毒死蜱/壳聚糖改性凹凸棒土/海藻酸钠微球的制备与缓释性能

采用接枝方法制备了壳聚糖改性凹凸棒土,利用外源挤出法制备了毒死蜱/壳聚糖改性凹凸棒土/海藻酸钠复合微球,利用红外、热重分析和X射线衍射对改性凹凸棒土的结构进行了表征,并研究了改性凹凸棒土对载药微球的载药率、包封率、溶胀性能及缓释性能的影响。结果表明,毒死蜱仍以结晶态存在于复合微球中;壳聚糖改性凹凸棒土复合微球的载药量和包封率均高于相应的酸化凹凸棒土复合微球;加入凹凸棒土降低了载药微球的溶胀率、提高了微球的缓释性能,且壳聚糖改性凹凸棒土在抑制微球溶胀和增强缓释方面优于酸化凹凸棒土;载药微球的释药行为可用HIGUCHI动力学模型来描述。     

壳聚糖缓释微球的制备与表征

以壳聚糖(Chitosan)、戊二醛(Glutaraldehyde)、尿素(Urea)为主要原料,采用乳化-化学交联法制备尿素-壳聚糖缓释微球.通过红外光谱测试,分析缓释微球的结构特征;通过扫描电镜测试,观察微球的微观形貌;通过交联度测试确定戊二醛的最佳用量;通过缓释测试,测定壳聚糖微球的缓释效果.结果表明:采用乳化-...     

戊二醛与甲醛交联壳聚糖微球的比较研究

壳聚糖微球是肥料和农药的重要缓释载体之一。根据相关实验数据及文献显示,纯的壳聚糖成球性能差,易溶解,需要加入一定的交联剂、乳化剂和致孔剂对其进行交联改性,改善微球的性能。分别采用戊二醛、甲醛两种交联剂,通过乳化-化学交联方法制备壳聚糖微球。通过扫描电子显微镜对壳聚糖微球表面、内部结构及形态特征进行观察,测量壳聚糖微球粒径的大小。采用红外光谱(FT-IR)以及交联度测试对两种交联微球进行了对比。结果表明:以戊二醛为交联剂所制得的壳聚糖微球各个方面性能均优于以甲醛为交联剂所制得的壳聚糖微球。     

不同交联方法制备的人表皮生长因子凝胶微球的性能比较

目的比较不同交联方法制备的人表皮生长因子(Humanepid ermal growth factor,hEGF)凝胶微球的体外性能。方法采用化学交联、光交联和热交联方法,制备复合hEGF凝胶微球,观察其形态,测定其粒径、质量残留率、载药率和包裹率,并采用ELISA法检测hEGF的体外释放效果。结果 3种方法制备的凝胶微球的形态、粒径、载药率和包裹率均无显著差异;但化学交联法制备的微球释药时间明显较光交联和热交联法制备的微球长,降解速度较光交联和热交联法制备的微球慢。结论化学交联法制备的hEGF凝胶微球性能好,具有作为缓释生长因子载体的应用前景。     

白炭黑对阿维菌素/海藻酸钠/壳聚糖复合微球性能的影响

为了研究白炭黑对阿维菌素/海藻酸钠/壳聚糖复合微球的性能影响,以阿维菌素为模型药物,海藻酸钠和壳聚糖为包埋材料,白炭黑为结构性能改良剂,采用挤出外源凝胶法和复凝聚法制备负载阿维菌素的复合微球,并对微球溶胀性、药物溶出性能进行了表征。结果表明,所制备的微球具有温度和p H值敏感性,添加白炭黑可以抑制复合微球溶胀性,并能改善阿维菌素的缓释性能。     

白炭黑对阿维菌素/海藻酸钠/壳聚糖复合微球性能的影响

为了研究白炭黑对阿维菌素/海藻酸钠/壳聚糖复合微球的性能影响,以阿维菌素为模型药物,海藻酸钠和壳聚糖为包埋材料,白炭黑为结构性能改良剂,采用挤出外源凝胶法和复凝聚法制备负载阿维菌素的复合微球,并对微球溶胀性、药物溶出性能进行了表征。结果表明,所制备的微球具有温度和p H值敏感性,添加白炭黑可以抑制复合微球溶胀性,并能改善阿维菌素的缓释性能。     

