Spray Fabrication of Layer-by-Layer Antimicrobial N-Halamine Coatings

DEDICATION To my parents, thank you for always encouraging me to explore the world. v ACKNOWLEDGEMENTS I would to thank my advisor, Julie M. Goddard, for her guidance and support throughout my degree. Thanks are also due to the entire Bioengineering group, especially Luis Bastarrachea for his mentorship and advice. I would also like to extend my gratitude to my committee members, Amanda Kinchla and Lynne A. McLandsborough, for their time and recommendations. I would also like to thank Lynne A. McLandsborough for use of her microbiology laboratory, Sekar T. Dhanasekaran for his assistance with Atomic Force Microscopy, and Thomas J. McCarthy for the use of his ellipsometer. 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 layer-by-layer (LbL) fabrication have demonstrated the potential of this coating technology; however, spray LbL fabrication would enable more rapid coating and represents a more commercially translatable application technique. In this work, dip and spray LbL methods were used to coat polypropylene (PP) with N-halamine containing bilayers consisting of cross-linked polyethylenimine (PEI) and poly(acrylic acid) (PAA). Further experimentation with spray LbL fabrication used naturally occurring polyelectrolytes, chitosan and alginate. Materials were characterized using atomic force microscopy (AFM), ellipsometry, contact angle, fourier transform infrared spectroscopy, a chlorine content assay, and a dye assay for amine quantification. All methods of coating application exhibited a 99.999% (5-log) reduction against Listeria monocytogenes with application time for spray LbL taking less than 10% of the time required for dip LbL. Spray LbL fabrication of N-halamines is a rapid and inexpensive method to fabricate rechargeable antimicrobial surfaces.