(a) The photothermal heating curves of GNR, GNR@mSiO2, GNR@Ag@mSiO2, and GNR@Ag@mSiO2-MB suspensions under 785 nm laser irradiation (0.6 W/cm2) for 600 s. The photothermal heating profiles (b) and IR thermal images (c) of GNR@Ag@mSiO2-MB suspension with different volumes (12, 16, 20, and 24 µL of 100 µg/mL) under 785 nm laser irradiation (0.6 W/cm2) for 600 s. (d) The photothermal heating curves of GNR@Ag@mSiO2-MB under 785 nm (0.6 W/cm2) for 600 s, followed by natural cooling down with the laser turning off for 1200 s. (e) Plots of the cooling period versus the negative natural logarithm of driving force temperature. (f) Repeated heating/cooling profiles for five cycles.