具有光催化活性P（AM-AA）/CdS/TiO2复合微球的制备研究

以反相悬浮聚合法合成的P(AM-AA)微凝胶为模板,采用外源沉积法制备了P(AM-AA)/CdS复合微球,以TBOT为前驱体,通过溶胶-凝胶法制备具有光催化活性的P(AM-AA)/CdS/TiO2复合微球。结果表明,复合微球兼具有微凝胶的固有优点以及CdS和TiO2的光学性质,为进一步研究光解水制氢提供依据。     

壳聚糖-海藻酸钠载药微球的缓释性能研究

采用乳化交联法制备出负载5-氟尿嘧啶(5-Fu)的壳聚糖-海藻酸钠磁性载药微球。利用红外(FIRT)、X射线衍射(XRD)、热重(TG)、紫外-可见分光光度计(UV)对1其进行结构表征和缓释性能研究,考察了不同因素对载药微球缓释性能的影响。结果表明,油水相体积比为1∶1时载药性能最佳,载药量为6.69%,包封率为22.00%,产物发生交联反应且保持原有晶型,同时在不同p H值环境下载药微球相对5-Fu药物有明显的缓释作用,并且在p H=8.4时药物达到最大释放量,微球适用于给肠癌细胞靶向供药。     

壳聚糖微球及壳聚糖-明胶复合物微球的制备及缓释性能研究

采用乳化-化学交联法制备壳聚糖微球及壳聚糖-明胶复合物微球,并通过实验确定了最佳的成球条件:即m(壳聚糖)∶m(明胶)=2∶1 span-80用量为10g/100 mL,乳化剪切速度为600 r/min,交联率为60％,固化时间为40min.该方法制备的壳聚糖微球球形圆滑,粘连度小,亲水性好.此外在对壳聚糖药物缓释的研究基础上,对壳聚糖复合明胶后,对药物缓释的影响情况进行了研究探索.以生物可降解性和生物相容性好的壳聚糖和明胶为载体承载阿司匹林,研制出阿司匹林壳聚糖-明胶微球,为阿司匹林提供了一种理想的缓释载体.     

改性纤维素微球的制备及其药物缓释性能研究

将微晶纤维素(MCC)溶于1-烯丙基-3-甲基氯代咪唑(AmimCl)离子液体中,使用4-二甲氨基吡啶(DMAP)作为催化剂,采用开环聚合的方法,成功合成了纤维素接枝L-聚乳酸(Cellulose-g-PLLA),并采用乳化-溶剂挥发法成功制备了纤维素微球。通过核磁共振(HNMR)、透射电子显微镜(TEM)等对聚合物进行表征。对微球的降解性、缓释性及缓释动力学进行了探讨。结果表明,Cellulose-g-PLLA微球具有作为缓释药物载体的能力。     

快速膜乳化与热固化法制备粒径均一的pH敏感壳聚糖季铵盐凝胶微球

以具有升温自固化特性的壳聚糖季铵盐/甘油磷酸钠混合溶液为水相,利用快速膜乳化与热固化法制备了粒径均一、pH敏感的壳聚糖季铵盐凝胶微球,考察了跨膜压力、水油相组成、水油相体积比及微孔膜孔径等对微球粒径、结构和药物包埋率的影响. 结果表明,得到粒径698±57.33, 1145±71.48, 2021±53.63及3984±191.72 nm、粒径分布窄(多分散系数<0.1)、药物包埋率高达75.49%±2.62%的凝胶微球. 所制微球生物相容性好,有明显的pH敏感性,中性和碱性环境下结构稳定,药物缓释,pH=7.4时24 h内药物累计释放率为34.6%;酸性环境下微球崩解,药物快速释放,pH=5.5时1 h内药物累计释放率高达79.6%.     

