Oligonucleotide hybridization biosensors

An electrochemical DNA hybridization biosensor basically consists of an electrode modified with a single stranded DNA called probe [109]. Usually the probes are short oligonucleotides (or analogues such as peptide nucleic acids). The first and most critical step in the preparation of an electrochemical DNA biosensor is the immobilization of the probe sequence on the electrode. The second step is the hybrid formation under selected conditions of pH, ionic strength and temperature. The next step involves the detection of the double helix... 

Molecular beacons (MBs) are hairpin-shaped oligonucleotides that report the presence of specific nucleic acids. The MBs have been immobihzed by Tan and co-workers [27] onto ultrasmall optical fibre probes through avidin-biotin binding. The MB-DNA biosensor detected its target DNA molecules, in real time, with selectivity for a single base-pair mismatch. This MB-DNA-biosensor was used by Perlette and Tan [28] for real-time monitoring of mRNA-DNA hybridization inside a living cell. 

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