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

Herein, five Fe(II) complexes, viz., [Fe( N, N, N ) 2 ](ClO 4 ) 2, where N, N, N = 4′-phenyl-2,2′:6′,2″-terpyridine (Ph-tpy, Fe1 ), 4′-(4 aminophenyl) 2,2′:6′,2″ terpyridine (NH 2 -Phtpy, Fe2 ), 4-([2,2′:6′,2′′-terpyridin]-4′-yl)- N, N -dimethylaniline (NMe 2 -Phtpy, Fe3 ), 4′-( p -nitrophenyl)-2.2′:6′,2″-terpyridine (NO 2 -Phtpy, Fe4 ), and 4′-(4-trifluoromethylphenyl)-2,2’:6′,2′′-terpyridine (CF 3 -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 T 1 and S 0 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.