Fig. 4. (a) Cell viability of HUVECs treated with different concentrations of NH4ReO4, Re NCs and the oxidization products of Re NCs; (b) hemolysis test of different concentrations of Re NCs; (c) fluorescence images of 4T1 cells treated with/without a laser or with/without Re NCs. Scale bar: 0.5 mm; (d) concentration-dependent viabilities of 4T1 cells treated with Re NC dispersions under laser irradiation.
