# A Multifunctional Bioactive Nanoscale Coating Deposited by Atmospheric Pressure Plasma Polymerization of Peppermint Essential Oil

## TL;DR

A new coating made from peppermint oil using plasma polymerization can reduce infection and inflammation on medical devices like catheters.

## Contribution

A one-step atmospheric pressure plasma polymerization process converts peppermint essential oil into a stable, multifunctional bioactive coating.

## Key findings

- The coating scavenges up to 90% of reactive species and reduces pro-inflammatory cytokine expression by up to 60%.
- It promotes M2 macrophage polarization and exhibits intrinsic antibacterial activity, reducing viable bacteria by 90% (Live/Dead) and 70% (CFUs).
- The coating potentiates the activity of colistin and levofloxacin antibiotics used in catheter-associated urinary tract infection management.

## Abstract

Implanted and indwelling medical devices remain challenged by infection, oxidative stress, and chronic inflammation, underscoring the need for multifunctional surface coatings to holistically address these complications. Peppermint essential oil is inherently antibacterial, antioxidant, and anti‐inflammatory, yet its integration into stable, contact‐active coatings is limited by fabrication constraints. Here, we present a one‐step atmospheric pressure plasma polymerisation process that converts peppermint essential oil into a conformal, cross‐linked coating that preserves precursor‐derived functional groups that drive broad bioactivity. While the coating is substrate‐independent, we evaluate its bioactive performance within the context of bladder catheterisation as a pilot application. It scavenges up to 90% of reactive species, reduces pro‐inflammatory cytokine expression by up to 60%, and increases anti‐inflammatory cytokines by up to 50%, while promoting macrophage polarisation toward an M2 phenotype. The coating exhibits intrinsic antibacterial activity, reducing viable bacteria by 90% (Live/Dead) and 70% (CFUs), attributed to membrane disruption of Gram‐negative pathogens. In turn, this interaction potentiates the activity of colistin and levofloxacin, two antibiotics used in catheter‐associated urinary tract infection management. Together, these findings establish a stable, multifunctional coating capable of mitigating infection, alleviating inflammation, and enhancing antibiotic performance, while offering a sustainable route for essential‐oil‐derived biomaterials.

Atmospheric plasma polymerization transforms peppermint essential oil into ultrathin, substrate‐independent bioactive coatings with antioxidant, contact‐active antibacterial, and immunomodulatory functions. The coating disrupts Gram‐negative pathogens, potentiates prophylactic antibiotics, suppresses pro‐inflammatory signaling, and promotes M2 macrophage polarization. These sustainable, multifunctional films offer a promising strategy for improving outcomes of implantable medical devices, including urinary catheters.