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ABSTRACT: A biodegradable and thermoplastic elastomer—poly(L-lactide-co-ε-caprolactone) (PLLCA)—was reinforced with 5, 10, 20, and 30wt% of CaCO3 whiskers. We assessed the influence of the CaCO3 whisker content on the mechanical and thermal properties of the PLLCA/CaCO3 whisker composites. Scanning electron microscopy (SEM) revealed that the CaCO3 whiskers were uniformly distributed in the composite matrices. The results of differential scanning calorimetry (DSC) and
dynamic mechanical analysis (DMA) showed that the glass transition temperatures (T
g) of the composites increased slightly with increasing CaCO3 whisker content. At low CaCO3 whisker contents, the tensile strengths of the composites increased sharply with increasing CaCO3 content, the Young’s moduli also increased, and the elongation at break values gradually decreased. Thermogravimetric analysis
(TGA) showed that the CaCO3 whiskers can promote the thermal degradation of PLLCA. Shape memory test results indicated that an appropriate amount of
CaCO3 whiskers can improve the shape memory properties of PLLCA.
KeywordsParticle reinforcement–Mechanical properties–Thermal degradation–Shape memory properties
Journal of Polymer Research 04/2012; 18(3):329-336. · 1.73 Impact Factor
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Macromolecular Materials and Engineering 03/2010; 295(4):381 - 385. · 1.99 Impact Factor
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ABSTRACT: Composite scaffolds for applications in bone engineering from poly(D,L-lactide) (PDLLA) incorporated with different proportional bioactive wollastonite powders were prepared through a salt-leaching method, using NH4HCO3 as porogen. The pore structures and morphology of the scaffolds were determined by scanning electron microscopy (SEM). The bioactivity of composite materials was evaluated by examining its ability to initiate the formation of hydroxyapatite (Ca10(PO4)6(OH)2)(HAp) on its surface when immersed in simulated body fluids (SBF). The in vitro degradation behaviors of these scaffolds were systematically monitored at varying time periods of 1, 2, 4, 6, 8, 11, 14, 17, 20, 24, and 28 weeks postimmersion in SBF at 37°C. FT-IR, XPS, XRD, and SEM measurements revealed that hydroxyapatite commenced to form on the surface of the scaffolds after 7 days of immersion in SBF. The measurements of weight loss, pH, and molecular weight of the samples indicated that PDLLA/wollastonite composite scaffolds degraded slower than the pure PDLLA scaffolds do. Addition of wollastonite enhanced the mechanical property of the composite scaffolds. The in vitro osteoblast culture experiment confirmed the biocompatibility of the scaffold for the growth of osteo-blasts. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009.
Journal of Applied Polymer Science 08/2009; 114(6):3396 - 3406. · 1.29 Impact Factor
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ABSTRACT: The most commonly used anti-adhesion device for separation and isolation of wounded tissues after surgery is the polymeric membrane. In this study, a new anti-adhesion membrane from polylactide-polyethylene glycol tri-block copolymer (PELA) has been synthesized. The synthesized copolymers were characterized by gel permeation chromatography and (1)H nuclear magnetic resonance spectroscopy. PELA membrane was prepared by electrospun. The prepared copolymer membranes were more flexible than the control poly-d-l-lactic acid (PDLLA) membrane, as investigated by the measurements of glass transition temperature. Its biocompatibility and anti-adhesion capabilities were also evaluated. In vitro cell adhesions on the PELA copolymer membrane and PDLLA membrane were compared by the culture of mouse fibroblasts L929 on the surfaces. For in vivo evaluation of tissue anti-adhesion potential, the PDLLA and PELA copolymer membranes were implanted between cecum and peritoneal wall defects of rats and their tissue adhesion extents were compared. It was observed that the PELA copolymer membrane was very effective in preventing cell or tissue adhesion on the membrane surface, probably owing to the effects of hydrophilic polyethylene glycol.
