Carp scales derived double cross-linking hydrogels achieve collagen peptides sustained-released for bone regeneration

Collagen peptide exhibits a great activity in osteogenic differentiation and wound healing. However, uncontrolled collagen peptide release in bone defects leads to unsatisfactory bone regeneration. In this work, we prepared collagen peptide loaded calcium alginate hydrogel (SA-CP/Ca) derived from Asia carp scales by mixing sodium alginate solution, collagen peptides, calcium carbonate, covalent cross-linking agents N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC), and N-hydroxysuccinimide (NHS) in one pot. Physically and chemically double cross-linking realized higher crosslink density, smaller porosity and pore size, and higher energy storage modulus and loss modulus, achieving sustained release of collagen peptides. The release profile is fitted to Keppas-Sahlin model, to find SA-CP/Ca hydrogels are more inclined to release collagen peptides through expansion and degradation. The compatibility and osteogenic ability of SA-CP/Ca are demonstrated in vitro and in vivo.