Coating Surfaces with Antimicrobial Thin Films Using Different Metal Nanoparticles and Their Characterization

Project no. 27362 · Status: Kapanmış · 2023

Summary

This study aimed to evaluate the hygienic status of food-contact surfaces and develop next-generation antimicrobial materials. Swab samples were collected from refrigerator surfaces in households and various food industry surfaces. It was determined that 88.89% of refrigerator surfaces and 20.59% of industrial surfaces met hygienic standards, while the remaining surfaces demonstrated inadequacies in hygiene practices. Among the bacterial isolates obtained, 79.49% were Gram-positive, 20.51% were Gram-negative, 84.62% were catalase-positive, and 61.54% were oxidase-positive. Biofilm formation capacity was weak in 65.81% of isolates but strong in 29.92%. Phenotypic and genetic analyses revealed that 20 selected bacterial isolates belonged to the genera Bacillus, Exiguobacterium, Rothia, Kocuria, Staphylococcus, Acinetobacter, Epilithonimonas, and Pseudomonas, while two yeast isolates were identified as Rhodotorula mucilaginosaand Candida parapsilosis. The antimicrobial effects of boron (B), aluminum (Al), and silicon (Si) nanoparticles (NPs) were evaluated against reference strains and wild-type strains isolated in this study, including bacteria, yeasts, and molds. Their cytotoxicity was assessed using human intestinal epithelial (Caco-2) and human skin fibroblast (BJ) cells. Al NPs exhibited higher antimicrobial activity against bacterial species compared to B and Si NPs, but none of the nanoparticles showed antifungal activity at tested concentrations. Toxicity studies identified IC50 values for BJ cells as B (93.3 µg/mL), Al (242.5 µg/mL), and Si (1259.2 µg/mL); for Caco-2 cells, only B NPs showed toxicity (IC50: 77.9 µg/mL). To develop antimicrobial surfaces, metal alloy (MA) thin films were synthesized using the TVA system and coated on HDPE, glass, and aluminum substrates. The MA films achieved bacterial inhibition rates up to 99.9% but were ineffective against molds. SEM, EDX, XRD, XPS, and AFM analyses confirmed homogeneous coating and elemental characteristics of the films. Migration tests revealed that MA coatings released boron, aluminum, and silicon into food simulants at levels well below regulatory limits over 10 days of storage. These findings demonstrate the safety and efficacy of MA-coated surfaces for food-contact applications.

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