The role of surface modification in improving the effectiveness of CuS nanorods for cancer ablation therapy and antibacterial applications

We report a new methodology to synthesize CuS nanorods (CuS NRs) via hydrothermal route, and surface modified with chitosan (CS) and folic acid (FA) to demonstrate the role of surface modification in photo-thermal heat generation and cancer photo ablation therapy. The electron microscopy investigations showed the formation of rod-shaped CuS nanomaterial and the length and diameter of nanorods (NRs) were found to be ∼55 and 22 nm, respectively. The surface modification of CuS NRs was investigated by UV–Vis spectroscopy, FTIR spectroscopy, dynamic light scattering technique, and Raman spectroscopy. Without any compromise in photo-thermal heat generation, the surface modification significantly improved biocompatibility, cancer cell cytotoxicity, and anti-bacterial activity. The photothermal heat generation experiments with 808 nm laser light revealed that the temperature increase was found to be 54 ℃ for surface modified FA-CS@CuS NRs at 500 µg/mL which increased to ∼100 ℃ when the laser power intensity was increased from 0.5 to 1.5 W/cm2. The photothermal conversion efficiency (PCE) was estimated to be 38.6% for FA-CS@CuS NRs. Notably, the photothermal heat generation is significantly influenced by CuS NRs concentration and laser power intensity. The anticancer activity investigations against HCT116 cancer cells revealed enhanced cytotoxicity for cancer cells owing to synergistic effects of hyperthermia and generation of highly toxic hydroxyl radicals (·OH) induced by the release of Cu2+ions. The surface-modified FA-CS@CuS NRs showed excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. Hence, the proposed FA-CS@CuS NRs can be a suitable nanoagent for effective targeted anticancer and photothermal ablation treatment.