Based on our previous research on photoacoustic imaging of Cu(II) in the brain (Angewandte Chemie International Edition, 2024, 63, No. e202318340), we have further advanced the development of photoacoustic probes for Cu(II) imaging in tumors. We incorporated β-galactoside and benzyl fluoride groups into PA_Cu3, resulting in the newly synthesized probe, β-gal-PA_Cu2, which exhibits excellent tumor-targeting capabilities. Furthermore, this probe can undergo self-immobilization to proteins via covalent cross-linking, significantly extending its retention time at the imaging site. This strategy facilitates high-resolution, precise in situ imaging and quantification of Cu(II) within tumor cells. Congrates to Qian on this achievement! For more details, please read the paper online via the link: https://pubs.acs.org/doi/full/10.1021/cbmi.4c00115.