Nucleic Acid Hybridization Biosensors

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. 

In the last decade there has been a considerable interest in DNA biosensors due to its significant anal)Aical properties. The most popular application of DNA biosensors is based on nucleic acid hybridization detection of specific DNA sequences [19]. 

Such biosensors have many potential applications — for example, identification of genes that are implicated in inherited diseases, single nucleotide polymorphisms (SNP), and some mutations that play a major role in causing diseases [20-21], identification of pathogenic microorganisms which are responsible for infectious diseases [22-23], transgenic organisms for food quality [24], detection 

Nucleic acid biosensors can be classified on the basis of their transduction technology. The transducer converts the nucleic acid hybridization recognition into a measurable anal3ttical signal [27-28]. Electrochemical, optical, piezoelectrical, acoustical, and mechanical transducers are among the many types found in DNA biosensors. 

Piezoelectric biosensors are mass-sensitive biosensors which can produce a signal based on the mass of chemicals that interact with the sensing film. Quartz Crystal Microbalance (QCM) sensorsa 

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Label-based electrochemical nucleic acid hybridization biosensors work on the principle of the following groups ... 

Nucleic acid biosensors based on optical modes of detection represent another common approach for generating analytical signals based on nucleic acid hybridization. The methods discussed herein are based on methods that are suitable for the study of materials on surfaces. There are a number of different optical methods that have been described, with the most common being attenuated total reflectance (ATR), total internal reflection fluorescence (TIRF) and surface plasmon resonance (SPR) [15]. All of these methods work... 

Optical nucleic acid biosensors and microarrays based on fluorescence detection make use of fluorescent dyes to provide a measurable signal for target/probe hybridization. Ideally, fluorophores used for detecting nucleic acid hybridization should exhibit large molar absorptivity, resistance to pho-tobleaching, quantum yields that approach unity and the abibty to produce a resolvable signal at low concentrations both quickly and reproducibly [40]. 

Keywords Biosensor QCM Nucleic Acids Hybridization Aptamers... 

Nucleic Acid-Based Biosensors. Nucleic acid biosensors have been created most commonly based upon detecting the extent of hybridization of an... 

Nucleic acid is a biosensor which integrates nucleic acid hybridization recognition with a signal transducer. Figure 13.1 is a schematic representation of a nucleic acid biosensor. 

DNA biosensor [332] Nucleic acid hybridization annealing between the ssDNAs from different sources DNA biosensors can detect the presence of genes or mutant genes associated with inherited human diseases... 

Karadeniz A, Kuralay F, Abaci S, Erdan A (2011) The recent electrochemical biosensor technologies for monitoring of nucleic acid hybridization. Curr Anal Chem 7 63-70... 

Results on DNA-based biosensors will be presented they have been used mainly for two kind of applications 1) for the determination of low-molecular weight compounds witlr affinity for nucleic acids and 2) for the detection of hybridization reaction. 

Electrochemical DNA biosensors are based on the use of nucleic acids or analogues as biorecognition element and electrochemical techniques for the transduction of the physical chemical signal. Two aspects are essential in the development of hybridization biosensors, sensitivity and selectivity. Traditional methods for detecting the hybridization event are too slow and require special preparation. Therefore, there is an enormous interest in developing new hybridization biosensors, and the electrochemical represent a very good alternative [108]. 

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... 

Many DNA-based biosensors (genosensors) are based on the ability of complementary nucleic acid strands to selectively form hybrid complexes. The complementary strands anneal to one another in a Watson-Crick manner of base pairing. Hybridization methods used today, such as microhtre plates or gel-based methods, are usually quite slow, requiring hours to days to produce reliable results, as described by Keller and Manak [10]. Biosensors offer a promising alternative for much faster hybridization assays. 

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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