p-(tricyanovinylidene)phenylhydrazones. Nucleophilic attack on carbon-carbon double bonds

The dispacement of a —CN group inp-(tricyanovinylidene)-phenylhydrazones, induced by amines, is investigated. The rate of the reaction is dependent on the polarity of the solvent and the observed second-order rate coefficientsk _obs ² for the —CN displacement increase with the amine concentration. A X-ray analysis of one of the substituted compounds is also reported.This work was supported by Ministero Pubblica Istruzione (Rome, 60%).     

Release of toluene from micron-sized, monodispersed, cross-linked, hollow polymer particles

The release behavior of toluene from the hollow-inside, micron-sized, monodispersed, cross-linked, polystyrene/polydivinylbenzene composite particles which had various cross-linking densities and shell thicknesses was examined. The hollow particles were produced by seeded polymerization utilizing the dynamic swelling method which we proposed in 1991. In comparison with that from hollow-free particles, there was a clear difference. The cross-linking density and shell thickness of the hollow composite particles did not affect the release rate in the former period, but did it in the latter one. Received: 2 February 2000/Accepted: 30 August 2000     

Kinetics of the solvolysis of chloropentacyanocobaltate(III) ions in water + 2-propanol mixtures

Rates of solvolysis of [Co(CN) ₅ Cl] ^3– have been determined in a range of water-rich water + 2-propanol mixtures over a range of temperatures and they show no simple correlation with dielectric constant. The variation of the enthalpy and entropy of activation with solvent composition show broad extrema and these are discussed in relation to the physical properties of the media. The application of a free energy cycle to the dissociative loss of the chloride ion in the transition state shows that the effect of changes in solvent structure as the alcohol content increases is to stabilize the emergent pentacyanocobaltate(III) ion Co(CN) ₅ ^2– relative to the chloropentacyanocobaltate(III) anion in the initial state.     

可降解聚合物药物膜的研究进展

综述了可生物降解聚合物药物膜的组成、制备方法及其药物释放行为的影响因素,为可生物降解聚合物药物膜的研究开发提供参考。     

PNIPA 类纳米水凝胶在药物缓控释研究中的应用

简要介绍了聚N-异丙基丙烯酰胺（Poly N-isopropylacrylamide,PNIPA）类纳米水凝胶的性质及智能响应机理,并重点综述了近年来此类纳米水凝胶在药物缓控释研究中的应用：作为脂溶性小分子药物的载体,达到增溶及缓控释药物的效果,并增强药物的稳定性及生物活性;作为水溶性小分子药物的载体,达到缓释该类药物的效果;作为生物大分子药物（蛋白,多糖）的载体,克服直接用药时的弊端;此外,还可作为基因工程载体。     

带有可调通道的嵌段共聚物胶束对药物的控制释放

用聚丙烯酸叔丁酯-b-聚乙二醇(PtBA45-b-PEG114)和聚丙烯酸叔丁酯-b-聚4-乙烯基吡啶(PtBA60-b-P4VP80)制备了复合胶束. 该胶束在pH=2.5的酸性水溶液中形成以PtBA为核, PEG和P4VP为壳的稳定球型结构. 在pH=12时, 壳层的P4VP链段变为疏水, 塌缩在PtBA的核上形成内壳, PEG链段继续保持溶解状态, 与成核的PtBA连接并穿过塌陷的P4VP内壳, 形成胶束的冠, 由于PEG处于溶解状态, 其分子链间有比较大的空隙, 可以控制一些小分子通过, 在胶束的表面形成通道. 该通道类似于生物膜的蛋白通道, 可以控制PtBA核与外界进行能量或物质交换的速度. 以布洛芬为模型分子, 负载在胶束内进行药物控制释放研究的结果表明, 胶束表面的通道可以起到明显控制布洛芬释放速度的作用, 并且药物的释放速度与通道在胶束表面的比例成正比.     

