Fig. 1

A NIR absorption (black line) and NIR-II fluorescence emission spectra of FEPT (red line) (solvents: water). B The absorption spectra of FEPT after different times of laser irradiation (808 nm, 1.0 W/cm²). C Zeta potentials of FEP and FEPT in water. Heating curves of FEPT upon 808 nm laser irradiation with D various powers and E different concentrations upon 808 nm laser irradiation. F IR thermal images of heating process of various concentrations of FEPT upon 808 nm laser irradiation. G Photothermal stability of FEPT (50 µM). Curves showing the temperature change of FEPT with five ON/OFF cycles involving irradiation with an 808 nm laser (1.0 W/cm²) for more than one hour followed by passive cooling. H Photothermal conversion performance curves of FEPT. I-K Measurement of ¹O₂ production in 4T1 cells after pre-incubation with FEP or FEPT under 808 nm laser irradiation. L Plots of relative absorbance of ABDA of different groups in PBS. A₀ and A are absorbances of ABDA at 380 nm before and after 808 nm laser irradiation for ¹O₂, respectively