The URV develops a biosensor that can immediately detect the bacterium that causes typhoid fever

The research group in Chemometrics, Qualimetrics and Nanosensors has created a biosensor that immediately detects very low concentrations of Salmonella Typhi, the bacterium that causes typhoid fever. The technique uses carbon nanotubes and synthetic fragments of DNA that activate an electric signal when they link with the pathogen.
 

The research group, which is part of the Department of Analytical Chemistry and Organic Chemistry and led by professor Francesc Xavier Rius and the researcher Jordi Riu, has developed a technique for detecting extremely low concentrations of Salmonella Typhi.

Details of the new biosensor will be published in the September edition of the scientific journal Angewandte Chemie International Edition, and it works by taking electrochemical measurements using carbon nanotubes equipped with aptamers.

Aptamers are little fragments of artificial DNA or RNA that are made to stick to a specific molecule, cell or microrganism. If no bacteria are present, the aptamers remain on the walls of the carbon nanotubes, but if bacteria are detected, the aptamers are activated and join up with the bacteria. This causes the carbon nanotubes to generate an electric signal that is detected by a simple potentiometer connected to the biosensor.

The presence of the bacteria causes a change in the interaction between the aptamers and the nanotubes, and within seconds this increases the voltage of the electrode. The traditional methods for identifying and quantifying micro organisms take one to two days of analysis. With this technique, small quantities of micro-organisms can be detected simply and almost in real time, as is the case when testing the pH of water.

The study is part of international research into the most effective and quickest methods for detecting all sorts of pathogens. The new biosensor can detect a single salmonella cell in a five millilitre sample and can quantify up to 1,000 bacteria per millilitre.

For more information, contact tel. 0034 977 55 84 91 or jordi.riu@urv.cat