered a promising antioxidant active packaging material. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Influence of Chemical Surface Modification of Kenaf Fiber using Hydrogen Peroxide on the Mechanical Properties of Biodegradable Kenaf Fiber/Poly(Lactic Acid Composites

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Nur Inani Abdul Razak

2014-03-01

Full Text Available Bleaching treatment of kenaf fiber was performed in alkaline medium containing hydrogen peroxide solution maintained at pH 11 and 80 °C for 60 min. The bleached kenaf fiber was analyzed using Fourier Transform Infrared (FTIR and X-ray Diffraction (XRD analysis. The bleached kenaf fiber was then compounded with poly-(lactic acid (PLA via a melt blending method. The mechanical (tensile, flexural and impact performance of the product was tested. The fiber treatment improved the mechanical properties of PLA/bleached kenaf fiber composites. Scanning electron micrograph (SEM morphological analysis showed improvement of the interfacial adhesion between the fiber surface and polymer matrix.

Lactic acid production from xylose by Geobacillus stearothermophilus strain 15

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Kunasundari, B.; Naresh, S.; Chu, J. E.

2017-09-01

Lactic acid is an important compound with a wide range of industrial applications. The present study tested the efficiency of xylose, as a sole carbon source to be converted to lactic acid by Geobacillus stearothermophilus strain 15. To the best of our knowledge, limited information is available on the directed fermentation of xylose to lactic acid by this bacterium. The effects of different parameters such as temperature, pH, incubation time, agitation speed, concentrations of nitrogen and carbon sources on the lactic acid production were investigated statistically. It was found that the bacterium exhibited poor assimilation of xylose to lactic acid. Temperature, agitation rate and incubation time were determined to improve the lactic acid production slightly. The highest lactic acid yield obtained was 8.9% at 45°C, 300 RPM, 96 h, pH of 6.0 with carbon and nitrogen source concentrations were fixed at 5% w/v.

Synthesis and characterization of magnesium gluconate contained poly(lactic-co-glycolic acid)/chitosan microspheres

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Rahman, Shekh M. [Department of Chemical, Biological and Bioengineering, North Carolina A& T State University, 1601 East Market Street, Greensboro, NC 27411 (United States); NSF Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A& T State University, Greensboro, NC 27411 (United States); Mahoney, Christopher [Department of Bioengineering, University of Pittsburgh, 4200 Fifth Avenue, Pittsburgh, PA 15250 (United States); Sankar, Jagannathan [NSF Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A& T State University, Greensboro, NC 27411 (United States); Department of Mechanical Engineering, North Carolina A& T State University, 1601 East Market Street, Greensboro, NC 27411 (United States); Marra, Kacey G. [NSF Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A& T State University, Greensboro, NC 27411 (United States); Department of Bioengineering, University of Pittsburgh, 4200 Fifth Avenue, Pittsburgh, PA 15250 (United States); Department of Plastic Surgery, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15250 (United States); McGowan Institute for Regenerative Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, PA 15250 (United States); Bhattarai, Narayan, E-mail: nbhattar@ncat.edu [Department of Chemical, Biological and Bioengineering, North Carolina A& T State University, 1601 East Market Street, Greensboro, NC 27411 (United States); NSF Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A& T State University, Greensboro, NC 27411 (United States)

2016-01-15

Graphical abstract: - Highlights: • Magnesium gluconate contained PLGA/chitosan microspheres were fabricated. • In vitro release of magnesium ions was performed using Xylidyl Blue assay. • Chitosan coated PLGA can significantly control the release of magnesium ions. • Cellular compatibility was tested using adipose-derived stem cells and PC12 cells. • The cells encounter acceptably low levels of damage in contact with microspheres. - Abstract: The goal of this study was to fabricate and investigate the chitosan coated poly(lactic-co-glycolic acid) (PLGA) microspheres for the development of controlled release magnesium delivery system. PLGA based microspheres are ideal vehicles for many controlled release drug delivery applications. Chitosan is a naturally occurring biodegradable and biocompatible polysaccharide, which can coat the surface of PLGA to alter the release of drugs. Magnesium gluconate (MgG) was encapsulated in the PLGA and PLGA/chitosan microspheres by utilizing the double emulsion solvent evaporation technique for controlled release study. The microspheres were tested with respect to several physicochemical and biological properties, including morphology, chemical structure, chitosan adsorption efficiency, magnesium encapsulation efficiency, in vitro release of magnesium ions, and cellular compatibility using both human adipose-derived stem cells (ASCs) and PC12 cells. Chitosan coated PLGA microspheres can significantly control the release of magnesium ions compared to uncoated PLGA microspheres. Both coated and uncoated microspheres showed good cellular compatibility.

Softened and flexible biodegradable poly(lactic acid) and its electromechanical properties for actuator application.

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Thummarungsan, Natlita; Pattavarakorn, Datchanee; Sirivat, Anuvat

2016-12-01

Poly (lactic acid) (PLA) is a biodegradable polymer with high stiffness presenting a limitation for using in actuator applications. Adding a plasticizer is one way to solve this problem to enhance flexibility and improve electromechanical properties of pristine PLA. In this work, the PLA films were prepared via a simple solvent casting method. The influences of plasticizer type and electric field strength on electromechanical behavior of PLA films were investigated by the melt rheometer and bending measurement. For the PLA films filled with dibutyl phthalate (DBP), the storage modulus, G', immediately increased towards its steady state and rapidly recovered to its original value with and without electric field, respectively, which can be referred to a reversible system. On the other hand, the PLA film with Tween 20 processed the highest ∆G׳/G׳0 of 1.34 due to the available amount of polarized groups. In the bending measurement, the dielectrophoresis forces of plasticized PLA films were found to increase with increasing electric field where the deflections occurred towards anode side as the polarized groups generated negative charges. The DBP_PLA1.5D film exhibited the greatest bending and dielectrophoresis force. Thus, the biodegradable PLA along with DBP combine to have a great potential towards actuator application. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

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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.

All Biomass and UV Protective Composite Composed of Compatibilized Lignin and Poly (Lactic-acid)

Science.gov (United States)

Kim, Youngjun; Suhr, Jonghwan; Seo, Hee-Won; Sun, Hanna; Kim, Sanghoon; Park, In-Kyung; Kim, Soo-Hyun; Lee, Youngkwan; Kim, Kwang-Jin; Nam, Jae-Do

2017-03-01

Utilization of carbon-neutral biomass became increasingly important due to a desperate need for carbon reduction in the issue of global warming in light of replacing petroleum-based materials. We used lignin, which was an abundant, low cost, and non-food based biomass, for the development of all biomass-based films and composites through reactive compatibilization with poly (lactic-acid) (PLA). Using a facile and practical route, the hydrophilic hydroxyl groups of lignin were acetylated to impose the compatibility with PLA. The solubility parameter of the pristine lignin at 26.3 (J/cm3)0.5 was altered to 20.9 (J/cm3)0.5 by acetylation allowing the good compatibility with PLA at 20.2 (J/cm3)0.5. The improved compatibility of lignin and PLA provided substantially decreased lignin domain size in composites (12.7 μm), which subsequently gave transparent and UV-protection films (visual transmittance at 76% and UV protection factor over 40). The tensile strength and elongation of the developed composite films were increased by 22% and 76%, respectively, and the biobased carbon content was confirmed as 96 ± 3%. The developed PLA/lignin composites provided 100% all-biomass contents and balanced optical and mechanical properties that could broaden its eco-friendly applications in various industries.

Mechanical, thermal and morphological properties of poly(lactic acid)/ethylene-butyl acrylate copolymer nanocomposites

Science.gov (United States)

Wacharawichanant, S.; Hoysang, P.; Ratchawong, S.

2017-07-01

This paper reports a melt blend of poly(lactic acid) (PLA)/ethylene-butyl acrylate copolymer (EBAC) with organoclay content at 3 phr. The mechanical, thermal and morphological properties of PLA/EBAC blends and nanocomposites were investigated. The morphological analysis revealed EBAC phase dispersed as a spherical domain in PLA matrix and the domain size of EBAC dispersed phase increased with increasing EBAC content. The addition of organoclay could improve the miscibility of PLA/EBAC blends due to the decrease of domain size of EBAC dispersed phase. The mechanical properties indicated that the strain at break and impact strength of PLA increased when added EBAC, but Young’s modulus and tensile strength decreased. Storage modulus increased with the addition of organoclay to the PLA/EBAC blends. The thermal properties found that the incorporation of organoclay in the PLA/EBAC blends did not effect on the glass transition temperature and melting temperature values relative to PLA. The degradation temperature of PLA improved with the addition of EBAC. This indicated that EBAC has more thermal stability and degradation temperature than PLA. From X-ray diffraction patterns displayed the characteristic peak in PLA/EBAC/organoclay nanocomposites appeared at the lower angle, which indicated the dispersed clay is intercalated in the polymer matrix. However, second-order diffraction peak appeared at the higher angle indicated that there was partially the conventional composite.

Thermal property and assessment of biocompatibility of poly(lactic-co-glycolic) acid/graphene nanocomposites

International Nuclear Information System (INIS)

Adhikari, Ananta R.; Rusakova, Irene; Chu, Wei-Kan; Haleh, Ardebili; Luisi, Jonathan; Panova, Neli I.; Laezza, Fernanda

2014-01-01

Polymer-matrix nanocomposites based on Poly(lactic-co-glycolic) acid (PLGA) and Graphene platelets (GNPs) were studied. GNPs, nanomaterials with a 2D flat surface, were chosen with or without chemical modification in PLGA/GNP nanocomposites and their microstructure, thermal property, and their compatibility as scaffolds for cell growth were investigated. PLGA/GNP nanocomposites (0, 1, and 5 wt. % of GNPs) were prepared using a solution based technique. Transmission electron microscopy, X-ray diffraction, Differential scanning calorimeter, and Thermogravimetric analyzer were used to analyze morphology and thermal properties. This work demonstrated the role of GNPs flat surface to provide a favorable platform resulting in an enhanced PLGA crystallization. Functionalized GNPs suppress both the thermal stability and the crystallization of PLGA. Finally, to determine the potential usefulness of these scaffolds for biomedical applications, mammalian cells were cultured on various PLGA/GNP nanocomposites (0, 1, and 5 wt. % GNPs). 1 wt. % PLGA/GNP nanocomposites showed better biocompatibility for cell growth with/without graphenes functionalization compared to pure PLGA and 5 wt. % PLGA/GNP. The function of GNPs in PLGA/GNPs (1 wt. %) composites is to provide a stage for PLGA crystallization where cell growth is favored. These results provide strong evidence for a new class of materials that could be important for biomedical applications

Electron transport chains of lactic acid bacteria

NARCIS (Netherlands)

Brooijmans, R.J.W.

2008-01-01

Lactic acid bacteria are generally considered facultative anaerobic obligate fermentative bacteria. They are unable to synthesize heme. Some lactic acid bacteria are unable to form menaquinone as well. Both these components are cofactors of respiratory (electron transport) chains of prokaryotic

Mechanical properties and dual drug delivery application of poly(lactic-co-glycolic acid) scaffolds fabricated with a poly(β-amino ester) porogen.

Science.gov (United States)

Clark, Amanda; Milbrandt, Todd A; Hilt, J Zach; Puleo, David A

2014-05-01

Polymeric scaffolds that are biocompatible and biodegradable are widely used for tissue engineering applications. Scaffolds can be further enhanced by enabling the release of one or more drugs to stimulate regeneration or for the treatment of a specific disease or condition. In this study, poly(lactic-co-glycolic acid) (PLGA) microspheres were mixed with poly(β-amino ester) (PBAE) particles to create novel hybrid scaffolds capable of dual release of drug and growth factor. Fast-degrading PBAE particles loaded with the drug ketoprofen acted as porogens that provided a rapid 12h release. The PLGA microspheres were loaded with a growth factor, bone morphogenetic protein 2, and fused together around the porogens to create a slow-degrading matrix that provided sustained release lasting 70days. Drug release was further tailored by varying the amount of porogen added to the scaffold. Bioactivity measurements demonstrated that the scaffold fabrication technique did not damage the drug or protein. The compressive modulus was affected by the amount of porogen added, extending from 50 to 111MPa for loadings from 60 to 40% PBAE, and after 5days of degradation, it decreased to 0.6 to 1.1kPa when the porogen was gone. PLGA containing a quick-degrading porogen can be used to release two drugs while developing a porous microarchitecture for cell ingrowth with in a matrix capable of maintaining a compressive modulus applicable for soft tissue implants. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of Extrusion on the Mechanical and Rheological Properties of a Reinforced Poly(Lactic Acid): Reprocessing and Recycling of Biobased Materials.

Science.gov (United States)

Peinado, Víctor; Castell, Pere; García, Lidia; Fernández, Ángel

2015-10-19

The aim of this research paper is to study the behaviour of a common used biopolymer (Poly(Lactic Acid) (PLA)) after several reprocesses and how two different types of additives (a melt strength enhancer and a nanoadditive) affect its mechanical and rheological properties. Systematic extraction of extrudate samples from a twin-screw compounder was done in order to study the effect in the properties of the reprocessed material. Detailed rheological tests on a capillary rheometer as well as mechanical studies on a universal tensile machine after preparation of injected specimens were carried out. Results evidenced that PLA and reinforced PLA materials can be reprocessed and recycled without a remarkable loss in their mechanical properties. Several processing restrictions and specific phenomena were identified and are explained in the present manuscript.

