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

OpenAIRE

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

2014-01-01

A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were inc...

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

Directory of Open Access Journals (Sweden)

Wang X

2015-01-01

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

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

Impacts of aeration management and polylactic acid addition on dissolved organic matter characteristics in intensified aquaponic systems.

Science.gov (United States)

Wu, Haiming; Zou, Yina; Lv, Jialong; Hu, Zhen

2018-08-01

Aquaponics as a potential alternative for conventional aquaculture industry has increasingly attracted worldwide attention in recent years. However, the sustainable application of aquaponics is facing a growing challenge. In particular, there is a pressing need to better understand and control the accumulation of dissolved organic matter (DOM) in aquaponics with the aim of optimizing nitrogen utilization efficiency. This study was aiming for assessing the characteristics of DOM in the culture water and the relationship with the nitrogen transformations in different intensified aquaponic systems with hydroponic aeration supplement and polylactic acid (PLA) addition. Two enhancing attempts altered the quantity of DOM in aquaponic systems significantly with a varying DOM content of 21.98-45.65 mg/L. The DOM could be represented by four identified fluorescence components including three humic -like materials (83-86%) and one tryptophan-like substance (14-17%). The fluorescence intensities of humic acid-like components were decreased significantly after the application of intensifying strategies, which indicating that two enhancing attempts possibly affected humic acid-like fluorescence. Variation of optical indices also suggested the reductions of water DOM which could be impacted by the enhancing nitrogen treatment processes. These findings will benefit the potential applications and sustainable operation of these strategies in aquaponics. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

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)

In vitro and in vivo evaluation of polylactic acid-based composite with tricalcium phosphate microsphere for enhanced biodegradability and osseointegration.

Science.gov (United States)

Shin, Da Yong; Kang, Min-Ho; Kang, In-Gu; Kim, Hyoun-Ee; Jeong, Seol-Ha

2018-05-01

A biodegradable polylactic acid composite containing tricalcium phosphate microsphere was fabricated. The composite exhibited enhanced biocompatibility and a well-interconnected porous structure that enabled tissue ingrowth after degradation. The tricalcium phosphate microspheres had an average size of 106 ± 43 μm and were incorporated into the polylactic acid matrix using a high-shear mixer. The resulting bioactivity and hydrophilicity were enhanced to levels comparable to those of a polylactic acid composite containing tricalcium phosphate powder, which is a well-known material used in the medical field. An accelerated 30-day degradation test in HCl revealed successful generation of an open porous structure with ∼98% interconnectivity in the polylactic acid-tricalcium phosphate microsphere composite, demonstrating the potential of this material to induce enhanced osseointegration in the later stage of bone regeneration. The early stage osseointegration was also evaluated by implanting the composite in vivo using a rabbit femoral defect model. After 16 weeks of implantation, the bone-to-implant contact ratio of the polylactic acid-tricalcium phosphate microsphere composite was enhanced owing to tissue ingrowth through the generated pores near the surface.

New Polylactic Acid Composites Reinforced with Artichoke Fibers

OpenAIRE

Botta, Luigi; Fiore, Vincenzo; Scalici, Tommaso; Valenza, Antonino;  , Roberto

2015-01-01

In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanica...

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

Science.gov (United States)

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

2015-08-19

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

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

KAUST Repository

Bugatti, Valeria; Livi, Sebastien; Hayrapetyan, Suren; Wang, Yue; Estevez, Luis; Vittoria, Vittoria; Giannelis, Emmanuel P.

2013-01-01

A simple and scalable deposition process was developed to prepare polylactic acid (PLA) coatings with enhanced water barrier properties for food packaging applications. This method based on electrostatic interactions between the positively charged

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

Science.gov (United States)

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

2016-01-01

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

Characterization and ageing study of poly(lactic acid) films plasticized with oligomeric lactic acid

OpenAIRE

Burgos, Nuria; Martino, Verónica P.; Jiménez, Alfonso

2013-01-01

Poly(lactic acid) (PLA) was melt-blended with a bio-based oligomeric lactic acid (OLA) plasticizer at different concentrations between 15 wt% and 25 wt% in order to enhance PLA ductility and to get a fully biodegradable material with potential application in films manufacturing. OLA was an efficient plasticizer for PLA, as it caused a significant decrease on glass transition temperature (Tg) while improving considerably ductile properties. Only one Tg value was observed in all cases and no ap...

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...

Margination of Fluorescent Polylactic Acid–Polyaspartamide based Nanoparticles in Microcapillaries In Vitro: the Effect of Hematocrit and Pressure

Directory of Open Access Journals (Sweden)

Emanuela Fabiola Craparo

2017-10-01

Full Text Available The last decade has seen the emergence of vascular-targeted drug delivery systems as a promising approach for the treatment of many diseases, such as cardiovascular diseases and cancer. In this field, one of the major challenges is carrier margination propensity (i.e., particle migration from blood flow to vessel walls; indeed, binding of these particles to targeted cells and tissues is only possible if there is direct carrier–wall interaction. Here, a microfluidic system mimicking the hydrodynamic conditions of human microcirculation in vitro is used to investigate the effect of red blood cells (RBCs on a carrier margination in relation to RBC concentration (hematocrit and pressure drop. As model drug carriers, fluorescent polymeric nanoparticles (FNPs were chosen, which were obtained by using as starting material a pegylated polylactic acid–polyaspartamide copolymer. The latter was synthesized by derivatization of α,β-poly(N-2-hydroxyethyl-d,l-aspartamide (PHEA with Rhodamine (RhB, polylactic acid (PLA and then poly(ethyleneglycol (PEG chains. It was found that the carrier concentration near the wall increases with increasing pressure drop, independently of RBC concentration, and that the tendency for FNP margination decreases with increasing hematocrit. This work highlights the importance of taking into account RBC–drug carrier interactions and physiological conditions in microcirculation when planning a drug delivery strategy based on systemically administered carriers.

Biodegradability of injection molded bioplastics containing polylactic acid and poultry feather fiber

Science.gov (United States)

Biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide (CO2) produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was...

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...

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

Directory of Open Access Journals (Sweden)

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.

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

Czech Academy of Sciences Publication Activity Database

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

2007-01-01

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

Melt-spun polylactic acid fibers: effect of cellulose nanowhiskers on processing and properties

CSIR Research Space (South Africa)

John, MJ

2012-04-01

Full Text Available Bio-based continuous fibers were processed from polylactic acid (PLA) and cellulose nanowhiskers (CNWs) by melt spinning. Melt compounding of master batches of PLA with 10 wt % CNWs and pure PLA was carried out using a twin-screw extruder in which...

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

International Nuclear Information System (INIS)

Kim, Il-Young; Jung, Ui-Won; Kim, Chang-Sung; Lee, Yong-Keun; Cho, Kyoo-Sung; Chai, Jung-Kiu; Kim, Chong-Kwan; Choi, Seong-Ho

2007-01-01

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

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...

Purposeful exposure of a polylactic acid barrier to achieve socket preservation for placement of dental implants: case series report.

Science.gov (United States)

Rosen, Paul S; Rosen, Adam D

2013-01-01

This retrospective case series reports on the use of a polylactic acid barrier that was left exposed in the process of socket preparation for the placement of dental implants. A retrospective chart review found 43 patients with 48 extraction sockets that were treated in this manner. Teeth were removed and the sockets were thoroughly debrided, with 40 of them receiving a bone replacement graft covered by the polylactic acid barrier and the additional 8 receiving the membrane alone. Suturing left the barrier exposed, and the sites were re-entered on average at 23 weeks for the placement of a dental implant. All sites were able to receive a dental implant, demonstrating the ability to leave a polylactic acid barrier exposed and achieve successful guided bone regeneration (GBR) results. This ultimately helped avoid some of the negative sequelae of trying to achieve primary closure of the flaps at the time of tooth extraction.

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)

Chemical and Sensory Evaluation of Silicone and Polylactic Acid-Based Remedial Treatments for Elevated Methoxypyrazine Levels in Wine

Directory of Open Access Journals (Sweden)

Andreea Botezatu

2016-09-01

Full Text Available Alkylmethoxypyrazines (MPs are a class of compounds that can elicit undesirable aroma and flavor characteristics in wine, and resist remediation using traditional wine making approaches. MPs are grape-derived constituents as well as contaminants from Coccinellidae beetles present during wine processing; the latter eliciting an off-flavor referred to as ‘ladybug taint’. In this study we investigated the capacity of two plastic polymers—one silicone-based, the other polylactic acid-based—applied with varying surface areas to reduce concentrations of isopropylmethoxypyrazine (IPMP, sec-butylmethoxypyrazine (SBMP and isobutylmethoxypyrazine (IBMP in a Merlot wine using multi-dimensional gas chromatography coupled with mass spectrometry and headspace solid phase microextraction (SPME-MDGCMS. The impact of treatments on the sensory characteristics of the wine (descriptive analysis and volatile aroma compounds (VOCs (SPME-MDGCMS was also investigated. Results showed substantial reductions for all of the target odorants: up to 38%, 44% and 39% for IPMP, SBMP and IBMP, respectively, for the silicone polymer, and up to 75%, 78% and 77% for IPMP, SBMP and IBMP, respectively, for the polylactic acid polymer. These polymers had no or minimal effect on VOCs at applications of 200 cm2/L for silicone or for all polylactic acid treatments. Sensory impacts were less clear, but generally showed minimal effect from the treatments. Taken overall, the data confirm the utility of both polylactic acid and silicone polymers in reducing elevated levels of grape-derived MPs, as well as potentially improving wine contaminated by ladybug taint.

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

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....

Advanced composite materials based on polyhydroxybutyrate and polylactic acid

Science.gov (United States)

Tubaeva, P. M.; Olkhov, A. A.; Podzorova, M. V.; Popov, A. A.

2017-12-01

In this paper, we consider the main characteristics of polyhydroxybutyrate (PHB) and polylactic acid (PLA) as well as the prospects and possibility of the medical use of PHB-PLA compositions as these polymers are most relevant to such application. The study establishes the main thermophysical parameters of PHB and PLA. It is found that PHB and PLA are hydrophobic enough. The study by the electron paramagnetic resonance method reveals a small amount of the radical infiltrated in PLA and PHB, which indicates the chain rigidity of both polymeric structures. Mechanical properties of PLA and PHB are characterized by high strength and low elasticity.

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.

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.

The effect of different clays on the structure, morphology and degradation behavior of poly(lactic acid)

CSIR Research Space (South Africa)

Neppalli, R

2014-01-01

Full Text Available In this work, polylactic acid (PLA)-based nanocomposites filled with different kinds of clay were prepared and their structure, morphology and degradation behavior were compared. A similar degree of dispersion was achieved in the case of cationic...

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

Science.gov (United States)

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

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...

Processing and Characterization of Cellulose Nanocrystals/Polylactic Acid Nanocomposite Films

Directory of Open Access Journals (Sweden)

Erin M. Sullivan

2015-12-01

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

Studies on Synthesis of Electrochemically Exfoliated Functionalized Graphene and Polylactic Acid/Ferric Phytate Functionalized Graphene Nanocomposites as New Fire Hazard Suppression Materials.

Science.gov (United States)

Feng, Xiaming; Wang, Xin; Cai, Wei; Qiu, Shuilai; Hu, Yuan; Liew, Kim Meow

2016-09-28

Practical application of functionalized graphene in polymeric nanocomposites is hampered by the lack of cost-effective and eco-friendly methods for its production. Here, we reported a facile and green electrochemical approach for preparing ferric phytate functionalized graphene (f-GNS) by simultaneously utilizing biobased phytic acid as electrolyte and modifier for the first time. Due to the presence of phytic acid, electrochemical exfoliation leads to low oxidized graphene sheets (a C/O ratio of 14.8) that are tens of micrometers large. Successful functionalization of graphene was confirmed by the appearance of phosphorus and iron peaks in the X-ray photoelectron spectrum. Further, high-performance polylactic acid/f-GNS nanocomposites are readily fabricated by a convenient masterbatch strategy. Notably, inclusion of well-dispersed f-GNS resulted in dramatic suppression on fire hazards of polylactic acid in terms of reduced peak heat-release rate (decreased by 40%), low CO yield, and formation of a high graphitized protective char layer. Moreover, obviously improvements in crystallization rate and thermal conductivities of polylactic acid nanocomposites were observed, highlighting its promising potential in practical application. This novel strategy toward the simultaneous exfoliation and functionalization for graphene demonstrates a simple yet very effective approach for fabricating graphene-based flame retardants.

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...

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

International Nuclear Information System (INIS)

Parker, N G; Povey, M J W; Mather, M L; Morgan, S P

2010-01-01

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

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

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.

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...

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...

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

Science.gov (United States)

Kang, Shuhui

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

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...

Biopolymer blends based on polylactic acid and polyhydroxy butyrate-co-valerate: effect of clay on mechanical and thermal properties

CSIR Research Space (South Africa)

John, MJ

2015-11-01

Full Text Available Biodegradable polymer blends consisting of polylactic acid (PLA) and polyhydroxy butyrate-co-valerate (PHBV) have been prepared by melt mixing in a twin screw extruder and followed by injection molding technique. Cereplast PLA containing starch...

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.

Terahertz absorption in graphite nanoplatelets/polylactic acid composites

Science.gov (United States)

Bychanok, D.; Angelova, P.; Paddubskaya, A.; Meisak, D.; Shashkova, L.; Demidenko, M.; Plyushch, A.; Ivanov, E.; Krastev, R.; Kotsilkova, R.; Ogrin, F. Y.; Kuzhir, P.

2018-04-01

The electromagnetic properties of composite materials based on poly(lactic) acid (PLA) filled with graphite nanoplatelets (GNP) were investigated in the microwave (26–37 GHz) and terahertz (0.2–1 THz) frequency ranges. The maximum of the imaginary part of the dielectric permittivity was observed close to 0.6 THz for composites with 1.5 and 3 wt.% of GNP. The experimental data of complex dielectric permittivity of GNP/PLA composites was modelled using the Maxwell-Garnett theory. The effects of fine dispersion, agglomeration, and percolation in GNP-based composites on its electromagnetic constitutive parameters, presence, and position of THz absorption peak are discussed on the basis of the modeling results and experimental data. The unique combination of conductive and geometrical parameters of GNP embedded into the PLA matrix below the percolation threshold allow us to obtain the THz-absorptive material, which may be effectively used as a 3D-printing filament.

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.

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.

A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning

International Nuclear Information System (INIS)

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

2012-01-01

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

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

A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning

Science.gov (United States)

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

2012-06-01

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

Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and Structure

OpenAIRE

Michael Arthur Cuiffo; Jeffrey Snyder; Alicia M. Elliott; Nicholas Romero; Sandhiya Kannan; Gary P. Halada

2017-01-01

Polylactic acid (PLA) is an organic polymer commonly used in fused deposition (FDM) printing and biomedical scaffolding that is biocompatible and immunologically inert. However, variations in source material quality and chemistry make it necessary to characterize the filament and determine potential changes in chemistry occurring as a result of the FDM process. We used several spectroscopic techniques, including laser confocal microscopy, Fourier transform infrared (FTIR) spectroscopy and pho...

Thermal degradation kinetics of polylactic acid/acid fabricated cellulose nanocrystal based bionanocomposites.

Science.gov (United States)

Monika; Dhar, Prodyut; Katiyar, Vimal

2017-11-01

Cellulose nanocrystals (CNC) are fabricated from filter paper (as cellulosic source) by acid hydrolysis using different acids such as sulphuric (H 2 SO 4 ), phosphoric (H 3 PO 4 ), hydrochloric (HCl) and nitric (HNO 3 ) acid. The resulting acid derived CNC are melt mixed with Polylactic acid (PLA) using extruder at 180°C. Thermogravimetric (TGA) result shows that increase in 10% and 50% weight loss (T 10 , T 50 ) temperature for PLA-CNC film fabricated with HNO 3 , H 3 PO 4 and HCl derived CNC have improved thermal stability in comparison to H 2 SO 4 -CNC. Nonisothermal kinetic studies are carried out with modified-Coats-Redfern (C-R), Ozawa-Flynn-Wall (OFW) and Kissinger method to predict the kinetic and thermodynamic parameters. Subsequently prediction of these parameter leads to the proposal of thermal induced degradation mechanism of nanocomposites using Criado method. The distribution of E a calculated from OFW model are (PLA-H 3 PO 4 -CNC: 125-139 kJmol -1 ), (PLA-HNO 3 -CNC: 126-145 kJmol -1 ), (PLA-H 2 SO 4 -CNC: 102-123 kJmol -1 ) and (PLA-HCl-CNC: 140-182 kJmol -1 ). This difference among E a for the decomposition of PLA-CNC bionanocomposite is probably due to various acids used in this study. The E a calculated by these two methods are found in consonance with that observed from Kissinger method. Further, hyphenated TG-Fourier transform infrared spectroscopy (FTIR) result shows that gaseous products such as CO 2 , CO, lactide, aldehydes and other compounds are given off during the thermal degradation of PLA-CNC nanocomposite. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Surface modification of polylactic acid films by atmospheric pressure plasma treatment

Science.gov (United States)

Kudryavtseva, V. L.; Zhuravlev, M. V.; Tverdokhlebov, S. I.

2017-09-01

A new approach for the modification of polylactic acid (PLA) materials using atmospheric pressure plasma (APP) is described. PLA films plasma exposure time was 20, 60, 120 s. The surface morphology and wettability of the obtained PLA films were investigated by atomic force microscopy (AFM) and the sitting drop method. The atmospheric pressure plasma increased the roughness and surface energy of PLA film. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. It was shown that it is possible to obtain PLA films with various surface relief and tunable wettability. Additionally, we demonstrated that the use of cold atmospheric pressure plasma for surface activation allows for the immobilization of bioactive compounds like hyaluronic acid (HA) on the surface of obtained films. It was shown that composite PLA-HA films have an increased long-term hydrophilicity of the films surface.

The effect of thyme oil low-density polyethylene impregnated pellets in polylactic acid sachets on storage quality of ready-to-eat avocado

CSIR Research Space (South Africa)

Bill, M

2018-01-01

Full Text Available -LDPE-P) in polylactic acid (PLA) sachets was investigated for the control of anthracnose and retention of dietary phytochemicals, fatty acid composition, D-mannoheptulose sugar and fruit quality in ready-to-eat avocado fruit. The 10% TO-LDPE-P significantly reduced...

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-09-30

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

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

International Nuclear Information System (INIS)

Alabbasi, Alyaa; Liyanaarachchi, S.; Kannan, M. Bobby

2012-01-01

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

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.

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.

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

Directory of Open Access Journals (Sweden)

Buong Woei Chieng

2014-08-01

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

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.

Thermal expansion coefficient determination of polylactic acid using digital image correlation

Directory of Open Access Journals (Sweden)

Botean Adrian - Ioan

2018-01-01

Full Text Available This paper aims determining the linear thermal expansion coefficient (CTE of polylactic acid (PLA using an optical method for measuring deformations called digital image correlation method (DIC. Because PLA is often used in making many pieces with 3D printing technology, it is opportune to know this coefficient to obtain a higher degree of precision in the construction of parts and to monitor deformations when these parts are subjected to a thermal gradient. Are used two PLA discs with 20 and 40% degree of filling. In parallel with this approach was determined the linear thermal expansion coefficient (CTE for the copper cylinder on the surface of which are placed the two discs of PLA.

Thermal expansion coefficient determination of polylactic acid using digital image correlation

Science.gov (United States)

Botean, Adrian-Ioan

2018-02-01

This paper aims determining the linear thermal expansion coefficient (CTE) of polylactic acid (PLA) using an optical method for measuring deformations called digital image correlation method (DIC). Because PLA is often used in making many pieces with 3D printing technology, it is opportune to know this coefficient to obtain a higher degree of precision in the construction of parts and to monitor deformations when these parts are subjected to a thermal gradient. Are used two PLA discs with 20 and 40% degree of filling. In parallel with this approach was determined the linear thermal expansion coefficient (CTE) for the copper cylinder on the surface of which are placed the two discs of PLA.

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

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.

Soil Burial of Polylactic Acid/Paddy Straw Powder Biocomposite

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Noorulnajwa Diyana Yaacob

2015-12-01

Full Text Available The objective of this work was to study the biodegradability of polylactic acid (PLA/paddy straw powder (PSP biocomposites. Environmental degradation was evaluated by composting the biocomposite samples into the soil. Different techniques, including mechanical tests and scanning electron microscopy (SEM, were used to obtain a view of the degradation that occurred during the soil burial of the biocomposites. Results of the mechanical tests showed that an increasing content of PSP in the biocomposites decreased the tensile strength and elongation at break (EB, while it increased the modulus of elasticity after six months of exposure. Scanning electron microscopy on the surface after soil burial showed that the filler was poorly wetted by the matrix. This explains the reduction in tensile strength and the elongation at break after soil burial. Differential scanning calorimetry results indicated that the crystallinity of the biocomposites increased with longer composting periods.

Influence of different factors on the destruction of films based on polylactic acid and oxidized polyethylene

Science.gov (United States)

Podzorova, M. V.; Tertyshnaya, Yu. V.; Pantyukhov, P. V.; Shibryaeva, L. S.; Popov, A. A.; Nikolaeva, S.

2016-11-01

Influence of different environmental factors on the degradation of film samples based on polylactic acid and low density polyethylene with the addition of oxidized polyethylene was studied in this work. Different methods were used to find the relationship between degradation and ultraviolet, moisture, oxygen. It was found that the addition of oxidized polyethylene, used as a model of recycled polyethylene, promotes the degradation of blends.

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

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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.

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...

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.

New Polylactic Acid Composites Reinforced with Artichoke Fibers

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Luigi Botta

2015-11-01

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

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...

Tensile and morphology properties of PLA/LNR blends modified with maleic anhydride grafted-polylactic acid and -natural rubber

Science.gov (United States)

Ruf, Mohd Farid Hakim Mohd; Ahmad, Sahrim; Chen, Ruey Shan; Shahdan, Dalila; Zailan, Farrah Diyana

2018-04-01

This research was carried out to investigate the addition of grafted copolymers of maleic anhydride grafted-polylactic acid(PLA-g-MA) and maleic anhydride grafted-natural rubber (NR-g-MA) on the tensile and morphology properties of polylactic acid/ liquid natural rubber (PLA/LNR) blends. Prior to blend preparation, the PLA-g-MA and NR-g-MA was first self-synthesized using maleic anhydride (MA) and dicumyl peroxide (DCP) as initiator together with the PLA and NR respectively. The PLA/LNR, PLA/LNR/PLA-g-MA and PLA/LNR/NR-g-MA blends were prepared via melt-blending method. The loading of PLA-g-MA and NR-g-MA was varied by 5, 10 and 15 wt% respectively. The addition of PLA-g-MA led to increment in tensile strength with 5 and 10 wt% while NR-g-MA gives lower than controlled sample (PLA/LNR blend). Scanning electron microscope (SEM) showed the interaction of the components in the blends. The PLA/LNR compatibilized with PLA-g-MA and NR-g-MA shows greater dispersion and adhesion.

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

DEFF Research Database (Denmark)

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

2016-01-01

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

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

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

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

Science.gov (United States)

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-09-01

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

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

International Nuclear Information System (INIS)

Bee, Soo-Tueen; Ratnam, C.T.; Sin, Lee Tin; Tee, Tiam-Ting; Wong, Wai-Kien; Lee, Jiuun-Xiang; Rahmat, A.R.

2014-01-01

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

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

Science.gov (United States)

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

2014-10-31

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

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...

[An experimental study on a slow-release complex with rifampicin-polylactic-co-glycolic acid-calcium 
phosphate cement].

Science.gov (United States)

Wu, Jianhuang; Ding, Zhou; Lei, Qing; Li, Miao; Liang, Yan; Lu, Tao

2016-09-28

To prepare the slow-release complex with rifampicin (RFP)-polylactic-co-glycolic acid (PLGA)-calcium phosphate cement (CPC) (RFP-PLGA-CPC complex), and to study its physical and chemical properties and drug release properties in vitro.
 The emulsification-solvent evaporation method was adopted to prepare rifampicin polylactic acid-glycolic acid (RFP-PLGA) slow-release microspheres, which were divided into 3 groups: a calcium phosphate bone cement group (CPC group), a CPC embedded with RFP group (RFP-CPC group), and a PLGA slow-release microspheres carrying RFP and the self-curing CPC group (RFP- PLGA-CPC complex group). The solidification time and porosity of materials were determined. The drug release experiments in vitro were carried out to observe the compressive strength, the change of section morphology before and after drug release. 
 The CPC group showed the shortest solidification time, while the RFP-PLGA-CPC complex group had the longest one. There was statistical difference in the porosity between the CPC group and the RFP-CPC group (Pbehavior of the complex, which was in accordance with zero order kinetics equation F=0.168×t.
 The porosity of RFP-PLGA-CPC complex is significantly higher than that of CPC, and it can keep slow release of the effective anti-tuberculosis drugs and maintain a certain mechanical strength for a long time.

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.

Thermal and Electrical Investigation of Conductive Polylactic Acid Based Filaments

Science.gov (United States)

Dobre, R. A.; Marcu, A. E.; Drumea, A.; Vlădescu, M.

2018-06-01

Printed electronics gain momentum as the involved technologies become affordable. The ability to shape electrostatic dissipative materials in almost any form is useful. The idea to use a general-purpose 3D printer to manufacture the electrical interconnections for a circuit is very attractive. The advantage of using a 3D printed structure over other technologies are mainly the lower price, less requirements concerning storage and use conditions, and the capability to build thicker traces while maintaining flexibility. The main element allowing this to happen is a printing filament with conductive properties. The paper shows the experiments that were performed to determine the thermal and electrical properties of polylactic acid (PLA) based ESD dissipative filament. Quantitative results regarding the thermal behavior of the DC resistance and the variation of the equivalent parallel impedance model parameters (losses resistance, capacitance, impedance magnitude and phase angle) with frequency are shown.. Using these results, new applications like printed temperature sensors can be imagined.

[Polylactic acid injections: usefullness for the treatment of facial lipoatrophy in HIV+ patients under tritherapy].

Science.gov (United States)

Piquet, M; Brignol, L; Chatelain, B; Rey, D; Ricbourg, B; Meyer, C

2007-12-01

The aim of the study was to evaluate the mean-term efficacy and tolerance of the polylactic acid injections (New-Fill) for the correction of facial lipoatrophy occurring in HIV-positive patients under tri-therapy. The patients were managed at the University Hospitals of Besançon and Strasbourg (France) from January 2002 to December 2005 for a prospective study. The patients were consecutively included in this study once their consent was obtained. Patients not stabilized by their antiretroviral treatment were excluded. Facial lipoatrophy was classified in four clinical stages (stage I: mild, stage II: moderate, stage III: important, stage IV: severe) after a clinical examination. The polylactic acid solution was prepared according to the manufacturer's recommendations, and injected in a retrotracing manner in the hypoderm at the rate of one 5 ml flask per side, with an interval of one month. The number of sessions varied according to the severity of the stage. Treatment efficacy, assessed after a minimal follow-up of one year, was established clinically by comparing the initial and final photographs (changes in the clinical stage) and by the patient's and surgeon's satisfaction rate (from zero to ten). Treatment tolerance was established on the painfulness of injections and on socioprofessional constraints reported by the patients and made on a visual analogical scale. The occurrence of adverse-effects was checked. Finally, we compared the cost of the treatment with that of lipostructure. Twenty-five patients were included (mean age: 44, sex-ratio: 23 male/2 female patients). The mean body mass index was 21. The mean CD4 cell count was 600/mm(3). The mean HIV-1 RNA was 276 copies/ml. The severity of the lipoatrophy was stage one in two patients (8%), stage two in 12 patients (48%), stage three in nine patients (36%), and stage four in two patients (8%). The mean number of sessions was 5.2. The mean follow-up time was 26 months. In 76% of the cases we observed a

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...

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.

Science.gov (United States)

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

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

Directory of Open Access Journals (Sweden)

Javed Alam

2014-10-01

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

The selective recycling of mixed plastic waste of polylactic acid and polyethylene terephthalate by control of process conditions

OpenAIRE

Carné Sánchez, Arnau; Collinson, Simon R.

2011-01-01

The glycolysis of postconsumer polyethylene terephthalate (PET) waste was evaluated with catalysts of zinc acetate, zinc stearate and zinc sulfate, showing that zinc acetate was the most soluble and effective. The chemical recycling by solvolysis of polylactic acid (PLA) and PET waste in either methanol or ethanol was investigated. Zinc acetate as a catalyst was found to be necessary to yield an effective depolymerization of waste PLA giving lactate esters, while with the same reaction condit...

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...

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.

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

Directory of Open Access Journals (Sweden)

Georg Steinkellner

2012-02-01

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

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

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

Science.gov (United States)

Canetti, Maurizio; Cacciamani, Adriana; Bertini, Fabio

2016-05-01

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

Development of polylactic acid nanocomposite films reinforced with cellulose nanocrystals derived from coffee silverskin.

Science.gov (United States)

Sung, Soo Hyun; Chang, Yoonjee; Han, Jaejoon

2017-08-01

Bio-nanocomposite films based on polylactic acid (PLA) matrix reinforced with cellulose nanocrystals (CNCs) were developed using a twin-screw extruder. The CNCs were extracted from coffee silverskin (CS), which is a by-product of the coffee roasting process. They were extracted by alkali treatment followed by sulfuric acid hydrolysis. They were used as reinforcing agents to obtain PLA/CNC nanocomposites by addition at different concentrations (1%, 3%, and 5% CNCs). Morphological, tensile, and barrier properties of the bio-nanocomposites were analyzed. The tensile strength and Young's modulus increased with both 1% and 3% CNCs. The water vapor permeability decreased gradually with increasing addition of CNCs up to 3% and good oxygen barrier properties were found for all nanocomposites. These results suggest that CNCs from CS can improve the physical properties of PLA-based biopolymer film. The developed PLA/CNC bio-nanocomposite films can potentially be used for biopolymer materials with enhanced barrier and mechanical properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancement of uranyl fluorescence using trimesic acid: Ligand sensitization and co-fluorescence

Energy Technology Data Exchange (ETDEWEB)

Maji, S. [Chemistry Group, Materials Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Viswanathan, K.S., E-mail: vish@igcar.gov.in [Chemistry Group, Materials Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2011-09-15

Trimesic acid (TMA) was shown to sensitize and enhance uranyl fluorescence in aqueous medium, with the enhancement being a maximum at pH 5.0. Fluorescence spectra and lifetime data together suggest that TMA complexes with uranyl (UO{sub 2}{sup 2+}). The fluorescence of UO{sub 2}{sup 2+} in its acid complex is further enhanced by more than two orders of magnitude following the addition of Y{sup 3+}; a process referred to as co-fluorescence, leading to the possibility of detecting uranium at sub ng/mL level. The present study demonstrates, for the first time, fluorescence enhancement of the uranyl species due to co-fluorescence. - Highlights: > Trimesic acid was shown to sensitize and enhance the fluorescence of uranium in aqueous medium. > This ligand also exhibited co-fluorescence of uranium with Y{sup 3+}. > To the best of our knowledge this is the first report of co-fluorescence in uranium. > The enhancement of uranium fluorescence, resulted in detection limits in the ng/mL regime.

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-11-15

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

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.

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

International Nuclear Information System (INIS)

Li Fengxia; Li Xiaoli; Li Bin

2011-01-01

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

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.

Dielectric Properties of 3D Printed Polylactic Acid

Directory of Open Access Journals (Sweden)

Claudius Dichtl

2017-01-01

Full Text Available 3D printers constitute a fast-growing worldwide market. These printers are often employed in research and development fields related to engineering or architecture, especially for structural components or rapid prototyping. Recently, there is enormous progress in available materials for enhanced printing systems that allow additive manufacturing of complex functional products, like batteries or electronics. The polymer polylactic acid (PLA plays an important role in fused filament fabrication, a technique used for commercially available low-budget 3D printers. This printing technology is an economical tool for the development of functional components or cases for electronics, for example, for lab purposes. Here we investigate if the material properties of “as-printed” PLA, which was fabricated by a commercially available 3D printer, are suitable to be used in electrical measurement setups or even as a functional material itself in electronic devices. For this reason, we conduct differential scanning calorimetry measurements and a thorough temperature and frequency-dependent analysis of its dielectric properties. These results are compared to partially crystalline and completely amorphous PLA, indicating that the dielectric properties of “as-printed” PLA are similar to the latter. Finally, we demonstrate that the conductivity of PLA can be enhanced by mixing it with the ionic liquid “trihexyl tetradecyl phosphonium decanoate.” This provides a route to tailor PLA for complex functional products produced by an economical fused filament fabrication.

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

Directory of Open Access Journals (Sweden)

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.

Thermal Stability and Surface Wettability Studies of Polylactic Acid/Halloysite Nanotube Nanocomposite Scaffold for Tissue Engineering Studies

Science.gov (United States)

Nizar, M. Mohd; Hamzah, M. S. A.; Razak, S. I. Abd; Mat Nayan, N. H.

2018-03-01

This paper reports the preliminary study about the incorporation of halloysite nanotubes (HNT) into polylactic acid (PLA) scaffold to improve the thermal resistance and surface wettability properties. The fabrication of the porous scaffold requires a simple yet effective technique with low-cost materials within freeze extraction method. The thermal stability of PLA/HNT scaffold compared to neat PLA scaffold achieved with increased content of HNT by 5 wt%. Moreover, the surface wettability of the scaffold also shows a positive impact with high content of HNT by 5 wt%. This new nanocomposite scaffold may have high potential as a suitable template for tissue regeneration.

Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model

OpenAIRE

Zhang, Haifeng; Mao, Xiyuan; Du, Zijing; Jiang, Wenbo; Han, Xiuguo; Zhao, Danyang; Han, Dong; Li, Qingfeng

2016-01-01

Abstract We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500??m and 60% porosity was fabricated by three-dimensional printing. Three-dimensional printed PLA/HA, ?-tricalcium phosphate (?-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, prolife...

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.

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

International Nuclear Information System (INIS)

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)

Antibacterial polylactic acid/chitosan nanofibers decorated with bioactive glass

Energy Technology Data Exchange (ETDEWEB)

Goh, Yi-fan; Akram, Muhammad; Alshemary, Ammarz [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Hussain, Rafaqat, E-mail: rafaqat@comsats.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

2016-11-30

Highlights: • PLA/Chitosan nanofibers were coated with functional bioglass. • Polymer/ceramic composite fibers exhibited good in-vitro bioactivity. • Nanofibers coated with Ag doped bioglass exhibited good antibacterial activity. - Abstract: In this study, we have presented the structural and in vitro characterization of electrospun polylactic acid (PLA)/Chitosan nanofibers coated with cerium, copper or silver doped bioactive glasses (CeBG/CuBG/AgBG). Bead-free, smooth surfaced nanofibers were successfully prepared by using electrospinning technique. The nanocomposite fibers were obtained using a facile dip-coating method, their antibacterial activities against E. coliE. coli (ATCC 25922 strains) were measured by the disk diffusion method after 24 h of incubation at 37 °C. CeBG and CuBG decorated PLA/Chitosan nanofibers did not develop an inhibition zone against the bacteria. On the other hand, nanofibers coated with AgBG developed an inhibition zone against the bacteria. The as-prepared nanocomposite fibers were immersed in SBF for 1, 3 and 7 days in Simulated Body Fluid (SBF) for evaluation of in vitro bioactivity. All samples induced the formation of crystallites with roughly ruffled morphology and the pores of fibers were covered with the extensive growth of crystallites. Energy Dispersive X-ray (EDX) composition analysis showed that the crystallites possessed Ca/P ratio close to 1.67, confirming the good in-vitro bioactivity of the fibers.

Polylactic acid (PLA) controlled delivery carriers for biomedical applications.

Science.gov (United States)

Tyler, Betty; Gullotti, David; Mangraviti, Antonella; Utsuki, Tadanobu; Brem, Henry

2016-12-15

Polylactic acid (PLA) and its copolymers have a long history of safety in humans and an extensive range of applications. PLA is biocompatible, biodegradable by hydrolysis and enzymatic activity, has a large range of mechanical and physical properties that can be engineered appropriately to suit multiple applications, and has low immunogenicity. Formulations containing PLA have also been Food and Drug Administration (FDA)-approved for multiple applications making PLA suitable for expedited clinical translatability. These biomaterials can be fashioned into sutures, scaffolds, cell carriers, drug delivery systems, and a myriad of fabrications. PLA has been the focus of a multitude of preclinical and clinical testing. Three-dimensional printing has expanded the possibilities of biomedical engineering and has enabled the fabrication of a myriad of platforms for an extensive variety of applications. PLA has been widely used as temporary extracellular matrices in tissue engineering. At the other end of the spectrum, PLA's application as drug-loaded nanoparticle drug carriers, such as liposomes, polymeric nanoparticles, dendrimers, and micelles, can encapsulate otherwise toxic hydrophobic anti-tumor drugs and evade systemic toxicities. The clinical translation of these technologies from preclinical experimental settings is an ever-evolving field with incremental advancements. In this review, some of the biomedical applications of PLA and its copolymers are highlighted and briefly summarized. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of Polylactic Acid/ Microcrystalline Cellulose/ Montmorillonite Hybrid Composites

International Nuclear Information System (INIS)

Reza Arjmandi; Azman Hassan; Haafiz, M.K.M.; Zainoha Zakaria; Inuwa, I.M.

2014-01-01

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

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

International Nuclear Information System (INIS)

Jung, Ui-Won; Song, Kun-Young; Kim, Chang-Sung; Lee, Yong-Keun; Cho, Kyoo-Sung; Kim, Chong-Kwan; Choi, Seong-Ho

2007-01-01

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

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...

Novel toughened polylactic acid nanocomposite: Mechanical, thermal and morphological properties

International Nuclear Information System (INIS)

Balakrishnan, Harintharavimal; Hassan, Azman; Wahit, Mat Uzir; Yussuf, A.A.; Razak, Shamsul Bahri Abdul

2010-01-01

The objective of the study is to develop a novel toughened polylactic acid (PLA) nanocomposite. The effects of linear low density polyethylene (LLDPE) and organophilic modified montmorillonite (MMT) on mechanical, thermal and morphological properties of PLA were investigated. LLDPE toughened PLA nanocomposites consisting of PLA/LLDPE blends, of composition 100/0 and 90/10 with MMT content of 2 phr and 4 phr were prepared. The Young's and flexural modulus improved with increasing content of MMT indicating that MMT is effective in increasing stiffness of LLDPE toughened PLA nanocomposite even at low content. LLDPE improved the impact strength of PLA nanocomposites with a sacrifice of tensile and flexural strength. The tensile and flexural strength also decreased with increasing content of MMT in PLA/LLDPE nanocomposites. The impact strength and elongation at break of LLDPE toughened PLA nanocomposites also declined steadily with increasing loadings of MMT. The crystallization temperature and glass transition temperature dropped gradually while the thermal stability of PLA improved with addition of MMT in PLA/LLDPE nanocomposites. The storage modulus of PLA/LLDPE nanocomposites below glass transition temperature increased with increasing content of MMT. X-ray diffraction and transmission electron microscope studies revealed that an intercalated LLDPE toughened PLA nanocomposite was successfully prepared at 2 phr MMT content.

Biodegradable packaging materials conception based on starch and polylactic acid (PLA) reinforced with cellulose.

Science.gov (United States)

Masmoudi, Fatma; Bessadok, Atef; Dammak, Mohamed; Jaziri, Mohamed; Ammar, Emna

2016-10-01

The plastic materials used for packaging are increasing leading to a considerable amount of undegradable solid wastes. This work deals with the reduction of conventional plastics waste and the natural resources preservation by using cellulosic polymers from renewable resources (alfa and luffa). Plasticized starch films syntheses were achieved at a laboratory scale. These natural films showed some very attractive mechanical properties at relatively low plasticizers levels (12 to 17 % by weight). Furthermore, mixtures including polylactic acid polymer (PLA) and cellulose fibers extracted from alfa and luffa were investigated by melt extrusion technique. When used at a rate of 10 %, these fibers improved the mixture mechanical properties. Both developed materials were biodegradable, but the plasticized starch exhibited a faster biodegradation kinetic compared to the PLA/cellulose fibers. These new materials would contribute to a sustainable development and a waste reduction.

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.

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.

Modelling of photodegradation effect on elastic-viscoplastic behaviour of amorphous polylactic acid films

Science.gov (United States)

Belbachir, S.; Zaïri, F.; Ayoub, G.; Maschke, U.; Naït-Abdelaziz, M.; Gloaguen, J. M.; Benguediab, M.; Lefebvre, J. M.

