Micro/nanostructured calcium phytate coating on titanium fabricated by chemical conversion deposition for biomedical application.

A bioactive micro/nanostructured calcium phytate coating was successfully prepared on titanium surfaces by chemical conversion deposition, mainly through hydrothermal treatment of a mixed solution of phytic acid and saturated calcium hydroxide solution. Ultraviolet radiation was carried out to improve the adhesion of the coating to the titanium substrate. Pure titanium with a sandblasted/acid-etched surface was used as the control group. The topography and chemical composition of the modified surfaces were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and static water contact angle measurement. A pull-off test was performed to measure the coating-to-substrate adhesion strength. Bovine serum albumin was used as a model to study the protein adsorption effect. Cells were cultured on titanium surfaces for 7 days in osteogenic differentiation medium, then the osteoblast compatibility in vitro were explored by alkaline phosphatase and alizarin red staining. After 1, 2, 4 and 8 wks of immediate implantation of titanium implants into the mandibles of New Zealand white rabbits, biological effects in vivo were researched by microcomputed tomography analysis and histological evaluation. The results indicated that the roughness and hydrophilicity of the modified surfaces with micro/nanostructure remarkably increased compared to those of the control group. The pull-off test showed the average adhesion strength at the coating-substrate interface to be higher than 13.56 ± 1.71 MPa. In addition, approximately 4.41 mg/L calcium ion was released from the calcium phytate micro/nano coatings to the local environment after 48 h of immersion. More importantly, the micro/nanostructure titanium substrates significantly promoted cellular differentiation in vitro and in vivo. After 8 wks, the bone implant contact ratio (BIC, %) of the modified implants was higher than that of the control group, at 94.09 ± 0.55% and 86.18 ± 1.99% (p < 0.05). Overall, this study provided new insights into the factors promoting early osseointegration of titanium alloys, which had great potential not only for dental implants but also for various other biomaterial applications.

Periostin reverses high glucose-inhibited osteogenesis of periodontal ligament stem cells via AKT pathway.

AIMS: Diabetes mellitus leads to impaired osteogenic differentiation and alveolar bone absorption. Periostin (POSTN) is important for bone and tooth maintenance. This study aims to elucidate the expression of POSTN in high glucose and the effects of both high glucose and POSTN on osteogenesis in hPDLSCs, as well as the underlying mechanism. MAIN METHODS: Cells were incubated with glucose under physiological (5.5 mM normal glucose) or diabetic (30 mM high glucose) conditions in the presence or absence of recombinant human POSTN (rPOSTN). Cell migration was assessed by a scratch assay. Reactive oxygen species (ROS) was used to assess HG-induced oxidative damage. Osteogenesis was evaluated by alkaline phosphatase (ALP) activity and ALP staining, Alizarin Red staining (ARS), as well osteogenic related genes and proteins. KEY FINDINGS: POSTN expression was inhibited during a long-term culture with HG. HG diminished the migration and osteogenesis of hPDLSCs as indicated by decreases in ALP activity and ALP staining, ARS and expression of COL I, RUNX2, OSX, OPN and OCN, but an increase in reactive oxygen species overproduction. All of which were reversed by addition of rPOSTN. POSTN knockdown suppressed migration and osteogenesis of hPDLSCs. Moreover, HG inhibited activation of AKT, which was rescued by addition of POSTN. AKT inhibitor significantly reduced POSTN-mediated osteogenic differentiation. SIGNIFICANCE: rPOSTN could be a therapeutic regime for defective periodontal and peri-implant bone regeneration in diabetes mellitus.

Redox/pH dual-controlled release of chlorhexidine and silver ions from biodegradable mesoporous silica nanoparticles against oral biofilms.

BACKGROUND: Oral plaque biofilms pose a threat to periodontal health and are challenging to eradicate. There is a growing belief that a combination of silver nanoparticles and chlorhexidine (CHX) is a promising strategy against oral biofilms. PURPOSE: To overcome the side effects of this strategy and to exert maximum efficiency, we fabricated biodegradable disulfide-bridged mesoporous silica nanoparticles (MSNs) to co-deliver silver nanoparticles and CHX for biofilm inhibition. MATERIALS AND METHODS: CHX-loaded, silver-decorated mesoporous silica nanoparticles (Ag-MSNs@CHX) were fabricated after CHX loading, and the pH- and glutathione-responsive release profiles of CHX and silver ions along with their mechanism of degradation were systematically investigated. Then, the efficacy of Ag-MSNs@CHX against Streptococcus mutans and its biofilm was comprehensively assessed by determining the minimum inhibitory concentration, minimum bactericidal concentration, minimal biofilm inhibitory concentration, and the inhibitory effect on S. mutans biofilm formation. In addition, the biosafety of nanocarriers was evaluated by oral epithelial cells and a mouse model. RESULTS: The obtained Ag-MSNs@CHX possessed redox/pH-responsive release properties of CHX and silver ions, which may be attributed to the redox-triggered matrix degradation mechanism of exposure to biofilm-mimetic microenvironments. Ag-MSNs@CHX displayed dose-dependent antibacterial activity against planktonic and clone formation of S. mutans. Importantly, Ag-MSNs@CHX had an increased and long-term ability to restrict the growth of S. mutans biofilms compared to free CHX. Moreover, Ag-MSNs@CHX showed less cytotoxicity to oral epithelial cells, whereas orally administered Ag-MSNs exhibited no obvious toxic effects in mice. CONCLUSION: Our findings constitute a highly effective and safe strategy against biofilms that has a good potential as an oral biofilm therapy.