Facile synthesis of biocompatible L-cysteine-modified MoS ₂ nanospheres with high photothermal conversion efficiency for photothermal therapy of tumor

Photothermal therapy (PTT) can take advantage of the photothermal effects of photothermal agents to acquire the energy from laser irradiation and convert it into heat. This can intensively elevate the temperature of the surrounding environment to directly destroy the cancer cells. It is expected that PAs with strong absorption in near infrared (NIR) range might possess the ideal tissue-transparent feature and minimal damage to surrounding healthy tissues, beneficial to the practical application. Herein, well-dispersed L-cysteine modified MoS₂ (MoS₂-Cys) nanospheres with the average diameter of about 422 nm and strong NIR adsorption were successfully synthesized through a facile method. The as-prepared MoS₂-Cys nanospheres are composed of nanosheets with the average thickness of about 13.7 nm. The photothermal conversion efficiency of the as-prepared MoS₂-Cys nanospheres with the very low concentration of 50 μg/mL was determined to be 35% when exposed to 808 NIR laser at the power density of 0.8 W/cm², much higher than those of the previous reports with same dose and power density. MoS₂-Cys nanospheres possessed the good photothermal ablation effect to significantly inhibit the growth of tumor in vivo. Furthermore, MoS₂-Cys nanospheres did not exhibit detectable side effects, suggesting their good in vitro and in vivo biocompatibility.

Keywords: Biocompatibility; Molybdenum disulfide; NIR laser; Nanospheres; Photothermal therapy.