新型生物可降解交联N—乙烯基吡咯烷酮（NVP）材料的制备

用甘油和丙交酯在辛酸亚锡的催化下合成了可降解的三羟基中间体，在三乙胺存在的条件下，末端用丙烯酰氯进行功能化，合成了可降解的三乙烯基交联剂，并且对中间体和交联剂进行了FTIR，^1H-NMR,GPC分析表征。这种交联剂与乙烯基吡咯烷酮（NVP）用偶氮二异丁氰（AIBN）为引发剂自由基引发聚合制备了组织工程支架材料，并且对材料的基本性能（吸水率和接触角）进行了分析表征。     

生物可降解交联剂对PVP膜性能的影响

本研究在制备了一系列可降解的三乙烯基交联剂的基础上，利用偶氮二异丁氰(AlBN)引发该交联剂与N-乙烯基吡咯烷酮(NVP)交联。重点研究了交联剂含量及分子量对材料的吸水率、接触角利降解性能的影响。结果表明交联膜材料的接触角随着交联剂含量的增加而逐渐增加，而吸水率和材料的降解速率却逐渐减小；随交联剂分子量的增加，材料的吸水率是逐渐增加但对接触角的影响不大，材料的降解速率随交联剂分子量的增加而增大。     

新型角膜支架材料的制备及生物相容性研究

首先合成了一种新型可降解的三乙烯基交联剂,并以偶氮二异丁氰(A IBN)为引发剂与乙烯基吡咯烷酮(NVP)通过自由基聚合制备了一种新型的交联NVP角膜支架材料。对材料的吸水率、接触角和降解性能进行了测定,通过体内埋植实验和细胞培养对材料进行了生物相容性评价。结果表明材料的吸水率达到104%,接触角为41,°降解速率较为恒定;体内埋植实验研究表明,3个月后,材料已大部分降解,材料内出现胶原和角膜基质细胞,周围组织无明显的炎症反应;细胞培养实验表明,角膜上皮细胞在材料上可以较好的生长,没有明显的细胞毒性,具有良好的生物相容性,这种合成的新型交联NVP角膜支架材料将在角膜组织工程中具有潜在的应用价值。     

聚甲基丙烯酸羟乙酯水凝胶人工晶状体材料的合成与性能

以甲基丙烯酸羟乙酯为原料,过硫酸铵/偏重亚硫酸钠为引发体系,二甲基丙烯酸三乙二醇酯为交联剂,采用溶液聚合法制备了聚甲基丙烯酸羟乙酯水凝胶(PHEMA)人工晶状体材料。系统考察了聚合反应时间、温度及引发剂和交联剂的用量等对该水凝胶材料机械强度、平衡水含量(EWC)的影响,并对PHEMA水凝胶的结构和光学性能进行了表征。实验结果表明,PHEMA水凝胶的最佳合成条件为:引发剂0.5wt%,交联剂1.0wt%,反应温度40℃,反应时间36h。在此条件下制备的PHEMA水凝胶的拉伸强度达到0.57MPa,邵氏A硬度为23.0,平衡含水量超过40%,透光率≥97%。     

可降解聚甲基丙烯酸二甲基胺乙酯三维网络;合成、表征、体外降解及细胞毒性

在眼科医疗中,需要使用可降解生物材料制备药物缓释体系用于玻璃体内。这类材料应有良好的生物相容性和确定的生物降解动力学。聚交酯(如PLA、PLGA等)已被广泛应用,但其降解产物会催化降解反应,降解过程难以控制。本工作研究了一种新型的可降解高分子体系——聚甲基丙烯酸二甲基胺乙酯三维网络。体系的制备是将甲基丙烯酸二甲基胺乙酯单体与一定比例带双甲基丙烯酸酯基的交联剂和光引发剂混合后紫外光辐照得到。用动态力学分析DMTA及NMR,SEM、FT-R对体系进行表征,并研究了体系在不同pH值环境下的降解行为。研究显示,体系内均匀交联…     

pH敏感含糖三元共聚水凝胶Poly(AM-CO-IA-VBG)的药物释放性能研究

用4-乙烯基苄基胺与葡萄糖内酯反应合成了4-乙烯苄基葡萄糖酰胺单体(VBG)。以亚甲基双丙烯酰胺(BisA)为交联剂,用过硫酸钾(KPS)引发丙烯酰胺(AM)、衣康酸(IA)及4-乙烯苄基葡萄糖酰胺使之共聚,得到pH敏感含糖结构的三元共聚水凝胶。用核磁共振及红外光谱对单体和水凝胶的结构进行了表征,研究了不同水凝胶中药物的释放性能,以及pH值及盐的浓度对水凝胶中药物释放的影响。结果表明:水凝胶中药物在低pH值时或盐中药物释放显著下降,表明水凝胶对酸或盐有强烈的响应性。     

