(A) Schematic illustrating the release mechanism for AuNCs coated with smart polymers. (B) Absorption spectra of alizarin-PEG released from the copolymer-covered AuNCs upon exposure to a pulsed NIR laser (power density: 10 mW/cm2) for 1, 2, 4, 8 and 16 min and (C) upon exposure to the laser for 2 min at 10, 25 and 40 mW/cm. The insets show the accumulated concentrations of alizarin-PEG released from the AuNCs. (D) Cell viability of samples after irradiation with the laser (C-1) for 2 min in the absence of AuNCs, (C-2) in the presence of empty AuNCs, and (2/5 min) for 2 and 5 min in the presence of Dox-loaded AuNCs.31 (E) Fluorescence microscopy images of the gelatin phantom with dye-loaded AuNCs after exposure to HIFU at a power of 10 W for 20 min. Scale bars: 500 μm.32