Three dimensional mesoporous carbon nanospheres as carriers for chemo-photothermal therapy compared with two dimensional graphene oxide nanosheets

Recent years, photothermal therapy (PTT) as a noninvasive cancer treatment has attracted wide interests of researchers worldwide. Platforms which can transform near infrared (NIR) laser power into heat play vital roles in PTT. In this paper, mesoporous carbon nanospheres (MCN) and graphene oxide nanosheets (GO), two widely used platforms in cancer treatment were compared in photothermal effect induced by NIR as well as the drug loading and release behaviors of the model drug doxorubicin (DOX). MCN and GO were grafted with polyethylene glycol (PEG) to improve the biocompatibility and aqueous stability. The elevated temperature of MCN-PEG was obviously superior to GO-PEG both in vitro and cellular photothermal effect. MCN-PEG and GO-PEG showed photothermal stability under repeated NIR irradiation. Additionally, the photothermal conversion efficiency (η) of MCN-PEG was calculated to be 32.24 %, which was higher than that of GO-PEG (27.13 %). Both nanovehicles had the similar drug loading capacities, however, the accumulative release rate of DOX/MCN-PEG was 1.6 times higher than DOX/GO-PEG in the pH 5.0 phosphate buffer solutions (PBS) exposed to NIR laser. Moreover, the cell viability assays and cellular uptake experiments validated that DOX/MCN-PEG possessed more excellent synergetic effect in chemo-photothermal therapy with the combination index (CI) of 0.443 compared with DOX/GO-PEG (0.661).