Acta biomaterialia 05/2009; 5(7):2467-74. · 3.98 Impact Factor
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ABSTRACT: The aim of this study was to investigate the potential of poly(ethylene glycol-co-lactide) (PELA tri-block with a segmental sequence of PLA-PEG-PLA) electrospun membranes as drug-delivery vehicles using metronidazole as a model drug. PELA membranes with smooth surfaces and no bead defects were electrospun from polymer solutions containing 20% (w/v) PELA in 8:2 N,N-dimethyl formamide (DMF)/acetone. The morphology of the drug-loaded electrospun membranes was influenced by electrospinning parameters such as the flow rate and voltages during preparation. Metronidazole could be released from the electrospun membranes and was characterized by an initial burst effect. Higher voltages led to faster release rates, while an increase in the flow rate decreased the drug release. The incorporation of metronidazole into the electrospun membranes decreased their surface hydrophilicity. The amount of drug released from the electrospun membranes was effective in inhibiting microbial growth. Cell adhesion on the PELA membranes with or without drug was less than that on the homo-polymeric PDLLA membranes. Proliferation of L929 mouse fibroblasts on the PELA membranes was observed. This study confirms the potential of metronidazole-loaded PELA biodegradable electrospun membranes for optimizing the clinical therapy of post-surgical adhesions and infections.
Journal of Biomaterials Science Polymer Edition 02/2009; 20(9):1321-34. · 1.69 Impact Factor
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ABSTRACT: The aim of this study was to prepare and characterize a scaffold with an ionically crosslinked hydrogel coating layer containing a water-soluble drug, vancomycin, via a novel drug loading method for sustained drug delivery and surface modification. The poly(D,L-lactide acid) (PDLLA)/biphasic calcium phosphate (BCP) scaffold with a highly inter-connected porous structure was fabricated by a particle-leaching/thermally induced phase separation (TIPS) method. The pre-vacuumized scaffold was immersed into an alginate/vancomycin solution. Following impregnation by the solution, the scaffold was removed and immersed in a CaCl(2) solution for 30 min to allow gelation of the alginate solution. In this way, the drug was not exposed to organic solvents or detrimental temperature conditions and it could avoid loss of drug during the leaching process. The water contact angles of the scaffold surface decreased after being coated with the hydrogel. The in vitro drug release profile showed sustained release properties which were influenced by the alginate concentration and the dissolution medium. A standardized bacterial assay showed that the drug was still active after association with the scaffold by this gentle method of drug loading. The in vitro osteoblast culture experiments confirmed the biocompatibility of the scaffold for attachment and proliferation of osteoblasts.
International Journal of Pharmaceutics 05/2008; 353(1-2):74-87. · 3.35 Impact Factor
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ABSTRACT: To improve the hydrophilicity, pliability, and egradability of some biodegradable polymers such as polylactide (PLA), a triblock copolymer, and poly(ethylene glycol-co-lactide) (PELA) has been electrospun into fibrous membranes in the fiber sizes of 7.5 microm to 250 nm. The relationship between electrospinning parameters (such as voltage, concentration, and feeding rate) and the fiber diameters has been investigated. The characterizations for the structure and morphology of electrospun membranes were carried out using differential scanning calorimetry (DSC), (1)H NMR, and scanning electron microscopy (SEM). The hydrophilicity of the membrane was determined by contact angle measurements in bi-distilled water, and it was shown that the hydrophilicity of the copolymer could be adjusted by the content of the poly (ethylene glycol) (PEG) segment in the copolymer. The results of in vitro degradation study showed that the submicrostructure of the fibrous membrane and the incorporation of hydrophilic PEG into PLA block could accelerate the degradation of the membrane in regards to the changes of inherent viscosity, tensile strength, and weight loss.
Journal of Biomedical Materials Research Part A 10/2007; 82(3):680-8. · 2.63 Impact Factor
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ABSTRACT: To observe the biological behavior of canine bone marrow stromal cells (BMSCs) cultured in vitro with the astragalus polysaccharides-chitosan/polylactic acid (AP-C/PLA) and with the chitosan/polylactic acid (C/PLA) and to find a suitable compound material for periodontal tissue engineering.
