Fig. 2. Photo-to-heat energy conversion performance of Nano-BFF.

a, e Photothermal conversion curves of Nano-BFF aqueous solution (200 μg mL⁻¹) under a 808 nm and e 1064 nm laser irradiation at varied power densities. b, f IR thermal images of Nano-BFF aqueous solution at varied concentrations under b 808 nm (1.5 W cm⁻²) and f 1064 nm (1.5 W cm⁻²) laser irradiation. c, g Photothermal effect of Nano-BFF aqueous solution after irradiation with c 808 nm and g 1064 nm lasers and linear fitting curves between time and −lnθ acquired from the cooling process. d, h On–off curves of Nano-BFF aqueous solution (100 μg mL⁻¹) upon d 808 nm (1.5 W cm⁻²) and h 1064 nm (1.5 W cm⁻²) laser irradiation. i, j Power density of i 808 nm and j 1064 nm lasers after penetration through tissues with different thicknesses. k Real-time temperature, and l temperature variations of Nano-BFF aqueous solution upon the laser irradiation after the penetration into tissues with increasing skin thickness.