New biosensor can detect bacteria instantaneously

"We have developed a new biosensor that can detect extremely low concentrations of bacteria immediately, easily and reliably", said F. Xavier Rius, lead author of the study and a professor in the Chemometrics, Qualimetrics and Nanosensors research group in the Analytical Chemistry and Organic Chemistry Department of the URV.

Rius' team, jointly led by Jordi Riu, has come up with a technique that uses carbon nanotubes and synthetic DNA fragments that activate an electric signal when they link up with the pathogen. Described in a recent edition of the scientific journal Angewandte Chemie International Edition¹, it involves carbon nanotubes with inbuilt aptamers providing electrochemical readings.

The aptamers are small fragments of artificial DNA or RNA designed to attach themselves specifically to a particular molecule, cell or micro organism, in this case Salmonella. If the bacteria are not present, the aptamers remain on the walls of the carbon nanotubes. However, if they detect bacteria, they become activated and stick to it, and the carbon nanotubes generate an electric signal that is picked up by a simple potentiometer connected to the biosensor.

"The presence of the bacteria sparks a change in the interaction between the aptamers and the nanotubes, which takes place in a few seconds and creates an increase in the voltage of the electrode", says Rius.

Traditional methods for identifying and measuring micro-organisms require one or two days' analysis. "This technique means small quantities of micro-organisms can be detected simply and practically in real time, just the same as measuring the pH of water", adds the researcher.

Contact F. Xavier Rius. Departamento de Química Analítica y Química Orgánica. Universidad Rovira i Virgili, Tarragona, Spain T +34 977559562. fxavier.rius@urv.cat

Jordi Riu T +34 977558491 jordi.riu@urv.cat