New sensor detects cholera toxin

Hope for cholera sufferers in developing countries.

A team of US researchers has developed a new electrochemical biosensor that can detect the toxin secreted by Vibrio cholerae, the bacterium responsible for the spread of cholera. The sensor consists of 240 nm lipid microstructures that are adsorbed to the surface of a gold electrode. The lipids contain a ligand, ganglioside GM1, which is found in cell membranes and bound by the cholera toxin molecule. When this binding takes place, the microstructure’s normal electron transfer flow is interrupted and the change is sensed electrochemically.

Cholera is an extremely widespread disease. According to the World Health Organisation, its pandemic status extends from Asia, through Africa and the Middle East to Latin America. In developed countries, cholera’s main symptoms - diarrhoea and vomiting - are not serious. However, in an unprepared community with few treatment facilities the situation is much worse. The fast onset of severe dehydration can yield case-fatality rates as high as 50 per cent.

Quan Cheng, of the University of California, Riverside, who led the development of the new sensor, comments: ’There is a growing need for new analytical techniques capable of fast, sensitive and reliable detection of pathogenic agents’. He continues: ’one important development . is to fabricate electrochemical sensors with high sensitivity and low cost’.

Ian Farrell