Bioinspired pH-Sensitive Fluorescent Peptidyl Nanoparticles for Cell Imaging

As an invaluable tool for biomedical research, the green fluorescent proteins (GFPs) make tumor cells, amyloid plaques, and pathogenic bacteria equally visible. Here, inspired by the chromophore of GFPs, we constructed a tyrosine-based peptide that show green luminescence in the aggregation state. Similar to the optical property of GFPs, the tyrosine-based peptidyl nanoparticles are stabilized by intermolecular hydrogen bonding and emit fluorescence when the Tyr residues bear phenolic anions. In addition, the tyrosine-based peptide is cell-permeable and endosome-escaped when conjuncted with the GPGR motif of human immunodeficiency virus and can be used for stable cell imaging due to its excellent photostability, pH-sensitivity and biocompatibility in physiological conditions. The results provide a promising pathway to construct peptidyl bioluminescent agents for biomedical applications.