聚乳酸及其复合材料的研究进展

1引言聚乳酸(PLA)是一种具有良好生物相容性的生物降解材料,在体内可降解成乳酸,进入三羧酸循环,最终产物是CO2和H2O,对人体无毒无害,是当前医学上应用最多的合成可降解聚合物之一。它在医用领域中广泛应用为药物缓释材料、体内植入材料、手术缝合线、骨科固定材料以及组织工程材料等。聚乳酸可以通过乳酸的缩聚或丙交酯的开环聚合制备。乳酸是手性分子,     

菌蚀型生物降解材料的合成与表征

本文力图设计与合成在人体结肠厌氧菌存在环境下,可被微生物降解的生物材料.用三种亲疏水性不同、软硬段不同的三种单体,即甲基丙烯酸羟乙酯(HEMA)、甲基丙烯酸(MAA)、甲基丙烯酸甲酯(MMA)为载体,并用对甲基丙烯酰胺偶氮苯(BMAAB)为偶联剂,合成了聚甲基丙烯酸羟乙酯-甲基丙烯酸甲酯-甲基丙烯酸[P(HEMA-MMA-MAA)]三元偶氮聚合物.用红外、紫外、核磁共振进行化学结构表征,并测定了该材料的溶胀性能,比较了聚合物降解前后分子量、热性能与形态变化.结果证明材料的降解程度与材料中亲水组分含量直接相关.     

可降解扩链PLA聚合物拉伸强度的研究

目的探讨影响可降解骨内固定材料扩链PLA(聚丙交酯)聚合物拉伸强度的因素。方法根据国家GB-9641—88标准，将扩链PLA聚合物制成哑铃形试样，在不同温度、时间、扩链剂、交联剂、分子量条件下(聚丙交酯：聚己内酯=l：4)，用高分子万能试验机以5mm／min的拉伸速度测出拉伸强度。结果在扩链反应中的混合温度、混合时间、变定温度、变定时间、扩链剂、交联剂及端羟基聚丙交酯分子量大小对扩链PLA聚合物的拉伸强度均有影响。结论在聚丙交酯：聚己内酯=l：4时，混合温度为100％、混合时间为4min、变定温度为130℃、变定时间为6h、A扩链剂、交联剂-l及端羟基聚丙交酯分子量为300时，其拉伸强度最大，为24．47MPa。     

生物可降解性消化道支架的应用及其生物相容性

背景：生物可降解支架可在消化道管腔内短期成形,具有良好的生物相容性,随后完全降解,并可以根据临床需要调节支架降解时间,避免了永久性支架的并发症。 目的：评价不同材料制成的生物可降解性消化道支架的应用、相容性评价以及研究进展。 方法：以 “生物可降解,消化道,支架,相容性” 为关键词,采用电子检索方式在万方数据库中检索1999-01/2009-12有关生物可降解性消化道支架的研究。排除重复研究、普通综述或Meta分析类文章,筛选纳入22篇文献进行评价。 结果与结论：可降解支架在消化道疾病中的应用已经显示其有效的扩张性及临床安全性等。可降解材料大多是高分子材料,包括天然可降解高分子、微生物合成高分子材料和合成可降解高分子3类。天然可降解高分子大多是多糖类。天然可降解高分子一般生物相容性良好,但是力学性能较差。微生物合成高分子材料目前研究及应用尚较少。合成高分子种类比较多,常见的有聚丙交酯、聚己内酯、聚乙二醇等。合成高分子优点在于可以比较灵活的设计分子结构,通过发展共聚物、共混物来得到不同性质的材料。可降解支架可以解决良恶性狭窄的再通及瘘口的封堵等,但可降解支架在消化道系统中应用的效力还需要未来进行大量的研究工作来评估。     

High strength bioresorbable bone plates: preparation, mechanical properties and in vitro analysis

