Physicochemical and Microbiological Characterization of Chitosan and Agarose Hydrogel-Based Bioinks Functionalized with Dexamethasone for Wound Healing Applications

Abstract

This work evaluates agarose (AG)- and chitosan (CS)-based hydrogels incorporating a dexamethasone–cyclodextrin complex (Dex) as potential bioink candidates for wound healing applications. For this purpose, biopolymer hydrogels were formulated and tested to determine their structure, morphology, and rheological behavior under different strain, frequency, and temperature conditions, as well as their swelling behavior, surface functionality, protein adhesion capability, and antibacterial activity. Scanning electron microscopy revealed an interconnected membrane-like porous structure in the agarose/chitosan (BAC) hydrogels, which also showed a fibril-like microstructure when Dex was added. X-ray diffraction showed that these structures had a semicrystalline nature, with a main broad peak from approximately 15 to 20°. Rheological tests confirmed the viscoelastic behavior of the developed hydrogels. Chitosan incorporation reduced the rigidity of the formulations, whereas dexamethasone did not significantly affect the viscoelastic response of the BAC hydrogel. Additionally, the temperature sweep showed that Dex did not substantially alter the viscoelastic response of the BAC hydrogel while reducing mass loss after immersion in phosphate-buffered saline and not significantly affecting the swelling behavior. Further, Coomassie blue staining tests demonstrated favorable protein interaction with the BAC-based hydrogels, indicating that Dex incorporation did not compromise their adsorption capacity. Regarding their antibacterial activity, the hydrogels showed no major effects on Escherichia coli and Staphylococcus aureus in disk diffusion tests. However, liquid diffusion tests showed almost no bacterial growth for hydrogels incorporating CS. Thus, the present results demonstrate the potential of the BAC hydrogel system for biomedical and cosmetic applications.