Sustainable marine waste-derived hydroxyapatite/collagen/chitosan hydrogels as bioactive composite materials for bone-related applications

This study reports the development of a sustainable collagen type I/hydroxyapatite/chitosan (COL-1/HAp/CS) composite hydrogel as a bioactive material for bone-related applications. Hydroxyapatite synthesized from crab shell was incorporated into COL-1/chitosan matrices with various ratios to elucidate the ratio–property relationships. FTIR and XRD analyses confirmed successful crosslinking, strong organic–inorganic interactions, and preservation of crystalline hydroxyapatite with crystallinity ranging from 46.46 % to 89.77 %. The hydrogels exhibited ratio-dependent volumetric swelling ratio with equilibrium swelling reached within 2 h, ranging from 40 % to 145 %, reflecting differences in network hydrophilicity and structural flexibility. Mechanical testing showed enhanced performance, with a maximum compressive strength of 1.07 MPa and an elastic modulus of 5.50 MPa. Controlled degradation was observed in phosphate-buffered saline, with mass loss decreasing from ∼45 % to ∼25 % after 7d as chitosan ratio increased. SEM analysis revealed a ratio-dependent morphology from dense to porous networks, while in vitro bioactivity tests demonstrated apatite formation after 14d in simulated body fluid. Antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus was also confirmed. Overall, the COL-1/HAp/CS hydrogel with a 1/1/3 ratio exhibited a synergistic balance of mechanical performance, tunable degradation, bioactivity, and antibacterial properties, highlighting its potential as a sustainable bioactive composite hydrogel for bone-related applications.