Microspheres of essential oil in polylactic acid and poly(methyl methacrylate) matrices and their blends

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.     

Poly(ortho ester) nanoparticles targeted for chronic intraocular diseases: ocular safety and localization after intravitreal injection

Treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted by drug delivery to the back of the eye. In recent years, concerted efforts in drug delivery have been made to prolong the residence time of drugs injected in the vitreous humor of the eye. Our previous studies demonstrated that poly(ortho ester) (POE) nanoparticles were biodegradable/biocompatible and were capable of long-term sustained release. The objective of the present study was to investigate the safety and localization of POE nanoparticles in New Zealand white rabbits and C57BL/6 mice after intravitreal administration for the treatment of chronic posterior ocular diseases. Two concentration levels of POE nanoparticles solution were chosen for intravitreal injection: 1.5?mg/ml and 10?mg/ml. Our results demonstrate that POE nanoparticles were distributed throughout the vitreous cavity by optical coherence tomography (OCT) examination 14 days post-intravitreal injection. Intraocular pressure was not changed from baseline. Inflammatory or adverse effects were undetectable by slit lamp biomicroscopy. Furthermore, we demonstrate that POE nanoparticles have negligible toxicity assessed at the cellular level evidenced by a lack of glia activation or apoptosis estimation after intravitreal injection. Collectively, POE nanoparticles are a novel and nontoxic as an ocular drug delivery system for the treatment of posterior ocular diseases.     

蜂毒素微球经动脉介入治疗大鼠肝癌的实验研究

目的:观察蜂毒素微球(M-MS)经动脉介入对大鼠肝癌的治疗作用.方法:采用改良的复乳-液中干燥法制备蜂毒素-聚乳酸/羟乙酸微球,建立大鼠移植性肝癌模型并随机分为四组,分别经肝动脉灌注生理盐水(NS,1.5ml/kg)、蜂毒素(Melittin,0.35mg/kg)、空白微球(B-MS,10mg/kg)和蜂毒素-聚乳酸/羟乙酸微球(10mg/kg).比较治疗后各组大鼠的肿瘤生长情况、肿瘤坏死程度和生存时间.结果:与生理盐水组比较,Melittin组、B-MS组肿瘤生长受到明显抑制(P<0.01),肿瘤坏死程度以轻中度为主,但两组动物生存时间均未能明显延长(P>0.05).M-MS组与NS组、Melittin组及B-MS组相比,肿瘤生长抑制显著(P<0.01),肿瘤坏死更广泛、更彻底,且经蜂毒素微球治疗的大鼠生存期显著延长(P<0.01).结论:蜂毒素以药物微球的剂型经肝动脉给药,抗肿瘤效果明显优于单纯的蜂毒素和空白微球.     

甲壳素涂层PGLA神经导管修复兔面神经缺损的实验研究

目的:探讨甲壳素涂层PGLA神经导管修复兔面神经缺损的效果。方法:成年雄性新西兰兔24只,无菌条件下切断双侧面神经下颊支,制成15mm的兔面神经下颊支缺损模型。左侧用甲壳素涂层聚丙交脂-乙交脂共聚物[poly(L-lactide-co-glycolide),PGLA]神经导管修复;右侧用翻转自体神经修复作为对照。术后5周、10周和14周行大体观察、电生理检查、组织学、电镜观察评价修复效果。结果:术后5周观察到神经导管中有新生轴索通过,再生神经发育不成熟;右侧自体神经修复近段有髓神经纤维均匀疏散分布,远段未见明显再生神经束形成。术后14周左侧再生神经已通过神经导管长入远端,电生理检查结果表明自体神经修复侧再生神经质量优于神经导管修复侧,差异有统计学意义(P<0.01)。自体神经修复再生纤维密度优于神经导管修复侧,差异有统计学意义(P<0.01),但自体神经修复侧近段神经髓鞘部分空泡样变性及脱髓鞘改变,远段再生神经纤维束形成少,面肌联带运动程度较导管修复侧严重。结论:甲壳素涂层PGLA神经导管能有效修复周围神经缺损,有望替代自体神经移植。     