2010-02-01

Polylactic acid (PLA) films were subjected to accelerated ultra-violet (UV) ageing. The UV irradiation leads to the alteration of the chemical structure which influences directly the mechanical response of the polymer. The chemical modification of the polymer was followed by gel permeation chromatography. Uniaxial tension tests were conducted at 50 °C and for different strain rates in order to characterize the large deformation response of PLA. The influence of UV irradiation on the alteration of the large deformation response of PLA was examined. A physically based elastic-viscoplastic model was used to describe the mechanical response of virgin PLA. The photodegradation effect was incorporated into the constitutive model to capture the stress-strain behaviour up to failure of aged PLA. To that end, the measured molecular weight was used as a direct input into the model. The model is shown to be in good agreement with experimental results over a wide range of UV irradiation doses.

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.

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.

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

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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.

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.

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.

Characterization and properties of acetylated nanocrystalline cellulose (aNC) reinforced polylactic acid (PLA) polymer

Science.gov (United States)

Kasa, Siti Norbaya; Omar, Mohd Firdaus; Ismail, Ismarul Nizam

2017-12-01

Nanocrystalline cellulose (NCC) was synthesized from banana stem through strong acid hydrolysis with measured length of approximately 287.0 ± 56.4 nm and diameter of 26.6 ± 4.8 nm. Modification of NCC was carried by acetylation reaction in order to increase the compatibility during reinforcement with polylactic acid (PLA) polymer. The reinforcing effect towards morphology, crystallinity, mechanical and thermal properties of bio-nanocomposites was investigated. Scanning Electron Microscope (SEM) micrograph reveals the uniform dispersion achieved at 1 %, 3 % and 5% aNC loading while agglomeration was found at 7 % aNC loading. Disappearance of crystallinity peak at 2θ = 22.7⁰ for low aNC loading during elemental analysis using X-Ray Diffraction (XRD) indicates the proper dispersion of aNC in PLA polymer. From the tensile test, 1 % aNC loading gives the highest mechanical properties of bio-nanocomposite film with 82.71 %, 118.7 % and 24.18 % increment in tensile strength, tensile modulus and elongation at break. However, 7 % aNC loading gives the highest increment in TGA of aNC-PLA nanocomposites which is from 310 °C to 320 °C.

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

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

Energy Technology Data Exchange (ETDEWEB)

Salerno, Aurelio, E-mail: asalerno@unina.it [Centre for Advanced Biomaterials for Health Care, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, 80125 Napoli (Italy); Institute of Materials Science of Barcelona (ICMAB-CSIC), Campus de la UAB s/n, Bellaterra 08193 (Spain); Guarino, Vincenzo; Oliviero, Olimpia; Ambrosio, Luigi [Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, V.le Kennedy 54, Pad 20, Mostra d' Oltremare, 80125 Naples (Italy); Domingo, Concepción [Institute of Materials Science of Barcelona (ICMAB-CSIC), Campus de la UAB s/n, Bellaterra 08193 (Spain)

2016-06-01

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

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 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.

Enhancement of the Mechanical Properties of a Polylactic Acid/Flax Fiber Biocomposite by WPU, WPU/Starch, and TPS Polyurethanes Using Coupling Additives

Science.gov (United States)

Miskolczi, N.; Sedlarik, V.; Kucharczyk, P.; Riegel, E.

2018-01-01

This work is addressed to the synthesis of bio-based polymers and investigation of their application in a flax-fiber-reinforced polylactic acid. Polyurethane polymers were synthesized from polyphenyl-methane-diisocyanate, poly (ethylene oxide) glycol, and ricinoleic acid, and their structure was examined by the Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. It was established that the introduction of flax fibers and different compatibilizers into the polymers improved their mechanical properties. A vinyl-trimetoxy-silane and polyalkenyl-polymaleic-anhydride derivative with a high acid number produced the best effect on the properties, but samples without additives had the highest water absorption capacity. SEM micrographs showed a good correlation between the morphology of fracture structure of the composites and the mechanical properties of flax fibers.

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

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

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.

Fabrication of high-performance poly(l-lactic acid)/lignin-graft-poly(d-lactic acid) stereocomplex films.

Science.gov (United States)

Liu, Rui; Dai, Lin; Hu, Li-Qiu; Zhou, Wen-Qin; Si, Chuan-Ling

2017-11-01

The need for green renewable alternatives such as lignin to traditional fillers has driven recent interest in polylactic acid blend materials. Herein, lignin-graft-polylactic acid copolymers (LG-g-PDLA, LG-g-PDLLA, and LG-g-PLLA) have been synthesized via ring-opening polymerization of d-, dl-, and l-lactic acid. Then poly(l-lactic acid)/lignin-graft-polylactic acid (PLLA/LG-g-PDLA, /LG-g-PDLLA, and /LG-g-PLLA) complex films have been prepared. The results showed that, compared with LG-g-PDLA and LG-g-PLLA, a small amount of LG-g-PDLA addition could improve the crystallization rate, reduce the glass transition temperature and cold crystallization temperature of PLLA due to the stereocomplex crystallites. The thermal stability, tensile strength and strain of the stereocomplex films were also enhanced. Moreover, the PLLA/LG-g-PDLA films have good ultraviolet resistance and excellent biocompatibility. This study provides a green approach to design advanced polylactic acid-based blends with renewable natural resources. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Directory of Open Access Journals (Sweden)

D. E. Garcia

2016-10-01

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

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

Science.gov (United States)

Liu, Xingxun; Wang, Tongxin; Chow, Laurence C; Yang, Mingshu; Mitchell, James W

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

Low molecular weight polylactic acid as a matrix for the delayed release of pesticides.

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Zhao, Jing; Wilkins, Richard M

2005-05-18

Low molecular weight polylactic acid (LMW PLA) was used as a matrix to formulate biodegradable matrix granules and films with bromacil using a melt process. The compatibility of the PLA with bromacil was evaluated. The release characteristics of the formulations were investigated in vitro. The degradation and erosion of the formulations were monitored by pH and gravimetric analysis during the course of release. Various granules and films had similar biphasic release patterns, a delayed release followed by an explosive release. The release rates were independent of bromacil content in the matrix, but varied with the geometry of matrices. The mechanisms of diffusion and erosion were involved in the release. The delayed release of the formulations was dominantly governed by the degradation and erosion of PLA. LMW PLA underwent bulk erosion. LMW PLA-based matrix formulations could thus be useful for the application of pesticides to sensitive targets such as seed treatment.

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

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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

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

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Xingxun Liu

2014-01-01

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

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

Effect of Rhizopus oryzae Fermentation on Kenaf-Based Polylactic Acid’s Monomer

OpenAIRE

Nur Aimi Mohd Nasir; Mohd Adlan Mustafa Kamalbahrin; Nurhafizah Mohamad; Hazleen Anuar; Maizirwan Mel; and Rashidi Othman

2011-01-01

Kenaf biomass is the potential as raw materials used to produce polylactic acid's monomer which is lactic acid via fermentation by Rhizopus oryzae. Kenaf biomass' structure is complex due to its lignin and cellulose content. This matter had encouraged it to undergo pre- treatment process as the initial step before fermentation process can be done. In this paper, kenaf biomass was treated with dilute sulphuric acid (H2SO4) to hydrolyze the cellulose content in it as well as to convert the cell...

Polymer Film-Based Screening and Isolation of Polylactic Acid (PLA)-Degrading Microorganisms.

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Kim, Mi Yeon; Kim, Changman; Moon, Jungheun; Heo, Jinhee; Jung, Sokhee P; Kim, Jung Rae

2017-02-28

Polylactic acid (PLA) has been highlighted as an alternative renewable polymer for the replacement of petroleum-based plastic materials, and is considered to be biodegradable. On the other hand, the biodegradation of PLA by terminal degraders, such as microorganisms, requires a lengthy period in the natural environment, and its mechanism is not completely understood. PLA biodegradation studies have been conducted using mainly undefined mixed cultures, but only a few bacterial strains have been isolated and examined. For further characterization of PLA biodegradation, in this study, the PLA-degrading bacteria from digester sludge were isolated and identified using a polymer film-based screening method. The enrichment of sludge on PLA granules was conducted with the serial transference of a subculture into fresh media for 40 days, and the attached biofilm was inoculated on a PLA film on an agar plate. 3D optical microscopy showed that the isolates physically degraded the PLA film due to bacterial degradation. 16S rRNA gene sequencing identified the microbial colonies to be Pseudomonas sp. MYK1 and Bacillus sp. MYK2. The two isolates exhibited significantly higher specific gas production rates from PLA biodegradation compared with that of the initial sludge inoculum.

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.

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

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

2010-11-01

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

Natamycin based sol-gel antimicrobial coatings on polylactic acid films for food packaging.

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Lantano, Claudia; Alfieri, Ilaria; Cavazza, Antonella; Corradini, Claudio; Lorenzi, Andrea; Zucchetto, Nicola; Montenero, Angelo

2014-12-15

In this work a comprehensive study on a new active packaging obtained by a hybrid organic-inorganic coating with antimicrobial properties was carried out. The packaging system based on polylactic acid was realised by sol-gel processing, employing tetraethoxysilane as a precursor of the inorganic phase and polyvinyl alcohol as the organic component, and incorporating natamycin as the active agent. Films with different organic-inorganic ratios (in a range between 1:19 and 1:4) were prepared, and the amount of antimycotic entrapped was found to be modulated by the sol composition, and was between 0.18 and 0.25mg/dm(2). FTIR microspectroscopic measurements were used to characterise the prepared coatings. The antifungal properties of the films were investigated against mould growth on the surface of commercial semi-soft cheese. The release of natamycin from the films to ethanol 50% (v/v) was studied by means of HPLC UV-DAD. The maximal level released was about 0.105 mg/dm(2), which is far below the value allowed by legislation. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

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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 

Selective fluorescent detection of aspartic acid and glutamic acid employing dansyl hydrazine dextran conjugate.

Science.gov (United States)

Nasomphan, Weerachai; Tangboriboonrat, Pramuan; Tanapongpipat, Sutipa; Smanmoo, Srung

2014-01-01

Highly water soluble polymer (DD) was prepared and evaluated for its fluorescence response towards various amino acids. The polymer consists of dansyl hydrazine unit conjugated into dextran template. The conjugation enhances higher water solubility of dansyl hydrazine moiety. Of screened amino acids, DD exhibited selective fluorescence quenching in the presence of aspartic acid (Asp) and glutamic acid (Glu). A plot of fluorescence intensity change of DD against the concentration of corresponding amino acids gave a good linear relationship in the range of 1 × 10(-4) M to 25 × 10(-3) M. This establishes DD as a potential polymeric sensor for selective sensing of Asp and Glu.

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.

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

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Chul B. Park

2009-12-01

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

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.

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.

Cellular reactions to three-dimensional matrices of polylactic acid and hydroxyapatite generated by 3D-printing

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T. V. Druzhinina

2016-01-01

Full Text Available The purpose of this study is to estimate Ex vivo physicochemical and biological features of three-dimensional (3D biodegradable matrices “polylactic acid/calcium phosphates” (hereafter 3D composites designed with the help of additive technologies (3D printing as potential materials for bone tissue regeneration.Materials and methods. Experimental samples (disks 1,2–1,6 mm thick, and 11 mm or 8 mm in diameter of composite biodegradable 3D matrices (hereafter 3D composites have been produced from initial mixture of 95 mas% polylactic acid (PLA and 5 mas% hydroxyapatite (HAP. Computer-aided design method, Blender software and fused filament fabrication (FFF; fiber diameter 1,75 mm with 3D printing were used in sample production. 100 mas% PLA disks served as control. One of the sample surfaces was textured with 0,3–0,5 mm wide grooves. Physicochemical properties of 11 mm disks (geometry, mass, morphology, roughness, electrostatic voltage, surface wettability, and element composition were studied. Biological trials included the evaluation of 24-hour cytotoxicity of 8 mm samples in culture of mononuclear leukocytes of a healthy volunteer or human Jurkat T cell leukemia-derived cell line (hereafter Jurkat T cells. Moreover, osteogenic potential of 11 mm disks was determined in 21-day culture of human adipose-derived multipotent mesenchymal stem cells (AMMSCs be means of osteocalcin secretion and intercellular matrix mineralization visualized by alizarin red S staining.Results. The features of PLA-HAP 3D composites generated by 3D printing correspond to physicochemical parameters which are crucial for bone tissue recovery. In case of small amount of calcium and phosphorus they facilitated ex vivo mineralization of extracellular matrix formed in AMMSCs culture. The number of died (by necrosis, mainly leukemic Jurkat T cells but not mononuclear leukocytes of a health volunteer increased to 9–10% in 24-hour in vitro contact with PLA-HAP 3D

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

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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.

Bamboo-Polylactic Acid (PLA) Composite Material for Structural Applications.

Science.gov (United States)

Pozo Morales, Angel; Güemes, Alfredo; Fernandez-Lopez, Antonio; Carcelen Valero, Veronica; De La Rosa Llano, Sonia

2017-11-09

Developing an eco-friendly industry based on green materials, sustainable technologies, and optimum processes with low environmental impact is a general societal goal, but this remains a considerable challenge to achieve. Despite the large number of research on green structural composites, limited investigation into the most appropriate manufacturing methodology to develop a structural material at industrial level has taken place. Laboratory panels have been manufactured with different natural fibers but the methodologies and values obtained could not be extrapolated at industrial level. Bamboo industry panels have increased in the secondary structural sector such as building application, flooring and sport device, because it is one of the cheapest raw materials. At industrial level, the panels are manufactured with only the inner and intermediate region of the bamboo culm. However, it has been found that the mechanical properties of the external shells of bamboo culm are much better than the average cross-sectional properties. Thin strips of bamboo (1.5 mm thick and 1500 mm long) were machined and arranged with the desired lay-up and shape to obtain laminates with specific properties better than those of conventional E-Glass/Epoxy laminates in terms of both strength and stiffness. The strips of bamboo were bonded together by a natural thermoplastic polylactic acid (PLA) matrix to meet biodegradability requirements. The innovative mechanical extraction process developed in this study can extract natural strip reinforcements with high performance, low cost, and high rate, with no negative environmental impact, as no chemical treatments are used. The process can be performed at the industrial level. Furthermore, in order to validate the structural applications of the composite, the mechanical properties were analyzed under ageing conditions. This material could satisfy the requirements for adequate mechanical properties and life cycle costs at industrial sectors such

Bamboo–Polylactic Acid (PLA Composite Material for Structural Applications

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Angel Pozo Morales

2017-11-01

Full Text Available Developing an eco-friendly industry based on green materials, sustainable technologies, and optimum processes with low environmental impact is a general societal goal, but this remains a considerable challenge to achieve. Despite the large number of research on green structural composites, limited investigation into the most appropriate manufacturing methodology to develop a structural material at industrial level has taken place. Laboratory panels have been manufactured with different natural fibers but the methodologies and values obtained could not be extrapolated at industrial level. Bamboo industry panels have increased in the secondary structural sector such as building application, flooring and sport device, because it is one of the cheapest raw materials. At industrial level, the panels are manufactured with only the inner and intermediate region of the bamboo culm. However, it has been found that the mechanical properties of the external shells of bamboo culm are much better than the average cross-sectional properties. Thin strips of bamboo (1.5 mm thick and 1500 mm long were machined and arranged with the desired lay-up and shape to obtain laminates with specific properties better than those of conventional E-Glass/Epoxy laminates in terms of both strength and stiffness. The strips of bamboo were bonded together by a natural thermoplastic polylactic acid (PLA matrix to meet biodegradability requirements. The innovative mechanical extraction process developed in this study can extract natural strip reinforcements with high performance, low cost, and high rate, with no negative environmental impact, as no chemical treatments are used. The process can be performed at the industrial level. Furthermore, in order to validate the structural applications of the composite, the mechanical properties were analyzed under ageing conditions. This material could satisfy the requirements for adequate mechanical properties and life cycle costs at

Bamboo–Polylactic Acid (PLA) Composite Material for Structural Applications

Science.gov (United States)

Pozo Morales, Angel; Güemes, Alfredo; Fernandez-Lopez, Antonio; Carcelen Valero, Veronica; De La Rosa Llano, Sonia

2017-01-01

Developing an eco-friendly industry based on green materials, sustainable technologies, and optimum processes with low environmental impact is a general societal goal, but this remains a considerable challenge to achieve. Despite the large number of research on green structural composites, limited investigation into the most appropriate manufacturing methodology to develop a structural material at industrial level has taken place. Laboratory panels have been manufactured with different natural fibers but the methodologies and values obtained could not be extrapolated at industrial level. Bamboo industry panels have increased in the secondary structural sector such as building application, flooring and sport device, because it is one of the cheapest raw materials. At industrial level, the panels are manufactured with only the inner and intermediate region of the bamboo culm. However, it has been found that the mechanical properties of the external shells of bamboo culm are much better than the average cross-sectional properties. Thin strips of bamboo (1.5 mm thick and 1500 mm long) were machined and arranged with the desired lay-up and shape to obtain laminates with specific properties better than those of conventional E-Glass/Epoxy laminates in terms of both strength and stiffness. The strips of bamboo were bonded together by a natural thermoplastic polylactic acid (PLA) matrix to meet biodegradability requirements. The innovative mechanical extraction process developed in this study can extract natural strip reinforcements with high performance, low cost, and high rate, with no negative environmental impact, as no chemical treatments are used. The process can be performed at the industrial level. Furthermore, in order to validate the structural applications of the composite, the mechanical properties were analyzed under ageing conditions. This material could satisfy the requirements for adequate mechanical properties and life cycle costs at industrial sectors such

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

Science.gov (United States)

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.

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.

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.

Influence of Maleic Anhydride/Glycidyl Methacrylate Cografted Polylactic Acid on Properties of Wood Flour/PLA Composites

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DU Jun

2017-12-01

Full Text Available Graft copolymers of PLA-g-MAH, PLA-g-GMA and PLA-co-MAH/GMA were prepared by means of melt grafting. The structure of the graft copolymers were characterized by FTIR.Wood flour/PLA composites were prepared by injection molding with three kinds of graft copolymers as compatibilizers, and the fractured morphology of composites was investigated by scanning electron microscope (SEM. Results show that there is no obvious phase interface between wood flour and PLA,which indicating the interfacial compatibility of wood flour/PLA composites is improved after adding different graft copolymers. The determination results of mechanical properties, processing flowability and dynamic rheological property of composites prepared with different graft copolymers reveal that, compared to the composite without compatibilizer, the tensile strength and impact strength of wood flour/PLA composites are increased by 9.54% and 7.23% respectively, and the equilibrium torque, shear heat, storage modulus and complex viscosity are all increased after adding maleic anhydride/glycidyl methacrylate cografted polylactic acid.

Preparation and Characterization of an Olive Flounder (Paralichthys olivaceus) Skin Gelatin and Polylactic Acid Bilayer Film.

Science.gov (United States)

Lee, Ka-Yeon; Song, Kyung Bin

2017-03-01

Olive flounder skin gelatin (OSG) was used as a film base material. A bilayer film of OSG and polylactic acid (PLA) was prepared using solvent casting method to enhance the film properties. Physical properties of the OSG-PLA film were increased compared with the nonaugmented OSG film. In particular, the PLA lamination decreased water vapor permeability from 2.17 to 0.92 × 10 -9 g·m/m 2 ·s·Pa, as well as of the water solubility from 16.62% to 9.27%, in the bilayer film relative to the OSG film. The oxygen permeability of the OSG-PLA bilayer film was held low by the OSG film, compensating for the high oxygen permeability of the PLA layer. Therefore, the OSG-PLA bilayer film with its enhanced physical properties and high water and oxygen barrier properties can be applied as a food packaging material. © 2017 Institute of Food Technologists®.

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

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Du Y

2015-05-01

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

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

Science.gov (United States)

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

2012-09-01

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

"Clickable" LNA/DNA probes for fluorescence sensing of nucleic acids and autoimmune antibodies

DEFF Research Database (Denmark)

Jørgensen, Anna S; Gupta, Pankaj; Wengel, Jesper

2013-01-01

Herein we describe fluorescent oligonucleotides prepared by click chemistry between novel alkyne-modified locked nucleic acid (LNA) strands and a series of fluorescent azides for homogeneous (all-in-solution) detection of nucleic acids and autoimmune antibodies.......Herein we describe fluorescent oligonucleotides prepared by click chemistry between novel alkyne-modified locked nucleic acid (LNA) strands and a series of fluorescent azides for homogeneous (all-in-solution) detection of nucleic acids and autoimmune antibodies....

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.

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.

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.

Processing and Characterisation of the Copper Treated Polylactic Acid and Cotton Fabrics: Thermophysiological Comfort Properties

Directory of Open Access Journals (Sweden)

Muhammet UZUN

2014-04-01

Full Text Available The main objective of this study is to develop a novel copper treatment method and characterise the effect of treatment on the thermophysiological comfort properties of the treated fabrics. It is also aimed to analyse and evaluate the thermophysiological properties of the PLA fabrics. The study was conducted by using polylactic acid (PLA, cotton and their blend yarns. The knitted fabrics, single pique, were made from these yarns by using weft knitting machine. The fabrics were treated with two copper solution concentrations (5 % and 10 % at 20 minutes ultrasonic energy. The results show that the treatment has a critical effect on the tested fabrics in terms of thermal conductivity, thermal resistance, thermal absorbtivity, water vapour permeability, and heat loss. The results also clearly demonstrated that the PLA fabric was successfully treated with the copper solution, and the coated fabrics showed significant change as compared to their untreated counterparts in terms of tested parameters.DOI: http://dx.doi.org/10.5755/j01.ms.20.1.1853

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

Directory of Open Access Journals (Sweden)

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.

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

Science.gov (United States)

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)

Energy Technology Data Exchange (ETDEWEB)

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.

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

Science.gov (United States)

Yang, Hyun-Ju; Song, Kyung Bin

2016-01-01

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

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

Science.gov (United States)

2016-01-01

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

Adaptive Evolution of Eel Fluorescent Proteins from Fatty Acid Binding Proteins Produces Bright Fluorescence in the Marine Environment.

Directory of Open Access Journals (Sweden)

David F Gruber

Full Text Available We report the identification and characterization of two new members of a family of bilirubin-inducible fluorescent proteins (FPs from marine chlopsid eels and demonstrate a key region of the sequence that serves as an evolutionary switch from non-fluorescent to fluorescent fatty acid-binding proteins (FABPs. Using transcriptomic analysis of two species of brightly fluorescent Kaupichthys eels (Kaupichthys hyoproroides and Kaupichthys n. sp., two new FPs were identified, cloned and characterized (Chlopsid FP I and Chlopsid FP II. We then performed phylogenetic analysis on 210 FABPs, spanning 16 vertebrate orders, and including 163 vertebrate taxa. We show that the fluorescent FPs diverged as a protein family and are the sister group to brain FABPs. Our results indicate that the evolution of this family involved at least three gene duplication events. We show that fluorescent FABPs possess a unique, conserved tripeptide Gly-Pro-Pro sequence motif, which is not found in non-fluorescent fatty acid binding proteins. This motif arose from a duplication event of the FABP brain isoforms and was under strong purifying selection, leading to the classification of this new FP family. Residues adjacent to the motif are under strong positive selection, suggesting a further refinement of the eel protein's fluorescent properties. We present a phylogenetic reconstruction of this emerging FP family and describe additional fluorescent FABP members from groups of distantly related eels. The elucidation of this class of fish FPs with diverse properties provides new templates for the development of protein-based fluorescent tools. The evolutionary adaptation from fatty acid-binding proteins to fluorescent fatty acid-binding proteins raises intrigue as to the functional role of bright green fluorescence in this cryptic genus of reclusive eels that inhabit a blue, nearly monochromatic, marine environment.

Degradation of polylactic acid (Pla) at different doses of gamma radiation

International Nuclear Information System (INIS)

Castillo R, Y.

2015-01-01

The excessive use of polymers such as polyethylene (PET), polystyrene (Ps) and recently the polylactic acid (Pla) that take more than 20 years to degrade, have caused great pollution in the environment. In this study the effects of gamma radiation in the Pla to different doses were studied, in order to reduce the degradation time of this polymer. The changes in physico-chemical structure of Pla during radiation were studied by thermo-gravimetric/Mass analysis; differential scanning calorimetry; scanning electron microscopy; X-ray dispersive analysis; infrared spectroscopy; X-ray diffraction and mechanical tests of hardness, elasticity and deformation. With scanning electron microscopy, the morphology of the Pla surface unirradiated was observed, in which an apparently smooth surface was observed, after changes that had the Pla when irradiated also was observed, where the effects of radiation were observed in form of scratch, agglomeration and small fractures. By X-ray dispersive analysis was determined and verified the elemental chemical composition of the Pla; as expected the tests showed only carbon, oxygen and hydrogen. With thermo-gravimetric/Mass analysis the decomposition temperatures of Pla were determined, identifying that the degradation compounds are CO, CO 2 and CH 4 . With infrared spectrometry the major peaks of Pla were observed before and after being irradiated with increasing of radiation dose the intensity of the bands decreased. Also by X-ray diffraction was observed that the polymer is an amorphous material. The mechanical tests indicate that the values of each of the tests decrease significantly with increasing the radiation dose. (Author)

Determination of acetylsalicylic acid and salicylic acid in foods, using HPLC with fluorescence detection.

NARCIS (Netherlands)

Venema, D.P.; Hollman, P.C.H.; Janssen, P.L.T.M.K.; Katan, M.B.

1996-01-01

We developed a specific and sensitive HPLC method with fluorescence detection for the determination of free acetylsalicylic acid, free salicylic acid, and free salicylic acid plus salicylic acid after alkaline hydrolysis (free-plus-bound) in foods. Acetylsalicylic acid was detected after postcolumn

An extremely sensitive monoboronic acid based fluorescent sensor for glucose

International Nuclear Information System (INIS)

Sun Xiangying; Liu Bin; Jiang Yunbao

2004-01-01

An extremely sensitive monoboronic acid based fluorescent sensor for glucose was developed. This was carried out by assembling a fluorescent monoboronic acid, 3-aminophenylboronic acid (PBA) indirectly onto gold surface via its electrostatic interaction with cysteine (Cys) that was directly assembled on the gold surface. The formation of self-assembled bilayers (SAB) was confirmed and primarily characterized by cyclic voltammetry and X-ray photoelectron spectra (XPS). The SAB containing PBA was found fluorescent and its fluorescence showed an extremely high sensitivity to the presence of glucose and other monosaccharides such as galactose and fructose with quenching constants at 10 8 M -1 order of magnitude compared to those at 10 2 M -1 in bulk solutions. The quenching constants were found to vary in the order of D-glucose>D-galactose>D-fructose>D-mannose that is different from that in bulk solution which shows the highest binding affinity toward D-fructose and very low sensitivity toward glucose. The reported monoboronic acid based SAB fluorescent sensor showed the highest sensitivity towards glucose with the capacity of detecting saccharides of concentration down to nanomolar level. It was also demonstrated that the fluorescence from PBA/Cys/Au can be easily recovered after each measurement event and therefore also represents a new reusable method for immobilizing reagent in fabricating chemosensors

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.

A new fluorescent pH probe for extremely acidic conditions

Energy Technology Data Exchange (ETDEWEB)

Xu, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Jiang, Zheng [School of Life Science, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Xiao, Yu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Bi, Fu-Zhen [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

2014-04-01

A new coumarin-based fluorescent probe can detect highly acidic conditions in both solution and bacteria with high selectivity and sensitivity. Highlights: • A new fluorescence probe for very low pH was synthesized and characterized. • The probe can monitor pH in solution and bacteria. • The two-step protonation of N atoms of the probe leads to fluorescence quenching. Abstract: A novel turn-off fluorescent probe based on coumarin and imidazole moiety for extremely acidic conditions was designed and developed. The probe with pK_a = 2.1 is able to respond to very low pH value (below 3.5) with high sensitivity relying on fluorescence quenching at 460 nm in fluorescence spectra or the ratios of absorbance maximum at 380 nm to that at 450 nm in UV–vis spectra. It can quantitatively detect pH value based on equilibrium equation, pH = pK_a -log[(I_x - I_b)/(I_a - I_x)]. It had very short response time that was less than 1 min, good reversibility and nearly no interference from common metal ions. Moreover, using ¹H NMR analysis and theoretical calculation of molecular orbital, we verified that a two-step protonation process of two N atoms of the probe leaded to photoinduced electron transfer (PET), which was actually the mechanism of the fluorescence quenching phenomenon under strongly acidic conditions. Furthermore, the probe was also applied to imaging strong acidity in bacteria, E.coli and had good effect. This work illustrates that the new probe could be a practical and ideal pH indicator for strongly acidic conditions with good biological significance.

Performance properties, lactic acid specific migration and swelling by simulant of biodegradable poly(lactic acid)/nanoclay multilayer films for food packaging.

Science.gov (United States)

Scarfato, Paola; Di Maio, Luciano; Milana, Maria Rosaria; Giamberardini, Silvia; Denaro, Massimo; Incarnato, Loredana

2017-10-01

The aim of the study was the development of a multifunctional, high-performance, fully biodegradable multilayer polylactic acid (PLA) film for food packaging applications. In particular, sealable multilayer PLA-clay nanocomposite systems with different layouts in terms of composition and relative thickness of the layers, all consisting of a PLA-clay nanocomposite layer between two pure PLA layers for direct food contact, were designed and produced by blown film co-extrusion. The films obtained were analysed for their morphology, functional properties and lactic acid (LA)-specific migration in 50% ethanol. The results showed that, with respect to the unfilled multilayer system, taken as a reference, the nanocomposite films had significant improvements, up to about 40%, in their barriers to oxygen and tensile strengths, and resulted in being more easily sealable over a wide heat-sealing temperature range (80-100°C) with higher seal strength. Moreover, all films had LA migrations always well below the former generic overall migration limit of 60 mg kg -1 food (10 mg dm - 2 ) of European Union Regulation No. 10/2011 (deleted by the amending Regulation No. 2016/1416), even if their morphology was strongly modified during the migration tests due to the strong swelling action of the used simulant (simulant D1 = 50% ethanol (aq.) (v/v)) towards PLA.

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.

Effect of thermoplastic polyurethane (TPU) on the thermal and mechanical properties of polylactic acid (PLA)/curcumin blends

Science.gov (United States)

Sharifah, I. S. S.; Adnan, M. D. A.; Nor Khairusshima, M. K.; Shaffiar, N. M.; Buys, Y. F.

2018-01-01

Polylactic acid (PLA) is known to be brittle by nature and thus limits the flexibility of the polymer. A possible solution to enhance the flexibility of PLA is to add a flexible polymeric based material such as thermoplastic polyurethane (TPU). In this study, 30-50 wt% of TPU was added into PLA/curcumin blends to improve its flexibility. Thermal analysis using differential scanning calorimetry shows that further additions of TPU at the expense of PLA did not affect the glass transition temperature, crystallisation temperature and melting temperature of the blends. Fibers of PLA/curcumin/TPU were successfully drawn and Single Fiber Tensile Test (SFTT) showed vast improvement in elongation at break. The initial addition of 30 wt% of TPU to the brittle PLA/curcumin composition causes a significant increase in elongation at break by 39 times and further additions at 50 wt %, the elongation at break increases by 105 times. However, with the increase in elongation, a decrease in strength and Young’s modulus was observed.

A stimuli-responsive fluorescence platform for simultaneous determination of D-isoascorbic acid and Tartaric acid based on Maillard reaction product

Science.gov (United States)

Zhao, Yanmei; Yuan, Haiyan; Zhang, Xinling; Yang, Jidong

2018-05-01

An activatable fluorescence monitoring platform based on a novel Maillard reaction product from D-glucose and L-arginine was prepared through a facile one-pot approach and applied for simultaneous detection of D-isoascorbic acid and tartaric acid. In this work, the new Maillard reaction product GLA was first obtained, and its fluorescence intensity can be effectively quenched by KMnO4, resulting from a new complex (GLA-KMnO4) formation between GLA and KMnO4. Upon addition of D-isoascorbic acid or tartaric acid, an enhanced fluorescence was observed under the optimumed experimental conditions, indicating a stimuli-responsive fluorescence turn on platform for D-isoascorbic acid or tartaric acid can be developed. The corresponding experimental results showed that this turn on fluorescence sensing platform has a high sensitivity for D-isoascorbic acid or tartaric acid, because the detection limits were 5.9 μM and 21.5 μM, respectively. Additionally, this proposed sensing platform was applied to simultaneously detection of D-isoascorbic acid and tartaric acid in real tap water samples with satisfactory results.

Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

International Nuclear Information System (INIS)

Makarska-Bialokoz, Magdalena; Borowski, Piotr

2015-01-01

The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H 2 TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10 5 mol −1 . The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H 2 TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated

Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

Energy Technology Data Exchange (ETDEWEB)

Makarska-Bialokoz, Magdalena, E-mail: makarska@hektor.umcs.lublin.pl [Department of Inorganic Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 2, 20-031 Lublin (Poland); Borowski, Piotr [Faculty of Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 3, 20-031 Lublin (Poland)

2015-04-15

The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H{sub 2}TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10{sup 5} mol{sup −1}. The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H{sub 2}TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated.

Boronic acids for fluorescence imaging of carbohydrates.

Science.gov (United States)

Sun, Xiaolong; Zhai, Wenlei; Fossey, John S; James, Tony D

2016-02-28

"Fluorescence imaging" is a particularly exciting and rapidly developing area of research; the annual number of publications in the area has increased ten-fold over the last decade. The rapid increase of interest in fluorescence imaging will necessitate the development of an increasing number of molecular receptors and binding agents in order to meet the demand in this rapidly expanding area. Carbohydrate biomarkers are particularly important targets for fluorescence imaging given their pivotal role in numerous important biological events, including the development and progression of many diseases. Therefore, the development of new fluorescent receptors and binding agents for carbohydrates is and will be increasing in demand. This review highlights the development of fluorescence imaging agents based on boronic acids a particularly promising class of receptors given their strong and selective binding with carbohydrates in aqueous media.

Fabrication of polylactic acid/hydroxyapatite/graphene oxide composite and their thermal stability, hydrophobic and mechanical properties

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Ming Gong

2017-06-01

Full Text Available A series of polylactic acid/hydroxyapatite/graphene oxide composite (PLA/HA/GO were fabricated via solution blending and casting method using N,N-dimethyl-formamide (DMF and CH2Cl2 as mutual solvents. The physicochemical properties of the resulting composites were characterized by means of FT-IR, SEM, TEM, Raman spectra, XRD and N2-physisorption. Particularly, the thermal stabilities, hydrophobic and mechanical properties of PLA/HA/GO composites were systematically investigated. The influences of GO content on thermal stabilities, hydrophobic and mechanical properties of the composites were also evaluated. The results showed that the addition of GO and HA not only improved the thermal stability of PLA, but also improved the hydrophobic property of PLA-based composites. By compared with the PLA/HA/GO composite, the tensile strength of pristine PLA is slight high. The tensile strength and hardness of PLA/HA/GO composites increased with the increase of GO content. The obtained PLA/HA/GO composite may be a promising material for load-bearing orthopedic implants.

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

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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.

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

Effect of Filler Content and Chemical Modification on Mechanical Properties of Polylactic Acid/Polymethyl Methacrylate/Nypa Fruticans Husk Biocomposites

Science.gov (United States)

Mohamad Syahmie, MR; Pei Leng, T.; Nurul Najwa, Zabidi

2018-03-01

The main purpose of incorporating Nypa fruticans husks (NFH) into Polylactic acid (PLA)/Polymethylmethacrylate (PMMA) is to decrease the costs and enhanced the properties of the biocomposites. 3-Aminopropyl Triethoxysilane (3-APE) was used as coupling agent. The effect of NFH content and 3-APE on the mechanical properties and morphology of the biocomposites were investigated. Results show that the effect of NFH content increased Young’s modulus but decreased the tensile strength and elongation at break of PLA/PMMA/NFH biocomposites. However, silanized biocomposites using 3-APE) was found to enhanced the tensile strength and Young’s modulus but decreased the elongation at break of the silanized biocomposites. Scanning electron microscopy (SEM) study of the tensile fracture surface of the biocomposites indicated that the used of 3-APE as couling agent improved the interfacial interaction netween NFH and PLA/PMMA blends.

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

Science.gov (United States)

Gartner, Hunter; Li, Yana; Almenar, Eva

2015-03-01

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

Characterization of hydrolytic degradation of polylactic acid/rice hulls composites in water at different temperatures

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2011-02-01

Full Text Available Hydrolytic degradations of polylactic acid/rice hulls (PLA/RH composites with various rice hulls contents due to water absorptions at 23, 51 and 69°C were investigated by studying the thermal properties, chemical composition, molecular weight, and morphology of the degraded products. The results have attested that the stability of PLA/RH composites in water depends slightly on rice hulls contents but it is significantly influenced by water temperature. Water absorption in 30 days at 23°C was between 0.87 and 9.25% depending on rice hull contents. However, at thermophilic temperatures, the water absorption and degradation of these products were increased significantly. Saturations were achieved in less than 25 and 9 days at 51°C and 69°C, respectively, while hydrolytic degradation was demonstrated by an increase in fragility and development of crystallinity. At 69°C, there were significant reductions of the decomposition and glass transition temperatures of the polymer by 13°C. These changes were associated with the reduction of the molecular weight of PLA from 153.1 kDa to ~10.7 kDa due to hydrolysis of its ester group.

Aligned flax fibre/polylactate composites

DEFF Research Database (Denmark)

Madsen, Bo; Lilholt, Hans; Thygesen, Anders

2008-01-01

The potential of biocomposites in engineering applications is demonstrated by using aligned flax fibre/polylactate composites as a materials model system. The failure stress of flax fibres is measured by tensile testing of single fibres and fibre bundles. For both fibre configurations, it is found...... that failure stress is decreased by increasing the tested fibre volume. Based on two types of flax fibre preforms: carded sliver and unidirectional non-crimp fabric, aligned flax fibre/polylactate composites were fabricated with variable fibre content. The volumetric composition and tensile properties...... of the composite were measured. For composites with a fibre content of 37 % by volume, stiffness is about 20 GPa and failure stress is about 180 MPa. The tensile properties of the composites are analysed with a modified rule of mixtures model, which includes the effect of porosity. The experimental results...

A stimuli-responsive fluorescence platform for simultaneous determination of d-isoascorbic acid and Tartaric acid based on Maillard reaction product.

Science.gov (United States)

Zhao, Yanmei; Yuan, Haiyan; Zhang, Xinling; Yang, Jidong

2018-05-05

An activatable fluorescence monitoring platform based on a novel Maillard reaction product from d-glucose and L-arginine was prepared through a facile one-pot approach and applied for simultaneous detection of d-isoascorbic acid and tartaric acid. In this work, the new Maillard reaction product GLA was first obtained, and its fluorescence intensity can be effectively quenched by KMnO 4 , resulting from a new complex (GLA-KMnO 4 ) formation between GLA and KMnO 4 . Upon addition of d-isoascorbic acid or tartaric acid, an enhanced fluorescence was observed under the optimumed experimental conditions, indicating a stimuli-responsive fluorescence turn on platform for d-isoascorbic acid or tartaric acid can be developed. The corresponding experimental results showed that this turn on fluorescence sensing platform has a high sensitivity for d-isoascorbic acid or tartaric acid, because the detection limits were 5.9μM and 21.5μM, respectively. Additionally, this proposed sensing platform was applied to simultaneously detection of d-isoascorbic acid and tartaric acid in real tap water samples with satisfactory results. Copyright © 2018 Elsevier B.V. All rights reserved.

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

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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.

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

Science.gov (United States)

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

2015-12-15

This paper discusses application of Carbon Footprint (CF) for quantification of the 100-year Global Warming Potential (GWP100) associated with the life cycle of polylactic acid (PLA) trays for packaging of fresh foods. A comparison with polystyrene (PS)-based trays was done considering two different transport system scenarios for PLA-granule supply to the tray production firm: a transoceanic freight vessel and an intercontinental freight aircraft. Doing so enabled estimation of the influence of the transportation phase on the GHG-emission rate associated with the PLA-trays' life cycle. From the assessment, the GWP100 resulted to be mainly due to PLA-granulate production and to its transportation to the tray manufacturing facility. Also, the study documented that, depending upon the transport system considered, the CF associated with the life cycle of the PLA trays can worsen so much that the latter are no longer GHG-emission saving as they are expected to be compared to the PS ones. Therefore, based upon the findings of the study, it was possible for the authors to understand the importance and the need of accounting for the transport-related issues in the design of PLA-based products, thus preserving their environmental soundness compared to traditional petroleum-based products. In this context, the study could be used as the base to reconsider the merits of PLA usage for product manufacturing, especially when high distances are implied, as in this analysed case. So, the authors believe that new research and policy frameworks should be designed and implemented for both development and promotion of more globally sustainable options. Copyright © 2015 Elsevier B.V. All rights reserved.

