Preparation of mesoporous silica nanoparticle with tunable pore diameters for encapsulating and slowly releasing eugenol

Fragrances are frequently added to a variety of products, including food, cosmetics and health products. However, the high volatility and instability of essence limit its application in some fields. In this study, mesoporous silica nanoparticles (MSNs) were prepared to encapsulate eugenol, which could reduce the volatilization of the fragrance molecules. A facile approach was presented to synthesize MSNs with three different pore diameters for encapsulating eugenol. In addition, the properties of MSNs including mean particle size, morphology, encapsulating efficiency and release tendency were characterized. Results showed that the larger the pore diameters of MSNs, the more aromatic molecules were adsorbed. Furthermore, the release mechanism was described as the smaller the pore diameters of MSNs, the slower the release of eugenol.     

Fabrication of ultrathin polyelectrolyte fibers and their controlled release properties

Ultrathin fibers comprising 2-weak polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) were fabricated using the electrospinning technique. Methylene blue (MB) was used as a model drug to evaluate the potential application of the fibers for drug delivery. The release of MB was controlled in a nonbuffered medium by changing the pH of the solution. The sustained release of MB in a phosphate buffered saline (PBS) solution was achieved by constructing perfluorosilane networks on the fiber surfaces as capping layers. Temperature controlled release of MB was obtained by depositing temperature sensitive PAA/poly(N-isopropylacrylamide) (PNIPAAM) multilayers onto the fiber surfaces. The controlled release of drugs from electrospun fibers have potential applications as drug carriers in biomedical science.     

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。     

Fliposomes: new amphiphiles based on trans-3,4-bis(acyloxy)-piperidine able to perform a pH-triggered conformational flip and cause an instant cargo release from liposomes

Amphiphilic trans-3,4-bis(acyloxy)-1-benzylpiperidines able to perform a pH-triggered conformational flip (flipids) have been suggested as components of a new type of pH-sensitive liposomes (fliposomes). According to ¹H NMR, their acid-induced conformational flip occurs in methanol-d₄ when the apparent pD decreases from 6 to 3. The protonation-generated intramolecular hydrogen bond and electrostatic interactions make the conformer with axial acyloxy-groups predominant, which drastically increases the separation of hydrocarbon chains. The power of this trigger was estimated as ?10 kJ/mol. This flip perturbs the liposome membrane causing rapid release of the liposome cargo specifically in response to lowered pH. The pH-sensitive fliposomes containing one of these flipids, POPC and PEG-ceramide, and loaded with ANTS/DPX performed a content release within a few seconds at pH <5 demonstrating a potential of the piperidine derivatives as pH-switches for the design of liposomes for drug/gene delivery.     

包膜型多功能缓/控释肥料的研究现状及进展

缓/控释肥料能够在保证粮食产量的前提下,提高养分利用率,减少肥料养分流失对环境造成的危害。包膜型缓/控释肥料对养分具有更好的控释效果,通过包膜材料的组成设计,最有可能实现养分的释放速率与作物的需肥规律相匹配。本文综述了包膜型缓/控释肥料的国内外研究现状,肥料养分的控释机理和释放性能评价方法,阐述了包膜型缓/控释肥料研究和应用中存在的问题及未来的发展趋势。     

Controlled release of atenolol from freeze/thawed poly(vinyl alcohol) hydrogel

Physically crosslinked polymeric films containing atenolol drug were formulated and the release of the drug was evaluated with view to investigate the feasibility of these films as drug delivery systems. Freezing and thawing process for PVA was used to prepare a controlled release device for atenolol drug. The process included incorporation of the drug into PVA film during the freezing and thawing process. The PVA has used a molecular weight of 125 k and degree of saponification of 98. Various amounts of the atenolol drug were incorporated into the freeze/thawed PVA. The in vitro release behavior of atenolol from these films was investigated. The drug release profiles from the polymeric formulations indicated initial high rate of release followed by slow rate of the release. The release of atenolol increased with increasing drug concentration in the film. The results showed the feasibility of the use of freezing and thawing technique to control the release of atenolol drug from PVA.     

Cationic liposomes modified with non-ionic surfactants as effective non-viral carrier for gene transfer

A defined change in formulation components affects the physical and chemical characteristics of cationic liposomes (CLs) carriers in many ways. Therefore, a great degree of control can be exercised over the structure by modifying the CLs with various materials, leading to new innovations for carrier improvement. In the present study, surface modifications of cationic liposomes with non-ionic surfactants—sorbitan monoesters serials (Span 85, 80, 40 and 20) were carried out for developing a new gene transfer carrier. Span modified cationic liposomes (Sp-CLs) were prepared by reverse phase evaporation method (RPV) and self-assemble complexes of antisense oligonucleotides/surfactant modifying cationic liposomes were prepared by auto-coacervation through electrostatic effect. Characterization of Sp-CLs and the self-assembled complex was performed by electron microscope, particle size, zeta potential, turbidity and agarose electrophoresis. Furthermore, in vitro cellular uptake experiment showed that Span plays a role in enhancing the cellular uptake of encapsulated oligonucleotides mediated by Sp-CLs by the endocytosis-dependent route. CLs modified with Span 40 significantly facilitated the cellular uptake by COS-7 cells and HeLa cells; also showed some positive effect on gene expression. That suggests it is a potential non-viral carrier for efficient gene transfer.     

