核酸标准物质定值的实验体系研究

分子体外诊断技术的高速发展,市场对不同种类具有溯源性的核酸标准物质的需求越来越迫切。然而,核酸种类的多样性给标准物质的研制带来了不小的困难。但核酸物理化学特性相近,定值过程有诸多共同点。从核酸取样量、核酸的稀释、定值方法的选择和数据结果分析4个方面详细地阐述了核酸标准物质在定值实验过程中涉及到的关键因素。通过分析得出,核酸定值的关键在于样品取样量、上样浓度和最佳定量范围的确定,从而建立正确的实验体系,减小核酸定值过程中产生的实验误差,避免错误的结果。     

Biodegradability of poly(ethylene terephthalate) copolymers with poly(ethylene glycol)s and poly(tetramethylene glycol)

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10–40mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200–7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T_m), cold crystallization and glass transition (T_g) decreased with the copolymerization. T_m depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. T_g was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.     

聚丙交酯-乙交酯聚合物(PLGA)涂层体外降解行为研究

为了防止心血管支架植入后再狭窄的发生,目前采用将抑制平滑肌细胞生长的药物通过高分子载体涂在支架表面.由于支架植入体内后,涂层受到血液冲刷作用.本工作采用可降解高分子材料PLGA作为载体,将PLGA薄膜置于体外循环冲刷装置中,在37℃、pH7.4的Hank's模拟体液、模拟血流冲刷作用下的体外降解,并与静态降解作为对比.采用SEM、GPC、1H-NMR和DSC技术研究了聚合物在降解过程中形貌、分子量及分子量分布、失重率、组成和热性能的变化,并对降解机理进行探讨.与静态降解相比较,在流动体液中,高分子载体表面形貌、失重率以及分子量变化均较慢.上述结果与表面微环境有关.     

应用于化妆品的水杨酸微胶囊载体系统的制备及表征

以阿拉伯胶和麦芽糊精为微胶囊壁材,采用喷雾干燥法制备水杨酸微胶囊,并用傅里叶红外光谱及扫描电子显微镜对包埋行为进行鉴定,还研究了最佳阿拉伯胶／麦芽糊精比、微胶囊溶解度、释放机制及体外透皮性,实验结果表明,最佳阿拉伯胶／麦芽糊精比为1：1,微胶囊化后水杨酸溶解度能够提高至26mg/mL。水杨酸微胶囊呈现球状结构,并具有一定的缓释性,体外透皮结果显示微胶囊化后水杨酸透皮速率减慢并且无突释现象,与未包埋水杨酸相比,水杨酸微胶囊具有更高的皮表保留量和较低的皮肤驻留量。     

Plasticizing effect of ibuprofen induced an alteration of drug released from Kollidon SR matrices produced by direct compression

The objectives of this study were to investigate the effect of storage temperature on drug release from matrices containing 10, 40 and 70% w/w ibuprofen in Kollidon® SR (KSR). The matrix tablets were produced by direct compression and then kept at 30 and 45?°C for 3 months. Drug release from the matrix tablets was examined after storage for 0, 1, 4 and 12 weeks. Scanning electron microscope was used to reveal physical appearance of the tablet surface at the respective time intervals. In addition, differential scanning calorimeter was used to investigate glass transition temperature (T_g) of ibuprofen in KSR at 0–100% w/w based on the principle of Gordon–Taylor equation. At 45?°C, the dissolution of ibuprofen in KSR as well as the coalescence of polymer particles were observed to be higher than those of storage at 30?°C. The physical state of ibuprofen dispersed in the polymeric matrix and degree of polymer coalescence led to the variation of drug release. The coalescence of polymer particles was a result of the polymer transition from glassy to rubbery state according to water absorption of KSR and plasticizing effect of ibuprofen. The reduction of the T_g of ibuprofen blended with KSR could be better described by the Kwei equation, a modified version of Gordon–Taylor equation.     