Investigating the use of coupling agents to improve the interfacial properties between a resorbable phosphate glass and polylactic acid matrix.

Science.gov (United States)

Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew J; Rudd, Chris D; Walker, Gavin S; Scotchford, Colin A

2013-09-01

Eight different chemicals were investigated as potential candidate coupling agents for phosphate glass fibre reinforced polylactic acid composites. Evidence of reaction of the coupling agents with phosphate glass and their effect on surface wettability and glass degradation were studied along with their principle role of improving the interface between glass reinforcement and polymer matrix. It was found that, with an optimal amount of coupling agent on the surface of the glass/polymer, interfacial shear strength improved by a factor of 5. Evidence of covalent bonding between agent and glass was found for three of the coupling agents investigated, namely: 3-aminopropyltriethoxysilane; etidronic acid and hexamethylene diisocyanate. These three coupling agents also improved the interfacial shear strength and increased the hydrophobicity of the glass surface. It is expected that this would provide an improvement in the macroscopic properties of full-scale composites fabricated from the same materials which may also help to retain these properties for the desired length of time by retarding the breakdown of the fibre/matrix interface within these composites.

Preparation of Rhodamine B Fluorescent Poly(methacrylic acid) Coated Gelatin Nanoparticles

OpenAIRE

Gan, Zhenhai; Ju, Jianhui; Zhang, Ting; Wu, Daocheng

2011-01-01

Poly(methacrylic acid) (PMAA)-coated gelatin nanoparticles encapsulated with fluorescent dye rhodamine B were prepared by the coacervation method with the aim to retard the release of rhodamine B from the gelatin matrix. With sodium sulfate as coacervation reagent for gelatin, a kind of biopolymer with excellent biocompatibility, the formed gelatin nanoparticles were cross-linked by formaldehyde followed by the polymerization of methacrylic acid coating. The fluorescent poly(methacrylic acid)...

Enantioselective recognition of mandelic acid by a 3,6-dithiophen-2-yl-9H-carbazole-based chiral fluorescent bisboronic acid sensor.

Science.gov (United States)

Wu, Yubo; Guo, Huimin; James, Tony D; Zhao, Jianzhang

2011-07-15

We have prepared chiral fluorescent bisboronic acid sensors with 3,6-dithiophen-2-yl-9H-carbazole as the fluorophore. The thiophene moiety was used to extend the π-conjugation framework of the fluorophore in order to red-shift the fluorescence emission and, at the same time, to enhance the novel process where the fluorophore serves as the electron donor of the photoinduced electron transfer process (d-PET) of the boronic acid sensors; i.e., the background fluorescence of the sensor 1 at acidic pH is weaker compared to that at neutral or basic pH, in stark contrast to the typical a-PET boronic acid sensors (where the fluorophore serves as the electron acceptor of the photoinduced electron transfer process). The benefit of the d-PET boronic acid sensors is that the recognition of the hydroxylic acids can be achieved at acidic pH. We found that the thiophene moiety is an efficient π-conjugation linker and electron donor; as a result, the d-PET contrast ratio of the sensors upon variation of the pH is improved 10-fold when compared to the previously reported d-PET sensors without the thiophene moiety. Enantioselective recognition of tartaric acid was achieved at acid pH, and the enantioselectivity (total response K(D)I(F)(D)/K(L)I(F)(L)) is 3.3. The fluorescence enhancement (I(F)(Sample)/I(F)(Blank)) of sensor 1 upon binding with tartaric acid is 3.5-fold at pH 3.0. With the fluorescent bisboronic acid sensor 1, enantioselective recognition of mandelic acid was achieved for the first time. To the best of our knowledge, this is the first time that the mandelic acid has been enantioselectively recognized using a chiral fluorescent boronic acid sensor. Chiral monoboronic acid sensor 2 and bisboronic acid sensor 3 without the thiophene moiety failed to enantioselectively recognize mandelic acid. Our findings with the thiophene-incorporated boronic acid sensors will be important for the design of d-PET fluorescent sensors for the enantioselective recognition of �

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.

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.

Fluorescent Proteins for Investigating Biological Events in Acidic Environments

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Hajime Shinoda

2018-05-01

Full Text Available The interior lumen of acidic organelles (e.g., endosomes, secretory granules, lysosomes and plant vacuoles is an important platform for modification, transport and degradation of biomolecules as well as signal transduction, which remains challenging to investigate using conventional fluorescent proteins (FPs. Due to the highly acidic luminal environment (pH ~ 4.5–6.0, most FPs and related sensors are apt to lose their fluorescence. To address the need to image in acidic environments, several research groups have developed acid-tolerant FPs in a wide color range. Furthermore, the engineering of pH insensitive sensors, and their concomitant use with pH sensitive sensors for the purpose of pH-calibration has enabled characterization of the role of luminal ions. In this short review, we summarize the recent development of acid-tolerant FPs and related functional sensors and discuss the future prospects for this field.

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

Effect of dielectric barrier discharge treatment on surface nanostructure and wettability of polylactic acid (PLA) nonwoven fabrics

Science.gov (United States)

Ren, Yu; Xu, Lin; Wang, Chunxia; Wang, Xiaona; Ding, Zhirong; Chen, Yuyue

2017-12-01

Polylactic acid (PLA) nonwoven fabrics are treated with atmospheric dielectric barrier discharge (DBD) plasma to improve surface wettability. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that micro- to nano-scale textures appear on the treated PLA surfaces dependent on the treatment time. X-ray photoelectron spectroscopy (XPS) analysis reveals that the DBD plasma treatments result in decreased carbon contents and increased oxygen contents as well as slightly increased nitrogen contents. The water contact angle decreases sharply with the increase of the DBD plasma treatment time. The super hydrophilic PLA surfaces (the water contact angle reached 0°) are obtained when the treatment time is longer than 90 s. Ninety days after the DBD plasma treatment, the XPS analysis shows that Csbnd O/Csbnd N and Cdbnd O/Osbnd Cdbnd O percentages decline for all treatment groups. However, the water contact angle is kept constant at 0° for the groups treated above 90 s, which could be due to the oxidized nano-structured layer on the DBD plasma treated PLA surfaces.

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.

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

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Daniela Sánchez Aldana

2014-09-01

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

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

Directory of Open Access Journals (Sweden)

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

Preparation of Rhodamine B Fluorescent Poly(methacrylic acid Coated Gelatin Nanoparticles

Directory of Open Access Journals (Sweden)

Zhenhai Gan

2011-01-01

Full Text Available Poly(methacrylic acid (PMAA-coated gelatin nanoparticles encapsulated with fluorescent dye rhodamine B were prepared by the coacervation method with the aim to retard the release of rhodamine B from the gelatin matrix. With sodium sulfate as coacervation reagent for gelatin, a kind of biopolymer with excellent biocompatibility, the formed gelatin nanoparticles were cross-linked by formaldehyde followed by the polymerization of methacrylic acid coating. The fluorescent poly(methacrylic acid coated gelatin (FPMAAG nanoparticles had a uniform spherical shape and a size distribution of 60±5 nm. Infrared spectral analysis confirmed the formation of PMAA coating on the gelatin nanoparticles. Based on UV-Vis spectra, the loading efficiency of rhodamine B for the FPMAAG nanoparticles was 0.26 μg per mg nanoparticles. The encapsulated rhodamine B could sustain for two weeks. Favorable fluorescence property and fluorescence imaging of cells confirmed that the FPMAAG nanoparticles have promising biochemical, bioanalytical, and biomedical applications.

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.

Supercritical impregnation of cinnamaldehyde into polylactic acid as a route to develop antibacterial food packaging materials.

Science.gov (United States)

Villegas, Carolina; Torres, Alejandra; Rios, Mauricio; Rojas, Adrián; Romero, Julio; de Dicastillo, Carol López; Valenzuela, Ximena; Galotto, María José; Guarda, Abel

2017-09-01

Supercritical impregnation was used to incorporate a natural compound with antibacterial activity into biopolymer-based films to develop active food packaging materials. Impregnation tests were carried out under two pressure conditions (9 and 12MPa), and three depressurization rates (0.1, 1 and 10MPamin -1 ) in a high-pressure cell at a constant temperature equal to 40°C. Cinnamaldehyde (Ci), a natural compound with proven antimicrobial activity, was successfully incorporated into poly(lactic acid) films (PLA) using supercritical carbon dioxide (scCO 2 ), with impregnation yields ranging from 8 to 13% w/w. Higher pressure and slower depressurization rate seem to favor the Ci impregnation. The incorporation of Ci improved thermal, structural and mechanical properties of the PLA films. Impregnated films were more flexible, less brittle and more resistant materials than neat PLA films. The tested samples showed strong antibacterial activity against the selected microorganisms. In summary, this study provides an innovative route to the development of antibacterial biodegradable materials, which could be used in a wide range of applications of active food packaging. Copyright © 2017 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.

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.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

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); Collaborative Innovation Center of Textile and Garment Industry, Henan Province, 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); Collaborative Innovation Center of Textile and Garment Industry, Henan Province, Zhengzhou 450007 (China); Han, Qiming [Henan provincial key laboratory of functional textile materials, Zhongyuan University of Technology, Zhengzhou 450007 (China); Collaborative Innovation Center of Textile and Garment Industry, Henan Province, 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); Collaborative Innovation Center of Textile and Garment Industry, Henan Province, 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); Collaborative Innovation Center of Textile and Garment Industry, Henan Province, Zhengzhou 450007 (China); and others

2016-10-01

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

Impact of the Fused Deposition (FDM Printing Process on Polylactic Acid (PLA Chemistry and Structure

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Michael Arthur Cuiffo

2017-06-01

Full Text Available Polylactic acid (PLA is an organic polymer commonly used in fused deposition (FDM printing and biomedical scaffolding that is biocompatible and immunologically inert. However, variations in source material quality and chemistry make it necessary to characterize the filament and determine potential changes in chemistry occurring as a result of the FDM process. We used several spectroscopic techniques, including laser confocal microscopy, Fourier transform infrared (FTIR spectroscopy and photoacousitc FTIR spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS in order to characterize both the bulk and surface chemistry of the source material and printed samples. Scanning electron microscopy (SEM and differential scanning calorimetry (DSC were used to characterize morphology, cold crystallinity, and the glass transition and melting temperatures following printing. Analysis revealed calcium carbonate-based additives which were reacted with organic ligands and potentially trace metal impurities, both before and following printing. These additives became concentrated in voids in the printed structure. This finding is important for biomedical applications as carbonate will impact subsequent cell growth on printed tissue scaffolds. Results of chemical analysis also provided evidence of the hygroscopic nature of the source material and oxidation of the printed surface, and SEM imaging revealed micro- and submicron-scale roughness that will also impact potential applications.

A novel acidic pH fluorescent probe based on a benzothiazole derivative

Science.gov (United States)

Ma, Qiujuan; Li, Xian; Feng, Suxiang; Liang, Beibei; Zhou, Tiqiang; Xu, Min; Ma, Zhuoyi

2017-04-01

A novel acidic pH fluorescent probe 1 based on a benzothiazole derivative has been designed, synthesized and developed. The linear response range covers the acidic pH range from 3.44 to 6.46, which is valuable for pH researches in acidic environment. The evaluated pKa value of the probe 1 is 4.23. The fluorescence enhancement of the studied probe 1 with an increase in hydrogen ions concentration is based on the hindering of enhanced photo-induced electron transfer (PET) process. Moreover, the pH sensor possesses a highly selective response to H+ in the presence of metal ions, anions and other bioactive small molecules which would be interfere with its fluorescent pH response. Furthermore, the probe 1 responds to acidic pH with short response time that was less than 1 min. The probe 1 has been successfully applied to confocal fluorescence imaging in live HeLa cells and can selectively stain lysosomes. All of such good properties prove it can be used to monitoring pH fluctuations in acidic environment with high sensitivity, pH dependence and short response time.

Co-Deposition of a Hydrogel/Calcium Phosphate Hybrid Layer on 3D Printed Poly(Lactic Acid Scaffolds via Dip Coating: Towards Automated Biomaterials Fabrication

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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.

Comparative effectiveness of using resorbable membranes of polylactic acid and collagen in regeneration of bone defects in patients with periimplantitis

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Gudaryan A.A.

2014-03-01

Full Text Available The article presents the results of comparative study of effectiveness of usage of separation membranes from polylactic acid (PLA and collagen in carrying out targeted regeneration of bone tissue in 22 patients with periimplantitis. Purpose: To conduct a comparative clinico-radiological efficiency of PLA membrane and collagen membranes in removing bone defects of the alveolar bone in patients with periimplantitis in clinic. It was found that depending on the type of membrane, bone tissue growth occurs not in the same way. Surgery in treatment of periimplantitis using osteo-inducing agent «Bio-Oss» and PLA membranes allows to reach full recovery of bone in bone defects in 90.9 % of patients versus 63.63 % of cases with collagen membranes. Thus, reconstitution of bone in bone defects in periimplantitis is more of full value in using PLA membranes than with membranes from collagen.

Fluorescence properties of Schiff base - N,N‧-bis(salicylidene) - 1,2-Phenylenediamine in presence of bile acid host

Science.gov (United States)

Roy, Nayan; Paul, Pradip C.; Singh, T. Sanjoy

2015-05-01

Fluorescence properties of Schiff base - N,N‧-bis(salicylidene) - 1,2-phenylenediamine (LH2) is used to study the micelles formed by aggregation of different important bile acids like cholic acid, deoxycholic acid, chenodeoxycholic acid and glycocholic acid by steady state and picosecond time-resolved fluorescence spectroscopy. The fluorescence band intensity was found out to increase with concomitant red shift with gradual addition of different bile acids. Binding constant of the probe with different bile acids as well as critical micelle concentration was obtained from the variation of fluorescence intensity on increasing concentration of bile acids in the medium. The increase in fluorescence quantum yields, fluorescence decay times and substantial decrease in nonradiative decay rate constants in bile acids micellar environment points to the restricted motion of the fluorophore inside the micellar subdomains.

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...

Recent Advances in Fluorescent Arylboronic Acids for Glucose Sensing

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Jon Stefan Hansen

2013-12-01

Full Text Available Continuous glucose monitoring (CGM is crucial in order to avoid complications caused by change in blood glucose for patients suffering from diabetes mellitus. The long-term consequences of high blood glucose levels include damage to the heart, eyes, kidneys, nerves and other organs, among others, caused by malign glycation of vital protein structures. Fluorescent monitors based on arylboronic acids are promising candidates for optical CGM, since arylboronic acids are capable of forming arylboronate esters with 1,2-cis-diols or 1,3-diols fast and reversibly, even in aqueous solution. These properties enable arylboronic acid dyes to provide immediate information of glucose concentrations. Thus, the replacement of the commonly applied semi-invasive and non-invasive techniques relying on glucose binding proteins, such as concanavalin A, or enzymes, such as glucose oxidase, glucose dehydrogenase and hexokinases/glucokinases, might be possible. The recent progress in the development of fluorescent arylboronic acid dyes will be emphasized in this review.

Direct solid surface fluorescence spectroscopy of standard chemicals and humic acid in ternary system.

Science.gov (United States)

Mounier, S; Nicolodelli, G; Redon, R; Milori, D M B P

2017-04-15

The front face fluorescence spectroscopy is often used to quantify chemicals in well-known matrices as it is a rapid and powerful technique, with no sample preparation. However it was not used to investigate extracted organic matter like humic substances. This work aims to fully investigate for the first time front face fluorescence spectroscopy response of a ternary system including boric acid, tryptophan and humic substances, and two binaries system containing quinine sulfate or humic substance in boric acid. Pure chemicals, boric acid, tryptophan, quinine sulfate and humic acid were mixed together in solid pellet at different contents from 0 to 100% in mass. The measurement of excitation emission matrix of fluorescence (3D fluorescence) and laser induced fluorescence were then done in the front face mode. Fluorescence matrices were decomposed using the CP/PARAFAC tools after scattering treatments. Results show that for 3D fluorescence there is no specific component for tryptophan and quinine sulfate, and that humic substances lead to a strong extinction effect for mixture containing quinine sulfate. Laser induced fluorescence gives a very good but non-specific related response for both quinine sulfate and tryptophan. No humic substances fluorescence response was found, but extinction effect is observed as for 3D fluorescence. This effect is stronger for quinine sulfate than for tryptophan. These responses were modeled using a simple absorbance versus emission model. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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

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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.

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.

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.

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.

Effectiveness of trimethylopropane trimethacrylate for the electron-beam-irradiation-induced cross-linking of polylactic acid

Energy Technology Data Exchange (ETDEWEB)

Ng, Hon-Meng [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Bee, Soo-Tueen, E-mail: beest@utar.edu.my [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Ratnam, C.T. [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Sin, Lee Tin; Phang, Yee-Yao; Tee, Tiam-Ting [Department of Chemical Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, 53300 Setapak, Kuala Lumpur (Malaysia); Rahmat, A.R. [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

2014-01-15

Highlights: • Investigation of trimethylopropane trimethacrylate (TMPTMA) on electron beam irradiated PLA. • Irradiated PLA blends were weakened by incorporation of high amount of TMPTMA. • TMPTMA interacts with polymer free radicals to build crosslinking network. -- Abstract: The purpose of this research was to investigate the effects of various loading levels of trimethylopropane trimethacrylate (TMPTMA) on the properties of polylactic acid (PLA) cross-linked via electron-beam irradiation. PLA was compounded with 3–5 wt.% of TMPTMA to induce cross-linking upon subjection to electron-beam irradiation doses of 25–250 kGy. The physical properties of the PLA samples were characterised by means of X-ray diffraction, gel fraction and scanning electron microscopy analyses on fractured surfaces after tensile tests. The presence of TMPTMA in PLA was found to effectively increase the crystallite size and gel fraction. However, higher loading levels of TMPTMA could compromise the properties of the PLA/TMPTMA samples, indicating that a larger amount of monomer free radicals might promote degradation within the substantially cross-linked amorphous phase. Irradiation-induced cross-linking in the samples could improve the cross-linking density while decreasing the elongation and interfering with the crystallisation. These effects are caused by the intensive irradiation-induced chain scission that is responsible for the deterioration of the mechanical and crystalline properties of the samples.

Biodegradation behaviors and color change of composites based on type of bagasse pulp/polylactic acid

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maryam allahdadi

2017-05-01

Full Text Available In this research, appearance quality and decay resistance of polylactic acid (PLA based green composites made from monoethanolamine (MEA bagasse pulp, alkaline sulfite-anthraquinone (AS bagasse pulp, bleached soda (B S bagasse pulp, unbleached soda (UN S bagasse pulp (UN S bagasse pulp and raw bagasse fibers (B were investigated. For the investigation of biodegradation behaviors, effect of the white rot fungi (Coriolus versicolor on the neat PLA and composites with natural fibers during 30 and 60 days were studied. It is found that when the bagasse fibers were incorporated into composites matrix, percentage weight reduction and stiffness of samples have been increased. Also, the rate of loss mentioned of the composites made from bagasse pulp fibers were superior to the relevant raw bagase fibers. This can be explained by the removal of non-cellulosic components such as lignin and hemicelluloses from the fibers by pulping process. Also, the results indicates the inferior of surface qualities of fabricated composites regarding to neat PLA. Depending on the fiber type, different reductions of the surface qualities were attained. However, the degree of color change of the composites with any type of bagasse pulp fibers were lower compared with composite with raw bagasse fiber. Finally, as compared with the raw bagasse fibers, bagasse pulp fibers have better reinforcing capability.

Effectiveness of trimethylopropane trimethacrylate for the electron-beam-irradiation-induced cross-linking of polylactic acid

International Nuclear Information System (INIS)

Ng, Hon-Meng; Bee, Soo-Tueen; Ratnam, C.T.; Sin, Lee Tin; Phang, Yee-Yao; Tee, Tiam-Ting; Rahmat, A.R.

2014-01-01

Highlights: • Investigation of trimethylopropane trimethacrylate (TMPTMA) on electron beam irradiated PLA. • Irradiated PLA blends were weakened by incorporation of high amount of TMPTMA. • TMPTMA interacts with polymer free radicals to build crosslinking network. -- Abstract: The purpose of this research was to investigate the effects of various loading levels of trimethylopropane trimethacrylate (TMPTMA) on the properties of polylactic acid (PLA) cross-linked via electron-beam irradiation. PLA was compounded with 3–5 wt.% of TMPTMA to induce cross-linking upon subjection to electron-beam irradiation doses of 25–250 kGy. The physical properties of the PLA samples were characterised by means of X-ray diffraction, gel fraction and scanning electron microscopy analyses on fractured surfaces after tensile tests. The presence of TMPTMA in PLA was found to effectively increase the crystallite size and gel fraction. However, higher loading levels of TMPTMA could compromise the properties of the PLA/TMPTMA samples, indicating that a larger amount of monomer free radicals might promote degradation within the substantially cross-linked amorphous phase. Irradiation-induced cross-linking in the samples could improve the cross-linking density while decreasing the elongation and interfering with the crystallisation. These effects are caused by the intensive irradiation-induced chain scission that is responsible for the deterioration of the mechanical and crystalline properties of the samples

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

Science.gov (United States)

Jin, T; Zhang, H

2008-04-01

Biodegradable polylactic acid (PLA) polymer was evaluated for its application as a material for antimicrobial food packaging. PLA films were incorporated with nisin to for control of foodborne pathogens. Antimicrobial activity of PLA/nisin films against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis were evaluated in culture media and liquid foods (orange juice and liquid egg white). Scanned electron micrograph and confocal laser microscopy revealed that nisin particles were evenly distributed in PLA polymer matrix on the surface and inside of the PLA/nisin films. PLA/nisin significantly inhibited growth of L. monocytogenes in culture medium and liquid egg white. The greatest inhibition occurred at 24 h when the cell counts of L. monocytogenes in the PLA/nisin samples were 4.5 log CFU/mL less than the controls. PLA/nisin reduced the cell population of E. coli O157:H7 in orange juice from 7.5 to 3.5 log at 72 h whereas the control remained at about 6 log CFU/mL. PLA/nisin treatment resulted in a 2 log reduction of S. Enteritidis in liquid egg white at 24 degrees C. After 21 d at 4 degrees C the S. Enteritidis population from PLA/nisin treated liquid egg white (3.5 log CFU/mL) was significantly less than the control (6.8 log CFU/mL). E. coli O157:H7 in orange juice was more sensitive to PLA/nisin treatments than in culture medium. The results of this research demonstrated the retention of nisin activity when incorporated into the PLA polymer and its antimicrobial effectiveness against foodborne pathogens. The combination of a biopolymer and natural bacteriocin has potential for use in antimicrobial food packaging.

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

Three-dimensional fluorescence analysis of chernozem humic acids and their electrophoretic fractions

Science.gov (United States)

Trubetskoi, O. A.; Trubetskaya, O. E.

2017-09-01

Polyacrylamide gel electrophoresis in combination with size-exclusion chromatography (SEC-PAGE) has been used to obtain stable electrophoretic fractions of different molecular size (MS) from chernozem humic acids (HAs). Three-dimensional fluorescence charts of chernozem HAs and their fractions have been obtained for the first time, and all fluorescence excitation-emission maxima have been identified in the excitation wavelength range of 250-500 nm. It has been found that fractionation by the SEC-PAGE method results in a nonuniform distribution of protein- and humin-like fluorescence of the original HA preparation among the electrophoretic fractions. The electrophoretic fractions of the highest and medium MSs have only the main protein-like fluorescence maximum and traces of humin-like fluorescence. In the electrophoretic fraction of the lowest MS, the intensity of protein-like fluorescence is low, but the major part of humin-like fluorescence is localized there. Relationships between the intensity of protein-like fluorescence and the weight distribution of amino acids have been revealed, as well as between the degree of aromaticity and the intensity of humin-like fluorescence in electrophoretic fractions of different MSs. The obtained relationships can be useful in the interpretation of the spatial structural organization and ecological functions of soil HAs.

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

Directory of Open Access Journals (Sweden)

Wu J

2014-11-01

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

Enhancing fluorescence intensity of Ellagic acid in Borax-HCl-CTAB micelles

Science.gov (United States)

Wang, Feng; Huang, Wei; Zhang, Shuai; Liu, Guokui; Li, Kexiang; Tang, Bo

2011-03-01

Ellagic acid (C 14H 6O 8), a naturally occurring phytochemical, found mainly in berries and some nuts, has anticarcinogenic and antioxidant properties. It is found that fluorescence of Ellagic acid (EA) is greatly enhanced by micelle of cetyltrimethylammonium bromide (CTAB) surfactant. Based on this effect, a sensitive proposed fluorimetric method was applied for the determination of Ellagic acid in aqueous solution. In the Borax-HCl buffer, the fluorescence intensity of Ellagic acid in the presence of CTAB is proportional to the concentration of Ellagic acid in range from 8.0 × 10 -10 to 4.0 × 10 -5 mol L -1; and the detection limits are 3.2 × 10 -10 mol L -1 and 5.9 × 10 -10 mol L -1 excited at 266 nm and 388 nm, respectively. The actual samples of pomegranate rinds are simply manipulated and satisfactorily determined. The interaction mechanism studies argue that the negative EA-Borax complex is formed and solubilized in the cationic surfactant CTAB micelle in this system. The fluorescence intensity of EA enhances because the CTAB micelle provides a hydrophobic microenvironment for EA-Borax complex, which can prevent collision with water molecules and decrease the energy loss of EA-Borax complex.

The fluorescence spectroscopic studies on the interaction of novel aminophosphinic acids with bovine serum albumin

Energy Technology Data Exchange (ETDEWEB)

Kaboudin, B., E-mail: kaboudin@iasbs.ac.ir [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731 (Iran, Islamic Republic of); Moradi, K.; Faghihi, M.R.; Mohammadi, F. [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731 (Iran, Islamic Republic of)

2013-07-15

Six novel aminomethylphosphinic acids have been synthesized and characterized. The interaction between the aminophosphinic acids and bovine serum albumin (BSA) was investigated using fluorescence spectroscopy. The experimental results showed that the fluorescence quenching of BSA by aminophosphinic acids is a result of the formation of aminophosphinic acid–BSA complex; static quenching and non-radiative energy transferring were confirmed to result in the fluorescence quenching. The number of binding sites n, the apparent binding constant K{sub A} and the corresponding thermodynamic parameters were calculated at different temperatures. The process of binding of the aminophosphinic acid molecules to BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the complex. The effect of aminophosphinic acids on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. -- Graphical abstarct: The binding interactions of the water-soluble aminoalkylphosphinic acids APA 1–6 to bovine serum albumin (BSA) showed that the interaction process was spontaneous and the major interaction forces were found to be hydrophobic. Highlights: ► Binding of novel aminophosphinic acids with bovine serum albumin. ► Hydrophobic and hydrogen bonding attraction play major role in the binding process. ► Binding did not cause conformational changes in the protein. ► The quenching mechanism of fluorescence of BSA by aminophosphinic acids is a static quenching process.

The fluorescence spectroscopic studies on the interaction of novel aminophosphinic acids with bovine serum albumin

International Nuclear Information System (INIS)

Kaboudin, B.; Moradi, K.; Faghihi, M.R.; Mohammadi, F.

2013-01-01

Six novel aminomethylphosphinic acids have been synthesized and characterized. The interaction between the aminophosphinic acids and bovine serum albumin (BSA) was investigated using fluorescence spectroscopy. The experimental results showed that the fluorescence quenching of BSA by aminophosphinic acids is a result of the formation of aminophosphinic acid–BSA complex; static quenching and non-radiative energy transferring were confirmed to result in the fluorescence quenching. The number of binding sites n, the apparent binding constant K A and the corresponding thermodynamic parameters were calculated at different temperatures. The process of binding of the aminophosphinic acid molecules to BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the complex. The effect of aminophosphinic acids on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. -- Graphical abstarct: The binding interactions of the water-soluble aminoalkylphosphinic acids APA 1–6 to bovine serum albumin (BSA) showed that the interaction process was spontaneous and the major interaction forces were found to be hydrophobic. Highlights: ► Binding of novel aminophosphinic acids with bovine serum albumin. ► Hydrophobic and hydrogen bonding attraction play major role in the binding process. ► Binding did not cause conformational changes in the protein. ► The quenching mechanism of fluorescence of BSA by aminophosphinic acids is a static quenching process

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

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

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

Directory of Open Access Journals (Sweden)

A. Doustgani

2016-04-01

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

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.

Synergistic Combination of Unquenching and Plasmonic Fluorescence Enhancement in Fluorogenic Nucleic Acid Hybridization Probes.

Science.gov (United States)

Vietz, Carolin; Lalkens, Birka; Acuna, Guillermo P; Tinnefeld, Philip

2017-10-11

Fluorogenic nucleic acid hybridization probes are widely used for detecting and quantifying nucleic acids. The achieved sensitivity strongly depends on the contrast between a quenched closed form and an unquenched opened form with liberated fluorescence. So far, this contrast was improved by improving the quenching efficiency of the closed form. In this study, we modularly combine these probes with optical antennas used for plasmonic fluorescence enhancement and study the effect of the nanophotonic structure on the fluorescence of the quenched and the opened form. As quenched fluorescent dyes are usually enhanced more by fluorescence enhancement, a detrimental reduction of the contrast between closed and opened form was anticipated. In contrast, we could achieve a surprising increase of the contrast with full additivity of quenching of the dark form and fluorescence enhancement of the bright form. Using single-molecule experiments, we demonstrate that the additivity of the two mechanisms depends on the perfect quenching in the quenched form, and we delineate the rules for new nucleic acid probes for enhanced contrast and absolute brightness. Fluorogenic hybridization probes optimized not only for quenching but also for the brightness of the open form might find application in nucleic acid assays with PCR avoiding detection schemes.

A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH.

Science.gov (United States)

Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

2015-06-05

Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (K(a)=3582.88 M(-1)) and selectivity for fructose over glucose at pH=7.4. The sensor 1 showed a linear response toward d-fructose in the concentrations ranging from 2.5×10(-5) to 4×10(-4) mol L(-1) with the detection limit of 1.3×10(-5) mol L(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

Application of locked nucleic acid-based probes in fluorescence in situ hybridization

DEFF Research Database (Denmark)

Fontenete, Sílvia; Carvalho, Daniel R; Guimarães, Nuno

2016-01-01

of nucleic acid mimics used as mixmers in LNA-based probes strongly influence the efficiency of detection. LNA probes with 10 to 15 mers showed the highest efficiency. Additionally, the combination of 2′-OMe RNA with LNA allowed an increase on the fluorescence intensities of the probes. Overall......Fluorescence in situ hybridization (FISH) employing nucleic acid mimics as probes is becoming an emerging molecular tool in the microbiology area for the detection and visualization of microorganisms. However, the impact that locked nucleic acid (LNA) and 2′-O-methyl (2′-OMe) RNA modifications have...

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.

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.

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.

Development of polylactic acid-based materials through reactive modification

Science.gov (United States)

Fowlks, Alison Camille

2009-12-01

Polylactic acid (PLA)-based systems have shown to be of great potential for the development of materials requiring biobased content, biodegradation, and sufficient properties. The efforts in this study are directed toward addressing the current research need to overcome some of the inherent drawbacks of PLA. To meet this need, reactive extrusion was employed to develop new materials based on PLA by grafting, compounding, and polymer blending. In the first part of this work, maleic anhydride (MA) was grafted onto PLA by reactive extrusion. Two structurally different peroxides were used to initiate grafting and results were reported on the basis of grafting, molecular weight, and thermal behavior. An inverse relationship between degree of grafting and molecular weight was established. It was also found that, regardless of peroxide type, there is an optimum peroxid-to-MA ratio of 0.5:2 that promotes maximum grafting, beyond which degradation reactions become predominant. Overall, it was found that the maleated copolymer (MAPLA) could be used as an interfacial modifier in PLA-based composites. Therefore, MAPLA was incorporated into PLA-talc composites in varying concentrations. The influence of the MAPLA addition on the mechanical and thermal behavior was investigated. When added in an optimum concentration, MAPLA improved the tensile strength and crystallization of the composite. Furthermore, microscopic observation confirmed the compatibilization effect of MAPLA in PLA-talc composites. Vinyltrimethoxysilane was free-radically grafted onto the backbone of PLA and subsequently moisture crosslinked. The effects of monomer, initiator, and catalyst concentration on the degree of crosslinking and the mechanical and thermal properties were investigated. The presence of a small amount of catalyst showed to be a major contributor to the crosslinking formation in the time frame investigated, shown by an increase in gel content and decrease in crystallinity. Furthermore

Sensitive determination of nucleic acids using organic nanoparticle fluorescence probes

Science.gov (United States)

Zhou, Yunyou; Bian, Guirong; Wang, Leyu; Dong, Ling; Wang, Lun; Kan, Jian

2005-06-01

This paper describes the preparation of organic nanoparticles by reprecipitation method under sonication and vigorous stirring. Transmission electron microscopy (TEM) was used to characterize the size and size distribution of the luminescent nanoparticles. Their average diameter was about 25 nm with a size variation of ±18%. The fluorescence decay lifetime of the nanoparticles also was determined on a self-equipped fluorospectrometer with laser light source. The lifetime (˜0.09 μs) of nanoparticles is about three times long as that of the monomer. The nanoparticles were in abundant of hydrophilic groups, which increased their miscibility in aqueous solution. These organic nanoparticles have high photochemical stability, excellent resistance to chemical degradation and photodegradation, and a good fluorescence quantum yield (25%). The fluorescence can be efficiently quenched by nucleic acids. Based on the fluorescence quenching of nanoparticles, a fluorescence quenching method was developed for determination of microamounts of nucleic acids by using the nanoparticles as a new fluorescent probe. Under optimal conditions, maximum fluorescence quenching is produced, with maximum excitation and emission wavelengths of 345 and 402 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-19.0 μg ml -1 for calf thymus DNA (ct-DNA) and 0.3-19.0 μg ml -1 for fish sperm DNA (fs-DNA). The corresponding detection limits are 0.25 μg ml -1 for ct-DNA and 0.17 μg ml -1 for fs-DNA. The relative standard deviation of six replicate measurements is 1.3-2.1%. The method is simple, rapid and sensitive with wide linear range. The recovery and relative standard deviation are very satisfactory.

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.

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.

Residual wood polymers facilitate compounding of microfibrillated cellulose with poly(lactic acid) for 3D printer filaments

Science.gov (United States)

Winter, Armin; Mundigler, Norbert; Holzweber, Julian; Veigel, Stefan; Müller, Ulrich; Kovalcik, Adriana; Gindl-Altmutter, Wolfgang

2017-12-01

Microfibrillated cellulose (MFC) is a fascinating material with an obvious potential for composite reinforcement due to its excellent mechanics together with high specific surface area. However, in order to use this potential, commercially viable solutions to important technological challenges have to be found. Notably, the distinct hydrophilicity of MFC prevents efficient drying without loss in specific surface area, necessitating storage and processing in wet condition. This greatly hinders compounding with important technical polymers immiscible with water. Differently from cellulose, the chemistry of the major wood polymers lignin and hemicellulose is much more diverse in terms of functional groups. Specifically, the aromatic moieties present in lignin and acetyl groups in hemicellulose provide distinctly less polar surface-chemical functionality compared to hydroxyl groups which dominate the surface-chemical character of cellulose. It is shown that considerable advantages in the production of MFC-filled poly(lactic acid) filaments for three-dimensional printing can be obtained through the use of MFC containing residual lignin and hemicellulose due to their advantageous surface-chemical characteristics. Specifically, considerably reduced agglomerations of MFC in the filaments in combination with improved printability and improved toughness of printed objects are achieved. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

Residual wood polymers facilitate compounding of microfibrillated cellulose with poly(lactic acid) for 3D printer filaments.

Science.gov (United States)

Winter, Armin; Mundigler, Norbert; Holzweber, Julian; Veigel, Stefan; Müller, Ulrich; Kovalcik, Adriana; Gindl-Altmutter, Wolfgang

2018-02-13

Microfibrillated cellulose (MFC) is a fascinating material with an obvious potential for composite reinforcement due to its excellent mechanics together with high specific surface area. However, in order to use this potential, commercially viable solutions to important technological challenges have to be found. Notably, the distinct hydrophilicity of MFC prevents efficient drying without loss in specific surface area, necessitating storage and processing in wet condition. This greatly hinders compounding with important technical polymers immiscible with water. Differently from cellulose, the chemistry of the major wood polymers lignin and hemicellulose is much more diverse in terms of functional groups. Specifically, the aromatic moieties present in lignin and acetyl groups in hemicellulose provide distinctly less polar surface-chemical functionality compared to hydroxyl groups which dominate the surface-chemical character of cellulose. It is shown that considerable advantages in the production of MFC-filled poly(lactic acid) filaments for three-dimensional printing can be obtained through the use of MFC containing residual lignin and hemicellulose due to their advantageous surface-chemical characteristics. Specifically, considerably reduced agglomerations of MFC in the filaments in combination with improved printability and improved toughness of printed objects are achieved.This article is part of a discussion meeting issue 'New horizons for cellulose nanotechnology'. © 2017 The Author(s).

Specific Mechanical Energy and Thermal Degradation of Poly(lactic acid and Poly(caprolactone/Date Pits Composites

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A. A. Mohamed

2018-01-01

Full Text Available The compatibility of date pits (DP with polylactic acid (PLA or polycaprolactone (PCL is investigated. Composites were prepared by compounding PLA or PCL with date pits at 10, 20, 30, and 40% wt/wt and extruded. Wheat vital gluten (VG was also used as a filler and in combination with DP. The specific mechanical energy (SME was calculated and the composites thermal properties were tested using DSC (peak temperature, enthalpic relaxation, and glass transition and TGA (degradation temperature and mechanism and degradation kinetics. Because DP is hard filler, the SME of PCL-DP composites increased as the amount of filler increased. At 40% fill, the SME decreased due to the lubricating effect of oil found naturally in DP. As illustrated by lower SME, PLA composites exhibited softer texture because PLA is harder than DP. The DSC melting peak temperature of both polymers has increased at higher DP; however, PLA exhibited enthalpic relation between 66 and 68°C. The TGA profile of the composites displayed two distinct peaks versus one peak for the pure polymer. The degradation kinetics showed multistep process for the composites and one-step process for the pure polymer. The utilization of date pits as a hard filler in developing biodegradable plastics is good for the environment and a value added for the date industry.

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

International Nuclear Information System (INIS)

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

2016-01-01

Poly(lactic acid) (PLA) is a well-known biodegradable polymer with strong potential application in food packaging industry. In this paper, samples of PLA clamshell for tomatoes packaging were exposed with 60 CO γ-ray's source (1.33 MeV) at different dose levels (0, 10, 60, 150, 300, and 600 kGy), at room temperature and in presence of air. The physicochemical properties of neat PLA and sample exposed to gamma irradiation were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile measurements. Results show as the dose increases, the molecular weight (M w ), melting temperature (T m ), tensile strength and elongation at break decreased. However, the tensile modulus increased with increasing doses. The surface of PLA clamshells was degraded (scratches and minor cracks) when samples were exposed to doses greater than 60 kGy. - Highlights: • The gamma irradiation effects on PLA clamshells were studied. • DSC, XRD, NMR and FTIR analysis were used for PLA clamshell characterization. • The M w , T m , strength and elongation of the irradiated PLA clamshells decreased. • The tensile modulus increased with increasing gamma doses. • The Surface of PLA clamshell showed scratches and minor cracks.

