Eco-friendly synthesis of ZnO nanoparticles for improved pectin/chitosan hydrogels with antibacterial activity

The core objective of the present study was to develop a novel nanocomposite pectin/chitosan hydrogel based on green-synthesised zinc oxide nanoparticles (ZnO NPs-L). For this purpose, zinc oxide nanoparticles were prepared by the solution casting method, using extract from aloe vera leaves, and were incorporated into pectin/chitosan hydrogels (0, 10, and 20%). The nanoparticles were analysed using scanning electron microscopy, X-ray diffraction, UV-Vis, and FTIR (Fourier transform infrared) spectroscopy. Moreover, the hydrogels were evaluated through FTIR, scanning electronic microscopy, atomic force microscopy, gel fraction, contact angle measurements, swelling ratio, investigations of thermal stability, mechanical strength and antibacterial activity. The structural heterogeneity and surface roughness of the hydrogel were evidenced by SEM analysis. The results showed that incorporation of ZnO NPs-L into hydrogel enhanced gel fraction to > 65%, surface wettability to > 64°, tensile strength to > 5.8 MPa, and swelling ratio to > 4 140 in a dose-dependent manner. Further, ZnO NPs-L (20 mg) loaded hydrogels exhibited the highest zone of inhibition against Escherichia coli (> 13 mm) and Staphylococcus aureus (> 12 mm). The findings suggested that pectin/chitosan/ZnO NPs-L hydrogels have appropriate mechanical flexibility, swelling behaviour and antibacterial activities, which are required for their effective use in the biomedical and agricultural sectors.