A core–shell double-layer structured polylactic acid/chitosan delivery system containing large molecular protein

Polylactic acid (PLA)/chitosan (CS) microparticles (MPs) containing large protein molecules of ovalbumin (OVA) were constructed for drug delivery, simply achieved by self-assembly of PLA and CS using water-in-oil-in-water (w/o/w) double emulsion–evaporation technique. The encapsulation efficiency (EE), drug loading capacity (LC), and in vitro drug release behavior of MPs were studied by BCA assay. The effects of concentrations of biopolymers and protein on EE, LC, as well as average hydrated particle size, were investigated in detail. It was found that the resultant EE of MPs achieved 76.4 ± 0.1% under the optimal conditions. Besides, by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM), MPs were observed as spherical and possessed a core-shell double-layer structure. In addition, the cytotoxicity of MPs and the structural integrity of entrapped OVA were studied by MTT assay and polyacrylamide gel electrophoresis (PAGE) analysis, respectively. It was shown that PLA/CS MPs have low toxicity on cells and the structure of the protein is still an integral structure in the intestine. All these results suggested that PLA/CS MPs containing a large protein molecule have potential applications in the area of protein delivery.