In vitro cytotoxicity profiles. (a–d) The relative cell viabilities of B16 cells across the different treatment groups, including negative control, laser, HMPB@sPP@HA + laser at different concentrations, HMPB@sPP and HMPB@sPP@HA and 17-DMAG-HMPB@sPP@HA + laser at different concentrations, 17-DMAG and 17-DMAG-HMPB@sPP@HA at equivalent 17-DMAG concentrations. (e) The cell death rate at the highest concentration in each group. (f) The IC50 value for each group. (g) The CLSM images of B16 cells across the treatment groups stained by calcein-AM (for living cells) and PI (for dead cells), respectively. The laser irradiation intensity was 1.5 W cm−2, and the irradiation duration was 5 min.