BMSCs (induced 14 days by 50 mg/L vitamine C, 10(-8) mol/L dexamethasone, 10 mmol/L beta-sodium glycerylphosphate) were cultured on AP-C/PLA or C/PLA for 5 days respectively. The BMSCs attachment and the morphology were observed with scanning electronic microscope and the combining rates were counted. Type I collagen synthesis was examined with immunohistochemistry staining and the content of osteocalin was determined with radio-immunological method.
Combining rates, type I collagen synthesis, and the content of osteocalin of BMSCs on AP-C/PLA were significantly higher than those on C/PLA.
AP-C/PLA may promote the BMSC proliferation, differentiation and extracellular matrix synthesis, and it can be used as a good scaffold material for bone tissue engineering.
Zhong nan da xue xue bao. Yi xue ban = Journal of Central South University. Medical sciences 07/2005; 30(3):283-7.
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ABSTRACT: Carboxymethyl konjac glucomannan-chitosan (CKGM-CS) nanoparticles, which are well dispersed and stable in aqueous solution, were spontaneously prepared under very mild conditions via polyelectrolyte complexation. The physicochemical properties of the nanoparticles were identified by Zetasizer 3000 and Fourier transform infrared. It was found that at various CKGM and CS concentrations the particles ranged in size from approximately 50 to 1200 nm, and the zeta potential from 15 to 45 mV. By changing pH value of the medium and increasing the concentration of salt, the mean size of the particles increased and the zeta potential decreased. Also, investigations on the encapsulation efficiency of the bovine serum albumin loaded CKGM-CS nanoparticles were also undertaken. This nanoparticulate system driven by complex formation shows potential as an advanced drug delivery system for water-soluble drugs.
Biopolymers 06/2005; 78(1):1-8. · 2.87 Impact Factor
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ABSTRACT: Carboxymethyl konjac glucomannan-chitosan (CKGM-CS) nanoparticles were spontaneously prepared under very mild conditions via polyelectrolyte complexation. Bovine serum albumin (BSA), as a model protein drug, was incorporated into the CKGM-CS nanoparticles. The physicochemical properties of the BSA-loaded nanoparticles were identified by Zetasizer 3000 and FTIR spectrophotometry. Their sizes were from 330 nm to 900 nm; zeta potentials were positive according to varies CKGM/CS ratios. The encapsulation efficiency was up 20%. The release behavior in vitro of BSA from the nanoparticles was also investigated. We could find that the BSA release from the CKGM-CS nanoparticles is much more influenced by the CS coating layer than by the CKGM inner structure. And the CKGM-CS matrices not only exhibited pH-responsive properties, but ionic strength-sensitive properties. These systems may present a potential for pulsatile protein drug delivery.
Journal of Biomedical Materials Research Part B Applied Biomaterials 03/2005; 72(2):299-304. · 2.15 Impact Factor
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ABSTRACT: To make sure whether super-high molecular weight polylactate is toxic to the body after it has been implanted into the body for a long period.
We implanted super-high molecular weight polylactate into the rats and took the specimens of blood at 3, 6, 9, 12 months after the operation. The changes of proteins, electrolyte, enzyme and other indices were observed. At the same time, the tissue around the implants were taken out to carry out the histological observation.
At 3, 6, 9, 12 months after the operation, the levels of albumin, globulin, total bilirubin, direct bilirubin, triglyceride, glucose, K+, Na+, Cl-, Ca2+, alkaline phosphatase, glutamic-pyruvic transaminase in the blood plasma were all in the normal range; there were no significant differences between the experimental group and the control group. The level of lactate dehydrogenase increased slightly, but there was no statistically significant difference between the experimental group and the control group. There were no non-reversible immune rejection around the implants in the histological observation.
Super-high molecular weight polylactate is not toxic to the body after it has been implanted into the animals for a long period.
Sichuan da xue xue bao. Yi xue ban = Journal of Sichuan University. Medical science edition 12/2004; 35(6):764-6.
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ABSTRACT: To investigate the feasibility and clinical results of applying poly-DL-lactic acid (PDLLA) biomembranes in cleft palate repair.
68 cleft palate patients were divided into study group and control group. The traditional surgical method was used to control group to close the soft cleft palate, and the PDLLA biomembrane was used to study group and implanted into the surgical gap between the periosteum and bone at the hard palate, and fixed with suture. The duration, blood loss at operation, post-operative complication, wound healing and recovery were recorded and compared to conventional cleft palate repair.
