Star-shaped PCL/PLLA blended fiber membrane via electrospinning

Electrospun fiber mesh has been a candidate for guided bone regeneration membrane. However, its poor mechanics property has been limited in clinical application. In this study, various star-shaped poly(ε-caprolactones) (PCLs) are successfully synthesized by ring-opening polymerization and mixed with poly(l-lactide) (PLLA) to be made into blended membranes through electrospinning. Their corresponding properties are evaluated including morphology, thermodynamics, mechanics, and cytotoxicity. The blended fibers show smooth surface and well-distributed structure, which have slight differences in morphology with the change of arm number of star-shaped PCL. Crystallization of the fibrous membrane is influenced by star-shaped PCLs. Glass temperature drops from 64.23 °C for pure PLLA membrane to 53.62–49 °C for the blended membranes. The membranous tensile strength is depended strongly on star-shaped PCLs. The tensile strength goes up with arm number increasing; on the contrary, at the same arm number, the mechanics strength decreases with molecular weight increasing. And the fibrous membrane containing 20 wt.% star-shaped PCL shows better mechanics property compared to the other membranes. The star-shaped PCL/PLLA fiber membrane is not cytotoxicity.     

Synthesis and characterization of dendritic star-shaped zwitterionic polymers as novel anticancer drug delivery carriers

In this work, a novel dendritic star-shaped zwitterionic polymer, polyamidoamine-graft-poly[3-dimethyl (methacryloyloxyethyl) ammonium propanesulfonate] (PAMAM-g-PDMAPS), was synthesized. PAMAM dendrimers (generation 2, G2) were firstly prepared and then converted into the PAMAM-Br macroinitiator with 2-bromoisobutyryl bromide for ATRP. Finally, ATRP of zwitterionic DMAPS was carried out to obtain the dendritic star-shaped polymers PAMAM-g-PDMAPS with different PDMAPS chain lengths. Fourier transform-infrared spectroscopy, ¹H?NMR, dynamic laser light scattering (DLS), and TEM were used to characterize the polymers. Encapsulation of adriamycin (ADR) by PAMAM-g-PDMAPS nanoparticles and ADR release behavior from ADR-loaded PAMAM-g-PDMAPS nanoparticles were investigated in detail. PAMAM-g-PDMAPS polymers, even starting from low-generation PAMAM core (G2), were found to show high loading efficiency for ADR because ADR existed not only within G2 PAMAM cores but also in PDMAPS layers. The release profile of ADR from ADR-loaded PAMAM-g-PDMAPS nanoparticles was pH-sensitive and could be controlled by the length of PDMAPS chains. Cell viability studies indicated that ADR-loaded PAMAM-g-PDMAPS could effectively restrain the growth of HepG2 cells and even kill them, whereas PAMAM-g-PDMAPS exhibited nontoxicity. All these results demonstrated that dendritic star-shaped zwitterionic polymers PAMAM-g-PDMAPS are attractive candidates as anticancer drug delivery carriers.     

A novel star-shaped poly(carboxylic acid) for resin-modified glass-ionomer restoratives

We have developed a novel glass-ionomer cement (GIC) system composed of photo-curable star-shaped poly(acrylic acid-co-itaconic acid)s. These polyacids were synthesized via a chain-transfer radical polymerization using a newly synthesized multi-arm chain-transfer agent. The star-shaped polyacids showed significantly lower viscosities in water as compared to the linear polyacids. Due to the lower viscosities, the molecular weight (MW) of the polyacids can be significantly increased for enhancing the mechanical strengths while keeping the ease of mixing and handling. The effects of MW, GM-tethering ratio, P/L ratio, and aging on the compressive properties of the experimental cements were significant. The light-cured experimental cements showed significantly improved mechanical strengths i.e. 49% in yield strength, 41% in modulus, 25% in CS, 20% in DTS, and 36% in FS, higher than commercial Fuji II LC. After aging in water for 1 month, the compressive strength of the novel light-cured experimental cement reached 343?MPa, which was 34% and 42% higher than Fuji II and Fuji II LC, respectively. This one-month aged experimental cement was also 23% higher than itself after one day aging, indicating that aging in water can significantly enhance salt-bridge formation for this novel star-shaped polyacid-comprised GIC.     

