Bovine Serum Albumin Amplified Reactive Oxygen Species Generation from Anthrarufin-Derived Carbon Dot and Concomitant Nanoassembly for Combination Antibiotic–Photodynamic Therapy Application

Abstract

Amplification of reactive oxygen species (ROS) generation through covalent conjugation of bovine serum albumin (BSA) with newly synthesized, ROS-producing carbon dots (CDs) upon visible light irradiation is reported for the first time. Derivatization of surface carboxyl functional groups of Anthrarufin-derived, green-emitting CD with the amine functionality of BSA ushers distinct changes in the photophysics of CD including an unprecedented ∼50 nm shift in its excitation maxima, decrease in fluorescence lifetime, and concomitant increase in ROS generation. Substantial conformational changes of BSA were witnessed upon conjugation with CD, rendering the BSA-CD conjugate resistant to pepsinolysis. A protease-proof nanoassembly was derived from the BSA-CD conjugate through desolvation that simultaneously hosts a prototype antibiotic and generates ROS with excellent efficiency, making it an attractive platform for antibacterial photodynamic therapy (A-PDT) applications. Systemic annihilation of both Gram-positive and -negative bacteria was achieved with the BSA-CD nanoassembly and envisioned as alternatives to traditional photosensitizers.