Operations were successfully completed on all 34 patients. Wound healing of soft palate and uvula was uneventful with no incidence of fistula or dehiscence. The primary healing on tissue defect of hard palate occurred in 29 patients, secondary healing occurred in 3 patients, permanent fistula between the oral cavity and the nasal cavity occurred in only one patients, and 3 patients left over fistula on alveolar process. Compared to traditional cleft palate repair, blood loss and incidence of fistula on alveolar process were decreased; the average surgical time was 89.25 minutes and was not prolonged; and there was no significant increase in post-operative complication.
Hard cleft palate repair with PDLLA biomembranes is safe, simple and practical with good clinical results and is beneficial to minimize the bad influences towards the development and growth for maxilla of cleft palate patients.
Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 05/2004; 22(2):132-4.
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Macromolecular Rapid Communications 04/2004; 25(9):954 - 958. · 4.60 Impact Factor
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ABSTRACT: To investigate the influence of the viability and new bone formation of osteoblasts by the super high molecular weight poly D,L-lactic acid (SHMW-PDLLA).
1. The osteoblasts derived from neonatal rat were grown and maintained at steep of SHMW-PDLLA and normal culture medium. The viability and function of the osteoblasts were measured with MTT array. 2. The plate and screws made of SHMW-PDLLA were implanted and fixed at the artificial fractured mandible of dogs. Specimens were gained at 3 and 6 months and examined with macroscopy and SEM.
1. There is no significant difference of OD values between the experimental group and the control group (P > 0.05). The SHMW-PDLLA isn't toxic to osteoblast at 1 week and 2 weeks, and the toxicity is 3% at 3 days. 2. There were a lot of new bone formed between the implanted SHMW-PDLLA plate and bone tissues under SEM.
SHMW-PDLLA hasn't pathological influence on the viability and new bone formation of osteoblasts and it is feasible in tissue engineering of bone.
Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology 02/2003; 38(1):67-9.
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ABSTRACT: A well developed porous poly-D-L-lactide (PDLLA)/biphasic calcium phosphate (BCP) scaffold was coated with a hydrophilic poly (ethylene glycol) (PEG)/vancomycin composite for drug delivery and surface modification. The PDLLA/BCP scaffold, obtained by a salt-leaching method, possessed highly inter-connected pores (250–350 μm) and a high porosity (83.8%). The hydrophilic PEG was used to effectively entrap the drug inside the scaffold and to enhance the wettability of the hydrophobic surface of the PDLLA/BCP matrix. The scaffold with PEG/vancomycin coatings was fabricated by injecting the PEG/vancomycin composite solution into the pre-vacuumized scaffold. A standardized bacterial assay showed that the drug was still active after association with the bone scaffold. The in-vitro drug release study of vancomycin showed an initial burst release followed by a slower sustained release. The drug release behavior in vitro was investigated in detail by controlling the composite solution parameters: PEG molecular weight and PEG concentration. The release profiles showed that an increase in the PEG molecular weight and concentration resulted in a slower drug release rate. The water contact angles of the scaffold surface decreased after being coated with PEG. The in-vitro osteoblast culture experiment confirmed the biocompatibility of the scaffold for the growth of osteoblasts.
Materials Science and Engineering: C. 28(1):141-149.
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ABSTRACT: Considering the mechanical properties and shape-memory properties, we developed a novel biodegradable compound shape-memory-polymer blend composed of poly (l-lactide-co-ε-caprolactone) (PLLCA) and poly (l-lactide-co-glycolide) (PLLGA). In comparison with most reported shape-memory blends, our blend showed outstanding shape-memory properties at higher stationary-phase concentrations (more than 50% w/w). The results of scanning electron microscopy (SEM) demonstrated the immiscibility between PLLCA and PLLGA. The tensile test results revealed that blends with different PLLGA concentrations showed different mechanical properties. The results of the shape-memory tests suggested that the blends showed improved recovery and fixing performances with an increase in the PLLGA content, especially at PLLGA concentrations greater than 50 wt.%.
Materials Letters.