Resistance of the kidney bean reserve protein,phaseolin, to proteolysis in the porcine digestive tract

Abstract : Phaseolin, the major reserve protein of the seeds of the kidney bean, Phaseolus vulgaris L, was shown to be poorly degraded in the pig small intestine following an initial 7-day exposure to casein-based diets incorporating kidney bean meal. Substantial amounts of large polypeptide fragments, which were recognised by antibodies raised against native phaseolin, were identified in ileal digesta. Little of this immunoreactivity was detected in the faeces of these animals, suggesting that components of the hindgut microflora were able to degrade these fragments further. Prolonged exposure to dietary kidney beans resulted in an increase in the digestibility of phaseolin, suggesting that the small intestine and/or its microflora may possess significant adaptive capacity. In-vitro digestion of purified phaseolin by a sequence of pepsin, trypsin and chymotrypsin yielded products which closely resembled those isolated from the ileal digesla; analysis suggested that degradation of native phaseolin by the major gastrointestinal endopeptidases is restricted to a vulnerable central region of its constituent polypeptides.     

CHEMICAL AND TOXICOLOGICAL CHARACTERIZATION OF AIRBORNE TOTAL SUSPENDED PARTICULATE (TSP) AND PM 10 ORGANIC EXTRACTS

The relationship between chemical composition of airborne particulates and the genotoxicity has been investigated in the atmosphere of Rome, Italy. For this purpose, both total suspended particulate (TSP) and the PM ₁₀ fractions were collected daily inside a green park located in downtown, grouped on a weekly basis and speciated for their burdens of polycyclic aromatic hydrocarbons (PAH) and nitro-PAH. Concurrently, the genotoxicity of the organic extracts was evaluated by the Comet assay (SCGE: single cell gel electrophoresis) on human peripheral blood mononuclear cells (PBMC). The results indicate that organic extracts were able to induce DNA damage and a cytotoxic effect on PBMC. The TSP fraction was more cytotoxic than PM ₁₀ while the genotoxicity of both fractions was comparable. The genotoxic potential of the different samples was highly correlated to the amount of total PAH (correlation coefficient = 0.87), carcinogenic PAH (correlation coefficient = 0.88), B(a)P (correlation coefficient = 0.87) and to a less extend to the concentration of 1-nitropyrene (correlation coefficient = 0.66). The seasonal modulation suggests that in Rome the air is more toxic during winter, however in the warm season oxidized species including nitro-PAHs (evolving from secondary pollution) seem to balance the decrease of PAH concentration rates.     

Composite coatings based on linear and branched block copolymers for hydroxyapatite deposition in simulated body-fluid

ABSTRACT

In this work, the fabrication of composite coatings based on block copolymers and silicates deposited on stainless-steel plates through electrophoretic deposition technique was studied. Linear poly(?-caprolactone), and poly(dimethylsiloxane-block-ε-caprolactone) copolymers were obtained through ROP polymerization, whereas branched poly(hydroxyethyl methacrylate-co-(hydroxyethylmethacrylate-graft-ε-caprolactone)-block-ε-caprolactone) copolymers were synthesized by a one-pot technique by combining ROP and RAFT synthesis. SEM micrographs revealed homogenous and dense structures over the metallic substrate and the absence of micro-cracks. Thermal characterization revealed residual percentages of solids between 63% and 72% wt/wt. Finally, an in-vitro assessment confirmed the presence of a hydroxyapatite layer over coatings after immersion in a simulated body-fluid solution by XRD analyses.     

电纺丝法制备纳米纤维薄膜的降解性能研究

电纺丝法制备了PLLA、PLGA、PLLA/PLA-PEG、PLLA/HA纳米纤维薄膜,用SEM表征了纳米纤维的形貌.在37℃,pH值为7.4的PBS溶液中对4种纳米纤维薄膜的降解性能进行研究,通过GPC测试降解过程中聚合物分子量的变化,SEM表征降解过程中纳米纤维形貌的变化.结果表明:PLGA薄膜降解速率较快,吸水率最高;PLLA/PLA-PEG次之;PLLA降解速率较慢,吸水率最低,HA的加入可调节PLLA的降解速率.