Photothermo-responsive Cu7S4@polymer nanocarriers with small sizes and high efficiency for controlled chemo/photothermo therapy

Drug delivery systems (DDSs) have been getting more and more attention in the field of cancer therapy with the development of nanotechnology. But remote and noninvasive controlled drug release for improving treatment efficacy and reducing side effects faces great challenge. We report a kind of “smart” nanocomposites (NCs) that is sensitive to the surrounding temperature by grafting a layer of thermosensitive polymer, poly(N-isopropylacrylamide) (pNIPAm), on the surface of single Cu7S4 nanoparticle (NP) via atomtransfer radical polymerization (ATRP). These NCs demonstrate a photothermal conversion efficiency of 25.4% under 808-nmnear infrared (NIR) light irradiation and a drug loading content of 19.4% (drug/total NCs, w/w) with a lower critical solution temperature (LCST) of ~38°C. At normal physiological temperature (37°C), only 10.8% of the loaded doxorubicin (DOX) was released at physiological pH value (pH 7.4) within 10 h. In the presence of 808-nm irradiation, due to the temperature increment as a result of photothermal effects, DOX was rapidly released.