Study of Synthesis of Copoly (lactic acid/glycolic acid) by Direct Melt Polycondensation

A two steps direct copolymerisation process was developed. The first step is to produce oligomer and then the oligomer of lactic acid/glycolic acid (90/10) is polymerized with binary catalyst tin chloride dihydrate/p-toluenesulfonic acid. In this way, the direct synthesis of copoly (lactic acid/glycolic acid) without any organic solvent was investigated. The properties and structures of products were characterized by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), X-ray diffraction and so on. The results show that comparatively high molecular weight copolymer of lactic acid and glycolic acid can be prepared by direct processing under appropriate technological conditions.

Degradation mechanisms of poly (lactic-co-glycolic acid) films in vitro under static and dynamic environment

To understand their degradation mechanisms, PLGA (50:50) polymer films were prepared and eroded in the static and dynamic medium system. The degradation behavior was characterized through weight-average molecular weight change, mass loss, water uptake, etc. The results show that in dynamic system, significant mass loss begins until 10 d while mass loss does not begin until 30 d later, while weight-average molecular weight decreases observably at the beginning, and the appeasable mass loss happens in 20 d in static system, which suggests that the dynamic degradation rate is slower even than degradation in static medium. A mechanism was proposed that specimens in static medium take up water homogeneously and cause the polymer chains to degrade all over the specimen cross sections, which creates free carboxylic acid groups which lead to a decrease of pH value inside the swollen polymer and accelerate degradation of the polymer. While pH value inside polymer keeps constant in dynamic medium because of flowing of simulated medium, which make the hydrolytic cleavage of ester bonds inside specimen delayed.

Viscoelasticity of repaired sciatic nerve by poly(lactic-co-glycolic acid) tubes

Medical-grade synthetic poly（lactic-co-glycolic acid） polymer can be used as a biomaterial for nerve repair because of its good biocompatibility, biodegradability and adjustable degradation rate. The stress relaxation and creep properties of peripheral nerve can be greatly improved by repair with poly（lactic-co-glycolic acid） tubes. ＂Fen sciatic nerve specimens were harvested from fresh corpses within 24 hours of death, and were prepared into sciatic nerve injury models by creating a 10 mm defect in each specimen. Defects were repaired by anastomosis with nerve autografts and poly（lactic-co-glycolic acid） tubes. Stress relaxation and creep testing showed that at 7 200 seconds the sciatic nerve anastomosed by poly（lactic-co-glycolic acid） tubes exhibited a greater decrease in stress and increase in strain than those anastomosed by nerve autografts. These findings suggest that poly（lactic-co-glycolic acid） exhibits good viscoelasticity to meet the biomechanical require- ments for a biomaterial used to repair sciatic nerve injury.

A novel artificial nerve graft for repairing longdistance sciatic nerve defects:a self-assembling peptide nanofiber scaffold-containing poly (lactic-co-glycolic acid) conduit

In this study, we developed a novel artificial nerve graft termed self-assembling peptide nanofiber scaffold （SAPNS）-containing poly（lactic-co-glycolic acid） （PLGA） conduit （SPC） and used it to bridge a 10-mm-long sciatic nerve defect in the rat. Retrograde tracing, behavioral testing and histomorphometric analyses showed that compared with the empty PLGA conduit implantation group, the SPC implantation group had a larger number of growing and extending axons, a markedly increased diameter of regenerated axons and a greater thickness of the myelin sheath in the conduit. Furthermore, there was an increase in the size of the neuromuscular junction and myofiber diameter in the target muscle. These findings suggest that the novel artificial SPC nerve graft can promote axonal regeneration and remyelination in the transected peripheral nerve and can be used for repairing peripheral nerve injury.

