Bone tissue engineering is becoming an ideal strategy to replace autologous bone grafts for surgical bone repair, but the multihierarchical complexity of natural bone is still difficult to emulate due to the lack of suitable biomaterials. Supramolecular peptide nanofiber hydrogels (SPNHs) are emerging biomaterials because of their inherent biocompatibility, satisfied biodegradability, high purity, facile functionalization, and tunable mechanical properties. This review initially focuses on the multihierarchical fabrications by SPNHs to emulate natural bony extracellular matrix. Structurally, supramolecular peptides based on distinctive building blocks can assemble into nanofiber hydrogels, which can be used as nanomorphology-mimetic scaffolds for tissue engineering. Biochemically, bioactive motifs and bioactive factors can be covalently tethered or physically absorbed to SPNHs to endow various functions depending on physiological and pharmacological requirements. Mechanically, four strategies are summarized to optimize the biophysical microenvironment of SPNHs for bone regeneration. Furthermore, comprehensive applications about SPNHs for bone tissue engineering are reviewed. The biomaterials can be directly used in the form of injectable hydrogels or composite nanoscaffolds, or they can be used to construct engineered bone grafts by bioprinting or bioreactors. Finally, continuing challenges and outlook are discussed.

We report here a facile strategy to fabricate three-dimensional (3D) hydroxyapatite (HA) architectures with well-defined long continuous interconnected pores by using electrospinning and biomimetic mineralization. To this end, a polymeric nanofiber (NF) scaffold with well-defined architecture was fabricated by electrospinning, and bone morphogenetic protein 2 (BMP2) was then adsorbed onto the chemically modified NFs through bio-conjugation. The 3D nanoporous HA architecture was finally fabricated by biomimetic mineralization of the NF-BMP2 hybrid in simulated body fluids and subsequent dissolution of NFs in hexafluoroisopropanol. The formation of NF-BMP2 hybrid was identified by confocal laser scanning microscopy analysis. The crystal structure of HA crystals formed on NFs was examined by X-ray diffraction. The chemical composition and interconnected porous structure of the created 3D HA architectures were measured by X-ray photoelectron spectroscopy, focused ion beam scanning electron microscopy, and transmission electron microscopy, respectively. This bottom-up strategy based on electrospinning and biomimetic mineralization opens up a new way to prepare diverse porous HA-based hybrid materials and shows great potential in drug delivery, gene transfer and tissue engineering.

Bone grafting, as the current gold-standard for large scaled bone damage of various causes, has faced challenges from both the source and appliance. Emerging new tissue engineering substitutes are demonstrating more options and possibilities, with their improved biocompatibility, accessibility, and customizable function. Amongst them, injectable gels (IGs) are a class of gel material displaying astonishing non-invasive properties and surgical viability. While possessing responsiveness toward specific stimuli, they change their physical form in vivo, thus serving as wonderful biomaterials and drug delivery systems. In this review, the mechanics of stimuli-responsive IGs developed during the past decade are illustrated. Two branches of crosslinked gels -co-valent and non-covalent crosslinked IGs and their composition and customization are introduced. In conclusion, the present trend in bone tissue engineering research is summarized and made an outlook for future. It is hoped that this comprehensive review can provide a proper reference for the development of new IGs.

In article number 2000757, Xiaolin Wang and co‐workers make a breakthrough in the performance of ultra‐high thermoelectrics in p‐type bulk BiSbTe/Boron nanocomposite materials, which has great potential for wide application in solid‐state refrigeration and power generation.