An improvement of microfluidic-assisted internal gelation in the preparation of millimeter-sized ceramic microspheres

The microspheres prepared by the microfluidic-assisted internal gelation process are still challenging to reach the millimeter size due to the large gravity. The gravity would affect the sphericity and size uniformity of microspheres. The improved microfluidic-assisted internal gelation process is designed and optimized to produce large-sized monodisperse ceramic microspheres with good sphericity. The movement mechanism of millimeter-sized sol droplets and gel microspheres in the microchannel is summarized and the state of the dispersed phase entering the measuring cylinder is controlled. The friction between the gel microspheres and the tubing wall is reduced as much as possible, and ZrO₂ ceramic microspheres of 500 ± 5 μm with good sphericity are prepared with the broth at room temperature. The mechanism of sol droplets entering the oil surface is explored to demonstrate the superiority of the improved microfluidic-assisted internal gelation process. The improved microfluidic-assisted internal gelation process could be directly extended to preparing other millimeter-sized monodisperse ceramic microspheres.     

聚氨酯微球的合成及其表征

采用反相悬浮聚合法，以甲苯二异氰酸酯、聚醚及三乙醇胺为原料，进行缩聚交联反应，合成了聚氨酯弹性体微球。用扫描电子显微镜等方法表征了微球的形态及溶胀性能，通过BET法测定了微球的比表面积。并通过微球对模型药物异烟肼的释放实验，讨论了微球的化学组成对药物释放性能的影响。     

Physical,structural, and mechanical characterization of calcium–shellac microspheres as a carrier of carbamide peroxide

Calcium–shellac microspheres with encapsulated carbamide peroxide (CP) were made by emulsification to generate an emulsion including shellac ammonium salt aqueous solution with soluble CP dispersed in sunflower oil with calcium chloride powders, followed by gelation between shellac and calcium. The effects of formulation and processing conditions on the encapsulation efficiency of CP, the physical, structural, and mechanical properties of calcium–shellac microspheres, including size, inner structure, and mechanical strength, were investigated. The sizes of the prepared microspheres were in the range of 10–100 μm, depending on the agitation speed used in the emulsification process. The morphology of calcium–shellac microspheres was characterized using scanning electron microscopy and image analysis. Their inner structure was evaluated using X‐ray microcomputed tomography, and their mechanical strength was determined by a micromanipulation technique. The structure and mechanical strength of the microspheres were compared with those bigger calcium–shellac beads (1–3 mm in diameter) made by extrusion followed by gelation (Xue and Zhang, J Microencapsul 2008, 25, 523), and clear contrast in the properties between the two preparation methods has been found. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

羧甲基壳聚糖-蓖麻油基聚氨酯农药缓释微球的制备及性能

以羧甲基壳聚糖（CMCS）、蓖麻油（CO）和异佛尔酮二异氰酸酯（IPDI）为原料，自乳化法制备了羧甲基壳聚糖-蓖麻油基聚氨酯微球（CO-CMCS-PU），通过分子自组装法负载阿维菌素（AVM）得到载药微球（CO-CMCS-PU@AVM）。采用FTIR、1HNMR、SEM、TGA等对产品结构及形貌进行表征，并探究了不同药量载药微球的包封率、缓释性能、抗紫外性能、叶面接触角和黏附性能。结果表明，相比AVM分散液，紫外照射后载药微球中AVM的保留率提高到43%，说明CO-CMCS-PU载体的抗紫外性能良好；载药微球比AVM分散液在黄瓜叶面上的接触角降低了20%以上，滞留量提高了40%以上，说明其在叶面上有较好的黏附性和润湿性；载药微球包封率可达80%以上，具有良好的缓释和pH响应释放性能，释药行为符合First-order动力学模型，药物释放受Fickian扩散控制。     

Microfluidic fabrication of ZrO2 microspheres using improved external gelation aided by polyacrylamide networks

Microfluidic generation of emulsion microdroplets, combined with external gelation, is a promising method for the continuous production of high-quality ceramic microspheres. However, the external gelation mode is sensitive to the environmental concentration of sol-gel triggering agent, resulting in gel deformation due to uneven infiltration and reaction within the sol microdroplets. In this work, a polyacrylamide (PAM) gel network was used to prevent the microdroplets from undergoing apparent deformation throughout the gelation process, and dense ZrO₂ microspheres with high monodispersity and sphericity were fabricated successfully. Importantly, owing to the assistance of PAM network, the external gelation process becomes less sensitive and can be treated with a substantially higher triggering agent concentration, thus allowing a faster and more efficient sol-gel production of ZrO₂ ceramic microspheres.     