Dorsal root ganglion-derived Schwann cells combined with poly(lactic-co-glycolic acid)/chitosan conduits for the repair of sciatic nerve defects in rats

Schwann cells, nerve regeneration promoters in peripheral nerve tissue engineering, can be used to repair both the peripheral and central nervous systems. However, isolation and puriifcation of Schwann cells are complicated by contamination with ifbroblasts. Current reported measures are mainly limited by either high cost or complicated procedures with low cell yields or purity. In this study, we collected dorsal root ganglia from neonatal rats from which we obtained highly puriifed Schwann cells using serum-free melanocyte culture medium. The purity of Schwann cells （〉95%） using our method was higher than that using standard medium containing fetal bovine serum. The obtained Schwann cells were implanted into poly（lactic-co-glycolic acid）/chi-tosan conduits to repair 10-mm sciatic nerve defects in rats. Results showed that axonal diameter and area were signiifcantly increased and motor functions were obviously improved in the rat sciatic nerve tissue. Experimental ifndings suggest that serum-free melanocyte culture medium is conducive to purify Schwann cells and poly（lactic-co-glycolic acid）/chitosan nerve conduits combined with Schwann cells contribute to restore sciatic nerve defects.

Electrospun and woven silk fibroin/poly(lactic-coglycolic acid) nerve guidance conduits for repairing peripheral nerve injury

We have designed a novel nerve guidance conduit（NGC） made from silk fibroin and poly（lactic-co-glycolic acid） through electrospinning and weaving（ESP-NGCs）. Several physical and biological properties of the ESP-NGCs were assessed in order to evaluate their biocompatibility. The physical properties, including thickness, tensile stiffness, infrared spectroscopy, porosity, and water absorption were determined in vitro. To assess the biological properties, Schwann cells were cultured in ESP-NGC extracts and were assessed by morphological observation, the MTT assay, and immunohistochemistry. In addition, ESP-NGCs were subcutaneously implanted in the backs of rabbits to evaluate their biocompatibility in vivo. The results showed that ESP-NGCs have high porosity, strong hydrophilicity, and strong tensile stiffness. Schwann cells cultured in the ESP-NGC extract fluids showed no significant differences compared to control cells in their morphology or viability. Histological evaluation of the ESP-NGCs implanted in vivo indicated a mild inflammatory reaction and high biocompatibility. Together, these data suggest that these novel ESP-NGCs are biocompatible, and may thus provide a reliable scaffold for peripheral nerve repair in clinical application.

Controlled release of cisplatin and cancer cell apoptosis with cisplatin encapsulated poly(lactic-co-glycolic acid) nanoparticles

The goal of the present study is to utilize cis-diamminedichloroplatinum (cisplatin) loaded polymer nanoparticles (NPs) to give a controlled, extended, and local drug therapy for the treatment of cancer. We have used biodegradable and biocompatible poly(lactic-co-glycolic acid) (PLGA) to prepare the NPs by adjusting the double emulsion technique using poly(vinylalcohol) as a surface active agent. The PLGA NPs were characterized for particle size and shape, controlled release of cisplatin, and degradation. Cisplatin solubility in deionized water was increased up to 4 mg/mL by simply changing the solution parameters. Cisplatin encapsulated NPs were incubated in phosphate buffered saline (PBS) at 37?C to study the release kinetics of cisplatin. Cisplatin was released in a sustained manner with less than 20% release during a 3-day period followed by 50% release during a 21-day period. A degradation study of PLGA NPs demonstrated the loss of spherical shape during a 21-day period. We also examined the cisplatin sensitive A2780 cell apoptosis when cells were incubated with cisplatin encapsulated PLGA NPs. A large number of cell apoptosis occurred as a result of cisplatin release from the PLGA NPs. These results suggest that cisplatin encapsulated PLGA NPs can be used to treat the cancer cells by injecting them into a localized site minimizing the side effects.

Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve A mechanical analysis

Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly（lactic-co-glycolic acid） conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly（lactic-co-glycolic acid） conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly（lactic-co-glycolic acid） conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly（lactic-co-glycolic acid） conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly（lactic-co-glycolic acid） conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly（lactic-co-glycolic acid） conduits exhibited good intensity, elasticity and plasticity, indicating that poly（lactic-co-glycolic acid） conduits are suitable for sciatic nerve injury repair.

