基于凝固浴剪切法制备多孔实心聚(乳酸-羟基乙酸)共聚物载药微球

以聚(乳酸-羟基乙酸)为基质材料,采用一种新颖的流动凝固浴剪切法制备包载盐酸万古霉素的载药微球,并研究微球的形貌结构、粒径、包封率、载药率、体外释放性能及其影响因素。结果表明,所制备的载药微球平均粒径在15~29μm范围,微球呈现内部实心表面多孔的复合结构;微球的包封率及载药可分别在15%~75%和1.5%~9.3%范围内调控。微球制备过程中的工艺条件对微球结构形貌、包封率、载药率及释放性能有重要影响,通过调整微球的粒径,可有效减缓释药过程中的突释现象。     

载紫杉醇聚乳酸-羟基乙酸纳米粒的体外释药研究

以生物可降解材料聚乳酸-羟基乙酸(PLGA)为载体制备了载紫杉醇纳米粒,重点考察了纳米粒的体外释放特性.采用乳化-溶剂挥发法制备了载紫杉醇PLGA纳米粒,其平均粒径为200nm,载药量为21%,包封率为89.44%;体外释药符合Higuchi方程:Q=3.8796t1/2+30.4649(r=0.9397),同时载紫杉醇纳米粒具有一定的缓释作用.     

药物缓释材料聚(乳酸-丙氨酸)的直接法合成与表征

直接以外消旋乳酸(LA)、L-丙氨酸(Ala)为原料[n(LA):n(Ala)=9:1],采用熔融聚合法合成药物缓释材料聚(乳酸-丙氨酸)共聚物[P(LA-co-Ala)],并用特性黏数、FTIR、1H NMR、GPC、DSC、XRD等手段进行系统表征.熔融共聚中采用一次投料并分次预聚,可生成重均相对分子质量(Mw)达3200(分散度Mw/Mn＝1.23)的共聚物,相对分子质量可以达到丙交酯开环共聚法的水平.首次报道了P(LA-co-Ala)]药物缓释材料的DSC与XRD表征结果,其与聚外消旋乳酸(PDLLA)相比,共聚物具有较低的Tg、Tm和结晶度.新方法步骤少、操作简便,且成本更加低廉.     

聚乳酸-羟基乙酸/改性纳米羟基磷灰石复合多孔支架材料的研制

聚乳酸-羟基乙酸(PLGA)/改性纳米羟基磷灰石(MHA)复合多孔组织工程支架材料的制备主要包含以下步骤:首先通过室温化学共沉淀法制备纳米羟基磷灰石,然后通过L-丙交酯在二甲苯溶液中聚合接枝纳米羟基磷灰石得到改性的纳米羟基磷灰石;最后通过改进的热致相分离两步初化法制备PLGA/MHA复合多孔支架.X射线衍射仪(XRD)显示纳米羟基磷灰石合成成功,透射电子显微镜(TEM)结果显示其为半径为30～50nm的球形,红外光谱显示聚乳酸成功的接枝到纳米羟基磷灰石表面;扫描电子显微镜(SEM)结果表明改进的热致相分离两步初化法制备的PLGA/MHA复合多孔支架的孔径在100～450μm.     

D,L-乳酸、L-乳酸、羟基乙酸的均聚物及共聚物的结晶性能研究

合成了高分子量的聚Ｄ,Ｌ－乳酸、聚Ｌ－乳酸、聚羟基乙酸、Ｄ,Ｌ－乳酸和共聚物以及乙酸和Ｄ,Ｌ－乳酸共聚物。以ＷＡＸＤ、ＦＴ－ＩＲ、ＤＴＡ表征了上述系列聚合物的结晶性能,分析了单体种类和共聚物中单体的比例对聚合物中结晶性能的影响,并对该系列聚合物的晶区结构作了描述。用万能拉力计测试了ＰＬＡ系列聚合物的力学性能,以ＤＴＡ测定了ＰＧＬＡ系列聚合物的热性能,探讨通过调整聚合物的组成以改变其结晶特性来调控聚     

生物降解材料聚羟基乙酸及其结晶性能研究

聚羟基乙酸(以下简称PGA)是一种单元碳数最少的脂肪族聚酯,集优异的气体阻隔性、生物兼容性和可降解性于一身,极具发展潜力的新型包装材料,也是较重要的医用生物降解材料。采用逐级提高真空度和逐级升温的先进工艺流程,选用高效、环保的新型络合钛溶液作为催化剂,直接缩聚法制备高分子量PGA,研究了PGA在DMSO中重结晶前后的性能特点及对比。     

