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Natural polymers and synthetic polymers have been extensively studied as scaffold materials, with the former offering advantages such as biocompatibility, biodegradability, and structural similarity to the natural extracellular matrix (ECM). However, the use of natural polymers in extrusion-based 3D printing has been limited by their poor mechanical properties and challenging rheological properties. In this study, gelatin and sodium alginate were utilized as scaffold materials, with the addition of Ca2+ and Mg2+ components to enhance their physical and chemical properties, and influence early cell behavior. Subsequently, these materials were fabricated into scaffolds using 3D printing. Our results demonstrated that the addition of Ca2+ and Mg2+ could improve the compactness of the 3D network structure, mechanical strength, swelling properties and degradation properties of methacrylated gelatin/methacrylated sodium alginate (GelMA/SAMA) composite hydrogel. In vitro cell tests revealed that the GelMA/SAMA composite hydrogel exhibited negligible cytotoxicity and promoted early cell viability, particularly with the higher concentration of Mg2+ in the material. Notably, the extrusion 3D printing process successfully produced GelMA/SAMA scaffolds. These results collectively indicate that GelMA/SAMA composite scaffolds hold promise as potential biomaterials for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Mineralized hydrogels have attracted significant attention in the field of bone repair. Herein, an innovative strategy of "freezing, salting‐out and mineralizing" (FSM) is proposed for the construction of mineralized hydrogels. Based on this strategy, a collagen/hydroxyapatite (HA) mineralized hydrogel is synthesized as the template of mineralized hydrogels, and the critical roles of freezing and salting‐out in the formation of hydrogels are demonstrated. Comparative analyses with collagen/HA mineralized hydrogels synthesized through two other traditional methods reveal that the hydrogel constructed by FSM exhibits satisfactory operation simplicity, mineralization degree, uniformity distribution, mechanical property, degradation stability, cytocompatibility, and osteogenic property, indicating that it can serve as an ideal mineralized hydrogel scaffold for bone repair. Furthermore, 16 other kinds of mineralized hydrogels with different systems are constructed by modularly expanding the raw materials used in the FSM process to nine common biomedical polymers, four metal cations and three anions, confirming the universality of the proposed FSM strategy for most mineralized hydrogel. Overall, the three‐step FSM strategy, which integrates the salting‐out effect with mineralization, represents a groundbreaking approach for the fabrication of mineralized hydrogels, offering a simple, universal and modular method for their construction. [ABSTRACT FROM AUTHOR]

Persistent oxidative stress and bacterial infection are significant challenges that impede diabetic wound healing. By combining diagnosis and treatment, pH variation on the wound tissue can be monitored in real time, and precise treatment can be carried out promptly to promote diabetic wound healing. In this study, a lipoic acid‐modified chitosa (LAMC) hydrogel is constructed via an amidation reaction, and ceria oxide‐molybdenum disulfide nanoparticles with a polydopamine layer (C@M@P), along with carbon quantum dots (CDs) synthesized by a hydrothermal method, are loaded into the hydrogel, thus developing a diagnostic and therapeutic hydrogel (LAMC/CD‐C@M@P). By incorporating CDs, the hydrogel exhibits high sensitivity and reversibility to pH under ultraviolet light. Furthermore, the images of hydrogels can be collected using smartphones and converted into wound pH signals, providing a means for early detection of bacterial infection. Notably, the LAMC/CD‐C@M@P hydrogel exhibits excellent photothermal antibacterial capability against Staphylococcus aureus and Escherichia coli and remarkable antioxidant and anti‐inflammatory abilities to alleviate reactive oxygen species and relieve inflammation response. In summary, this multifunctional hydrogel offers great potential as an innovative wound dressing platform, representing a significant advancement in chronic wound management. [ABSTRACT FROM AUTHOR]

Segmental bone defects, arising from factors such as trauma, tumor resection, and congenital malformations, present significant clinical challenges that often necessitate complex reconstruction strategies. Hydrogels loaded with multiple osteogenesis-promoting components have emerged as promising tools for bone defect repair. While the osteogenic potential of the Piezo1 agonist Yoda1 has been demonstrated previously, its hydrophobic nature poses challenges for effective loading onto hydrogel matrices.In this study, we address this challenge by employing Yoda1-pretreated bone marrow-derived mesenchymal stem cell (BMSCs) exosomes (Exo-Yoda1) alongside exosomes derived from BMSCs (Exo-MSC). Comparatively, Exo-Yoda1-treated BMSCs exhibited enhanced osteogenic capabilities compared to both control groups and Exo-MSC-treated counterparts. Notably, Exo-Yoda1-treated cells demonstrated similar functionality to Yoda1 itself. Transcriptome analysis revealed activation of osteogenesis-associated signaling pathways, indicating the potential transduction of Yoda1-mediated signals such as ErK, a finding validated in this study. Furthermore, we successfully integrated Exo-Yoda1 into gelatin methacryloyl (GelMA)/methacrylated sodium alginate (SAMA)/β-tricalcium phosphate (β-TCP) hydrogels. These Exo-Yoda1-loaded hydrogels demonstrated augmented osteogenesis in subcutaneous ectopic osteogenesis nude mice models and in rat skull bone defect model. In conclusion, our study introduces Exo-Yoda1-loaded GELMA/SAMA/β-TCP hydrogels as a promising approach to promoting osteogenesis. This innovative strategy holds significant promise for future widespread clinical applications in the realm of bone defect reconstruction. Highlights: • Exosomes derived from Yoda1 pretreated BMSCs promoted osteogenesis by transducing biological signals activated by Yoda1. • GELMA/SAMA/β-TCP hydrogels loading with Exo-Yoda1 was highly bio-compatibility and suitable for massive commercial application. [ABSTRACT FROM AUTHOR]

The healing of scalded wounds faces many challenges such as chronic inflammation, oxidative stress, wound infection, and difficulties in vascular and nerve regeneration. Treating a single problem cannot effectively coordinate the complex regenerative microenvironment of scalded wounds, limiting the healing and functional recovery of the skin. Therefore, there is a need to develop a multi-effect treatment plan that can adaptively address the issues at each stage of wound healing. In this study, we propose a scheme for on-demand release of hydrogen sulfide (H2S) based on the concentration of reactive oxygen species (ROS) in the wound microenvironment. This is achieved by encapsulating peroxythiocarbamate (PTCM) in the ROS-responsive polymer poly(ethylene glycol)–poly(L -methionine) (PMet) to form nanoparticles, which are loaded into a thermosensitive injectable hydrogel, F127-poly(L -aspartic acid-N-hydroxysuccinimide) (F127-P(Asp-NHS)), to create a scald dressing. The H2S released by the hydrogel dressing on demand regulates the wound microenvironment by alleviating infection, reducing oxidative stress, and remodeling inflammation, thereby accelerating the healing of full-thickness scalded wounds. This hydrogel dressing for the adaptive release of H2S has great potential in addressing complex scalded wounds associated with infection and chronic inflammation. [ABSTRACT FROM AUTHOR]