Fig. 1
Characterization of SPN-PT photophysical properties. A Representative TEM image and DLS analysis of SPN-PT. Scale bar = 500 nm. B Stability of averaged diameters of SPN-PT in PBS, MEM and FBS during the storage for 30 days. C Absorption spectra (red) and corresponding fluorescence emission spectra (black) of SPN-PT. D The UV absorption standard curve of SPN-PT aqueous solution at 700 nm. E Representative NIR-II fluorescence images (upper) and NIR-II fluorescence intensities with the concentrations of SPN-PT under 808 nm excitation with a 980 nm filter. F PA imaging spectra (680 to 820 nm) of SPN-PT (100 µg mL−1). G Representative PA images (upper) and the fitting curve of PA intensity of SPN-PT at 695 nm against concentrations (lower). H Normalized UV absorption stability of SPN-PT and Ce6 at 700 nm and 640 nm, respectively. The solutions were irradiated by a 635 nm laser at 0.75 W cm−2. I Photostability monitored of SPN-PT in PBS, MEM, FBS under continuous 808 nm laser excitation for 30 min. (a.u. arbitrary unit). Data were shown as mean ± SD, n = 3