New nanotube sensor can continuously monitor minute amounts ...( A new method that uses nanotechnolog...),Health

A new method that uses nanotechnology to rapidly measure minute amounts of insulin is a major step toward developing the ability to assess the health of the bodys insulin-producing cells in real time.

Among other potential applications, this method could be used to improve the efficacy of a new procedure for treating Type 1 (juvenile) diabetes that has demonstrated the ability to free diabetics from insulin injections for several years. It works by transplanting insulin-producing cells into the livers of diabetics to replace the cells that the disease has disabled or destroyed.

The new insulin detection method was developed by a team of Vanderbilt researchers headed by Associate Professor of Chemistry David Cliffel and is reported in the February 18 issue of the journal Analytica Chimica Acta.

To gain this capability, the researchers developed a new electrode for a device called a microphysiometer. The microphysiometer assesses the condition of living cells by placing them in liquid nutrient, confining them in a very small chamber and then measuring variations in their metabolism. The volume of the chamber is only three microliters about 1/20th the size of an ordinary raindrop allowing the electrode to detect the minute amounts of insulin released by special pancreatic cells called Islets of Langerhans.

The new electrode is built from multiwalled carbon nanotubes, which are like several flat sheets of carbon atoms stacked and rolled into very small tubes. Provided by William Hofmeister at the University of Tennessee Space Institute, the nanotubes are electrically conductive and the concentration of insulin in the chamber can be directly related to the current at the electrode and the nanotubes operate reliably at pH levels characteristic of living cells.

Current detection methods measure insulin production at intervals by periodically collecting small samples and measuring their insulin levels. The new sensor d
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