Antimicrobial efficacy of N-halamine coatings prepared via dip and spray layer-by-layer deposition

Antimicrobial coatings in which the active agent (e.g. N-halamine) can regenerate activity represent a promising way to prevent microbial cross-contamination. A reported method for applying coatings containing antimicrobial N-halamines is layer-by-layer (LbL) application of polyelectrolytes which form N-halamines upon cross-linking. Prior reports on dip LbL have demonstrated the potential of this technology; however, spray LbL represents a more commercially translatable technology. In this work, dip and spray LbL methods were used to coat polypropylene (PP) with N-halamine containing bilayers of cross-linked polyethyleneimine (PEI) and polyacrylic acid (PAA). Materials were characterized using atomic force microscopy, ellipsometry, contact angle, Fourier transform infrared spectroscopy, and colorimetric assays for chlorine and amine contents. Both methods exhibited >99.999% reduction against Listeria monocytogenes with application time for spray LbL taking 6% of the time required for dip LbL. Spray LbL fabrication of N-halamines is a rapid and inexpensive method to fabricate rechargeable antimicrobial surfaces.