Photoactivities of Two Vitamin B Derivatives and Their Applications in the Perpetration of Photoinduced Antibacterial Nanofibrous Membranes

Photoactivities and photoinduced antibacterial functions of two vitamin B₂ (VB₂) derivatives, riboflavin (RF) and flavin mononucleotide (FMN), were investigated by computational modeling and various experimental evaluations. Under photoirradiation, the ground state of both VB₂ derivatives could be excited to generate different reactive oxygen species (ROS) by undergoing different reaction paths. The formed ROS could nonselectively inactivate microorganisms. However, both RF and FMN exhibited negligible photoinduced antimicrobial activity in phosphate-buffered saline (PBS) solutions even at high concentrations. The study revealed that the affinity of both RF and FMN to microorganisms in different application media plays a key role due to the very short lifetime of the generated ROS. The speculation was proven by the preparation of a poly­(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane blended with RF or FMN, which could enhance the contact of the agents with microorganisms. The fabricated nanofibrous membranes containing both VB₂ derivatives (VBNFMs) showed great photoinduced antibacterial activity against Gram-negative Escherichia coli (E. coli) (99.999% bacterial reduction) and Gram-positive Listeria innocua (L. innocua) (99% bacterial reduction) under 20 min of ultra-violet A irradiation. The photoinduced antimicrobial performances of RF/PVA-co-PE and FMN/PVA-co-PE nanofibrous membranes were comparable. Interestingly, the durability of the photoinduced antibacterial functions of the prepared VBNFMs was questionable, due to the photodegradation of VB₂ in nanomaterials.