人工神经支架材料聚（羟基乙酸-L-赖氨酸-乳酸）／NGF／β-TCP复合膜的制备及性能研究

通过对聚乳酸进行物理和化学改性，制备了一种用于神经修复的新型组织工程支架材料——霖（羟基乙酸-L-赖氨酸-乳酸）／NGF／β-TCP。采用FT-IR，^1H-NMR对中间产物和目标聚合物进行了表征。材料接触角的测试显示该材料亲水性较聚乳酸有明显改善；采用MTT实验检测细胞活性，其OD值明显高于对照组聚乳酸：通过免疫荧光观察细胞在材料表面的黏附与生长情况，结果显示嗅鞘细胞在该材料上生长形态及铺展状况良好。     

生物材料聚(乳酸-天冬酰胺)的制备与表征

以氯化亚锡为催化剂,L-乳酸(LA)与天冬酰胺(Asn)直接熔融聚合,所得生物材料聚(乳酸-天冬酰胺)[P(LA-co-Asn)]用[η]、红外光谱(FT-IR)、核磁共振(<'1>H-NMR)、凝胶渗透色谱(GPC)、差示扫描量热分析(DSC)、X射线衍射(XRD)等方法进行表征.随着投料比中Asn增加,共聚物由结晶...     

聚羟基乙酸及其共聚物的研究进展

本文综述了聚羟基乙酸的合成、性能、共聚改性等方面的研究进展 ,并讨论了聚羟基乙酸类材料的应用现状及前景     

纳米纤维素晶须增强增韧聚(L-乳酸)复合材料的制备与表征

通过酸解法制备了具有纳米尺寸和一定长径比针棒状的纳米纤维素晶须(NCW),利用NCW表面的羟基引发L-丙交酯开环聚合,合成了表面接枝聚(L-乳酸)(PLLA)链段的接枝纤维素晶须(g-NCW);采用溶液浇铸法制备了PLLA膜以及不同配比的NCW/PLLA和g-NCW/PLLA复合膜。对接枝改性前后的NCW的形貌与性能进行了表征,研究了复合膜的形貌、结晶性能、热稳定性、亲/疏水性和拉伸性能。结果表明:NCW的形貌与结晶性能在接枝改性后变化不大,但在乙醇和PLLA溶液中的分散性得到明显改善;当NCW与L-丙交酯的物质的量之比为1∶5时,g-NCW表面PLLA链段的接枝率约为23.61%。NCW和g-NCW作为异相成核剂,显著提高了PLLA基体的结晶速率;并且,加入晶须改善了材料的亲水性和热稳定性。添加一定量的NCW和g-NCW到PLLA中,可有效增强增韧PLLA基体;随着晶须含量增加,复合膜的拉伸强度和断裂能先增大后下降;当NCW和g-NCW的质量分数为5%时,NCW/PLLA和g-NCW/PLLA复合膜的拉伸强度和断裂能分别达到22.02 MPa和20.01 MPa以及102.39J/m~3和117.83J/m~3,均达到最大值。由于g-NCW在基体中良好的分散性以及与基体间的界面结合,g-NCW/PLLA复合膜的拉伸强度和韧性明显优于相应的纯PLLA和NCW/PLLA膜。     

静电纺丝天然-人工合成聚合物复合纳米纤维及其对细胞黏附、增殖和迁移的影响

生物材料组成成分对细胞生物功能有不同的影响。利用静电纺丝技术制备了基于聚己内酯(PCL,polycaprolactone)的不同天然蛋白、多糖(丝素蛋白(SF,silk fibroin)、透明质酸(HA,hyaluronicacid))的混合组分纳米纤维,采用了扫描电镜和接触角对纳米纤维进行基础表征。同时,进一步考察了纳米纤维作为组织工程支架的可行性。研究结果表明SF组分能增加材料的可纺性,有利于细胞的前期黏附,并能够促进细胞增殖。HA组分可以改善材料的亲水性,增加细胞伪足并促进细胞迁移。重要的是,PCL/SF/HA纳米纤维能同时结合SF和HA的优点,有望在组织工程领域得到应用。     

聚羟基乙酸接枝淀粉共聚物的合成和性能

以乙交酯和淀粉为原料,三乙胺为催化剂,在二甲基亚砜介质中合成了聚羟基乙酸接枝淀粉共聚物。讨论了原料配比和反应时间对共聚物接枝率(G)、接枝效率(E)和单体转化率(C)的影响。采用核磁共振谱仪(1H-NM R)、傅立叶变换红外光谱仪(FT-IR)、X射线粉末(多晶)衍射仪(XRD)、差式扫描量热仪(DSC)以及体外降解试验,研究了接枝共聚物的结构和性能。实验结果表明,将乙交酯单体和淀粉接枝共聚,可以得到一类新的可降解聚合物。     

Synthesis and in vitro release study of ibuprofen-loaded gelatin graft copolymer nanoparticles

Objective: This work deals with the preparation, characterization and in vitro release study of IBU-loaded gel graft copolymer nanoparticles.

