Controlling Properties and Cytotoxicity of Chitosan Nanocapsules by Chemical Grafting

The tunability of the properties of chitosan-based carriers opens new ways for the application of drugs with low water-stability or high adverse effects. In this work, the combination of a nanoemulsion with a chitosan hydrogel coating and the following poly (ethylene glycol) (PEG) grafting is proven to be a promising strategy to obtain a flexible and versatile nanocarrier with an improved stability. Thanks to chitosan amino groups, a new easy and reproducible method to obtain nanocapsule grafting with PEG has been developed in this work, allowing a very good control and tunability of the properties of nanocapsule surface. Two different PEG densities of coverage are studied and the nanocapsule systems obtained are characterized at all steps of the optimization in terms of diameter, Z potential and surface charge (amino group analysis). Results obtained are compatible with a conformation of PEG molecules laying adsorbed on nanoparticle surface after covalent linking through their amino terminal moiety. An improvement in nanocapsule stability in physiological medium is observed with the highest PEG coverage density obtained. Cytotoxicity tests also demonstrate that grafting with PEG is an effective strategy to modulate the cytotoxicity of developed nanocapsules. Such results indicate the suitability of chitosan as protective coating for future studies oriented toward drug delivery.     

虾青素纳米粒的制备及性能研究

为提高虾青素的稳定性,采用超声的方法将卵磷脂和壳聚糖在水相溶液中自聚集形成散性的纳米粒。对影响纳米粒的制备与性质的因素进行分析,发现在卵磷脂/壳聚糖比例为5∶1到20∶1(w/w)条件下,超声15 min可形成稳定的纳米包载体系。粒径范围在137.51~139.46 nm之间且带有正电荷,粒径分布均匀。在电镜下观察为不规则的球状。制备得到虾青素纳米粒的包封率和包载量为51.02%和10.34%。虾青素纳米载体在pH 1.2、pH 6.8和pH 7.4的条件下,72h内释放约66.97%、30.34%和28.19%,具有较好的控制缓慢释放的作用。可见,壳聚糖/卵磷脂纳米载体是理想的虾青素功能食品载体。     

芯-壳复合纳米颗粒及其纳米营养物制备技术的研究Ⅰ.儿茶素纳米胶囊的研制

利用分子自组装原理制备包封有儿茶素的壳聚糖纳米胶囊,探讨了pH值和壳聚糖与三聚磷酸钠(TPP)质量比对纳米颗粒形成及其性质的影响.通过控制壳聚糖与TPP质量比为1.3～3.0,可制备形态规则、分散性好、平均粒径为10～50 nm的球形纳米颗粒.经高效液相色谱法分析,儿茶素的包封率为30.54%～50.46%.本研究结果为进一步研制壳聚糖-功能蛋白芯-壳复合纳米颗粒及纳米营养物奠定了基础.     

负载戊唑醇的壳聚糖纳米胶囊的制备与性能研究

以戊唑醇为囊芯,壳聚糖和甲基丙烯酸甲酯为囊壁,采用自组装的方法制备了壳聚糖戊唑醇纳米胶囊。采用动态光散射仪(DLS)和透射电镜(TEM)对其粒径和形貌进行了表征,纳米胶囊的平均粒径(D50)为220 nm,分布系数(PDI)为0.23;经高效液相色谱仪测定,纳米胶囊的载药量为21.8%,包覆率为85.7%,体外释放192 h的释药率为65.97%。用带毒培养基法测试了其对3种木竹材霉菌的抑制性能。结果表明,与相同质量浓度(48.2 mg/L)的戊唑醇乙酸乙酯溶液相比,载戊唑醇纳米胶囊处理前20 d抑菌效果较低,但随着时间的延长仍能保持较高的抑菌活性,药剂处理40 d时对木霉、青霉、黑曲霉菌的抑菌率分别仍达70.6%、66.4%和89.1%。研究结果可为纳米胶囊木竹材防霉剂的开发奠定基础。     

新型两亲性多糖基戊唑醇纳米胶囊的制备及缓释性能研究

以羧甲基纤维素钠 (CMC-Na) 为原料,通过离子液体活化法使其与生育酚琥珀酸酯进行酯化反应,制备新型两亲性多糖基材料羧甲基纤维素钠衍生物 (CMCD),并利用傅里叶红外光谱 (FTIR)、核磁共振波谱 (1H NMR)、X-射线衍射 (XRD) 及热重 (TG) 分析表征其分子结构及热性能;采用超声/溶剂挥发法制备载戊唑醇CMCD纳米胶囊,并通过动态光散射 (DLS) 和透射电镜 (TEM) 测定该纳米胶囊的粒径及形貌,采用高效液相色谱法测定包封率、载药量及缓释性能;利用培养基法探究其抑菌效果。结果表明:成功合成了两亲性CMCD,其临界胶束浓度 (CAC) 为0.28 mg/mL;所制备的戊唑醇纳米胶囊的粒径为400~500 nm,包封率为50.8%,载药量为40.4%;缓释及抑菌试验结果显示,所制备的纳米胶囊48 h的最终累积释药率仅为77.78%,施药后12 d对山核桃干腐病菌菌丝生长的抑制率仍可达17.67%,而此时传统的戊唑醇悬浮剂(430 g/L)的抑制率已为0%。表明所制备的新型两亲性多糖基戊唑醇纳米胶囊具有良好的缓释性能及抑菌效果。