Development of antimicrobial stainless steel via surface modification with N-halamines: Characterization of surface chemistry and N-halamine chlorination

N-halamine modification of materials enables the development of antimicrobial materials whose activity can be regenerated after exposure to halogenated sanitizers. Surface and bulk modification of polymers by N-halamines has shown great success, however, modification of inorganic substrates (e.g., stainless steel) remains an area of research need. Herein, we report the covalent surface modification of stainless steel to possess rechargeably antimicrobial N-halamine moieties. Multilayers of branched polyethyleneimine and poly(acrylic acid) were immobilized onto the surface of stainless steel and the number of N-halamines available to complex chlorine was quantified. Samples were characterized through contact angle, Fourier transform infrared spectroscopy, ellipsometry, dye assay for amine quantification, and X-ray photoelectron spectroscopy. Increasing the number of multilayers from one to six increased the number of N-halamines available to complex chlorine from 0.30 +/- 0.5 to 36.81 +/- 5.0 nmol cm-2. XPS and FTIR confirmed successful covalent layer-by-layer deposition of the N-halamine multilayers. The reported layer-by-layer deposition technique resulted in a greater than seven-fold increase of available N-halamine compared to prior reports of N-halamine surface modifications. The N-halamine modified steel demonstrated antimicrobial activity (99.7% reduction) against the pathogen Listeria monocytogenes. Such surface modified stainless steel with increased N-halamine functionality, and therefore potential for rechargeable antimicrobial activity, supports efforts to reduce cross-contamination by pathogenic organisms in the food and biomedical industries. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012