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

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/mL,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.