基于酪蛋白酸钠/EGCG/阿拉伯胶自组装构建EGCG纳米粒及其形成机制研究

Fabrication and Formation Mechanism of EGCG-loaded Nanoparticles Based on the Self-assembly of Sodium Caseinate,EGCG and Gum Arabic

本文通过酪蛋白酸钠(sodium caseinate、SC)、表没食子儿茶素没食子酸酯(epigallocatechin gallate、EGCG)和阿拉伯胶(gum arabic、GA)三者自组装构建EGCG纳米粒(SC-EGCG-GA纳米粒),研究形成高载药量且稳定性好的纳米粒的条件,并考察纳米粒的贮藏稳定性,同时采用透射电子显微镜(transmission electron microscope、TEM)对纳米粒的微观形貌进行表征,最后借助红外光谱(fourier transform infrared spectroscopy、FTIR)、荧光光谱和圆二色谱(circular dichroism、CD)对纳米粒结构进行表征,探讨纳米粒形成机制。结果发现,形成高载药量且稳定性好的SC-EGCG-GA纳米粒的条件为EGCG/SC/GA浓度比2∶5∶5,SC和GA总浓度1.5 mg/m L,p H4.2,NaCl浓度10 mmol/L。此时形成的纳米粒粒径约为173.52 nm,Zeta电位约为-19.94 m V,包封率约为62.82%,载药(EGCG)量达到338.49μg/mg,在4℃下贮藏30 d后仍保持稳定。透射电镜结果显示纳米粒呈球形。根据FTIR、荧光光谱和CD结果,推测纳米粒可能的形成机制为首先SC与EGCG通过氢键结合,GA加入后SC中的NH3+和GA中的COO-则通过静电相互作用结合,从而抑制SC与EGCG过度结合与聚集,三者通过以上非共价作用自组装形成纳米粒。

EGCG-loaded nanoparticles( SC-EGCG-GA nanoparticles) were fabricated based on the self-assembly of sodium caseinate( SC),(-)-Epigallocatechin-3-gallate( EGCG) and gum arabic( GA) and the process parameters to form stable nanoparticles with high drug loading content were investigated. Meanwhile,the morphological attributes of nanoparticles were characterized by transmission electron microscopy( TEM) and the storage stability of nanoparticles was studied.Furthermore,the mechanism of the formation of nanoparticles was researched by infrared spectroscopy( FTIR),fluorescence spectroscopy and circular dichroism( CD).The results revealed that the formation of stable EGCG-loaded nanoparticles with high drug loading content was achieved under the following conditions: the concentration ratio of EGCG,SC,GA was 2 ∶ 5 ∶ 5,the total concentration of SC and GA was 1.5 mg/m L,pH value was 4.2,and the concentration of NaCl was 10 mmol/L. Under these process conditions,the particle size of nanoparticles was about 173.52 nm,the zeta potential was about-19.94 mV,the encapsulation efficiency was about 62.82%,and the drug loading content reached up to 338.49 μg/mg. Moreover,the nanoparticles were remained stable after storage of one month at 4 ℃.TEM results showed that the nanoparticles were spherical in shape. According to the results of FTIR,fluorescence spectroscopy as well as CD,the mechanism of the formation of nanoparticles was concluded as follows: Firstly,EGCG bound to EGCG with the driving force of hydrogen bonding.Subsequently,with the addition of GA,electrostatic interaction occurred between the positively charged amino of SC and negatively charged carboxyl of GA,which could inhibit the excessive combination and aggregation between SC and EGCG.The two non-colvant interactions mentioned above induced the self-assembly of SC,EGCG and GA to form EGCG-loaded nanoparticles.