溶液法星型聚乳酸的合成与表征

探讨了采用辛酸亚锡为催化剂,多元醇及多元酸为引发剂,以溶液法制备星型聚乳酸的可行性,研究了不同引发剂对产物分子量的影响。采用核磁共振及DSC对产物进行了表征,结果表明：以溶液法合成星型聚乳酸是可行的,但与丙交酯开环聚合制备星型聚乳酸的方法相比,溶液法在产物结构和分子量控制上并不十分有效,由于反应受到多官能团核引发剂空间位阻和反应概率的影响,聚乳酸产物的结构除星型结构外也同时存在大量的线型结构。     

Star-Shaped and Linear POSS-Polylactide Hybrid Copolymers

Novel octakis-2[(6-hydroxyhexyl)thio]ethyl-octasilsesquioxane (POSS-S-OH) as well as heptaisobutyl-2[(6-hydroxyhexyl)thio]ethyl-octasilsesquioxane (iBu-POSS-S-OH) were synthesized. POSS structures, bearing both types of groups i.e., 2[(6-hydroxyhexyl)thio]ethyl and the vinyl ones, pendant from the octahedral cage are also described. The synthetic pathway involved thiol-ene click reaction of 6-mercapto-1-hexanol (MCH) to octavinyloctasilsesquioxane (POSS-Vi), and heptaisobutylvinyloctasilsesquioxane (iBu-POSS-Vi), in the presence of 2,2′-azobisisobutyronitrile. The functionalized silsesquioxane cages of regular octahedral structure were used further as initiators for ring opening polymerization of l,l-dilactide, catalyzed by tin (II) 2-ethylhexanoate. The polymerization afforded biodegradable hybrid star shape and linear systems with an octasilsesquioxane cage as a core, bearing polylactide arm(s).     

星形聚合物胶束作为药物载体的研究进展

星形聚合物胶束是一类新型纳米药物载体,它具有独特的分枝结构,所形成的单分子胶束具有理想的粒径和稳定性,可使难溶性药物有效增溶,降低药物毒性,延长体循环时间,提高生物利用度和安全性。星形聚合物胶束作为药物载体具有良好的缓释效果,通过在聚合物表面接枝功能基团可产生靶向释放效果,聚酯结构的星形聚合物还具有良好的降解性能,不在体内蓄积产生毒副作用。本文对星形聚合物的合成及其胶束作为药物载体的理化性质、载药优势、制备方法等的研究进展进行综述。     

载姜黄素两亲性星状聚酯纳米粒的制备、表征及体外抗肿瘤研究

目的制备载姜黄素两亲性星状聚酯纳米粒(Cur-NPs),以解决其稳定性差、生物利用度低等问题。方法通过开环聚合反应和酯化反应合成两亲性星状聚酯(DPE-PCL-m PEG)作为纳米粒的载体材料,傅立叶变换显微红外光谱(FT-IR)、~1H-NMR和凝胶渗透色谱(GPC)表征确定其结构和相对分子质量。溶剂挥发法制备Cur-NPs,考察其粒径、ξ电位、载药量、包封率。对Cur-NPs进行稳定性、体外释放、材料安全性、体外抗肿瘤和细胞摄取能力考察。结果成功合成DPE-PCLm PEG,制备的Cur-NPs平均粒径为(86.00±2.01)nm,ξ电位为(-9.40±0.09)m V,包封率为(95.51±1.23)%,载药量为(5.52±0.54)%。Cur-NPs具有良好的稳定性和缓释能力。细胞毒性、细胞摄取和体外抗肿瘤实验表明,空白纳米粒(blankNPs)具有良好的生物安全性;相对于姜黄素溶液,Cur-NPs对人胶质瘤U251细胞的生长抑制作用更明显,并且具有更强的入胞能力。结论 Cur-NPs理化性质理想,能有效提高药物体外生物活性,为姜黄素的临床应用提供了新的解决方案。     

