An Injectable Hydrogel Composing Anti-Inflammatory and Osteogenic Therapy toward Bone Erosions Microenvironment Remodeling in Rheumatoid Arthritis

Zinc Oxide-Copper Sulfide Nanozyme Hydrogels for Bone Defect Repair by Modulating the Bone Immune Microenvironment and Promoting Osteogenesis/Angiogenesis

Bone defects caused by trauma, tumors, or infections pose significant challenges to clinical treatment because of the complex pathological microenvironment they create. Elevated levels of inflammatory factors and reactive oxygen species (ROS) at the defect site disrupt the bone immune microenvironment, impeding bone regeneration. Concurrently, the vascular damage frequently associated with bone defects leads to hypoxia, further complicating therapeutic efforts. Although bone grafting remains a primary clinical approach, its efficacy is limited by these adverse conditions. In this study, a ZnO-CuS/F127 nanozyme hydrogel with multiple enzymatic activities was manufactured for bone defect repair via the modulation of the bone immune microenvironment and the promotion of osteo-/angiogenesis, which was accomplished via the encapsulation of ZnO-CuS nanoflowers synthesized via calcination into the F127 hydrogel matrix. ZnO-CuS bimetallic nanoenzymes exhibit robust catalase (CAT) and superoxide dismutase-like activities, enabling effective scavenging of diverse ROS species in vitro. In cellular assays, ZnO-CuS/F127 protected bone marrow mesenchymal stem cells [bone mesenchymal stem cells (BMSCs)] from ROS-induced cytotoxicity and promoted macrophage polarization toward the anti-inflammatory M2 phenotype, thus modulating the bone immune microenvironment. The ZnO-CuS/F127 hydrogel demonstrated potent proangiogenic and pro-osteogenic effects, attributed to its ability to upregulate the Wnt/β-catenin signaling pathway while inhibiting the NF-κB pathway in BMSCs, as confirmed by RNA sequencing. In vivo, the hydrogel exhibited exceptional hemostatic performance and facilitated bone defect repair in mouse hemorrhage and rat bone defect models while maintaining high biocompatibility and low cytotoxicity. This study highlights the use of the ZnO-CuS/F127 nanozyme hydrogel as a promising therapeutic strategy for bone defect repair. By modulating the immune microenvironment and promoting angiogenesis and osteogenesis, this multifunctional hydrogel offers innovative insights and a potential clinical solution for addressing the multifaceted challenges of bone regeneration.

ROS-Activated Nanohydrogel Scaffolds with Multi-Factors Controlled Release for Targeted Dual-Lineage Repair of Osteochondral Defects

Achieving self-healing for osteochondral defects caused by trauma, aging, or disease remains a significant challenge in clinical practice. It is an effective therapeutic strategy to construct gradient-biomimetic biomaterials that replicate the hierarchical structure and complex microenvironment of osteochondral tissues for dual-lineage regeneration of both cartilage and subchondral bone. Herein, ROS-activated nanohydrogels composite bilayer scaffolds with multi-factors controlled release are rationally designed using the combination of 3D printing and gelatin placeholder methods. The resulting nanohydrogel scaffolds exhibit micro-nano interconnected porous bilayer structure and soft-hard complex mechanical strength for facilitating 3D culture of BMSCs in vitro. More importantly, multi-stage continuous responses of anti-inflammation, chondrogenesis and osteogenesis, are effectively induced via the sequential release of multi-factors, including diclofenac sodium (DS), kartogenin (KGN) and bone morphogenetic protein 2 (BMP-2), from ROS-activated nanohydrogel scaffolds, thereby improved dual-lineage regeneration of cartilage and subchondral bone tissue in the osteochondral defect model of SD rats. These findings suggest that ROS-activated nanohydrogel scaffolds with such specific soft-hard bilayer structure and sequential delivery of functional factors, provides a promising strategy in dual-lineage regeneration of osteochondral defects.

A Bacterial Capturing, Neural Network-Like Carbon Nanotubes/Prussian Blue/Puerarin Nanocomposite for Microwave Treatment of Staphylococcus Aureus-Infected Osteomyelitis

Staphylococcus aureus (S. aureus)-infected osteomyelitis is a deep tissue infection that cannot be effectively treated with antibiotics. Microwave (MW) thermal therapy (MTT) and MW dynamic therapy (MDT) based on MW-responsive materials are promising for the therapy of bacteria-infected osteomyelitis occurring in deep tissues that cannot be effectively treated with antibiotics. In this work, the MW-responsive system of carbon nanotubes (CNTs)/Prussian blue (PB)/puerarin (Pue) with stable network-like structures is constructed. The PB is grown in situ on the CNTs, and its introduction not only reduces the aggregation of the network-like structures of the CNTs, but the large specific surface area and mesoporous structure can also provide many active sites for the adsorption of oxygen and polar molecules. Pue is a natural anti-inflammatory material that reduces inflammation at the infection site. The composite of the CNTs and PB avoids the skin effect and thus can improve dielectric and reflection losses. The MW thermal response of CNTs/PB/Pue is mainly due to the occurrence of reflection loss, dielectric loss, multiple reflections and scattering, interface polarization, and dipole polarization. In addition, under MW irradiation, the CNTs/PB/Pue can produce reactive oxygen species (ROS), such as singlet oxygen (1O2), hydroxyl radical (·OH).

Interface/Dipole Polarized Antibiotics-Loaded Fe3O4/PB Nanoparticles for Non-Invasive Therapy of Osteomyelitis Under Medical Microwave Irradiation

Due to their poor light penetration, photothermal therapy and photodynamic therapy are ineffective in treating deep tissue infections, such as osteomyelitis caused by Staphylococcus aureus (S. aureus). Here, a microwave (MW)-responsive magnetic targeting composite system consisting of ferric oxide (Fe3O4)/Prussian blue (PB) nanoparticles, gentamicin (Gent), and biodegradable poly(lactic-co-glycolic acid) (PLGA) is reported. The PLGA/Fe3O4/PB/Gent complex is used in combination with MW thermal therapy (MTT), MW dynamic therapy (MDT), and chemotherapy (CT) to treat acute osteomyelitis infected with S. aureus-infected. The powerful antibacterial effect of the PLGA/Fe3O4/PB/Gent is determined by the synergistic effects of heat and reactive oxygen species (ROS) generation by the Fe3O4/PB nanoparticles under MW irradiation and the effective release of Gent at the infection site via magnetic targeting. The antibacterial mechanism of the PLGA/Fe3O4/PB/Gent under MW irradiation is analyzed using bacterial transcriptome RNA sequencing. The MW heat and ROS reduce the activity of the protein transporters on the bacterial membrane, along with the transport of various ions and the acceleration of phosphate metabolism, which can lead to increased permeability of the bacterial membrane, damage the ribosome and DNA, and accompany the internal protein efflux of the bacteria, thus effectively killing the bacteria.