The sensors can be applied to many different tasks, ranging from paternity tests and identifying people to detecting genetically modified food, identifying bacterial strains in foodborne illnesses and testing genetic toxicity in new drugs.
Salvador Alegret, Manuel del Valle and Maria Isabel Pividori, all of whom are members of the Sensors and Biosensors Group at the Independent University of Barcelona's Department of Chemistry (UAB), developed the new sensors based on their experience in research with electrochemical sensors.
To detect DNA, the new miniaturised electrochemical genosensors have a probe containing DNA fragments that complement the DNA they aim to detect. For example, to detect Salmonella in a sample of mayonnaise, the probe has fragments of the type of DNA that complements that found in a group of genes that identify the bacteria.
When the probe is submerged into the mayonnaise, some of the DNA fragments from the bacterial cells join the complementing fragments from the probe, creating a measurable electrical current. The sensor converts this current into a signal that can be seen by the person controlling the tests.
As the sensors are very small and easy to manipulate, it is possible to assemble a set of sensors that can collect data simultaneously and deduce information about the bacteria such as which strain caused the foodborne illness.
In trials developed with the support of the UAB's Department of Genetics and Microbiology, the new sensors have enabled Salmonella to be identified in four and a half hours, compared to three to five days using the traditional microbiological methods.
This method for identifying bacteria could also be used to detect other infectious agents such as Campylobacter and Listeria, and the sensor could easily be adapted for use in medicine, environmental monitoring and the industrial sector.
MEDICA.de; Source: Universitat Autònoma de Barcelona (UAB)