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

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M.R. Nurul Fazita

2015-08-01

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

Effect of Rhizopus oryzae Fermentation on Kenaf-Based Polylactic Acid’s Monomer

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Nur Aimi Mohd Nasir

2011-12-01

Full Text Available Kenaf biomass is the potential as raw materials used to produce polylactic acid's monomer which is lactic acid via fermentation by Rhizopus oryzae. Kenaf biomass' structure is complex due to its lignin and cellulose content. This matter had encouraged it to undergo pre- treatment process as the initial step before fermentation process can be done. In this paper, kenaf biomass was treated with dilute sulphuric acid (H2SO4 to hydrolyze the cellulose content in it as well as to convert the cellulose into glucose- a carbon source for Rhizopus to grow. Then, the fermentation process was carried out in shake flask for 3 days at pH 6. Several conditions for fermentation process had been chosen which were 25oC at 150 rpm, 25 oC at 200 rpm, 37 oC at 150 rpm and 37oC at 200 rpm. In this fermentation process, 0.471 g/L, 0.428 g/L, 0.444 g/L and 0.38 g/L of lactic acid was produced respectively. Sample at 25oC at 200 rpm produced maximum amount of lactic acid compared to others.ABSTRAK: Biojisim kenaf berpotensi sebagai bahan mentah dalam penghasilan monomer asid polylactic (poliester alifatik termoplastik diterbitkan daripada sumber boleh diperbaharu seperti kanji jagung yang merupakan asid laktik menerusi penapaian oleh Rhizopus oryzae (sejenis fungus yang hidup dalam jirim organik yang telah mati. Struktur biojisim kenaf adalah kompleks disebabkan kandungan lignin dan selulosanya. Hal ini menyebabkan ia perlu melalui proses pra-rawatan sebagai langkah awal sebelum proses penapaian dijalankan. Dalam kertas ini, biojirim kenaf dirawat dengan asid sulfurik (H2SO4 yang dicairkan untuk menghidrolisis kandungan selulosa di dalamnya di samping menukar selulosa menjadi glukosa - sumber karbon bagi tumbesaran Rhizopus. Kemudian, proses penapaian dijalankan di dalam kelalang goncang selama 3 hari pada pH 6. Beberapa ciri proses penapaian telah dipilih iaitu 25 oC pada 150 rpm, 25 oC pada 200 rpm, 37 oC pada 150 rpm dan 37 oC pada 200 rpm. Dalam proses penapaian

Release of carbon nanoparticles of different size and shape from nanocomposite poly(lactic) acid film into food simulants.

Science.gov (United States)

Velichkova, Hristiana; Kotsilkov, Stanislav; Ivanov, Evgeni; Kotsilkova, Rumiana; Gyoshev, Stanislav; Stoimenov, Nikolay; Vitanov, Nikolay K

2017-06-01

Poly(lactic) acid (PLA) film with 2 wt% mixed carbon nanofillers of graphene nanoplates (GNPs) and multiwall carbon nanotubes (MWCNTs) in a weight ratio of 1:1 with impurities of fullerene and carbon black (CB) was produced by layer-to-layer deposition and hot pressing. The release of carbon nanoparticles from the film was studied at varying time-temperature conditions and simulants. Migrants in simulant solvents were examined with laser diffraction analysis and transmission electron microscopy (TEM). Film integrity and the presence of migrants on the film surfaces were visualised by scanning electron microscopy (SEM). The partial dissolution of PLA polymer in the solvents was confirmed by swelling tests and differential scanning calorimetry (DSC). Nanoparticle migrants were not detected in the simulants (at the LOD 0.020 μm of the laser diffraction analysis) after migration testing at 40°C for 10 days. However, high-temperature migration testing at 90°C for 4 h provoked a release of GNPs from the film into ethanol, acetic acid and oil-based food simulants. Short carbon nanotubes were observed rarely to release in the most aggressive acetic acid solvent. Obviously, the enhanced molecular mobility at temperatures above the glass transition and partial dissolution of PLA polymer by the food simulant facilitate the diffusion processes. Moreover, shape, size and concentration of nanoparticles play a significant role. Flexible naked GNPs (lateral size 100-1000 nm) easily migrate when the polymer molecules exhibit enhanced mobility, while fibrous MWCNTs (> 1 μm length) formed entangled networks on the film surfaces as the PLA polymer is partly dissolved, preventing their release into food simulants. The impurities of fullerenes and CB (5-30 nm) were of minor concentration in the polymer, therefore their migration is low or undetectable. The total amount of released migrants is below overall migration limits.

Mechanical properties, morphology, and hydrolytic degradation behavior of polylactic acid / natural rubber blends

Science.gov (United States)

Buys, Y. F.; Aznan, A. N. A.; Anuar, H.

2018-01-01

Due to its biodegradability and renewability, polylactic acid (PLA) has been receiving enormous attention as a potential candidate to replace petroleum based polymers. However, PLA has limitation due to its inherent brittleness. In order to overcome this limitation, blending PLA with elastomeric materials such as natural rubber (NR) are commonly reported. In previous, several researches on PLA/NR blend had been reported, with most of them evaluated the mechanical properties. On the other hand, study of degradation behavior is significance of importance, as controlling materials degradation is required in some applications. This research studied the effect of blend composition on mechanical properties, morphology development, and hydrolytic degradation behavior of PLA/NR blends. Various compositions of PLA/NR blends were prepared by melt blending technique. Tensile test and impact test of the blends were performed to evaluate the mechanical properties. Addition of NR improved the elongation at break and impact strength of the blends, but reduced the tensile strength and stiffness of the specimens. Dynamic Mechanical Analysis (DMA) measurements of the blends displayed two peaks at temperature -70˚C which corresponded to T g of NR and 65˚C which corresponded to T g of PLA. Field Emission Scanning Electron Microscopy (FE-SEM) micrograph of 70/30 PLA/NR specimen also showed two distinct phases, which lead to indication that PLA/NR blends are immiscible. Hydrolytic degradation behavior was evaluated by measuring the remaining weight of the samples immersed in sodium hydroxide solution for a predetermined times. It was shown that the degradation behavior of PLA/NR blends is affected by composition of the blends, with 100 PLA and 70/30 PLA/NR blend showed the fastest degradation rate and 100 NR displayed the slowest one.

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

Science.gov (United States)

Ma, Wenguang

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-01

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

Water and UV degradable lactic acid polymers

Science.gov (United States)

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

1996-10-08

A water and UV light degradable copolymer is described made from monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

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

Science.gov (United States)

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

2016-08-20

In this work, poly(lactic acid), PLA and thermoplastic starch, TPS blends (with a fixed content of 30wt.% TPS) were prepared by melt extrusion process to increase the low ductile properties of PLA. The TPS used contains an aliphatic/aromatic biodegradable polyester (AAPE) that provides good resistance to aging and moisture. This blend provides slightly improved ductile properties with an increase in elongation at break of 21.5% but phase separation is observed due to the lack of strong interactions between the two polymers. Small amounts of maleinized linseed oil (MLO) can positively contribute to improve the ductile properties of these blends by a combined plasticizing-compatibilizing effect. The elongation at break increases over 160% with the only addition of 6phr MLO. One of the evidence of the plasticizing-compatibilizing effect provided by MLO is the change in the glass transition temperature (Tg) with a decrease of about 10°C. Field emission scanning electron microscopy (FESEM) of PLA-TPS blends with varying amounts of maleinized linseed oil also suggests an increase in compatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Indirect fluorescence detection of native amino acids in capillary zone electrophoresis

Energy Technology Data Exchange (ETDEWEB)

Kuhr, W.G.; Yeung, E.S.

1988-09-01

Amino acids are but one of several important classes of small chemical compounds in biological chemistry that have an inherent lack of analytically useful physical properties. Amino acids, peptides, fatty acids, sugars, many mono-, di-, and tricarboxylic acids, and phosphorylated intermediates in glycolysis and metabolism show little, if any, UV or visible absorption, fluorescence, or electrochemical activity. As the emphasis of biochemical research shifts to smaller samples where, for example, picomolar quantities of amino acids are analyzed in gas phase protein sequencing or in microliter samples of the extracellular fluid of the mammalian brain, the analytical problem becomes even more challenging due to the small volume of sample available for analysis. In this work, laser-induced fluorescence spectroscopy is performed on-column to detect the bands separated with capillary zone electrophoresis (CZE). CZE is an instrumental form of zone electrophoresis where chemical species are separated purely on the basis of their electrophoretic mobility, since no supporting gel is utilized. Both anions and cations can be separated in the same run because of the large electroosmotic flow generated in small diameter capillaries. This technique has already been used successfully in the rapid, efficient separation of dansyl-amino acids.

Fabrication and imaging study of ultrasound/fluorescence bi-modal contrast agent based on polymeric microbubbles

International Nuclear Information System (INIS)

Xing Zhanwen; Ke Hengte; Wang Jinrui; Zhao Bo; Qu Enze; Yue Xiuli; Dai Zhifei

2013-01-01

Objective: To fabricate an ultrasound/fluorescence bi-modal contrast agent by encapsulating fluorescent quantum dots into polymeric ultrasound contrast agent microbubbles. Methods: Polylactic acid (PLA, 500 mg), (1R)-(+)-camphor (50 mg) and CdSe/ZnS quantum dots (0.5 ml, 2.3 μmol/L)were dissolved or dispersed in dichloromethane (10 ml) to form in an organic phase. Ammonium carbonate solution and poly (vinyl alcohol) solution were employed as the internal and external water phase, respectively. The fluorescent microbubbles were generated using double emulsion solvent evaporation and lyophilization methods. The morphology and illumination were characterized by scanning electron microscopy (SEM) and fluorescence spectrophotometry. Synchronized contrast-enhanced ultrasound and fluorescence imaging was acquired by injecting fluorescent microbubbles into the silicone tube coupled to a self-made ultrasound/fluorescence imaging device. Ultrasound/fluorescence bi-modal in vivo imaging was acquired on the kidney of New Zealand rabbits and suckling mice. Results: The fluorescent microbubbles were hollow spheres with an averaged diameter of (1.62 ± 1.47) μm. More than 99% of these microbubbles were less than 8 μm in diameter, which met the size criteria for ultrasound contrast agents. The fluorescence emission peak of the microbubbles appeared at 632 nm, indicating that good luminescence properties of quantum dots were maintained. In vitro ultrasound/fluorescence imaging showed no echoic signal when the silicone tube was filled with saline, but there was a strong echo when filled with fluorescent microbubbles. The liquid column with fluorescent microbubbles emitted red luminescence under ultraviolet irradiation. The kidney of the rabbit was remarkably enhanced after the administration of fluorescent microbubbles. Bright fluorescence could be observed at the injection site of the suckling mice via subcutaneous injection. Conclusions: A bi-modal but single contrast agent

Poly(o-phenylenediamine) colloid-quenched fluorescent oligonucleotide as a probe for fluorescence-enhanced nucleic acid detection.

Science.gov (United States)

Tian, Jingqi; Li, Hailong; Luo, Yonglan; Wang, Lei; Zhang, Yingwei; Sun, Xuping

2011-02-01

In this Letter, we demonstrate that chemical oxidation polymerization of o-phenylenediamine (OPD) by potassium bichromate at room temperature results in the formation of submicrometer-scale poly(o-phenylenediamine) (POPD) colloids. Such colloids can absorb and quench dye-labeled single-stranded DNA (ssDNA) very effectively. In the presence of a target, a hybridization event occurs, which produces a double-stranded DNA (dsDNA) that detaches from the POPD surface, leading to recovery of dye fluorescence. With the use of an oligonucleotide (OND) sequence associated with human immunodeficiency virus (HIV) as a model system, we demonstrate the proof of concept that POPD colloid-quenched fluorescent OND can be used as a probe for fluorescence-enhanced nucleic acid detection with selectivity down to single-base mismatch.

Polylactic acid (PLA)/Silver-NP/VitaminE bionanocomposite electrospun nanofibers with antibacterial and antioxidant activity

Science.gov (United States)

Munteanu, Bogdanel Silvestru; Aytac, Zeynep; Pricope, Gina M.; Uyar, Tamer; Vasile, Cornelia

2014-10-01

The antibacterial property of silver nanoparticles (Ag-NPs) and the antioxidant activity of Vitamin E have been combined by incorporation of these two active components within polylactic acid (PLA) nanofibers via electrospinning (PLA/Ag-NP/VitaminE nanofibers). The morphological and structural characterizations of PLA/Ag-NP/VitaminE nanofibers were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy and X-ray diffraction. The average fiber diameter was 140 ± 60 nm, and the size of the Ag-NP was 2.7 ± 1.5 nm. PLA/Ag-NP/VitaminE nanofibers inhibited growth of Escherichia coli, Listeria monocytogenes and Salmonella typhymurium up to 100 %. The amount of released Ag ions from the nanofibers immersed in aqueous solution was determined by Inductively Coupled Plasma Mass Spectrometry, and it has been observed that the release of Ag ions was kept approximately constant after 10 days of immersion. The antioxidant activity of PLA/Ag-NP/VitaminE nanofibers was evaluated according to DPPH (2,2-diphenyl-1-picrylhydrazyl) method and determined as 94 %. The results of the tests on fresh apple and apple juice indicated that the PLA/Ag/VitaminE nanofiber membrane actively reduced the polyphenol oxidase activity. The multifunctional electrospun PLA nanofibers incorporating Ag-NP and Vitamin E may be quite applicable in food packaging due to the extremely large surface area of nanofibers along with antibacterial and antioxidant activities. These materials could find application in food industry as a potential preservative packaging for fruits and juices.

Characterization of napthenic acids in oil sands process-affected waters using fluorescence technology

International Nuclear Information System (INIS)

Brown, L.; Alostaz, M.; Ulrich, A.

2009-01-01

Process-affected water from oil sands production plants presents a major environmental challenge to oil sands operators due to its toxicity to different organisms as well as its corrosiveness in refinery units. This abstract investigated the use of fluorescence excitation-emission matrices to detect and characterize changes in naphthenic acid in oil sands process-affected waters. Samples from oil sands production plants and storage ponds were tested. The study showed that oil sands naphthenic acids show characteristic fluorescence signatures when excited by ultraviolet light in the range of 260 to 350 mm. The signal was a unique attribute of the naphthenic acid molecule. Changes in the fluorescence signature can be used to determine chemical changes such as degradation or aging. It was concluded that the technology can be used as a non-invasive continuous water quality monitoring tool to increase process control in oil sands processing plants

Reliable porcine coronary model of chronic total occlusion using copper wire stents and bioabsorbable levo-polylactic acid polymer.

Science.gov (United States)

Sim, Doo Sun; Jeong, Myung Ho; Cha, Kyoung Rae; Park, Suk Ho; Park, Jong Oh; Shin, Young Min; Shin, Heungsoo; Hong, Young Joon; Ahn, Youngkeun; Schwartz, Robert S; Kang, Jung Chaee

2012-12-01

Chronic total occlusion (CTO) remains a challenge in interventional cardiology. We investigated the feasibility and reliability of copper wire stents and levo-polylactic acid (l-PLA) as a means of CTO induction in a porcine model. In one group of 20 swine, copper stents were crimped on a 3.0mm angioplasty balloon and inserted into the mid-left anterior descending coronary artery (LAD). In the other group of 20 swine, l-PLA was wrapped on a guidewire and pushed into the distal LAD with a 3.0mm balloon catheter to induce embolization. Of 20 swine which underwent copper stent implantation, 13 died of stent thrombosis. In the remaining 7 swine, total or near total occlusion with collateral circulation was observed at 5 weeks. Of 20 swine which underwent l-PLA embolization, 4 died of ventricular fibrillation during or shortly after the procedure. Serial histopathologic studies showed complete absorption of the polymer with replacement by fibrotic tissue approximately 4 weeks following the polymer implantation. CTO could be reliably induced in porcine coronary arteries by copper stents and l-PLA. These models may support investigation of new percutaneous devices to facilitate CTO interventions. Copyright © 2012 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

Oliveira, Juliano Elvis; Medeiros, Eliton Souto; Cardozo, Lucio; Voll, Fernando; Madureira, Ed Hoffmann; Mattoso, Luiz Henrique Capparelli; Assis, Odilio Benedito Garrido

2013-01-01

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

Effect of combining cellulose nanocrystals and graphene nanoplatelets on the properties of poly(lactic acid based films

Directory of Open Access Journals (Sweden)

S. Montes

2018-06-01

Full Text Available In the present work, cellulose nanocrystals (CNC and graphene nanoplatelets (GR were combined in two different ratios and incorporated into polylactic acid (PLA by melt blending technique, at a total loading level of 1 wt%. The obtained PLA-CNC/GR nanocomposites were further processed by hot pressing for manufacturing films. For comparison purposes, PLA-CNC, PLA-GR and PLA-T (PLA blended with the organic surfactant Triton X-100 compositions were also prepared following the same procedure. The produced materials were characterized by several techniques, including Field-Emission Scanning Electron Microscopy (FE-SEM. The mechanical properties assessment showed an increase of 8 and 11% in the Young’s modulus and tensile strength respectively for PLA- CNC/GR (ratio 50/50 film compared to PLA-T. The thermal properties were also positively influenced by the incorporation of both nanofillers. Similarly, the gas barrier properties were improved by 23% in Oxygen Transmission Rate (OTR for films containing simultaneously CNC and GR. Finally, the antifungal properties were evaluated against Aspergillus Niger finding a superior antifungal activity in the CNC/GR hybrid films. The incorporation of CNC and GR in PLA showed a favourable impact in the overall properties of the obtained materials with only 1 wt% of nanofiller content. These results suggest that CNC/GR hybrid nanocomposites have a considerable potential in agricultural films or in food packaging trays applications.

Preparation and Characterization of Composites Based on Polylactic Acid and Beeswax with Improved Water Vapor Barrier Properties.

Science.gov (United States)

Lim, Jung Hoon; Kim, Jeong Ae; Ko, Jung A; Park, Hyun Jin

2015-11-01

Beeswax and a plasticizer (ATBC) were added to polylactic acid (PLA) films in order to enhance the water vapor barrier properties of the films. Beeswax improved the barrier properties; the water vapor permeability in the composite containing 1% beeswax was 58% lower than that of the neat PLA. Fourier transform infrared spectroscopy and X-ray diffraction analysis revealed that the incorporation of beeswax and ATBC had so little effect on the PLA structure. In addition, the structure of PLA did not vary substantially with the additions. The surfaces of the composites were examined by using field emission scanning electron microscopy. Differential scanning calorimetry results showed that the degree of crystallinity of the PLA films increased with the addition of beeswax and ATBC. However, the tensile strength and elongation at break of the composites containing beeswax were up to approximately 50% lower than those of the neat PLA. Although further study is needed to improve the mechanical properties, the aforementioned results showed that the PLA barrier properties can be improved by the incorporation of a small amount of beeswax and ATBC. The results of this study can be applied for the preparation of PLA composite films with improved barrier properties. Such biodegradable films are extremely useful for applications in the food packaging industry. © 2015 Institute of Food Technologists®

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

Science.gov (United States)

Han, Hyoung Soon; You, Jung-Min; Jeong, Haesang; Jeon, Seungwon

2013-11-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-11-01

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

Dual fluorescence of N-phenylanthranilic acid: Effect of solvents, pH and β-cyclodextrin

Science.gov (United States)

Rajendiran, N.; Balasubramanian, T.

2007-11-01

Spectral characteristics of N-phenylanthranilic acid (NPAA) have been studied in different solvents, pH and β-cyclodextrin (β-CD) and compared with anthranilic acid (2-aminobenzoic acid, 2ABA). In all solvents a dual fluorescence is observed in NPAA, whereas 2ABA gives single emission. Combining the results observed in the absorption, fluorescence emission and fluorescence excitation spectra, it is found that strong intramolecular hydrogen bonding (IHB) interactions present in NPAA molecule. The inclusion complex of NPAA with β-CD is analysed by UV-vis, fluorimetry, FT-IR, 1H NMR, scanning electron microscope and AM 1 method. The above spectral studies show that NPAA forms a 1:1 inclusion complex with β-CD and COOH group present in the β-CD cavity. A mechanism is proposed to explain the inclusion process.

Dual fluorescence of N-phenylanthranilic acid: Effect of solvents, pH and beta-cyclodextrin.

Science.gov (United States)

Rajendiran, N; Balasubramanian, T

2007-11-01

Spectral characteristics of N-phenylanthranilic acid (NPAA) have been studied in different solvents, pH and beta-cyclodextrin (beta-CD) and compared with anthranilic acid (2-aminobenzoic acid, 2ABA). In all solvents a dual fluorescence is observed in NPAA, whereas 2ABA gives single emission. Combining the results observed in the absorption, fluorescence emission and fluorescence excitation spectra, it is found that strong intramolecular hydrogen bonding (IHB) interactions present in NPAA molecule. The inclusion complex of NPAA with beta-CD is analysed by UV-vis, fluorimetry, FT-IR, (1)H NMR, scanning electron microscope and AM 1 method. The above spectral studies show that NPAA forms a 1:1 inclusion complex with beta-CD and COOH group present in the beta-CD cavity. A mechanism is proposed to explain the inclusion process.

Electrospun Poly(lactic acid)-Based Fibrous Nanocomposite Reinforced by Cellulose Nanocrystals: Impact of Fiber Uniaxial Alignment on Microstructure and Mechanical Properties.

Science.gov (United States)

Huan, Siqi; Liu, Guoxiang; Cheng, Wanli; Han, Guangping; Bai, Long

2018-03-12

Uniform poly(lactic acid)/cellulose nanocrystal (PLA/CNC) fibrous mats composed of either random or aligned fibers reinforced with up to 20 wt % CNCs were successfully produced by two different electrospinning processes. Various concentrations of CNCs could be stably dispersed in PLA solution prior to fiber manufacture. The microstructure of produced fibrous mats, regardless of random or aligned orientation, was transformed from smooth to nanoporous surface by changing CNC loading levels. Aligning process through secondary stretching during high-speed collection can also affect the porous structure of fibers. With the same CNC loading, fibrous mats produced with aligned fibers had higher degree of crystallinity than that of fibers with random structure. The thermal properties and mechanical performances of PLA/CNC fibrous mats can be enhanced, showing better enhancement effect of aligned fibrous structure. This results from a synergistic effect of the increased crystallinity of fibers, the efficient stress transfer from PLA to CNCs, and the ordered arrangement of electrospun fibers in the mats. This research paves a way for developing an electrospinning system that can manufacture high-performance CNC-enhanced PLA fibrous nanocomposites.

Graphene Oxide and Gadolinium-Chelate Functionalized Poly(lactic acid) Nanocapsules Encapsulating Perfluorooctylbromide for Ultrasound/Magnetic Resonance Bimodal Imaging Guided Photothermal Ablation of Cancer.

Science.gov (United States)

Li, Zhenglin; Ke, Hengte; Wang, Jinrui; Miao, Zhaohua; Yue, Xiuli

2016-03-01

This paper successfully fabricated a novel multifunctional theranostic agent (PFOB@PLA/GO/Gd-DTPA NCs) by loading perfluorooctylbromide (PFOB) into poly(lactic acid) (PLA) nanocapsules (NCs) followed by surface functionalization with graphene oxide (GO) and gadolinium-chelate (Gd-DTPA). It was found that the resulting nanoagent could serve as a contrast agent simultaneously to enhance ultrasound (US) and magnetic resonance imaging (MRI). Benefiting from the strong absorption in the near infrared (NIR) region, the nanocapsules could efficiently kill cancer cells under NIR laser irradiation. Thus, such a single theranostic agent with the combination of realtime US imaging and high-resolution MR imaging could achieve great therapeutic effectiveness without systemic damage to the body. In addition, the cytotoxicity assay on HUVEC cells revealed a good biocompatibility of PFOB@PLA/GO/Gd-DTPA NCs, showing that the versatile nanocapsule system may hold great potential as an effective nanoplatform for contrast enhanced imaging guided photothermal therapy.

Near-infrared fluorescent aza-BODIPY dye-loaded biodegradable polymeric nanoparticles for optical cancer imaging

International Nuclear Information System (INIS)

Hamon, Casey L.; Dorsey, Christopher L.; Özel, Tuğba; Barnes, Eugenia M.; Hudnall, Todd W.; Betancourt, Tania

2016-01-01

Nanoparticles are being readily investigated as carriers for the delivery of imaging and therapeutic agents for the detection, monitoring, and treatment of cancer and other diseases. In the present work, the preparation of biodegradable polymeric nanoparticles loaded with a near-infrared fluorescent aza-boron dipyrromethene (NIR-BODIPY) derivative, and their use as contrast agents for optical imaging in cancer are described. Nanoparticles were prepared by nanoprecipitation of amphiphilic block copolymers of poly(lactic acid) and poly(ethylene glycol). The size, morphology, dye loading, spectral properties, quantum yield, cytocompatibility, and in vitro NIR imaging potential of the nanoparticles in breast and ovarian cancer cells were evaluated. Spherical nanoparticles of 30–70 nm in diameter were loaded with 0.73 w/w% BODIPY derivative. At this loading, the dye presented a fluorescence quantum yield in the same order of magnitude as in solution. Nanoparticle suspensions at concentrations up to 580 μg/mL were cytocompatible to breast (MDA-MB-231) and ovarian (SKOV-3 and Caov-3) cancer cells after a four-hour incubation period. Fluorescence microscopy images demonstrated the ability of the nanoparticles to act as imaging agents in all three cell lines in as little as 1 hour. The results shown indicate the potential of these NIR-BODIPY-loaded nanoparticles as contrast agents for near-infrared optical imaging in cancer.Graphical abstract

Near-infrared fluorescent aza-BODIPY dye-loaded biodegradable polymeric nanoparticles for optical cancer imaging

Energy Technology Data Exchange (ETDEWEB)

Hamon, Casey L.; Dorsey, Christopher L. [Texas State University, Department of Chemistry and Biochemistry (United States); Özel, Tuğba [Texas State University, Materials Science, Engineering, and Commercialization Program (United States); Barnes, Eugenia M.; Hudnall, Todd W.; Betancourt, Tania, E-mail: tb26@txstate.edu [Texas State University, Department of Chemistry and Biochemistry (United States)

2016-07-15

Nanoparticles are being readily investigated as carriers for the delivery of imaging and therapeutic agents for the detection, monitoring, and treatment of cancer and other diseases. In the present work, the preparation of biodegradable polymeric nanoparticles loaded with a near-infrared fluorescent aza-boron dipyrromethene (NIR-BODIPY) derivative, and their use as contrast agents for optical imaging in cancer are described. Nanoparticles were prepared by nanoprecipitation of amphiphilic block copolymers of poly(lactic acid) and poly(ethylene glycol). The size, morphology, dye loading, spectral properties, quantum yield, cytocompatibility, and in vitro NIR imaging potential of the nanoparticles in breast and ovarian cancer cells were evaluated. Spherical nanoparticles of 30–70 nm in diameter were loaded with 0.73 w/w% BODIPY derivative. At this loading, the dye presented a fluorescence quantum yield in the same order of magnitude as in solution. Nanoparticle suspensions at concentrations up to 580 μg/mL were cytocompatible to breast (MDA-MB-231) and ovarian (SKOV-3 and Caov-3) cancer cells after a four-hour incubation period. Fluorescence microscopy images demonstrated the ability of the nanoparticles to act as imaging agents in all three cell lines in as little as 1 hour. The results shown indicate the potential of these NIR-BODIPY-loaded nanoparticles as contrast agents for near-infrared optical imaging in cancer.Graphical abstract.

Combined fluorescence and electrochemical investigation on the binding interaction between organic acid and human serum albumin

Institute of Scientific and Technical Information of China (English)

CHEN Yan-Min; GUO Liang-Hong

2009-01-01

Human serum albumin (HSA) is a plasma protein responsible for the binding and transport of fatty acids and a variety of exogenous chemicals such as drugs and environmental pollutants. Such binding plays a crucial role in determining the ADME (absorption, distribution, metabolism, and excretion) and bioavailability of the pollutants. We report investigation on the binding interaction between HSA and acetic acid (C2), octanoic acid (C8) and dodecanoic acid (C12) by the combination of site-specific fluorescent probe, tryptophan intrinsic fluorescence and tyrosine electrochemistry. Two fluorescent probes, dansylamide and dansyl-L-proline, were employed in the displacement measurement to study fatty acid interaction with the two drug-binding sites on HSA. Intrinsic fluorescence of tryptophan in HSA was monitored upon addition of the fatty acids into HSA. Electrocatalyzed response of the tyrosine residues in HSA by a redox mediator was used to investigate the binding interaction. Qualitatively, observations made by the three approaches are very similar. HSA did not show any change in either fluorescence or electrochemistry after mixing with C2, suggesting there is no significant interaction with the short-chain fatty acid. For C8, the measured signal dropped in a single-exponential fashion, indicative of independent and non-cooperative binding. The calculated association constant and binding ratio is 3.1×106 L/mol and 1 with drug binding Site I, 1.1×107 L/mol and 1 with Site II, and 7.0×104 L/mol and 4 with the tryptophan site. The measurement with C12 displayed multiple phases of fluorescence change, suggesting cooperativity and allosteric effect of C12 binding. These results correlate well with those obtained by the established methods, and validate the new approach as a viable tool to study the interactions of environmental pollutants with biological molecules.

Fluorescence properties of 3-amino phenylboronic acid and its interaction with glucose and ZnS:Cu quantum dots.

Science.gov (United States)

Kur-Kowalska, Karolina; Przybyt, Małgorzata; Ziółczyk, Paulina; Sowiński, Przemysław; Miller, Ewa

2014-08-14

Preliminary results of a study of the interaction between 3-amino phenylboronic acid and glucose or ZnS:Cu quantum dots are presented in this paper. ZnS:Cu quantum dots with mercaptopropionic acid as a capping agent were obtained and characterized. Quenching of 3-amino phenylboronic acid fluorescence was studied by steady-state and timeresolved measurements. For fluorescence quenching with glucose the results of steady-state measurements fulfill Stern-Volmer equation. The quenching constants are increasing with growing pH. The decay of fluorescence is monoexponential with lifetime about 8.4 ns, which does not depend on pH and glucose concentration indicating static quenching. The quenching constant can be interpreted as apparent equilibrium constant of estrification of boronic group with diol. Quantum dots are also quenching 3-amino phenylboronic acid fluorescence. Fluorescence lifetime, in this case, is slightly decreasing with increasing concentration of quantum dots. The quenching constants are increasing slightly with pH's growth. Quenching mechanism of 3-amino phenylboronic acid fluorescence by quantum dots needs further experiments to be fully explained. Copyright © 2014 Elsevier B.V. All rights reserved.

Amino acid detection using fluoroquinolone–Cu2+ complex as a switch-on fluorescent probe by competitive complexation without derivatization

International Nuclear Information System (INIS)

Farokhcheh, Alireza; Alizadeh, Naader

2014-01-01

In this work, we describe the use of fluoroquinolone–Cu 2+ complex as a competitive switch-on fluorescence probe for amino acid determination without derivatization. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Cu 2+ ion, increases drastically by an addition of amino acid (glycine, phenylalanine, sarcosine, aspargine, alanine, proline, arginine, aspartic acid, glutamic acid, lysine, leucine and isoleucine). The overall stability constants of Cu 2+ ion complexes with amino acids were determined by fluorometric titration of fluoroquinolone-Cu 2+ complex with the amino acid solution. Furthermore, the probe shows high calibration sensitivity toward aspartic acid. The fluorescence signal depends linearly on the amino acid concentration within the range of concentration from 1.2×10 −7 to 1.1×10 −5 mol L −1 for aspartic acid. The detection limit was found 2.7×10 −8 mol L −1 with the relative standard deviation (RSD%) about 2.1% (five replicate). -- Highlights: • Amino acids are detected by using fluoroquinolone–Cu 2+ complex as fluorescent probe. • Amino acids were detected based on a competitive complexation reaction. • Probe has been able to recognize amino acids through switch-on fluorescence behavior. • Ultra-trace level of aspartic and glutamic acid is determined without derivatization

Poly-lactic acid nanoparticles (PLA-NP) promote physiological modifications in lung epithelial cells and are internalized by clathrin-coated pits and lipid rafts.

Science.gov (United States)

da Luz, Camila Macedo; Boyles, Matthew Samuel Powys; Falagan-Lotsch, Priscila; Pereira, Mariana Rodrigues; Tutumi, Henrique Rudolf; de Oliveira Santos, Eidy; Martins, Nathalia Balthazar; Himly, Martin; Sommer, Aniela; Foissner, Ilse; Duschl, Albert; Granjeiro, José Mauro; Leite, Paulo Emílio Corrêa

2017-01-31

Poly-lactic acid nanoparticles (PLA-NP) are a type of polymeric NP, frequently used as nanomedicines, which have advantages over metallic NP such as the ability to maintain therapeutic drug levels for sustained periods of time. Despite PLA-NP being considered biocompatible, data concerning alterations in cellular physiology are scarce. We conducted an extensive evaluation of PLA-NP biocompatibility in human lung epithelial A549 cells using high throughput screening and more complex methodologies. These included measurements of cytotoxicity, cell viability, immunomodulatory potential, and effects upon the cells' proteome. We used non- and green-fluorescent PLA-NP with 63 and 66 nm diameters, respectively. Cells were exposed with concentrations of 2, 20, 100 and 200 µg/mL, for 24, 48 and 72 h, in most experiments. Moreover, possible endocytic mechanisms of internalization of PLA-NP were investigated, such as those involving caveolae, lipid rafts, macropinocytosis and clathrin-coated pits. Cell viability and proliferation were not altered in response to PLA-NP. Multiplex analysis of secreted mediators revealed a low-level reduction of IL-12p70 and vascular epidermal growth factor (VEGF) in response to PLA-NP, while all other mediators assessed were unaffected. However, changes to the cells' proteome were observed in response to PLA-NP, and, additionally, the cellular stress marker miR155 was found to reduce. In dual exposures of staurosporine (STS) with PLA-NP, PLA-NP enhanced susceptibility to STS-induced cell death. Finally, PLA-NP were rapidly internalized in association with clathrin-coated pits, and, to a lesser extent, with lipid rafts. These data demonstrate that PLA-NP are internalized and, in general, tolerated by A549 cells, with no cytotoxicity and no secretion of pro-inflammatory mediators. However, PLA-NP exposure may induce modification of biological functions of A549 cells, which should be considered when designing drug delivery systems. Moreover

Adhesion dynamics of porcine esophageal fibroblasts on extracellular matrix protein-functionalized poly(lactic acid)

International Nuclear Information System (INIS)

Cai Ning; Gong Yingxue; Chan, Vincent; Liao Kin; Chian, Kerm Sin

2008-01-01

Effective attachment of esophageal cells on biomaterials is one important requirement in designing engineered esophagus substitute for esophageal cancer treatment. In this study, poly(lactic acid) (PLA) was subjected to surface modification by coupling extracellular matrix (ECM) proteins on its surface to promote cell adhesion. Two typical ECM proteins, collagen type I (COL) and fibronectin (FN), were immobilized on the PLA surface with the aid of glutaraldehyde as a cross linker between aminolyzed PLA and ECM proteins. By using confocal reflectance interference contrast microscopy (C-RICM) integrating with phase contrast microscopy, the long-term adhesion dynamics of porcine esophageal fibroblasts (PEFs) on four types of surfaces (unmodified PLA, PLA-COOH, PLA-COL and PLA-FN) was investigated during 24 h of culture. It is demonstrated by C-RICM results that PEFs form strong adhesion contact on all four types of surfaces at different stages of cell seeding. Among the four surfaces, PEFs on the PLA-FN surface reach the maximum adhesion energy (9.5 x 10 -7 J m -2 ) in the shortest time (20 min) during the initial stage of cell seeding. After adhesion energy reaches the maximum value, PEFs maintain their highly deformed geometries till they reached a steady state after 20 h of culture. F-actin immunostaining results show that the evolvement of spatial organization of F-actin is tightly correlated with the formation of adhesion contact and cell spreading. Furthermore, the cell attachment ratio of PEFs on PLA in 2 h is only 26% compared with 88% on PLA-FN, 73% on PLA-COL and 36% on PLA-COOH. All the results demonstrate the effect of surface functionalization on the biophysical responses of PEFs in cell adhesion. Fibronectin-immobilized PLA demonstrates promising potential for application as an engineered esophagus substitute

A novel turn-on fluorescent strategy for sensing ascorbic acid using graphene quantum dots as fluorescent probe.

Science.gov (United States)

Liu, Hua; Na, Weidan; Liu, Ziping; Chen, Xueqian; Su, Xingguang

2017-06-15

In this paper, a facile and rapid fluorescence turn-on assay for fluorescent detection of ascorbic acid (AA) was developed by using the orange emission graphene quantum dots (GQDs). In the presence of horse radish peroxidase (HRP) and hydrogen peroxide (H 2 O 2 ), catechol can be oxidized by hydroxyl radicals and converted to o-benzoquinone, which can significantly quench the fluorescence of GQDs. However, when AA present in the system, it can consume part of H 2 O 2 and hydroxyl radicals to inhibit the generation of o-benzoquinone, resulting in fluorescence recovery. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of H 2 O 2 in the range of 3.33-500µM with a detection limit of 1.2µM. The linear detection for AA was in the range from 1.11 to 300µM with a detection limit of 0.32µM. The proposed method was applied to the determination of AA in human serum samples with satisfactory results. Copyright © 2017. Published by Elsevier B.V.

A highly selective turn-on fluorescent probe for hypochlorous acid based on hypochlorous acid-induced oxidative intramolecular cyclization of boron dipyrromethene-hydrazone

International Nuclear Information System (INIS)

Chen, Wei-Chieh; Venkatesan, Parthiban; Wu, Shu-Pao

2015-01-01

Highlights: • A BODIPY-based fluorescent probe for sensing HOCl was developed. • The probe utilizes the HOCl-promoted cyclization in response to the amount of HOCl. • The probe might have application in the investigation of HOCl in biological systems. - Abstract: A BODIPY-based fluorescent probe, HBP, was developed for the detection of hypochlorous acid based on the specific hypochlorous acid-promoted oxidative intramolecular cyclization of heterocyclic hydrazone in response to the amount of HOCl. The reaction is accompanied by a 41-fold increase in the fluorescent quantum yield (from 0.004 to 0.164). The fluorescence intensity of the reaction between HOCl and HBP is linear in the HOCl concentration range of 1–8 μM with a detection limit of 2.4 nM (S/N = 3). Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HBP could be used as an effective fluorescent probe for detecting HOCl in living cells

A highly selective turn-on fluorescent probe for hypochlorous acid based on hypochlorous acid-induced oxidative intramolecular cyclization of boron dipyrromethene-hydrazone

Energy Technology Data Exchange (ETDEWEB)

Chen, Wei-Chieh; Venkatesan, Parthiban; Wu, Shu-Pao, E-mail: spwu@mail.nctu.edu.tw

2015-07-02

Highlights: • A BODIPY-based fluorescent probe for sensing HOCl was developed. • The probe utilizes the HOCl-promoted cyclization in response to the amount of HOCl. • The probe might have application in the investigation of HOCl in biological systems. - Abstract: A BODIPY-based fluorescent probe, HBP, was developed for the detection of hypochlorous acid based on the specific hypochlorous acid-promoted oxidative intramolecular cyclization of heterocyclic hydrazone in response to the amount of HOCl. The reaction is accompanied by a 41-fold increase in the fluorescent quantum yield (from 0.004 to 0.164). The fluorescence intensity of the reaction between HOCl and HBP is linear in the HOCl concentration range of 1–8 μM with a detection limit of 2.4 nM (S/N = 3). Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HBP could be used as an effective fluorescent probe for detecting HOCl in living cells.

DOPO-Modified Two-Dimensional Co-Based Metal-Organic Framework: Preparation and Application for Enhancing Fire Safety of Poly(lactic acid).

Science.gov (United States)

Hou, Yanbei; Liu, Longxiang; Qiu, Shuilai; Zhou, Xia; Gui, Zhou; Hu, Yuan

2018-03-07

Co-based metal-organic framework (Co-MOF) nanosheets were successfully synthesized by the organic ligands with Schiff base structure. The laminated structure gives Co-MOF nanosheets a great advantage in the application in the flame retardant field. Meanwhile, -C═N- from Schiff base potentially provides active sites for further modification. In this work, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was used to modify Co-MOF (DOPO@Co-MOF) to further enhance its flame retardant efficiency. It is attractive that DOPO has a synergistic effect with Co-MOF on improving fire safety of poly(lactic acid) (PLA). The obvious decrease in the values of peak heat release (27%), peak smoke production (56%), and total CO yield (20%) confirmed the enhanced fire safety of PLA composites. The possible flame retardant mechanism was proposed based on characterization results. Moreover, the addition of DOPO@Co-MOF had a positive influence on the mechanical performance, including tensile properties and impact resistance. This work designed and synthesized two-dimensional MOFs with active groups. As-prepared Co-MOF with expected structure shows a novel direction of preparing MOFs for flame retardant application.

Bis-Pyrene-Modified Unlocked Nucleic Acids: Synthesis, Hybridization Studies, and Fluorescent Properties

Czech Academy of Sciences Publication Activity Database

Perlíková, Pavla; Ejlersen, M.; Langkjaer, N.; Wengel, J.

