Nanoassembly of UCST polypeptide for NIR-modulated drug release

Abstract

Multi-L-arginyl-poly-L-aspartate (MAPA), also known as cyanophycin, is a zwitterionic polypeptide. The upper critical solution temperature (UCST) response of the insoluble fraction (iMAPA) upon crosslinking with hyaluronic acid (HA) was found to be preserved over a wide pH range. The thermal reversibility of iMAPA-HA was further employed to encapsulate doxorubicin (dox) at different weight ratios of dox/polymer with and without AuNP incorporation so as to obtain light responsive nanoassemblies. Dox loading was found to be a function of both dox concentration and the presence of AuNP. Thus a maximum encapsulation efficiency of about 60% was observed for 3 mg dox/mg polymer with AuNP as compared to 35% without AuNP. The size of these nanoassemblies exhibited a range of 30-50 nm, and these nanoassemblies also displayed stability at 4 degrees C by morphology and dox retention for at least 4 weeks in PBS. Upon periodic irradiation for 30 s with an 808 nm laser, altering the irradiation intensity and duration could selectively manipulate the release profile and percentage by a photothermal effect. The results present a delivery system with controllable light-regulated release.