聚乳酸载药微球制备及释药性能研究最新进展

对可生物降解材料聚乳酸作为药物载体制备微球制剂的研究状况进行了综述。针对目前限制聚乳酸微球制剂临床应用存在的问题,重点介绍了降低药物突释,提高药物包封率,改善多肽和蛋白药物微球释药性能等方面研究的最新进展。聚乳酸载药微球在药物传输中有着广阔的研究和应用前景。     

蛋白质、多肽类药物控制释放体系的研究

近年来,蛋白质、多肽类药物广泛应用于各类疾病的治疗。本文对聚乙二醇修饰的蛋白质及蛋白质类药物控制释放这两大体系的研究进展做了较系统的总结和评述,并就更高级的靶向、易吸收的蛋白质药物体系的发展进行了展望。     

NIR触发的两亲性含糖聚合物修饰的纳米金棒的制备及应用

通过配体交换的方法成功将含糖聚合物PGAMA14-PCL32-SH接枝到纳米金棒的表面(Gly@Au NRs).借助X-射线光电子能谱(XPS)、动态光散射(DLS)、热重分析(TGA)等对Gly@Au NRs进行了表征.为了得到药物控释所需要的合适的实验条件,研究了近红外光照射下Gly@Au NRs在水溶液中的光热转换行为.用Gly@Au NRs包裹药物姜黄素(CUR),研究了药物的体外释放,发现近红外光能有效控制药物的体外释放.细胞实验结果表明含糖聚合物的接枝大大提高了纳米金棒的生物相容性.因此,Gly@Au NRs复合材料能够作为生物相容性载体材料,并实现近红外光触发的药物的可控释放.     

Synthesis and Characterization of Poly(Biphenyl‐2‐yl p‐Styrenesulphonate) as Profungicide in Controlled Release Technique

A new fungicide controlled release formulation was prepared by the reaction of p‐styrenesulphonyl chloride with biphenyl‐2‐ol (Dowicide A) as fungicide. The resulting monomer containing the fungicide was polymerized with benzoyl peroxide as initiator. The monomer and the polymer were identified by spectroscopic methods, and molecular weight of the polymer was determined by GPC. Also mp, Tg and Td of the polymer were identified by DSC. The release characteristic of the polymer was studied in neutral, alkaline, and acidic media. Also, the effect of the temperature on the release of bioactive agent (Dowicide A) was investigated. The hydrolysis data showed that the release rates are strongly dependent upon the pH of the medium and the temperature.     

Silylation of Cellulose with Hexamethyldisilazane in Ammonia – Activation, Catalysis, Mechanism, Properties

Synthesis of trimethylsilylcellulose (TMSC) from cellulose and hexamethyldisilazane (HMDS) in liquid ammonia is reviewed, with emphasis on the scope of the reaction and mechanistic features. Conditions for complete and for controlled stoichiometric partial silylation have been established. Stoichiometric desilylation of TMSC is also possible in tetrahydrofuran containing ammonia as hydrogen bond donor. The activating effect of ammonia, solubility of reactants, catalysis and kinetics of the heterogeneous reaction are discussed. Silylation follows first order kinetics in the presence of saccharin as the catalyst, indicating that the accessibility of hydroxy groups is not the rate-determining factor. TMSCs have a solubility window in THF with a DS from 1.6 to 2.6. This window is narrower for higher molecular weight TMSC.     

交联CMC控制释放除草剂的研究

本文报道以交联羧甲基纤维素囊化除草剂2，4，5－T、2，4－D和麦草畏二甲基胺盐所制成的控制释放体系的释放性能。研究了交联方法。制品形态、CMC取代度、交联剂用量和载药量等制备工艺条件对控释性能的影响。结果表明，以低取代度的CMC，经较大量甲醛交联制得的粒状制品，具有较好的控制释放性能。     

The influence of oxidative degradation on the preparation of chitosan nanoparticles