2014-01-01

Roč. 9, č. 9 (2014), s. 2120-2127 ISSN 1860-7179 Grant - others:European Research Council(XE) FP7-268776 Institutional support: RVO:61388963 Keywords : fluorescence * nucleic acid hybridization * oligonucleotides * pyrenes * unlocked nucleic acids Subject RIV: CC - Organic Chemistry Impact factor: 2.968, year: 2014

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-03-30

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

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

International Nuclear Information System (INIS)

Gartner, Hunter; Li, Yana; Almenar, Eva

2015-01-01

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

Exciton-controlled fluorescence: application to hybridization-sensitive fluorescent DNA probe.

Science.gov (United States)

Okamoto, Akimitsu; Ikeda, Shuji; Kubota, Takeshi; Yuki, Mizue; Yanagisawa, Hiroyuki

2009-01-01

A hybridization-sensitive fluorescent probe has been designed for nucleic acid detection, using the concept of fluorescence quenching caused by the intramolecular excitonic interaction of fluorescence dyes. We synthesized a doubly thiazole orange-labeled nucleotide showing high fluorescence intensity for a hybrid with the target nucleic acid and effective quenching for the single-stranded state. This exciton-controlled fluorescent probe was applied to living HeLa cells using microinjection to visualize intracellular mRNA localization. Immediately after injection of the probe into the cell, fluorescence was observed from the probe hybridizing with the target RNA. This fluorescence rapidly decreased upon addition of a competitor DNA. Multicoloring of this probe resulted in the simple simultaneous detection of plural target nucleic acid sequences. This probe realized a large, rapid, reversible change in fluorescence intensity in sensitive response to the amount of target nucleic acid, and facilitated spatiotemporal monitoring of the behavior of intracellular RNA.

Response of Substituted Indoleacetic Acids in the Indolo-alpha-pyrone Fluorescence Determination

DEFF Research Database (Denmark)

Engvild, Kjeld Christensen; Böttger, M.; Kaiser, P.

1978-01-01

.-pyrones. Other halogenated indoleacetic acids show between zero and 60% of the fluorescence of IAA. Apparently the concentration of IAA cannot be determined in crude extracts in the presence of 4-chloro- or 5-hydroxy-indoleacetic acid, because separate determinations of each of these compounds are not possible...

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-03-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-03-01

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

Reinforcement effect of poly(butylene succinate) (PBS)-grafted cellulose nanocrystal on toughened PBS/polylactic acid blends.

Science.gov (United States)

Zhang, Xuzhen; Zhang, Yong

2016-04-20

Poly(butylene succinate) (PBS)/polylactic acid (PLA) blends modified with dicumyl peroxide (DCP) were reinforced by PBS-g-cellulose nanocrystal (CNC) through melt mixing. PBS-g-CNC was prepared through in situ polymerization and its structure was confirmed by FTIR, (13)C NMR, XPS and GPC analysis after saponification. The morphological analysis of PBS/PLA/PBS-g-CNC composites before and after etched by CH2Cl2 shows that the addition of DCP and PBS-g-CNC could decrease the size of PBS as a dispersed phase in PLA matrix and improve the dispersion of PBS-g-CNC in both PBS and PLA phases, which could affect the crystallization and mechanical properties of composites. The crystallinity of PLA α'-phase crystal in PBS/PLA/PBS-g-CNC composites is increased obviously by the addition of PBS-g-CNC, leading to an increase of the crystallinity of the composites. PBS/PLA blends modified by DCP have high Notched Izod impact strength and moduli, and the values are increased by the addition of PBS-g-CNC. Both storage modulus and glass translation temperature of PBS/PLA blend are increased by DCP and PBS-g-CNC, which is proved by DMA results, showing a weak molecular segment mobility of PBS/PLA matrix. The addition of DCP decreases the crystallization temperature and crystallinity of PBS/PLA composite, but increases the thermal stability of composites, mostly because of the crosslink effect of DCP on PBS/PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of organoclay to miscibility, mechanical and thermal properties of poly(lactic acid) and propylene-ethylene copolymer blends

Science.gov (United States)

Wacharawichanant, S.; Ounyai, C.; Rassamee, P.

2017-07-01

The effects of propylene-ethylene copolymer (PEC or PEC3300) and clay surface modified with 25-30 wt% of trimethylstearyl ammonium (Clay-TSA) on morphology, thermal and mechanical properties of poly(lactic acid) (PLA) were investigated. The morphology analysis showed PLA/PEC3300 blends clearly demonstrated a two-phase separation of dispersed phase and the matrix phase and the addition of Clay-TSA could improve the miscibility of PLA and PEC3300 blends due to the decreased of the domain sizes of dispersed PEC3300 phase in the polymer matrix. From X-ray diffraction analysis showed the intercalation of PLA chains inside the Clay-TSA and this result implied that Clay-TSA platelets acted as an effective compatibilizer. The tensile properties showed the strain at break of PLA was improved after adding PEC3300 while Young’s modulus, tensile strength and storage modulus decreased. The addition of Clay-TSA could improve Young’s modulus of PLA/PEC3300 blends. The addition of Clay-TSA 7 phr showed the maximum of Young’s modulus of PLA/PEC3300/Clay-TSA composites. The thermal properties found that the addition of PEC3300 and Clay-TSA did not change significantly on the glass transition temperature and melting point temperature of PLA. The percent of crystallinity of PLA decreased with increasing PEC content. The thermal stability of PLA improved after adding PEC3300.

Fluorescence Behavior and Dural Infiltration of Meningioma Analyzed by 5-Aminolevulinic Acid-Based Fluorescence: Operating Microscope Versus Mini-Spectrometer.

Science.gov (United States)

Knipps, Johannes; Beseoglu, Kerim; Kamp, Marcel; Fischer, Igor; Felsberg, Joerg; Neumann, Lisa M; Steiger, Hans-Jakob; Cornelius, Jan F

2017-12-01

To compare fluorescence intensity of tumor specimens, as measured by a fluorescence-guided surgery microscope and a spectrometer, to evaluate tumor infiltration of dura mater around meningiomas with help of these 2 different 5-aminolevulinic acid (5-ALA)-based fluorescence tools, and to correlate fluorescence intensity with histopathologic data. In a clinical series, meningiomas were resected by 5-ALA fluorescence-guided surgery. Fluorescence intensity was semiquantitatively rated by the surgeon at predefined points. Biopsies were harvested and fluorescence intensity measured by a spectrometer and histopathologically analyzed. Sampling was realized at the level of the dura in a centrifugal direction. A total of 104 biopsies (n = 13 tumors) were analyzed. Specificity and sensitivity of the microscope were 0.96 and 0.53 and of the spectrometer 0.95 and 0.93, respectively. Fluorescence intensity as measured by the spectrometer was correlated to histologically confirmed tumor burden. In a centrifugal direction, tumor burden and fluorescence intensity continuously decreased (along the dural tail). Below a threshold value of 639 arbitrary units no tumor was histologically detectable. At the level of the dura the spectrometer was highly sensitive for detection of meningioma cells. The surgical microscope showed false negative results and missed residual tumor cells in more than one half of the cases. The complementary use of both fluorescence tools may improve resection quality. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimization of Processing Parameters in 3D-Printing of Poly(lactic acid by Fused Deposition Modeling Method

Directory of Open Access Journals (Sweden)

Maryam Ezoji

2017-05-01

Full Text Available Nowadays, making use of additive manufacturing (AM processes such as fused deposition modeling (FDM, in different areas, such as car manufacturing, biomedical and aerospace industries is gaining popularity worldwide because of their capacities in producing functional parts with complex geometries. Therefore, it is very important to identify the significance of FDM processing parameters which would have an impact on the quality of articles produced by the processing system. In this work, poly(lactic acid was used to study the effects of processing parameters such as layer thickness, raster angle and printing plane on the tensile properties and surface roughness of the printed specimens. The results showed that the tensile strength of a specimen increased by reducing its layer thickness. However, the elastic modulus values increased with decreasing the layer thickness to some extent. Moreover, when the layer thickness was kept constant at 0.05 mm and 3D-printing was carried out in XYZ plane, the maximum modulus and tensile strength were obtained for the raster angle of 0˚. Microscopic studies showed that in low layer thickness, the polymeric layers diffused properly into each other and no voids were formed between the layers. However, with a thickness above its critical value, a few voids were formed between the layers which played as a stress concentrator and decreased the tensile strength of the specimens. The results also showed that the surface roughness increased with increasing the layer thickness.

Development of a facile and sensitive HPLC-FLD method via fluorescence labeling for triterpenic acid bioavailability investigation.

Science.gov (United States)

You, Jinmao; Wu, Di; Zhao, Mei; Li, Guoliang; Gong, Peiwei; Wu, Yueyue; Guo, Yu; Chen, Guang; Zhao, Xianen; Sun, Zhiwei; Xia, Lian; Wu, Yongning

2017-06-01

Triterpenic acids are widely distributed in many fruits and are known for their medicinal benefits. The study of bioavailability has been an important task for a better understanding of the triterpenic acids. Although many methods based on fluorescence labeling for triterpenic acid determination have been established, these reported methods needed anhydrous conditions, which are not suitable for the convenient study of triterpenic acid bioavailability. Inspired by that, a versatile method, which overcomes the difficulty of the reported methods, has been first developed in this study. The novel method using 2-[12-benzo[b]acridin-5- (12H)-yl]-acetohydrazide (BAAH) as the fluorescence labeling reagent coupled with high-performance liquid chromatography with fluorescence detection was first developed for the study of triterpenic acid bioavailability. Furthermore, the labeling conditions have been optimized in order to achieve the best fluorescence labeling yield. Under the optimal conditions, the quantitative linear range of analytes was 2-1000 ng mL -1 , and the correlation coefficients were >0.9998. The detection limits for all triterpenic acid derivatives were achieved within the range of 0.28-0.29 ng mL -1 . The proposed method was successfully applied to the study of triterpenic acid bioavailability with excellent applicability and good reproducibility. Copyright © 2016 John Wiley & Sons, Ltd.

Amino acid detection using fluoroquinolone–Cu{sup 2+} complex as a switch-on fluorescent probe by competitive complexation without derivatization

Energy Technology Data Exchange (ETDEWEB)

Farokhcheh, Alireza; Alizadeh, Naader, E-mail: alizaden@modares.ac.ir

2014-01-15

In this work, we describe the use of fluoroquinolone–Cu{sup 2+} complex as a competitive switch-on fluorescence probe for amino acid determination without derivatization. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Cu{sup 2+} ion, increases drastically by an addition of amino acid (glycine, phenylalanine, sarcosine, aspargine, alanine, proline, arginine, aspartic acid, glutamic acid, lysine, leucine and isoleucine). The overall stability constants of Cu{sup 2+} ion complexes with amino acids were determined by fluorometric titration of fluoroquinolone-Cu{sup 2+} complex with the amino acid solution. Furthermore, the probe shows high calibration sensitivity toward aspartic acid. The fluorescence signal depends linearly on the amino acid concentration within the range of concentration from 1.2×10{sup −7} to 1.1×10{sup −5} mol L{sup −1} for aspartic acid. The detection limit was found 2.7×10{sup −8} mol L{sup −1} with the relative standard deviation (RSD%) about 2.1% (five replicate). -- Highlights: • Amino acids are detected by using fluoroquinolone–Cu{sup 2+} complex as fluorescent probe. • Amino acids were detected based on a competitive complexation reaction. • Probe has been able to recognize amino acids through switch-on fluorescence behavior. • Ultra-trace level of aspartic and glutamic acid is determined without derivatization.

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

Science.gov (United States)

Chen, Xi; Li, Yan; Gu, Ning

2010-08-01

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

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

International Nuclear Information System (INIS)

Chen Xi; Li Yan; Gu Ning

2010-01-01

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

Multiplexed Detection of Attomoles of Nucleic Acids Using Fluorescent Nanoparticle Counting Platform.

Science.gov (United States)

Pei, Xiaojing; Yin, Haoyan; Lai, Tiancheng; Zhang, Junlong; Liu, Feng; Xu, Xiao; Li, Na

2018-01-16

The sensitive multiplexed detection of nucleic acids in a single sample by a simple manner is of pivotal importance for the diagnosis and therapy of human diseases. Herein, we constructed an automatic fluorescent nanoparticle (FNP) counting platform with a common fluorescence microscopic imaging setup for nonamplification multiplexed detection of attomoles of nucleic acids. Taking the advantages of the highly bright, multicolor emitting FNPs and magnetic separation, the platform enables sensitive multiplexed detection without the need for extra fluorescent labels. Quantification for multiplex DNAs, multiplex microRNAs (miRNA), as well as a DNA and miRNA mixture was achieved with a similar dynamic range, a limit of detection down to 5 amol (5 μL detection volume), and a 81-115% spike recovery from different biological sample matrices. In particular, the sensitivity for multiplex miRNA is by far among the highest without using amplification or the lock nucleic acid hybridization enhancement strategy. Results regarding miRNA-141 from four different cell lines were agreeable with those of the quantitative reverse transcription polymerase chain reaction. Simultaneous detection of miRNA-141 and miRNA-21 in four different cell lines yielded consistent results with publications, indicating the potential for monitoring multiplex miRNA expression associated with the collaborative regulation of important cellular events. This work expands the rule set of multiplex nucleic acid detection strategies and shows promising potential application in clinical diagnosis.

Novel (Phenylethynyl)pyrene-LNA Constructs for Fluorescence SNP Sensing in Polymorphic Nucleic Acid Targets

DEFF Research Database (Denmark)

Astakhova, Irina Kira; Samokhina, Evgeniya; Babu, B Ravindra

2012-01-01

We describe fluorescent oligonucleotide probes labeled with novel (phenylethynyl)pyrene dyes attached to locked nucleic acids. Furthermore, we prove the utility of these probes for the effective detection of single-nucleotide polymorphisms in natural nucleic acids. High-affinity hybridization......DNA and RNA gene fragments. Target sequences were obtained by analysis of 200 clinical samples from patients currently receiving anti-HIV/AIDS combination therapy at the Russian Federal AIDS Center. Using these fluorescent oligonucleotides, we were able to detect the target mutation despite all the challenges...

Fluorescence quenching of uric acid solubilized in bicontinuous microemulsion by nitrobenzene

Directory of Open Access Journals (Sweden)

Maurice O. Iwunze

2013-02-01

Full Text Available Abstract: Uric Acid is known to be practically insoluble in aqueous and alcoholic media. However, it exhibits a reasonable solubility in a Bicontinuous Microemulsion system – a 15-fold or more increase in solubility in this system compared to its solubility in water. The bicontinuous microemulsion is made up of three components –Dodecane-Surfactant-water. Uric acid solubilized in this system is quenched by nitrobenzene. The obtained fluorescence data do not obey the Stern-Volmer equation when plotted accordingly. Therefore, the modified Stern-Volmer equation was used to analyze the data. It was observed that only one third (1/3 of uric acid is accessible to quenching in this medium and the reaction is diffusion-limited. The Stern-Volmer quenching constant, KSV, was calculated to be 130 M-1 and the fluorescence lifetime, 0, the quantum yield,, and the bimolecular quenching rate constant, kq, were calculated as 10.6 nanoseconds, 0.06 and 1.231010 M-1s-1, respectively.

[Study of Reaction Dynamics between Bovine Serum Albumin and Folic Acid by Stopped-Flow/Fluorescence].

Science.gov (United States)

Ye, San-xian; Luo, Yun-jing; Qiao, Shu-liang; Li, Li; Liu, Cai-hong; Shi, Jian-long; An, Xue-jing

2016-01-01

As a kind of coenzyme of one-carbon enzymes in vivo, folic acid belongs to B vitamins, which can interact with other vitamins and has great significance for converting among amino acids, dividing growth of cells and protein synthesis reactions. Half-life, concentration and reaction rate constant of drugs are important parameters in pharmacokinetic study. In this paper, by utilizing fluorescence spectrophotometer and stopped-flow spectrum analyzer, reaction kinetic parameters between bovine serum albumin(BSA) and folic acid in a bionic system have been investigated, which provide references for parameters of drug metabolism related to folic acid. By using Stern-Volmer equation dealing with fluorescence quenching experiments data, we concluded that under 25, 30, and 37 degrees C, the static quenching constants of folic acid to intrinsic fluorescence from bovine serum albumin were 2.455 x 10(10), 4.900 x 10(10) and 6.427 x 10(10) L x mol(-1) x s(-1) respectively; The results of kinetic reaction rate have shown that the reaction rate of BSA and folic acid are greater than 100 mol x L(-1) x s(-1) at different temperatures, pH and buffering media, illustrating that the quenching mechanism between BSA and folic acid is to form composite static quenching process. Reaction concentration of bovine serum albumin and its initial concentration were equal to the secondary reaction formula, and the correlation coefficient was 0.998 7, while the half-life (t1/2) was 0.059 s at physiological temperature. With the increase of folic acid concentration, the apparent rate constant of this reaction had a linear increasing trend, the BSA fluorescence quenching rate constant catalyzed by folic acid was 3.174 x 10(5) mol x L(-1) x s(-1). Furthermore, with different buffer, the apparent rate constant and reaction rate constant of BSA interacting with folic acid were detected to explore the influence on the reaction under physiological medium, which is of great significance to determine the

Experimental Evolution of a Green Fluorescent Protein Composed of 19 Unique Amino Acids without Tryptophan

Science.gov (United States)

Kawahara-Kobayashi, Akio; Hitotsuyanagi, Mitsuhiro; Amikura, Kazuaki; Kiga, Daisuke

2014-04-01

At some stage of evolution, genes of organisms may have encoded proteins that were synthesized using fewer than 20 unique amino acids. Similar to evolution of the natural 19-amino-acid proteins GroEL/ES, proteins composed of 19 unique amino acids would have been able to evolve by accumulating beneficial mutations within the 19-amino-acid repertoire encoded in an ancestral genetic code. Because Trp is thought to be the last amino acid included in the canonical 20-amino-acid repertoire, this late stage of protein evolution could be mimicked by experimental evolution of 19-amino-acid proteins without tryptophan (Trp). To further understand the evolution of proteins, we tried to mimic the evolution of a 19-amino-acid protein involving the accumulation of beneficial mutations using directed evolution by random mutagenesis on the whole targeted gene sequence. We created active 19-amino-acid green fluorescent proteins (GFPs) without Trp from a poorly fluorescent 19-amino-acid mutant, S1-W57F, by using directed evolution with two rounds of mutagenesis and selection. The N105I and S205T mutations showed beneficial effects on the S1-W57F mutant. When these two mutations were combined on S1-W57F, we observed an additive effect on the fluorescence intensity. In contrast, these mutations showed no clear improvement individually or in combination on GFPS1, which is the parental GFP mutant composed of 20 amino acids. Our results provide an additional example for the experimental evolution of 19-amino-acid proteins without Trp, and would help understand the mechanisms underlying the evolution of 19-amino-acid proteins. (236 words)

Sensitive detection of nucleic acids by PNA hybridization directed co-localization of fluorescent beads

DEFF Research Database (Denmark)

Shiraishi, Takehiko; Deborggraeve, Stijn; Büscher, Philippe

2011-01-01

)avidin-coated fluorescent beads, differing in size and color [green beads (1 µm) and red beads (5.9 µm)], thereby allowing distinct detection of each PNA probe by conventional fluorescence microscopy. These two PNA beads showed easily detectable co-localization when simultaneously hybridizing to a target nucleic acid...

New fluorescent bile acids: synthesis, chemical characterization, and disastereoselective uptake by Caco-2 cells of 3-deoxy 3-NBD-amino deoxycholic and ursodeoxycholic acid.

Science.gov (United States)

Májer, Ferenc; Salomon, Johanna J; Sharma, Ruchika; Etzbach, Simona V; Najib, Mohd Nadzri Mohd; Keaveny, Ray; Long, Aideen; Wang, Jun; Ehrhardt, Carsten; Gilmer, John F

2012-03-01

Deoxycholic acid (DCA), a secondary bile acid (BA), and ursodeoxycholic acid (UDCA), a tertiary BA, cause opposing effects in vivo and in cell suspensions. Fluorescent analogues of DCA and UDCA could help investigate important questions about their cellular interactions and distribution. We have prepared a set of isomeric 3α- and 3β-amino analogues of UDCA and DCA and derivatised these with the discrete fluorophore, 4-nitrobenzo-2-oxa-1,3-diazol (NBD), forming the corresponding four fluorescent adducts. These absorb in the range 465-470 nm and fluoresce at approx. 535 nm. In order to determine the ability of the new fluorescent bile acids to mimic the parents, their uptake was studied using monolayers of Caco-2 cells, which are known to express multiple proteins of the organic anion-transporting peptide (OATP) subfamily of transporters. Cellular uptake was monitored over time at 4 and 37°C to distinguish between passive and active transport. All four BA analogues were taken up but in a strikingly stereo- and structure-specific manner, suggesting highly discriminatory interactions with transporter protein(s). The α-analogues of DCA and to a lesser extent UDCA were actively transported, whereas the β-analogues were not. The active transport process was saturable, with Michaelis-Menten constants for 3α-NBD DCA (5) being K(m)=42.27±12.98 μM and V(max)=2.8 ± 0.4 nmol/(mg protein*min) and for 3α-NBD UDCA (3) K(m)=28.20 ± 7.45 μM and V(max)=1.8 ± 0.2 nmol/(mg protein*min). These fluorescent bile acids are promising agents for investigating questions of bile acid biology and for detection of bile acids and related organic anion transport processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Degradability Enhancement of Poly(Lactic Acid by Stearate-Zn₃Al LDH Nanolayers

Directory of Open Access Journals (Sweden)

Mahboobeh Eili

2012-06-01

Full Text Available 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.

Comparative study of the fatty acid binding process of a new FABP from Cherax quadricarinatus by fluorescence intensity, lifetime and anisotropy.

Directory of Open Access Journals (Sweden)

Jiayao Li

Full Text Available Fatty acid-binding proteins (FABPs are small cytosolic proteins, largely distributed in invertebrates and vertebrates, which accomplish uptake and intracellular transport of hydrophobic ligands such as fatty acids. Although long chain fatty acids play multiple crucial roles in cellular functions (structural, energy metabolism, regulation of gene expression, the precise functions of FABPs, especially those of invertebrate species, remain elusive. Here, we have identified and characterized a novel FABP family member, Cq-FABP, from the hepatopancreas of red claw crayfish Cherax quadricarinatus. We report the characterization of fatty acid-binding affinity of Cq-FABP by four different competitive fluorescence-based assays. In the two first approaches, the fluorescent probe 8-Anilino-1-naphthalenesulfonate (ANS, a binder of internal cavities of protein, was used either by directly monitoring its fluorescence emission or by monitoring the fluorescence resonance energy transfer occurring between the single tryptophan residue of Cq-FABP and ANS. The third and the fourth approaches were based on the measurement of the fluorescence emission intensity of the naturally fluorescent cis-parinaric acid probe or the steady-state fluorescence anisotropy measurements of a fluorescently labeled fatty acid (BODIPY-C16, respectively. The four methodologies displayed consistent equilibrium constants for a given fatty acid but were not equivalent in terms of analysis. Indeed, the two first methods were complicated by the existence of non specific binding modes of ANS while BODIPY-C16 and cis-parinaric acid specifically targeted the fatty acid binding site. We found a relationship between the affinity and the length of the carbon chain, with the highest affinity obtained for the shortest fatty acid, suggesting that steric effects primarily influence the interaction of fatty acids in the binding cavity of Cq-FABP. Moreover, our results show that the binding affinities

Single-Labeled Oligonucleotides Showing Fluorescence Changes upon Hybridization with Target Nucleic Acids

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Gil Tae Hwang

2018-01-01

Full Text Available Sequence-specific detection of nucleic acids has been intensively studied in the field of molecular diagnostics. In particular, the detection and analysis of single-nucleotide polymorphisms (SNPs is crucial for the identification of disease-causing genes and diagnosis of diseases. Sequence-specific hybridization probes, such as molecular beacons bearing the fluorophore and quencher at both ends of the stem, have been developed to enable DNA mutation detection. Interestingly, DNA mutations can be detected using fluorescently labeled oligonucleotide probes with only one fluorophore. This review summarizes recent research on single-labeled oligonucleotide probes that exhibit fluorescence changes after encountering target nucleic acids, such as guanine-quenching probes, cyanine-containing probes, probes containing a fluorophore-labeled base, and microenvironment-sensitive probes.

Films Based on Poly(lactic acid Biopolymer: Effect of Clay and Cellulosic Nanoparticles on their Physical, Mechanical and Structural Properties

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Saeed Dadashi

2012-12-01

Full Text Available Physical, mechanical and structural properties of poly(lactic acid (PLA-basedfilms containing different amounts of nanoclay and cellulose prepared bysolvent casting method were examined. Physical properties including thickness,transparency and color did not change significantly with addition of nanoparticles to the polymer matrix. X-Ray diffraction (XRD patterns showed that pure PLA has a semi-crystalline structure and addition of nanoclay into this polymer would produce more regular structure which results in improved crystallization. It also showed that the peak is shifted to lower degrees, with greater interlayer distance of nanoclay giving an intercalated structure. Because of the nature and particle size of the MCC, it did not interact sufficiently with the polymer. Tensile strength, elastic modulus andelongation-at-break of neat PLA were 27.44 MPa, 1.84 GPa and 24.53% which with the addition of 7% of nanoclay, was changed to 40.34, 2.62 and 10.36°C, respectively. As the results of XRD, MCC were indications of no significant effect on mechanical properties, AFM images were used to evaluate the surface morphology and roughness of PLA films. Neat PLA had smoother surfaces and a lower roughness parameter (Sa. This study indicates that PLA has acceptable properties which could be used forpackaging and other applications.

Polylactic acid nano- and microchamber arrays for encapsulation of small hydrophilic molecules featuring drug release via high intensity focused ultrasound.

Science.gov (United States)

Gai, Meiyu; Frueh, Johannes; Tao, Tianyi; Petrov, Arseniy V; Petrov, Vladimir V; Shesterikov, Evgeniy V; Tverdokhlebov, Sergei I; Sukhorukov, Gleb B

2017-06-01

Long term encapsulation combined with spatiotemporal release for a precisely defined quantity of small hydrophilic molecules on demand remains a challenge in various fields ranging from medical drug delivery, controlled release of catalysts to industrial anti-corrosion systems. Free-standing individually sealed polylactic acid (PLA) nano- and microchamber arrays were produced by one-step dip-coating a PDMS stamp into PLA solution for 5 s followed by drying under ambient conditions. The wall thickness of these hydrophobic nano-microchambers is tunable from 150 nm to 7 μm by varying the PLA solution concentration. Furthermore, small hydrophilic molecules were successfully in situ precipitated within individual microchambers in the course of solvent evaporation after sonicating the PLA@PDMS stamp to remove air-bubbles and to load the active substance containing solvent. The cargo capacity of single chambers was determined to be in the range of several picograms, while it amounts to several micrograms per cm 2 . Two different methods for sealing chambers were compared: microcontact printing versus dip-coating whereby microcontact printing onto a flat PLA sheet allows for entrapment of micro-air-bubbles enabling microchambers with both ultrasound responsiveness and reduced permeability. Cargo release triggered by external high intensity focused ultrasound (HIFU) stimuli is demonstrated by experiment and compared with numerical simulations.

Sensitive detection of strong acidic condition by a novel rhodamine-based fluorescent pH chemosensor.

Science.gov (United States)

Tan, Jia-Lian; Yang, Ting-Ting; Liu, Yu; Zhang, Xue; Cheng, Shu-Jin; Zuo, Hua; He, Huawei

2016-05-01

A novel rhodamine-based fluorescent pH probe responding to extremely low pH values has been synthesized and characterized. This probe showed an excellent photophysical response to pH on the basis that the colorless spirocyclic structure under basic conditions opened to a colored and highly fluorescent form under extreme acidity. The quantitative relationship between fluorescence intensity and pH value (1.75-2.62) was consistent with the equilibrium equation pH = pKa + log[(Imax - I)/(I - Imin)]. This sensitive pH probe was also characterized with good reversibility and no interaction with interfering metal ions, and was successfully applied to image Escherichia coli under strong acidity. Copyright © 2015 John Wiley & Sons, Ltd.

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

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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.

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

International Nuclear Information System (INIS)

Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Jacques, Brianna R.; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

2013-01-01

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

Evaluation of acridine orange, LysoTracker Red, and quinacrine as fluorescent probes for long-term tracking of acidic vesicles.

Science.gov (United States)

Pierzyńska-Mach, Agnieszka; Janowski, Paweł A; Dobrucki, Jurek W

2014-08-01

Acidic vesicles can be imaged and tracked in live cells after staining with several low molecular weight fluorescent probes, or with fluorescently labeled proteins. Three fluorescent dyes, acridine orange, LysoTracker Red DND-99, and quinacrine, were evaluated as acidic vesicle tracers for confocal fluorescence imaging and quantitative analysis. The stability of fluorescent signals, achievable image contrast, and phototoxicity were taken into consideration. The three tested tracers exhibit different advantages and pose different problems in imaging experiments. Acridine orange makes it possible to distinguish acidic vesicles with different internal pH but is fairly phototoxic and can cause spectacular bursts of the dye-loaded vesicles. LysoTracker Red is less phototoxic but its rapid photobleaching limits the range of useful applications considerably. We demonstrate that quinacrine is most suitable for long-term imaging when a high number of frames is required. This capacity made it possible to trace acidic vesicles for several hours, during a process of drug-induced apoptosis. An ability to record the behavior of acidic vesicles over such long periods opens a possibility to study processes like autophagy or long-term effects of drugs on endocytosis and exocytosis. © 2014 International Society for Advancement of Cytometry.

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

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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.

A Patient-Specific Polylactic Acid Bolus Made by a 3D Printer for Breast Cancer Radiation Therapy.

Science.gov (United States)

Park, So-Yeon; Choi, Chang Heon; Park, Jong Min; Chun, MinSoo; Han, Ji Hye; Kim, Jung-In

2016-01-01

The aim of this study was to assess the feasibility and advantages of a patient-specific breast bolus made using a 3D printer technique. We used the anthropomorphic female phantom with breast attachments, which volumes are 200, 300, 400, 500 and 650 cc. We simulated the treatment for a right breast patient using parallel opposed tangential fields. Treatment plans were used to investigate the effect of unwanted air gaps under bolus on the dose distribution of the whole breast. The commercial Super-Flex bolus and 3D-printed polylactic acid (PLA) bolus were applied to investigate the skin dose of the breast with the MOSFET measurement. Two boluses of 3 and 5 mm thicknesses were selected. There was a good agreement between the dose distribution for a virtual bolus generated by the TPS and PLA bolus. The difference in dose distribution between the virtual bolus and Super-Flex bolus was significant within the bolus and breast due to unwanted air gaps. The average differences between calculated and measured doses in a 200 and 300 cc with PLA bolus were not significant, which were -0.7% and -0.6% for 3mm, and -1.1% and -1.1% for 5 mm, respectively. With the Super-Flex bolus, however, significant dose differences were observed (-5.1% and -3.2% for 3mm, and -6.3% and -4.2% for 5 mm). The 3D-printed solid bolus can reduce the uncertainty of the daily setup and help to overcome the dose discrepancy by unwanted air gaps in the breast cancer radiation therapy.

Synthesis and characterization of Cerium-doped hydroxyapatite/polylactic acid composite coatings on metal substrates

Energy Technology Data Exchange (ETDEWEB)

Yuan, Qiuhua, E-mail: yuanqiuh@szu.edu.cn; Qin, Caoping; Wu, Jianbo; Xu, Anping; Zhang, Ziqiang; Liao, Junquan; Lin, Songxin; Ren, Xiangzhong; Zhang, Peixin

2016-10-01

Ce-doped hydroxyapatite/polylactic acid (HA/PLA) composites serving as implant coatings have rarely been studied by other researchers in recent years. This paper was focused to study the existence of Ce ions in structure, chemical composition and surface morphology of HA and its composite coatings. Ce-doped HA powders were synthesized by chemical precipitation method with different Ce molar fractions (0(pure HA), 0.5 mol%, 1 mol% and 2 mol%). And Ce-doped HA/PLA composite coatings were fabricated for the first time on stainless steel substrates by spin coating technique. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) coupled with energy dispersive X-ray detector (EDX), thermo gravimetric-differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS). The results showed that Ce ions were doped into the crystal lattice of apatite successfully. The (Ce + Ca)/P atomic ratios in the doped HA/PLA samples ranged from 1.614 to 1.673, which were very close to the theoretical value of 1.67 for the stoichiometric HA. The addition of PLA could keep metal substrates from catalyzing the decomposition of HA. TG-DTA analysis indicated that Ce-doped HA powder had high thermal stability, and the SEM micrographs revealed that the surface topography of Ce-doped HA/PLA composite coatings was uniform and dense when the Ce molar fraction was 2 mol%. XPS results indicated that the Ce ions doped in HA showed mixed valences of Ce{sup 3+} and Ce{sup 4+}. - Highlights: • Ce-doped HA composite coatings were synthesized by spin-coating technique for the first time. • Ce ions were demonstrated to dope into HA crystal lattice successfully. • The addition of PLA could keep metal substrates from catalyzing the decomposition of HA. • XPS results showed that Ce ions doped in HA have mixed valences of Ce{sup 3+} and Ce{sup 4+}.

Polylactic Acid Improves the Rheological Properties, and Promotes the Degradation of Sodium Carboxymethyl Cellulose-Modified Alkali-Activated Cement

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Huijing Tan

2016-10-01

Full Text Available In consideration of the insolubility in water, sensitivity to heat and wide application in the oil and gas industry as a degradable additive, this paper introduces polylactic acid (PLA to a self-degradable temporary sealing material (SDTSM to investigate its effect on the SDTSM performance and evaluate its potential to improve the rheological properties and further promote the self-degradation of the material. The thermal degradation of PLA, the rheological properties, compressive strength, hydrated products and water absorption of SDTSMs with different PLA dosages were tested. The analysis showed that the addition of 2% PLA increased the fluidity by 13.18% and reduced the plastic viscosity by 38.04%, when compared to those of the SDTSM without PLA. PLA increased the water absorption of 200 °C-heated SDTSM and had small effect on the types but decreased the hydrate products of 85 °C-cured SDTSM, and created plenty of pores in 200 °C-heated SDTSM. PLA enhanced the self-degradation level of SDTSM by generating a large amount of pores in cement. These pores worked in two ways: one was such a large amount of pores led to a looser microstructure; the other was these pores made the water impregnate the cement more easily, and then made the dissolution of substances in the 200 °C-heated SDTSM progress faster to generate heat and to destruct the microstructure.

Polyaspartamide-Polylactide Graft Copolymers with Tunable Properties for the Realization of Fluorescent Nanoparticles for Imaging.

Science.gov (United States)

Craparo, Emanuela Fabiola; Porsio, Barbara; Mauro, Nicolò; Giammona, Gaetano; Cavallaro, Gennara

2015-08-01

Here, the synthesis and the characterization of novel amphiphilic graft copolymers with tunable properties, useful in obtaining polymeric fluorescent nanoparticles for application in imaging, are described. These copolymers are obtained by chemical conjugation of rhodamine B (RhB) moieties, polylactic acid (PLA), and O-(2-aminoethyl)-O'-methyl poly(ethylene glycol) (PEG) on α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). In particular, PHEA is first functionalized with RhB to obtain PHEA-RhB with a derivatization degree in RhB (DDRhB ) equal to 0.55 mol%. By varying the reaction conditions, different amounts of PLA are grafted on PHEA-RhB to obtain PHEA-RhB-PLA with DDPLA equal to 1.9, 4.0, and 6.2 mol%. Then, PEG chains are grafted on PHEA-RhB-PLA derivatives to obtain PHEA-RhB-PLA-PEG graft copolymers. The preparation of polymeric fluorescent nanoparticles with tunable properties and spherical shape is described by using PHEA-RhB-PLA-PEG with DD in PLA and PEG equal to 4.0 and 4.9 mol%, by following easily scaling up processes, such as emulsion-solvent evaporation and high pressure homogenization (HPH)-solvent evaporation techniques. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of surface modification of glass fiber on the performance of poly(lactic acid) composites: Graphene oxide vs. silane coupling agents

Science.gov (United States)

Jing, Mengfan; Che, Junjin; Xu, Shuman; Liu, Zhenwei; Fu, Qiang

2018-03-01

In this work, a comparison study was carried out to investigate the efficacy of glass fiber (GF) in reinforcing poly(lactic acid) (PLA) by using traditional silane coupling agents (GF-S) and novel graphene oxide (GF-GO) as surface modifiers. The crystallization behavior of the PLA matrix was investigated by differential scanning calorimetry. The mechanical performances and the thermomechanical properties of the composites were evaluated by uniaxial tensile testing and dynamic mechanical analysis, respectively. For neat GF without any treatment, the poor interfacial adhesion and the sharp shortening of the GF length result in the relatively poor mechanical performances of PLA/GF composites. However, the incorporation of GF-S significantly improves the mechanical strength and keeps relatively good toughness of the composites, while GF-GO exhibits excellent nucleation ability for PLA and could moderately increase the modulus of the composites. The thermomechanical properties of the composites are improved markedly resulting from the crystallinity increase. The different surface modification of glass fiber influences the crystallinity of matrix, the interfacial interaction and the length of fiber, which altogether affect the mechanical performances of the prepared PLA/GF composites.

Supertoughened Biobased Poly(lactic acid)-Epoxidized Natural Rubber Thermoplastic Vulcanizates: Fabrication, Co-continuous Phase Structure, Interfacial in Situ Compatibilization, and Toughening Mechanism.

Science.gov (United States)

Wang, Youhong; Chen, Kunling; Xu, Chuanhui; Chen, Yukun

2015-09-10

In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel "sea-sea" co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical "sea-island" morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle-ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m(2), nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the effects of various DCP contents on the impact property were investigated. The toughening mechanism under impact testing was researched, and the influence factors for toughening were discussed.

Novel {beta}-cyclodextrin modified CdTe quantum dots as fluorescence nanosensor for acetylsalicylic acid and metabolites

Energy Technology Data Exchange (ETDEWEB)

Algarra, M. [Centro de Geologia do Porto, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Campos, B.B.; Aguiar, F.R.; Rodriguez-Borges, J.E. [Centro de Investigacao em Quimica (CIQ-UP), Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 169-007 Porto (Portugal); Esteves da Silva, J.C.G., E-mail: jcsilva@fc.up.pt [Centro de Investigacao em Quimica (CIQ-UP), Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 169-007 Porto (Portugal)

2012-05-01

{beta}-Cyclodextrin was modified with 11-[(ethoxycarbonyl)thio]undecanoic acid and used as a capping agent, together with mercaptosuccinic acid, to prepare water-stable CdTe quantum dots. The water soluble quantum dot obtained displays fluorescence with a maximum emission at 425 nm (under excitation at 300 nm) with lifetimes of 0.53, 4.8, 181, and 44.1 ns, respectively. The S-{beta}CD-MSA-CdTe can act as a nanoprobe that is due to the affinity of the cyclodextrin moiety for selected substances such as acetylsalicylic acid (ASA) and its metabolites as foreign species. The fluorescence of the S-{beta}CD-MSA-CdTe is enhanced on addition of ASA. Linear calibration plots are observed with ASA in concentrations between 0 and 1 mg/l, with a limit of detection at 8.5 Multiplication-Sign 10{sup -9} mol/l (1.5 ng/ml) and a precision as relative standard deviation of 1% (0.05 mg/l). The interference effect of certain compounds as ascorbic acid and its main metabolites such as salicylic, gentisic and salicyluric acid upon the obtained procedure was studied. Highlights: Black-Right-Pointing-Pointer Nanosensors constituted by CdTe quantum dots capped with modified cyclodextrin. Black-Right-Pointing-Pointer This nanomaterial shows fluorescence properties compatible with a semiconductor quantum dot. Black-Right-Pointing-Pointer The nanosensor shows fluorescence enhancement when inclusion complexes are formed with acetylsalicylic acid. Black-Right-Pointing-Pointer This nanomaterial has nanosensor potential taking into consideration the formation stability of the inclusion complex.

Phospholyl(borane) Amino Acids and Peptides: Stereoselective Synthesis and Fluorescent Properties with Large Stokes Shift.

