Biosensors based on DNA aptamers for detection of bacterial pathogens in food

The bacterial pathogens are rather dangerous for the humans and animals. Therefore, food safety requires careful control of possible bacterial contamination at the farms of primary producents and industrial food plants. Conventional methods based on cultivation of bacteria are sensitive but are time consuming due to the necessity of bacteria cultivation and can be applied only in specialized laboratories. The powerful analytical methods such as high precision liquid chromatography (HPLC) gas chromatography, mass spectroscopy or enzyme-linked immunosorbent assay (ELISA) are sufficiently sensitive but require qualified staff and expensive instruments. As an alternative, biosensor technology is extensively developed for detection the bacterial pathogens on producer site without requirements of specialized laboratories. The current trends are in application of the nucleic acid aptamers a as receptors that can replace more expensive and less stable antibodies. This Chapter includes a brief overview of existing conventional methods of detection of bacteria, the mani focus is on the recent achievements in the development of aptamer-based biosensors. The aptamers, often referred to as chemical antibodies, are of increased interests due to their high specificity and stability, which is important for biosensor performance. Among nucleic acid aptamers the DNA aptamers are more often used in comparison with RNA aptamers because of their superior stability and lower cost. Considering the significant importance of aptamers, this Chapter also discusses their properties and the methods of immobilization at device surfaces. The principles of electrochemical, optical and mass sensitive biosensor technology will be explained together with examples of application of these techniques for detection bacterial pathogens by aptamer-based biosensors.