Effect of Citric Acid Concentration on the Properties of PVA/Bitter Gourd Composite Films for Potential Wound Dressing Applications

Abstract

Polymer-based films with suitable mechanical, thermal, and antibacterial characteristics are increasingly being explored for potential wound-dressing applications. This study investigated the effect of different citric acid (CA) concentrations (0, 1, 2.5, and 5 wt.%) on the structural, mechanical, thermal, and antibacterial properties of polyvinyl alcohol(PVA)/bitter gourd (BG) composite films. The films were prepared using the solution casting method. Fourier Transform Infrared (FTIR) spectroscopy showed slight changes in the O–H, C=O, and C–O absorption bands following CA incorporation, suggesting changes in intermolecular interactions within the PVA/BG matrix. The control film showed the highest tensile strength (8.47 ± 1.42 MPa), Young’s modulus (53.17 ± 6.96 MPa), and elongation at break (166.61 ± 51.43%). Among the films containing CA, the 2.5 wt.% CA formulation showed a better balance of tensile strength and Young’s modulus. Differential scanning calorimetry (DSC) showed changes in the melting and crystallization behaviour with increasing CA concentration, indicating that CA influenced the molecular arrangement within the PVA/BG matrix. Antibacterial evaluation of the film-forming solutions showed increasing inhibition against Bacillus subtilis with increasing CA concentration, with the 5 wt.% CA formulation producing the largest inhibition zone (10.67 ± 0.58 mm), whereas the differences against Escherichia coli were not statistically significant. Overall, the findings demonstrate that CA concentration influenced the properties of the PVA/BG formulations and provide useful information for their further development as potential wound-dressing materials. Further evaluation of the final films, particularly their antibacterial performance and other wound-dressing- related properties, is required to establish their suitability for practical applications.