ABSTRACT
Electrochemical sensing of DNA hybridization using low-density DNA microarrays attracts tremendous interest in various elds including disease diagnosis and environmental and warfare agent detection. The electrochemical method is simple, sensitive, cost-effective, compatibility with mass fabrication of sensor elements, and miniaturized portable sensor devices for onsite evaluation of samples compared to the conventional •uorescence and radioactivity-based assays. A typical electrochemical DNA sensor consists of a solid electrode (Figure 39.1A), an electrochemical analyzer (Figure 39.1B), and surface-conned DNA probes (called hereafter as recognition layer) (Figure 39.1A). The hybridization between the preimmobilized HS-single-stranded DNA (ssDNA) (Figure 39.1C) and target DNA probes is transduced into an electrical signal (Figure 39.1D). Numerous papers have been published on various electrochemical DNA sensors and reviewed recently [1-18]. In-depth discussion is out of scope of this chapter and limited to cancer diagnosis by DNA hybridization using gold transducer and electrochemical technique. Cancer caused by mutations in somatic cells and other genetic diseases are caused solely by mutations in germ line [19]. Predisposition of inherited genetic mutations results in a specic type of cancer. Depending
39.1 Introduction ...................................................................................................................................671 39.1.1 Electrochemical DNA Biosensors ....................................................................................671
