If the cap fits: Attachment of collagen (Col) to silica nanoparticles (MSN) by a disulfide linker, followed by introduction of lactobionic acid (LA, a cell‐specific targeting moiety), results in a redox‐responsive system for cell‐specific intracellular drug delivery and efficient endocytosis (see picture). Controlled release of a model drug (fluorescein isothiocyanate, FITC) was achieved by cleavage of the disufide bonds.

To investigate the influence of surface-functionalized substrates with nanostructures on the behaviors of mesenchymal stem cells, we conjugated bone morphogenetic protein 2 (BMP2) onto TiO(2) nanotubes with different diameter sizes of 30, 60, and 100 nm for in vitro study. Polydopamine was employed as the intermediate layer for the conjugation of BMP2. The successful conjugation of BMP2 onto TiO(2) nanotubes was revealed by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Immunofluorescence staining of vinculin, osteocalcin (OCN), and osteopontin (OPN) revealed that BMP2-functionalized TiO(2) nanotubes was favorable for cell growth. More importantly, MSCs cultured onto BMP2-functionalized TiO(2) nanotubes displayed significantly higher (p < 0.05 or p < 0.01) differentiation levels of ALP and mineralization after 7 and 14 day cultures, respectively. The results suggested that surface functionalization of TiO(2) nanotubes with BMP2 was beneficial for cell proliferation and differentiation. The approach presented here has potential application for the development of titanium-based implants for enhanced bone osseointegration.

Das Anbringen von Collagen (Col) an Siliciumoxid‐Nanopartikel (MSNs) über eine Disulfidbrücke und die anschließende Einführung von Lactobionsäure (LA) als zielführende Einheit ergaben ein redoxresponsives System für den zellspezifischen intrazellulären Wirkstoff‐Transport und die effiziente Endozytose (siehe Bild). Die kontrollierte Freisetzung des Modellwirkstoffs Fluoresceinisothiocyanat (FITC) gelang durch Spaltung der Disulfidbrücken.

The size‐mediated cytotoxicity of TiO2 nanoparticles is investigated at the cellular and molecular levels. The cytotoxicity dramatically increases around a particle size of 100 nm (nanoscale effect). This finding affords new insights into the cytotoxicity of nanomaterials, and has potential implications in the design of nanostructured biomaterials.

Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE s , are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

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Bone regeneration following injury is initiated by inflammatory signals and occurs in association with infiltration by sensory nerve fibers. Together, these events are believed to coordinate angiogenesis and tissue reprogramming, but the mechanism of coupling immune signals to reinnervation and osteogenesis is unknown. Here, we found that nerve growth factor (NGF) is expressed following cranial bone injury and signals via p75 in resident mesenchymal osteogenic precursors to affect their migration into the damaged tissue. Mice lacking Ngf in myeloid cells demonstrated reduced migration of osteogenic precursors to the injury site with consequently delayed bone healing. These features were phenocopied by mice lacking p75 in Pdgfra + osteoblast precursors. Single-cell transcriptomics identified mesenchymal subpopulations with potential roles in cell migration and immune response, altered in the context of p75 deletion. Together, these results identify the role of p75 signaling pathway in coordinating skeletal cell migration during early bone repair.

Surface topography of a biomaterial plays an essential role in the regulation of cell adhesion, proliferation, and differentiation. To investigate the influence of hierarchically micro/nano‐structured substrates on the differentiation of mesenchymal stem cells (MSCs), a series of micro‐, nano‐, and micro/nano‐structured titanium substrates were fabricated via dual acid etching and/or anodic oxidation. The morphologies of titanium substrates were characterized by field emission scanning electron microscopy (FE‐SEM) and contact angle measurement, respectively. The differentiation of MSCs adhered to different substrates was investigated in vitro. Compared to native titanium, micro/nano‐structured titanium substrates improved the alkaline phosphatase (ALP) production and mineralization of MSCs. More importantly, micro/nano‐structured titanium substrates demonstrated great potential to induce the differentiation of MSCs, which was revealed by the expressions of osteocalcin (OCN) and osteopontin (OPN). The study provides a potential alternative to generate hierarchically micro/nano‐structured titanium‐based implant for enhanced osseointegration.