# Design and Characterization of PAA/CHI/Triclosan Multilayer Films with Long-Term Antibacterial Activity

## TL;DR

Researchers created a long-lasting antibacterial coating using chitosan, polyacrylic acid, and triclosan for biomedical uses.

## Contribution

A novel multilayer film with pH-responsive triclosan release and long-term antibacterial stability was developed.

## Key findings

- Coatings assembled at pH 5 showed strong antibacterial activity against S. aureus and E. coli.
- Antimicrobial properties and structural integrity were maintained over 40 days.
- Triclosan release was enhanced under acidic conditions (pH 5.5).

## Abstract

The development of antibacterial coatings for biomedical applications is crucial to prevent implant-associated infections (IAIs). In this study, we designed and evaluated a multilayer coating based on chitosan (CHI), polyacrylic acid (PAA), and triclosan (TCS) using the layer-by-layer (LbL) self-assembly technique. The successful incorporation of TCS was confirmed by Fourier-transform infrared (FTIR) spectroscopy. Surface roughness and topography were analyzed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Additionally, the pH-dependent behavior of PAA/CHI films was studied to assess its effect on TCS loading. According to disk diffusion assays, coatings assembled at pH 5 (PAA5/CHI5/TCS) exhibited the strongest antibacterial activity, with inhibition zones of 60.0 ± 0.0 mm for S. aureus and 33.67 ± 1.5 mm for E. coli. The long-term stability of the coatings was evaluated by measuring the antibacterial activity after 1, 10, 20, 30, and 40 days, with results confirming that antimicrobial properties and structural integrity were preserved over time. Furthermore, TCS release kinetics were assessed under physiological (pH 7.4) and acidic (pH 5.5) conditions, revealing enhanced release at pH 5.5. These findings highlight the potential of this multilayer system for biomedical applications requiring both stability and pH-responsive drug release.