Fe(II)-Photoantibiotics for Potential Antibacterial, Antibiofilm, and Infective Wound Healing Applications in Rat Model

Abstract

Herein, five Fe(II) complexes, viz., [Fe(N,N,N)2](ClO4)2, where N,N,N = 4′-phenyl-2,2′:6′,2″-terpyridine (Ph-tpy, Fe1), 4′-(4 aminophenyl) 2,2′:6′,2″ terpyridine (NH2-Phtpy, Fe2), 4-([2,2′:6′,2′′-terpyridin]-4′-yl)-N,N-dimethylaniline (NMe2-Phtpy, Fe3), 4′-(p-nitrophenyl)-2.2′:6′,2″-terpyridine (NO2-Phtpy, Fe4), and 4′-(4-trifluoromethylphenyl)-2,2’:6′,2′′-terpyridine (CF3-Phtpy, Fe5) were developed and screened for their visible-light-triggered antibacterial activity. Fe1-Fe5 exhibited absorption at ca. 450-600 nm, beneficial for antibacterial photodynamic therapy (aPDT) under visible light exposure. The excellent photostability and ideal energy gap between T1 and S0 of the complexes made them good photosensitizers for aPDT. Fe5 had the best antibacterial activity against Escherichia coli and Bacillus subtilis upon exposure to 400-700 nm (10 J cm-2) light due to reactive oxygen species (ROS) generation. Further, Fe5 showed antibiofilm activity on different medical-grade biomaterials and devices. Biocompatibility of Fe5 was validated using in vivo and chicken embryonic models (in ovo). Moreover, in vivo studies showed that Fe5 efficiently healed infected wounds within 9 days. © 2025 American Chemical Society.