Science.gov (United States)

Arribat, Mathieu; Rémond, Emmanuelle; Clément, Sébastien; Lee, Arie Van Der; Cavelier, Florine

2018-01-24

The synthesis of phospholyl(borane) amino acids was stereoselectively achieved by reaction of phospholide anion with iodo α-amino ester derived from l-aspartic acid or l-serine, followed by in situ complexation with borane. Phospholyl(borane) amino acids are easy to store and can be subjected to direct transformation into the corresponding free phospholyl, gold complex, oxide or sulfur derivatives as well as phospholinium salts, thus offering a variety of side chains. After selective deprotection of carboxylic function or amine, C- or N- peptide coupling with an alanine moiety proved the possible incorporation into peptides. Such phospholyl amino acid and peptide derivatives exhibit fluorescent properties with a large Stokes shift (160 nm) and fluorescence up to 535 nm, depending on the phosphole aromaticity and the chemical environment. These phospholyl(borane) amino acids constitute a new class of unnatural amino acids useful for structure-activities relationship studies and appear to be promising fluorophores for the development of labeled peptides.

In Vitro Evaluation of Essential Mechanical Properties and Cell Behaviors of a Novel Polylactic-co-Glycolic Acid (PLGA-Based Tubular Scaffold for Small-Diameter Vascular Tissue Engineering

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Nuoxin Wang

2017-07-01

Full Text Available In this paper, we investigate essential mechanical properties and cell behaviors of the scaffolds fabricated by rolling polylactic-co-glycolic acid (PLGA electrospinning (ES films for small-diameter vascular grafts (inner diameter < 6 mm. The newly developed strategy can be used to fabricate small diameter vascular grafts with or without pre-seeded cells, which are two main branches for small diameter vascular engineering. We demonstrate that the mechanical properties of our rolling-based scaffolds can be tuned flexibly by the number of layers. For cell-free scaffolds, with the increase of layer number, burst pressure and suture retention increase, elastic tensile modulus maintains unchanged statistically, but compliance and liquid leakage decrease. For cell-containing scaffolds, seeding cells will significantly decrease the liquid leakage, but there are no statistical differences for other mechanical properties; moreover, cells live and proliferate well in the scaffold after a 6-day culture.

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

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

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Lukas J. Patalag

2016-12-01

Full Text Available Herein, we report on the synthesis and characterization of novel fluorescent fatty acids with large Stokes shifts. Three examples consisting of the same number of carbon atoms and thus of similar chain length are presented differing in their degree of unsaturation. As major fluorogenic contributor at the terminus benzo[c][1,2,5]thiadiazole was used. Respective syntheses based on Wittig reactions followed by iodine-mediated isomerization are presented. The absorption properties are modulated by the number of conjugated C=C double bonds of the oligoene chain ranging from one to three. Large Stokes shifts of about 4900–5700 cm−1 and fluorescence quantum yields of up to 0.44 were observed.

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

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Liu Yong

2012-01-01

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

Bis-pyrene-modified unlocked nucleic acids: synthesis, hybridization studies, and fluorescent properties

DEFF Research Database (Denmark)

Perlíková, Pavla; Ejlersen, Maria; Langkjaer, Niels

2014-01-01

Efficient synthesis of a building block for the incorporation of a bis-pyrene-modified unlocked nucleic acid (UNA) into oligonucleotides (DNA*) was developed. The presence of bis-pyrene-modified UNA within a duplex leads to duplex destabilization that is more profound in DNA*/RNA and less distinc......)uracil:pyrene exciplex emission in the single-stranded form. Such fluorescent properties enable the application of bis-pyrene-modified UNA in the development of fluorescence probes for DNA/RNA detection and for detection of deletions at specific positions....

Cytocompatibility and Mechanical Properties of Short Phosphate Glass Fibre Reinforced Polylactic Acid (PLA Composites: Effect of Coupling Agent Mediated Interface

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Gavin Walker

2012-10-01

Full Text Available In this study three chemical agents Amino-propyl-triethoxy-silane (APS, sorbitol ended PLA oligomer (SPLA and Hexamethylene diisocyanate (HDI were identified to be used as coupling agents to react with the phosphate glass fibre (PGF reinforcement and the polylactic acid (PLA polymer matrix of the composite. Composites were prepared with short chopped strand fibres (l = 20 mm, ϕ = 20 µm in a random arrangement within PLA matrix. Improved, initial composite flexural strength (~20 MPa was observed for APS treated fibres, which was suggested to be due to enhanced bonding between the fibres and polymer matrix. Both APS and HDI treated fibres were suggested to be covalently linked with the PLA matrix. The hydrophobicity induced by these coupling agents (HDI, APS helped to resist hydrolysis of the interface and thus retained their mechanical properties for an extended period of time as compared to non-treated control. Approximately 70% of initial strength and 65% of initial modulus was retained by HDI treated fibre composites in contrast to the control, where only ~50% of strength and modulus was retained after 28 days of immersion in PBS at 37 °C. All coupling agent treated and control composites demonstrated good cytocompatibility which was comparable to the tissue culture polystyrene (TCP control, supporting the use of these materials as coupling agent’s within medical implant devices.

A Patient-Specific Polylactic Acid Bolus Made by a 3D Printer for Breast Cancer Radiation Therapy.

Directory of Open Access Journals (Sweden)

So-Yeon Park

Full Text Available The aim of this study was to assess the feasibility and advantages of a patient-specific breast bolus made using a 3D printer technique.We used the anthropomorphic female phantom with breast attachments, which volumes are 200, 300, 400, 500 and 650 cc. We simulated the treatment for a right breast patient using parallel opposed tangential fields. Treatment plans were used to investigate the effect of unwanted air gaps under bolus on the dose distribution of the whole breast. The commercial Super-Flex bolus and 3D-printed polylactic acid (PLA bolus were applied to investigate the skin dose of the breast with the MOSFET measurement. Two boluses of 3 and 5 mm thicknesses were selected.There was a good agreement between the dose distribution for a virtual bolus generated by the TPS and PLA bolus. The difference in dose distribution between the virtual bolus and Super-Flex bolus was significant within the bolus and breast due to unwanted air gaps. The average differences between calculated and measured doses in a 200 and 300 cc with PLA bolus were not significant, which were -0.7% and -0.6% for 3mm, and -1.1% and -1.1% for 5 mm, respectively. With the Super-Flex bolus, however, significant dose differences were observed (-5.1% and -3.2% for 3mm, and -6.3% and -4.2% for 5 mm.The 3D-printed solid bolus can reduce the uncertainty of the daily setup and help to overcome the dose discrepancy by unwanted air gaps in the breast cancer radiation therapy.

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

A novel fluorescence biosensor for sensitivity detection of tyrosinase and acid phosphatase based on nitrogen-doped graphene quantum dots.

Science.gov (United States)

Qu, Zhengyi; Na, Weidan; Liu, Xiaotong; Liu, Hua; Su, Xingguang

2018-01-02

In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL -1 and 0.04-0.7 mU mL -1 with a detection limit of 0.15 U mL -1 and 0.014 mU mL -1 , respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

Modifying the strength and strain concentration profile within collagen scaffolds using customizable arrays of poly-lactic acid fibers.

Science.gov (United States)

Mozdzen, Laura C; Vucetic, Alan; Harley, Brendan A C

2017-02-01

The tendon-to-bone junction is a highly specialized tissue which dissipates stress concentrations between mechanically dissimilar tendon and bone. Upon injury, the local heterogeneities across this insertion are not regenerated, leading to poor functional outcomes such as formation of scar tissue at the insertion and re-failure rates exceeding 90%. Although current tissue engineering methods are moving towards the development of spatially-graded biomaterials to begin to address these injuries, significant opportunities remain to engineer the often complex local mechanical behavior of such biomaterials to enhance their bioactivity. Here, we describe the use of three-dimensional printing techniques to create customizable arrays of poly-lactic acid (PLA) fibers that can be incorporated into a collagen scaffold under development for tendon bone junction repair. Notably, we use additive manufacturing concepts to generate arrays of spatially-graded fibers from biodegradable PLA that are incorporated into collagen scaffolds to create a collagen-PLA composite. We demonstrate the ability to tune the mechanical performance of the fiber-scaffold composite at the bulk scale. We also demonstrate the incorporation of spatially-heterogeneous fiber designs to establish non-uniform local mechanical performance of the composite biomaterial under tensile load, a critical element in the design of multi-compartment biomaterials for tendon-to-bone regeneration applications. Together, this work highlights the capacity to use multi-scale composite biomaterials to control local and bulk mechanical properties, and provides key insights into design elements under consideration for mechanically competent, multi-tissue regeneration platforms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improvement of thermal and mechanical properties of composite based on polylactic acid and microfibrillated cellulose through chemical modification

Science.gov (United States)

Suryanegara, L.; Nugraha, R. A.; Achmadi, S. S.

2017-07-01

Polylactic acid (PLA) is the most representative sustainable and bio-based polymer environmentally friendly that has a great potential to replace petroleum-based plastics. However, brittleness, low heat resistance, and slow crystallization limit the wide application of PLA. One of strategies to improve PLA properties is by reinforcing with microfibrillated cellulose (MFC). Unfortunately, the hydrophilic properties of MFC make it difficult to attain good dispersion in a hydrophobic PLA matrix. Therefore, modification of MFC was needed to increase its compatibility with PLA in the composite formation. In this experiment, MFC was modified with partial acetylation (degree of substitution: 1) and further grafted with lactide monomers through ring-opening polymerization using Sn(Oct)2 catalyst. The result of acetylation and grafting were verified by infrared spectra. Composites were prepared by mixing PLA (molecular weight of 200,000) and the modified MFC at 9:1 ratio through organic solvent method. Followed by 8 min-kneading and hot pressing at 180°C, the resulted composites were evaluated for their mechanical and thermal properties. Thermal characterization carried out using differential scanning calorimetry measurements showed that the presence of modified MFC increased the temperature of glass transition and accelerated the crystallization of PLA. Mechanical properties measurement showed that the presence of modified MFC enhanced the elongation at break (1.1 to 1.8%), tensile strength (14.9 to 25.7 MPa), and modulus of elasticity (1.7 to 2.1 GPa). These results demonstrated that the modified MFC could extend the application of PLA in industry.

Surface biofunctionalization of three-dimensional porous poly(lactic acid) scaffold using chitosan/OGP coating for bone tissue engineering.

Science.gov (United States)

Zeng, Sen; Ye, Jianhua; Cui, Zhixiang; Si, Junhui; Wang, Qianting; Wang, Xiaofeng; Peng, Kaiping; Chen, Wenzhe

2017-08-01

As one of the stimulators on bone formation, osteogenic growth peptide (OGP) improves both proliferation and differentiation of the bone cells in vitro and in vivo. The aim of this work was the preparation of three dimensional porous poly(lactic acid) (PLA) scaffold with high porosity from PLA-dioxane-water ternary system with the use of vacuum-assisted solvent casting, phase separation, solvent extraction and particle leaching methods. Then, by surface coating of PLA scaffold with chitosan (CS)/OGP solution, biofunctionalization of PLA scaffold had been completed for application in bone regeneration. The effects of frozen temperature (-20, -50, -80°C) and PLA solution concentration (10, 12, 14wt%) on the microstructure, water absorption, porosity, hydrophilicity, mechanical properties, and biocompatibility of PLA and CS/OGP/PLA scaffold were investigated. Results showed that both PLA and CS/OGP/PLA scaffolds have an interconnected network structure and a porosity of up to 96.1% and 91.5%, respectively. The CS/OGP/PLA scaffold exhibited better hydrophilicity and mechanical properties than that of uncoated PLA scaffold. Moreover, the results of cell culture test showed that CS/OGP coating could stimulate the proliferation and growth of osteoblast cells on CS/OGP/PLA scaffold. These finding suggested that the surface biofunctionalization by CS/OGP coating layer could be an effective method on enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering application and the developed porous CS/OGP/PLA scaffold should be considered as alternative biomaterials for bone regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of polyethylene glycol/polylactic acid films in the prevention of adhesions in the rabbit adhesion formation and reformation sidewall models.

Science.gov (United States)

Rodgers, K; Cohn, D; Hotovely, A; Pines, E; Diamond, M P; diZerega, G

1998-03-01

To assess the efficacy of bioresorbable films consisting of various polyethylene glycol 6000 and polylactic acid block copolymers on the formation and reformation of adhesions in rabbit models of adhesion development between the sidewall to the adjacent cecum and bowel. The composition of the different polymers was expressed by the number of monomeric units in the block, namely, ethylene oxide (EO) and lactic acid (LA), respectively. Studies of the efficacy of EO/LA films were conducted in rabbit sidewall adhesion formation studies in the presence and absence of blood and in rabbit adhesion reformation studies. REPEL (Life Medical Sciences, Edison, NJ), a film of EO/LA ratio 3.0 manufactured under commercial conditions, was also tested in these animal models. University-based laboratory. New Zealand white rabbits. Placement of films of various EO/LA ratios at the site of injury to the parietal peritoneum. Adhesion formation and reformation. Films of various EO/LA ratios, Seprafilm (Genzyme, Cambridge, MA) and Interceed (Johnson and Johnson Medical, Arlington, TX) placed over an area of excised sidewall at the time of initial injury were highly efficacious in the prevention of adhesion formation. A film of EO/LA ratio 3.7, in contrast with Interceed, was also shown to maintain maximal efficacy in the reduction of adhesion formation in the presence of blood. Further, a film of EO/LA ratio 3.0 produced under commercial conditions, REPEL, was highly efficacious in reducing adhesion development in the rabbit models of adhesion and reformation. These studies suggest that bioresorbable EO/LA films reduced adhesion development in rabbit models of adhesion formation and reformation.

Comparative Study of Chemical, Mechanical, Thermal, and Barrier Properties of Poly(Lactic Acid Plasticized with Epoxidized Soybean Oil and Epoxidized Palm Oil

Directory of Open Access Journals (Sweden)

Yee Bond Tee

2015-12-01

Full Text Available To investigate epoxidized palm oil’s (EPO potential as plasticizer for poly(lactic acid (PLA, its plasticizing effect was compared with commercialized epoxidized soybean oil (ESO. The plasticizers were respectively melt-compounded into PLA at 3, 5, 10, and 15 wt.%. As it was aimed for the blends to be characterized towards packaging appropriate for food products, they were hot-pressed into ~0.3-mm sheets, which is the approximate thickness of clamshell packaging. Fourier transform infrared spectroscopy (FTIR confirmed the plasticizers’ compatibility with PLA. At similar loadings, EPO was superior in reinforcing elongation at break (EAB, thermal, and barrier properties of PLA. The ductility of PLA was notably improved to 50.0% with addition of 3 wt.% of EPO. From thermogravimetric analysis (TGA, PLA/EPO5 improved PLA’s thermal stability, while all PLA/ESO blends reported reduced thermal stability. From differential scanning calorimetry (DSC, the increase in crystallinity and the shifts in enthalpy of fusions in all plasticized blends denoted facilitation of PLA to form thermally stable α-form crystals. The addition of EPO enabled PLA to become highly impermeable to oxygen, which can extend its potential in packaging extensive range of oxygen sensitive food.

Fluorescent boronic acid terminated polymer grafted silica particles synthesized via click chemistry for affinity separation of saccharides

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhifeng, E-mail: 897061147@qq.com; Deng, Peihong; Tang, Siping; Li, Junhua

2014-07-01

Boronic acids are important for effective separation of biological active cis-diols. For the purpose of constructing a new type of saccharide-sensitive material which can not only provide convenient separation but also improve the access of boronic acid to guest molecules, the fluorogenic boronic acid terminated, thermo-sensitive polymers (BA-polyNIPAm) were grafted to an alkyne modified silica gel through the exploitation of click chemistry. The BA-polyNIPAm grafted silica gel (BA-polyNIPAm-SG) was characterized by FT-IR, fluorescence spectra, fluorescence microscopy, elemental analysis (EA), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and so on. BA-polyNIPAm-SG displayed affinity binding ability for saccharides under physiological pH value and allowed saccharides to be conveniently separated from solution. The maximum binding capacities for fructose and glucose are 83.2 μmol/g and 70.4 μmol/g polymer, respectively. The intensity of fluorescence emission of BA-polyNIPAm-SG increased with the increasing of fructose concentration. The present study provides a new kind of composite material which contains moveable and flexible grippers for recognizing and binding guest molecules. - Highlights: • Fluorogenic boronic acid terminated polymers were conjugated to silica particle. • The prepared material can conveniently separate saccharides from solution. • The prepared material displays increased fluorescence emission upon binding fructose.

Fluorescent boronic acid terminated polymer grafted silica particles synthesized via click chemistry for affinity separation of saccharides

International Nuclear Information System (INIS)

Xu, Zhifeng; Deng, Peihong; Tang, Siping; Li, Junhua

2014-01-01

Boronic acids are important for effective separation of biological active cis-diols. For the purpose of constructing a new type of saccharide-sensitive material which can not only provide convenient separation but also improve the access of boronic acid to guest molecules, the fluorogenic boronic acid terminated, thermo-sensitive polymers (BA-polyNIPAm) were grafted to an alkyne modified silica gel through the exploitation of click chemistry. The BA-polyNIPAm grafted silica gel (BA-polyNIPAm-SG) was characterized by FT-IR, fluorescence spectra, fluorescence microscopy, elemental analysis (EA), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and so on. BA-polyNIPAm-SG displayed affinity binding ability for saccharides under physiological pH value and allowed saccharides to be conveniently separated from solution. The maximum binding capacities for fructose and glucose are 83.2 μmol/g and 70.4 μmol/g polymer, respectively. The intensity of fluorescence emission of BA-polyNIPAm-SG increased with the increasing of fructose concentration. The present study provides a new kind of composite material which contains moveable and flexible grippers for recognizing and binding guest molecules. - Highlights: • Fluorogenic boronic acid terminated polymers were conjugated to silica particle. • The prepared material can conveniently separate saccharides from solution. • The prepared material displays increased fluorescence emission upon binding fructose

Chirality Matters: Synthesis and Consumption of the d-Enantiomer of Lactic Acid by Synechocystis sp. Strain PCC6803

NARCIS (Netherlands)

Angermayr, S.A.; van der Woude, A.D.; Correddu, D.; Kern, R.; Hagemann, M.; Hellingwerf, K.J.

2015-01-01

Both enantiomers of lactic acid, l-lactic acid and d-lactic acid, can be produced in a sustainable way by a photosynthetic microbial cell factory and thus from CO2, sunlight, and water. Several properties of polylactic acid (a polyester of polymerized lactic acid) depend on the controlled blend of

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

Directory of Open Access Journals (Sweden)

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.

Poly (Methyl Methacrylate) (PMMA) and Polyactic Acid Nanoparticles as Adjuvents for Peroral Vaccines

National Research Council Canada - National Science Library

Kreuter, Jorg

1999-01-01

...) or the employment of polylactic acid did not achieve a significant protection. Protection did not correlate at all with ELISA antibodies against ricin after oral as well as subcutaneous vaccination...

Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model

Science.gov (United States)

Zhang, Haifeng; Mao, Xiyuan; Du, Zijing; Jiang, Wenbo; Han, Xiuguo; Zhao, Danyang; Han, Dong; Li, Qingfeng

2016-01-01

We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500 μm and 60% porosity was fabricated by three-dimensional printing. Three-dimensional printed PLA/HA, β-tricalcium phosphate (β-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteopontin (OPN) and collagen type I (COL-1). Moreover, the biocompatibility, bone repairing capacity and degradation in three different bone substitute materials were estimated using a critical-size rat calvarial defect model in vivo. The defects were evaluated by micro-computed tomography and histological analysis at four and eight weeks after surgery, respectively. The results showed that each of the studied scaffolds had its own specific merits and drawbacks. Three-dimensional printed PLA/HA scaffolds possessed good biocompatibility and stimulated BMSC cell proliferation and differentiation to osteogenic cells. The outcomes in vivo revealed that 3D printed PLA/HA scaffolds had good osteogenic capability and biodegradation activity with no difference in inflammation reaction. Therefore, 3D printed PLA/HA scaffolds have potential applications in bone tissue engineering and may be used as graft substitutes in reconstructive surgery.

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

Science.gov (United States)

Dhar, Prodyut; Kumar, Amit; Katiyar, Vimal

2016-07-20

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

Pyrolysis-gas chromatography-isotope ratio mass spectrometry for monitoring natural additives in polylactic acid active food packages.

Science.gov (United States)

Llana-Ruíz-Cabello, M; Pichardo, S; Jiménez-Morillo, N T; González-Vila, F J; Guillamón, E; Bermúdez, J M; Aucejo, S; Camean, A M; González-Pérez, J A

2017-11-24

Compound-specific isotope analysis (CSIA) usually requires preparative steps (pretreatments, extraction, derivatization) to get amenable chromatographic analytes from bulk geological, biological or synthetic materials. Analytical pyrolysis (Py-GC/MS) can help to overcome such sample manipulation. This communication describe the results obtained by hyphenating analytical pyrolysis (Py-GC) with carbon isotope-ratio mass spectrometry (IRMS) for the analysis of a polylactic acid (PLA) a based bio-plastic extruded with variable quantities of a natural plant extract or oregano essential oil. The chemical structural information of pyrolysates was first determined by conventional analytical pyrolysis and the measure of δ 13 C in specific compounds was done by coupling a pyrolysis unit to a gas chromatograph connected to a continuous flow IRMS unit (Py-GC-C-IRMS). Using this Py-CSIA device it was possible to trace natural additives with depleted δ 13 C values produced by C3 photosystem vegetation (cymene: -26.7‰±2.52; terpinene: -27.1‰±0.13 and carvacrol: -27.5‰±1.80 from oregano and two unknown structures: -23.3‰±3.32 and -24.4‰±1.70 and butyl valerate: -24.1‰±3.55 from Allium spp.), within the naturally isotopically enriched bio-plastic backbone derived from corn (C4 vegetation) starch (cyclopentanones: -14.2‰±2.11; lactide enantiomers: -9.2‰±1.56 and larger polymeric units: -17.2‰±1.71). This is the first application of Py-CSIA to characterize a bio-plastic and is shown as a promising tool to study such materials, providing not only a fingerprinting, but also valuable information about the origin of the materials, allowing the traceability of additives and minimizing sample preparation. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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.

Fluorescence Stability of Mercaptopropionic Acid Capped Cadmium Telluride Quantum Dots in Various Biochemical Buffers.

Science.gov (United States)

Borse, Vivek; Kashikar, Adisha; Srivastava, Rohit

2018-04-01

Quantum dots are the semiconductor nanocrystals having unique optical and electronic properties. Quantum dots are category of fluorescent labels utilized for biological tagging, biosensing, bioassays, bioimaging and in vivo imaging as they exhibit very small size, signal brightness, photostability, tuning of light emission range, longer photoluminescence decay time as compared to organic dyes. In this work, we have synthesized and characterized mercaptopropionic acid capped cadmium telluride quantum dots (MPA-CdTe QDs) using hydrothermal method. The study further reports fluorescence intensity stability of quantum dots suspended in different buffers of varying concentration (1-100 mM), stored at various photophysical conditions. Fluorescence intensity values were reduced with increase in buffer concentration. When the samples were stored at room temperature in ambient light condition the quantum dots suspended in different buffers lost the fluorescence intensity after day 15 (except TRIS II). Fluorescence intensity values were found stable for more than 30 days when the samples were stored in dark condition. Samples stored in refrigerator displayed modest fluorescence intensity even after 300 days of storage. Thus, storage of MPA-CdTe QDs in refrigerator may be the suitable choice to maintain its fluorescence stability for longer time for further application.

Core-shell nanofibers of curcumin/cyclodextrin inclusion complex and polylactic acid: Enhanced water solubility and slow release of curcumin.

Science.gov (United States)

Aytac, Zeynep; Uyar, Tamer

2017-02-25

Core-shell nanofibers were designed via electrospinning using inclusion complex (IC) of model hydrophobic drug (curcumin, CUR) with cyclodextrin (CD) in the core and polymer (polylactic acid, PLA) in the shell (cCUR/HPβCD-IC-sPLA-NF). CD-IC of CUR and HPβCD was formed at 1:2 molar ratio. The successful formation of core-shell nanofibers was revealed by TEM and CLSM images. cCUR/HPβCD-IC-sPLA-NF released CUR slowly but much more in total than PLA-CUR-NF at pH 1 and pH 7.4 due to the restriction of CUR in the core of nanofibers and solubility improvement shown in phase solubility diagram, respectively. Improved antioxidant activity of cCUR/HPβCD-IC-sPLA-NF in methanol:water (1:1) is related with the solubility enhancement achieved in water based system. The slow reaction of cCUR/HPβCD-IC-sPLA-NF in methanol is associated with the shell inhibiting the quick release of CUR. On the other hand, cCUR/HPβCD-IC-sPLA-NF exhibited slightly higher rate of antioxidant activity than PLA-CUR-NF in methanol:water (1:1) owing to the enhanced solubility. To conclude, slow release of CUR was achieved by core-shell nanofiber structure and inclusion complexation of CUR with HPβCD provides high solubility. Briefly, electrospinning of core-shell nanofibers with CD-IC core could offer slow release of drugs as well as solubility enhancement for hydrophobic drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of sustained release polylactate electron donors for removal of hexavalent chromium from contaminated groundwater

Energy Technology Data Exchange (ETDEWEB)

Brodie, E.L.; Joyner, D. C.; Faybishenko, B.; Conrad, M. E.; Rios-Velazquez, C.; Mork, B.; Willet, A.; Koenigsberg, S.; Herman, D.; Firestone, M. K.; Hazen, T. C.; Malave, Josue; Martinez, Ramon

2011-02-15

To evaluate the efficacy of bioimmobilization of Cr(VI) in groundwater at the Department of Energy Hanford site, we conducted a series of microcosm experiments using a range of commercial electron donors with varying degrees of lactate polymerization (polylactate). These experiments were conducted using Hanford Formation sediments (coarse sand and gravel) immersed in Hanford groundwater, which were amended with Cr(VI) and several types of lactate-based electron donors (Hydrogen Release Compound, HRC; primer-HRC, pHRC; extended release HRC) and the polylactate-cysteine form (Metal Remediation Compound, MRC). The results showed that polylactate compounds stimulated an increase in bacterial biomass and activity to a greater extent than sodium lactate when applied at equivalent carbon concentrations. At the same time, concentrations of headspace hydrogen and methane increased and correlated with changes in the microbial community structure. Enrichment of Pseudomonas spp. occurred with all lactate additions, and enrichment of sulfate-reducing Desulfosporosinus spp. occurred with almost complete sulfate reduction. The results of these experiments demonstrate that amendment with the pHRC and MRC forms result in effective removal of Cr(VI) from solution most likely by both direct (enzymatic) and indirect (microbially generated reductant) mechanisms.

Antimicrobial activity of a new synthetic peptide loaded in polylactic acid or poly(lactic-co-glycolic) acid nanoparticles against Pseudomonas aeruginosa, Escherichia coli O157:H7 and methicillin resistant Staphylococcus aureus (MRSA)

Science.gov (United States)

Cruz, J.; Flórez, J.; Torres, R.; Urquiza, M.; Gutiérrez, J. A.; Guzmán, F.; Ortiz, C. C.

2017-03-01

Nanocarrier systems are currently being developed for peptide, protein and gene delivery to protect them in the blood circulation and in the gastrointestinal tract. Polylactic acid (PLA) and poly(lactic-co-glycolic) acid (PLGA) nanoparticles loaded with a new antimicrobial GIBIM-P5S9K peptide were obtained by the double emulsion solvent extraction/evaporation method. PLA- and PLGA-NPs were spherical with sizes between 300 and 400 nm for PLA and 200 and 300 nm for PLGA and 20 mV. The peptide-loading efficiency of PLA-NP and PLGA-NPs was 75% and 55%, respectively. PLA- and PLGA-NPs released around 50% of this peptide over 8 h. In 10% human sera the size of peptide loaded PLA- and PLGA-NPs increased between 25.2% and 39.3%, the PDI changed from 3.2 to 5.1 and the surface charge from -7.15 to 14.6 mV. Both peptide loaded PLA- and PLGA-NPs at 0.5 μM peptide concentration inhibited the growth of Escherichia coli O157:H7 (E. coli O157:H7), methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas. aeruginosa (P. aeruginosa). In contrast, free peptide inhibited at 10 μM but did not inhibit at 0.5 and 1 μM. These PLA- and PLGA-NPs presented <10% hemolysis indicating that they are hemocompatible and promising for delivery and protection system of GIBIM-P5S9K peptide.

Polydiacetylene liposomes with phenylboronic acid tags: a fluorescence turn-on sensor for sialic acid detection and cell-surface glycan imaging.

Science.gov (United States)

Wang, Dong-En; Yan, Jiahang; Jiang, Jingjing; Liu, Xiang; Tian, Chang; Xu, Juan; Yuan, Mao-Sen; Han, Xiang; Wang, Jinyi

2018-03-01

Sialic acid (SA) located at the terminal end of glycans on cell membranes has been shown to play an important yet distinctive role in various biological and pathological processes. Effective methods for the facile, sensitive and in situ analysis of SA on living cell surfaces are of great significance in terms of clinical diagnostics and therapeutics. Here, a new polydiacetylene (PDA) liposome-based sensor system bearing phenylboronic acid (PBA) and 1,8-naphthalimide derived fluorophore moieties was developed as a fluorescence turn-on sensor for the detection of free SA in aqueous solution and the in situ imaging of SA-terminated glycans on living cell surfaces. In the sensor system, three diacetylene monomers, PCDA-pBA, PCDA-Nap and PCDA-EA, were designed and synthesized to construct the composite PDA liposome sensor. The monomer PCDA-pBA modified with PBA molecules was employed as a receptor for SA recognition, while the monomer PCDA-Nap containing a 1,8-naphthalimide derivative fluorophore was used for fluorescence signaling. When the composite PDA liposomes were formed, the energy transfer between the fluorophore and the conjugated backbone could directly quench the fluorescence of the fluorophore. In the presence of additional SA or SA abundant cells, the strong binding of SA with PBA moieties disturbed the pendent side chain conformation, resulting in the fluorescence restoration of the fluorophore. The proposed methods realized the fluorescence turn-on detection of free SA in aqueous solution and the in situ imaging of SA on living MCF-7 cell surfaces. This work provides a new potential tool for simple and selective analysis of SA on living cell membranes.

Phenylboronic acid functionalized reduced graphene oxide based fluorescence nano sensor for glucose sensing

Energy Technology Data Exchange (ETDEWEB)

Basiruddin, SK; Swain, Sarat K., E-mail: swainsk2@yahoo.co.in

2016-01-01

Reduced graphene has emerged as promising tools for detection based application of biomolecules as it has high surface area with strong fluorescence quenching property. We have used the concept of fluorescent quenching property of reduced graphene oxide to the fluorescent probes which are close vicinity of its surface. In present work, we have synthesized fluorescent based nano-sensor consist of phenylboronic acid functionalized reduced graphene oxide (rGO–PBA) and di-ol modified fluorescent probe for detection of biologically important glucose molecules. This fluorescent graphene based nano-probe has been characterized by high resolution transmission electron microscope (HRTEM), Atomic force microscope (AFM), UV–visible, Photo-luminescence (PL) and Fourier transformed infrared (FT-IR) spectroscopy. Finally, using this PBA functionalized reduced GO based nano-sensor, we were able to detect glucose molecule in the range of 2 mg/mL to 75 mg/mL in aqueous solution of pH 7.4. - Highlights: • Easy and simple synthesis of PBA functionalized reduced GO based nano probe. • PBA functionalized reduced GO graphene based nano-probes are characterized. • PBA functionalized reduced GO nano probe is used to detect glucose molecules. • It is very cost-effective and enzyme-free detection of glucose in solution.

[Effects of simulated acid rain on Quercus glauca seedlings photosynthesis and chlorophyll fluorescence].

Science.gov (United States)

Li, Jia; Jiang, Hong; Yu, Shu-quan; Jiang, Fu-wei; Yin, Xiu-min; Lu, Mei-juan

2009-09-01

Taking the seedlings of Quercus glauca, a dominant evergreen broadleaf tree species in subtropical area, as test materials, this paper studied their photosynthesis, chlorophyll fluorescence, and chlorophyll content under effects of simulated acid rain with pH 2.5, 4.0, and 5.6 (CK). After 2-year acid rain stress, the net photosynthetic rate of Q. glauca increased significantly with decreasing pH of acid rain. The acid rain with pH 2.5 and 4.0 increased the stomatal conductance and transpiration rate, and the effect was more significant under pH 2.5. The intercellular CO2 concentration decreased in the order of pH 2.5 > pH 5.6 > pH 4.0. The maximum photosynthetic rate, light compensation point, light saturation point, and dark respiration rate were significantly higher under pH 2.5 and 4.0 than under pH 5.6, while the apparent quantum yield was not sensitive to acid rain stress. The maximal photochemical efficiency of PS II and the potential activity of PS II under pH 2.5 and 4.0 were significantly higher than those under pH 5.6. The relative chlorophyll content was in the order of pH 2.5 > pH 5.6 > pH 4.0, and there was a significant difference between pH 2.5 and 4.0. All the results suggested that the photosynthesis and chlorophyll fluorescence of Q. glauca increased under the effects of acid rain with pH 2.5 and 4.0, and the acid rain with pH 2.5 had more obvious effects.

Folic acid-targeted magnetic Tb-doped CeF3 fluorescent nanoparticles as bimodal probes for cellular fluorescence and magnetic resonance imaging.

Science.gov (United States)

Ma, Zhi-Ya; Liu, Yu-Ping; Bai, Ling-Yu; An, Jie; Zhang, Lin; Xuan, Yang; Zhang, Xiao-Shuai; Zhao, Yuan-Di

2015-10-07

Magnetic fluorescent nanoparticles (NPs) have great potential applications for diagnostics, imaging and therapy. We developed a facile polyol method to synthesize multifunctional Fe3O4@CeF3:Tb@CeF3 NPs with small size (CA) to obtain carboxyl-functionalized NPs (Fe3O4@CeF3:Tb@CeF3-COOH). Folic acid (FA) as an affinity ligand was then covalently conjugated onto NPs to yield Fe3O4@CeF3:Tb@CeF3-FA NPs. They were then applied as multimodal imaging agents for simultaneous in vitro targeted fluorescence imaging and magnetic resonance imaging (MRI) of HeLa cells with overexpressed folate receptors (FR). The results indicated that these NPs had strong luminescence and enhanced T2-weighted MR contrast and would be promising candidates as multimodal probes for both fluorescence and MRI imaging.

Polylactic Acid-Based Polymer Blends for Durable Applications

Science.gov (United States)

Finniss, Adam

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

INFLUENCE OF PACKAGING MATERIAL AND STORAGE TIME ON PHYSICAL, CHEMICAL AND MICROBIOLOGICAL PROPERTIES OF SET YOGURT: A COMPARATIVE STUDY BETWEEN MODIFIED BIODEGRADABLE POLY(LACTIC ACID AND POLYPROPYLENE

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NAWADON PETCHWATTANA

2016-10-01

Full Text Available The current paper investigates the influence of storage time and type of polymeric packaging material on the chemical, physical and microbiological properties of set yogurt. Firstly, poly(lactic acid (PLA was modified by using a core-shell rubber (CSR and an acrylic processing aid (PA to produce PLA with high toughness and good processability. Secondly, an appropriate PLA/PA/CSR composition was selected and fabricated to yogurt cup. The yogurt was stored in both modified PLA and polypropylene (PP packages to observe some physical, chemical and biological changes. Finally, the biodegradation test was made on both packages and compared with that cellulose. Experimental results revealed that adding 5wt% CSR gave PLA/PA as tough as PP. Types of packaging material and storage time did not change the color of yogurt. The number of lactic acid bacteria grew significantly after they had been incubated for 6 days. The bacterial viability decreased dramatically due to the increased acidity and the decreased pH. A positive impact on the viability of bacterial growth was found when yogurt was stored in modified PLA package. This made yogurt had more health benefits than stored in PP package. The biodegradation test results indicated that the modified PLA degraded at a rapid rate. It achieved approximately 50% biodegradation within 40 days which was comparable to the time required to degrade the cellulose, whereas PP was non-biodegradable over the period studied. In summary, substitution conventional PP by a novel modified PLA seems to be a better way for both the health and the environment benefits.

Far-red fluorescent probes for canonical and non-canonical nucleic acid structures: current progress and future implications.

Science.gov (United States)

Suseela, Y V; Narayanaswamy, Nagarjun; Pratihar, Sumon; Govindaraju, Thimmaiah

2018-02-05

The structural diversity and functional relevance of nucleic acids (NAs), mainly deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are indispensable for almost all living organisms, with minute aberrations in their structure and function becoming causative factors in numerous human diseases. The standard structures of NAs, termed canonical structures, are supported by Watson-Crick hydrogen bonding. Under special physiological conditions, NAs adopt distinct spatial organisations, giving rise to non-canonical conformations supported by hydrogen bonding other than the Watson-Crick type; such non-canonical structures have a definite function in controlling gene expression and are considered as novel diagnostic and therapeutic targets. Development of molecular probes for these canonical and non-canonical DNA/RNA structures has been an active field of research. Among the numerous probes studied, probes with turn-on fluorescence in the far-red (600-750 nm) region are highly sought-after due to minimal autofluorescence and cellular damage. Far-red fluorescent probes are vital for real-time imaging of NAs in live cells as they provide good resolution and minimal perturbation of the cell under investigation. In this review, we present recent advances in the area of far-red fluorescent probes of DNA/RNA and non-canonical G-quadruplex structures. For the sake of continuity and completeness, we provide a brief overview of visible fluorescent probes. Utmost importance is given to design criteria, characteristic properties and biological applications, including in cellulo imaging, apart from critical discussion on limitations of the far-red fluorescent probes. Finally, we offer current and future prospects in targeting canonical and non-canonical NAs specific to cellular organelles, through sequence- and conformation-specific far-red fluorescent probes. We also cover their implications in chemical and molecular biology, with particular focus on decoding various disease

A lysosome-locating and acidic pH-activatable fluorescent probe for visualizing endogenous H2O2 in lysosomes.

Science.gov (United States)

Liu, Jun; Zhou, Shunqing; Ren, Jing; Wu, Chuanliu; Zhao, Yibing

2017-11-20

There is increasing evidence indicating that lysosomal H 2 O 2 is closely related to autophagy and apoptotic pathways under both physiological and pathological conditions. Therefore, fluorescent probes that can be exploited to visualize H 2 O 2 in lysosomes are potential tools for exploring diverse roles of H 2 O 2 in cells. However, functional exploration of lysosomal H 2 O 2 is limited by the lack of fluorescent probes capable of compatibly sensing H 2 O 2 under weak acidic conditions (pH = 4.5) of lysosomes. Lower spatial resolution of the fluorescent visualization of lysosomal H 2 O 2 might be caused by the interference of signals from cytosolic and mitochondrial H 2 O 2 , as well as the non-specific distribution of the probes in cells. In this work, we developed a lysosome-locating and acidic-pH-activatable fluorescent probe for the detection and visualization of H 2 O 2 in lysosomes, which consists of a H 2 O 2 -responsive boronate unit, a lysosome-locating morpholine group, and a pH-activatable benzorhodol fluorophore. The response of the fluorescent probe to H 2 O 2 is significantly more pronounced under acidic pH conditions than that under neutral pH conditions. Notably, the present probe enables the fluorescence sensing of endogenous lysosomal H 2 O 2 in living cells without external stimulations, with signal interference from the cytoplasm and other intracellular organelles being negligible.

