Traumatic, tumoral, and infectious bone defects are common in clinics, and create a big burden on patient’s families and society. Calcium phosphate (CaP)-based biomaterials have superior properties and have been widely used for bone defect repair, due to their similarities to the inorganic components of human bones. The biological performance of CaPs, as a determining factor for their applications, are dependent on their physicochemical properties. Hydroxyapatite (HAP) as the most thermally stable crystalline phase of CaP is mostly used in the form of ceramics or composites scaffolds with polymers. Nanostructured CaPs with large surface areas are suitable for drug/gene delivery systems. Additionally, CaP scaffolds with hierarchical nano-/microstructures have demonstrated excellent ability in promoting bone regeneration. This review focuses on the relationships and interactions between the physicochemical/biological properties of CaP biomaterials and their species, sizes, and morphologies in bone regeneration, including synthesis strategies, structure control, biological behavior, and the mechanisms of CaP in promoting osteogenesis. This review will be helpful for scientists and engineers to further understand CaP-based biomaterials (CaPs), and be useful in developing new high-performance biomaterials for bone repair.

This review article aims to provide insight into the research status of the potassium‐sulfur (K‐S) system, feature the challenges facing this technology, and present possible research directions for the realization of its practical applications. We begin with an introduction to the fundamental electrochemistry of K‐S batteries and emphasize the distinctions between K‐S technology and the well‐established lithium‐sulfur (Li‐S) system. Then, we focus on the development of the materials involved in K‐S batteries in terms of cathodes, K anodes, and various electrolyte systems. Finally, we provide several possible research directions to make the K‐S system a reality, with the emphasis, from our point of view, on the attempts to construct practical parameters for K‐S batteries by adopting the critical metrics of the current Li‐S system. image

The pathological microenvironment in diabetic wounds is delineated by heightened inflammatory responses and persistent proinflammatory macrophage activity, which significantly hinders the wound healing process. Exogenous electrical stimulation (ES), by modulating the electric field distribution in wounds, has shown significant potential in treating inflammatory wounds. However, this approach relies on additional power sources and complex circuit designs. Here, a bionic neuro-immuno-regulatory (BNIR) system was proposed for reshaping the endogenous electric fields (EFs) through collecting ion flow. The BNIR system comprises microporous structure scaffolds and nanosheets, enabling swift biofluid collection and electrical signal transmission, with the ability to promote cell proliferation and migration and exhibit antioxidant properties. More importantly, the BNIR system induced the transition of M1 macrophages to M2 macrophages through neuro-immuno-regulatory. In diabetic rat skin wounds, the BNIR system significantly enhanced healing by simultaneously neuro-immuno-regulatory, promoting angiogenesis, scavenging ROS, and facilitating tissue remodeling. This work aims to advance the development of a bionic system for electrosensitive tissue repair.

The treatment of infected bone defects (IBDs) needs simultaneous elimination of infection and acceleration of bone regeneration. One mechanism that hinders the regeneration of IBDs is the iron competition between pathogens and host cells, leading to an iron deficient microenvironment that impairs the innate immune responses. In this work, an in situ modification strategy is proposed for printing iron‐active multifunctional scaffolds with iron homeostasis regulation ability for treating IBDs. As a proof‐of‐concept, ultralong hydroxyapatite (HA) nanowires are modified through in situ growth of a layer of iron gallate (FeGA) followed by incorporation in the poly(lactic‐co‐glycolic acid) (PLGA) matrix to print biomimetic PLGA based composite scaffolds containing FeGA modified HA nanowires (FeGA‐HA@PLGA). The photothermal effect of FeGA endows the scaffolds with excellent antibacterial activity. The released iron ions from the FeGA‐HA@PLGA help restore the iron homeostasis microenvironment, thereby promoting anti‐inflammatory, angiogenesis and osteogenic differentiation. The transcriptomic analysis shows that FeGA‐HA@PLGA scaffolds exert anti‐inflammatory and pro‐osteogenic differentiation by activating NF‐κB, MAPK and PI3K‐AKT signaling pathways. Animal experiments confirm the excellent bone repair performance of FeGA‐HA@PLGA scaffolds for IBDs, suggesting the promising prospect of iron homeostasis regulation therapy in future clinical applications.