Characterization of BPLPAT polymer structure. (a) Schematic and chemical structure of BPLPAT pre-polymers. (b) Schematic of crosslinked BPLPAT structure. (c) Schematic of functionalities (fluorescence imaging, PA imaging, and conductivity that promotes cell communications) of crosslinked BPLPATs. (d) ATR-FTIR spectra of AT, BPLP, and BPLPAT pre-polymers. Insert: quinoid ring to -C(=O)OR ratios increase with the increasing concentration of AT in polymer syntheses. (e) 1H NMR spectrum of AT, BPLP, and BPLPAT pre-polymers. Insert: AT to OD molar ratios increase with the increasing concentration of AT in polymer syntheses.