Fig. 4. (a) IR thermographic images of PBPGs at different concentrations acquired at 0, 1, 2, 3, 4, and 5 min (from left to right). (b) The corresponding photothermal conversion curves. (c) IR thermographic images of different samples with 500 μg mL⁻¹ concentration acquired at 0, 1, 2, 3, 4, and 5 min (from left to right). (d) Photothermal conversion curves of different samples with 500 μg mL⁻¹. (e) Photothermal stability of PBPGs for three consecutive cycles.