DNA Hybridization Biosensors

FIGURE 6-14 DNA hybridization biosensors detection of DNA sequences from the E. coli pathogen. Chronopotentiometric response of the redox indicator upon increasing the target concentration in i. 0 pg/mi steps (a-c), in connection with a 2 min hybridization time. (Reproduced with permission from reference 46.) 

Experimental arrangement for electrochemical DNA h3djridiza-tion biosensors includes the following  

Label-free and indicator (reagent)-less detection of target DNA typically based on guanine residues response. 

Noncovalent redox indicators that allow distinguishing between the ssCP and dsDNA hybrid at the electrode surface (successful hybridization) [22,23]. 

Sandwich hybridization assay that employs a covalently labeled reporter or signaling probe (RP) and involves two tDNA recognition steps (CP-tDNA and tDNA-RP) [32]. The RPs are designed to hybridize with the tDNA at a site next to the sequence recognized by the capture probe to confer efficient electronic communication between the label and the electrode. 

Peptide nucleic acid (PNA) probes as a DNA analogue that possess an uncharged pseudopeptide backbone instead of the charged phosphate-sugar backbone of natural DNA and, consequently, greater affinity to complementary DNA and better distinction between closely related sequences [33]. 

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Figure 6.16 Steps involved in the detection of a specific DNA sequence using an electrochemical DNA hybridization biosensor. (Reproduced with permission from Ref. 71.)...

Electrochemical devices have proven very useful for sequence-specific biosensing of DNA. Electrochemical detection of DNA hybridization usually involves monitoring a current response under controlled potential conditions. The hybridization event is commonly detected via the increased current signal of a redox indicator (that recognizes the DNA duplex) or from other hybridization-induced changes in electrochemical parameters (e.g., conductivity or capacitance). Modern electrical DNA hybridization biosensors and bioassays offer remarkable sensitivity, compatibility with modern microfabrication technologies, inherent miniaturization, low cost (disposability), minimal power requirements, and independence of sample turbidity or optical pathway. Such devices are thus extremely attractive for obtaining the sequence-specific information in a simpler, faster, and cheaper manner, compared to traditional hybridization assays. 

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... 

J, J, Gooding, Electrochemical DNA hybridization biosensors. Electroanalysis 14[17], 1149-1156 C2002). 

M. Diaz-Gonzalez, A. de la Escosura-Muniz, M. B. Gonzalez-Garcia, and A. Costa-Garcia, DNA hybridization biosensors using polylysine modified SPCEs, Biosens. Bioelectron. 23(9), 1340-1346 (2008). 

The nucleic acid recognition part selectively detects a specific gene sequence of DNA. A DNA hybridization biosensor uses a DNA strand of known sequence as a probe of a target DNA sample. 

L. S. Elicia Wong, F. J. Mearns, and J.). Gooding, Further development of an electrochemical DNA hybridization biosensor based on long-range electron transfer. Sens. Actuators. B Chem. 111-112,515-521 (2005). 

Electroactive labels introduced into DNA also possess electrochemical signals at less extreme potentials than intrinsic DNA responses. An example is electroactive osmium tetraoxide with 2,2 -bipyridine bound to free 3 -ends of the ss regions created by a DNA repair enzyme exonuclease III, which responds to the extent of DNA damage [25]. The technique is capable of detection of one lesion per 10 nucleotides in supercoiled plasmid DNA. DNA-hybridization biosensors were proposed for studies of DNA damage by common toxicants and pollutants where voltammetric transduction was achieved by coupling ferrocene moiety to streptavidin linked to biotinylated target DNA [26]. 

Nowicka AM, Kowalczyk A, Stojek Z, Hepel M (2010) Nanogravimetric and voltammetric DNA-hybridization biosensors for studies of DNA damage by common toxicants and pollutants. Biophys Chem 146 42-53... 

In the following sections we will focus on the major steps involved in electrochemical DNA hybridization biosensors, namely the formation of the DNA recognition layer, the actual hybridization event, and the transformation of the hybridization event into an electrical signal (Figure 2). As will be illustrated below, the success of such devices requires a right combination of synthetic-organic and surface chemistries, DNA recognition, and electrochemical detection schemes. 

Electrical DNA hybridization biosensors are capable of converting DNA-DNA recognition events into an electronic signal-transduction process and identify different species in food. Further work is needed to realize the full potential of this new class of biosensors for the analysis of large DNA sequences and its application in species identification. 

Tichoniuk, M., Gwiazdowska, D Ligaj, M. and Filipiak, M. (2010) Electrochemical detection of foodbome pathogen aeromonas hydrophilaby DNA hybridization biosensor. Biosens. Bioelectron., 26 (4), 1618-1623. 

L. Malic, T. Veres, M. Tabrizian, Biochip functionalization using electrowetting-on-di-electric digital microfluidics for surface plasmon resonance imaging detection of DNA hybridization. Biosensors and Bioelectronics 24 (2009) 2218-2224. 

Steps involved in electrochemical DNA hybridization biosensors include ... 

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