Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Chitosan/gelatin hydrogels containing hydroxyapatite or hydroxyapatite/silver nanoparticles were developed and evaluated for bone tissue engineering applications, demonstrating biocompatibility and antimicrobial activity.

ABSTRACT
Bone tissue engineering demands multifunctional biomaterials capable of promoting regeneration while preventing local infections. In this study, hybrid chitosan/gelatin hydrogels crosslinked with L-arginine were developed by incorporating hydroxyapatite nanoparticles (HAp) in their pure form or modified with silver (HAp–Ag). HAp–Ag particles were synthesized with different silver nitrate concentrations (0.5%, 1.0%, and 2.0% w/w) and characterized in terms of morphology, crystallinity, cytocompatibility, and antimicrobial performance. The 2.0% silver formulation displayed the most pronounced antimicrobial effect against Gram-positive, Gram-negative, and fungal strains while maintaining cytocompatibility with L929 and MC3T3-E1 cells and was therefore selected for incorporation into the hydrogels. The resulting scaffolds presented highly porous structures (80%–89%) with interconnected pores, high water uptake (85%–125%), and low solubility (< 10% mass loss). Incorporation of nanoparticles reduced swelling and solubility while improving compressive strength in a concentration-dependent manner. Silver modification did not significantly alter the physicochemical performance of the hydrogels but provided antimicrobial functionality without impairing cytocompatibility or cell adhesion. Overall, the developed hydrogels combine mechanical reinforcement, biocompatibility, and antimicrobial activity, representing a promising platform for applications in bone regeneration, particularly in defects with high infection risk.