Continuous Fabrication of Antimicrobial Nanofiber Mats Using Post-Electrospinning Functionalization for Roll-to-Roll Scale-Up

The facile fabrication of antimicrobial fiber mats with surface-attached quaternary ammonium compounds (QACs) as the contact-killing antimicrobials was demonstrated. The entire process was designed to be scaled up to a continuous roll-to-roll (R2R) process using a customized R2R manufacturing platform that combines a multinozzle electrospinning technique to generate homogeneous fiber mats and a wet chemical dipping cycle with UV treatment for post-functionalization. A thiol-ene click reaction was used to chemically tether a QAC thiol (QAC-SH) on the surface of electrospun fibers containing an alkene functional handle (allyl-TPU). The control of the electrospinning conditions and fiber morphology was investigated by changing the solution concentrations and the tip-to-collector distance (TD). A critical solution concentration correlated to the onset of chain entanglement was necessary to obtain uniform fiber morphology. Surface functionalization of the covalently attached QAC-SH was quantified by fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS) following the click reactions. Antimicrobial assays demonstrated the rapid (>30% in 15 min) and sustained (1-3-log reduction in 4 and 24 h) contact-killing efficacies of QAC-SH-functionalized fiber mats against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, further demonstrating the feasibility of implementing the post-functionalization process in a continuous R2R manner.