Immobilization of cationic rifampicin-loaded liposomes on polystyrene for drug-delivery applications

Polymer-associated infections are a major problem in implanted or intravascular devices. Among others, microorganisms of the staphylococcal family have been identified as the most important culprit. Prevention of bacterial adhesion and colonization of polymeric surfaces by release of antimicrobial agents incorporated into the polymers itself are currently under study. We have developed a novel method for the functionalization of a polymeric surface which is based on the deposition of covalently coupled lipid structures from antibiotic loaded vesicles. We have found that such process significantly reduces the bacterial growth on polystyrene material. In this work, lipid coverage obtained from multilamellar (MLVs) and extruded unilamellar (LUVs) vesicles were analyzed with respect to their adhesion efficiency on three types of polystyrene (PS) well-plates. Two methods of lipid deposition were characterized and compared in terms of surface lipid density and time stability: deposition of cationic vesicles on negatively charged surfaces and formation of covalent linkages between functionalized lipids and amines enriched surfaces. In order to study the antibiotic encapsulation efficiency we measured how the rifampicin (RIF) loading was affected by changes of liposome charge upon introduction of various amounts of stearylamine (SA), distearoyl-trimethylammonium propane (DSTAP) or dioleoyloxypropyl-trimethylammonium chloride (DOTAP) into the liposomal formulation. RIF-coated polymeric surfaces were also tested against a Staphylococcus epidermidis strain to evaluate their efficacy in vitro, showing that only approximately 2% of such bacteria inoculated on MLV-treated PS substrate were able to proliferate. Covalently immobilized lipid films showed about a tenfold increase in time stability compared to electrostatically bonded lipid films. Furthermore, substrates covalently modified with RIF-loaded MLVs retained an antibacterial activity for up to 12 days when aged in buffer at 37 degrees C. Such antimicrobial polymer coatings show promise for their use as antibacterial barrier for the prevention of catheter-related infections.     

交联淀粉囊材对含羧基类除草剂的缓释性能研究

以淀粉或变性淀粉为囊材,对囊化农药进行控释或缓释,可延长药效、避免药害、减少浪费和防止污染^[1-4]。 然而,水溶胀程度大导致淀粉胶囊制品耐水性差。目前,降低其水溶胀程度的措施有淀粉黄原酸酯化后的交联囊化法^[5]、淀粉－钙加合物法^[6]和淀粉－硼酸络合物法^[7,8]。但由于含羧基类农药的水溶性对碱敏感,上述方法中淀粉的糊化、化学改性和交联所必须的强碱性条件会使含羰基类农药呈现水溶性,致使它们在水环境条件下会以更大的速度从淀粉囊材中释放出来。可 见,含羧基类农药不能用这几种方法来改善其缓释性能。本文以甲醛为交联剂,在淀粉囊化农药过程中对淀粉囊材进行交联,能够有效地降低淀粉胶囊制品的水溶胀程度的和所囊药剂的释放速度,延长有效控释时间,较大幅度地提高其缓释性能和耐水性。该囊化方法解决了一些碱敏感性农药在淀粉中的囊化问题。     

含有偶氮苯基的水溶性共聚物包覆的脂质体的光控释放行为

为了研究侧链含有偶氮苯基的水溶性共聚物的光异构化对脂质体内包容物的光控释放的影响,设计合成了N-异丙基丙烯酰胺(NIPAM)和丙烯酰胺基偶氮苯(AAAB)的共聚物。以5(6)-羧基荧光素(5(6)-CF)为水溶性标记物,研究了共聚物包覆的小单层脂质体(small unilamellar vesicles,SUV)在室温25℃时的释放行为。研究发现,在波长大于350nm的光源照射下,共聚物包覆的脂质体中5(6)-CF的释放速率明显提高,证明侧链含有偶氮苯基的水溶性共聚物包覆的脂质体具有明显的光控释放性能。并对此现象作了讨论。     

烯烃可控/活性正离子聚合新方法与新工艺及其应用

正离子聚合是高分子科学中重要的聚合方法之一,也是制备聚异丁烯或丁基橡胶等关键材料不可或缺的聚合方法.本文总结了异丁烯、苯乙烯及其衍生物等单体可控/活性正离子聚合的新引发体系、聚合反应特征的调节与转化、水相介质中正离子聚合新方法与新工艺、微观分子混合与正离子聚合新工艺及其用于设计合成异丁烯基聚合物.这些方法与技术是发展高效节能与绿色减排先进聚合物生产技术的重要途径,部分研究成果已在产业化中得到应用与验证.发展可控/活性正离子聚合新体系、新方法与新工艺,为实现绿色低碳高分子化工过程及相关产品工程（新结构、新功能、高性能与高品质）提供了新思路与新技术.     

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。     

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。     

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。