海藻酸包衣的季铵化壳聚糖纳米粒用于胰岛素口服给药的研究

摘要

In the present work,we aimed to develop alginate-coated chitosan nanoparticles for oral insulin delivery.The N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (HTCC) was synthesized,and the quatemized chitosan nanoparticles (HTCC-T NPs) were prepared by ionic gelation of HTCC using tripolyphosphate (TPP).The alginate-coated quatemized chitosan nanoparticles (HTCC-A NPs) were prepared by coating HTCC-T NPs with alginate (ALG) solution under mild agitation.Particle size,zeta potential,surface morphology,drug loading and entrapment efficiency of HTCC-A NPs were characterized using Zeta-sizer,TEM and HPLC assays.It was found that HTCC-A NPs exhibited uniform spherical particles with the size of (322.2±8.5) nm and positive charges (14.1±0.6) mV.Our data showed that the release behavior of HTCC-A NPs was quite different from that of HTCC-T NPs (without ALG coating) when incubated with various medium at different pH values in vitro,suggesting that ALG coating over the HTCC-T NPs improved the release profile of insulin from the NPs for a successful oral delivery.The ALG coating could also improve the stability of insulin against enzymatic degradation.From circular dichroism spectrum,it was revealed that HTCC-A NPs were capable of maintaining the conformation of insulin.The relative pharmacological bioavailability of HTCC-A NPs was 8.0％±2.5％ by intraduodenal administration.The HTCC-A NPs significantly increased (P＜0.05) the relative pharmacological availability (2.2 folds) compared with HTCC-T NPs after oral administration.HTCC-A NPs significantly enhanced the in vivo oral absorption of insulin and exhibited promising potentials for oral delivery.%本研究的目的是开发海藻酸包衣的壳聚糖纳米粒口服递送胰岛素.采用三聚磷酸钠(TPP)离子交联作用将N-[(2-羟基-3-三甲基铵)丙基]壳聚糖氯化物(HTCC)制备得到季铵化壳聚糖纳米粒(HTCC-T纳米粒),然后在温和搅拌条件下滴加入海藻酸钠溶液,进一步形成海藻酸包衣季铵化壳聚糖纳米粒(HTCC-A纳米粒).分别采用粒度仪、透射电镜和HPLC分析对HTCC-A纳米粒进行了粒径、zeta电位、表面形态、载药量和包封率的表征.结果表明,HTCC-A纳米粒为均匀的球形颗粒,大小为(322.2±8.5) nm,表面带有正电荷((14.1±0.6)mV).体外释放结果表明,在不同pH值的释放介质中,HTCC-A纳米粒的释放行为与HTCC-T纳米粒(未用海藻酸包衣)有很大的不同,这表明海藻酸包衣可以显著改善纳米粒中胰岛素的释放行为.同时,体外酶解试验和圆二色散图谱进一步证实,海藻酸包衣可以显著改善纳米粒中胰岛素结构稳定性.HTCC-A纳米粒十二指肠给药的相对药理生物利用度为8.0％±2.5％.与HTCC-T纳米粒口服给药相比,HTCC-A纳米粒的相对药理生物利用度显著增加(P＜0.05),是HTCC-T纳米粒的2.2倍.由此可见,海藻酸包衣季铵化壳聚糖纳米粒(HTCC-A纳米粒)将可能成为一种有效的口服递送载体系统用于提高胰岛素的体内口服吸收效果.