Deoxyribonucleic acid sensors

In particular, the unique properties of polypyrrole-carbon nanotubes allowed the detection of hybridization reactions with complementary deoxyribonucleic acid sequences via a decrease in impedance [115], Alternatively, similar deoxyribonucleic acid sensors have been created from a composite of polypyrrole and carbon nanotube functionalized with carbon groups to covalently immobilize deoxyribonucleic acid into carbon nanotubes [116, 117]. Carbon nanotubes have also been incorporated into biosensors as nanotube arrays into which enzymes can be immobilized, along with a conducting polymer [118] and a polypyrrole dopan [119]. In general, the presence of carbon nanotubes tends to increase the overall sensitivity and selectivity of biosensors. 

D.S. Kim, H.J. Park, H.M. Jung, J.K. Shin, Y.T. Jeong, P. Choi, J.H. Lee, and G. Lim, Field-effect transistor-based biomolecular sensor employing a Pt reference electrode for the detection of deoxyribonucleic acid sequence. Jpn, J. Appl. Phys. 43, 3855-3859 (2004). 

X. Sun, P. He, S. Liu, L. Ye and Y. Fang, Immobilization of single-stranded deoxyribonucleic acid on gold electrode with self-assembled aminoethanethiol monolayer for DNA electrochemical sensor applications, Talanta, 47 (1998) 487-495. 

Relatively recently Fe/S proteins have been found to function in the regulation of biosynthesis. This can be by promoting deoxyribonucleic acid (DNA) transcription, e.g. the [2Fe-2S] containing Escherichia coli superoxide-activated (SoxR) transcription activator [10-12], or the presumably [4Fe-4S]-containing E. coli transcription factor fumarate nitrate reduction (FNR) [13,14], Alternatively, the Fe/S protein can act by interference with messenger ribonucleic acid (mRNA) translation, i.e., the iron regulatory proteins (IRPs) [15,16], These interactions are stoichiometric, therefore not catalytic. Presumably, they are also a form of sensoring, namely, of oxidants and/or iron [17],... 

Figure 2.31 Schematic diagram of the immobilization and hybridization of DMA on Au/ nanoPAN/GCE. (Reprinted with permission from Analytica Chimica Acta, Enhanced Sensitivity for deoxyribonucleic acid electrochemical impedance sensor Gold nanoparticle/polyaniline nanotube membranes by Y. Eeng, T. Yang, W. Zhang, C. Jiang and K. Jiao, 616, 2, 144-151. Copyright (2008) Elsevier Ltd) (See colour Plate 1)...

Feng, Y, Yang,T, et al. Erihanced sensitivity for deoxyribonucleic acid electrochemical impedance sensor Gold nanoparticle/polyaniline nanotube membranes. Analytica chi-mica acta,616(2), 144-151 (2008). 

The benefits of modifying EIS structures with LbL films to achieve biosensors with improved performance was also reported by Abouzar et al., who observed an amplification of the signal response upon alternating layers of polyelectrolytes and enzymes as gate membranes on the p-Si-Si02 EIS structure [99]. A new variant of EIS sensors has been produced, which comprised an array of individually addressable nanoplate field-effect capacitive biochemical sensors with an SOI (silicon-on-insulator) stmcture to determine pH and detect penicillin. It also allows for the label-free electrical monitoring of formation of polyelectrolyte multilayers and DNA (deoxyribonucleic acid)-hybridization event [100]. 

Recent advances in carbon nanotnbe technology inclnde the incorporation of carbon nanotubes into a number of conducting polymer-based biosensors. For example, preliminary studies have been performed exploring the properties of both polypyrrole-carbon nanotube and polyaniline-carbon nanotnbe devices as pH sensors [114], One application used deoxyribonucleic acid-doped polypyrrole in conjunction with carbon nanotubes for detection of deoxyribonucleic acid. 

Wang B, Du X, Zheng J, Jin B (2005) Electrochemical sensor based on immobilization of single stranded deoxyribonucleic acid on Pt electrode surface by avidin-biotin system. Fenxi Huaxue 33(6) 789-792... 

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