The Effect of Halloysite Addition on the Material Properties of Chitosan–Halloysite Hydrogel Composites

This study developed chitosan-halloysite nanotube hydrogel composites as biodegradable drug delivery materials and evaluated how polymer concentration and halloysite loading affected morphology, degradation, swelling, mechanics, antibiotic release, antibacterial performance, and cytocompatibility. Chitosan was ionically crosslinked with tripolyphosphate and combined with undoped or gentamicin-loaded halloysite nanotubes in different ratios. SEM showed that higher chitosan concentrations improved hydrogel structural integrity, while halloysite addition increased surface roughness and, within a limited range, helped preserve bead shape. Lysozyme degradation studies showed that halloysite addition did not significantly alter biodegradation, whereas swelling data indicated that lower chitosan concentration produced less crosslinked, more highly swelling hydrogels. Drug-release testing showed that halloysite-enabled composites provided a more sustained gentamicin release profile than drug-loaded halloysite alone, and bacterial inhibition assays confirmed effective suppression of E. coli and S. aureus when gentamicin was incorporated. Live/dead imaging with pre-osteoblasts showed good cytocompatibility. Mechanically, halloysite improved tensile properties only within a narrow concentration window, with 1–2% halloysite giving the greatest reinforcement and higher halloysite contents leading to nanotube clustering and reduced mechanical performance.