A freeze-thaw PVA hydrogel loaded with guava leaf extract: physical and antibacterial properties.

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity. This study succeeded in fabricating a PVA hydrogel containing GLE using the freeze-thaw (FT) method. By varying the GLE concentration, we can adjust the physical properties of the hydrogel. The addition of GLE results in a decrease in cross-linking during gelation and an increase in the pore size of the hydrogels. The increase of the pore size made the swelling increase and the mechanical strength decrease. The weight loss of the hydrogel also increases because the phosphate buffer saline (PBS) dissolves the GLE. Increasing the GLE concentration caused the Fourier-transform infrared (FTIR) absorbance peaks to widen due to hydrogen bonds formed during the FT process. The crystalline phase was transformed into an amorphous phase in the PVA/GLE hydrogel based on the X-ray diffraction (XRD) spectra. The differential scanning calorimetry (DSC) characterization showed a significant decrease in the hydrogel weight over temperatures of 30-150 °C due to the evaporation of water from the hydrogel matrix. The zone of inhibition of the PVA/GLE hydrogel increased with antibacterial activity against Staphylococcus aureus of 17.93% per gram and 15.79% per gram against Pseudomonas aeruginosa .