Chitosan nanoparticles were obtained via ionic crosslinking by using the sulfate ion. Chitosan molecular weight was varied by oxidative degradation of the chitosan β-glycoside bond, the molecular weight being indirectly monitored as the chitosan solution reduced viscosity at a fixed polymer concentration. The dependence between some physical properties of the resultant dispersions (turbidity, viscosity, zeta potential, and sedimentation column profile) and reduced viscosity was established. Atomic force microscopy images have shown the resultant particles formed to be clusters of chitosan nanoparticles with a diameter of ca. 70 nm, the interaction between these particles being characterized by FTIR spectroscopy as the result of sulfate bridging. At the end of the paper, the potential of these dispersions for the incorporation of anionic drugs via adsorption was evaluated using a model compound. The resultant dispersions were capable of adsorbing more than 25% of mass of chitosan, being the partition coefficient higher than 3,500.     

包膜控释肥及其膜材的研究进展

化肥在提高作物产量的同时也带来很多问题,由于作物对肥料的吸收是一个缓慢过程,大量的肥料不能及时被作物吸收而造成了环境污染,因此,有效提高传统化学肥料的利用率,能够减少对环境的污染。包膜控释肥在一定条件下能够实现对肥料养分释放速率的调控,显著提高肥料利用率,减少因肥料流失造成严重的环境污染。包膜控释肥的膜材是决定肥料控释性能的关键因素之一,本文对比分析了不同性质的膜材的优缺点及其对肥料控释性能的影响,解释了包膜控释肥养分释放机制,阐述了包膜肥在现实应用中存在的问题及对未来发展的展望。     

Protein Adsorption onto Nanosized Hydroxyapatite Particles for Controlled Drug Release

Nanosized hydroxyapatite(nsHAp) was synthesized to examine its possibility as a controlled release carrier of protein. To achieve effective protein release from nanosized hydroxyapatite, the study of the adsorptive properties of protein on nsHAp and different influence parameters such as pH, calcium, and phosphate concentrations during the adsorption process is necessary. Ovalbumin(OVA) was selected as the model of growth factors. The results show that the amount of OVA adsorbed onto nsHAp in acetic buffer(pH=3.6) is more than that in acetic buffer(pH=5.6) because of the electric interaction. The amount of OVA adsorption in phosphate buffer solution(PBS) is smaller than that in acetic buffer because of surface complexation and surface hydroxylation. The presence of Ca2 dramatically increases the adsorbed amount of OVA in acetic buffer on maintaining the same pH. Meanwhile, the release kinetics of OVA adsorbed onto nsHAp(nsHAp-OVA) was also examined. The amount of released OVA in PBS(pH=5.6) was significantly smaller than that released in solution of pH=7.0. All the results suggest that nanosized hydroxyapatite particles could be successfully used as controlled released carrier of protein.     

Preparation and drug release behavior of temperature-responsive mesoporous carbons

A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery.     

高分子免疫佐剂

随着新一代疫苗的发展,安全、高效的免疫佐剂的研究日益紧迫。本文介绍了这一领域的研究,扼要综述了高分子免疫佐剂的研究进展,并展望了高分子免疫佐剂的发展前景。     

CS-PMA30水凝胶对考马斯亮蓝控释性能的研究

壳聚糖(CS)是自然界中唯一的聚阳离子碱性多糖,具有良好的组织相容性、生物可降解性、无毒、无刺激、pH响应性等优点,因而在药物控释领域的具有潜在的应用价值。将聚阳离子壳聚糖与聚阴离子甲基丙烯酰氧乙基磷酰胆碱-甲基丙烯酸二元共聚物(poly(MPC-co-MA), PMA30)进行静电复合,制备CS-PMA30聚离子水凝胶。以考马斯亮蓝为模型药物,对CS-PMA30水凝胶的控释性能进行研究。结果表明,该CS-PMA30体系是通过静电作用形成的物理交联水凝胶,具有pH响应性,有望在药物控释、组织工程等领域得到广泛应用。     

淀粉囊化农药控释缓释技术

介绍了近20年来淀粉囊化农药控释缓释技术的研究和发展概况,详细综述和讨论了淀粉囊化技术的囊化方法、影响释放特性的主要因素、制品耐水性问题的解决办法、开发应用研究及发展前景。