Fig. 3
a The preparation of BTN@LND NPs and NIR-II PTT-triggered drug release. b DLS and transmission electron microscopy (TEM) image of BTN@LND NPs. c UV–Vis-NIR absorption spectra of free LND, BTN NPs, and BTN@LND NPs. d Concentration-dependent photothermal curves of BTN@LND NPs (1064 nm laser, 1.0 W cm−2). e Time-dependent infrared thermographs of BTN@LND NPs (0.1 mg mL−1, 1064 nm laser, 1.0 W cm−2). f Photothermal heating curves of BTN NPs with different power densities for comparison. g Five heating and cooling cycles of BTN NPs (0.1 mg mL−1, 1064 nm laser, 1.0 W cm−2). h Relevant in vitro PA images with different concentration. i Concentration-dependent PA intensities of BTN@LND NPs. Inset: relevant in vitro PA images. j NIR-II PTT-triggered LND release curves from BTN@LND NPs. Means ± SD, n = 3