Synergistic utilization of cost-effective glycerophosphate and biologically active zein for innovative minimally invasive smart thermo-responsive hydrogels for potential hard tissue engineering applications

Abstract

Skeletal defects are the second-leading cause of disability worldwide, prompting the development of smart solutions for treatment. Calcium glycerophosphate (Ca-GP), chitosan (CS), hydroxyapatite (HA), and zein (ZN) were used to fabricate these thermo-responsive hydrogels. Ca-GP, an economically viable and bioactive glycerophosphate source, remains relatively underexplored. Natural protein ZN and the gold standard bone regenerative biomaterial HA were incorporated as reinforcing agents. The resulting composite hydrogels (HGs) exhibit a sol phase at 4 °C-10 °C and transition to gels at body temperature within 4-6 min. Their good injectability and the ability to be easily shaped into complex structures further support their great potential as minimally invasive solutions for treatment. The addition of ZN significantly improved the mechanical and biological properties of the HGs. The highest ZN concentration resulted in the strongest mechanical strength, measuring 52.2 MPa at 40% strain. HGs exhibited optimal swelling and degradation rates. Scanning electron microscopy analysis supported their porous nature. In vitro cell culture assays and wound healing assays demonstrated their excellent biocompatibility and regenerative potential. Drug-loaded HGs exhibited up to 90% drug release and antibacterial activity. All these results support their promising potential to support the regeneration of skeletal defects in a minimally invasive manner.