磷酸川芎嗪星型聚乳酸缓释微球的制备与体外释放研究

目的 制备磷酸川芎嗪星型聚乳酸载药微球,研究制备工艺参数对载药微球的药物包封率的影响,并对其体外释放特性进行表征。方法 以星型聚L-乳酸(sPLLA)为聚合物基材,采用复乳-溶剂挥发法制备磷酸川芎嗪(LP)星型聚乳酸载药微球(sPLLA/LP),采用正交试验优化处方,研究sPLLA/LP的体外缓释特性,并用FT-IR和SEM对微球进行表征。结果 通过极差分析与方差分析建立sPLLA/LP的药物包封率与制备工艺参数之间的关系,并在此基础上遴选出优化工艺。LP与sPLLA结合良好,sPLLA/LP微球缓释7 d后,sPLLA出现部分降解。采用优化工艺所制备的sPLLA/LP微球具有良好的缓释效果,SEM分析与缓释模型的拟合结果表明,0～48 h阶段的释药机制为药物扩散和聚合物降解协同作用;48～144 h阶段则主要为药物扩散释药。结论 采用复乳-溶剂挥发法制备的sPLLA/LP微球的药物包封率较高、体外释药平稳。     

肌醇为核的星形聚己内酯的制备及表征

目的制备六臂星形聚己内酯并评价其生物相容性。方法采用本体开环聚合法以ε-己内酯为单体,辛酸亚锡为催化剂,肌醇为多功能基团引发剂,合成一系列不同相对分子质量的六臂星形聚己内酯(6-s-PCLx)(其中x为单体与引发剂的摩尔比)。通过傅里叶红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)、差示扫描热分析法(DSC)对其结构、相对分子质量及热力学性质进行表征。以此材料为载体,采用超声乳化/溶剂挥发法,制备空白纳米粒。采用动态光散射法(DLS)和扫描电子显微镜(SEM)对其粒径和形态进行表征,通过WST-1比色法探讨该材料的体外细胞毒性。结果 FT-IR和1H-NMR表明,该聚合物为六臂星形结构;由GPC得出其相对分子质量分别为22 822、31 459、49 533,并呈单峰分布;DSC结果表明,聚合物的熔融温度(Tm)、熔融焓(ΔH)及结晶度(Xc)随着相对分子质量的增加而升高;制备的纳米粒呈椭圆形,平均粒径在100~200 nm,粒径均一;WST-1比色法证明,该材料具有良好的生物相容性。结论成功合成六臂星形聚己内酯并制备了纳米粒,细胞实验证明该材料具有良好的生物相容性。     

磷酸川芎嗪星型聚乳酸缓释微球的制备与体外释放研究

目的制备磷酸川芎嗪星型聚乳酸载药微球,研究制备工艺参数对载药微球的药物包封率的影响,并对其体外释放特性进行表征。方法以星型聚L-乳酸(sPLLA)为聚合物基材,采用复乳-溶剂挥发法制备磷酸川芎嗪(LP)星型聚乳酸载药微球(sPLLA/LP),采用正交试验优化处方,研究sPLLA/LP的体外缓释特性,并用FT-IR和SEM对微球进行表征。结果通过极差分析与方差分析建立sPLLA/LP的药物包封率与制备工艺参数之间的关系,并在此基础上遴选出优化工艺。LP与sPLLA结合良好,sPLLA/LP微球缓释7 d后,sPLLA出现部分降解。采用优化工艺所制备的sPLLA/LP微球具有良好的缓释效果,SEM分析与缓释模型的拟合结果表明,0~48h阶段的释药机制为药物扩散和聚合物降解协同作用;48~144 h阶段则主要为药物扩散释药。结论采用复乳-溶剂挥发法制备的sPLLA/LP微球的药物包封率较高、体外释药平稳。