Method: Gelatin (Gel) graft copolymer nanoparticles were prepared using styrene (Sty) and/or 2-hydroxyethyl methacrylate (HEMA) monomers in the presence of potassium persulfate and glutaraldehyde as an initiator and cross-linker, respectively. The prepared nanoparticles as sustained release drug carriers were investigated using the nonsteriodal anti-inflammatory model drug, ibuprofen (IBU).

Results: The prepared nanoparticles as sustained release drug carriers were investigated using the nonsteriodal anti-inflammatory model drug, IBU. The prepared Gel/HEMA and Gel/Sty nanoparticles exhibited particles size ranging from 15 to 17?nm and from 0.42 to 5?mm, respectively. The dissolution of IBU in phosphate buffer, pH 7.4, at 37°C from the prepared nanoparticles was evaluated using UV spectroscopy. In addition, the prepared nanoparticles were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), transmitting electron microscope (TEM) and zeta potential/particle size analyzer. In vitro dissolution study showed that the dissolution rates of the crosslinked nanoparticles were retarded relative to the uncrosslinked ones. Moreover, the released amount constantly decreases with increasing gluteraldehyde content in the gel nanoparticles.

Conclusion: Crosslinked gel-based graft copolymers exhibited slow IBU release within six hours. Furthermore, results from different characterization techniques such as TEM, particles size and zeta potential measurements confirmed the formation of pH-responsive gel-graft copolymer nanoparticles.     

Interpolymer complexation between copovidone and carbopol and its effect on drug release from matrix tablets

The interaction between copovidone and Carbopol 907 is pH dependent. When the pH of an aqueous solution fell below pH 4.5, a water-insoluble complex began to form and precipitate. This complex resulted from a hydrogen-bond-induced interaction between the carboxylic groups in Carbopol 907 and the carbonyl groups of N-vinylpyrrolidone repeat units in copovidone. Consisting of these two polymers at an approximate 1:1 weight ratio, the complex was an amorphous material with a glass transition temperature of 157?°C. The interpolymer complexation in situ was applied to modify drug release properties of Carbopol 907-based theophylline matrix tablets. The effect of copovidone on drug release was dependent on the pH of the dissolution medium. In a 0.1 N hydrochloride acid solution at pH 1.2 and 50?mM acetate buffer at pH 4.0, an insoluble tablet matrix was formed as a result of the in situ interpolymer complexation, and theophylline was released therefore via Fickian diffusion. In a 50?mM phosphate buffer at pH 6.8, drug release from the matrix tablets was still impacted by the in situ interpolymer complexation because of the low-pH microenvironment induced by Carbopol 907. As a result, drug release rate of the matrix tablet containing both polymers at pH 6.8 was slower than that of the matrix tablets containing individual polymers. We observed similar drug release rates at both pH 1.2 and pH 6.8 between tablets containing the physical blend of these two polymers and tablets containing preformed interpolymer complexes.     

PLGA/TSF静电纺纳米纤维的仿生矿化及生物相容性

利用静电纺丝和模拟体液仿生矿化技术制备了聚乳酸-羟基乙酸共聚物/柞蚕丝素/羟基磷灰石((PLGA/TSF/HA)骨组织工程复合支架。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射测试(XRD)和热重分析(TG)对复合纳米纤维的形貌结构进行了表征。此外,在复合纳米纤维支架材料上接种人骨髓间充质干细胞(hMSCs),通过四甲基偶氮噻唑蓝比色(Four methyl azo thiazole blue colorimetric,MTT)法,观察细胞在材料表面的生长情况评价纳米纤维的生物相容性。结果显示,PLGA/TSF纳米纤维毡具有精细的三维结构,纤维直径分布均匀,表面光滑。矿化后HA颗粒均匀地分布在PLGA/TSF纳米纤维表面,矿物含量约占63%。与PLGA/TSF纳米纤维支架相比,PLGA/TSF/HA纳米纤维支架的亲水性、生物相容性都得到显著提高。     

纳米碳纤维表面修饰及其在水溶液中的分散

为了研究纳米碳纤维(CNFs)在水溶液中的分散情况,对其进行高温纯化处理,以甲基纤维素(MC)为分散剂,制备分散良好的CNFs悬浮液.采用差热分析(DTA)和热重分析(TGA)研究了高温处理对CNFs的影响,通过测定悬浮液的紫外可见光吸光度、等温吸附曲线、zeta电位及表面张力等方法研究了MC对CNFs分散性能的影响,并讨论分析了MC对CNFs的分散机理.结果表明:MC的加入使CNFs悬浮液的zeta电位由-15.4 mV升至0,表面张力由38.87 mN/m降至36.54 mN/m;等温吸附曲线表明MC在CNFs的表面为"单阶段吸附",当MC的质量浓度达到0.4 g/L时,MC在CNFs表面饱和吸附;当CNFs达到最佳分散状态时,MC与CNFs的质量比为2∶1.     