Mechanical and degradation properties of biodegradable Mg strengthened poly-lactic acid composite through plastic injection molding.

Science.gov (United States)

Butt, Muhammad Shoaib; Bai, Jing; Wan, Xiaofeng; Chu, Chenglin; Xue, Feng; Ding, Hongyan; Zhou, Guanghong

2017-01-01

Full biodegradable magnesium alloy (AZ31) strengthened poly-lactic acid (PLA) composite rods for potential application for bone fracture fixation were prepared by plastic injection process in this work. Their surface/interfacial morphologies, mechanical properties and vitro degradation were studied. In comparison with untreated Mg rod, porous MgO ceramic coating on Mg surface formed by Anodizing (AO) and micro-arc-oxidation (MAO)treatment can significantly improve the interfacial binding between outer PLA cladding and inner Mg rod due to the micro-anchoring action, leading to better mechanical properties and degradation performance of the composite rods.With prolonging immersion time in simulated body fluid (SBF) solution until 8weeks, the MgO porous coating were corroded gradually, along with the disappearance of original pores and the formation of a relatively smooth surface. This resulted in a rapidly reduction in mechanical properties for corresponding composite rods owing to the weakening of interfacial binding capacity. The present results indicated that this new PLA-clad Mg composite rods show good potential biomedical applications for implants and instruments of orthopedic inner fixation. Copyright © 2016 Elsevier B.V. All rights reserved.

Morphology and In Vitro Behavior of Electrospun Fibrous Poly(D,L-lactic acid for Biomedical Applications

Directory of Open Access Journals (Sweden)

Toshihiro Inami

2013-01-01

Full Text Available This work describes the fabrication, optimization, and characterization of electrospun fibrous poly(D,L-lactic acid (PDLLA for biomedical applications. The influences of the polymer concentration of the electrospinning solution (5, 10, or 15 wt% and the solution flow rate (0.1, 0.5, 1.0, or 2.0 mL/h on the morphology of the obtained fibrous PDLLA were evaluated. The in vitro biocompatibility of two types of PDLLA, ester terminated PDLLA (PDLLA-R and carboxyl terminated PDLLA (PDLLA-COOH, was evaluated by monitoring apatite formation on samples immersed in Hanks’ balanced salt (HBS solution. 15 wt% polymer solution was the most beneficial for preparing a fibrous PDLLA structure. Meanwhile, no differences in morphology were observed for PDLLA prepared at various flow rates. Apatite precipitate is formed on both types of PDLLA only 1 day after immersion in HBS solution. After 7 days of immersion, PDLLA-COOH showed greater apatite formation ability compared with that of PDLLA-R, as measured by thin-film X-ray diffraction. The results indicated that the carboxyl group is effective for apatite precipitation in the body environment.

Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications.

Science.gov (United States)

Abdal-Hay, Abdalla; Hussein, Kamal Hany; Casettari, Luca; Khalil, Khalil Abdelrazek; Hamdy, Abdel Salam

2016-03-01

Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low hydrophilicity and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265±222 nm, which is remarkably higher than its pristine counterpart (650±180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11±1.5°) compared to that of pristine PLA (119.7±1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine. Copyright © 2015. Published by Elsevier B.V.

Characterization of lactic acid bacteria isolated from Algerian arid ...

African Journals Online (AJOL)

Diversity and density of lactic acid bacteria isolated from Algerian raw goats\\' milk in arid zones were studied by determination of morphological, cultural, physiological and biochemical characteristics. 206 lactic acid bacterial strains were isolated, with 115 of them belonging to lactic acid cocci and others to the genus, ...

Synergistic Effects of Nucleating Agents and Plasticizers on the Crystallization Behavior of Poly(lactic acid

Directory of Open Access Journals (Sweden)

Xuetao Shi

2015-01-01

Full Text Available The synergistic effect of nucleating agents and plasticizers on the thermal and mechanical performance of PLA nanocomposites was investigated with the objective of increasing the crystallinity and balancing the stiffness and toughness of PLA mechanical properties. Calcium carbonate, halloysite nanotubes, talc and LAK (sulfates were compared with each other as heterogeneous nucleating agents. Both the DSC isothermal and non-isothermal studies indicated that talc and LAK were the more effective nucleating agents among the selected fillers. Poly(D-lactic acid (PDLA acted also as a nucleating agent due to the formation of the PLA stereocomplex. The half crystallization time was reduced by the addition of talc to about 2 min from 37.5 min of pure PLA by the isothermal crystallization study. The dynamic mechanical thermal study (DMTA indicated that nanofillers acted as both reinforcement fillers and nucleating agents in relation to the higher storage modulus. The plasticized PLA studied by DMTA indicated a decreasing glass transition temperature with the increasing of the PEG content. The addition of nanofiller increased the Young’s modulus. PEG had the plasticization effect of increasing the break deformation, while sharply decreasing the stiffness and strength of PLA. The synergistic effect of nanofillers and plasticizer achieved the balance between stiffness and toughness with well-controlled crystallization.

Self-aggregated nanoparticles based on amphiphilic poly(lactic acid-grafted-chitosan copolymer for ocular delivery of amphotericin B

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Zhou WJ

2013-09-01

Full Text Available Wenjun Zhou,1 Yuanyuan Wang,2 Jiuying Jian,2 Shengfang Song1 1Department of Ophthalmology, Yongchuan Hospital, Chongqing Medical University, Chongqing, People’s Republic of China; 2College of Life Science, Chongqing Medical University, Chongqing, People’s Republic of China Background: The purpose of this study was to develop a self-aggregated nanoparticulate vehicle using an amphiphilic poly(lactic acid-grafted-chitosan (PLA-g-CS copolymer and to evaluate its potential for ocular delivery of amphotericin B. Methods: A PLA-g-CS copolymer was synthesized via a “protection-graft-deprotection” procedure and its structure was confirmed by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and X-ray diffraction spectra. Amphotericin B-loaded nanoparticles based on PLA-g-CS (AmB/PLA-g-CS were prepared by the dialysis method and characterized for particle size, zeta potential, and encapsulation efficiency. Studies of these AmB/PLA-g-CS nanoparticles, including their mucoadhesive strength, drug release properties, antifungal activity, ocular irritation, ocular pharmacokinetics, and corneal penetration were performed in vitro and in vivo. Results: Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and X-ray diffraction spectra showed that the PLA chains were successfully grafted onto chitosan molecules and that crystallization of chitosan was suppressed. The self-aggregated PLA-g-CS nanoparticles had a core-shell structure with an average particle size of approximately 200 nm and zeta potentials higher than 30 mV. Amphotericin B was incorporated into the hydrophobic core of the nanoparticles with high encapsulation efficiency. Sustained drug release from the nanoparticles was observed in vitro. The ocular irritation study showed no sign of irritation after instillation of the PLA-g-CS nanoparticles into rabbit eyes. The minimal inhibitory concentration of the AmB/PLA-g-CS nanoparticles showed antifungal

Sprayed microspheres of poly(lactic acid) obtained with calcium compounds

International Nuclear Information System (INIS)

Goncalves, Raquel P.; Picciani, Paulo H. de Souza; Dias, Marcos L.

2011-01-01

In this work PLLA and PDLA were synthesized using calcium methoxide (Ca(OMe) 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 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 μm via electro spray technique. (author)

The Melting Behavior and Thermal Stability of Green Poly(L-lactic acid) with N, N, N, N'-Tetra(benzoyl) Ethylene Diamine Tetraacetic Acid Dihydrazide

International Nuclear Information System (INIS)

Cai, Y.; Qiang Xu, Q.; Ren, L.; Zhao, L.

2015-01-01

The thermal properties of green poly(L-lactic acid) (PLLA) with N, N, N, N'-tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide (NA) at different conditions were investigated. The melting behavior of PLLA/NA sample after isothermal crystallization at 100 degree C showed that the low-temperature melting peak shifted to high temperature with increasing of crystallization time. However, the high-temperature melting peak did not show any change. Meantime, the melting enthalpy of cold crystallization was higher than that of hot crystallization, and the difference between cold crystallization and hot crystallization increased from 0.31 J/g to 0.89 J/g with increasing of crystallization time. Heating or cooling rate affected the melting behavior of PLLA, the low-temperature and high-temperature melting peak shifted to low temperature with increasing of rate, and the ratio of melting peak area between low-temperature melting peak and high-temperature melting peak decreased. Thermal stability of PLLA/NA indicated that PLLA/NA only exhibited one decomposition stage as decomposition of PLLA. (author)

The effect of lactic acid bacteria on cocoa bean fermentation.

Science.gov (United States)

Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

2015-07-16

Cocoa beans (Theobroma cacao L.) are the raw material for chocolate production. Fermentation of cocoa pulp by microorganisms is crucial for developing chocolate flavor precursors. Yeasts conduct an alcoholic fermentation within the bean pulp that is essential for the production of good quality beans, giving typical chocolate characters. However, the roles of bacteria such as lactic acid bacteria and acetic acid bacteria in contributing to the quality of cocoa bean and chocolate are not fully understood. Using controlled laboratory fermentations, this study investigated the contribution of lactic acid bacteria to cocoa bean fermentation. Cocoa beans were fermented under conditions where the growth of lactic acid bacteria was restricted by the use of nisin and lysozyme. The resultant microbial ecology, chemistry and chocolate quality of beans from these fermentations were compared with those of indigenous (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii, Kluyveromyces marxianus and Saccharomyces cerevisiae, the lactic acid bacteria Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in control fermentations. In fermentations with the presence of nisin and lysozyme, the same species of yeasts and acetic acid bacteria grew but the growth of lactic acid bacteria was prevented or restricted. These beans underwent characteristic alcoholic fermentation where the utilization of sugars and the production of ethanol, organic acids and volatile compounds in the bean pulp and nibs were similar for beans fermented in the presence of lactic acid bacteria. Lactic acid was produced during both fermentations but more so when lactic acid bacteria grew. Beans fermented in the presence or absence of lactic acid bacteria were fully fermented, had similar shell weights and gave acceptable chocolates with no differences

Lactic acid Production with in situ Extraction in Membrane Bioreactor

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Hamidreza Ghafouri Taleghani

2017-01-01

Full Text Available Background and Objective: Lactic acid is widely used in the food, chemical and pharmaceutical industries. The major problems associated with lactic acid production are substrate and end-product inhibition, and by-product formation. Membrane technologyrepresents one of the most effective processes for lactic acid production. The aim of this work is to increase cell density and lactic acid productivity due to reduced inhibition effect of substrate and product in membrane bioreactor.Material and Methods: In this work, lactic acid was produced from lactose in membrane bioreactor. A laboratory scale membrane bioreactor was designed and fabricated. Five types of commercial membranes were tested at the same operating conditions (transmembrane pressure: 500 KPa and temperature: 25°C. The effects of initial lactose concentration and dilution rate on biomass growth, lactic acid production and substrate utilization were evaluated.Results and Conclusion: The high lactose retention of 79% v v-1 and low lactic acid retention of 22% v v-1 were obtained with NF1 membrane; therefore, this membrane was selected for membrane bioreactor. The maximal productivity of 17.1 g l-1 h-1 was obtainedwith the lactic acid concentration of 71.5 g l-1 at the dilution rate of 0.24 h−1. The maximum concentration of lactic acid was obtained at the dilution rate of 0.04 h−1. The inhibiting effect of lactic acid was not observed at high initial lactose concentration. The critical lactose concentration at which the cell growth severely hampered was 150 g l-1. This study proved that membrane bioreactor had great advantages such as elimination of substrate and product inhibition, high concentration of process substrate, high cell density,and high lactic acid productivity.Conflict of interest: There is no conflict of interest.

Hyaluronic acid/poly(lactic-co-glycolic acid) core/shell fiber meshes loaded with epigallocatechin-3-O-gallate as skin tissue engineering scaffolds.

Science.gov (United States)

Lee, Eun Ji; Lee, Jong Ho; Jin, Linhua; Jin, Oh Seong; Shin, Yong Cheol; Sang, Jin Oh; Lee, Jaebeom; Hyon, Suong-Hyu; Han, Dong-Wook

2014-11-01

In this study, hyaluronic acid (HA)/poly(lactic-co-glycolic acid, PLGA) core/shell fiber meshes loaded with epigallocatechin-3-O-gallate (EGCG) (HA/PLGA-E) for application to tissue engineering scaffolds for skin regeneration were prepared via coaxial electrospinning. Physicochemical properties of HA/PLGA-E core/shell fiber meshes were characterized by SEM, Raman spectroscopy, contact angle, EGCG release profiling and in vitro degradation. Biomechanical properties of HA/PLGA-E meshes were also investigated by a tensile strength test. SEM images showed that HA/PLGA-E fiber meshes had a three-dimensional interconnected pore structure with an average fiber diameter of about 1270 nm. Raman spectra revealed that EGCG was uniformly dispersed in the PLGA shell of meshes. HA/PLGA-E meshes showed sustained EGCG release patterns by controlled diffusion and PLGA degradation over 4 weeks. EGCG loading did not adversely affect the tensile strength and elastic modulus of HA/PLGA meshes, while increased their hydrophilicity and surface energy. Attachment of human dermal fibroblasts on HA/PLGA-E meshes was appreciably increased and their proliferation was steadily retained during the culture period. These results suggest that HA/PLGA-E core/shell fiber meshes can be potentially used as scaffolds supporting skin regeneration.

