Temperature changes during the heating and cooling cycles were measured with a thermocouple inserted into the solution. All four materials showed high photothermal conversion efficiencies, ranging from 67.3 ± 8.4 to 75.9 ± 4.1 % (Table , Table ). The maximum temperatures changes observed ranged from 4.8 -8.7 °C (Figure ). The highest temperature changes were observed in the materials with the highest molar absorptivity at 785 nm, highlighting the importance of selecting materials with strong absorbance at the therapeutic wavelength to accomplish effective photothermal therapy. Importantly, no decrease in photothermal conversion efficiency or maximum temperature was observed for any of the materials following three irradiation cycles, indicating good photostability of the materials (Figure , Table ).