Contents lists available at ScienceDirect Reactive and Functional Polymers journal homepage: www.elsevier.com/locate/react Silver nanoparticles grafted onto PET: Effect of preparation method on antibacterial activity H.Y. Nguyenova a, ⁎ , B. Vokata b , K. Zaruba c , J. Siegel a , Z. Kolska d , V. Svorcik a , P. Slepicka a , A. Reznickova a a Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic b Department of Biochemistry and Microbiology, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic c Department of Analytical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic d Faculty of Science, J.E. Purkyne University, 400 96 Usti nad Labem, Czech Republic ARTICLE INFO Keywords: Nanoparticle Grafting Plasma Polymer Antibacterial activity ABSTRACT Incorporating silver nanoparticles (Ag NPs) into surface structure is one of the way to prepare antibacterial surfaces. This study focuses on preparation of antibacterial polymer surface by grafting polyethylene ter- ephthalate (PET) with Ag NPs differing by method of preparation. Ag NP dispersions were synthesized by chemical (Ag NP CH ), electrochemical (Ag NP E ) and physical (Ag NP P ) methods. They were characterized by transmission electron microscopy and UV–Vis spectroscopy. Ag NPs were grafted onto plasma treated PET using dithiol interlayer because of Ag high affinity to thiol groups. Success of grafting was determined by X–ray photoelectron and energy dispersive X-ray spectroscopies. Atomic force and scanning electron microscopes also showed presence of both thiol and Ag NPs on plasma treated PET. Prepared samples were subjected to anti- bacterial tests against Escherichia coli and Staphylococcus epidermidis. Ag NP E were the smallest and their amount grafted onto PET surface was the highest. Therefore, PET with Ag NP E would be expected to have the best antibacterial effect. However, the highest antibacterial activity (for both strains) turned out to be on PET grafted with Ag NP P because far greater NP amount was situated more in the volume of grafted layer than on PET surface itself. 1. Introduction Polymer materials are irreplaceable part of our life for a long time owing to their physical-chemical properties, diverse chemical compo- sition and easy processing. Despite that, pristine polymers usually do not possess characteristics required for applications and have to be subjected to surface treatment. Diverse methods of surface modification are employed (e.g. UV-irradiation, plasma treatment, grafting) [1,2]. Among them, plasma treatment is one of the most popular. This tech- nique is easy to execute and do not produce toxic waste. Plasma dis- charge cause cleavage of polymer chains in thin surface layer of ma- terial. During the process, radicals and oxygen functional groups are formed, too. On top of that, physico-chemical characteristics like sur- face roughness and wettability can be easily adjusted by using different type of plasma [1,3,4]. Polymer materials became important materials utilised in medical field, particularly biocompatible polymers, as medical devices used outside, but also inside the body [1,5,6]. The application of these polymers is however hindered by their susceptibility to bacterial at- tachment and consequent biofilm formation, especially if they are used for longer period. This problem can lead to nosocomial infections that are difficult to treat. On top of that, higher bacterial resistance is a result of the frequent use of antibiotics (resistance acquired from evo- lutionary processes) and biofilm formation, which is onerous to remove. Bacteria within biofilms are surrounded by extracellular matrix, which add to their resistivity [7–10]. Effective prevention of bacterial con- tamination is to use antibacterial polymers. Some polymers have anti- bacterial properties on their own but antimicrobial polymers are also fabricated via proper modification - introducing bactericidal agents into their structure or in form of surface coatings [7,11,12]. Bactericidal polymers usually work on the principle of releasing antimicrobial substances from their surface or kill bacteria in contact with the surface. They are prepared by incorporating antibacterial agents into their structure, such as cationic biocides, antibacterial peptides, antibiotics etc. [8,9]. Prospective approach is polymers with metallic particles. Metals, https://doi.org/10.1016/j.reactfunctpolym.2019.104376 Received 30 July 2019; Received in revised form 30 September 2019; Accepted 2 October 2019 ⁎ Corresponding author. E-mail address: nguyeng@vscht.cz (H.Y. Nguyenova). Reactive and Functional Polymers xxx (xxxx) xxxx 1381-5148/ © 2019 Elsevier B.V. All rights reserved. Please cite this article as: H.Y. Nguyenova, et al., Reactive and Functional Polymers, https://doi.org/10.1016/j.reactfunctpolym.2019.104376