Protein-modified hollow copper sulfide nanoparticles carrying indocyanine green for photothermal and photodynamic therapy

A novel phototherapy nanoplatform is prepared by coating hollow CuS nanoparticles with a bovine serum albumin–folic acid (BSA–FA) complex. The obtained CuS–BSA–FA nanoparticles are used as drug-delivery vehicles to transport a near-infrared-absorbing phototherapeutic agent (indocyanine green, ICG) into HeLa cells, after loading ICG onto CuS–BSA–FA. In this manner, a combined therapy approach is established consisting of photothermal therapy (by CuS–BSA–FA nanocarriers) and cytotoxic effects of photodynamic and photothermal therapy (by ICG upon 808 nm laser irradiation). The encapsulation of ICG onto CuS–BSA–FA significantly improves the stability and reduces the dark toxicity of free ICG. This therapeutic system exhibits an obviously higher photothermal heating effect and capability of 1O2 generation under laser irradiation compared with bare nanocarriers. In addition, the grafted FA segments on the surface of CuS–BSA–FA are proved to enhance the internalization of nanoparticles by FA-receptor-mediated endocytosis.