Porphyrin-Polymer as a Photosensitizer Prodrug for Antimicrobial Photodynamic Therapy and Biomolecule Binding Ability

This study presents the development and characterization of a novel porphyrin-Jeffamine polymer conjugate designed to function as a photosensitizer prodrug for antimicrobial photodynamic therapy (aPDT). The conjugate features a photosensitive porphyrin unit covalently attached to a biocompatible polymer backbone, with enhanced solubility, stability, and bioavailability compared to those of the free porphyrin derivatives. The photophysical properties were studied using transient absorption spectroscopy spanning the fs-μs time scales in addition to emission studies. The production of reactive oxygen species upon photoactivation enabled effective bacterial cell killing. Spectroscopic studies confirmed strong binding of the conjugate to DNA through intercalation, likely disrupting DNA replication and transcription. Interaction studies with bovine serum albumin demonstrated substantial serum protein binding, which may positively impact the pharmacokinetics and biodistribution. Overall, this porphyrin-polymer conjugate offers a multifunctional theranostic platform, combining antimicrobial action with DNA and protein binding potential, positioning it as a promising candidate for aPDT and bioimaging applications.