Synthesis and physical–chemical characterization of chitosan grafted with hyaluronic acid as potential application in biomaterials

Chitosan (Chit) is a naturally derived polymer with significant potential for applications in medicine and pharmacology. Despite its biological activity, biocompatibility, cost-effectiveness, biodegradability, and low toxicity, Chit limited water solubility at pH < 6, restricts its use in biological fields, especially in medicine. To overcome this limitation, the study proposes the graphitization of Chit with hyaluronic acid (HA) (Chit-HA). The graphitization was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and Hydrogen Nuclear Magnetic Resonance Spectroscopy (¹H NMR) analysis. In this work the grafting yield percentage was 75.2%. Thermogravimetric Analysis (TGA) showed an increasing stage of mass loss for Chit-HA, attributed to the decomposition of HA in the Chit chain. Differential Scanning Calorimetry (DSC) revealed a new exothermic peak at 256.9 °C for Chit-HA, indicating the thermal degradation of HA grafted onto the Chit chain. Solubility assay demonstrated an increase in water solubility for Chit-HA compared to Chit. In contrast to the Chit sample, the Zeta Potential measurements of Chit-HA exhibited negative charge throughout the analyzed pH range. Therefore, the results confirm the successful grafting of Chit with HA, resulting in a new material with potential application in the biomedical field.