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。     

4A沸石对海藻酸钠壳聚糖复合微球性能的影响

以壳聚糖和海藻酸钠为原料，4A沸石为结构改良剂，采用复凝聚法制备4A沸石/海藻酸钠/壳聚糖复合微球，利用显微镜、扫描电镜、红外光谱和X射线衍射等对复合微球进行了表征，并考察了4A沸石对复合微球成球性能和溶胀性能的影响。结果表明，随着4A沸石添加量的增加复合微球的质量和粒径也增大，添加4A沸石有利于复合微球成球，成球率最高达到98.5%，且冷冻干燥后粒径均匀、球形规则。在不同pH和温度条件下，4A沸石对复合微球能有效抑制微球的大量溶胀，同时保持良好的pH和温度敏感性。4A沸石可以作为药物控释体系中的结构改良剂进一步研究应用。     

凹凸棒黏土对壳聚糖/海藻酸钠微球释放性能的影响

将凹凸棒黏土(ATP)与海藻酸钠(SA)进行复合以改善SA的缓释性能。以ATP/SA复合物为球芯材料,壳聚糖(CS)为包覆材料,采用复凝聚法制备凹土/海藻酸钠/壳聚糖复合微球(ASCM),并以双氯芬酸钠(DS)为模型药物,考察了凹土添加量对复合微球溶胀性能、载药性能和缓释性能的影响。结果表明,凹土的加入改善了微球的溶胀性能和缓释性能,而对微球载药性能影响不大。与海藻酸钠/壳聚糖微球(SCM)相比,当复合微球中ATP/SA(w/w)为20%时,其在pH6.8的磷酸缓冲溶液中2 h的累积释放率由58.8%减小到38.7%。复合微球体外释放动力学数据表明,其释药行为可以很好地用一级动力学方程拟合。凹土的加入有效改善了SA的缓释性能,ASCM可作为缓释药物的载体材料。     

壳聚糖-纳米二氧化钛微球处理染料废水的研究

以壳聚糖-纳米二氧化钛微球为絮凝剂处理染料废水,研究了其对染料废水的脱色性能和COD的去除率。初步考察了pH值、壳聚糖-纳米二氧化钛微球对脱色效果的影响,比较了壳聚糖与壳聚糖-二氧化钛微球处理艳蓝染料废水的数据,壳聚糖-纳米TiO2的脱色效果和COD的去除率明显优于壳聚糖,实验结果表明用壳聚糖-纳米TiO2是处理难降解染料废水的有效方法。     

羧化改性壳聚糖微球的制备及吸附硝基酚的性能

采用反相悬浮环氧氯丙烷交联、氯乙酸羧甲基化制备交联羧化壳聚糖微球,用红外光谱和扫描电镜对微球进行表征,并用于2,4-二硝基苯酚的吸附研究。考察了吸附时间、溶液pH值、酚的浓度和NaCl等因素对2,4-二硝基苯酚吸附的影响。结果表明,羧化改性交联壳聚糖微球具有较好的耐酸碱性能,对2,4-二硝基苯酚有良好的吸附性能,在pH值为3.6条件下,吸附在瞬间就能达到平衡,吸附量达230 mg.g-1,吸附符合Freundlich等温方程。     

4A沸石对海藻酸钠/壳聚糖微球性能的影响

以壳聚糖和海藻酸钠为载体、4A沸石为性能改良剂,采用锐孔法制备了4A沸石/海藻酸钠/壳聚糖复合微球,利用显微镜、SEM、FTIR和XRD对复合微球进行了表征,考察了4A沸石对复合微球成球率和溶胀性能的影响。结果表明:随着4A沸石添加量的增加,复合微球的质量和粒径均增大,添加4A沸石有利于复合微球成球,成球率最高为98.5%(添加4A沸石1 g),且冷冻干燥后微球具有均匀的粒径和规则的球形形状。在不同pH(3、5、7)和温度下,4A沸石能有效抑制微球的过度溶胀,但仍然保持良好的pH和温度敏感性。     

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.     