Lactic acid fermentation from refectory waste: Factorial design analysis

African Journals Online (AJOL)

Yomi

2012-04-12

Apr 12, 2012 ... method. At the end of the fermentation process, lactic acid exists in the complex medium of fermentation broth that contains whey proteins, biomass, salts and other impurities. Lactic acid is then recovered from this complex medium. Since the high cost of lactic acid purification process limits the utilization of ...

The effect of poly (lactic-co-glycolic) acid composition on the mechanical properties of electrospun fibrous mats

DEFF Research Database (Denmark)

Liu, Xiaoli; Aho, Johanna; Baldursdottir, Stefania G.

2017-01-01

The aim of this study was to investigate the influence of polymer molecular structure on the electrospinnability and mechanical properties of electrospun fibrous mats (EFMs). Polymers with similar molecular weight but different composition ratios (lactic acid (LA) and glycolic acid (GA)) were dis...

Comparative analysis method of permanent metallic stents (XIENCE) and bioresorbable poly-L-lactic (PLLA) scaffolds (Absorb) on optical coherence tomography at baseline and follow-up

NARCIS (Netherlands)

T. Nakatani (Tomoya); Y. Sotomi (Yohei); Y. Ishibashi (Yuki); M.J. Grundeken (Maik); H. Tateishi (Hiroki); E. Tenekecioglu (Erhan); Y. Zeng (Yaping); P. Suwannasom (Pannipa); E.S. Regar (Eveline); M. Radu (Maria); L. Räber (Lorenz); H.G. Bezerra (Hiram); M.A. Costa (Marco); Fitzgerald, P. (Peter); F. Prati (Francesco); R.A. Costa (Ricardo); J. Dijkstra (Jouke); T. Kimura (Takeshi); K. Kozuma (Ken); K. Tanabe (Kengo); T. Akasaka (Takashi); C. di Mario (Carlo); P.W.J.C. Serruys (Patrick); Y. Onuma (Yoshinobu); G. Guagliumi (Giulio)

2016-01-01

textabstractAims: Fully bioresorbable Absorb poly-L-lactic-acid (PLLA) scaffolds (Abbott Vascular, Santa Clara, CA, USA) are a novel approach for the treatment of coronary narrowing. Due to the translucency of the material (PLLA), the optical coherence tomography (OCT) measurement methods used in

Intensification of conversion of glucose to lactic acid : equilibria and kinetics for back extraction of lactic acid using trimethylamine

NARCIS (Netherlands)

Wasewar, Kailas L.; Heesink, A. Bert M.; Versteeg, Geert F.; Pangarkar, Vishwas G.

2004-01-01

Alamine 336 is an effective extractant for the recovery of lactic acid from aqueous solutions. An approach for regeneration and product recovery from such extracts is to back extract lactic acid with a water soluble, volatile tertiary amine such as trimethyl amine. Equilibrium data are presented

Intensification of conversion of glucose to lactic acid: equilibria and kinetics for back extraction of lactic acid using trimethylamine

NARCIS (Netherlands)

Wasewar, Kailas L.; Heesink, Albertus B.M.; Versteeg, Geert; Pangarkar, Vishwas G.

2004-01-01

Alamine 336 is an effective extractant for the recovery of lactic acid from aqueous solutions. An approach for regeneration and product recovery from such extracts is to back extract lactic acid with a water soluble, volatile tertiary amine such as trimethyl amine. Equilibrium data are presented

Engineering strategies aimed at control of acidification rate of lactic acid bacteria

DEFF Research Database (Denmark)

Martinussen, Jan; Solem, Christian; Holm, Anders Koefoed

2013-01-01

The ability of lactic acid bacteria to produce lactic acid from various sugars plays an important role in food fermentations. Lactic acid is derived from pyruvate, the end product of glycolysis and thus a fast lactic acid production rate requires a high glycolytic flux. In addition to lactic acid......, alternative end products - ethanol, acetic acid and formic acid - are formed by many species. The central role of glycolysis in lactic acid bacteria has provoked numerous studies aiming at identifying potential bottleneck(s) since knowledge about flux control could be important not only for optimizing food...

Synthesis and characterization of poly lactic acid and multiwall carbon nano-tubes mixtures

Science.gov (United States)

Kumar LG, Santhosh; del A. Cardona, Rocío; Berríos-Soto, Melvin; Santiago-Avilés, Jorge J.

2011-10-01

The motivation for this study is to reproduce processing conditions which lead to the formation of photo or photoinduced thermal actuation, combined with inexpensive, environmentally friendly (easily degradable) materials. Commercially available polymer, poly lactic acid (PLA), was used in our studies. PLA is a well know biodegradable polymer naturally obtained from corn. PLA was received as a solid resin in pellet form and dissolved in 1:3 acetone/chloroform solutions, to achieve the proper electrospinning kinematic viscosity. Once in the liquid phase, the material was mixed with commercially available multi-walled carbon nanotubes (MWCNTs) at varying concentrations and dispersed by severe sonication. The mixtures was electrospun at room temperature using a home built electrospinning apparatus capable of depositing randomly oriented fiber mats or oriented fibers onto different substrates, ranging from oxidized silicon wafers, alumina squares or glass microscope slides. The fibers diameters and lengths are statistically distributed following a log-normal distribution and the mean and dispersion are controlled by spinning parameters. Once the fibers were electrospun, they were compositionally, morphologically and structurally characterized by thermal and gravimetric analysis (TGA/DTA), rheology, imaging using a focused Ion Beam Scanning Electron Microscope (IBSEM), and IR /Raman methodologies. These studies can be used to explore PLA-MWCNTs mixtures suitability in applications such as super-capacitor technology, which would enable us to pursue further research in this field, while focusing on improving the electro spinning conditions so as to be able to better anticipate fiber morphology to generate a consistent regime of fibers.

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.

In vitro degradation of nanoparticles prepared from polymers based on DL-lactide, glycolide and poly(ethylene oxide)

NARCIS (Netherlands)

Zweers, M.L.T.; Engbers, G.H.M.; Grijpma, Dirk W.; Feijen, Jan

2004-01-01

Nanoparticles of poly(DL-lactic acid) (PDLLA), poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene oxide)–PLGA diblock copolymer (PEO–PLGA) were prepared by the salting-out method. The in vitro degradation of PDLLA, PLGA and PEO–PLGA nanoparticles in PBS (pH 7.4) at 37 °C was studied. The

Vorinostat with Sustained Exposure and High Solubility in Poly(ethylene glycol)-b-poly(DL-lactic acid) Micelle Nanocarriers: Characterization and Effects on Pharmacokinetics in Rat Serum and Urine

Science.gov (United States)

Mohamed, Elham A.; Zhao, Yunqi; Meshali, Mahasen M.; Remsberg, Connie M.; Borg, Thanaa M.; Foda, Abdel Monem M.; Takemoto, Jody K.; Sayre, Casey; Martinez, Stephanie; Davies, Neal M.; Forrest, M. Laird

2015-01-01

The histone deacetylase inhibitor suberoylanilide hydroxamic acid, known as vorinostat, is a promising anti-cancer drug with a unique mode of action; however, it is plagued by low water solubility, low permeability, and suboptimal pharmacokinetics. In this study, poly(ethylene glycol)-b-poly(DL-lactic acid) (PEG-b-PLA) micelles of vorinostat were developed. Vorinostat’s pharmacokinetics in rats were investigated after intravenous (i.v.) (10 mg/kg) and oral (50 mg/kg) micellar administrations and compared to a conventional PEG400 solution and methylcellulose suspension. The micelles increased the aqueous solubility of vorinostat from 0.2 mg/ml to 8.15 ± 0.60 mg/ml and 10.24 ± 0.92 mg/ml at drug to nanocarrier ratios of 1:10 and 1:15, respectively. Micelles had nanoscopic mean diameters of 75.67 ± 7.57 nm and 87.33 ± 8.62 nm for 1:10 and 1:15 micelles, respectively, with drug loading capacities of 9.93 ± 0.21% and 6.91 ± 1.19 %, and encapsulation efficiencies of 42.74 ± 1.67% and 73.29 ± 4.78%, respectively. The micelles provided sustained exposure and improved pharmacokinetics characterized by a significant increase in serum half-life, area under curve, and mean residence time. The micelles reduced vorinostat clearance particularly after i.v. dosing. Thus, PEG-b-PLA micelles significantly improved the oral and intravenous pharmacokinetics and bioavailability of vorinostat, which warrants further investigation. PMID:22806441

Vorinostat with sustained exposure and high solubility in poly(ethylene glycol)-b-poly(DL-lactic acid) micelle nanocarriers: characterization and effects on pharmacokinetics in rat serum and urine.

Science.gov (United States)

Mohamed, Elham A; Zhao, Yunqi; Meshali, Mahasen M; Remsberg, Connie M; Borg, Thanaa M; Foda, Abdel Monem M; Takemoto, Jody K; Sayre, Casey L; Martinez, Stephanie E; Davies, Neal M; Forrest, M Laird

2012-10-01

The histone deacetylase inhibitor suberoylanilide hydroxamic acid, known as vorinostat, is a promising anticancer drug with a unique mode of action; however, it is plagued by low water solubility, low permeability, and suboptimal pharmacokinetics. In this study, poly(ethylene glycol)-b-poly(DL-lactic acid) (PEG-b-PLA) micelles of vorinostat were developed. Vorinostat's pharmacokinetics in rats was investigated after intravenous (i.v.) (10 mg/kg) and oral (p.o.) (50 mg/kg) micellar administrations and compared with a conventional polyethylene glycol 400 solution and methylcellulose suspension. The micelles increased the aqueous solubility of vorinostat from 0.2 to 8.15 ± 0.60 and 10.24 ± 0.92 mg/mL at drug to nanocarrier ratios of 1:10 and 1:15, respectively. Micelles had nanoscopic mean diameters of 75.67 ± 7.57 and 87.33 ± 8.62 nm for 1:10 and 1:15 micelles, respectively, with drug loading capacities of 9.93 ± 0.21% and 6.91 ± 1.19%, and encapsulation efficiencies of 42.74 ± 1.67% and 73.29 ± 4.78%, respectively. The micelles provided sustained exposure and improved pharmacokinetics characterized by a significant increase in serum half-life, area under curve, and mean residence time. The micelles reduced vorinostat clearance particularly after i.v. dosing. Thus, PEG-b-PLA micelles significantly improved the p.o. and i.v. pharmacokinetics and bioavailability of vorinostat, which warrants further investigation. Copyright © 2012 Wiley Periodicals, Inc.

Co-Deposition of a Hydrogel/Calcium Phosphate Hybrid Layer on 3D Printed Poly(Lactic Acid Scaffolds via Dip Coating: Towards Automated Biomaterials Fabrication

Directory of Open Access Journals (Sweden)

Matthias Schneider

2018-03-01

Full Text Available The article describes the surface modification of 3D printed poly(lactic acid (PLA scaffolds with calcium phosphate (CP/gelatin and CP/chitosan hybrid coating layers. The presence of gelatin or chitosan significantly enhances CP co-deposition and adhesion of the mineral layer on the PLA scaffolds. The hydrogel/CP coating layers are fairly thick and the mineral is a mixture of brushite, octacalcium phosphate, and hydroxyapatite. Mineral formation is uniform throughout the printed architectures and all steps (printing, hydrogel deposition, and mineralization are in principle amenable to automatization. Overall, the process reported here therefore has a high application potential for the controlled synthesis of biomimetic coatings on polymeric biomaterials.

[Modeling of lactic acid fermentation of leguminous plant juices].

Science.gov (United States)

Shurkhno, R A; Validov, Sh Z; Boronin, A M; Naumova, R P

2006-01-01

Lactic acid fermentation of leguminous plant juices was modeled to provide a comparative efficiency assessment of the previously selected strains of lactic acid bacteria as potential components of starter cultures. Juices of the legumes fodder galega, red clover, and alfalfa were subjected to lactic acid fermentation in 27 variants of experiment. Local strains (Lactobacillus sp. RS 2, Lactobacillus sp. RS 3, and Lactobacillus sp. RS 4) and the collection strain Lactobacillus plantarum BS 933 appeared the most efficient (with reference to the rate and degree of acidogenesis, ratio of lactic and acetic acids, and dynamics of microflora) in fermenting fodder galega juice; Lactobacillus sp. RS 1, Lactobacillus sp. RS 2, Lactobacillus sp. RS 3, Lactobacillus sp. RS 4, and L. plantarum BS 933 were the most efficient for red clover juice. Correction of alfalfa juice fermentation using the tested lactic acid bacterial strains appeared inefficient, which is explainable by its increased protein content and a low level of the acids produced during fermentation.

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

scanning calorimetry (DSC) measurements. The data obtained from the stretched samples within 70-90 degrees C showed that all of the formed crystals are disordered alpha' form with more compact chain packing than that of the cold crystallization. Upon stretching at 70 degrees C, the mesocrystal appears......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...... in strain-induced crystallization behavior of amorphous PLA within 70-90 degrees C can be attributed to the competition between chain orientation caused by stretching and chain relaxation. It was proposed that the strain-induced mesocrystal/crystal and the lamellae are formed from the mesophase originally...