Rapid fluorometric determination of perfluorooctanoic acid by its quenching effect on the fluorescence of quantum dots

International Nuclear Information System (INIS)

Liu, Qi; Huang, Aizhen; Wang, Nan; Zheng, Guan; Zhu, Lihua

2015-01-01

Analysis of perfluorooctanoic acid (PFOA) usually requires a combination of high-performance liquid chromatography and mass spectrometry, which is expensive and time-consuming. In the present work, water-soluble CdS quantum dots (QDs) were employed to develop a simple and rapid fluorometric method for the determination of PFOA. Strongly fluorescent CdS QDs were prepared by using 3-mercaptopropionic acid (MPA) as a stabilizer. It was observed that PFOA strongly quenched the fluorescence emission of the MPA-CdS QDs because PFOA promotes the aggregation of MPA-CdS QDs through a fluorine–fluorine affinity interaction. Under optimum conditions, the fluorescence intensity of MPA-CdS QDs was observed to decrease linearly with an increase in the concentration of PFOA from 0.5 to 40 μmol L −1 , with a limit of detection of 0.3 μmol L −1 . This new method was successfully implemented for the analysis of PFOA-spiked textile samples, with recoveries ranging from 95% to 113%. - Highlights: • PFOA significantly quenched the fluorescence emission of quantum dots (QDs). • A rapid and simple fluorescence sensor was proposed for determining PFOA by QDs. • PFOA determination could be completed within approximately 10 min. • The developed method had a working range of 0.5 to 40 μmol L −1 and a detection limit of 0.3 μmol L −1

Fabrication, characterization and in vitro evaluation of triboelectric nanogenerator based on 317 L stainless steel and polylactic acid

Science.gov (United States)

Li, Wei; Xu, Xiaoxue; Li, Wenjiang; Zhao, Yun; Chen, Minfang

2018-05-01

A novel, cost-effective biomedical triboelectric nanogenerator (TENG) has been fabricated based on biocompatible medical 317 L stainless steel (317 L SS) and polylactic acid (PLLA) films as the friction layers, whose surface roughness was designed by simple and low-cost laser etching and hot-embossing template methods, respectively. With the increase of the TENG’s tribo-interface roughness and the molecular weight of the PLLA, the power output of TENG was greatly increased owing to more charges being produced and the excellent mechanical properties PLLA possessed. When the 317 L SS plate surface roughness was 66.54% measured by the image J software and the PLLA film with a larger molecular weight at 500 000 was patterned with the 1000 mesh screen template, the maximal short current, open voltage and transferred charge of TENG reached up to 60 μA, 150 V and ∼125 nC, respectively. At the optimum condition, the maximum instantaneous power of the TENG was 5.5 mW at a load resistance of ∼2.5 MΩ and the saturation voltage was 20 V when the load capacitance was 0.1 μF. The evaluation of the TENG’s biocompatibility in vitro was performed by using the simulated body fluid (SBF) solution and ultrasonic wave to mimic the body environment with various vibrations, respectively. After 6 h ultrasonic bath for the directly immersed TENG, the pH of the SBF solution just changed slightly from 7.4 to 7.61 with an acceptable degradation of the output power of TENG. The cellular toxicity test also demonstrates that the mouse L929 cells grow excellently with normal morphology even after 5 d. These results indicate that the TENG has a good stability in the body environment and the output performance can still drive many micro-medical devices.

Migration of antioxidants from polylactic acid films: A parameter estimation approach and an overview of the current mass transfer models.

Science.gov (United States)

Samsudin, Hayati; Auras, Rafael; Mishra, Dharmendra; Dolan, Kirk; Burgess, Gary; Rubino, Maria; Selke, Susan; Soto-Valdez, Herlinda

2018-01-01

Migration studies of chemicals from contact materials have been widely conducted due to their importance in determining the safety and shelf life of a food product in their packages. The US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) require this safety assessment for food contact materials. So, migration experiments are theoretically designed and experimentally conducted to obtain data that can be used to assess the kinetics of chemical release. In this work, a parameter estimation approach was used to review and to determine the mass transfer partition and diffusion coefficients governing the migration process of eight antioxidants from poly(lactic acid), PLA, based films into water/ethanol solutions at temperatures between 20 and 50°C. Scaled sensitivity coefficients were calculated to assess simultaneously estimation of a number of mass transfer parameters. An optimal experimental design approach was performed to show the importance of properly designing a migration experiment. Additional parameters also provide better insights on migration of the antioxidants. For example, the partition coefficients could be better estimated using data from the early part of the experiment instead at the end. Experiments could be conducted for shorter periods of time saving time and resources. Diffusion coefficients of the eight antioxidants from PLA films were between 0.2 and 19×10 -14 m 2 /s at ~40°C. The use of parameter estimation approach provided additional and useful insights about the migration of antioxidants from PLA films. Copyright © 2017 Elsevier Ltd. All rights reserved.

Collagen-coated polylactic-glycolic acid (PLGA) seeded with neural-differentiated human mesenchymal stem cells as a potential nerve conduit.

Science.gov (United States)

Sulong, Ahmad Fadzli; Hassan, Nur Hidayah; Hwei, Ng Min; Lokanathan, Yogeswaran; Naicker, Amaramalar Selvi; Abdullah, Shalimar; Yusof, Mohd Reusmaazran; Htwe, Ohnmar; Idrus, Ruszymah Bt Hj; Haflah, Nor Hazla Mohamed

2014-01-01

Autologous nerve grafts to bridge nerve gaps pose various drawbacks. Nerve tissue engineering to promote nerve regeneration using artificial neural conduits has emerged as a promising alternative. To develop an artificial nerve conduit using collagen-coated polylactic-glycolic acid (PLGA) and to analyse the survivability and propagating ability of the neuro-differentiated human mesenchymal stem cells in this conduit. The PLGA conduit was constructed by dip-molding method and coated with collagen by immersing the conduit in collagen bath. The ultra structure of the conduits were examined before they were seeded with neural-differentiated human mesenchymal stem cells (nMSC) and implanted sub-muscularly on nude mice thighs. The non-collagen-coated PLGA conduit seeded with nMSC and non-seeded non-collagen-coated PLGA conduit were also implanted for comparison purposes. The survivability and propagation ability of nMSC was studied by histological and immunohistochemical analysis. The collagen-coated conduits had a smooth inner wall and a highly porous outer wall. Conduits coated with collagen and seeded with nMSCs produced the most number of cells after 3 weeks. The best conduit based on the number of cells contained within it after 3 weeks was the collagen-coated PLGA conduit seeded with neuro-transdifferentiated cells. The collagen-coated PLGA conduit found to be suitable for attachment, survival and proliferation of the nMSC. Minimal cell infiltration was found in the implanted conduits where nearly all of the cells found in the cell seeded conduits are non-mouse origin and have neural cell markers, which exhibit the biocompatibility of the conduits. The collagen-coated PLGA conduit is biocompatible, non-cytotoxic and suitable for use as artificial nerve conduits.

Accessibility of nucleic acid-complexed biomolecules to hydroxyl radicals correlates with their conformation: a fluorescence polarization spectroscopy study

International Nuclear Information System (INIS)

Makrigiorgos, G.M.; Bump, E.; Huang, C.; Kassis, A.I.; Baranowska-Kortylewicz, J.

1994-01-01

A fluorescence methodology has been developed to examine the relationship between the conformational state of specific biomolecules in simple chromatin models and their accessibility to hydroxyl radicals ( . OH). Polylysine and histone H1 were labelled with SECCA, the succinimidyl ester of coumarin-3-carboxylic acid, which generates the fluorescent derivative 7-OH-SECCA following its interaction with radiation-induced . OH in aqueous solution. The fluorescence induced per unit γ-ray dose reflecting the accessibility of . OH to such SECCA-conjugated biomolecules was recorded. The biomolecules were also labelled with the fluorescent derivative 7-OH-SECCA in trace amounts to study their conformation under identical conditions via fluorescence polarization spectroscopy. (author)

Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses.

Science.gov (United States)

Vasconcelos, Maydla Dos Santos; Passos, Wilson Espíndola; Lescanos, Caroline Honaiser; Pires de Oliveira, Ivan; Trindade, Magno Aparecido Gonçalves; Caires, Anderson Rodrigues Lima; Muzzi, Rozanna Marques

2018-01-01

The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.). The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB) and ∼90% (RSLB). The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2), about 49%, and the oleic monounsaturated (18  :  1), ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3), ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses

Directory of Open Access Journals (Sweden)

Maydla dos Santos Vasconcelos

2018-01-01

Full Text Available The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.. The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB and ∼90% (RSLB. The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2, about 49%, and the oleic monounsaturated (18  :  1, ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3, ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

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.

4-Pyridoxic Acid in the Spent Dialysate: Contribution to Fluorescence and Optical Monitoring.

Science.gov (United States)

Kalle, Sigrid; Tanner, Risto; Arund, Jürgen; Tomson, Ruth; Luman, Merike; Fridolin, Ivo

2016-01-01

In this work we estimated the contribution of the fluorescence of 4-pyridoxic acid (4-PA) to the total fluorescence of spent dialysate with the aim of evaluating the on-line monitoring of removal of this vitamin B-6 metabolite from the blood of patients with end-stage renal disease (ESRD). Spectrofluorometric analysis of spent dialysate, collected from hemodialysis and hemodiafiltration sessions of 10 patients receiving regularly pyridoxine injections after dialysis treatment, was performed in the range of Ex/Em 220-500 nm. 4-PA in dialysate samples was identified and quantified using HPLC with fluorescent and MS/MS detection. Averaged HPLC chromatogram of spent dialysate had many peaks in the wavelength region of Ex320/Em430 nm where 4-PA was the highest peak with contribution of 42.2±17.0% at the beginning and 47.7±18.0% in the end of the dialysis. High correlation (R = 0.88-0.95) between 4-PA concentration and fluorescence intensity of spent dialysate was found in the region of Ex310-330/Em415-500 nm, respectively. 4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments.

4-Pyridoxic Acid in the Spent Dialysate: Contribution to Fluorescence and Optical Monitoring.

Directory of Open Access Journals (Sweden)

Sigrid Kalle

Full Text Available In this work we estimated the contribution of the fluorescence of 4-pyridoxic acid (4-PA to the total fluorescence of spent dialysate with the aim of evaluating the on-line monitoring of removal of this vitamin B-6 metabolite from the blood of patients with end-stage renal disease (ESRD.Spectrofluorometric analysis of spent dialysate, collected from hemodialysis and hemodiafiltration sessions of 10 patients receiving regularly pyridoxine injections after dialysis treatment, was performed in the range of Ex/Em 220-500 nm. 4-PA in dialysate samples was identified and quantified using HPLC with fluorescent and MS/MS detection.Averaged HPLC chromatogram of spent dialysate had many peaks in the wavelength region of Ex320/Em430 nm where 4-PA was the highest peak with contribution of 42.2±17.0% at the beginning and 47.7±18.0% in the end of the dialysis. High correlation (R = 0.88-0.95 between 4-PA concentration and fluorescence intensity of spent dialysate was found in the region of Ex310-330/Em415-500 nm, respectively.4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments.

Preparation of polymer-rare earth complex using salicylic acid-containing polystyrene and its fluorescence emission property

Energy Technology Data Exchange (ETDEWEB)

Gao Baojiao, E-mail: gaobaojiao@126.com [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Zhang Wei; Zhang Zhengguo; Lei Qingjuan [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China)

2012-08-15

Salicylic acid (SA) was first bonded onto the side chains of polystyrene (PS), obtaining functional macromolecule SAPS. Using the salicylic acid-containing polystyrene as a macromolecular ligand, a polymer-rare earth complex, SAPS-Eu(III), was prepared. The structure of SAPS-Eu(III) was characterized, and the fluorescence properties of SAPS-Eu(III) were mainly investigated. The experimental results show that the complex SAPS-Eu(III) has fine chemical stability because of the bidentate chelating effect of salicylic acid ligand. More important, the ligand SA on the side chains of PS can strongly sensitize the fluorescence emission of the center ion, Eu{sup 3+} ion, and it enables the complex SAPS-Eu(III) to produce the apparent 'Antenna Effect'. In the diluted solution of the functional macromolecule SAPS, the formed complex SAPS-Eu(III) belongs to an intramolecular complex, or an intrachain complex. For the binary intramolecular complex SAPS-Eu(III), the apparent saturated coordination number of SA of SAPS towards Eu{sup 3+} ion is equal to 10, and here the binary intrachain complex SAPS-Eu(III) has the strongest fluorescence emission. On this basis, small-molecule 1,10-phenanthroline (Phen) acting as a co-ligand is added and the ternary complex SAPS-Eu(III)-Phen will be formed. As long as a small amount of Phen is added (in the molar ratio 1:1 (n(Phen):n(Eu))), the coordination of the two kinds of ligands, SA of SAPS and Phen, to Eu{sup 3+} ion will reach complete saturation, and here the fluorescence emission of the ternary complex will be further enhanced via the complementary coordination effect in comparison with that of the binary complex SAPS-Eu(III). - Highlights: Black-Right-Pointing-Pointer We prepared the functional polystyrene, SAPS, on whose side chain salicylic acid ligand was bonded. Black-Right-Pointing-Pointer The polymer-rare earth complex, SAPS-Eu(III), was prepared and a stronger 'antenna effect' was produced. Black

Preparation of polymer–rare earth complex using salicylic acid-containing polystyrene and its fluorescence emission property

International Nuclear Information System (INIS)

Gao Baojiao; Zhang Wei; Zhang Zhengguo; Lei Qingjuan

2012-01-01

Salicylic acid (SA) was first bonded onto the side chains of polystyrene (PS), obtaining functional macromolecule SAPS. Using the salicylic acid-containing polystyrene as a macromolecular ligand, a polymer–rare earth complex, SAPS–Eu(III), was prepared. The structure of SAPS–Eu(III) was characterized, and the fluorescence properties of SAPS–Eu(III) were mainly investigated. The experimental results show that the complex SAPS–Eu(III) has fine chemical stability because of the bidentate chelating effect of salicylic acid ligand. More important, the ligand SA on the side chains of PS can strongly sensitize the fluorescence emission of the center ion, Eu 3+ ion, and it enables the complex SAPS–Eu(III) to produce the apparent “Antenna Effect”. In the diluted solution of the functional macromolecule SAPS, the formed complex SAPS–Eu(III) belongs to an intramolecular complex, or an intrachain complex. For the binary intramolecular complex SAPS–Eu(III), the apparent saturated coordination number of SA of SAPS towards Eu 3+ ion is equal to 10, and here the binary intrachain complex SAPS–Eu(III) has the strongest fluorescence emission. On this basis, small-molecule 1,10-phenanthroline (Phen) acting as a co-ligand is added and the ternary complex SAPS–Eu(III)–Phen will be formed. As long as a small amount of Phen is added (in the molar ratio 1:1 (n(Phen):n(Eu))), the coordination of the two kinds of ligands, SA of SAPS and Phen, to Eu 3+ ion will reach complete saturation, and here the fluorescence emission of the ternary complex will be further enhanced via the complementary coordination effect in comparison with that of the binary complex SAPS–Eu(III). - Highlights: ► We prepared the functional polystyrene, SAPS, on whose side chain salicylic acid ligand was bonded. ► The polymer-rare earth complex, SAPS–Eu(III), was prepared and a stronger “antenna effect” was produced. ► For the intramolecular complex SAPS–Eu(III), the apparent

A single pH fluorescent probe for biosensing and imaging of extreme acidity and extreme alkalinity.

Science.gov (United States)

Chao, Jian-Bin; Wang, Hui-Juan; Zhang, Yong-Bin; Li, Zhi-Qing; Liu, Yu-Hong; Huo, Fang-Jun; Yin, Cai-Xia; Shi, Ya-Wei; Wang, Juan-Juan

2017-07-04

A simple tailor-made pH fluorescent probe 2-benzothiazole (N-ethylcarbazole-3-yl) hydrazone (Probe) is facilely synthesized by the condensation reaction of 2-hydrazinobenzothiazole with N-ethylcarbazole-3-formaldehyde, which is a useful fluorescent probe for monitoring extremely acidic and alkaline pH, quantitatively. The pH titrations indicate that Probe displays a remarkable emission enhancement with a pK a of 2.73 and responds linearly to minor pH fluctuations within the extremely acidic range of 2.21-3.30. Interestingly, Probe also exhibits strong pH-dependent characteristics with pK a 11.28 and linear response to extreme-alkalinity range of 10.41-12.43. In addition, Probe shows a large Stokes shift of 84 nm under extremely acidic and alkaline conditions, high selectivity, excellent sensitivity, good water-solubility and fine stability, all of which are favorable for intracellular pH imaging. The probe is further successfully applied to image extremely acidic and alkaline pH values fluctuations in E. coli cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Unlocked Nucleic Acids with a Pyrene-Modified Uracil: Synthesis, Hybridization Studies, Fluorescent Properties and i-Motif Stability

Czech Academy of Sciences Publication Activity Database

Perlíková, Pavla; Karlsen, K. K.; Pedersen, E. B.; Wengel, J.

2014-01-01

Roč. 15, č. 1 (2014), s. 146-156 ISSN 1439-4227 Grant - others:European Research Council(XE) FP7-268776 Institutional support: RVO:61388963 Keywords : fluorescence * i-motifs * nucleic acid hybridization * oligonucleotides * unlocked nucleic acids Subject RIV: CE - Biochemistry Impact factor: 3.088, year: 2014

Rapid fluorometric determination of perfluorooctanoic acid by its quenching effect on the fluorescence of quantum dots

Energy Technology Data Exchange (ETDEWEB)

Liu, Qi; Huang, Aizhen; Wang, Nan, E-mail: nwang@hust.edu.cn; Zheng, Guan; Zhu, Lihua

2015-05-15

Analysis of perfluorooctanoic acid (PFOA) usually requires a combination of high-performance liquid chromatography and mass spectrometry, which is expensive and time-consuming. In the present work, water-soluble CdS quantum dots (QDs) were employed to develop a simple and rapid fluorometric method for the determination of PFOA. Strongly fluorescent CdS QDs were prepared by using 3-mercaptopropionic acid (MPA) as a stabilizer. It was observed that PFOA strongly quenched the fluorescence emission of the MPA-CdS QDs because PFOA promotes the aggregation of MPA-CdS QDs through a fluorine–fluorine affinity interaction. Under optimum conditions, the fluorescence intensity of MPA-CdS QDs was observed to decrease linearly with an increase in the concentration of PFOA from 0.5 to 40 μmol L{sup −1}, with a limit of detection of 0.3 μmol L{sup −1}. This new method was successfully implemented for the analysis of PFOA-spiked textile samples, with recoveries ranging from 95% to 113%. - Highlights: • PFOA significantly quenched the fluorescence emission of quantum dots (QDs). • A rapid and simple fluorescence sensor was proposed for determining PFOA by QDs. • PFOA determination could be completed within approximately 10 min. • The developed method had a working range of 0.5 to 40 μmol L{sup −1} and a detection limit of 0.3 μmol L{sup −1}.

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...

Fluorescence Quenching of Humic Acid by Coated Metallic Silver Particles.

Science.gov (United States)

Zhu, Guocheng; Yin, Jun

2017-07-01

Natural organic matter is an important component of the aquatic environments, which has attracted wide attention to its influence of interaction with other pollutants. The present work aimed to investigate its fluorescence quenching (FQ) by coated metallic silver particles (AgNPs). In this work, using fluorescence spectroscopy in conjunction with UV-Vis spectroscopy and dynamic light scattering, the effect of coated AgNPs on fluorescence quenching intensity (FQI) of humic acid (HA) was assessed. In addition, the influence of electrolytes (NaCl, NaNO 3 and CaNO 3 ) in the FQI was observed. Results showed that with AgNPs dosage increased (>1.17X10 -3  mM), fluorescence quantum yield of HA gradually decreased, which implies that the FQ occurred. Furher observation showed that the FQ process followed both first-order and second-order Stern-Volmer functions. The FQ process was affected by the electrolytes: NaCl had an effect on reduction of FQI, possibly resulting from dissolution of AgNPs; Both of NaNO 3 and Ca(NO 3 ) 2 had an effect on the FQ of HA but Ca(NO 3 ) 2 presented greater degree. As a result, the FQ degree of HA by alone electrolyte was listed in descent order as Ca(NO 3 ) 2  > NaNO 3  > NaCl, which also implies the subsequent experimental results, indicating the FQ degree of HA by mutual electrolytes as Ca(NO 3 ) 2  + NaNO 3  > Ca(NO 3 ) 2  + NaCl > NaNO 3  + NaCl.

A benzothiazole-based fluorescent probe for hypochlorous acid detection and imaging in living cells

Science.gov (United States)

Nguyen, Khac Hong; Hao, Yuanqiang; Zeng, Ke; Fan, Shengnan; Li, Fen; Yuan, Suke; Ding, Xuejing; Xu, Maotian; Liu, You-Nian

2018-06-01

A benzothiazole-based turn-on fluorescent probe with a large Stokes shift (190 nm) has been developed for hypochlorous acid detection. The probe displays prompt fluorescence response for HClO with excellent selectivity over other reactive oxygen species as well as a low detection limit of 0.08 μM. The sensing mechanism involves the HClO-induced specific oxidation of oxime moiety of the probe to nitrile oxide, which was confirmed by HPLC-MS technique. Furthermore, imaging studies demonstrated that the probe is cell permeable and can be applied to detect HClO in living cells.

Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.

Science.gov (United States)

Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

2016-07-05

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane.

Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

Science.gov (United States)

Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

2016-01-01

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

Enhanced fluorescence of Tb(III), Dy(III) perchlorate by salicylic acid in bis(benzoylmethyl) sulfoxide complexes and luminescence mechanism

International Nuclear Information System (INIS)

Li Wenxian; Zheng Yushan; Sun Xiaojun; Chai Wenjuan; Ren Tie; Shi Xiaoyan

2010-01-01

Two novel ternary rare earth perchlorate complexes had been synthesized by using bis(benzoylmethyl) sulfoxide as first ligand (L=C 6 H 5 COCH 2 SOCH 2 COC 6 H 5 ), salicylic acid as second ligand (L ' =C 6 H 4 OHCOO - ). The compounds were characterized by elemental analysis, TG-DSC and molar conductivities in DMF solution. The composition was suggested as [REL 5 L'](ClO 4 ) 2 .nH 2 O (RE=Tb, Dy; n=6, 8 ). Based on IR, 1 HNMR and UV spectra, it showed that the first ligand, bis(benzoylmethyl) sulfoxide (L), bonded with Tb(III), Dy(III) ions by the oxygen atom of sulfinyl group. The second ligand, salicylic acid group (L'), not only bonded with RE(III) ions by one oxygen atom of carboxyl group but also bonded with RE(III) ions by oxygen atom of phenolic hydroxyl group. In bis(benzoylmethyl) sulfoxide system, fluorescent spectra of the complexes showed that the luminescence of Tb(III), Dy(III) ions was enhanced by the second ligand salicylic acid. The ternary complexes had stronger fluorescence than the binary ones where only bis(benzoylmethyl) sulfoxide acted as ligand. Phosphorescent spectra of the two ligands indicated that the coordination of salicylic acid resulted in the matching extent increasing between the triplet state of ligand and excited state of the rare earths. The relationship between fluorescence lifetime and fluorescence intensity was also discussed.

Antimicrobial evaluation of novel poly-lactic acid based nanocomposites incorporated with bioactive compounds in-vitro and in refrigerated vacuum-packed cooked sausages.

Science.gov (United States)

Rezaeigolestani, Mohammadreza; Misaghi, Ali; Khanjari, Ali; Basti, Afshin Akhondzadeh; Abdulkhani, Ali; Fayazfar, Samira

2017-11-02

Biodegradability and antimicrobial activity of food packaging materials are among the most attractive parameters in modern food industries. In order to develop biodegradable poly-lactic acid (PLA) film to antibacterial nanocomposites, different concentration of Zataria multiflora Bioss. essential oil (ZME), propolis ethanolic extract (PEE) and cellulose nanofiber (CNF) were incorporated to the polymer by solvent casting method. The resulting films were characterized by mechanical and physical tests and their antimicrobial application was evaluated in-vitro against four common foodborne pathogens and in vacuum-packed cooked sausages during refrigerated storage. Mechanical examination revealed that addition of ZME and PEE made films more flexible and incorporation of CNF improved almost all mechanical parameters tested. Moreover, according to physical analysis, incorporation of 0.5% v/v ZME to the composite primary solutions improved water vapor permeability of the resulting films. Almost all of the active films were effective against the tested bacteria except for PLA/PEE films, and maximum antibacterial effects recorded for the films containing both ZME and PEE. Based on the microbiological and sensory evaluation of the sausages, all of the PLA/1%ZME/PEE composites increased the shelf life to >40days. The results indicate that incorporation of natural antimicrobial substances such as ZME and PEE to packaging material could be an interesting approach in development of active packaging material without significant negative effect on polymer technical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanical and moisture barrier properties of titanium dioxide nanoparticles and halloysite nanotubes reinforced polylactic acid (PLA)

International Nuclear Information System (INIS)

Alberton, J; Martelli, S M; Soldi, V; Fakhouri, F M

2014-01-01

Polylactic acid (PLA) has been larger used in biomedical field due to its low toxicity and biodegradability. The aim of this study was to produce PLLA nanocomposites, by melt extrusion, containing Halloysite nanotubes (HNT) and/or titanium dioxide (TiO 2 ) nanoparticles. Immediately after drying, PLLA was mechanically homogenized with the nanofillers and then melt blended using a single screw extruder (L/D = 30) at a speed of 110 rpm, with three heating zones in which the following temperatures were maintained: 150, 150 and 160°C (AX Plasticos model AX14 LD30). The film samples were obtained by compression molding in a press with a temperature profile of 235 ± 5°C for 2.5 min, after pressing, films were cooled up to room temperature. The mechanical tests were performed according to ASTM D882-09 and the water vapor permeability (WVP) was measured according to ASTM E-96, in triplicate. The tensile properties indicated that the modulus was improved with increased TiO 2 content up to 1g/100g PLLA. The Young's modulus (YM) of the PLA was increased from 3047 MPa to 3222 MPa with the addition of 1g TiO 2 /100g PLLA. The tensile strength (TS) of films increases with the TiO 2 content. In both cases, the YM and TS are achieved at the 1% content of TiO 2 and is due to the reinforcing effect of nanoparticles. Pristine PLA showed a strain at break (SB) of 3.56%, while the SB of nanocomposites were significant lower, for instance the SB of composite containing 7.5 g HNT/100g PLLA was around 1.90 %. The WVP of samples was increased by increasing the nano filler content. It should be expected that an increase of nanofiller content would decrease the mass transfer of water molecules throughout the samples due to the increase in the way water molecules will have to cross to permeate the material. However, this was not observed. Therefore, this result can be explained considering the molecular structure of both fillers, which contain several hydroxyl groups in the surface

Effect of phosphate-based glass fibre surface properties on thermally produced poly(lactic acid) matrix composites.

Science.gov (United States)

Mohammadi, Maziar Shah; Ahmed, Ifty; Muja, Naser; Rudd, Christopher D; Bureau, Martin N; Nazhat, Showan N

2011-12-01

Incorporation of soluble bioactive glass fibres into biodegradable polymers is an interesting approach for bone repair and regeneration. However, the glass composition and its surface properties significantly affect the nature of the fibre-matrix interface and composite properties. Herein, the effect of Si and Fe on the surface properties of calcium containing phosphate based glasses (PGs) in the system (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x = 0, 5 and 10 mol.%) were investigated. Contact angle measurements revealed a higher surface energy, and surface polarity as well as increased hydrophilicity for Si doped PG which may account for the presence of surface hydroxyl groups. Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibres and randomly incorporated into poly(lactic acid) (PLA) produced by melt processing. The ageing in deionised water (DW), mechanical property changes in phosphate buffered saline (PBS) and cytocompatibility properties of these composites were investigated. In contrast to Fe10 and as a consequence of the higher surface energy and polarity of Fe5Si5, its incorporation into PLA led to increased inorganic/organic interaction indicated by a reduction in the carbonyl group of the matrix. PLA chain scission was confirmed by a greater reduction in its molecular weight in PLA-Fe5Si5 composites. In DW, the dissolution rate of PLA-Fe5Si5 was significantly higher than that of PLA-Fe10. Dissolution of the glass fibres resulted in the formation of channels within the matrix. Initial flexural strength was significantly increased through PGF incorporation. After PBS ageing, the reduction in mechanical properties was greater for PLA-Fe5Si5 compared to PLA-Fe10. MC3T3-E1 preosteoblasts seeded onto PG discs, PLA and PLA-PGF composites were evaluated for up to 7 days indicating that the materials were generally cytocompatible. In addition, cell alignment along the PGF

Safety Evaluation of a Bioglass–Polylactic Acid Composite Scaffold Seeded with Progenitor Cells in a Rat Skull Critical-Size Bone Defect

Science.gov (United States)

El-Kady, Abeer M.; Arbid, Mahmoud S.; Abd El-Hady, Bothaina M.; Marzi, Ingo; Seebach, Caroline

2014-01-01

Treating large bone defects represents a major challenge in traumatic and orthopedic surgery. Bone tissue engineering provides a promising therapeutic option to improve the local bone healing response. In the present study tissue biocompatibility, systemic toxicity and tumorigenicity of a newly developed composite material consisting of polylactic acid (PLA) and 20% or 40% bioglass (BG20 and BG40), respectively, were analyzed. These materials were seeded with mesenchymal stem cells (MSC) and endothelial progenitor cells (EPC) and tested in a rat calvarial critical size defect model for 3 months and compared to a scaffold consisting only of PLA. Serum was analyzed for organ damage markers such as GOT and creatinine. Leukocyte count, temperature and free radical indicators were measured to determine the degree of systemic inflammation. Possible tumor occurrence was assessed macroscopically and histologically in slides of liver, kidney and spleen. Furthermore, the concentrations of serum malondialdehyde (MDA) and sodium oxide dismutase (SOD) were assessed as indicators of tumor progression. Qualitative tissue response towards the implants and new bone mass formation was histologically investigated. BG20 and BG40, with or without progenitor cells, did not cause organ damage, long-term systemic inflammatory reactions or tumor formation. BG20 and BG40 supported bone formation, which was further enhanced in the presence of EPCs and MSCs. This investigation reflects good biocompatibility of the biomaterials BG20 and BG40 and provides evidence that additionally seeding EPCs and MSCs onto the scaffold does not induce tumor formation. PMID:24498345

Fluorescence ON–OFF switching using micelle of stimuli-responsive double hydrophilic block copolymers: Nile Red fluorescence in micelles of poly(acrylic acid-b-N-isopropylacrylamide)

Energy Technology Data Exchange (ETDEWEB)

Yee, Min Min; Tsubone, Miyabi; Morita, Takuya [Department of Chemistry, Graduate School of Science & Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan); Yusa, Shin-ichi [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji 671-2280 (Japan); Nakashima, Kenichi, E-mail: nakashik@cc.saga-u.ac.jp [Department of Chemistry, Graduate School of Science & Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan)

2016-08-15

The dual-mode fluorescence ON–OFF switching of Nile Red (NR) by using stimuli-responsive polymeric micelle of poly(acrylic acid-b-N-isopropylacrylamide) (PAA-b-PNIPAM) has been studied. PAA-b-PNIPAM, one of double hydrophilic block copolymers, is known to form PNIPAM-core/PAA-corona micelles in aqueous solutions when the temperature of the solution is elevated up to the lower critical solution temperature (LCST) of PNIPAM block. It also forms PAA-core/PNIPAM-corona micelles when the anionic PAA block is charge-neutralized with cationic cetyltrimethylammonium ion. Fluorescence properties of NR in the micelles are elucidated by observing various fluorescence parameters such as intensity, polarization, and quantum yield. It is found that the fluorescence intensity is negligibly low (OFF-state) when PAA-b-PNIPAM exists as a form of unimer, whereas it is remarkably enhanced (ON-state) when the PNIPAM-core or PAA-core micelles are formed. These results demonstrate that a novel fluorescence ON–OFF switching system can be constructed by using PAA-b-PNIPAM micelles and NR.

Antimicrobial activity of lauric arginate-coated polylactic acid films against Listeria monocytogenes and Salmonella typhimurium on cooked sliced ham.

Science.gov (United States)

Theinsathid, Pornpun; Visessanguan, Wonnop; Kruenate, Jittiporn; Kingcha, Yutthana; Keeratipibul, Suwimon

2012-02-01

A novel type of environmentally friendly packaging with antibacterial activity was developed from lauric arginate (LAE)-coating of polylactic acid (PLA) films after surface activation using a corona discharge. Scanning electron microscopy (SEM)-based analysis of the LAE/PLA films confirmed the successful coating of LAE on the PLA surface. The mechanical properties of the LAE/PLA films with different levels of LAE-coating (0% to 2.6%[w/w]) were essentially the same as those of the neat PLA film. The antibacterial activity of the LAE/PLA films against Listeria monocytogenes and Salmonella enterica Serovar Typhimurium (S. Typhimurium) was confirmed by a qualitative modified agar diffusion assay and quantitative JIS Z 2801:2000 method. Using the LAE/PLA film as a food-contact antimicrobial packaging for cooked cured ham, as a model system, suggested a potential application to inhibit L. monocytogenes and S. Typhimurium on ham with a 0.07% (w/w) LAE coating on the PLA when high transparency is required, as evidenced from the 2 to 3 log CFU/tested film lower pathogen growth after 7 d storage but even greater antibacterial activity is obtained with a LAE coating level of 2.6% (w/w) but at the cost of a reduced transparency of the finished product. This article shows how we can simply develop functional green packaging of PLA for food with effective and efficient antimicrobial activity by use of LAE coating on the surface via corona discharge. The effectiveness of an innovative antimicrobial LAE-coated PLA film against foodborne pathogens was demonstrated. Importantly, the application of the LAE to form the LAE-coated PLA film can be customized within current film manufacturing lines. © 2012 Institute of Food Technologists®

High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T., E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2015-03-30

Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

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.

Enantioselective micellar electrokinetic chromatography of dl-amino acids using (+)-1-(9-fluorenyl)-ethyl chloroformate derivatization and UV-induced fluorescence detection.

Science.gov (United States)

Prior, Amir; van de Nieuwenhuijzen, Erik; de Jong, Gerhardus J; Somsen, Govert W

2018-05-22

Chiral analysis of dl-amino acids was achieved by micellar electrokinetic chromatography coupled with UV-excited fluorescence detection. The fluorescent reagent (+)-1-(9-fluorenyl)ethyl chloroformate was employed as chiral amino acid derivatizing agent and sodium dodecyl sulfate served as pseudo-stationary phase for separating the formed amino acid diastereomers. Sensitive analysis of (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids was achieved applying a xenon-mercury lamp for ultraviolet excitation, and a spectrograph and charge-coupled device for wavelength-resolved emission detection. Applying signal integration over a 30-nm emission wavelength interval, signal-to-noise ratios for derivatized amino acids were up to 23 times higher as obtained using a standard photomultiplier for detection. The background electrolyte composition (electrolyte, pH, sodium dodecyl sulfate concentration, and organic solvent) was studied in order to attain optimal chemo- and enantioseparation. Enantioseparation of twelve proteinogenic dl-amino acids was achieved with chiral resolutions between 1.2 and 7.9, and detection limits for most derivatized amino acids in the 13-60 nM range (injected concentration). Linearity (coefficients of determination > 0.985) and peak-area and migration-time repeatabilities (relative standard deviations lower than 2.6 and 1.9%, respectively) were satisfactory. The employed fluorescence detection system provided up to 100-times better signal-to-noise ratios for (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids than ultraviolet absorbance detection, showing good potential for d-amino acid analysis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

Science.gov (United States)

Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

2018-05-01

A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

Structure of the human-heart fatty-acid-binding protein 3 in complex with the fluorescent probe 1-anilinonaphthalene-8-sulphonic acid

Energy Technology Data Exchange (ETDEWEB)

Hirose, Mika; Sugiyama, Shigeru, E-mail: sugiyama@chem.eng.osaka-u.ac.jp [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Ishida, Hanako; Niiyama, Mayumi [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 2-1 Yamadaoka, Suita 565-0871 (Japan); Matsuoka, Daisuke; Hara, Toshiaki [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Mizohata, Eiichi [Osaka University, 2-1 Yamadaoka, Suita 565-0871 (Japan); Murakami, Satoshi [Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagaw 226-8501 (Japan); Inoue, Tsuyoshi [Osaka University, 2-1 Yamadaoka, Suita 565-0871 (Japan); Matsuoka, Shigeru; Murata, Michio [Lipid Active Structure Project, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan); Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043 (Japan)

2013-11-01

The crystal structure of human-heart-type fatty-acid-binding protein in complex with anilinonaphthalene-8-sulfonate was solved at 2.15 Å resolution revealing the detailed binding mechanism of the fluorescent probe 1-anilinonaphthalene-8-sulfonate. Heart-type fatty-acid-binding protein (FABP3), which is a cytosolic protein abundantly found in cardiomyocytes, plays a role in trafficking fatty acids throughout cellular compartments by reversibly binding intracellular fatty acids with relatively high affinity. The fluorescent probe 1-anilinonaphthalene-8-sulfonate (ANS) is extensively utilized for examining the interaction of ligands with fatty-acid-binding proteins. The X-ray structure of FABP3 was determined in the presence of ANS and revealed the detailed ANS-binding mechanism. Furthermore, four water molecules were clearly identified in the binding cavity. Through these water molecules, the bound ANS molecule forms indirect hydrogen-bond interactions with FABP3. The adipocyte-type fatty-acid-binding protein (FABP4) exhibits 67% sequence identity with FABP3 and its crystal structure is almost the same as that of FABP3. However, FABP4 can bind with a higher affinity to ANS than FABP3. To understand the difference in their ligand specificities, a structural comparison was performed between FABP3–ANS and FABP4–ANS complexes. The result revealed that the orientation of ANS binding to FABP3 is completely opposite to that of ANS binding to FABP4, and the substitution of valine in FABP4 to leucine in FABP3 may result in greater steric hindrance between the side-chain of Leu115 and the aniline ring of ANS.

Structure of the human-heart fatty-acid-binding protein 3 in complex with the fluorescent probe 1-anilinonaphthalene-8-sulphonic acid

International Nuclear Information System (INIS)

Hirose, Mika; Sugiyama, Shigeru; Ishida, Hanako; Niiyama, Mayumi; Matsuoka, Daisuke; Hara, Toshiaki; Mizohata, Eiichi; Murakami, Satoshi; Inoue, Tsuyoshi; Matsuoka, Shigeru; Murata, Michio

2013-01-01

The crystal structure of human-heart-type fatty-acid-binding protein in complex with anilinonaphthalene-8-sulfonate was solved at 2.15 Å resolution revealing the detailed binding mechanism of the fluorescent probe 1-anilinonaphthalene-8-sulfonate. Heart-type fatty-acid-binding protein (FABP3), which is a cytosolic protein abundantly found in cardiomyocytes, plays a role in trafficking fatty acids throughout cellular compartments by reversibly binding intracellular fatty acids with relatively high affinity. The fluorescent probe 1-anilinonaphthalene-8-sulfonate (ANS) is extensively utilized for examining the interaction of ligands with fatty-acid-binding proteins. The X-ray structure of FABP3 was determined in the presence of ANS and revealed the detailed ANS-binding mechanism. Furthermore, four water molecules were clearly identified in the binding cavity. Through these water molecules, the bound ANS molecule forms indirect hydrogen-bond interactions with FABP3. The adipocyte-type fatty-acid-binding protein (FABP4) exhibits 67% sequence identity with FABP3 and its crystal structure is almost the same as that of FABP3. However, FABP4 can bind with a higher affinity to ANS than FABP3. To understand the difference in their ligand specificities, a structural comparison was performed between FABP3–ANS and FABP4–ANS complexes. The result revealed that the orientation of ANS binding to FABP3 is completely opposite to that of ANS binding to FABP4, and the substitution of valine in FABP4 to leucine in FABP3 may result in greater steric hindrance between the side-chain of Leu115 and the aniline ring of ANS

Determination of aristolochic acids by high-performance liquid chromatography with fluorescence detection.

Science.gov (United States)

Wang, Yinan; Chan, Wan

2014-06-25

Nephrotoxic and carcinogenic aristolochic acids (AAs) are naturally occurring nitrophenanthrene carboxylic acids in the herbal genus Aristolochia. The misuse of AA-containing herbs in preparing slimming drugs has caused hundred of cases of kidney disease in Belgium women in a slimming regime in the early 1990s. Accumulating evidence also suggested that prolong dietary intake of AA-contaminated food is one of the major causes to the Balkan endemic nephropathy that was first observed in the late 1950s. Therefore, analytical methods of high sensitivity are extremely important for safeguarding human exposure to AA-containing herbal medicines, herbal remedies, and food composites. In this paper, we describe the development of a new high-performance liquid chromatography coupled fluorescence detector (HPLC-FLD) method for the sensitive determination of AAs. The method makes use of a novel cysteine-induced denitration reaction that "turns on" the fluorescence of AAs for fluorometric detections. Our results showed that the combination of cysteine-induced denitration and HPLC-FLD analysis allows for sensitive quantification of AA-I and AA-II at detection limits of 27.1 and 25.4 ng/g, respectively. The method was validated and has been successfully applied in quantifying AAs in Chinese herbal medicines.

