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The phase-field model was extended to simulate spinodal decomposition under the temperature gradient and external elastic strain in binary alloys, and the variations of phase decomposition temperature and precipitate morphology were investigated. In the system with a temperature gradient, the phase decomposition happens gradually from low temperature to high temperature. The strain energy induced by the applied strain promotes spinodal decomposition, and the morphology orientation is intensified with the increase of temperature and applied strain. The inhomogeneous microstructure is induced under the temperature gradient and applied strain along the temperature increment. Promoted by the composition inhomogeneity of the early precipitates and applied strain, the transition of the spinodal decomposition to nucleation and growth occurred in the high temperature regions.

An open critical-size bone defect is a major medical problem because of the difficulty in self-healing, leading to an increased risk of bacterial infection owing to wound exposure, resulting in treatment failure. Herein, a composite hydrogel was synthesized by chitosan, gallic acid, and hyaluronic acid, termed “CGH.” Hydroxyapatite was modified with polydopamine (PDA@HAP) and introduced to CGH to obtain a mussel-inspired mineralized hydrogel (CGH/PDA@HAP). The CGH/PDA@HAP hydrogel exhibited excellent mechanical performances, including self-healing and injectable properties. Owing to its three-dimensional porous structure and polydopamine modifications, the cellular affinity of the hydrogel was enhanced. When adding PDA@HAP into CGH, Ca2+ and PO43- could release and then promoted differentiation of BMSCs into osteoblasts. Without any osteogenic agent or stem cells, the area of new bone at the site of defect was enhanced and the newly formed bone had a dense trabecular structure after implanting of the CGH/PDA@HAP hydrogel for 4 and 8 weeks. Moreover, the growth of Staphylococcus aureus and Escherichia coli was effectively inhibited through the grafting of gallic acid onto chitosan. Above, this study provides a reasonable alternative strategy to manage open bone defects.

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