Biodegradable bone plates were prepared as semi-interpenetrating networks (SIPN) of crosslinked polypropylene fumarate (PPF) within a host matrix of either poly(lactide-co-glycolide)-85:15 (PLGA) or poly(1-lactide-co-d,l-lactide)-70:30 (PLA) using N-vinylpyrrolidone (NVP), ethylene glycol dimethacrylate (EGDMA), 2-hydroxyethyl methacrylate (HEMA), and methyl methacrylate (MMA) as crosslinking agents. Hydroxyapatite (HAP), an inorganic filler material, was used to further augment mechanical strength. The control crosslinking agent (NVP) was replaced partially and totally with other crosslinking agents. The amount of crosslinking agent lost, the characterization change in the mechanical properties and the dimensional stability of the bone plates after in vitro treatment was calculated. The optimum crosslinking agent was selected on the basis of low in vitro release of NVP from SIPN matrix. Bone plates were then prepared using this crosslinking agent at 5 MPa pressure and at temperatures between 100-140 degrees C to determine if there was any augmentation of mechanical properties in the presence of the crosslinked network. In vitro analysis showed that 90% of the crosslinking agent was lost on plates using NVP as a crosslinking agent. This loss was reduced to 50% when NVP was partially replaced with EGDMA or MMA. EGDMA was determined to be superior because (1) its low release as a crosslinking agent, (2) flexural plate strength of 50-67 MPa, (3) flexural modulus of 7-13 GPa, and (4) manufacturability stiffness of 300-600 N/m. HAP-loading resulted in an additional increase in values of mechanical parameters. Substituting PLGA with PLA in the PPF-SIPN did not show any additional improvement of mechanical properties.     

Photopolymerization and shrinkage kinetics of in situ crosslinkable N-vinyl-pyrrolidone/poly(epsilon-caprolactone fumarate) networks

Biodegradable, injectable and in situ photocrosslinkable macromers based on fumaric acid and polycaprolactone (PCLF) were prepared and characterized by FTIR, 1HNMR, and 13CNMR spectroscopy. The multifunctional macromers dissolved in N-vinyl pyrollidone (NVP) were photopolymerized by visible light irradiation in the presence of camphorquinone as photoinitiator. The photocrosslinking reaction was monitored by measuring shrinkage strain and shrinkage strain rate. The degree of photopolymerization reaction i.e. degree of conversion (DC%) was traced using FTIR spectroscopy. A three level factorial design was developed to study the effects of initiator concentration, NVP concentration, and molecular weight of PCLF upon photocrosslinking characteristics including degree of conversion and shrinkage strain. Results revealed that although neat PCLF was photopolymerized, but it was putty like after 220 seconds of irradiation and showed a very low degree of conversion (29%). Adding about 20% NVP caused a dramatic increase in its degree of conversion (63.33%). Increasing NVP up to 50% resulted in a decrease in DC% because of lower reactivity of NVP and leaving more unreacted NVP monomers. Sol fraction studies supported these results indicating that at higher NVP concentration, most of NVP and PCLF have not undergone the crosslinking reaction, leading to 55% decrease in DC%. Shrinkage strain measurement also confirmed the FTIR results.     

Injectable in situ forming drug delivery system based on poly(ε-caprolactone fumarate) for tamoxifen citrate delivery: Gelation characteristics,in vitro drug release and anti-cancer evaluation

The present study deals with the preparation and characterization of an injectable and in situ forming drug delivery system based on photocrosslinked poly(ε-caprolactone fumarate) (PCLF) networks loaded with tamoxifen citrate (TC). Networks were made of PCLF macromers, a photoinitiation system (comprising initiator and accelerator) and the active ingredient N-vinyl-2-pyrrolidone (NVP) as a crosslinker and reactive diluent. Shrinkage behavior, equilibrium swelling and sol fraction ratios of photocrosslinked PCLF gels were determined as functions of NVP content. It was shown that the crosslinking is facilitated up to a certain concentration of NVP and most of NVP remained unreacted above this value. In vitro drug release, biocompatibility evaluation and activity against MCF-7 breast cancer cell line were also investigated. Accurate but simple bipartite expressions were also derived that enable rapid determination of effective diffusion coefficients of TC in photocrosslinked PCLF/NVP disks. Cytotoxicity assay showed that while the photocrosslinked PCLF network with optimum NVP content exhibits no significant cytotoxicity against MCF-7 and L929 cell lines, 40–60% of the MCF-7 cells were killed after incubation with TC-loaded devices.     

