The Candida albicans fungus exists naturally in the skin, mouth, the mucous membranes lining the digestive tract, and the respiratory and genitourinary systems. It can cause anything from simple mycosis of the skin to complicated cases of candidiasis. It is much more commonly found in patients suffering from immunodeficiency, tumours, diabetes and lymphomas, among other diseases. Conventional diagnostic techniques for candida require long analysis times and sometimes give rise to false positives and negatives.
However, as reported recently in the journal Sensors and Actuators B: Chemical the Nanosensors group from the Universidad Rovira i Virgili has created a biosensor, an electrical and biological device, which is able to selectively detect the Candida albicans yeast in very small quantities of only 50 cfu/ml (colony-forming units per millilitre).
The technique uses field-effect transistors (electronic devices that contain an electrode source and a draining electrode connected to a transducer) based on carbon nanotubes and with Candida albicans-
specific antibodies. The candida samples, which can be obtained from blood, serum or vaginal secretions, are placed directly on the biosensor, where the interaction between antigens and antibodies changes the electric current of the devices. This change is recorded and makes it possible to measure the amount of yeast present in a sample.
Thanks to the extraordinary charge transference properties of the carbon nanotubes, the fungus detection process is direct, fast, and does not require the use of any marker. The new carbon nanotubes biosensor, will make it possible in future to obtain a rapid diagnosis of infection and allow early prophylactic intervention.
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First Published August 2009
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