羧甲基壳聚糖离子配位微球的制备及性能研究

以羧甲基壳聚糖(CMCHS)为主要原料,采用静电脉冲液滴发生器制备羧甲基壳聚糖离子配位微球。光学显微镜观察微球具备规整形貌,扫描电镜分析显示干球粒径约为100μm且表面呈多孔结构;红外光谱证明其内部具有由CMCHS上的羧酸根与Ca^2 配位形成的羧酸盐结构。溶胀实验表明,CMCHS溶液浓度、金属离子种类及其浓度等制备条件均影响微球的溶胀性能．且其溶胀行为对pH值较敏感。药物体外释放初步研究表明,CaCl2浓度和释放介质pH值均对微球的释放性能产生影响。研究对其进一步应用于药物释放等领域具有重要意义。     

α-酮戊二酸修饰壳聚糖微球对牛血清蛋白的吸附

采用反相悬浮法制备交联壳聚糖微球,再与α-酮戊二酸反应生成Schiff碱,NaBH4还原制得改性壳聚糖微球.用FFIR、SEM和XRD对其进行表征,并将之用于牛血清白蛋白的吸附研究,考察了吸附时间,溶液pH值、牛血清白蛋白的浓度.温度、NaCl含量等因素对牛血清白蛋白吸附的影响.结果表明,α-酮戊二酸改性交联壳聚糖微球不溶于酸和碱,对牛血清白蛋白具有良好的吸附性能,在pH=5.0时,吸附在1 h内可达平衡,吸附数据符合Langmuir等温方程和Lagergren二级动力学方程.     

阿司匹林-壳聚糖缓释微球的制备和释药性能研究

采用乳化交联法制备阿司匹林-壳聚糖缓释凝胶微球,通过透析实验检测微球的体外释放特性。应用正交实验设计,考察了壳聚糖浓度,搅拌速度,阿司匹林/壳聚糖质量比,交联时间对微球制备的影响。体外释放实验表明,壳聚糖微球前5个小时的释放符合SRP的释药行为。以5个小时的体外释放总量为指标进行直观分析,交联时间对5小时的体外释放总量影响最大。     

Drug Release Kinetics of Spray-Dried Chitosan Microspheres

The aim of this article was to investigate the drug release kinetics of spray-dried chitosan microspheres using various kinetic models. The mean particle size and encapsulation efficiency of cross-linked chitosan microspheres was between 3.8 and 4.2 μm and 96.3 and 98.7%, respectively. Spray-dried chitosan microspheres were spherical in shape with smooth surface. The surface morphology of spray-dried chitosan microspheres was affected by the crystallinity of the loaded drug and cross-linking agent. The release data of the spray-dried chitosan microspheres were treated with zero-order, first-order, Higuchi, Korsmeyer, and Kopcha kinetic models and best fit was observed with Higuchi model, indicating the release of drug from spray-dried chitosan microspheres followed Fick's law of diffusion.     

Drug Release Kinetics of Spray-Dried Chitosan Microspheres

The aim of this article was to investigate the drug release kinetics of spray-dried chitosan microspheres using various kinetic models. The mean particle size and encapsulation efficiency of cross-linked chitosan microspheres was between 3.8 and 4.2 μm and 96.3 and 98.7%, respectively. Spray-dried chitosan microspheres were spherical in shape with smooth surface. The surface morphology of spray-dried chitosan microspheres was affected by the crystallinity of the loaded drug and cross-linking agent. The release data of the spray-dried chitosan microspheres were treated with zero-order, first-order, Higuchi, Korsmeyer, and Kopcha kinetic models and best fit was observed with Higuchi model, indicating the release of drug from spray-dried chitosan microspheres followed Fick's law of diffusion.     

交联壳聚糖磁性微球制备及吸附性能研究

采用超声波辅助化学共沉淀法制备纳米Fe3O4,在此基础上选用乳化交联法,以戊二醛为交联剂,壳聚糖为单体包埋磁性纳米颗粒,合成了微米及纳米尺度上具有高吸附性、介质分离的磁性壳聚糖纳米微球(MCTS),并对复合材料的吸附性能进行了讨论。通过将壳聚糖包裹纳米磁性粒子制备成的磁性壳聚糖微球,具有比表面积大、多孔、易回收、可再生等优点,并且该磁性微球稳定性好、吸附性能强,有效地提高了壳聚糖的应用价值,而对于金属废水处理、药物的分离纯化和天然药物有效成分的富集纯化等意义重大。     

Investigation on Conjugation Capacity of New Chitosan Carriers Based on Conjugated Model Toward Enzyme Delivery

In this work, for the first time, the authors report their observations on cross-linking condition, and its effects on conjugation capacity of a bioactive model. Therefore, carriers of chitosan films and microspheres were produced by using glutaraldehyde as bifunctional cross-linking agent. The following stages were carried out: preparation of cross-linked chitosan films and microspheres, conjugation of drug model on films and microspheres, investigation on the properties of the synthesized carriers and finally enzyme immobilization studies. Based on our results, degree of cross-linking and drug conjugation capacity, as two important factors, affect simultaneously the thermal, morphological, and hydrolytic behavior of the carriers in film and microsphere forms. From the experimental data, with increasing the degree of cross-linking and drug conjugation capacity, the drug release was increased up to 12% w/w of glutaraldehyde; however, on further increasing the degree of cross-linking (18% w/w), the drug released in a burst manner. Also, regarding to the results from drug and enzyme conjugates, it is possible to design diversity of the chitosan derivatives based on different degree of cross-linking as well as enzyme conjugation capacity as reliable carriers.     