Evaluation of in vitro and in vivo immunostimulatory activities of poly(lactic-co-glycolic acid) nanoparticles loaded with soluble and autoclaved Leishmania infantum antigens: A novel vaccine candidate against visceral leishmaniasis

Objective: To prepare and characterize poly lactic-co-glycolic acid(PLGA) nanoparticles loaded with soluble leishmanial antigen or autoclaved leishmanial antigen and explore in vitro and in vivo immunogenicity of antigen encapsulated nanoparticles. Methods: Water/oil/water double emulsion technique was employed to synthesize PLGA nanoparticles, and scanning electron microscopy, Fourier transform infrared spectroscopy and Zeta-potential measurements were used to identify the characteristics of nanoparticles. Cytotoxicity of synthetized nanoparticles on J774 macrophage were investigated by MTT assays. To determine the in vitro immunostimulatory efficacies of nanoparticles, griess reaction and ELISA was used to measure the amounts of NO and cytokines. During the in vivo analysis, Balb/c mice were immunized with vaccine formulations, and protective properties of nanoparticles were measured by Leishman Donovan unit in the liver following the infection. Cytokine levels in spleens of mice were determined by ELISA. Results: MTT assay showed that neither soluble leishmanial antigen nor autoclaved leishmanial antigen encapsulated nanoparticles showed cytotoxicity against J774 macrophage cells. Contrary to free antigens, both autoclaved leishmanial antigen-nanoparticle and soluble leishmanial antigen-nanoparticle formulations led to a 10 and 16-fold increase in NO amounts by macrophages, respectively. Leishman Donovan unit calculations revealed that soluble leishmanial antigen-nanoparticles and autoclaved leishmanial antigen-nanoparticles yielded 52% and 64% protection against visceral leishmaniasis in mouse models. Besides, in vitro and in vivo tests demonstrated that by increasing IFN-γ and IL-12 levels and inhibiting IL-4 and IL-10 secretions, autoclaved leishmanial antigen-nanoparticles and soluble leishmanial antigennanoparticles triggered Th1 immune response. Conclusions: Both autoclaved leishmanial antigen-nanoparticles and soluble leishmanial antigen-nanoparticles formulations provide exceptional in vitro and in vivo immunostimulatory activities. Hence, PLGA-based antigen delivery systems are recommended as potential vaccine candidates against visceral leishmaniasis.

Preparation,Characterization,and Antitumor Efficacy of Camptothecine-Loaded Hydroxyapatite / Poly( lactic-co-glycolic acid ) Composite Nanofibers via Electrospinning

In the past decade, various medicated nanofibrous scaffolds have been developed as effective drug delivery systems for postsurgical cancer treatment.In this study, hydroxyapatite nanoparticles( HANPs) were used as carriers to load an anticancer agent—camptothecine( CPT),and the CPT-loaded HANPs( CPT@ HANPs) was then incorporated into poly( lactic-co-glycolic acid)( PLGA) nanofibers via electrospinning.Thus fabricated medicated nanofibrous mats( PLGA / CPT @ HANPs) were characterized by field emission scanning electron microscope( FESEM),transmission electron microscope( TEM), attenuated total reflection Fourier transform infrared spectroscopy( ATR-FTIR) and X-ray diffraction( XRD).The release profiles of CPT from the medicated electrospun mats were obtained and their in vitro anticancer efficacy against HeL a cells was also evaluated.The results showed that the CPT was successfully loaded onto the surface of HANPs,and the prepared electrospun mats exhibited a homogeneous and continuous morphology.Furthermore,the loaded CPT exhibited a sustained release behavior from the nanofibrous mats and the released CPT showed a long-term anticancer efficacy against HeL a cells.Therefore,the prepared medicated electrospun mats may be served as an effective drug delivery device for local antitumor treatment.

Effects of poly lactic-co-glycolic acid-Nogo A antibody delayed-release microspheres on regeneration of injured spinal cord in rats

