CD274 and colonic neoplasm: Anti‐PD‐L1‐BGP6 can accurately discriminate the expression level of PD‐L1 in different cell lines in vitro and in vivo.[205] BDP‐in‐anti‐PD‐L1 NPS actively targets colon cancer due to antibody binding to the receptor and simultaneously facilitates NIR‐II imaging.[206] Er NPs with bright down‐conversion luminescence at 1600 nm have been used to dynamically image immunotherapy.