Bactericidal Effectiveness of 3D Printed PLA Surfaces Coated with Sealant Containing Silver Nitrate

Abstract This research characterized the morphological and chemical characteristics, as well as the biocidal effectiveness of polylactic acid (PLA) plate surfaces, created through additive manufacturing, both with and without an additional sealing coating of a polymer infused with silver nitrate crystals. In acknowledgement of the well-accepted principle of silver-based materials as antibacterial agents, this study delves deeper into the underlying mechanism responsible for the bactericidal effect of the sealant, offering a thorough characterization of the system and its behavior. To assess the bactericidal effect of the system, a suite of techniques including visual examination, optical microscopy (OM), digital image processing (DIP), scanning electron microscopy (SEM), semi-quantitative chemical analyses using energy dispersive spectroscopy (EDS), average roughness (Ra) computations, and in vitro tests were employed. The goal was to assess the impact of the presence or absence of the sealant on the proliferation of Escherichia coli American Type Culture Collection (ATCC) 11229 and Staphylococcus aureus ATCC 25923 bacteria. Results showed that the sealant had a significant antimicrobial effect, reducing the number of bacteria on the coated surfaces by at least 64 times within 30 minutes, in comparison with uncoated surfaces. This study also revealed the presence of micropores in the cross-section of the sealant layer. The microporous structure likely served as a conduit for silver ions from the encapsulated silver nitrate to exert their bactericidal effect on bacterial colonies. Whilst reinforcing the well-known bactericidal efficacy of silver, this investigation underscores the potential applicability of the proposed sealant in various fields requiring antimicrobial protection.