Synthesis and Characterization of Carrageenan/Polyaniline Film and Its Antibacterial Properties

In this study, polyaniline was synthesized as a potential antibacterial agent and integrated into κ‑carrageenan as a biopolymer matrix. Polyaniline samples were polymerized at 0°C and room temperature using a chemical oxidative method with hydrochloric acid as a dopant. Ex-situ polymerization was employed, incorporating polyaniline into κ-carrageenan with glycerol as a plasticizer to produce composite films. These films were characterized by FTIR, electrical conductivity, tensile test and TGA analyses. The addition of polyaniline enhanced the conductivity of pure κ-carrageenan film and improved its thermal stability, although mechanical properties such as tensile strength, modulus and elongation at break decreased. The antibacterial activity of the films was evaluated using an agar disc diffusion method against Gram-positive S. aureus and Gram-negative P. aeruginosa. Composite film demonstrated optimal antibacterial activity, achieving a 37.3 ± 2.2% against S. aureus after 24 h. The antibacterial mechanism was attributed to electrostatic interactions between cationic N⁺ from the quinoid structure of polyaniline and anionic bacterial membrane of S. aureus, causing disruption of the bacteria cell. Composite film retained antibacterial activity against S. aureus for up to 48 h. These findings suggest that produced composite films hold potential as wound dressings due to their antibacterial properties.