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The purpose of this research was to prepare gold nanorod- (GNR-) grafted TiO2 nanotubes by thiolactic acid treatment and evaluate remote-controlled drug elution and antibacterial activity by infrared (IR) light irradiation. Tetracycline used as an antibiotic was loaded into GNR-grafted TiO2 nanotubes by using 2w/v% polylactic acid solutions. A near-IR laser (830 nm) was used for remotecontrolled IR light irradiation. Results of SEM, TEM, XRD, and EDX revealed that GNR chemically bonded to the whole surface of the TiO2 nanotubes. An antibiotic release test revealed that on-off drug elution was triggered effectively by the photothermal effect of GNR grafted on TiO2 nanotubes. Furthermore, an antibacterial agar zone test indicated that the annihilated zone of Streptococcus mutans in the experimental group with IR light irradiation was significantly larger than that of the corresponding group without IR light irradiation (P < 0.05). Therefore, GNR-grafted TiO2 nanotubes would be expected to extend the limited usage of TiO2, which show photocatalytic activity only within the ultraviolet (UV) to IR region, thereby allowing the development of novel fusion technologies in the field of implant materials. [ABSTRACT FROM AUTHOR]

We cultured human mesenchymal stem cells (hMSCs) on TiO2 nanotubes with diameters of 30-100nm to assess the size-effect of TiO2 nanotubes on the behavior and osteogenic functionality of hMSCs. Most studies of the expression of genes encoding alkaline phosphatase (ALP), osteocalcin (OCN), osteopontin (OPN), and integrin-β (INT-B), after 1 week of incubation, supported the results of cell viability and MTT assays at 48 hrs of plating. However, after 2 weeks of incubation, expression of ALP, OPN, INT-B, and protein kinase R-like ER kinase (PERK) genes were significantly higher in cells cultured on 70nm TiO2 nanotubes than that in cells cultured on other TiO2 nanotubes and TiO. This biphasic osteogenic characteristic of hMSCs is supposed to relating to the nature of the hMSCs adhering to the substrate at the beginning of incubation, and the nanostructural stimulation caused by the topography of TiO2 nanotubes at a later stage of incubation. The discovery of these biphasic characteristics of hMSCs cultured on different-sized TiO2 nanotubes may contribute to resolving the discrepant results relating to the size-effect of TiO2 nanotubes on the adhesion, proliferation, and functionality of cells. [ABSTRACT FROM AUTHOR]

We have developed nitrogen-doped TiO2 nanotubes showing photocatalytic activity in the visible light region and have investigated the triggered release of antibiotics from these nanotubes in response to remote visible light irradiation. Scanning electron microscopy (SEM) observations indicated that the structure of TiO2 nanotubes was not destroyed on the conditions of 0.05 and 0.1 M diethanolamine treatment. The results of X-ray photoelectron spectroscopy (XPS) confirmed that nitrogen, in the forms of nitrite (NO2 -) and nitrogen monoxide (NO), had been incorporated into the TiO2 nanotube surface. A drug-release test revealed that the antibiotic-loaded TiO2 nanotubes showed sustained and prolonged drug elution with the help of polylactic acid. Visible light irradiation tests showed that the antibiotic release from nitrogen-doped TiO2 nanotubes was significantly higher than that from pure TiO2 nanotubes (P < 0.05). [ABSTRACT FROM AUTHOR]