Preparation of monodisperse YSZ ceramic microspheres by high-throughput and instant-mixing droplet microfluidic system

The internal gelation process without cooling at room temperature is a significant challenge for the preparation of yttria-stabilized zirconia (YSZ) ceramic microspheres. In this work, a high-throughput and instant-mixing droplet microfluidic system that can prepare monodisperse YSZ ceramic microspheres was constructed. It mixed two stable solutions at room temperature in an active micromixer at a flow rate of mL/min, and then the mixed unstable precursor solution was quickly dispersed into sol droplets through a coaxial microfluidic device, and the droplets solidified into gel microspheres. The washed and dried gel microspheres could be sintered to obtain ceramic microspheres. Compared with no-micromixing and T-junction micromixers, the system had the best mixing performance and Y and Zr elements in the prepared ceramic microspheres were evenly distributed. Therefore, the system overcame the problem of precursor solution solidification and clogging of the device, and provided a new approach for the internal gelation process without cooling at room temperature.     

The Fabrication of ZrO2–ZrC Microspheres by Internal Gelation and Carbothermal Reduction Process

ZrO₂–ZrC (ZrCO) ceramic microspheres were fabricated by combination of internal gelation and carbothermal reduction process. The internal gelation broth containing carbon powders was prepared and stored at room temperature of 25°C to form a precursor of microspheres. By dropping droplets of the broth into hot silicone, the gel microspheres would solidify within a few seconds by decomposition of hexamethylenetetramine (HMTA). The dispersability of the carbon powders in the broth is the key factor to producing ZrCO microspheres with uniform density distribution, as zirconium carbides are generated by the direct reduction of ZrO₂ with carbon. The ZrCO ceramic microspheres fabricated with various mass ratio of ZrO₂ and ZrC have good sphericity and no cracks through optimizing washing and heat treatment process.     

Heterogeneous styrene–divinylbenzene copolymers in collapsed and reexpanded states

The pore structure of styrene–divinylbenzene (DVB) copolymers formed by phase separation before or after gelation was compared using apparent densities and mercury porosimetry. The copolymers were prepared with di-2-ethylhexyl phthalate (DOP) as diluent. The pore structure of copolymers formed in homogeneous gelation can collapse upon drying in the rubbery state. The collapsed pores have a mean diameter of about 100–200 Å corresponding to the interstices between the microspheres. The collapsed microspheres reexpand again during the sulfonation or chloromethylation reactions, or during the solvent exchange. The pore structure of styrene–DVB networks formed in heterogeneous gelation do not collapse on drying in the swollen state, this being a stable and permanent porosity. The critical crosslink density for transition from homogeneous to the heterogeneous gelation represents a borderline between stable and unstable porosity. The drastical change of swelling and porosity values at the critical crosslink density is due to the collapse of unstable pores.     

双乳化-凝胶法制备单分散海藻酸钙微球及其载BSA研究

采用双乳化-凝胶法制备了单分散的海藻酸钙凝胶微球,并通过正交试验系统考察了海藻酸钠浓度、氯化钙浓度、表面活性剂浓度、搅拌速度和油水比对海藻酸钙凝胶微球粒径及形貌的影响。在优化的条件下,制备出了平均粒径为4μm、单分散和球形度好的海藻酸钙凝胶微球。包埋模型药物牛血清白蛋白(BSA)的过程中,以去离子水作为洗涤液洗涤海藻酸钙微球时,BSA的包封率仅为13%左右;当水洗液的pH值为3.2时,BSA的包封率提高到66%左右,载药率可达16%,这是海藻酸钙pH值响应溶胀和BSA与海藻酸盐之间静电作用的结果。微球中BSA的体外释放曲线表明,该系统具有在模拟胃液中释药速率慢、释药量低、模拟肠液中释药迅速的特性。因此,双乳化-凝胶法制备海藻酸钙微球有望成为制备蛋白类药物控释制剂的一种新方法,以达到靶向快速给药的目的。