Siloxane functionalized phosphorylcholine (PC) or sulfobetaine (SB) macromolecules (PCSSi or SBSSi) were synthesized to act as surface modifying agents for degradable metallic surfaces to improve acute blood compatibility and slow initial corrosion rates. The macromolecules were synthesized using a thiol-ene radical photopolymerization technique and then utilized to modify magnesium (Mg) alloy (AZ31) surfaces via an anhydrous phase deposition of the silane functional groups. X-ray photoelectron spectroscopy surface analysis results indicated successful surface modification based on increased nitrogen and phosphorus or sulfur composition on the modified surfaces relative to unmodified AZ31. In vitro acute thrombogenicity assessment after ovine blood contact with the PCSSi and SBSSi modified surfaces showed a significant decrease in platelet deposition and bulk phase platelet activation compared with the control alloy surfaces. Potentiodynamic polarization and electrochemical impedance spectroscopy data obtained from electrochemical corrosion testing demonstrated increased corrosion resistance for PCSSi and SBSSi modified AZ31 versus unmodified surfaces. The developed coating technique using PCSSi or SBSSi showed promise in acutely reducing both the corrosion and thrombotic processes, which would be attractive for application to blood contacting devices, such as vascular stents, made from degradable Mg alloys.

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Highly aligned multi-wall carbon nanotubes were synthesized in the shape of towers and embedded into fluidic channels as electrodes for impedance measurement of LNCaP human prostate cancer cells. Tower electrodes up to 8 mm high were grown and easily peeled off a silicon substrate. The nanotube electrodes were then successfully soldered onto patterned printed circuit boards and cast into epoxy under pressure. After polishing the top of the tower electrodes, RF plasma was used to enhance the electrocatalytic effect by removing excess epoxy and activating the open end of the nanotubes. Electrodeposition of Au particles on the plasma-treated tower electrodes was done at a controlled density. Finally, the nanotube electrodes were embedded into a polydimethylsiloxane (PDMS) channel and electrochemical impedance spectroscopy was carried out with different conditions. Preliminary electrochemical impedance spectroscopy results using deionized water, buffer solution, and LNCaP prostate cancer cells showed that nanotube electrodes can distinguish the different solutions and could be used in future cell-based biosensor development.

This study was conducted to investigate the biocompatibility of Mg-Zn-Ca ternary alloy as a biodegradable material. The casting alloy underwent anodization in an alkaline electrolyte at current density 300 mA/cm(2) and frequency 50 Hz to obtain porous oxide layer. Plasma anodization film using pulse was shown to form irregular porous oxide film. As a result of corrosion test, the corrosion current was shown to decrease and the corrosion voltage was shown to increase in the anodized group, which showed the improvement of corrosion resistance after surface treatment. Sodium silicate (0.1 M) was directly oxidized due to high charges caused by spark and then formed SiO(2), and the compounds produced inside the film were shown MgO, Mg(2) SiO(4), and SiO(2.) In the histological examination in rats, all samples of the untreated group were shown to be absorbed 3 weeks later into the body. After the magnesium alloy was implanted, blood vessel expansion and tissue change were shown in the adjacent tissues. However, the changed tissues were shown to return to normal muscle tissues 4 weeks later when the alloy was completely absorbed. These results suggest that anodized Mg-35Zn-3Ca alloy has good biocompatibility in vivo and controls the absorption rate of biomaterials.

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