BACKGROUND： Nogo A antigen is the major inhibiting factor blocking regeneration of the injured spinal cord. Neutralizing Nogo A antigens using Nogo A antibodies may help promote neurite regeneration and nervous function recovery. For successful regeneration, sustained release of the antibody from a biodegradable material loaded with Nogo A antibodies to the injury site is required. OBJECTIVE： To compare the therapeutic effects of poly lactic-co-glycolic acid （PLGA）-Nogo A antibody delayed-release microspheres and Nogo A antibody alone on spinal regeneration in Sprague-Dawley rats with complete transverse injury to the spinal cord. DESIGN, TIME AND SETTING： A randomized, controlled animal trial was performed at the Pharmacological Laboratory of West China Center of Medical Sciences, Sichuan University, between October 2007 and January 2008. MATERIALS： Goat anti-rat Nogo A monoclonal antibody was purchased from Santa, American; goat anti-rat neurofilament 200 monoclonal antibody was from Zhongshan Goldenbridge, Beijing, China; PLGA-Nogo A antibody delayed-release microspheres were provided by the College of Pharmacy, Sichuan University. METHODS： A total of 36 adult female Sprague Dawley rats were used to establish models of completely transected spinal cord injury, at T10. Animals were randomly divided into three groups （n=12）： model, Nogo A antibody alone, and Nogo A antibody delayed-release microsphere groups. After transverse injury of the spinal cord, 50 μ L normal saline solution, 50 μL normal saline solution containing 50μL g Nogo A antibody, and 50 μL normal saline solution containing 50 μg Nogo A antibody microspheres were administered to the respective groups at the injury site. MAIN OUTCOME MEASURES： The expression of Nogo A and neurofilament 200 in injured spinal cord was tested immunohistochemically, and motor function of rats was assessed by Basso-Beattie-Bresnahan （BBB） locomotor rating scale. RESULTS： Four weeks after injury, expression of Nogo A in microsphere group was significantly less than model and Nogo A antibody alone groups （P 〈 0.05）; while there was no significant difference between model and Nogo A antibody alone groups （P 〉 0.05）. Ten weeks after injury, microsphere group showed a significantly greater expression of neurofilament 200 than model and Nogo A antibody alone groups （P 〈 0.05）; while no significant difference was found between model and Nogo A antibody alone groups （P 〉 0.05）. At postoperative weeks 5 and 6, the score of BBB locomotor rating scale in microsphere group was significantly greater than the model group （P 〈 0.05）, and at postoperative weeks 7 10, the score was much greater than model and Nogo A antibody alone groups （P 〈 0.05）. CONCLUSION： Nogo A antibody delayed-release microspheres decreased Nogo A expression, increased neurofilament 200 expression in the injured spinal cord of rats, and promoted recovery of motor function through sustained drug release over a long-term period.

A porous poly(lactic-co-glycolic acid) scaffold induces innervation in a rabbit model of disc degeneration following annular injury

BACKGROUND： A degradable poly（lactic-co-glycolic acid） （PLGA） scaffold has been used to construct a degradable porous scaffold. This template can simulate the in vivo microenvironment and promote tissue formation. OBJECTIVE： To observe the histopathological changes during degeneration and regeneration of the intervertebral disc, and to analyze the effects of a PLGA scaffold on nerve fiber ingrowth into the lesion in vivo. DESIGN, TIME AND SETTING： A randomized, controlled animal experiment was performed at the Orthopaedic Laboratory, Clinic Medical Research Institution, Sir Run Run Shaw Hospital, Zhejiang University, from December 2007 to July 2008. MATERIALS： PLGA （China Textile Academy）; growth-associated protein-43 （Life-span, USA）; and protein gene product 9.5 antibody （AbD, United Kingdom） were used in this study. METHODS： Three consecutive segments of the intervertebral disc of thirty-two healthy adult male New Zealand rabbits were exposed, comprising L3-4, L4-5 and L5-6. Experimental intervertebral disc （L4-5 and L5-6） models were established by two different methods. In the test （trephine ＋ scaffold） group, a 5-mm deep hole was drilled into the annulus fibrosus using a 3-mm diameter trephine, and the PLGA scaffold was implanted into the hole. In the acupuncture group, the remaining experimental intervertebral disc annulus fibrosus was damaged using a 16G needle at a depth of 5 mm. The L3-4 disc served as a control. MAIN OUTCOME MEASURES： Intervertebral disc degeneration was assessed using radiography, magnetic resonance imaging, and histological examination at various time points post-surgery. Nerve fiber ingrowth into the degenerated intervertebral disc was observed using immunohistochemical staining for growth-associated protein-43 and protein gene product 9.5. RESULTS： Compared with the normal controls, the heights of the damaged intervertebral discs were decreased, and T2 signal intensity was decreased in the test and acupuncture groups 2 weeks post-surgery. Intervertebral disc degeneration was faster in the test group than in the acupuncture group. PLGA was coated with newly formed tissue, gradually degraded, and absorbed, and could induce tissue ingrowth deep into the annulus fibrosus. Results of immunohistochemical staining showed that nerve fibers were distributed in newly formed tissue in the test group, and in the superficial layer or surrounding scar tissue in the acupuncture group. CONCLUSION： A porous PLGA scaffold provides an important biological channel to induce nerve fiber ingrowth deep into the degenerated intervertebral disc.

