Fig. 2
The oxygen release of O2-PPSiI triggered by NIR. A The UV–vis-NIR spectrum of O2-PPSiI at different concentrations. B Time constant for heat transfer from the O2-PPSiI was calculated to be 111.21 with the comparison of the linear time data deriveed from the cooling period to the negative natural logarithm of driving force temperature. C Photothermal effect of aqueous dispersion of O2-PPSiI under irradiation by NIR laser (808 nm, 2 W cm−2). D Photothermal-heating curves of O2-PPSiI in different powers. E The oxygen release from O2-PPSiI with NIR laser irradiation. F The O2 retention in O2-PPSiI nanosystem within 24 h. G Ultrasonography for the water and O2-PPSiI solution before and after the NIR laser irradiation in vitro. H TEM images of O2-PPSiI nanosystem at 60 ℃. I Fluorescence images (scale bar: 20 µm) of intracellular O2 variation after different treatment probed with RDPP J Photothermal pictures of the tumor region irradiated with 808 nm NIR laser (1.5 W/cm2) after 8 h of drug administration in the MDA-MB-231 tumor-bearing nude mice K Ultrasonography for the tumor at baseline, intravenously injected with O2-PPSiI before and after the NIR laser irradiation in vivo