Fig. 6

PA/US imaging of HPDC NPs in vitro and in vivo. A In vitro US images in CEUS of HPDC NPs at varying radiation times (pre-irradiation and 1 to 5 min post-irradiation) and the corresponding echo intensity values (1 W cm⁻²). B In vivo US images in CEUS of lymph nodes after the subcutaneous injection of HPDC pre- and post-irradiation (1.5 W cm⁻² for 2 and 5 min). C The in vivo echo intensity values in CEUS. Data are presented as mean ± standard and Student’s two-tailed t test (*p < 0.05, **p < 0.01) (n = 3 per group). D In vitro PA images and the fitted curves between PA values with varying concentrations of HPDC NPs (25, 50, 100, 200, and 400 ppm). E PA images in metastatic lymph nodes after the subcutaneous injection of HPDC NPs at different times. F PA signal intensity values at lymph nodes at varied intervals post-injection