不同交联度的医用级壳聚糖的降解研究

目的：研究不同交联度的医用级壳聚糖在体内、体外的降解性。方法：通过体外酶解试验和动物体内植入试验研究不同交联度的医用级壳聚糖的降解性能。结果：壳聚糖的降解速度随着交联度的增大而减慢。结论：壳聚糖是一种可生物降解材料，其交联度的大小直接影响其降解速度。     

Multistructured Nanogel‐Based Networks Formed from Interfacial Redox Polymerizations for Modulating Small Molecule Release

Uniform, 3D nanogel‐based coatings are generated on polymeric substrates using an interfacial redox polymerization. Diffusion of a reducing agent from a core material into a solution of acrylate‐functionalized nanogels and an oxidizer generates free radicals that initiate nanogel crosslinking selectively at the gel surface. Coating thickness is controlled between 20 and 150 µm by varying reaction time and initiator concentration. Controlling the structure of the final nanogel‐based coating is demonstrated to predictably change the diffusion coefficient of a small molecule drug loaded into the core material. Multidrug release from the coating and the core is demonstrated with model dyes. This study showcases the ability to design multifunctional networks for controlled release using a simple, mild coating procedure.     

Kinetische analyse der copolymerisationsgeschwindigkeit von N-vinyl-2-pyrrolidon mit styrol und methylmethacrylat

The polymerization rate of two binary monomer systems styrene (St)/N-vinyl-2-pyrrolidone (NVP) and NVP/methyl methacrylate (MMA) was investigated dilatometrically in bulk at 60°C with AIBN as initiator. While the copolymerization rate of the system St/NVP can be satisfactorily described by means of the classical reaction model, this is not the case for the system NVP/MMA. This deviation from the classical model can be explained by a charge-transfer interaction between NVP and MMA which was measured by means of ¹H and ¹³C NMR spectroscopy.     

Creating porous tubes by centrifugal forces for soft tissue application

Chemically crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) tubes were synthesized by applying centrifugal forces to propagating polymer chains in solution. Initiated monomer solutions, with a composition typical for PHEMA sponges, were placed into a cylindrical mold that was rotated about its long axis. As polymerization proceeded, phase separated PHEMA formed a sediment at the periphery under centrifugal action. The solvent remained in the center of the mold while the PHEMA phase gelled, resulting in a tube. By controlling the rotational speed and the formulation chemistry (i.e., monomer, initiator and crosslinking agent concentrations), the tube dimensions and wall morphology were manipulated. Tube manufacture was limited by a critical casting concentration [M]c, above which only rods formed. All tubes had an outer diameter of 2.4 mm, reflecting the internal diameter of the mold and a wall thickness of approximately 40-400 microm. Wall morphologies varied from interconnecting polymer and water phases to a closed cell, gel-like, structure. Concentric tubes were successfully prepared by using formulations that enhanced phase separation over gelation/network formation. This was achieved by using formulations with lower concentrations of monomer and crosslinking agent and higher concentrations of initiator. This technique offers a new approach to the synthesis of polymeric tubes for use in soft tissue applications, such as nerve guidance channels.     

Free‐radical crosslinking polymerization of unsymmetrical divinyl compounds, 1 Gelation in the polymerization of allyl methacrylate

As an extension of our continuing studies concerned with the free‐radical crosslinking polymerization of multivinyl compounds, this article deals with the gelation in the polymerization of allyl methacrylate (AMA) as a typical unsymmetrical divinyl compound containing two types of vinyl groups such as methacryloyl and allyl ones having quite different reactivities. Thus, AMA was polymerized in bulk or in a 1,4‐dioxane solution using an azo‐initiator at 50°C in the presence of lauryl mercaptan as chain transfer agent. The actual gel point was compared with the calculated one according to Gordon's equation by tentatively supposing equal reactivity of both vinyl groups. Tailed molecular‐weight distribution curves were observed. The swelling ratios of the resulting gels obtained just beyond the gel point was very high. Thus, the intermolecular crosslinking occurred predominantly in the bulk polymerization. Even in the solution polymerization, the occurrence of intramolecular crosslinking was only a little. This was supported by the r.m.s. radii of gyration and second virial coefficients of resulting prepolymers.