Colloids and Surfaces B: Biointerfaces 122 (2014) 294–300 Contents lists available at ScienceDirect Colloids and Surfaces B: Biointerfaces jo ur nal ho me p ag e: www.elsevier.com/locate/colsurfb Air-ozonolysis to generate contact active antimicrobial surfaces: Activation of polyethylene and polystyrene followed by covalent graft of quaternary ammonium salts Tania Fadida a,b , Yulia Kroupitski a,b , Uri M. Peiper c , Tatyana Bendikov d , Shlomo Sela (Saldinger) a , Elena Poverenov a,∗ a Department of Food Quality and Safety, The Volcani Center, ARO, PO Box 6, Bet Dagan 50250, Israel b Department of Biochemistry, The Hebrew University of Jerusalem, Rehovot 76100, Israel c Department of Agricultural Engineering, The Volcani Center, ARO, PO Box 6, Bet Dagan 50250, Israel d Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel a r t i c l e i n f o Article history: Received 11 May 2014 Received in revised form 25 June 2014 Accepted 2 July 2014 Available online 10 July 2014 Keywords: Air-ozonolysis Contact active surface Quaternary ammonium salts Antimicrobial surface Polystyrene Polyethylene a b s t r a c t Air-ozonolysis was revealed as an accessible and effective approach for surface activation and fur- ther functionalization of hydrocarbon polymers. Antimicrobial contact active polyethylene (PE) and polystyrene (PS) were designed by generation on their surfaces OH-functional groups and covalent graft of dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (C 18 -TSA) quaternary ammonium salt. The shortened analog, trimethyl [3-(trimethoxysilyl) propyl] ammonium chloride (C 1 -TSA), was also covalently attached to the activated PE and PS surfaces. X-ray photoelectron spectroscopy (XPS) and FTIR confirmed the surface modifications. Scanning electron (SEM) and confocal microscopy were utilized to monitor surface morphology and bacteria interactions. The antimicrobial effect of the C 18 -TSA grafted polymer surfaces was demonstrated on Gram-negative and Gram-positive bacteria species including human pathogen, Salmonella enterica. The shorter C 1 -TSA grafted polymers did not demonstrate bacteri- cidal activity, suggesting the critical role of the alkyl chain length. The described strategy may establish a new general and safe platform for future development and application of contact active antimicrobial polymers. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Material surfaces are most prone to bacterial colonization that causes adverse effects in various areas, resulting in contamina- tion of medical devices, food contamination and biofouling [1]. To reduce bacterial adhesion and proliferation, contact active antimicrobial approaches were developed [2,3]. Contact active approach involves a durable (usually covalent) linkage of an antimicrobial moiety to a material’s surface. Being surface linked, the antimicrobial agent is not consumed or released, providing important advantages in terms of human and environmen- tal safety [4]. In addition, such active surfaces can be reused multiple times. Due to these environmental and operational advantages, contact active antimicrobial materials (CAAM), are of high research and applicative interest [4,5]. Contact active surface ∗ Corresponding author. Tel.: +972 3 9683354; fax: +972 3 968 3692. E-mail address: elenap@volcani.agri.gov.il (E. Poverenov). modifications were achieved through the chemical grafting of antimicrobial polymers, such as N-alkylated poly(4- vinylpyridine) [3], poly(4-vinyl-N-methylpyridinium iodide) [6], poly(butylmethacrylate)-co-poly(Boc-aminoethyl methacry- late) [7], covalent linkage of quaternary derivatives of acrylic acid [8] and grafting of many others antimicrobial moieties [9]. An additional domain in contact active research involves surface linkage of antimicrobial peptides [9–12]. Polyethylene (PE) and polystyrene (PS) are among the most prevalent polymers that are used in all areas of modern life, ranging from various packaging material to medicinal equipment. PE and PS have no inherent heteroatom functional groups, and therefore surface activation is required for binding of an antimicrobial moiety to these polymers. Chemical activation methods that utilize strong oxidative agents such as chromic, nitric or sulfuric acids, potassium permanganate and hydrogen peroxide can generate functional groups on the polymer surface [13]. However, such treatments produce hazardous chemical waste and may cause undesirable changes of the bulk polymer properties. Physical approaches such http://dx.doi.org/10.1016/j.colsurfb.2014.07.003 0927-7765/© 2014 Elsevier B.V. All rights reserved.