Preparation and Properties of Egg White Dual Cross-Linked Hydrogel with Potential Application for Bone Tissue Engineering

Abstract

In this study, an egg white dual cross-linked hydrogel was developed based on the principle that the external stimulus can denature proteins and cause them to aggregate, forming hydrogel. The sodium hydroxide was used to induce gelation of the egg white protein, subsequently introducing calcium ions to cross-link with protein chains, thereby producing a dual cross-linked hydrogel. The characteristics of the dual cross-linked hydrogels—including the secondary structure, stability, microstructure, swelling performance, texture properties, and biosafety—were investigated to determine the effects of calcium ion on the egg white hydrogel (EWG) and evaluate the potential application in the field of tissue engineering. Results showed that calcium ions could change the β-sheet content of the protein in EWG after soaking it in different concentrations of CaCl2 solution, leading to changes in the hydrogen bonds and the secondary structure of polypeptide chains. It was confirmed that calcium ions promoted the secondary cross-linking of the protein chain, which facilitated polypeptide folding and aggregation, resulting in enhanced stability of the egg white dual cross-linked hydrogel. Furthermore, the swelling capacity of the EWG decreased with increasing concentration of calcium ions, and the texture properties including hardness, cohesiveness and springiness of the hydrogels were improved. In addition, the calcium cross-linked EWG hydrogels exhibited biocompatibility and cell-surface adhesion in vitro. Hence, this work develops a versatile strategy to fabricate dual cross-linked protein hydrogel with biosafety and cell-surface adhesion, and both the strategy and calcium-egg white cross-linked hydrogels have potential for use in bone tissue engineering.

The Chicken Egg: An Advanced Material for Tissue Engineering

“…EW has also garnered interest in bone regeneration research; its biocompatibility and antibacterial characteristics significantly improve the performance of bone/dental biomaterials, especially in in vivo studies [52,54,[73][74][75]. Notably, Patty et al developed a nanocomposite with EW, where ovalbumin significantly affected the pore sizes and porosity of their bone biomaterials, and controllable pore sizes and porosity could be achieved by involving different concentrations of EW [73].…”

“…The study showed that cells grown on EW-Alginate (EWA) scaffold had comparable spheroid size to cells grown on Matrigel ® over 3 weeks. Similarly, Duan et al developed an EW dual crosslinked hydrogel with sodium hydroxide and CaCl 2 , and they found that increasing the concentration of calcium ions (from 0% to 4%) decreases the porosities of their hydrogels and the equilibrium swelling ratio [74].…”

Silk Fibroin Improves the Biological Properties of Egg White-Based Bioink for the Bioprinting of Tissue Engineering Materials

“…The nanoparticles exhibit excellent particle size dispersion, uniform morphology, effective drug release performance, favorable biocompatibility, and can effectively inhibit CT26 colorectal cancer cells in vitro In addition, the mechanical properties of EW materials also can be improved through cross-linking. With the addition of cross-linking agents such as methyl vinyl ether-maleic acid, carbodiimide, and glutaraldehyde, EW can form 3D scaffold materials with improved mechanical properties, which can promote cell adhesion and regeneration. − Duan et al used sodium hydroxide to induce the gelation of EW and subsequently introduced calcium ions to cross-link with EW protein chains to prepare a dual cross-linked hydrogel. This hydrogel exhibited biocompatibility and cell-surface adhesion in vitro and showed potential for use in bone tissue engineering.…”

“…With the addition of cross-linking agents such as methyl vinyl ether-maleic acid, carbodiimide, and glutaraldehyde, EW can form 3D scaffold materials with improved mechanical properties, which can promote cell adhesion and regeneration. 18 − 20 Duan et al 21 used sodium hydroxide to induce the gelation of EW and subsequently introduced calcium ions to cross-link with EW protein chains to prepare a dual cross-linked hydrogel. This hydrogel exhibited biocompatibility and cell-surface adhesion in vitro and showed potential for use in bone tissue engineering.…”