A Study of Surface Modification of Poly(lactic-co-glycolic) Acid Using Argon Ion Irradiation

The effect of Argon ion irradiation to the surface properties of poly(lactic-co-glycolic) acid (PLGA) was studied. A beam of 170 keV Argon ions was implanted at different fluencies (1 × 1012, 1 × 1013, 1 × 1014, and 1 × 1015 ions/cm2). X-ray photoelectron spectroscopy (XPS) was used to analyze the evolution of the bonding microstructure of PLGA due to irradiation. Surface morphology was monitored using atomic force microscopy (AFM). AFM analysis shows that film roughness increased to maximum at the dose of 1 × 1014 ions/cm2 where the formations of hillocks were also detected. Hydrophilicity of PLGA is important for their applications in biomedicine such as bioscaffolds. Hydrophilicity was monitored using water contact angle measurements for both unmodified and ion-modified PLGA. It was observed that hydrophilicity of PLGA changes with the ion irradiation. This demonstrates that ion irradiation can be an alternative approach to control hydrophilicity of PLGA. PLGA scaffolds modified with ion irradiation could therefore be more suitable for the biomedical applications.

One-Step Preparation of Poly-Lactic-Co-Glycolic-Acid Microparticles to Prevent the Initial Burst Release of Encapsulated Water-Soluble Proteins

An initial burst is often observed during the release of active pharmaceutical ingredients (APIs) from poly-lactic-coglycolic-acid (PLGA) microparticles (MPs) which have been prepared by the emulsion-solvent evaporation method. Herein, we describe the development of a simple one-step coating method that suppresses the initial burst release process. This new method involves coating the PLGA-MPs with PLGA, with the coating process being performed through the phase separation of PLGA on the surface of PLGA-MPs using the emulsion-solvent evaporation method. Bovine serum albumin (BSA) was encapsulated in the PLGA-MPs as a model API. The coated MPs were spherical in shape with no pores on their smooth surface, whereas the non-coated PLGA-MPs had porous surfaces. An in vitro release study showed that the residual levels of BSA in the coated and non-coated PLGA-MPs after 1 h were about 99% and 16% of the original loads, respectively. The one-step coating method therefore represents a useful method for preparing PLGA-MPs that do not give an initial burst release of proteinaceous APIs.

Synthesis and Hydrophilic Performance of Poly(Lactic Acid)-Poly(Ethylene Glycol) Block Copolymers

Lactide was synthesized using lactic acid and stannous octoate as raw material and catalyst, respectively. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was prepared by lactide and poly (ethylene glycol) (PEG) via ring-opening polymerization. The most appropriate technological conditions of synthesis of lactide were researched in the paper. The copolymers were measured by Infrared spectroscopy (IR) and 1H nuclear magnetic resonance (1H NMR). The results proved that the lactide and PLA-PEG were synthesized successfully. Hydrophilic performance of the copolymer was measured by a water contact angle tester after prepared into a flat membrane. The water contact angle changed from 81.5? to 71.6?, which proved that the hydrophily of PLA-PEG was better than PLA.

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

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

Synthesis and Characterization of a Novel Functional Biodegradable Copolymer-Poly(lactic acid-4-hydroxyproline-polyethylene glycol)

A series of poly（lactic acid-4-hydroxyproline-polyethylene glycol） （PLA-Hpr-PEG） copolymers were synthesized by direct melt copolymerization of D,L-lactic acid and 4-hydroxyproline with different feed amount of polyethylene glycol （PEG） 0.1%, 0.5%, 1% and 5%, respectively. The properties of these copolymers were characterized by using IR spectroscopy, proton nuclear magnetic resonance （1H-NMR） spectroscopy, gel permeation chromatography （GPC）, X-ray diffraction and differential scaning calorimetry （DSC）. PLA-Hpr-PEG are amorphous copolymers. Copolymers showed increasing water uptake capacity with increasing PEG percentage in the feed, which result in an increasing degradable rate in phosphate buffer solution （pH 7.4） at 37℃.