Arginine- and Polyamine-Induced Lactic Acid Resistance in Neisseria gonorrhoeae.

Directory of Open Access Journals (Sweden)

Zheng Gong

Full Text Available Microbe-derived lactic acid protects women from pathogens in their genital tract. The purpose of this study was to determine lactic acid susceptibility of Neisseria gonorrhoeae, and identify potential acid resistance mechanisms present in this pathogen. Tested in vitro, lactic acid killed all 10 gonococcal strains analyzed in a low pH-dependent manner. Full inactivation occurred at pH 4.5. At low pH, lactic acid treatment resulted in the entry of the DNA-binding fluorochrome propidium iodide into the microbial cells, suggesting that hydrogen ions from lactic acid compromise the integrity of the bacterial cell wall/membrane. Most likely, hydrogen ions also inactivate intracellular proteins since arginine rendered significant protection against lactic acid presumably through action of the gonococcal arginine decarboxylase, an enzyme located in the bacterial cytoplasm. Surprisingly, arginine also lessened lactic acid-mediated cell wall/membrane disruption. This effect is probably mediated by agmatine, a triamine product of arginine decarboxylase, since agmatine demonstrated a stronger protective effect on GC than arginine at equal molar concentration. In addition to agmatine, diamines cadaverine and putrescine, which are generated by bacterial vaginosis-associated microbes, also induced significant resistance to lactic acid-mediated GC killing and cell wall/membrane disruption. These findings suggest that the arginine-rich semen protects gonococci through both neutralization-dependent and independent mechanisms, whereas polyamine-induced acid resistance contributes to the increased risk of gonorrhea in women with bacterial vaginosis.

From Nanofibrillar to Nanolaminar Poly(butylene succinate): Paving the Way to Robust Barrier and Mechanical Properties for Full-Biodegradable Poly(lactic acid) Films.

Science.gov (United States)

Xie, Lan; Xu, Huan; Chen, Jing-Bin; Zhang, Zi-Jing; Hsiao, Benjamin S; Zhong, Gan-Ji; Chen, Jun; Li, Zhong-Ming

2015-04-22

The traditional approach toward barrier property enhancement of poly(lactic acid) (PLA) is the incorporation of sheet-like fillers such as nanoclay and graphene, unfortunately leading to the sacrificed biocompatibility and degradability. Here we unveil the first application of a confined flaking technique to establish the degradable nanolaminar poly(butylene succinate) (PBS) in PLA films based on PLA/PBS in situ nanofibrillar composites. The combination of high pressure (10 MPa) and appropriate temperature (160 °C) during the flaking process desirably enabled sufficient deformation of PBS nanofibrils and retention of ordered PLA channels. Particularly, interlinked and individual nanosheets were created in composite films containing 10 and 20 wt % PBS, respectively, both of which presented desirable alignment and large width/thickness ratio (nanoscale thickness with a width of 428±13.1 and 76.9±8.2 μm, respectively). With the creation of compact polymer "nano-barrier walls", a dramatic decrease of 86% and 67% in the oxygen permeability coefficient was observed for the film incorporated with well-organized 20 wt % PBS nanosheets compared to pure PLA and pure PBS (1.4 and 0.6×10(-14) cm3·cm·cm(-2)·s(-1)·Pa(-1)), respectively. Unexpectedly, prominent increases of 21% and 28% were achieved in the tensile strength and modulus of composite films loaded 20 wt % PBS nanosheets compared to pure PLA films, although PBS intrinsically presents poor strength and stiffness. The unusual combination of barrier and mechanical performances established in the fully degradable system represent specific properties required in packaging beverages, food and medicine.

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

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Sachiro eKakinoki

2014-07-01

Full Text Available We developed a microfibrous poly(L-lactic acid (PLLA nerve conduit with a three-layered structure to simultaneously enhance nerve regeneration and prevent adhesion of surrounding tissue. The inner layer was composed of PLLA microfiber containing 25% elastin-laminin mimetic protein (AG73-(VPGIG30 that promotes neurite outgrowth. The thickest middle layer was constructed of pure PLLA microfibers that impart the large mechanical stremgth to the conduit. A 10% poly(ethylene glycol was added to the outer layer to prevent the adhesion with the surrounding tissue. The AG73-(VPGIG30 composisting of an elastin-like repetitive sequence (VPGIG30 and a laminin-derived sequence (RKRLQVQLSIRT: AG73 was biosynthesized using Escherichia coli. The PLLA microfibrous conduits were fabricated using an electrospinning procedure. AG73-(VPGIG30 was successfully mixed in the PLLA microfibers, and the PLLA/AG73-(VPGIG30 microfibers were stable under physiological conditions. The PLLA/AG73-(VPGIG30 microfibers enhanced adhesion and neurite outgrowth of PC12 cells. The electrospun microfibrous conduit with a three-layered structure was implanted for bridging a 2.0-cm gap in the tibial nerve of a rabbit. Two months after implantation, no adhesion of surrounding tissue was observed, and the action potential was slightly improved in the nerve conduit with the PLLA/AG73-(VPGIG30 inner layer.

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

Science.gov (United States)

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

2014-07-01

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

The Effect of Emulation Formulation to Encapsulation of Fe3O4 Magnetic nanoparticle with Poly (Lactic Acid)

International Nuclear Information System (INIS)

Evi Yuliyanti; Sudaryanto; Mujamilah; Yoki Yulizar

2008-01-01

The research to study the effect of emulsion formulation to encapsulation Fe 3 O 4 magnetic nanoparticle with Poly(Lactic Acid) (PLA) has been done. Microemulsion by ultrasonic probe is used in encapsulation process and continued by solvent evaporation. Emulsion formulation has been varied by changing oil phase volume in the oil in water (o/w) emulsion system from 6 mL, 8 mL, 10 mL, 12 mL and 14 mL, whereas water phase volume is constant (55 mL). Sample characterization is carried on by Scanning Electron Microscope (SEM) to know the morphology and sample size. X-Ray Diffractometer (XRD) is used to identify the phase, Vibrating Sample Magnetometer (VSM) is used to measure magnetic saturation while Neutron Activation Analysis (NAA) is used to measure encapsulation percentage of Fe 3 O 4 with PLA. The smallest nanosphere is resulted by emulsion formulation (o/w) of 14/55 with the main sample size 382 nm. The maximum magnetic saturation of Fe 3 O 4 + PLA nanosphere is 2.556 emu/g and encapsulation percentage is 24.94 %. (author)

Influence of sodium chloride, pH, and lactic acid bacteria on anaerobic lactic acid utilization during fermented cucumber spoilage.

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Johanningsmeier, Suzanne D; Franco, Wendy; Perez-Diaz, Ilenys; McFeeters, Roger F

2012-07-01

Cucumbers are preserved commercially by natural fermentations in 5% to 8% sodium chloride (NaCl) brines. Occasionally, fermented cucumbers spoil after the primary fermentation is complete. This spoilage has been characterized by decreases in lactic acid and a rise in brine pH caused by microbial instability. Objectives of this study were to determine the combined effects of NaCl and pH on fermented cucumber spoilage and to determine the ability of lactic acid bacteria (LAB) spoilage isolates to initiate lactic acid degradation in fermented cucumbers. Cucumbers fermented with 0%, 2%, 4%, and 6% NaCl were blended into slurries (FCS) and adjusted to pH 3.2, 3.8, 4.3, and 5.0 prior to centrifugation, sterile-filtration, and inoculation with spoilage organisms. Organic acids and pH were measured initially and after 3 wk, 2, 6, 12, and 18 mo anaerobic incubation at 25 °C. Anaerobic lactic acid degradation occurred in FCS at pH 3.8, 4.3, and 5.0 regardless of NaCl concentration. At pH 3.2, reduced NaCl concentrations resulted in increased susceptibility to spoilage, indicating that the pH limit for lactic acid utilization in reduced NaCl fermented cucumbers is 3.2 or lower. Over 18 mo incubation, only cucumbers fermented with 6% NaCl to pH 3.2 prevented anaerobic lactic acid degradation by spoilage bacteria. Among several LAB species isolated from fermented cucumber spoilage, Lactobacillus buchneri was unique in its ability to metabolize lactic acid in FCS with concurrent increases in acetic acid and 1,2-propanediol. Therefore, L. buchneri may be one of multiple organisms that contribute to development of fermented cucumber spoilage. Microbial spoilage of fermented cucumbers during bulk storage causes economic losses for producers. Current knowledge is insufficient to predict or control these losses. This study demonstrated that in the absence of oxygen, cucumbers fermented with 6% sodium chloride to pH 3.2 were not subject to spoilage. However, lactic acid was degraded

A method for the determination of D(-)-lactic acid

NARCIS (Netherlands)

Hamer, C.J.A. van den; Elias, R.W.

A method for the determination of D(—)-lactic acid is described. An acetone powder from Escherichia coli B in the presence of methylene blue oxidizes D(—)-lactic specifically. Oxygen consumption in a Warburg apparatus was used as a measure of the D(—)-lactic acid.

Toughening of Poly(lactic acid and Thermoplastic Cassava Starch Reactive Blends Using Graphene Nanoplatelets

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Anibal Bher

2018-01-01

Full Text Available Poly(lactic acid (PLA was reactively blended with thermoplastic cassava starch (TPCS and functionalized with commercial graphene (GRH nanoplatelets in a twin-screw extruder, and films were produced by cast-film extrusion. Reactive compatibilization between PLA and TPCS phases was reached by introducing maleic anhydride and a peroxide radical during the reactive blending extrusion process. Films with improved elongation at break and toughness for neat PLA and PLA-g-TPCS reactive blends were obtained by an addition of GRH nanoplatelets. Toughness of the PLA-g-TPCS-GRH was improved by ~900% and ~500% when compared to neat PLA and PLA-g-TPCS, respectively. Crack bridging was established as the primary mechanism responsible for the improvement in the mechanical properties of PLA and PLA-g-TPCS in the presence of the nanofiller due to the high aspect ratio of GRH. Scanning electron microscopy images showed a non-uniform distribution of GRH nanoplatelets in the matrix. Transmittance of the reactive blend films decreased due to the TPCS phase. Values obtained for the reactive blends showed ~20% transmittance. PLA-GRH and PLA-g-TPCS-GRH showed a reduction of the oxygen permeability coefficient with respect to PLA of around 35% and 50%, respectively. Thermal properties, molecular structure, surface roughness, XRD pattern, electrical resistivity, and color of the films were also evaluated. Biobased and compostable reactive blend films of PLA-g-TPCS compounded with GRH nanoplatelets could be suitable for food packaging and agricultural applications.

Cytocompatibility of Siloxane-Containing Vaterite/Poly(l-lactic acid) Composite Coatings on Metallic Magnesium.

Science.gov (United States)

Yamada, Shinya; Maeda, Hirotaka; Obata, Akiko; Lohbauer, Ulrich; Yamamoto, Akiko; Kasuga, Toshihiro

2013-12-12

Poly(l-lactic acid)-based films which include 60 wt % of vaterite (V) or siloxane-containing vaterite (SiV) were coated on a pure magnesium substrate, denoted by PLLA/V or PLLA/SiV, respectively, to suppress early corrosion and improve its cytocompatibility. Both coating films adhered to the Mg substrate with 2.3-2.8 MPa of tensile bonding strength. Soaking test for 7 days in α-modified minimum essential medium revealed that the morphological instability of the PLLA/V film caused a higher amount of Mg 2+ ion to be released from the coating sample. On the other hand, in the case of the coating with the PLLA/SiV film, no morphological change even after the soaking test was observed, owing to the suppression of the degradation rate. In cell culture tests, the proliferation of mouse osteoblast-like cell (MC3T3-E1) was significantly enhanced by both coatings, in comparison with the uncoated magnesium substrate. The cell morphology revealed that a few less-spread cells were observed on the PLLA/V film, while more elongated cells were done on the PLLA/SiV film. The cells on the PLLA/SiV film exhibited an extremely higher alkaline phosphatase activity after 21 days of incubation than that on the PLLA/V one. The PLLA/SiV film suppressed the early corrosion and enhanced cytocompatibility on metallic magnesium.

Cytocompatibility of Siloxane-Containing Vaterite/Poly(l-lactic acid Composite Coatings on Metallic Magnesium

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Shinya Yamada

2013-12-01

Full Text Available Poly(l-lactic acid-based films which include 60 wt % of vaterite (V or siloxane-containing vaterite (SiV were coated on a pure magnesium substrate, denoted by PLLA/V or PLLA/SiV, respectively, to suppress early corrosion and improve its cytocompatibility. Both coating films adhered to the Mg substrate with 2.3–2.8 MPa of tensile bonding strength. Soaking test for 7 days in α-modified minimum essential medium revealed that the morphological instability of the PLLA/V film caused a higher amount of Mg2+ ion to be released from the coating sample. On the other hand, in the case of the coating with the PLLA/SiV film, no morphological change even after the soaking test was observed, owing to the suppression of the degradation rate. In cell culture tests, the proliferation of mouse osteoblast-like cell (MC3T3-E1 was significantly enhanced by both coatings, in comparison with the uncoated magnesium substrate. The cell morphology revealed that a few less-spread cells were observed on the PLLA/V film, while more elongated cells were done on the PLLA/SiV film. The cells on the PLLA/SiV film exhibited an extremely higher alkaline phosphatase activity after 21 days of incubation than that on the PLLA/V one. The PLLA/SiV film suppressed the early corrosion and enhanced cytocompatibility on metallic magnesium.

