DNA, detection

Electrical conductivity measurements revealed that ionic conductivity of Ag-starch nanocomposites increased as a function of temperature (Fig.l7) which is an indication of a thermally activated conduction mechanism [40]. This behavior is attributed to increase of charge carrier (Ag+ ions) energy with rise in temperature. It is also foimd to increase with increasing concentration of Ag ion precursor (inset of Fig.l7). This potentiality can lead to development of novel biosensors for biotechnological applications such as DNA detection. 

Wang J (2003) Nanoparticle-based electrochemical DNA detection. Anal Chim Acta 500 247-257... 

Urdea, M. S. (1992). Theoretical aspects of nucleic acid standardization for HBV DNA detection. Report on the Sixth Eurohep Workshop, 3.1.2c. 

Hagiwara Y, Hasegawa T, Shoji A et al (2008) Acridone-tagged DNA as a new probe for DNA detection by fluorescence resonance energy transfer and for mismatch DNA recognition. Bioorg Med Chem 16 7013-7020... 

Fang C, Agarwal A, Devi Buddharaju K et al (2008) DNA detection using nanostructured SERS substrates with Rhodamine B as Raman label. Biosens Bioelectron 24 216-221... 

Direct electrostatic DNA detection by its intrinsic molecular charge... 

Most of the experiments for detecting charged macromolecules with FEDs, reported in literature, have been realized using a transistor structure [11-36], Recent successful experiments on the detection of charged biomolecules as well as polyelectrolytes with other types of FEDs, namely semiconductor thin him resistors [39 11], capacitive MIS [42] and EIS structures [43-50], have demonstrated the potential of these structures - more simple in layout, easy, and cost effective in fabrication - for studying the molecular interactions at the solid-liquid interface. A summary of results for the DNA detection with different types of FEDs is given in Table 7.1. 

DIRECT ELECTROSTATIC DNA DETECTION BY ITS INTRINSIC MOLECULAR CHARGE... 

In contrast to the DNA detection by its intrinsic molecular charge, even in high ionic-strength solutions (0.5 M), where the hybridization efficiency is high and the hybridization event can be faster, a detectable sensor signal can be achieved. The estimations performed under the assumptions presented in Fig. 7.8 predict signal values of about 28-35 mV. 

F. Pouthas, C. Gentil, D. Cote, and U. Bockelmann, DNA detection on transistor arrays following mutation-specific enzymatic amplification. Appl. Phys. Lett. 84, 1594-1596 (2004). 

Owing to their unique (tunable-electronic) properties, semiconductor (quantum dots) nanocrystals have generated considerable interest for optical DNA detection [12], Recent activity has demonstrated the utility of quantum dot nanoparticles for enhanced electrical DNA detection [33, 34, 50], Willner et al. reported on a photoelectrochemical transduction of DNA sensing events in connection with DNA cross-linked CdS nanoparticle arrays [50], The electrostatic binding of the Ru(NH3)63+ electron acceptor to the dsDNA... 

X. Zhao, R. Tapec-Dytioco, and W. Tan, Ultrasensitive DNA detection using highly fluorescent bioconjugated nanoparticles. J. Am. Chem. Soc. 125, 11474-11475 (2003). 

Current methods for DNA detection usually require enzymatic amplification of the target DNA sequence prior to analysis. For example, the PCR technique selectively increases the concentration of the target sequence relative to unrelated sequences. PCR methods, however, introduce ambiguities resulting from contamination by different DNA sequence. Therefore, a definitive method is required for the analysis of a single, original DNA sequence. To achieve this objective, the sensitivity and speed of the chemiluminescent enhancement techniques described in this chapter must be improved. 

Summarizing, some of the organic dyes, particularly cyanines, are able to form fluorescent aggregates on DNA. Comparing with the dye monomers bound to DNA, the J-aggregates are more sensitive to the concentrations ratio and to DNA nucleotides content. Though these structures can hardly be applied for the routine DNA detection assays, they are rather interesting systems for special studies. 

Liu B, Bazan GC (2009) Homogeneous fluorescence-based DNA detection with water-soluble conjugated polymers. Chem Mater 16 4467 1476... 

Fig. 9 Illustration of interaction between polymer and DNA single stranded bait to form the duplex to which the DNA binds to form a double helix triplex resulting in colorimetric and fluorometric DNA detection [19]...

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