Study of Thermal,Phase Morphological and Mechanical Properties of Poly(L-lactide)-b-Poly(ethylene glycol)-b-Poly(L-lactide)/Poly(ethylene glycol)Blend Bioplastics

A poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide)(PLLA-PEG-PLLA)block copolymer has great potential for use as a flexible bioplastic.Highly flexible bioplastics are required for flexible packaging applications.In this work,a PEG was incorporated into block copolymer as a plasticizer by solvent casting.PLLA-PEG-PLLA/PEG blends with different blend ratios were prepared,and the plasticizing effect and miscibility of PEG in block copolymer were intensively investigated compared to PLLA/PEG blends.The results indicated that the PEG was an effective plasticizer for the block copolymer.The blending of PEG decreased glass-transition temperature and accelerated the crystallization of both the PLLA and PLLA-PEG-PLLA matrices.The PEG was completely miscible when blended with block copolymer and it improved thermal stability of the block copolymer matrix but not of the PLLA matrix.Film extensibility of PLLA-PEG-PLLA/PEG blends steadily increased as the PEG ratio increased.These non-toxic and highly flexible PLLA-PEG-PLLA/PEG bioplastics are promising candidates for several applications such as biomedical devices,tissue scaffolds and packaging materials.

聚乳酸/聚乙二醇相变材料的结构与降温效果

针对加热卷烟中聚乳酸(PLA)材料降温效果不理想的问题,采用高相变焓的聚乙二醇(PEG)对PLA进行共混改性。通过熔融挤出制备了不同PEG分子量与含量的PLA/PEG相变材料,系统地研究了材料的相变行为、力学性能、亲水性能、降温效果以及相变前后的结构变化。结果表明,与纯PLA材料相比,PEG的引入使材料在40~70℃处的相变潜热增大,相变温度范围变宽。PLA/PEG材料的力学性能和亲水性受PEG质量分数的影响显著,但受PEG分子量影响不明显。随着PEG质量分数的增加,PLA/PEG材料的屈服强度和杨氏模量显著降低,断裂伸长率升高,亲水性提高。采用熔融沉积成型技术将PLA/PEG材料3D打印成降温滤嘴,并应用到加热卷烟中具有良好的降温效果,这归因于PEG的熔融吸热和PLA在玻璃化转变区域的热焓松弛。

静电纺丝MNZ/PLGA纳米纤维膜制备表征及药物释放研究

目的牙周炎是一种影响牙周组织的慢性感染性疾病,主要由牙菌斑中的细菌引起的,通过有效持续释放药物,达到杀灭细菌,有效地治疗牙周炎的目的。方法本研究采用静电纺丝技术,在高电场下,将有机高分子拉伸成纳米纤维,在收集滚筒上形成纳米纤维膜。将不同含量的甲硝唑(metronidazole,MNZ)(1wt%、3wt%、5wt%)负载到聚乳酸-羟基乙酸共聚物[poly(lactic-co-glycolicacid),PLGA]纳米纤维膜上。通过扫描电镜,傅里叶红外光谱、热重分析、亲疏水性测试、拉伸试验、生物相容性和药物释放进行表征,得到较为适合的MNZ/PLGA纳米纤维膜。结果随着甲硝唑含量的增加,PLGA复合纳米纤维丝直径逐渐增大,3wt%MNZ/PLGA复合膜均匀,当甲硝唑含量达到5wt%时,纤维丝粘连严重,且有大的颗粒状滴液团聚。MNZ表现为嵌入吸附在PLGA上,各基团表现出较好的理化特性。纳米纤维膜由原来的疏水逐渐变成亲水膜,拉伸性能随着甲硝唑含量增加逐渐减弱降低,有较好的热稳定性。结论在药物释放中,3wt%MNZ/PLGA膜缓释效果优于其它组。3wt%MNZ/PLGA膜有良好的生物相容性,多孔结构和高比表面积有利于细胞的吸附,有优越的力学性能,稳定持久的持续释放效果。MNZ/PLGA生物膜的制备为牙周炎的贴膜治疗优化方案提供了一定的理论支撑。