Ultrasonic Monitoring of the Progress of Lactic Acid Fermentation

Science.gov (United States)

Masuzawa, Nobuyoshi; Kimura, Akihiro; Ohdaira, Etsuzo

2003-05-01

Promotion of lactic acid fermentation by ultrasonic irradiation has been attempted. It is possible to determine the progress of fermentation and production of a curd, i.e., yoghurt and or kefir, by measuring acidity using a pH meter. However, this method is inconvenient and indirect for the evaluation of the progress of lactic acid fermentation under anaerobic condition. In this study, an ultrasonic monitoring method for evaluating the progress of lactic acid fermentation was examined.

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

Poly(ester-anhydride):poly(beta-amino ester) micro- and nanospheres: DNA encapsulation and cellular transfection.

Science.gov (United States)

Pfeifer, Blaine A; Burdick, Jason A; Little, Steve R; Langer, Robert

2005-11-04

Poly(ester-anhydride) delivery devices allow flexibility regarding carrier dimensions (micro- versus nanospheres), degradation rate (anhydride versus ester hydrolysis), and surface labeling (through the anhydride functional unit), and were therefore tested for DNA encapsulation and transfection of a macrophage P388D1 cell line. Poly(l-lactic acid-co-sebacic anhydride) and poly(l-lactic acid-co-adipic anhydride) were synthesized through melt condensation, mixed with 25 wt.% poly(beta-amino ester), and formulated with plasmid DNA (encoding firefly luciferase) into micro- and nanospheres using a double emulsion/solvent evaporation technique. The micro- and nanospheres were then characterized (size, morphology, zeta potential, DNA release) and assayed for DNA encapsulation and cellular transfection over a range of poly(ester-anhydride) copolymer ratios. Poly(ester-anhydride):poly(beta-amino ester) composite microspheres (6-12 microm) and nanospheres (449-1031 nm), generated with copolymers containing between 0 and 25% total polyanhydride content, encapsulated plasmid DNA (>or=20% encapsulation efficiency). Within this polyanhydride range, poly(adipic anhydride) copolymers provided DNA encapsulation at an increased anhydride content (10%, microspheres; 10-25%, nanospheres) compared to poly(sebacic anhydride) copolymers (1%, microspheres and nanospheres) with cellular transfection correlating with the observed DNA encapsulation.

Batch fermentative production of lactic acid from green- sugarcane juices

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Liliana Serna Cock

2004-07-01

Full Text Available Juice from the CC85-92 variety of green (unburned sugar cane was tested as a suitable substrate in lactic-acid production. Fermentations were carried out with a homo-fermentative strain isolated from crops of the same variety of cane. Both the centrifugation pre-treatment and concentrated-nitrogen effects on substrate conversion, lactic-acid concentration and yield were evaluated. After a fermentation time of 48 h at 32° C with 5% of yeast extract as nitrogen source, 40,78 g/L of lactic-acid concentration, 0.58 g/g of product yield and 33% of substrate conversion were obtained. Centrifugation did not affect lactic acid production. Key words: Lactic acid, green sugar cane, Lactococcus lactis subs. lactis.

Poly (L-lactic acid) porous scaffold-supported alginate hydrogel with improved mechanical properties and biocompatibility.

Science.gov (United States)

Chu, Jiaqi; Zeng, Shaodong; Gao, Liyang; Groth, Thomas; Li, Zhiwen; Kong, Junchao; Zhao, Mingyan; Li, Lihua

2016-10-10

Polymer porous scaffolds and hydrogels have been separately employed and explored for a wide range of applications including cell encapsulation, drug delivery, and tissue engineering. In this study, a three-dimensional poly (L-lactic acid) (PLLA) scaffold with interconnected and homogeneously distributed pores was fabricated to support the alginate hydrogel (Alg). The gels were filled into the porous scaffold, which acted as an analogue of native extracellular matrix (ECM) for entrapment of cells within a support of predefined shape. The mechanical strength of the composite scaffold was characterized by compression testing. The chondrocyte behavior in the scaffold was determined by inverted microscopy, scanning electron microscopy (SEM) and MTT viability assay. The repair efficiency of such a composite scaffold was further investigated in dog spinal defects by histological evaluation after implantation for 4 weeks. Results showed that the composite scaffold possessed superior mechanical properties and hierarchical porous structure in comparison to pure Alg. Cell culture revealed that the cells presented a specific cartilage status in the composite scaffold in line with higher adherence and proliferation ratio. The histological analyses suggested that the composite scaffold substantially promotes its integration in the host tissue accompanied with a low inflammatory reaction and new tissue formation. The method thus provides a useful pathway for scaffold preparation that can simultaneously achieve suitable mechanical properties and good biocompatibility.

Patterning Multi-Nanostructured Poly(l-lactic acid) Fibrous Matrices to Manipulate Biomolecule Distribution and Functions.

Science.gov (United States)

Xiao, Wenwu; Li, Qingtao; He, Huimin; Li, Wenxiu; Cao, Xiaodong; Dong, Hua

2018-03-14

Precise manipulation of biomolecule distribution and functions via biomolecule-matrix interaction is very important and challenging for tissue engineering and regenerative medicine. As a well-known biomimetic matrix, electrospun fibers often lack the unique spatial complexity compared to their natural counterparts in vivo and thus cannot deliver fully the regulatory cues to biomolecules. In this paper, we report a facile and reliable method to fabricate micro- and nanostructured poly(l-lactic acid) (PLLA) fibrous matrices with spatial complexity by a combination of advanced electrospinning and agarose hydrogel stamp-based micropatterning. Specifically, advanced electrospinning is used to construct multi-nanostructures of fibrous matrices while solvent-loaded agarose hydrogel stamps are used to create microstructures. Compared with other methods, our method shows extreme simplicity and flexibility originated from the mono-/multi-spinneret conversion and limitless micropatterns of agarose hydrogel stamps. Three types of PLLA fibrous matrices including patterned nano-Ag/PLLA hybrid fibers, patterned bicompartment polyethylene terephthalate/PLLA fibers, and patterned hollow PLLA fibers are fabricated and their capability to manipulate biomolecule distribution and functions, that is, bacterial distribution and antibacterial performance, cell patterning and adhesion/spreading behaviors, and protein adsorption and delivery, is demonstrated in detail. The method described in our paper provides a powerful tool to restore spatial complexity in biomimetic matrices and would have promising applications in the field of biomedical engineering.

Efficacy of Poly-Lactic-Co-Glycolic Acid Micro- and Nanoparticles of Ciprofloxacin Against Bacterial Biofilms.

Science.gov (United States)

Thomas, Nicky; Thorn, Chelsea; Richter, Katharina; Thierry, Benjamin; Prestidge, Clive

2016-10-01

Bacterial biofilms are associated with a number of recurring infectious diseases and are a major cause for antibiotic resistance. Despite the broad use of polymeric microparticles and nanoparticles in biomedical research, it is not clear which particle size is more effective against biofilms. The purpose of this study was to evaluate the efficacy of sustained release poly-lactic-co-glycolic acid (PLGA) micro- and nanoparticles containing ciprofloxacin against biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. The PLGA particles were prepared by the double emulsion solvent evaporation method. The resulting microparticles (12 μm) and nanoparticles (300 nm) contained drug loads of 7.3% and 4.5% (wt/wt) ciprofloxacin, respectively. Drug release was complete within 1 week following comparable release profiles for both particle sizes. Micro- and nanoparticles demonstrated a similar in vitro antibiofilm performance against mature P aeruginosa and S aureus with marked differences between the 2 strains. The sustained release of ciprofloxacin from micro- and nanoparticles over 6 days was equally effective as the continuous treatment with ciprofloxacin solution over the same period resulting in the eradication of culturable S aureus suggesting that reformulation of ciprofloxacin as sustained release PLGA micro- and nanoparticles might be valuable formulation approaches for the treatment of biofilms. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Effect of clay content on morphology and processability of electrospun keratin/poly(lactic acid) nanofiber.

Science.gov (United States)

Isarankura Na Ayutthaya, Siriorn; Tanpichai, Supachok; Sangkhun, Weradesh; Wootthikanokkhan, Jatuphorn

2016-04-01

This research work has concerned the development of volatile organic compounds (VOCs) removal filters from biomaterials, based on keratin extracted from chicken feather waste and poly(lactic acid) (PLA) (50/50%w/w) blend. Clay (Na-montmorillonite) was also added to the blend solution prior to carrying out an electro-spinning process. The aim of this study was to investigate the effect of clay content on viscosity, conductivity, and morphology of the electrospun fibers. Scanning electron micrographs showed that smooth and bead-free fibers were obtained when clay content used was below 2 pph. XRD patterns of the electrospun fibers indicated that the clay was intercalated and exfoliated within the polymers matrix. Percentage crystallinity of keratin in the blend increased after adding the clay, as evidenced from FTIR spectra and DSC thermograms. Transmission electron micrographs revealed a kind of core-shell structure with clay being predominately resided within the keratin rich shell and at the interfacial region. Filtration performance of the electrospun keratin/PLA fibers, described in terms of pressure drop and its capability of removing methylene blue, were also explored. Overall, our results demonstrated that it was possible to improve process-ability, morphology and filtration efficiency of the electrospun keratin fibers by adding a suitable amount of clay. Copyright © 2016 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Residual Tensile Property of Plain Woven Jute Fiber/Poly(Lactic Acid) Green Composites during Thermal Cycling.

Science.gov (United States)

Katogi, Hideaki; Takemura, Kenichi; Akiyama, Motoki

2016-07-14

This study investigated the residual tensile properties of plain woven jute fiber reinforced poly(lactic acid) (PLA) during thermal cycling. Temperature ranges of thermal cycling tests were 35-45 °C and 35-55 °C. The maximum number of cycles was 10³ cycles. The quasi-static tensile tests of jute fiber, PLA, and composite were conducted after thermal cycling tests. Thermal mechanical analyses of jute fiber and PLA were conducted after thermal cycling tests. Results led to the following conclusions. For temperatures of 35-45 °C, tensile strength of composite at 10³ cycles decreased 10% compared to that of composite at 0 cycles. For temperatures of 35-55 °C, tensile strength and Young's modulus of composite at 10³ cycles decreased 15% and 10%, respectively, compared to that of composite at 0 cycles. Tensile properties and the coefficient of linear expansion of PLA and jute fiber remained almost unchanged after thermal cycling tests. From observation of a fracture surface, the length of fiber pull out in the fracture surface of composite at 10³ cycles was longer than that of composite at 0 cycles. Therefore, tensile properties of the composite during thermal cycling were decreased, probably because of the decrease of interfacial adhesion between the fiber and resin.

A Facile and Eco-friendly Route to Fabricate Poly(Lactic Acid) Scaffolds with Graded Pore Size.

Science.gov (United States)

Scaffaro, Roberto; Lopresti, Francesco; Botta, Luigi; Maio, Andrea; Sutera, Fiorenza; Mistretta, Maria Chiara; La Mantia, Francesco Paolo

2016-10-17

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of this new field of biomaterials research is due to the necessity to develop implants capable of mimicking the complex functionality of the various tissues, including a continuous change from one structure or composition to another. In this latter context, one topic of main interest concerns the design of appropriate scaffolds for bone-cartilage interface tissue. In this study, three-layered scaffolds with graded pore size were achieved by melt mixing poly(lactic acid) (PLA), sodium chloride (NaCl) and polyethylene glycol (PEG). Pore size distributions were controlled by NaCl granulometry and PEG solvation. Scaffolds were characterized from a morphological and mechanical point of view. A correlation between the preparation method, the pore architecture and compressive mechanical behavior was found. The interface adhesion strength was quantitatively evaluated by using a custom-designed interfacial strength test. Furthermore, in order to imitate the human physiology, mechanical tests were also performed in phosphate buffered saline (PBS) solution at 37 °C. The method herein presented provides a high control of porosity, pore size distribution and mechanical performance, thus offering the possibility to fabricate three-layered scaffolds with tailored properties by following a simple and eco-friendly route.

Fabrication and formation mechanism of poly (L-lactic acid ultrafine multi-porous hollow fiber by electrospinning

Directory of Open Access Journals (Sweden)

Q. Z. Yu

2013-01-01

Full Text Available Poly(L-lactic acid (PLLA ultrafine multi-porous hollow fibers are fabricated by electrospinning with methylene dichloride as solvent. The Kirkendall effect has been widely applied for the fabrication of hollow structure in metals and inorganic materials. In this study, a conceptual extension is proposed for the formation mechanism: the development of porous hollow fiber undergoes three stages. The initial stage is the generation of small voids or pits on the surface of the fiber via surface diffusion and phase separation; the second stage is the formation of multi-pores penetrating the core of the fiber through the interaction of Kirkendall effect, surface diffusion and phase separation; the third stage is dominated by surface diffusion of the core material along the pore surface. To explore the formation conditions, the factors including ambient temperature, relativity humidity (R. H., molecular weight and fiber diameter are studied. The longitudinal and cross sectional morphologies of these fibers are examined by scanning electron micrograph (SEM. The results show that the prerequisite for the formation of uniform porous hollow PLLA fibers include moderate ambient temperature (10~20°C and appropriate molecular weight for the PLLA, as well as the diameter of the fiber in the range of several micrometers to about 100 nanometers.

