Sustainable biopolymer nanocomposite kappa Carrageenan/chitosan/hydroxyapatite hybrid nanofillers with efficient UV-shielding and biological activity

The growing concern regarding exposure to harmful ultraviolet (UV) radiation has attracted the development of biopolymer-based UV-blocking films. The study aims to prepare kappa-Carrageenan (kC)- based biopolymer nanocomposite films by incorporating Chitosan (CN) and hydroxyapatite (HA) nanoparticles. The influence of hydroxyapatite nanoparticles on the physicochemical characteristics of the polymer films was examined using analytical characterisation techniques. Changes in the polymers amorphous structure due to nanoparticle impregnation were studied by XRD, supported by significant changes observed in surface analysis using SEM. The UV-Vis spectral analysis showed improved optical performance with the incorporation of HA nanoparticles. The kC/CN film incorporated with 1 wt% of HA showed a significant reduction in both the direct band gap of 3.0 eV and the indirect band gap of 2.9 eV compared to plain kC/CN films. The biodegradability test showed a reduction in degradation rate after the addition of HA nanoparticles due to water uptake. All the films tested showed good antibacterial and antioxidant activity. Overall, the results suggest that the kC/CN/HA (1 wt%) nanocomposite film exhibits good optical and antibacterial properties. Hence, they possess significant potential for applications in UV shielding, face masks, and biomedical applications.