A Novel Type of Nucleic Acid-based Biosensors: the Use of PNA Probes, Associated with Surface Science and Electrochemical Detection Techniques

DNA biosensors are now recognized as unvaluable tools for detecting target genes responsible for diseases, or pollution, in various fields (Fodor et al., 1991; DeRisi et al., 1997; Landegren et al., 1998). Therefore, detection of DNA hybridisation is of significant scientific and technological importance, as manifest, for example, from the growing interest in chip-based characterisation of gene expression pattern and detection of pathogens. DNA biosensors technologies are currently under intense investigation owing to their great promise for rapid and low-cost detection of specific DNA sequences. These technologies commonly rely on the immobilisation of a single-strand (ss) DNA probe onto optical, electrochemical, or mass-sensitive transducers (Xu et al., 1995; Mikkelsen et al., 1996; Okahata et al., 1992). There is still a crucial need to improve the sensitivity, selectivity and rapidity of the DNA hybridisation detection. Among the possible strategies, a new artificial Peptide Nucleic Acid (PNA), a highly specific probe, combined with the use of surface science techniques to optimise the sensing layer as well as to detect biomolecular recognition, open promising ways to win this biotechnological challenge. This chapter will focus on these two novel aspects of DNA biosensors.