Eco-sustainable systems based on poly(lactic acid), diatomite and coffee grounds extract for food packaging.

Science.gov (United States)

Cacciotti, Ilaria; Mori, Stefano; Cherubini, Valeria; Nanni, Francesca

2018-06-01

In the food packaging sector many efforts have been (and are) devoted to the development of new materials in order to reply to an urgent market demand for green and eco-sustainable products. Particularly a lot of attention is currently devoted both to the use of compostable and biobased polymers as innovative and promising alternative to the currently used petrochemical derived polymers, and to the re-use of waste materials coming from agriculture and food industry. In this work, multifunctional eco-sustainable systems, based on poly(lactic acid) (PLA) as biopolymeric matrix, diatomaceous earth as reinforcing filler and spent coffee grounds extract as oxygen scavenger, were produced for the first time, in order to provide a simultaneous improvement of mechanical and gas barrier properties. The influence of the diatomite and the spent coffee grounds extract on the microstructural, mechanical and oxygen barrier properties of the produced films was deeply investigated by means of X-Ray diffraction (XRD), infrared spectroscopy (FT-IR, ATR), scanning electron microscopy (SEM), uniaxial tensile tests, O 2 permeabilimetry measurements. An improvement of both mechanical and oxygen barrier properties was recorded for systems characterised by the co-presence of diatomite and coffee grounds extract, suggesting a possible synergic effect of the two additives. Copyright © 2018 Elsevier B.V. All rights reserved.

Co-electrospun gelatin-poly(L-lactic acid) scaffolds: Modulation of mechanical properties and chondrocyte response as a function of composition

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Torricelli, Paola [Preclinical and Surgical Studies Laboratory, Codivilla Putti Research Institute, Rizzoli Orthopaedic Institute, via di Barbiano, 1/10, 40136 Bologna (Italy); Laboratory of Biocompatibility, Innovative Technologies and Advanced Therapies—Department Rizzoli Research, Innovation, Technology, via di Barbiano, 1/10, 40136 Bologna (Italy); Gioffrè, Michela; Fiorani, Andrea; Panzavolta, Silvia [Department of Chemistry “G. Ciamician” and National Consortium of Materials Science and Technology (INSTM, Bologna RU), University of Bologna (Italy); Gualandi, Chiara [Department of Chemistry “G. Ciamician” and National Consortium of Materials Science and Technology (INSTM, Bologna RU), University of Bologna (Italy); Advanced Mechanics and Materials—Interdepartmental Center for Industrial Research (AMM ICIR), University of Bologna (Italy); Fini, Milena [Preclinical and Surgical Studies Laboratory, Codivilla Putti Research Institute, Rizzoli Orthopaedic Institute, via di Barbiano, 1/10, 40136 Bologna (Italy); Laboratory of Biocompatibility, Innovative Technologies and Advanced Therapies—Department Rizzoli Research, Innovation, Technology, via di Barbiano, 1/10, 40136 Bologna (Italy); Focarete, Maria Letizia, E-mail: marialetizia.focarete@unibo.it [Department of Chemistry “G. Ciamician” and National Consortium of Materials Science and Technology (INSTM, Bologna RU), University of Bologna (Italy); Health Sciences and Technologies—Interdepartmental Center for Industrial Research (HST-ICIR) (Italy); Bigi, Adriana [Department of Chemistry “G. Ciamician” and National Consortium of Materials Science and Technology (INSTM, Bologna RU), University of Bologna (Italy)

2014-03-01

Bio-synthetic scaffolds of interspersed poly(L-lactic acid) (PLLA) and gelatin (GEL) fibers are fabricated by co-electrospinning. Tailored PLLA/GEL compositions are obtained and GEL crosslinking with genipin provides for the maintenance of good fiber morphology. Scaffold tensile mechanical properties are intermediate between those of pure PLLA and GEL and vary as a function of PLLA content. Primary human chondrocytes grown on the scaffolds exhibit good proliferation and increased values of the differentiation parameters, especially for intermediate PLLA/GEL compositions. Mineralization tests enable the deposition of a uniform layer of poorly crystalline apatite onto the scaffolds, suggesting potential applications involving cartilage as well as cartilage–bone interface tissue engineering. - Highlights: • Bio-synthetic scaffolds of PLLA and gelatin are produced by co-electrospinning. • Scaffolds with tailored PLLA–gelatin composition are fabricated. • PLLA/gelatin ratio controls scaffold mechanical properties and mineralization. • Chondrocyte proliferation and differentiation are modulated. • Scaffolds are suitable for cartilage–bone interface tissue engineering.

A pro-angiogenic degradable Mg-poly(lactic-co-glycolic acid) implant combined with rhbFGF in a rat limb ischemia model.

Science.gov (United States)

Bao, Hanmei; Lv, Feng; Liu, Tianjun

2017-12-01

Site-specific controlled release of exogenous angiogenic growth factors, such as recombinant human basic fibroblast growth factor (rhbFGF), has become a promising approach to improve peripheral vascular disease. Here, we have developed an implant composed of spiral magnesium (Mg) and a coating made using poly(lactic-co-glycolic acid) (PLGA) with encapsulated rhbFGF (Mg-PLGA-rhbFGF). The encapsulated protein could release continually for 4weeks with well preserved bioactivity. We compared the angiogenic effect produced by Mg-PLGA-rhbFGF with that of a PLGA implant loaded with rhbFGF (PLGA-rhbFGF). The incorporation of Mg in the implant raised the microclimate pH in the polymer, which preserved the stability of rhbFGF. Mg-PLGA-rhbFGF exhibited advantages over PLGA-rhbFGF implant in terms of a cytocompatibility evaluation. An in vivo angiogenesis test further confirmed the efficacy of released rhbFGF. HE, CD31 and α-SMA staining revealed that the controlled release of rhbFGF from the Mg-PLGA-rhbFGF implant was superior in promoting angiogenesis compared with that of the PLGA-rhbFGF implant. Four weeks post-implantation, the capillary density of the Mg-PLGA-rhbFGF group was significantly higher than that of the PLGA-rhbFGF, control and the normal group (pspiral magnesium and a coating made using poly(lactic-co-glycolic acid) (PLGA) with encapsulated rhbFGF (Mg-PLGA-rhbFGF). The preparation method does not involve any complex processes and results in a high encapsulation efficiency (approximately 100%). The degradation of metal Mg raise the microclimate pH in the PLGA polymer, which could well preserve the bioactivity of rhbFGF incorporated in the implant. Mg-PLGA-based, sustained local delivery of rhbFGF promotes post-ischemic angiogenesis and blood flow recovery in rat limb ischemic model. This work marks the first report for controlled release of rhbFGF in combination with metal Mg, and suggests potential therapeutic usefulness of Mg-PLGA-rhbFGF for tissue ischemia

Lactic acid fermentation of crude sorghum extract

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Samuel, W.A.; Lee, Y.Y.; Anthony, W.B.

1980-04-01

Crude extract from sweet sorghum supplemented with vetch juice was utilized as the carbohydrate source for fermentative production of lactic acid. Fermentation of media containing 7% (w/v) total sugar was completed in 60-80 hours by Lactobacillus plantarum, product yield averaging 85%. Maximum acid production rates were dependent on pH, initial substrate distribution, and concentration, the rates varying from 2 to 5 g/liter per hour. Under limited medium supplementation the lactic acid yield was lowered to 67%. The fermented ammoniated product contained over eight times as much equivalent crude protein (N x 6.25) as the original medium. Unstructured kinetic models were developed for cell growth, lactic acid formation, and substrate consumption in batch fermentation. With the provision of experimentally determined kinetic parameters, the proposed models accurately described the fermentation process. 15 references.

Lactic acid fermentation of cassava dough into agbelima.

Science.gov (United States)

Amoa-Awua, W K; Appoh, F E; Jakobsen, M

1996-08-01

The souring of cassava dough during fermentation into the fermented cassava meal, agbelima, was investigated. Four different types of traditional inocula were used to ferment the dough and increases in titrable acidity expressed as lactic acid from 0.31-0.38 to 0.78-0.91% (w/w) confirmed the fermentation to be a process of acidification. The microflora of all inocula and fermenting dough contained high counts of lactic acid bacteria, 10(8)-10(9) cfu/g in all inocula and 10(7)-10(8), 10(8)-10(9) and 10(9) cfu/g at 0, 24 and 48 h in all fermentations. Lactobacillus plantarum was the dominant species of lactic acid bacteria during all types of fermentation accounting for 51% of 171 representative isolates taken from various stages of fermentation. Other major lactic acid bacteria found were Lactobacillus brevis, 16%, Leuconostoc mesenteroides, 15% and some cocci including Streptococcus spp. whose numbers decreased with fermentation time. The lactic acid bacteria were responsible for the souring of agbelima through the production of lactic acid. All L. plantarum, L. brevis and L. mesenteroides isolates examined demonstrated linamarase as well as other enzymatic activities but did not possess tissue degrading enzymes like cellulase, pectin esterase and polygalacturonase. The aroma profile of agbelima did not vary with the type of inoculum used and in all samples the build-up of aroma compounds were dominated by a non-identified low molecular weight alcohol, 1-propanol, isoamyl alcohol, ethyl acetate, 3-methyl-1-butanol and acetoin. Substantial reductions occurred in the levels of cyanogenic compounds present in cassava during fermentation into agbelima and detoxification was enhanced by the use of inoculum.

Comparative genomics of the lactic acid bacteria

Energy Technology Data Exchange (ETDEWEB)

Makarova, K.; Slesarev, A.; Wolf, Y.; Sorokin, A.; Mirkin, B.; Koonin, E.; Pavlov, A.; Pavlova, N.; Karamychev, V.; Polouchine, N.; Shakhova, V.; Grigoriev, I.; Lou, Y.; Rokhsar, D.; Lucas, S.; Huang, K.; Goodstein, D. M.; Hawkins, T.; Plengvidhya, V.; Welker, D.; Hughes, J.; Goh, Y.; Benson, A.; Baldwin, K.; Lee, J. -H.; Diaz-Muniz, I.; Dosti, B.; Smeianov, V; Wechter, W.; Barabote, R.; Lorca, G.; Altermann, E.; Barrangou, R.; Ganesan, B.; Xie, Y.; Rawsthorne, H.; Tamir, D.; Parker, C.; Breidt, F.; Broadbent, J.; Hutkins, R.; O' Sullivan, D.; Steele, J.; Unlu, G.; Saier, M.; Klaenhammer, T.; Richardson, P.; Kozyavkin, S.; Weimer, B.; Mills, D.

2006-06-01

Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats.

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.

Wetspun poly-L-(lactic acid)-borosilicate bioactive glass scaffolds for guided bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Fernandes, João S., E-mail: joao.fernandes@dep.uminho.pt [3B' s Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque de Ciência e Tecnologia, Zona Industrial da Gandra, 4805-017 Barco GMR (Portugal); ICVS/3B' s - PT Government Associate Laboratory, Braga/Guimarães (Portugal); Reis, Rui L. [3B' s Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque de Ciência e Tecnologia, Zona Industrial da Gandra, 4805-017 Barco GMR (Portugal); ICVS/3B' s - PT Government Associate Laboratory, Braga/Guimarães (Portugal); Pires, Ricardo A., E-mail: rpires@dep.uminho.pt [3B' s Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque de Ciência e Tecnologia, Zona Industrial da Gandra, 4805-017 Barco GMR (Portugal); ICVS/3B' s - PT Government Associate Laboratory, Braga/Guimarães (Portugal)

2017-02-01

We developed a porous poly-L-lactic acid (PLLA) scaffold compounded with borosilicate bioactive glasses (BBGs) endowing it with bioactive properties. Porous PLLA-BBG fibre mesh scaffolds were successfully prepared by the combination of wet spinning and fibre bonding techniques. Micro-computed tomography (μCT) confirmed that the PLLA-BBG scaffolds containing ≈ 25% of BBGs (w/w) exhibited randomly interconnected porous (58 to 62% of interconnectivity and 53 to 67% of porosity) with mean pore diameters higher that 100 μm. Bioactivity and degradation studies were performed by immersing the scaffolds in simulated body fluid (SBF) and ultrapure water, respectively. The PLLA-BBG scaffolds presented a faster degradation rate with a constant release of inorganic species, which are capable to produce calcium phosphate structures at the surface of the material after 7 days of immersion in SBF (Ca/P ratio of ~ 1.7). Cellular in vitro studies with human osteosarcoma cell line (Saos-2) and human adipose-derived stem cells (hASCs) showed that PLLA-BBGs are not cytotoxic to cells, while demonstrating their capacity to promote cell adhesion and proliferation. Overall, we showed that the proposed scaffolds present a tailored kinetics on the release of inorganic species and controlled biological response under conditions that mimic the bone physiological environment. - Highlights: • We prepared borosilicate glasses and their PLLA composites in the form of fibres. • These glasses imparted bioactivity and controlled degradability to the fibres. • The prepared fibres did not elicit cytotoxicity. • hASCs attached and proliferated in the surface and inner sections of the scaffolds. • The composites present appropriate properties to be used in bone tissue engineering.

