“…Following incubation for another 24 h, the cells were washed with PBS, and the cell viability was measured using the CCK-8 method. 41 To further study the photothermal effect of ICG@COF NPs, the cell staining experiment was carried out using calcein-acetyl hydroxymethyl ester (Calcein-AM) and propidium iodide (PI) as fluorochromes, which could stain the living and dead cells, respectively. Specifically, 4T1 cells (3 Â 10 3 ) were inoculated in 96-well plates with ICG@COF NPs.…”