High effect of CO 2 laser and gamma irradiation on structural, thermal, and morphological properties of chitosan

A CO2 laser and gamma irradiation were used to alter chitosan, a biodegradable polysaccharide widely used in pharmaceutical and biomedical applications, to examine modifications in its surface, thermal, and structural characteristics. This study aimed to characterize and understand the structural, thermal, and morphological properties of chitosan induced by CO2 laser and gamma irradiation. Solutions of chitosan (2% wt v−1) were irradiated with CO2 laser (5 W for 5 and 10 s) and gamma radiation (0.1 mR h−1 for 5 and 10 days). While thermal analysis indicated only minor changes in stability, X-ray diffraction showed increased crystallinity in irradiated samples. The chitosan surface was smoothed by gamma irradiation, as observed by atomic force microscopy, whereas it became rougher after CO2 laser treatment due to thermal and cavitation effects. These surface changes imply that CO2 laser treatment can improve cell adhesion, which makes it advantageous for tissue engineering, while gamma irradiation is appropriate for uses like drug delivery. The new peaks observed after irradiation indicate enhanced crystalline ordering within the chitosan structure. Specifically, the XRD analysis showed additional peaks around 2θ = 10.25° and 20.9°, attributed to the (020) and (110) planes of semi-crystalline chitosan. These peaks suggest that both CO2 laser and gamma irradiation promote molecular chain alignment and structural reorganization, resulting in increased crystallinity of the chitosan films. The thermal degradation temperature (Td) and glass transition temperature (Tg) showed only minor changes according to thermogravimetric analysis (TGA), indicating that the irradiated chitosan had similar thermal stability. AFM revealed apparent changes in surface morphology.