Novel blend microspheres of poly(vinyl alcohol) and succinyl chitosan for controlled release of nifedipine

Water-soluble succinyl chitosan (SCS) was synthesized by reacting succinic anhydride with –OH and –NH₂ reactive groups of chitosan (CS). The blend hydrogel microspheres were prepared from SCS with poly(vinyl alcohol) (PVA) by water-in-oil (w/o) emulsion cross-linking using glutaraldehyde (GA) as the cross-linking agent. Nifedipine (NFD), an antihypertensive drug having a plasma half-life of 2 h, was encapsulated giving encapsulation efficiency up to 92 % and its release was extended up to 12 h. Scanning electron microscopy (SEM) confirmed the spherical nature and smooth surfaces of the microspheres, while Fourier transform infrared spectroscopy (FTIR) confirmed succinylation of CS and chemical stability of NFD in the matrix. Thermogravimetry (TGA) and differential scanning calorimetry (DSC) characterized the SCS and the blend hydrogel microspheres. X-ray diffraction (XRD) and DSC were also used to study the crystalline or amorphous nature of NFD. Swelling and in vitro release experiments performed in pH 1.2 and 7.4 buffer media showed a dependence of blend composition, extent of cross-linking and pH of the media. The mechanism of drug release as analyzed by an empirical equation, suggested non-Fickian trends.     

Preparation of porous chitosan/agarose microsphere and its R‐phycoerythrin release properties

The chitosan microspheres (CS‐CL) were prepared by suspension crosslinking method and used as carriers of R‐phycoerythrin (R‐PE). In this study, R‐PE was loaded in the microspheres and released in vitro. The effects of pH value, temperature, ionic strength, and R‐PE concentration on loading efficiency and release behavior were discussed. A novel microsphere that contained agarose (CS‐AR MP) was prepared and the basic loading and releasing behavior for R‐PE of this kind of new microspheres were also investigated. The results showed that all these chitosan microspheres have the ability to control‐release R‐PE. The addition of agarose may somewhat accelerate the release rate of R‐PE from microspheres and reduce the capacity of adsorption for R‐PE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2759–2766, 2007     

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-...     

Controlled release of urea from chitosan microspheres prepared by emulsification and cross-linking method

Encapsulation of urea was performed in chitosan microspheres via emulsification followed by cross-linking with genipin, a natural cross-linker. The microspheres were prepared by varying different parameters, e.g., concentrations of chitosan, urea and cross-linker. The effect of these parameters on urea loading (%), urea content (%), entrapment efficiency (%) and release rate was studied. Higher amount of chitosan (1.0?g) and cross-linker concentration (0.75?mmol/g of chitosan) produced entrapment efficiencies of 99.0 and 78.5?%, respectively. Release rate was found to be dependent on the concentrations of urea, chitosan, cross-linker and temperature of the release medium. Higher concentration of loaded urea enhanced the release rate, whereas higher concentrations of chitosan and cross-linker reduced it. Higher temperature of the release medium improved the release rate. It was found that water uptake (%) increased through the increase of concentrations of urea and chitosan and decrease of that of cross-linker. Fourier transform infrared (FTIR) spectroscopy indicated the incorporation of urea in the chitosan microspheres. There was no significant interaction between chitosan and urea as evidenced by FTIR study. Surface of the urea-loaded microspheres appeared coarser and rough compared to that of unloaded microspheres as revealed by scanning electron microscopy.     

海藻酸钙/埃洛石载药微球的制备与缓释盐酸二甲双胍性能

缓释可提高药物利用率,降低其毒副作用。采用交联法制备了海藻酸钙/埃洛石载药微球,以载药微球对盐酸二甲双胍（MH）药物的包封率和缓释效果为考察对象,研究了载药微球的制备工艺和缓释性能,并通过SEM、FTIR和TGA对其结构进行了表征。结果表明：在交联温度为0℃、海藻酸钠用量为1g、埃洛石添加量为2g时,能得到较优的载药微球包封率（79.23%）。上述条件下制得的复合载药微球在pH=6.8的磷酸盐缓冲液中能有效缓释,且720min后缓释度可达85.83%,说明其具有较好的pH敏感性和缓释效果。SEM表明海藻酸钙颗粒与埃洛石在载药微球内部形成复合结构,FTIR表明MH主要以物理包埋的形式于载药微球中,TGA表明添加埃洛石可以提高复合材料在200℃以上的热稳定性。