多官能度活性橡胶增韧环氧树脂的研究：Ⅲ.三元共混增韧环氧树脂

本文研究了双酚A对多官能度环氧基和羧基聚丙烯酸正丁酯橡胶增韧环氧树脂的影响。结果表明,加入双酚A,拉伸断裂能有大幅度提高,同时不降低弹性模量。这可能是由椽胶提高断裂伸长与双酚A提高屈服应力产生协同效应的结果。对羧基橡胶增韧的三元共混体系,拉伸断裂能随羧基官能度上升而增加。断裂面的形态研究表明,由于羧基橡胶与双酚A的酯化反应,大大减少了羧基橡胶聚集对增韧的不利影响。     

Calculation of Hydrolytic Rate Constants of Poly(ortho ester)s from Molecular Weights Determined by Gel Permeation Chromatography

Purpose. To obtained rate constants from weight-averaged (M_w) or z-averaged (M_z) molecular weights for polymers of Schule-Flory distribution and undergoing random scission. These constants were compared with those obtained by parallel ¹HNMR studies. Methods. The hydrolysis of two poly(ortho ester)s were followed by ¹HNMR and gel permeation chromatography (GPC). Results. Equations to convert number-averaged (M_n), M_w and M_z into fraction of backbone remaining (f_c) were derived. First-order hydrolytic rate constants of two poly(ortho ester)s; DETOSU-HD and DETOSU-CDM were calculated using these relationships. The rate constants calculated from ¹HNMR, M_z and M_w were 0.215, 0.218 and 0.182 hr^–1, respectively, for DETOSU-CDM and 0.152, 0.086 and 0.038 hr^–l for DETOSU-HD. The large discrepancy in the rates determined by ¹HNMR and GPC in the latter case was attributed to that the detector response (refractive index) of the monomers was lower than that of the high molecular weight polymer. The difference is small in the case of DETOSU-CDM, and the rates calculated from GPC data were comparable or nearly identical to that obtained from ¹HNMR data. Conclusions. Although GPC can yield rapid and valuable kinetic data for the degradation of biodegradable polymers, the system, however, must be carefully calibrated to account for the variations in Mark-Houwink coefficients and in the response of the mass detector between the high and low MW polymers.     

聚醚砜耐高温摩阻材料的研究

用热塑性聚(氧-1,4-亚苯基磺酰基-1,4-亚苯基)(聚醚砜)树脂作粘接剂,制备耐高温摩阻材料,探索了材料的压制工艺。试验证实了:聚醚砜树脂和制成的摩阻材料,其耐热性和摩擦磨损性能,较大程度优于改性酚醛树脂和其制成的材料。通过近代表面分析手段对摩擦表面和磨屑进行了分析,并探讨了其磨损机理。     

聚对苯撑乙炔的合成及光谱性能-共轭主链被间位苯环阻隔

报道了一种阻隔型聚对幕撑乙炔((PPE)的合成与电致发光特性，合成的模型小分子证明，在聚对苯撑乙炔(PPV)主链引入间位幕环，可阻隔PPV的有效共轭长度，改变其发光颜色，研究了电致发光暑件ITO／m-PPE／Al的电致发光特性。     

丁二酸酐交联羟基超支化聚(胺-酯)的反应及其交联膜的性质

以丁二酸酐(SA)为交联剂研究了端羟基超支化聚(胺-酯)(HPAE)的交联反应和交联膜的制备。结果表明:SA与HPAE的交联反应分为两个阶段,可以采用溶液法低温涂膜及高温交联得到HPAE/SA交联膜;改变SA的用量可控制膜的交联度,HPAE/SA交联膜的拉伸强度随SA用量的增大而提高,最高可达59.60 M Pa,膜表面的水接触角小于74.3°。