Sequence-specific biosensor

Sequence-specific biosensor, 183, 185 Selectivity, 92, 143, 147, 155 Selectivity coefficient, 143 Self-assembled monolayers, 39, 118 Selenium, 85 Sensor, 171 Silver halide, 159 Simulation, 35... 

Biomolecules-functionalized CNTs can result in characteristic electric conductivity changes of CNTs (Hou et al., 2003), which may be developed into specific biosensor for ultrasensitive detection of biomolecules such as DNA molecules, bacteria and vims, etc. We also observed that oligo DNA-filled SWCNTs appeared as characteristic Electric Resistance peaks as shown in Fig. 9.22, which also may be used as biosensor to detect biomolecules or sequence DNA sequences. 

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. 

Ou,L. J., JinJ. Y.,etal. Sensitiveand Visual Detection of Sequence-Specific DNA-Bind-ing Protein via a Gold Nanoparticle-Based Colorimetric Biosensor. "Analytical Chemis-hy,82(14), 6015-6024 (2010). 

Zhang, C., Xu, J., Zhang, S. et al. (2012) One-pot synthesized DNA-CdTe quantum dots applied in a biosensor for the detection of sequence-specific oligonucleotides. Chemistry (Weinheim an der Bergstrasse, Germany), 18 (27), 8296-8300. 

Wang, J., Palecek, E., Nielsen, P.E. et al. (1996) Peptide nucleic acid probes for sequence-specific DNA biosensors. Biochemistry, 7863 (10), 7667-7670. 

Rai, V., Nyine, Y.T., Hapuarachchi, H.C. et al. (2012) Electrochemically amplified molecular beacon biosensor for ultrasensitive DNA sequence-specific detection of Legionella sp. Biosens. Bioelectron., 32 (1), 133-140. 

A label-free electrochemical DNA biosensor based on 4,4 -diaminoazobenzene (4,4 -DAAB) and multiwalled carbon nanotube (MWNT)-modified GCE for short DNA sequences related to HBV hybridization detection was presented by Li et al. [92]. DPV was used to investigate hybridization event. The decrease in the peak ciurent of 4,4 -DAAB was observed on hybridization of probe with the target. This electrochemical approach was sequence specific as indicated by the control experiments, in which no peak eurrent change was observed when a non complementary DNA sequence was used. Numerous factors affecting the target hybridization were optimized to maximize the sensitivity. Under optimal conditions, this sensor showed a good calibration range between 7.94 xlO M and 1.58 xlO M, with HBV DNA sequence deteetion limit of 1.1 xlO M. 

DNA biosensors such as conventional DNA microarrays make use of sequence-specific DNA detection. They consist of an immobilized DNA strand to detect the complimentary sequences by DNA-DNA hybridization. The newly developed lab on a chip concept is essentially an adaptation of DNA chips to content channels and chambers for flowing liquids, thus avoiding its limitations. They integrate, on a single chip, modules for DNA extraction, purification, amplification, and detection, most of them using microfluidic capillary electrophoresis devices. 

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