生物质与聚乳酸共热解行为及其动力学研究%Thermal decomposition and kinetics of mixtures of polylactic acid and biomass during copyrolysis

Institute of Scientific and Technical Information of China (English)

王刚; 李爱民

2008-01-01

Thermal decomposition of polylactic acid (PLA) was studied in the presence of pine wood sawdust (PS), walnut shell (WS), corncob (CC) in order to understand the pyrolytic behavior of these components occurring in waste. A thermogravimetric analyzer (TGA) was applied for monitoring the mass loss profiles under heating rate of 10℃·min-1. Results obtained from this comprehensive investigation indicated that PLA was decomposed in the temperature range 300-372℃, whereas the thermal degradation temperature of biomass is 183-462℃. The difference of mass loss (△W) between experimental and theoretical ones, calculated as algebraic sums of those from each separated component, is about 17% 46% at 300-400℃. These experimental results indicated a significant syner-gistic effect during PLA and biomass copyrolysis. Moreover, a kinetic analysis was performed to fit thermogravimetric data, the global processes being considered as one to two consecutive reactions. A reasonable fit to the experimental data was obtained for all materials and their blends.

Effect of Nitric Acid on the Low Fluorescing Performance of Drilling Fluid Lubricant Based Animal and Vegetable Oils

Directory of Open Access Journals (Sweden)

Feng-shan Zhou

2013-01-01

Full Text Available After synthesis of mixed fatty acid triethanolamine ester surfactant based on animal and vegetable mixed oils, the reaction solution was added into 4% (wt/wt liquid nitric acid or 9% (wt/wt solid nitric acid as eliminating fluorescent agent continuing to react from 1 to 2 hours. The low fluorescence lubricant named E167 for drilling fluid was prepared, in which maximum fluorescence intensity (Fmax was less than 10 in three-dimensional fluorescence spectra of excitation wavelength range. When the E167 was added into fresh water based drilling fluid at the dosage of 0.5% (wt/wt, the sticking coefficient reduced rate (ΔKf is 78% and the extreme pressure (E-P friction coefficient reduced rate (Δf is 79%. In the case of 4% brine mud with 0.5% (wt/wt E167 in it, the ΔKf and Δf are 75% and 62%, respectively. After the hot rolling ageing test 180°C × 16 h with the E167 was added into fresh water based drilling fluid at the dosage of 1% (wt/wt, the ΔKf and Δf are greater than 70%, which shows a much better lubrication properties of strong resistance to high temperature. The fresh water based drilling fluid which contains 1% (wt/wt E167 is almost nonfoaming even after hot rolling ageing 120°C × 16 h.

Chromophore Structure of Photochromic Fluorescent Protein Dronpa: Acid-Base Equilibrium of Two Cis Configurations.

Science.gov (United States)

Higashino, Asuka; Mizuno, Misao; Mizutani, Yasuhisa

2016-04-07

Dronpa is a novel photochromic fluorescent protein that exhibits fast response to light. The present article is the first report of the resonance and preresonance Raman spectra of Dronpa. We used the intensity and frequency of Raman bands to determine the structure of the Dronpa chromophore in two thermally stable photochromic states. The acid-base equilibrium in one photochromic state was observed by spectroscopic pH titration. The Raman spectra revealed that the chromophore in this state shows a protonation/deprotonation transition with a pKa of 5.2 ± 0.3 and maintains the cis configuration. The observed resonance Raman bands showed that the other photochromic state of the chromophore is in a trans configuration. The results demonstrate that Raman bands selectively enhanced for the chromophore yield valuable information on the molecular structure of the chromophore in photochromic fluorescent proteins after careful elimination of the fluorescence background.

Simultaneous determination of Magnolol and Honokiol by amino acid ionic liquid synchronous fluorescence spectrometry

Science.gov (United States)

Liu, Wei; Zhu, Xiashi

2018-05-01

A novel method based on amino acid ionic liquids (AAILs) as an additive synchronous fluorescence spectrometry is proposed for simultaneous determination of magnolol (MN) and honokiol (HN) in traditional Chinese medicine Houpu. The overlapping fluorescence spectrum of MN and HN could be completely separated in the AAILs medium. Experiment parameters (the type and concentration of AAILs, pH values and temperature) were discussed. The detection limits of MN and HN reached 1.46 ng/mL, 0.92 ng/mL and the recovery rates ranged from 98.6%-100.7%, 99.7%-100.6%, respectively. This methods was successfully employed for simultaneously determination of MN and HN in real samples. No significant differences could be found in the results of this method and the pharmacopoeia of People's Republic of China 2015 (Ch.P.2015). The experiment mechanisms were discussed by the Gaussian simulation and fluorescence quantum yield.

Preparation of dual-responsive hybrid fluorescent nano probe based on graphene oxide and boronic acid/BODIPY-conjugated polymer for cell imaging

Energy Technology Data Exchange (ETDEWEB)

Khoerunnisa [Department of IT Convergence, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); Kang, Eun Bi [Department of Chemical and Biological Engineering, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); Mazrad, Zihnil Adha Islamy [Department of IT Convergence, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); Lee, Gibaek [Department of Chemical and Biological Engineering, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); In, Insik [Department of IT Convergence, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); Department of Polymer Science and Engineering, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); Park, Sung Young, E-mail: parkchem@ut.ac.kr [Department of IT Convergence, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of); Department of Chemical and Biological Engineering, Korea National University of Transportation, Chungju 380–702 (Korea, Republic of)

2017-02-01

Here, we report a pH- and thermo-responsive fluorescent nanomaterial of functionalized reduced graphene oxide (rGO) with cross-linked polymer produced via catechol-boronate diol binding mechanism. When conjugated with the hydrophobic dye boron dipyrromethane (BODIPY), this material can act as a dual-responsive nanoplatform for cells imaging. 2-Chloro-3′,4′-dihydroxyacetophenone (CCDP)-quaternized-poly(dimethylaminoethyl methacrylate-co-N-isopropylacrylamide) [C-PDN] was cross-linked with BODIPY and 4-chlorophenyl boronic acid (BA)-quaternized-poly(ethylene glycol)-g-poly(dimethylaminoethyl methacrylate-co-N-isopropylacrylamide) [BB-PPDN]. The GO was then reduced by the catechol group in the cross-linked polymer to synthesize rGO nanoparticles, which able to stabilize the quenching mechanism. This nanoplatform exhibits intense fluorescence at acidic pH and low fluorescence at physiological pH. Confocal laser scanning microscopy (CLSM) images shows bright fluorescence at lysosomal pH and total quench at physiological pH. Therefore, we have successfully developed a promising sensitive bio-imaging probe for identifying cancer cells. - Graphical abstract: [BB-PPDN]-[C-PDN]/rGO nanoparticles with boronic acid-catechol cis-diol binding mechanism toward change in pH demonstrated good biocompatibility and effective quenching for cancer cell detection. - Highlights: • Dual responsive (pH- and thermo) fluorescent nano probe was proposed for cells imaging. • The mechanism was based on cis-diol binding mechanism of boronic acid and catechol. • Reduced graphene oxide was used as quencher on nano-platform. • Detection was controlled dependent on pH based on diol compound of boron chemistry.

Biological conduits combining bone marrow mesenchymal stem cells and extracellular matrix to treat long-segment sciatic nerve defects

Directory of Open Access Journals (Sweden)

Yang Wang

2015-01-01

Full Text Available The transplantation of polylactic glycolic acid conduits combining bone marrow mesenchymal stem cells and extracellular matrix gel for the repair of sciatic nerve injury is effective in some respects, but few data comparing the biomechanical factors related to the sciatic nerve are available. In the present study, rabbit models of 10-mm sciatic nerve defects were prepared. The rabbit models were repaired with autologous nerve, a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells, or a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel. After 24 weeks, mechanical testing was performed to determine the stress relaxation and creep parameters. Following sciatic nerve injury, the magnitudes of the stress decrease and strain increase at 7,200 seconds were largest in the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel group, followed by the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells group, and then the autologous nerve group. Hematoxylin-eosin staining demonstrated that compared with the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells group and the autologous nerve group, a more complete sciatic nerve regeneration was found, including good myelination, regularly arranged nerve fibers, and a completely degraded and resorbed conduit, in the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel group. These results indicate that bridging 10-mm sciatic nerve defects with a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel construct increases the stress relaxation under a constant strain, reducing anastomotic tension. Large elongations under a constant physiological load can limit the anastomotic opening and shift, which is beneficial for the regeneration and functional reconstruction of sciatic nerve. Better

Terbium fluorescence as a sensitive, inexpensive probe for UV-induced damage in nucleic acids

International Nuclear Information System (INIS)

El-Yazbi, Amira F.; Loppnow, Glen R.

2013-01-01

Graphical abstract: -- Highlights: •Simple, inexpensive, mix-and-read assay for positive detection of DNA damage. •Recognition of undamaged DNA via hybridization to a hairpin probe. •Terbium(III) fluorescence reports the amount of damage by binding to ssDNA. •Tb/hairpin is a highly selective and sensitive fluorescent probe for DNA damage. -- Abstract: Much effort has been focused on developing methods for detecting damaged nucleic acids. However, almost all of the proposed methods consist of multi-step procedures, are limited, require expensive instruments, or suffer from a high level of interferences. In this paper, we present a novel simple, inexpensive, mix-and-read assay that is generally applicable to nucleic acid damage and uses the enhanced luminescence due to energy transfer from nucleic acids to terbium(III) (Tb 3+ ). Single-stranded oligonucleotides greatly enhance the Tb 3+ emission, but duplex DNA does not. With the use of a DNA hairpin probe complementary to the oligonucleotide of interest, the Tb 3+ /hairpin probe is applied to detect ultraviolet (UV)-induced DNA damage. The hairpin probe hybridizes only with the undamaged DNA. However, the damaged DNA remains single-stranded and enhances the intrinsic fluorescence of Tb 3+ , producing a detectable signal directly proportional to the amount of DNA damage. This allows the Tb 3+ /hairpin probe to be used for sensitive quantification of UV-induced DNA damage. The Tb 3+ /hairpin probe showed superior selectivity to DNA damage compared to conventional molecular beacons probes (MBs) and its sensitivity is more than 2.5 times higher than MBs with a limit of detection of 4.36 ± 1.2 nM. In addition, this probe is easier to synthesize and more than eight times cheaper than MBs, which makes its use recommended for high-throughput, quantitative analysis of DNA damage

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

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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.

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.

Demonstration of the lack of cytotoxicity of unmodified and folic acid modified graphene oxide quantum dots, and their application to fluorescence lifetime imaging of HaCaT cells.

Science.gov (United States)

Goreham, Renee V; Schroeder, Kathryn L; Holmes, Amy; Bradley, Siobhan J; Nann, Thomas

2018-01-24

The authors describe the synthesis of water-soluble and fluorescent graphene oxide quantum dots via acid exfoliation of graphite nanoparticles. The resultant graphene oxide quantum dots (GoQDs) were then modified with folic acid. Folic acid receptors are overexpressed in cancer cells and hence can bind to functionalized graphene oxide quantum dots. On excitation at 305 nm, the GoQDs display green fluorescence with a peak wavelength at ~520 nm. The modified GoQDs are non-toxic to macrophage cells even after prolonged exposure and high concentrations. Fluorescence lifetime imaging and multiphoton microscopy was used (in combination) to image HeCaT cells exposed to GoQDs, resulting in a superior method for bioimaging. Graphical abstract Schematic representation of graphene oxide quantum dots, folic acid modified graphene oxide quantum dots (red), and the use of fluorescence lifetime to discriminate against green auto-fluorescence of HeCaT cells.

Assisted Interpretation of Laser-Induced Fluorescence Spectra of Egg-Based Binding Media Using Total Emission Fluorescence Spectroscopy

International Nuclear Information System (INIS)

Anglos, D.; Nevin, A.

2006-01-01

Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to auto fluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total emission fluorescence spectra where a series of consecutive emission spectra are recorded over a specific range. Results using nanosecond UV laser sources for LIF of egg-based binding media are presented which are rationalised following comparisons with total emission spectra. Specifically, fluorescence is assigned to tryptophan and oxidation products of amino acids; in the case of egg yolk, fatty-acid polymerisation and age-related degradation products account for the formation of fluorophores.

Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity.

Science.gov (United States)

Qi, Zewan; Chen, Yang

2017-01-15

Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb 3+ ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H + is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb 3+ . The long luminescence lifetime of Tb 3+ allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H + in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands. Copyright © 2016 Elsevier B.V. All rights reserved.

Degradation of polylactic acid (Pla) at different doses of gamma radiation; Degradacion del acido polilactico (PLA) a diferentes dosis de radiacion gamma

Energy Technology Data Exchange (ETDEWEB)

Castillo R, Y.

2015-07-01

The excessive use of polymers such as polyethylene (PET), polystyrene (Ps) and recently the polylactic acid (Pla) that take more than 20 years to degrade, have caused great pollution in the environment. In this study the effects of gamma radiation in the Pla to different doses were studied, in order to reduce the degradation time of this polymer. The changes in physico-chemical structure of Pla during radiation were studied by thermo-gravimetric/Mass analysis; differential scanning calorimetry; scanning electron microscopy; X-ray dispersive analysis; infrared spectroscopy; X-ray diffraction and mechanical tests of hardness, elasticity and deformation. With scanning electron microscopy, the morphology of the Pla surface unirradiated was observed, in which an apparently smooth surface was observed, after changes that had the Pla when irradiated also was observed, where the effects of radiation were observed in form of scratch, agglomeration and small fractures. By X-ray dispersive analysis was determined and verified the elemental chemical composition of the Pla; as expected the tests showed only carbon, oxygen and hydrogen. With thermo-gravimetric/Mass analysis the decomposition temperatures of Pla were determined, identifying that the degradation compounds are CO, CO{sub 2} and CH{sub 4}. With infrared spectrometry the major peaks of Pla were observed before and after being irradiated with increasing of radiation dose the intensity of the bands decreased. Also by X-ray diffraction was observed that the polymer is an amorphous material. The mechanical tests indicate that the values of each of the tests decrease significantly with increasing the radiation dose. (Author)

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.

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.

Simple, rapid, and sensitive liquid chromatography-fluorescence method for the quantification of tranexamic acid in blood

NARCIS (Netherlands)

Huertas-Pérez, José Fernando; Heger, Michal; Dekker, Henk; Krabbe, Hans; Lankelma, Jan; Ariese, Freek

2007-01-01

Tranexamic acid (TA) is a synthetic antifibrinolytic agent that is being considered as a candidate adjuvant drug for site-specific pharmaco-laser therapy of port wine stains. For drug utility studies, a high-performance liquid chromatography (HPLC)-fluorescence method was developed for the

[Effects of simulating acid rain on photosynthesis and chlorophyll fluorescence parameters of Quercus glauca Quercus glauca].

Science.gov (United States)

Wang, Sai; Yi, Li-Ta; Yu, Shu-Quan; Zhang, Chao; Shi, Jing-Jing

2014-08-01

At three levels of simulated acid rainfall intensities with pH values of 2.5 (severe), 40 (medium) and 5.6 (light) respectively, the responses of chlorophyll fluorescence and photosynthetic parameters of Quercus glauca seedlings were studied in three acid rainfall treatments, i. e. only the aboveground of seedlings exposed to acid rain (T1), both of the seedlings and soil exposed to acid rain (T2), only the soil exposed to acid rain (T3) compared with blank control (CK). Under the severe acid rainfall, T1 significantly inhibited chlorophyll synthesis, and thus reduced the primary photochemical efficiency of PS II ( F(v)/F(m)), potential activity of PS II (F(v)/F(o)) , apparent quantum (Y), net photosynthetic rate (P(n)), and transpiration rate (T(r)), but increased the light compensation point (LCP) and dark respiration rate (R(d)) of Q. glauca seedlings. T2 inhibited, but T3 played a little enhancement on the aforementioned parameters of Q. glauca seedlings. Under the conditions of medium and light acid rainfall intensities, the above parameters in the three treatments were higher than that of CK, except with lower R(d). The chlorophyll fluorescence and photosynthetic parameters showed a similar tendency in the three treatments, i. e. T2>T3 >T1. It indicated that T1 had the strongest inhibition on seedlings in condition of the severe acid rainfall, while T2 had the most dramatic facilitating effect on seedlings under the medium and light acid rainfall. Intensity of acid rainfall had significant influences on SPAD, F(v)/F(m), F(v)/F(o), Y, P(n), T(r), and maximum photosynthetic rate (A(max)), whereas treatments of acid rainfall affected SPAD, F(v)/F(m), Y, P(n), T(r), A(max) and light saturation point (LSP). The interaction of acid rainfall intensities and treatments played significant effects on SPAD, F(v)/F(m), Y, P(n) and A(max).

Spectral characterization of the fluorescent components present in humic substances, fulvic acid and humic acid mixed with pure benzo(a)pyrene solution

Science.gov (United States)

El Fallah, Rawa; Rouillon, Régis; Vouvé, Florence

2018-06-01

The fate of benzo(a)pyrene (BaP), a ubiquitous contaminant reported to be persistent in the environment, is largely controlled by its interactions with the soil organic matter. In the present study, the spectral characteristics of fluorophores present in the physical fractions of the soil organic matter were investigated in the presence of pure BaP solution. After extraction of humic substances (HSs), and their fractionation into fluvic acid (FA) and humic acid (HA), two fluorescent compounds (C1 and C2) were identified and characterized in each physical soil fraction, by means of fluorescence excitation-emission matrices (FEEMs) and Parallel Factor Analysis (PARAFAC). Then, to each type of fraction having similar DOC content, was added an increasing volume of pure BaP solution in attempt to assess the behavior of BaP with the fluorophores present in each one. The application of FEEMs-PARAFAC method validated a three-component model that consisted of the two resulted fluorophores from HSs, FA and HA (C1 and C2) and a BaP-like fluorophore (C3). Spectral modifications were noted for components C2HSs (C2 in humic substances fraction) (λex/λem: 420/490-520 nm), C2FA (C2 in fulvic acid fraction) (λex/λem: 400/487(517) nm) and C1HA (C1 in humic acid fraction) (λex/λem: 350/452(520) nm). We explored the impact of increasing the volume of the added pure BaP solution on the scores of the fluorophores present in the soil fractions. It was found that the scores of C2HSs, C2FA, and C1HA increased when the volume of the added pure BaP solution increased. Superposition of the excitation spectra of these fluorophores with the emission spectrum of BaP showed significant overlaps that might explain the observed interactions between BaP and the fluorescent compounds present in SOM physical fractions.

Intraoperative confocal microscopy in the visualization of 5-aminolevulinic acid fluorescence in low-grade gliomas.

Science.gov (United States)

Sanai, Nader; Snyder, Laura A; Honea, Norissa J; Coons, Stephen W; Eschbacher, Jennifer M; Smith, Kris A; Spetzler, Robert F

2011-10-01

Greater extent of resection (EOR) for patients with low-grade glioma (LGG) corresponds with improved clinical outcome, yet remains a central challenge to the neurosurgical oncologist. Although 5-aminolevulinic acid (5-ALA)-induced tumor fluorescence is a strategy that can improve EOR in gliomas, only glioblastomas routinely fluoresce following 5-ALA administration. Intraoperative confocal microscopy adapts conventional confocal technology to a handheld probe that provides real-time fluorescent imaging at up to 1000× magnification. The authors report a combined approach in which intraoperative confocal microscopy is used to visualize 5-ALA tumor fluorescence in LGGs during the course of microsurgical resection. Following 5-ALA administration, patients with newly diagnosed LGG underwent microsurgical resection. Intraoperative confocal microscopy was conducted at the following points: 1) initial encounter with the tumor; 2) the midpoint of tumor resection; and 3) the presumed brain-tumor interface. Histopathological analysis of these sites correlated tumor infiltration with intraoperative cellular tumor fluorescence. Ten consecutive patients with WHO Grades I and II gliomas underwent microsurgical resection with 5-ALA and intraoperative confocal microscopy. Macroscopic tumor fluorescence was not evident in any patient. However, in each case, intraoperative confocal microscopy identified tumor fluorescence at a cellular level, a finding that corresponded to tumor infiltration on matched histological analyses. Intraoperative confocal microscopy can visualize cellular 5-ALA-induced tumor fluorescence within LGGs and at the brain-tumor interface. To assess the clinical value of 5-ALA for high-grade gliomas in conjunction with neuronavigation, and for LGGs in combination with intraoperative confocal microscopy and neuronavigation, a Phase IIIa randomized placebo-controlled trial (BALANCE) is underway at the authors' institution.

[1,10]Phenanthroline based cyanine dyes as fluorescent probes for ribonucleic acids in live cells

Science.gov (United States)

Kovalska, Vladyslava; Kuperman, Marina; Varzatskii, Oleg; Kryvorotenko, Dmytro; Kinski, Elisa; Schikora, Margot; Janko, Christina; Alexiou, Christoph; Yarmoluk, Sergiy; Mokhir, Andriy

2017-12-01

A series of monomethine, trimethine- and styrylcyanine dyes based on a [1,10]phenanthroline moiety was synthesized, characterized and investigated as potential fluorescent probes for nucleic acids in cell free settings and in cells. The dyes were found to be weakly fluorescent in the unbound state, whereas upon the binding to dsDNA or RNA their emission intensity raised up to 50 times (for monomethine benzothiazole derivative FT1 complexed with RNA). The strongest fluorescence intensity in assemblies with dsDNA and RNA was observed for the trimethine benzothiazole derivative FT4. The quantum yield of FT4 fluorescence in its complex with dsDNA was found to be 1.5% and the binding constant (K b) was estimated to be 7.9 × 104 M-1 that is a typical value for intercalating molecules. The FT4 dye was found to be cell membrane permeable. It stains RNA rich components—the nucleoli and most probably the cytoplasmic RNA. FT4 bound to RNAs delivers a very strong fluorescence signal, which makes this easily accessible dye a potentially useful alternative to known RNA stains, e.g. expensive SYTO® 83. The advantage of FT4 is its easy synthetic access including no chromatographic purification steps, which will be reflected in its substantially lower price.

The Arabidopsis thaliana REDUCED EPIDERMAL FLUORESCENCE1 gene encodes an aldehyde dehydrogenase involved in ferulic acid and sinapic acid biosynthesis.

Science.gov (United States)

Nair, Ramesh B; Bastress, Kristen L; Ruegger, Max O; Denault, Jeff W; Chapple, Clint

2004-02-01

Recent research has significantly advanced our understanding of the phenylpropanoid pathway but has left in doubt the pathway by which sinapic acid is synthesized in plants. The reduced epidermal fluorescence1 (ref1) mutant of Arabidopsis thaliana accumulates only 10 to 30% of the sinapate esters found in wild-type plants. Positional cloning of the REF1 gene revealed that it encodes an aldehyde dehydrogenase, a member of a large class of NADP(+)-dependent enzymes that catalyze the oxidation of aldehydes to their corresponding carboxylic acids. Consistent with this finding, extracts of ref1 leaves exhibit low sinapaldehyde dehydrogenase activity. These data indicate that REF1 encodes a sinapaldehyde dehydrogenase required for sinapic acid and sinapate ester biosynthesis. When expressed in Escherichia coli, REF1 was found to exhibit both sinapaldehyde and coniferaldehyde dehydrogenase activity, and further phenotypic analysis of ref1 mutant plants showed that they contain less cell wall-esterified ferulic acid. These findings suggest that both ferulic acid and sinapic acid are derived, at least in part, through oxidation of coniferaldehyde and sinapaldehyde. This route is directly opposite to the traditional representation of phenylpropanoid metabolism in which hydroxycinnamic acids are instead precursors of their corresponding aldehydes.

Time-resolved spectral studies of blue-green fluorescence of artichoke (Cynara cardunculus L. Var. Scolymus) leaves: identification of chlorogenic acid as one of the major fluorophores and age-mediated changes.

Science.gov (United States)

Morales, Fermín; Cartelat, Aurélie; Alvarez-Fernández, Ana; Moya, Ismael; Cerovic, Zoran G

2005-12-14

Synchrotron radiation and the time-correlated single-photon counting technique were used to investigate the spectral and time-resolved characteristics of blue-green fluorescence (BGF) of artichoke leaves. Leaves emitted BGF under ultraviolet (UV) excitation; the abaxial side was much more fluorescent than the adaxial side, and in both cases, the youngest leaves were much more fluorescent than the oldest ones. The BGF of artichoke leaves was dominated by the presence of hydroxycinnamic acids. A decrease in the percentage of BGF attributable to the very short kinetic component (from 42 to 20%), in the shape of the BGF excitation spectra, and chlorogenic acid concentrations indicate that there is a loss of hydroxycinnamic acid with leaf age. Studies on excitation, emission, and synchronized fluorescence spectra of leaves and trichomes and chlorogenic acid contents indicate that chlorogenic acid is one of the main blue-green fluorophores in artichoke leaves. Results of the present study indicate that 20-42% (i.e., the very short kinetic component) of the overall BGF is emitted by chlorogenic acid. Time-resolved BGF measurements could be a means to extract information on chlorogenic acid fluorescence from the overall leaf BGF.

Carbon dots prepared from citric acid and urea as fluorescent probes for hypochlorite and peroxynitrite

International Nuclear Information System (INIS)

Simões, Eliana F. C.; Leitão, João M. M.; Esteves da Silva, Joaquim C. G.

2016-01-01

Carbon dots (CDs) were prepared from citric acid and urea, and their fluorescence was found to be quenched by hypochlorite and peroxynitrite. Microwave based synthesis gives CDs with excitation/emission wavelength-dependent quantum yields (8 % at 400/520 nm; 10 % at 360/451 nm; 12 % at 350/420 nm). Quenching of fluorescence depends on pH values, and response is most selective and sensitive to hypochlorite at pH 4, and to peroxynitrite at pH 9. The lower detection limits are 0.5 and 1.5 μM, respectively. The method was successfully applied to quantify hypochlorite and peroxynitrite in standard solutions and in spiked dilute serum samples. (author)

Pain-alleviating effect of bupivacaine polylactic acid microspheres in rabbits%布比卡因聚乳酸微球在家兔体内的缓释效应

Institute of Scientific and Technical Information of China (English)

傅强; 王新华; 邹最; 俞媛; 高申; 钟延强; 张宏

2006-01-01

BACKGROUND: Bupivacaine is widely used to alleviate post-operation pain and cure acute and chronic pain caused by inflammation or cancer.Its analgesic time cannot meet the request that drug is released slowly to prolong the analgesic time in clinic.OBJECTIVE: To detect the alleviating effect of bupivacaine polylactic acid microspheres taking high molecular polymer-polylactic acid as vector in rabbits with high performance liquid chromatograph (HPLC) and traditional skin test method.DESIGN: A completely randomized controlled animal experimental study.SETTING: School of Pharmacy, Second Military Medical University of Chinese PLAMATERIALS: Sixteen New Zealand rabbits, weighing (2.58±0.17)kg were used in this experiment.INTERVENTIONS: The experiment was carried out at the Department of pharmaceutics, School of Pharmacy, Second Military Medical University of Chinese PLA between September and November 2002. ① Animal models were established according to traditional skin test method. ② Totally 16 New Zealand rabbits were randomly divided into 2 groups: Group A and Group B, with 8 in each one. 5 mg/kg bupivacaine parenteral solution was injected subcutaneously in Group A, 5 mg/kg bupivacaine polylactic acid microspheres were implanted between subcutaneous tissue and sarcolemma in Group B. We took 1.5 mL blood from ear border vein at 5, 10, 20, 30,45 minutes, 1, 2, 3, 4, 6, 8, 12 and 24 hours after administration of bupivacaine parenteral solution respectively in Group A and another 1.5 mL at 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 3 6, 48 and 60 hours after admistration of bupivacaine microsphere powder for index detection. ③ HPLC method was used to detect the concentration and releasing effect of bupivacaine in blood serum.MAIN OUTCOME MEASURES: Concentration change of bupivacaine in blood serum and efficacy diameter of local anesthetic.RESULTS:All the 16 rabbits entered the stage of result analysis. ①Change of bupivacaine concentration: Plasma bupivacaine concentration

[Mechanical properties of polylactic acid/beta-tricalcium phosphate composite scaffold with double channels based on three-dimensional printing technique].

Science.gov (United States)

Lian, Qin; Zhuang, Pei; Li, Changhai; Jin, Zhongmin; Li, Dichen

2014-03-01

To improve the poor mechanical strength of porous ceramic scaffold, an integrated method based on three-dimensional (3-D) printing technique is developed to incorporate the controlled double-channel porous structure into the polylactic acid/beta-tricalcium phosphate (PLA/beta-TCP) reinforced composite scaffolds (double-channel composite scaffold) to improve their tissue regeneration capability and the mechanical properties. The designed double-channel structure inside the ceramic scaffold consisted of both primary and secondary micropipes, which parallel but un-connected. The set of primary channels was used for cell ingrowth, while the set of secondary channels was used for the PLA perfusion. Integration technology of 3-D printing technique and gel-casting was firstly used to fabricate the double-channel ceramic scaffolds. PLA/beta-TCP composite scaffolds were obtained by the polymer gravity perfusion process to pour PLA solution into the double-channel ceramic scaffolds through the secondary channel set. Microscope, porosity, and mechanical experiments for the standard samples were used to evaluate the composite properties. The ceramic scaffold with only the primary channel (single-channel scaffold) was also prepared as a control. Morphology observation results showed that there was no PLA inside the primary channels of the double-channel composite scaffolds but a dense interface layer between PLA and beta-TCP obviously formed on the inner wall of the secondary channels by the PLA penetration during the perfusion process. Finite element simulation found that the compressive strength of the double-channel composite scaffold was less than that of the single-channel scaffold; however, mechanical tests found that the maximum compressive strength of the double-channel composite scaffold [(21.25 +/- 1.15) MPa] was higher than that of the single-channel scaffold[ (9.76 +/- 0.64) MPa]. The double-channel composite scaffolds fabricated by 3-D printing technique have

Investigation on hemolytic effect of poly(lactic co-glycolic) acid nanoparticles synthesized using continuous flow and batch processes

Energy Technology Data Exchange (ETDEWEB)

Libi, Sumit; Calenic, Bogdan; Astete, Carlos E.; Kumar, Challa; Sabliov, Cristina M.

2017-01-01

With the increasing interest in polymeric nanoparticles for biomedical applications, there is a need for continuous flow methodologies that allow for the precise control of nanoparticle synthesis. Poly(lactide-co-glycolic) acid (PLGA) nanoparticles with diameters of 220–250 nm were synthesized using a lab-on-a-chip, exploiting the precise flow control offered by a millifluidic platform. The association and the effect of PLGA nanoparticles on red blood cells (RBCs) were compared for fluorescent PLGA nanoparticles made by this novel continuous flow process using a millifluidic chip and smaller PLGA nanoparticles made by a batch method. Results indicated that all PLGA nanoparticles studied, independent of the synthesis method and size, adhered to the surface of RBCs but had no significant hemolytic effect at concentrations lower than 10 mg/ml.

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.

Branched-chain Amino Acid Biosensing Using Fluorescent Modified Engineered Leucine/Isoleucine/Valine Binding Protein

Directory of Open Access Journals (Sweden)

Koji Sode

2007-06-01

Full Text Available A novel fluorescence sensing system for branched-chain amino acids (BCAAswas developed based on engineered leucine/isoleucine/valine-binding proteins (LIVBPsconjugated with environmentally sensitive fluorescence probes. LIVBP was cloned fromEscherichia coli and Gln149Cys, Gly227Cys, and Gln254Cys mutants were generated bygenetic engineering. The mutant LIVBPs were then modified with environmentallysensitive fluorophores. Based on the fluorescence intensity change observed upon thebinding of the ligands, the MIANS-conjugated Gln149Cys mutant (Gln149Cys-M showedthe highest and most sensitive response. The BCAAs Leu, Ile, and Val can each bemonitored at the sub-micromolar level using Gln149Cys-M. Measurements were alsocarried out on a mixture of BCAFAs and revealed that Gln149Cys-M-based measurementis not significantly affected by the change in the molar ratio of Leu, Ile and Val in thesample. Its high sensitivity and group-specific molecular recognition ability make the newsensing system ideally suited for the measurement of BCAAs and the determination of theFischer ratio, an indicator of hepatic disease involving metabolic dysfunction.

Investigation of adsorptive fractionation of humic acid on graphene oxide using fluorescence EEM-PARAFAC.

Science.gov (United States)

Lee, Bo-Mi; Seo, Young-Soo; Hur, Jin

2015-04-15

In this study, the adsorptive fractionation of a humic acid (HA, Elliott soil humic acid) on graphene oxide (GO) was examined at pH 4 and 6 using absorption spectroscopy and fluorescence excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC). The extent of the adsorption was greater at pH 4.0 than at pH 6.0. Aromatic molecules within the HA were preferentially adsorbed onto the GO surface, and the preferential adsorption was more pronounced at pH 6, which is above the zero point of charge of GO. A relative ratio of two PARAFAC humic-like components (ex/em maxima at 270/510 nm and at (250, 265)/440 nm) presented an increasing trend with larger sizes of ultrafiltered humic acid fractions, suggesting the potential for using fluorescence EEM-PARAFAC for tracking the changes in molecular sizes of aromatic HA molecules. The individual adsorption behaviors of the two humic-like components revealed that larger sized aromatic components within HA had a higher adsorption affinity and more nonlinear isotherms compared to smaller sized fractions. Our results demonstrated that adsorptive fractionation of HA occurred on the GO surface with respect to their aromaticity and the sizes, but the degree was highly dependent on solution pH as well as the amount of adsorbed HS (or available surface sites). The observed adsorption behaviors were reasonably explained by a combination of different mechanisms previously suggested. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sciatic nerve regeneration by transplantation of Schwann cells via erythropoietin controlled-releasing polylactic acid/multiwalled carbon nanotubes/gelatin nanofibrils neural guidance conduit.

Science.gov (United States)

Salehi, Majid; Naseri-Nosar, Mahdi; Ebrahimi-Barough, Somayeh; Nourani, Mohammdreza; Khojasteh, Arash; Hamidieh, Amir-Ali; Amani, Amir; Farzamfar, Saeed; Ai, Jafar

2018-05-01

The current study aimed to enhance the efficacy of peripheral nerve regeneration using an electrically conductive biodegradable porous neural guidance conduit for transplantation of allogeneic Schwann cells (SCs). The conduit was produced from polylactic acid (PLA), multiwalled carbon nanotubes (MWCNTs), and gelatin nanofibrils (GNFs) coated with the recombinant human erythropoietin-loaded chitosan nanoparticles (rhEpo-CNPs). The PLA/MWCNTs/GNFs/rhEpo-CNPs conduit had the porosity of 85.78 ± 0.70%, the contact angle of 77.65 ± 1.91° and the ultimate tensile strength and compressive modulus of 5.51 ± 0.13 MPa and 2.66 ± 0.34 MPa, respectively. The conduit showed the electrical conductivity of 0.32 S cm -1 and lost about 11% of its weight after 60 days in normal saline. The produced conduit was able to release the rhEpo for at least 2 weeks and exhibited favorable cytocompatibility towards SCs. For functional analysis, the conduit was seeded with 1.5 × 10 4 SCs and implanted into a 10 mm sciatic nerve defect of Wistar rat. After 14 weeks, the results of sciatic functional index, hot plate latency, compound muscle action potential amplitude, weight-loss percentage of wet gastrocnemius muscle and Histopathological examination using hematoxylin-eosin and Luxol fast blue staining demonstrated that the produced conduit had comparable nerve regeneration to the autograft, as the gold standard to bridge the nerve gaps. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1463-1476, 2018. © 2017 Wiley Periodicals, Inc.

Time-resolved fluorescence of cationic dyes covalently bound to poly(methacrylic acid) in rigid media

Energy Technology Data Exchange (ETDEWEB)

Paulo Moises de Oliveira, Hueder [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, SP (Brazil); Gehlen, Marcelo Henrique [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, SP (Brazil)]. E-mail: marcelog@iqsc.usp.br

2006-12-15

Atactic poly(methacrylic acid) labeled with acridine and Nile blue (NB) were studied by photophysical techniques in bulk solid state and in solution-cast films over different surfaces (glass, ITO, and polymethylmethacrylate). In the systems with both dyes, energy transfer from acridine to NB occurs with an efficiency depending on the type of substrate (solid or film). The films are more disordered fluorescent rigid media than the bulk chromophoric or bichromophoric polymers, and this effect is ascribed to inhomogeneous distribution of the dyes in the film. This effect enhances dye bimolecular interactions and increases the energy transfer rates between acridine donor and NB acceptor. Bimodal distributions of donor fluorescence lifetimes are observed.

A general sensing strategy for detection of Fe{sup 3+} by using amino acid-modified graphene quantum dots as fluorescent probe

Energy Technology Data Exchange (ETDEWEB)

Ma, Qi [College of Chemistry and Environmental Engineering, and Institute of Applied Chemistry, Shanxi Datong University, Datong, Shanxi, 037009 (China); Song, Jinping, E-mail: songjphxsxdt@163.com [College of Chemistry and Environmental Engineering, and Institute of Applied Chemistry, Shanxi Datong University, Datong, Shanxi, 037009 (China); Institute of Environmental Science, Shanxi University, Taiyuan, 030006 (China); Wang, Shangzhi; Yang, Jie; Guo, Yong [College of Chemistry and Environmental Engineering, and Institute of Applied Chemistry, Shanxi Datong University, Datong, Shanxi, 037009 (China); Dong, Chuan, E-mail: dc@sxu.edu.cn [Institute of Environmental Science, Shanxi University, Taiyuan, 030006 (China)

2016-12-15

Graphical abstract: Three kinds of amino acid-modified graphene quantum dots (GQDs) were synthesized through acylation and amination reactions. The as-synthesized GQDs can emit strong blue fluorescence. The presence of Fe{sup 3+} will cause obvious fluorescence quenching of the three kinds of GQDs. Based on these, a general sensing strategy for detection of Fe{sup 3+} was successfully developed. - Highlights: • Amino acid-modified graphene quantum dots (GQDs) were synthesized through acylation and amination reactions. • The presence of Fe{sup 3+} will cause obvious fluorescence quenching of the three kinds of GQDs. • A general sensing strategy for Fe{sup 3+} detection was successfully developed. • The proposed sensing strategy can successfully detect Fe{sup 3+} in real water sample. - Abstract: Amino acid-modified graphene quantum dots (GQDs) were synthesized through acylation and amination reactions. The as-synthesized GQDs were characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV–vis absorption and fluorescence spectroscopy. A general sensing strategy for detection of Fe{sup 3+} was successfully developed. The detection limit can reach as low as 50 nM. Moreover, the proposed sensing system was successfully employed to detect Fe{sup 3+} in real water sample, and satisfactory results were obtained. This work will open up new avenues to develop potential applications of GQDs materials in environmental monitoring.

LASER BIOLOGY AND MEDICINE: Application of laser fluorimetry for determining the influence of a single amino-acid substitution on the individual photophysical parameters of a fluorescent form of a fluorescent protein mRFP1

Science.gov (United States)

Banishev, A. A.; Vrzheshch, E. P.; Shirshin, E. A.

2009-03-01

Individual photophysical parameters of the chromophore of a fluorescent protein mRFP1 and its two mutants (amino-acid substitution at position 66 - mRFP1/ Q66C and mRFP1/Q66S proteins) are determined. For this purpose, apart from conventional methods of fluorimetry and spectrophotometry, nonlinear laser fluorimetry is used. It is shown that the individual extinction coefficients of the chromophore of proteins correlate (correlation coefficient above 0.9) with the volume of the substituted amino-acid residue at position 66 (similar to the positions of the absorption, fluorescence excitation and emission maxima).

A comparative study on the effectiveness of ozonated water and peracetic acid in the storability of packaged fresh-cut melon.

Science.gov (United States)

Botondi, Rinaldo; Moscetti, Roberto; Massantini, Riccardo

2016-05-01

Ozonated water and peracetic acid were tested as sanitizers to enhance the storability of fresh-cut melon cubes. Sanitizers were also combined with suitable packaging materials (polypropylene and polylactic acid based plastic films). Fresh-cut melon cubes were stored at 4 °C for up to 7 days. Ozonated water and peracetic acid treatments were given by dipping cubes into 0.8 ppm O3 and 100 ppm Tsunami 100™ solutions, respectively, for 3 min. Both sanitizers exhibited efficiency in reducing the total microbial counts on melon cubes (acid treatment in combination with polypropylene film packaging, consequently developing off-odors starting from day 3. Strong color changes were noted in cubes stored in polylactic acid packaging after 7 days of storage, affecting the sensory quality of the melon cubes. Sensory evaluation (overall visual quality) indicated loss in flavor in the polypropylene packaging. The overall visual quality started to decline on 3rd day because of the development of translucency.Overall, the use of ozone in combination with polypropylene packaging provided the best solution to maintain the quality of melon cubes for up to 5 days of storage at 4 °C.