Photoreactivity and cell adhesiveness of amino-group-modified titanium dioxide nano-particles on silicone substrate coated by covalent linkage

Prevention of catheter infection using a biodegradable tissue adhesive composed of human serum albumin and disuccinimidyl tartrate

A new material was prepared to reduce catheter infection composed of a flocked silicone sheet (AmTiO2NP-F) with TiO2 nanoparticle–immobilized poly(ethylene terephthalate) fibers modified with surface amino groups. This system was used in conjunction with a tissue adhesive composed of disuccinimidyl tartrate and human serum albumin. At a fixed disuccinimidyl tartrate content of 0.2 mmol in human serum albumin solution, AmTiO2NP-F bonded well with collagen-based casing (a model material for skin), with bond strength increasing to a maximum of 38 w/v% human serum albumin. The adhesive bonded AmTiO2NP-F to subcutaneous tissue in mice, and infiltration of the tissue into the AmTiO2NP-F further increased the bond strength for long-term insertions. The material was degraded within 7 days of implantation, and tissue reaction was mild, while infection was completely prevented. These results indicate that the combined use of AmTiO2NP-F and disuccinimidyl tartrate-A for implanted catheters can significantly alleviate the associated risk of infection.

The in vitro inhibition of multidrug resistance by combined nanoparticulate titanium dioxide and UV irradition

The appearance of drug-resistant (especially, multidrug-resistant (MDR)) tumor cells is a major obstacle to the success of chemotherapy; thus, the development of effective anti-MDR agents plays an important role in the tumor therapy. In this report, the considerable effect of nano-TiO2 and UV illumination on the drug resistance of target cancer cells has been explored, and the fresh evidence from the fluorescence spectroscopy and microscopy as well as electrochemical studies demonstrates the significant enhancement effect of nano-TiO2 to the drug uptake by drug-resistant leukemia cells. Besides, it is also observed that the combination of the nano-TiO2 and UV irradiation with the accompanying anticancer drug daunorubicin could provoke some considerable changes of the cell membrane of the target leukemia cells, which indicates that nano-TiO2 could not only increase the drug accumulation in target cancer cells, but also act as an effective anti-MDR agent to inhibit the relative drug resistance.

Optimization of amino group density on surfaces of titanium dioxide nanoparticles covalently bonded to a silicone substrate for antibacterial and cell adhesion activities

A composite consisting of titanium dioxide (TiO2) particle, the surface of which was modified with amino groups, and a silicone substrate through covalent bonding at their interface was developed, and antibacterial and cell adhesion activities of the composite were evaluated. The density of the amino groups on the TiO2 particle surface was controlled by the reaction time of the modification reaction. The degradation rate of CH3CHO in the presence of the TiO2 particles under UV irradiation decreased with an increase in the amino group density on the TiO2 surface. On the other hand, the number of L929 cells adhering on the TiO2/silicone composite increased with an increase in the amino group density. From the above two results, the optimum density of amino groups for both photoreactivity and cell adhesiveness was estimated to be 2.0-4.0 molecules/nm2. The optimum amino group-modified TiO2/silicone composite sheet (amino group density, 3.0 molecules/nm2) showed an effective antibacterial activity for Escherichia coli bacteria under UV irradiation.