Antibacterial Activity of Plastics Coated with Silver-Doped Organic−Inorganic Hybrid Coatings Prepared by Sol−Gel Processes

• Published in: Biomacromolecules Vol. 8; no. 4; pp. 1246 - 1254
• Main Authors: Marini, M, De Niederhausern, S, Iseppi, R, Bondi, M, Sabia, C, Toselli, M, Pilati, F
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-04-2007
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Applied sciences; Composites; Escherichia coli - drug effects; Exact sciences and technology; Forms of application and semi-finished materials; Gels - chemistry; Membranes, Artificial; Microbial Sensitivity Tests; Organometallic Compounds - chemistry; Organometallic Compounds - pharmacology; Plastics - chemistry; Polyethylene Glycols - chemistry; Polyethylenes - chemistry; Polymer industry, paints, wood; Silicon - chemistry; Silicon Dioxide - chemistry; Silver - chemistry; Staphylococcus aureus - drug effects; Surface Properties; Technology of polymers; Time Factors; Biological properties; Hybrid material; Ethylene oxide copolymer; Experimental study; Silicon copolymer; Silica; Coated material; Bactericidal effect; Low density ethylene polymer; Waterproofness; Ion mobility; Sol gel process; Preparation; Concentration effect; Ethylene copolymer; Silver compound; Doped polymer; Silver ion; Spin-on coating; Polyvinyl chloride; Block copolymer
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm060721b

Silver-doped organic−inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol−gel process. They were applied as a thin layer (0.6−1.1 μm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic−inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic−inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37 °C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features.