Konrad Kozlowski

Antibacterial coatings are needed to reduce surface contamination in clinical and textile environments, but many existing antimicrobial coatings rely on the release of biocides, creating concerns about toxicity and antimicrobial resistance, or require metal ions, harsh chemicals, and complex multi-step fabrication processes that limit practical deployment. In this study, six catechol aldehyde isomers were grafted onto bactericidal branched polyethylenimine (bPEI) using Schiff-base click chemistry to create one-component, metal-free coating solutions. Upon exposure to air and moisture, these solutions crosslinked into quinone-based networks that formed uniform films on cellulose substrates through simple dip-coating. Evaluation using colony-forming-unit counts, zone-of-inhibition assays, and ¹H NMR leachate analysis distinguished contact-killing activity from antibacterial effects caused by diffusion. All coatings exhibited low leaching, losing no more than 7.6% of their mass after aqueous exposure, while maintaining antibacterial performance after brief water and ethanol rinses. Notably, the bPEI-g-(3,5-DBA) formulation matched the strong contact-bactericidal activity of unmodified bPEI, achieving more than a three-log reduction in bacterial count. The results demonstrate that catechol substitution patterns can be used to control the balance between diffusible and surface-retained antibacterial activity, offering a versatile strategy for designing durable, wash-resistant, air-activated antibacterial coatings.

With the constant need for surface sterilization to prevent bacterial contamination, easily applied, non-leaching, wash resistant and contact-killing coatings that not include copper or silver ions are the ideal solution to the problem of inhibiting bacterial growth. Herein catechol coatings utilizing Schiff-base grafting to a polyethyleneimine matrix are evaluated for their contact inhibition against S.aureus and E.coli bacteria and their performance after water and ethanol washes, comparing zone of inhibition on agar plates and the toxicity of leachates from water submerged coatings.

Anaeorbic adhesives based on scaffolds of catechol isomers with Schiff-base grafting demonstrate activation upon aqueous immersion, showcasing variability beyond DOPA mimics.