Poly(lactic-co-glycolic acid) devices: Production and applications for sustained protein delivery.

Science.gov (United States)

Lee, Parker W; Pokorski, Jonathan K

2018-03-13

Injectable or implantable poly(lactic-co-glycolic acid) (PLGA) devices for the sustained delivery of proteins have been widely studied and utilized to overcome the necessity of repeated administrations for therapeutic proteins due to poor pharmacokinetic profiles of macromolecular therapies. These devices can come in the form of microparticles, implants, or patches depending on the disease state and route of administration. Furthermore, the release rate can be tuned from weeks to months by controlling the polymer composition, geometry of the device, or introducing additives during device fabrication. Slow-release devices have become a very powerful tool for modern medicine. Production of these devices has initially focused on emulsion-based methods, relying on phase separation to encapsulate proteins within polymeric microparticles. Process parameters and the effect of additives have been thoroughly researched to ensure protein stability during device manufacturing and to control the release profile. Continuous fluidic production methods have also been utilized to create protein-laden PLGA devices through spray drying and electrospray production. Thermal processing of PLGA with solid proteins is an emerging production method that allows for continuous, high-throughput manufacturing of PLGA/protein devices. Overall, polymeric materials for protein delivery remain an emerging field of research for the creation of single administration treatments for a wide variety of disease. This review describes, in detail, methods to make PLGA devices, comparing traditional emulsion-based methods to emerging methods to fabricate protein-laden devices. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Implantable Materials and Surgical Technologies > Nanomaterials and Implants Biology-Inspired Nanomaterials > Peptide-Based Structures. © 2018 Wiley Periodicals, Inc.

Degradability Enhancement of Poly(Lactic Acid) by Stearate-Zn3Al LDH Nanolayers

Science.gov (United States)

Eili, Mahboobeh; Shameli, Kamyar; Ibrahim, Nor Azowa; Yunus, Wan Md Zin Wan

2012-01-01

Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn3Al LDH. A solution casting method was used to prepare PLA/stearate-Zn3Al LDH nanocomposites. The anionic clay Zn3Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn3Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn3Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn3Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn3Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn3Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA. PMID:22942682

Wetspun poly-L-(lactic acid)-borosilicate bioactive glass scaffolds for guided bone regeneration

International Nuclear Information System (INIS)

Fernandes, João S.; Reis, Rui L.; Pires, Ricardo A.

2017-01-01

We developed a porous poly-L-lactic acid (PLLA) scaffold compounded with borosilicate bioactive glasses (BBGs) endowing it with bioactive properties. Porous PLLA-BBG fibre mesh scaffolds were successfully prepared by the combination of wet spinning and fibre bonding techniques. Micro-computed tomography (μCT) confirmed that the PLLA-BBG scaffolds containing ≈ 25% of BBGs (w/w) exhibited randomly interconnected porous (58 to 62% of interconnectivity and 53 to 67% of porosity) with mean pore diameters higher that 100 μm. Bioactivity and degradation studies were performed by immersing the scaffolds in simulated body fluid (SBF) and ultrapure water, respectively. The PLLA-BBG scaffolds presented a faster degradation rate with a constant release of inorganic species, which are capable to produce calcium phosphate structures at the surface of the material after 7 days of immersion in SBF (Ca/P ratio of ~ 1.7). Cellular in vitro studies with human osteosarcoma cell line (Saos-2) and human adipose-derived stem cells (hASCs) showed that PLLA-BBGs are not cytotoxic to cells, while demonstrating their capacity to promote cell adhesion and proliferation. Overall, we showed that the proposed scaffolds present a tailored kinetics on the release of inorganic species and controlled biological response under conditions that mimic the bone physiological environment. - Highlights: • We prepared borosilicate glasses and their PLLA composites in the form of fibres. • These glasses imparted bioactivity and controlled degradability to the fibres. • The prepared fibres did not elicit cytotoxicity. • hASCs attached and proliferated in the surface and inner sections of the scaffolds. • The composites present appropriate properties to be used in bone tissue engineering.

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

International Nuclear Information System (INIS)

Fonseca, Carmen; Ochoa, Almudena; Ulloa, Maria Teresa; Alvarez, Eduardo; Canales, Daniel; Zapata, Paula A.

2015-01-01

Poly(lactic acid) (PLA) composites with titanium oxide (TiO 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 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 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 2 composites with 8 wt.% TiO 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 2 killing 94% of the bacteria. The PLA/TiO 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 2 was added. • The elastic modulus increased ~ 54% compared to neat PLA. • The PLA/TiO 2 composites showed a reduction of Escherichia coli colonies of 94%. • The PLA/TiO 2 nanocomposites with 8 wt.% were also 99.99% effective against fungi

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

Directory of Open Access Journals (Sweden)

Young Il Yoon

2013-01-01

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

Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications

Energy Technology Data Exchange (ETDEWEB)

Abdal-hay, Abdalla, E-mail: abda_55@jbnu.ac.kr [Dept of Engineering Materials and Mechanical Design, Faculty of Engineering, South Valley of University, Qena 83523 (Egypt); Hussein, Kamal Hany [Stem Cell Institute and College of Veterinary Medicine, Kangwon National University, Chuncheon, Gangwon 200-701 (Korea, Republic of); Casettari, Luca [Department of Biomolecular Sciences, University of Urbino, Piazza Rinascimento, 6, Urbino, PU 61029 (Italy); Khalil, Khalil Abdelrazek [Dept. of Mechanical Engineering, College of Engineering, King Saud University, 800, Riyadh 11421 (Saudi Arabia); Dept. of Mechanical Engineering, Faculty of Energy Engineering, Aswan University, Aswan (Egypt); Hamdy, Abdel Salam [Dept. of Manufacturing and Industrial Engineering, College of Engineering and Computer Science, University of Texas Rio Grande Valley, 1201 West University Dr., Edinburg, TX 78541-2999 (United States)

2016-03-01

Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low (hydrophilicity) and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265 ± 222 nm, which is remarkably higher than its pristine counterpart (650 ± 180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11 ± 1.5°) compared to that of pristine PLA (119.7 ± 1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine. - Highlights: • Novel PVA-coated PLA nanofibers were prepared by a simple hydrothermal route. • This in situ treatment strategy for PLA fibers induced polymer chain conformation. • Bonding interaction

Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications

International Nuclear Information System (INIS)

Abdal-hay, Abdalla; Hussein, Kamal Hany; Casettari, Luca; Khalil, Khalil Abdelrazek; Hamdy, Abdel Salam

2016-01-01

Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low (hydrophilicity) and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265 ± 222 nm, which is remarkably higher than its pristine counterpart (650 ± 180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11 ± 1.5°) compared to that of pristine PLA (119.7 ± 1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine. - Highlights: • Novel PVA-coated PLA nanofibers were prepared by a simple hydrothermal route. • This in situ treatment strategy for PLA fibers induced polymer chain conformation. • Bonding interaction

Evaluation of poly(lactic-co-glycolic acid) and poly(DL-lactide-co-ε-caprolactone) electrospun fibers for the treatment of HSV-2 infection

Energy Technology Data Exchange (ETDEWEB)

Aniagyei, Stella E.; Sims, Lee B. [Department of Bioengineering, University of Louisville, Louisville, KY 40202 (United States); Malik, Danial A. [Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202 (United States); Tyo, Kevin M. [Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202 (United States); Center for Predictive Medicine, University of Louisville, Louisville, KY 40202 (United States); Curry, Keegan C. [Department of Bioengineering, University of Louisville, Louisville, KY 40202 (United States); Kim, Woihwan [Department of Medicine, University of Louisville, Louisville, KY 40202 (United States); Hodge, Daniel A. [Department of Bioengineering, University of Louisville, Louisville, KY 40202 (United States); Duan, Jinghua [Department of Bioengineering, University of Louisville, Louisville, KY 40202 (United States); Center for Predictive Medicine, University of Louisville, Louisville, KY 40202 (United States); Steinbach-Rankins, Jill M., E-mail: jill.steinbach@louisville.edu [Department of Bioengineering, University of Louisville, Louisville, KY 40202 (United States); Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202 (United States); Department of Microbiology and Immunology, University of Louisville, Louisville, KY 40202 (United States); Center for Predictive Medicine, University of Louisville, Louisville, KY 40202 (United States)

2017-03-01

More diverse multipurpose prevention technologies are urgently needed to provide localized, topical pre-exposure prophylaxis against sexually transmitted infections (STIs). In this work, we established the foundation for a multipurpose platform, in the form of polymeric electrospun fibers (EFs), to physicochemically treat herpes simplex virus 2 (HSV-2) infection. To initiate this study, we fabricated different formulations of poly(lactic-co-glycolic acid) (PLGA) and poly(DL-lactide-co-ε-caprolactone) (PLCL) EFs that encapsulate Acyclovir (ACV), to treat HSV-2 infection in vitro. Our goals were to assess the release and efficacy differences provided by these two different biodegradable polymers, and to determine how differing concentrations of ACV affected fiber efficacy against HSV-2 infection and the safety of each platform in vitro. Each formulation of PLGA and PLCL EFs exhibited high encapsulation efficiency of ACV, sustained-delivery of ACV through one month, and in vitro biocompatibility at the highest doses of EFs tested. Additionally, all EF formulations provided complete and efficacious protection against HSV-2 infection in vitro, regardless of the timeframe of collected fiber eluates tested. This work demonstrates the potential for PLGA and PLCL EFs as delivery platforms against HSV-2, and indicates that these delivery vehicles may be expanded upon to provide protection against other sexually transmitted infections. - Highlights: • PLGA and PLCL EFs exhibit sustained-delivery of ACV through one month. • EFs exhibit high ACV encapsulation efficiency and in vitro biocompatibility. • EFs serve as both physical and chemical barriers to HSV-2 infection. • Potent in vitro efficacy is provided against HSV-2 infection for all formulations. • HSV-2 protection is independent of administration times within one month.

Evaluation of poly(lactic-co-glycolic acid) and poly(DL-lactide-co-ε-caprolactone) electrospun fibers for the treatment of HSV-2 infection

International Nuclear Information System (INIS)

Aniagyei, Stella E.; Sims, Lee B.; Malik, Danial A.; Tyo, Kevin M.; Curry, Keegan C.; Kim, Woihwan; Hodge, Daniel A.; Duan, Jinghua; Steinbach-Rankins, Jill M.

2017-01-01

More diverse multipurpose prevention technologies are urgently needed to provide localized, topical pre-exposure prophylaxis against sexually transmitted infections (STIs). In this work, we established the foundation for a multipurpose platform, in the form of polymeric electrospun fibers (EFs), to physicochemically treat herpes simplex virus 2 (HSV-2) infection. To initiate this study, we fabricated different formulations of poly(lactic-co-glycolic acid) (PLGA) and poly(DL-lactide-co-ε-caprolactone) (PLCL) EFs that encapsulate Acyclovir (ACV), to treat HSV-2 infection in vitro. Our goals were to assess the release and efficacy differences provided by these two different biodegradable polymers, and to determine how differing concentrations of ACV affected fiber efficacy against HSV-2 infection and the safety of each platform in vitro. Each formulation of PLGA and PLCL EFs exhibited high encapsulation efficiency of ACV, sustained-delivery of ACV through one month, and in vitro biocompatibility at the highest doses of EFs tested. Additionally, all EF formulations provided complete and efficacious protection against HSV-2 infection in vitro, regardless of the timeframe of collected fiber eluates tested. This work demonstrates the potential for PLGA and PLCL EFs as delivery platforms against HSV-2, and indicates that these delivery vehicles may be expanded upon to provide protection against other sexually transmitted infections. - Highlights: • PLGA and PLCL EFs exhibit sustained-delivery of ACV through one month. • EFs exhibit high ACV encapsulation efficiency and in vitro biocompatibility. • EFs serve as both physical and chemical barriers to HSV-2 infection. • Potent in vitro efficacy is provided against HSV-2 infection for all formulations. • HSV-2 protection is independent of administration times within one month.

The impact of lactic acid bacteria on sourdough fermentation

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Savić Dragiša S.

2005-01-01

Full Text Available The baking of sourdough breads represents one of the oldest biotechnological processes. Despite traditionality, sourdough bread has great potential because of its benefits. Sourdough is a mixture of flour and water that is dominated by a complex microflora composed of yeasts and lactic acid bacteria that are crucial in the preparation of bread dough. Lactic acid bacteria cause acidification by producing lactic acid that increases the shelf life of bread by preventing the growth of undesirable microorganisms and affects the nutritional value of bread by increasing the availability of minerals. In addition to these advantages, the use of sourdough fermentation also improves dough machinability, breadcrumb structure and the characteristic flavour of bread. Lactic acid bacteria in sourdough fermentation are well known representing both homofermentative and heterofermentative bacteria. They may originate from selected natural contaminants in the flour or from a starter culture containing one or more known species of lactic acid bacteria. Sourdough can be cultivated in bakeries or obtained from commercial suppliers. However, many bakeries in Europe still use spontaneously fermented sourdoughs, which have been kept metabolically active for decades by the addition of flour and water at regular intervals. The impact of lactic acid bacteria on sourdough fermentation and their influence on dough and bread quality was discussed on the basis of research and literature data.

Exploitation of vegetables and fruits through lactic acid fermentation.

