Fig. 4

In vitro PA, fluorescence and ROS generation of the NPs. a PA spectra of RClosed and ROpen NPs. b PA intensities of RClosed and ROpen NPs at 700 nm as a function of molar concentration based on DTE-TPECM molecules. Error bars, mean ± s.d. (n = 3) for a, b. c PA amplitudes of RClosed NPs as a function of number of laser pulses (1.8 × 10⁴ pulses; 1.5 W cm⁻² laser and 20 Hz pulse repetition rate). d PA intensities excited with 680 nm pulsed laser of various agents at the same molar concentration (100 μM) based on MB, ICG, DTE-TPECM molecules and the repeat unit of SP. e Plot of A/A₀ versus different RONS. A and A₀ are the absorption intensity at 680 nm of RClosed NPs, SPNs, MB and ICG in the presence and absence of RONS (400 μM), respectively. Error bars, mean ± s.d. (n = 3) for (d, e). f PL excitation mapping and g fluorescence decay curve of ROpen NPs. h Plot of I/I₀ versus light irradiation time. The aqueous solution of RClosed NPs or ROpen NPs (10 μM based on DTE-TPECM) was exposed to 610 nm red light (0.3 W cm⁻²) and/or 365 nm UV light (0.1 W cm⁻²). i Plot of I/I₀ versus white light (0.25 W cm⁻²) irradiation time of ROpen NPs (10 μM based on ROpen-DTE-TPECM) in aqueous solution. I₀ and I are the PL intensity of DCF at 525 nm before and after light irradiation at designated time intervals in both h, i