Photothermal therapy is a clinical method to treat tumors in neurosurgery by using needle like fiber optic applicator, as evidenced by the US Food and Drug Administration approved instruments and several clinical trials currently in the US. However, this method is limited by the ability to deliver the applicator to the tumor sites, thus only applicable to localized and near surface disease or lesions. In addition, the thermal damage of healthy tissue is serious that additional methods are needed to cool down the applicator and define the thermal boundary during the therapy. Nanoparticles targeting cancer cells provide a new potential for photothermal therapy. In this talk, I will present our recent work on the development of bio-compatible copper sulfide (CuS) nanoparticles (NPs) that have a strong photothermal effect at 980 nm based on localized surface plasmon resonances. Due to a unique binding affinity to the cancer cells, CuS NPs coated with the functional layers have a high selectivity to the cancer cells and maintain an efficient photothermal effect from the CuS cores. In this talk I will also discuss different factors that influence the photothermal conversion efficiency.