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PubMed2006

Size-controllable fabrication of noble metal nanonets using a TiO2 template.

We present herein a simple template method for preparing noble metal nanonets with defined sizes. The template utilized is a TiO2 nanotube (NT) array prepared by anodic oxidation of a pure titanium sheet in an electrolyte solution containing sodium fluoride. Uniform NTs with defined sizes are obtained by controlling the anodic potential. Gold nanonets are prepared by electrodepositing gold onto the template and then dissolving the TiO2 template in a 0.2 M HF solution. The pore size of the gold nanonet is determined by the TiO2 NT hole size. The formation mechanism of the nanonet is elucidated from field-emission scanning electron microscopy and transmission electron microscopy. Although a lot of reports have been presented on the synthesis of nanostructure materials, no work has been reported on the template synthesis of gold nanonets. This paper gives a simple and universal way to prepare noble metal nanonets.

Chemistry, Inorganic↗

PubMed2004

A wireless, remote query glucose biosensor based on a pH-sensitive polymer.

This paper describes a wireless, remote query glucose biosensor using a ribbonlike, mass-sensitive magnetoelastic sensor as the transducer. The glucose biosensor is fabricated by first coating the magnetoelastic sensor with a pH-sensitive polymer and upon it a layer of glucose oxidase (GOx). The pH-responsive polymer swells or shrinks, thereby changing mass, respectively, in response to increasing or decreasing pH values. The GOx-catalyzed oxidation of glucose produces gluconic acid, inducing the pH-responsive polymer to shrink, which in turn decreases the polymer mass. In response to a time-varying magnetic field, a magnetoelastic sensor mechanically vibrates at a characteristic resonance frequency, the value of which inversely depends on sensor mass loading. As the magnetoelastic films are magnetostrictive, the vibrations launch magnetic flux that can be remotely detected using a pickup coil. Hence, changes in the resonance frequency of a passive magnetoelastic transducer are detected on a remote query basis, without the use of physical connections to the sensors.The sensitivity of the glucose biosensors decreases with increasing ionic strength; at physiological salt concentrations, 0.6 mmol/L of glucose can be measured. At glucose concentrations of 1-10 mmol/L, the biosensor response is reversible and linear, with the detection limit of 0.6 mmol/L corresponding to an error in resonance frequency determination of 20 Hz. Since no physical connections between the sensor and the monitoring instrument are required, this sensor can potentially be applied to in vivo and in situ measurement of glucose concentrations.

Acrylates↗