P22 Fabrication methodologies for antimicrobial polypropylene surfaces with leachable and non-leachable antimicrobial agents

Abstract

Abstract Objectives Develop a methodology for the fabrication of antimicrobial polypropylene (PP) surfaces with (i) leachable copper (II) chloride dihydrate (CuCl2·2H2O) and (ii) non-leachable magnesium hydroxide (Mg (OH)2) biocides. Methods and results Two methodologies are used to develop antimicrobial PP surfaces. One method involves melt blending and subsequent injection moulding, where the biocide additives were compounded with PP and subsequently injection moulded. The other method involves the thermal embossing of antimicrobial agents on the surface of a PP substrate. The obtained biocide-bearing PP surfaces were evaluated against Escherichia coli K-12 MG1655 for 0, 4 and 24 h to evaluate their antimicrobial properties. The injection-moulded PP bearing 5% CuCl2·2H2O showed a 6-log reduction of E. coli K-12 MG1655 after 24 h, while only 1 log reduction was observed for PP bearing 5% Mg (OH)2. The thermally embossed PP surfaces bearing CuCl2·2H2O and Mg (OH)2 particles (at a concentration of 10 mg/mL) showed 3 log and 4 log reduction, respectively, against E. coli K-12 MG1655 after 24 h. Conclusions The results clearly demonstrate that CuCl2·2H2O conferred antimicrobial properties to PP surfaces that were prepared by both injection moulding and thermal embossing approaches owing to the presence of leachable copper ions. In contrast, the non-leachable Mg (OH)2 imparted antimicrobial properties only to the surface prepared via the thermal embossing technique. Significance and impact Plastics with leachable biocides are effective antimicrobial surfaces, but their toxicity is a major concern. This study provides a fabrication methodology for non-leachable PP-based antimicrobial surfaces that are potentially safer. In addition, this strategy can be extended to many other plastic substrates.