ABSTRACT Bone defect healing is a dynamic process involving changes in the mechanical properties of the extracellular matrix (ECM), which significantly influence cellular behavior and tissue regeneration. In this study, we developed a dynamic stiffness hydrogel system designed to mimic the stiffness variation of the ECM during bone repair. The hydrogel, based on a 3D interpenetrating polymer network, enables in situ modulation of matrix stiffness by adjusting calcium ion concentrations through photothermal effects induced under near‐infrared (NIR) irradiation. The dynamic stiffness of the hydrogel was shown to support stem cell maintenance and promote osteogenic differentiation, aligning with the ECM characteristics observed in natural bone repair processes. Both in vitro and in vivo studies demonstrated that the mechanical cues provided by the hydrogel system significantly impact stem cell stemness and osteogenic potential. Furthermore, the hydrogel exhibited the ability to repair critical‐sized bone defects, underscoring its therapeutic potential. This work introduces a novel platform for bone tissue engineering, combining biomimicry and functional adaptability to optimize bone regeneration and laying the foundation for future clinical applications.
Yuxin Yang, Fan Yang, Lu Wang et al.· Advancement of science· 0 citations
Skin wounds are highly susceptible to bacterial invasion, and persistent infection remains a major obstacle to effective tissue repair. Conventional wound dressings often show insufficient antibacterial activity and limited capacity to actively regulate the infected wound microenvironment. Herein, an acid-responsive nanozyme-loaded composite fibrous membrane was developed as a non-antibiotic wound dressing for enhanced chemodynamic antibacterial therapy. Silver nanocubes were encapsulated within zeolitic imidazolate framework-67 to form Ag@ZIF-67 nanozymes, which were subsequently incorporated into electrospun polycaprolactone fibers to obtain Ag@ZIF-67/PCL composite membranes. Under weakly acidic conditions mimicking infected wounds, the ZIF-67 shell underwent microenvironment-triggered decomposition, enabling sustained release of Co2⁺ and Ag⁺. The released Co2⁺ catalyzed the conversion of H₂O₂ into highly toxic hydroxyl radicals through a Fenton-like reaction, while Ag⁺ provided additional broad-spectrum antibacterial activity. Benefiting from this complementary antibacterial mechanism and the extracellular matrix-like fibrous architecture, the Ag@ZIF-67/PCL membrane achieved antibacterial efficiencies exceeding 98% against both Escherichia coli and Staphylococcus aureus after 48 h. Moreover, the composite membrane exhibited favorable cytocompatibility and hemocompatibility, promoted endothelial cell migration, and significantly accelerated the healing of S. aureus-infected wounds in vivo by enhancing re-epithelialization, collagen deposition, and neovascularization. Overall, this study provides a pH-responsive, nanozyme-integrated fibrous membrane with combined antibacterial and pro-regenerative functions, offering a promising strategy for the treatment of bacteria-infected wounds without relying on antibiotics.
Han Lin, Jingyan Huang, Xiaoqi Xie et al.· Colloids and Surfaces B: Bio...· 0 citations