聚乳酸/杆菌肽静电纺丝纤维的体外释药研究

为探讨聚乳酸纤维结构形貌对杆菌肽药物的缓慢释放行为及作用机理,通过静电纺丝法制备了聚乳酸/杆菌肽单轴纤维、聚乳酸/杆菌肽串珠和(聚乳酸/杆菌肽)-聚乳酸同轴核-壳纤维等聚乳酸/杆菌肽药物缓释体系,并采用红外光谱法和差热分析法对其化学结构和热性能进行了表征.利用紫外分光光度计法研究了不同载药体系的体外药物释放行为,并探索了不同降解时期载药纤维的质量和形貌变化规律.研究表明:杆菌肽与聚乳酸主要为物理结合;聚乳酸单轴纤维和串珠对杆菌肽的扩散释放机理,属于纯Fick扩散;采用单轴和同轴静电纺丝技术可以获得两种不同释药特性的载药纤维.单轴纤维和串珠能够将药物快速释放,适合抗生素的治疗;同轴纤维中药物受控释放,更适合长期、小剂量的药物释放.     

Reduction in the initial-burst release by surface crosslinking of PLGA microparticles containing hydrophilic or hydrophobic drugs

Sustained-release approaches are emerging for the delivery of drugs from polymer encapsulation. However, the most persistent problem that remains is the initial burst release of the drug, which can exceed the toxic limits. Dexamethasone, a hydrophobic drug, was encapsulated in poly(lactide-co-glycolide) (PLGA) microparticles using the solvent evaporation method. The drug release profile of these microparticles was studied and the initial burst was reduced by crosslinking of the microparticle surface using ethylene glycol dimethacrylate and tri(ethylene glycol) dimethacrylate. Due to surface crosslinking, an additional diffusional resistance was created, which prevented easy dissolution of the drug into the release medium and brought about a substantial reduction in the initial burst release. Moreover, the time required for reaching a stationary-state release was also observed to be delayed, prolonging the sustained drug delivery. This concept was further tested with a hydrophilic drug, the sodium salt of dexamethasone phosphate, encapsulated in PLGA polymer microparticles and was observed to reduce the burst release as well. For synthesizing the polymer microparticles containing dexamethasone, an o/w microemulsion and solvent evaporation technique was used; whereas, for those containing dexamethasone phosphate, w/o/o/o phase separation/coacervation technique was used. The surface crosslinking was performed by ultraviolet radiation.     

静电纺丝法制备聚丙烯腈基纳米炭纤维及其表面结构表征

通过稳定化、炭化静电纺制的聚丙烯腈(PAN)前驱体纤维制备了直径为100nm～300nm的纳米炭纤维.用扫描电镜(SEM)、场发射扫描电镜(FESEM)、扫描隧道显微镜(STM)及扫描量热分析法(DSC)研究了纳米炭纤维及其前驱体纤维的形貌及结构.结果表明:纳米炭纤维及其前驱体纤维的直径表现为对数正态分布.静电纺制纤维的环化放热峰移向低温,表明静电纺制纤维可在较低的温度下引发环化.由于静电纺制纤维的粗糙表面及在热处理过程中的收缩行为,在纳米炭纤维表面形成了长度为10nm宽度为5nm的凹坑.     

In situ forming implants for the delivery of metronidazole to periodontal pockets: formulation and drug release studies

This study was performed to obtain prolonged drug release with biodegradable in situ forming implants for the local delivery of metronidazole to periodontal pockets. The effect of polymer type (capped and uncapped PLGA), solvent type (water-miscible and water-immiscible) and the polymer/drug ratio on in vitro drug release studies were investigated. In situ implants with sustained metronidazole release and low initial burst consisted of capped PLGA and N-methyl-2-pyrolidone as solvent. Mucoadhesive polymers were incorporated into the in situ implants in order to modify the properties of the delivery systems towards longer residence times in vivo. Addition of the polymers changed the adhesiveness and increased the viscosity and drug release of the formulations. However, sustained drug release over 10 days was achievable. Biodegradable in situ forming implants are therefore an attractive delivery system to achieve prolonged release of metronidazole at periodontal therapy.