Dual drug delivery system of photothermal-sensitive carboxymethyl chitosan nanosphere for photothermal-chemotherapy

Aiming at high drug loading and controlled drug release in chitosan nanocarriers, this work constructed the photothermal sensitive carboxymethyl chitosan nanospheres carrier by introducing controllable heat-sensitive groups into carboxymethyl chitosan molecules. The combination therapy system based on photothermal-chemotherapy was established by virtue of the good photothermal conversion effect of ICG and the high chemotherapy efficiency of DOX. On the one hand, the carrier owned high drug loading and improved the stability of coated-drug. On the other hand, the nanospheres generated photothermal response through NIR irradiation to improve the drug release amount and to achieve the combined treatment effect of photodynamic therapy and chemotherapy. The structures of the nanospheres were fully characterized by Fourier transform infrared (FT-IR), nuclear magnetic resonance (¹H NMR) and scanning electron microscope (SEM). In vitro photothermal tests proved that the nanospheres had excellent light stability and photothermal conversion performance. The cytotoxicity test results showed that the nanospheres had no obvious toxicity, but the drug-loaded nanospheres could effectively inhibit the growth of HepG-2 cells via photo-response to release DOX and ICG for achieving photothermal-chemotherapy under NIR irradiation.