Nucleic Acid Based Electrochemical Biosensors for Multiplexed Investigation of Bioagents

The need for rapid, reliable, specific, and sensitive methods of detecting pathogens, at low cost, is the focus of a great deal of research. To meet expectations of users, analytical methods for pathogen detection must have the specificity to distinguish between different bacteria, the adaptability to detect different analytes, and the sensitivity to detect bacteria on-line and directly in real samples without preenrichment. The device must also be simple and inexpensive to design and manufacture. Multiplexing, or simultaneous detection of multiple analytes, is another important prerequisites for pathogen detection. (Bio)sensor technology is claimed to satisfy these requirements. In recent years various kinds of electrochemical biosensors based on identification of the bacterial nucleic acid have been developed. The development of DNA-based biosensors for the detection of specific nucleic acid sequences consists in the immobilization, onto the surface of a chosen transducer, of an oligonucleotide with a specific base sequence called capture probe. The complementary sequence (target) present in the sample solution is recognized and captured by the probe through the hybridization reaction. The evaluation of the extent of the hybridization allows one to conclude whether the sample solution contains the complementary sequence of the probe or not. Electrochemical transducers have received considerable attention in connection with the detection of DNA hybridization. This paper will give an overview of two different multiplexed ­electrochemical approaches of pathogen detection using nucleic acid developed in author’s lab, and based on screen-printed electrode array and on scanning electrochemical microscope respectively.