Influence of Branched Polyester Chains on the Emission Behavior of Dipyridamole Molecule and Its Biosensing Ability

Toward the development of the smart biosensing drug carrier, integration of dye molecules with polymeric chain has been an emerging method in recent years. In this perspective, dipyridamole (Dip)-based branched poly(l-lactide) (PLLA) and branched polycaprolactone (PCL) have been synthesized by ring-opening polymerization. After polymerization, the influence of the polyester chains on the Dip emission behavior has been studied systematically in this work. Dip-PLLA has undergone C=O···N=C interaction in ground stage, leading to intramolecular charge transfer in the excited state. Limited availability of the C=O in PCL chains resists such interactions with Dip molecule. So, this structural availability of the C=O group in the polymeric chains influences the color change between Dip-PLLA (green fluorescence) and Dip-PCL (blue fluorescence). To visualize the biosensing ability of Dip-PLLA and Dip-PCL, hollow microspheres have been prepared by the double-emulsion solvent evaporation method, and the prepared microspheres cells uptake has been visualized by fluorescence imaging.