Porous inorganic materials such as mesoporous silica nanoparticles (MSNs), mesoporous bioactive glasses (MBGs), porous calcium phosphates, and metal–organic frameworks (MOFs) are used for bone regeneration due to their osteoinductive and porous properties. The direct osteogenesis ability can be adjusted by the design and composition of those inorganic materials. With porous structure, adjustable pore size and high surface area, they are used as carriers to deliver various small molecular drugs, proteins, and genes locally to promote bone generation. The surface of those porous inorganic materials can be further functionalized to control the loading and release of drugs and modulate the behaviour of host cells. This review summarizes the recent advances of various porous inorganic nanomaterials for bone repairing with a focus on their performance as scaffolds and drug delivery systems. We also discuss the challenges and prospects of porous inorganic nanomaterials for the future clinical application for bone regeneration.

Biomaterial based scaffolds for treating large bone defects require excellent biocompatibility and osteoconductivity. Here we report on the fabrication of hydroxyapatite-dendritic mesoporous silica nanoparticles (HA-DMSN) based scaffolds with hierarchical micro-pores (5 µm) and nano-pores (6.4 nm), and their application for bone regeneration. The in vitro studies demonstrated good biocompatibility of dissolution extracts, as well as enhanced osteogenic potential indicated by dose-dependent upregulation of bone marker gene expression (osteocalcin gene (OCN), osteopontin gene (OPN), collagen type I alpha 1 gene (CoL1A1), runt-related transcription factor 2 gene (RUNX2), and integrin-binding sialoprotein gene (IBSP)), alkaline phosphatise (ALP) activity, and alizarin red staining. The in vivo studies showed that HA-DMSN scaffolds significantly increased bone formation in a rat cranial bone defect model after 4 weeks healing. Our study provides a simple method to fabricate promising inorganic scaffolds with hierarchical pores for bone tissue engineering.