# Investigation of Surface Properties and Antibacterial Activity of 3D-Printed Polyamide 12-Based Samples Coated by a Plasma SiOxCyHz Amorphous Thin Film Approved for Food Contact

## TL;DR

This paper explores a new food-safe coating for 3D-printed materials that strongly resists bacteria and biofilms, improving food safety and reducing the need for chemical cleaners.

## Contribution

The study introduces a plasma SiOxCyHz coating for 3D-printed PA12 that is approved for food contact and demonstrates strong antibacterial properties.

## Key findings

- Coated PA12 samples showed a high water contact angle of 112.9°, indicating strong hydrophobicity.
- The coating exhibited up to 99.99% bactericidal activity against key foodborne pathogens.
- The SiOxCyHz coating is suitable for mechanical components and packaging in food and pharmaceutical supply chains.

## Abstract

Microbial contamination and biofilm formation on food contact materials (FCMs) represent critical challenges within the food supply chain, compromising food safety and quality while increasing the risk of foodborne illnesses. Traditional materials often lack sufficient microbial resistance to contamination, creating a high demand for innovative antimicrobial surfaces. This study assessed the effectiveness of a nanosized deposited SiOxCyHz coating approved for food contact on 3D-printed polyamide 12 (PA12) disk substrates, aiming at providing antimicrobial and anti-biofilm functionality to mechanical components and packaging material in the food supply chain. The coating was applied using plasma-enhanced chemical vapor deposition (PECVD) and characterized through Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and contact angle measurements. Coated PA12 samples exhibited significantly enhanced hydrophobicity, with an average water contact angle of 112.9°, thus improving antibacterial performance by markedly reducing bacterial adhesion. Microbiological assays revealed a significant (p < 0.001) bactericidal activity (up to 4 logarithms after 4 h, ≥99.99%) against Gram-positive and Gram-negative bacteria, including notable foodborne pathogens such as L. monocytogenes, S. aureus, E. coli, and S. typhimurium. SiOxCyHz-coated PA12 surfaces exhibited strong antibacterial activity, representing a promising approach for coating additive-manufactured components and equipment for packaging production in the food and pharmaceutical supply chain able to enhance safety, extend product shelf life, and reduce reliance on chemical sanitizers.