Science.gov (United States)

Di Cagno, Raffaella; Coda, Rossana; De Angelis, Maria; Gobbetti, Marco

2013-02-01

Lactic acid fermentation represents the easiest and the most suitable way for increasing the daily consumption of fresh-like vegetables and fruits. Literature data are accumulating, and this review aims at describing the main features of the lactic acid bacteria to be used for fermentation. Lactic acid bacteria are a small part of the autochthonous microbiota of vegetables and fruits. The diversity of the microbiota markedly depends on the intrinsic and extrinsic parameters of the plant matrix. Notwithstanding the reliable value of the spontaneous fermentation to stabilize and preserve raw vegetables and fruits, a number of factors are in favour of using selected starters. Two main options may be pursued for the controlled lactic acid fermentation of vegetables and fruits: the use of commercial/allochthonous and the use of autochthonous starters. Several evidences were described in favour of the use of selected autochthonous starters, which are tailored for the specific plant matrix. Pro-technological, sensory and nutritional criteria for selecting starters were reported as well as several functional properties, which were recently ascribed to autochthonous lactic acid bacteria. The main features of the protocols used for the manufacture of traditional, emerging and innovative fermented vegetables and fruits were reviewed. Tailored lactic acid bacteria starters completely exploit the potential of vegetables and fruits, which enhances the hygiene, sensory, nutritional and shelf life properties. Copyright © 2012 Elsevier Ltd. All rights reserved.

Novel multi-biotin grafted poly(lactic acid) and its self-assembling nanoparticles capable of binding to streptavidin

Science.gov (United States)

Yan, Hao; Jiang, Weimin; Zhang, Yinxing; Liu, Ying; Wang, Bin; Yang, Li; Deng, Lihong; Singh, Gurinder K; Pan, Jun

2012-01-01

Targeted drug delivery requires novel biodegradable, specific binding systems with longer circulation time. The aim of this study was to prepare biotinylated poly(lactic acid) (PLA) nanoparticles (NPs) which can meet regular requirements as well conjugate more biotins in the polymer to provide better binding with streptavidin. A biotin-graft-PLA was synthesized based on previously published biodegradable poly(ethylene glycol) (PEG)-graft-PLA, with one polymer molecule containing three PEG molecules. Newly synthesized biotin-graft-PLA had three biotins per polymer molecule, higher than the previous biotinylated PLA (≤1 biotin per polymer molecule). A PEG with a much lower molecular weight (MW ~1900) than the previous biotinylated PLA (PEG MW ≥ 3800), and thus more biocompatible, was used which supplied good nonspecific protein-resistant property compatible to PEG-graft-PLA, suggesting its possible longer stay in the bloodstream. Biotin-graft-PLA specifically bound to streptavidin and self-assembled into NPs, during which naproxen, a model small molecule (MW 230 Da) and hydrophobic drug, was encapsulated (encapsulation efficiency 51.88%). The naproxen-loaded NPs with particle size and zeta potential of 175 nm and −27.35 mV realized controlled release within 170 hours, comparable to previous studies. The biotin-graft-PLA NPs adhered approximately two-fold more on streptavidin film and on biotin film via a streptavidin arm both in static and dynamic conditions compared with PEG-graft-PLA NPs, the proven nonspecific protein-resistant NPs. The specific binding of biotin-graft-PLA NPs with streptavidin and with biotin using streptavidin arm, as well as its entrapment and controlled release for naproxen, suggest potential applications in targeted drug delivery. PMID:22334778

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

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

2015-11-01

Lysine-doped polypyrrole (PPy)/regenerated spider silk protein (RSSP)/poly(l-lactic) acid (PLLA)/nerve growth factor (NGF) (L-PRPN) composite scaffold was fabricated by co-axial electrospraying and electrospinning. This L-PRPN composite scaffold had a structure of microfibers with a core-shell structure as the stems and nanofibers as branches. Assessment in vitro demonstrated that the L-PRPN composite micro/nano-fibrous scaffold could maintain integrated structure for at least 4months and the pH value of PBS at about 7.28. It had good biocompatibility and cell adhesion and relatively stable conductivity. PC 12 cells cultured on this scaffold, anisotropic cell-neurite-cell-neurite or neurite-neurite sheets were formed after being cultured for 6days. Evaluations in vivo also showed that L-PRPN composite fibrous conduit was effective at bridging 2.0cm sciatic nerve gap in adult rat within 10months. This conduit and electrical stimulation (ES) through it promoted Schwann cell migration and axonal regrowth. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of electrospun poly(lactic acid and nanohydroxyapatite nanofibers’ diameter on proliferation and differentiation of mesenchymal stem cells

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Amir Doustgani

2016-10-01

Full Text Available Objective(s: Electrospun nanofibrous mats of poly(lactic acid (PLA and nanohydroxyapatite (nano-HA were prepared and proliferation and differentiation of mesenchymal stem cells on the prepared nanofibers were investigated in this study. Materials and Methods: PLA/nano-HA nanofibers were prepared by electrospinning. The effects of process parameters, such as nano-HA concentration, distance, applied voltage, and flow rate on the mean diameter of electrospun nanofibers were investigated. Scanning electron microscopy (SEM was used to determine the mean fiber diameter of produced nanofibers. Mechanical propertes of nanofibrous mats were evaluated using a universal testing machine. Response surface methodology was used to model the fiber diameter of electrospun PLA/nano-HA nanofibers. Results: The average fiber diameter for optimized nanofibers was 125 ± 11 nm. MTT and ALP results showed that optimization of fiber diameter increased the osteogenic differentiation of stem cells. Conclusion: It could be concluded that optimization of fiber diameter has beneficial effect on cell proliferation and differentiation. Optimized nanofibers of PLA/nano-HA could be good candidates for bone tissue engineering.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

9th International Symposium on Lactic Acid Bacteria

NARCIS (Netherlands)

Kuipers, Oscar P.; Poolman, Berend; Hugenholtz, Jeroen

What’s new in the field of lactic acid bacteria? The 9th International Symposium on Lactic Acid Bacteria (LAB9) will take place 31 August to 4 September 2008 in Egmond aan Zee, The Netherlands. Traditionally, the triannual LAB symposium focuses on the themes of genetics, physiology, and applications

Bacteriocins and lactic acid bacteria - a minireview | Savadogo ...

African Journals Online (AJOL)

Fermentation of various foods by lactic acid bacteria (LAB) is one of the oldest forms of biopreservation practised by mankind. Bacterial antagonism has been recognized for over a century but in recent years this phenomenon has received more scientific attention, particulary in the use of various strains of lactic acid bacteria.

Potential Use of Gelidium amansii Acid Hydrolysate for Lactic Acid Production by Lactobacillus rhamnosus

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Sung-Soo Jang

2013-01-01

Full Text Available Galactose and glucose are the main monosaccharides produced from the saccharification of Gelidium amansii. They were hydrolysed with 3 % (by volume H2SO4 at 140 °C for 5 min and obtained at concentrations of 19.60 and 10.21 g/L, respectively. G. amansii hydrolysate (5 %, by mass per volume was used as a substrate for L(+-lactic acid production by Lactobacillus rhamnosus. The maximum lactic acid yield (YP/S was 42.03 % with optical purity of 84.54 %. Lactic acid produced from G. amansii hydrolysate can be applicable, among others, for the production of lactic acid esters, like ethyl or methyl lactate, and disinfectant in seaweed cultivation.

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.

[Biocompatibility of poly-L-lactic acid/Bioglass-guided bone regeneration membranes processed with oxygen plasma].

Science.gov (United States)

Fang, Wei; Zeng, Shu-Guang; Gao, Wen-Feng

2015-04-01

To prepare and characterize a nano-scale fibrous hydrophilic poly-L-lactic acid/ Bioglass (PLLA/BG) composite membrane and evaluate its biocompatibility as a composite membrane for guiding bone regeneration (GBR). PLLA/BG-guided bone regeneration membrane was treated by oxygen plasma to improved its hydrophilicity. The growth of MG-63 osteoblasts on the membrane was observed using Hoechst fluorescence staining, and the biocompatibility of the membrane was evaluated by calculating the cells adhesion rate and proliferation rate. Osteogenesis of MG-63 cells was assessed by detecting alkaline phosphatase (ALP), and the formation of calcified nodules and cell morphology changes were observed using scanning electron microscope (SEM). The cell adhesion rates of PLLA/BG-guided bone regeneration membrane treated with oxygen plasma were (30.570±0.96)%, (47.27±0.78)%, and (66.78±0.69)% at 1, 3, and 6 h, respectively, significantly higher than those on PLLA membrane and untreated PLLA/BG membrane (Pmembranes increased with time, but highest on oxygen plasma-treated PLLA/BG membrane (Pplasma treatment of the PLLA/BG membrane promoted cell adhesion. The membranes with Bioglass promoted the matrix secretion of the osteoblasts. Under SEM, the formation of calcified nodules and spindle-shaped cell morphology were observed on oxygen plasma-treated PLLA/BG membrane. Oxygen plasma-treated PLLA/BG composite membrane has good biocompatibility and can promote adhesion, proliferation and osteogenesis of the osteoblasts.

Heme and menaquinone induced electron transport in lactic acid bacteria

OpenAIRE

Brooijmans, Rob; Smit, Bart; Santos, Filipe; van Riel, Jan; de Vos, Willem M; Hugenholtz, Jeroen

2009-01-01

Abstract Background For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait. Results Heme- (and menaquinone) stimulated aerobic growth was observed for several species and genera of lactic acid bacteria. These include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacill...

Biocompatible cephalosporin-hydroxyapatite-poly(lactic-co-glycolic acid)-coatings fabricated by MAPLE technique for the prevention of bone implant associated infections

Science.gov (United States)

Rădulescu, Dragoş; Grumezescu, Valentina; Andronescu, Ecaterina; Holban, Alina Maria; Grumezescu, Alexandru Mihai; Socol, Gabriel; Oprea, Alexandra Elena; Rădulescu, Marius; Surdu, Adrian; Trusca, Roxana; Rădulescu, Radu; Chifiriuc, Mariana Carmen; Stan, Miruna S.; Constanda, Sabrina; Dinischiotu, Anca

2016-06-01

In this study we aimed to obtain functionalized thin films based on hydroxyapatite/poly(lactic-co-glycolic acid) (HAp/PLGA) containing ceftriaxone/cefuroxime antibiotics (ATBs) deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. The prepared thin films were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-Ray diffraction (XRD), selected area electron diffraction (SAED), and infra red (IR) analysis. HAp/PLGA/ATBs thin films sustained the growth of human osteoblasts, proving their good biocompatibility. The microscopic evaluation and the culture-based quantitative assay of the E. coli biofilm development showed that the thin films inhibited the initial step of microbial attachment as well as the subsequent colonization and biofilm development on the respective surfaces. This study demonstrates that MAPLE technique could represent an appealing technique for the fabrication of antibiotics-containing polymeric implant coatings. The bioevaluation results recommend this type of surfaces for the prevention of bone implant microbial contamination and for the enhanced stimulation of the implant osseointegration process.

Mechanochemical Ring-Opening Polymerization of Lactide: Liquid-Assisted Grinding for the Green Synthesis of Poly(lactic acid) with High Molecular Weight.

Science.gov (United States)

Ohn, Nuri; Shin, Jihoon; Kim, Sung Sik; Kim, Jeung Gon

2017-09-22

Mechanochemical polymerization of lactide is carried out by using ball milling. Mechanical energy from collisions between the balls and the vessel efficiently promotes an organic-base-mediated metal- and solvent-free solid-state polymerization. Investigation of the parameters of the ball-milling synthesis revealed that the degree of lactide ring-opening polymerization could be modulated by the ball-milling time, vibration frequency, mass of the ball media, and liquid-assisted grinding. Liquid-assisted grinding was found to be an especially important factor for achieving a high degree of mechanochemical polymerization. Although polymer-chain scission from the strong collision energy prevented mechanical-force-driven high-molecular-weight polymer synthesis, the addition of only a small amount of liquid enabled sufficient energy dissipation and poly(lactic acid) was thereby obtained with a molecular weight of over 1×10 5  g mol -1 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphological and mechanical properties of thermoplastic starch (TPS) and its blend with poly(lactic acid)(PLA) using cassava bagasse and starch

International Nuclear Information System (INIS)

Teixeira, Eliangela de M.; Correa, Ana C.; Campos, Adriana de; Marconcini, Jose M.; Mattoso, Luiz H.C.; Curvelo, Antonio A.S.

2011-01-01

This study aims the use of an agro waste coming from the industrialization of cassava starch, known as cassava bagasse (BG). This material contains residual starch and cellulose fibers which can be used to obtain thermoplastic starch (TPS) and /or blends reinforced with fibers. In this context, it was prepared a thermoplastic starch with BG (TPSBG) and evaluated the incorporation of 20wt% of it into the biodegradable polymer poly (lactic acid) (PLA), resulting in a blend PLA/TPSBG20. The materials were investigated through morphology (scanning electron microscopy with field emission gun (FEG), x-ray diffraction (XRD), and mechanical behavior (tensile test). Their properties were compared to the blend PLA/TPSI20 in which TPSI is obtained from commercial cassava starch. The results showed that the use of bagasse generates homogenous materials with higher mechanical strength if compared to TPS obtained from commercial cassava starch. The fiber in this residue acted as reinforcement for TPS and PLA/TPS systems. (author)