Nanotechnology detects bacteria
A group of researchers at Texas A&M University has developed a nanotechnology to rapidly detect and identify bacteria. The researchers call their technique 'SEnsing of Phage-Triggered Ion Cascade', or SEPTIC.
The SEPTIC technique uses bacteriophages – viruses that attack bacteria. When a bacteriophage infects a bacterium, it punctures the wall of the cell in order to inject its genetic material. As a result, ions leak out of the host cell (about 100 million in total). This causes tiny fluctuations in the electric field around the bacterium.
The scientists use an extremely small container (a nanowell) and tiny electrodes to detect these microscopic electric-field fluctuations.
The key to specificity comes from the properties of the phage: they are very choosy about which bacteria they infect. The researchers tested the technique on three strains of E. coli bacteria, using three different phages. They had a 100 per cent success rate in detecting and identifying the bacteria.
The technique is also quick. Other methods for detecting bacteria often take hours or days to complete, as well as requiring complicated and expensive equipment, making them unsuitable for use in the field.
A method for rapidly and inexpensively detecting bacteria is needed. Given its fast response, high specificity and relatively low cost, SEPTIC could be invaluable in clinical, veterinary and agricultural practice, as well as in the current fight against bioterrorism.
The ultimate aim is to have a biochip containing hundreds of nanowells. Each nanowell covers a different phage and, if a particular bacterium is present, the corresponding nanowell will signal and identify the bacterium. This would be a pen-size 'biolab' that would be able to identify hundreds of bacteria within minutes.
The researchers reported their work in the Journal of Biological Physics and Chemistry in March 2005.