The Electrochemistry Of Self-assembled DNA

The Electrochemistry of Self assembled DNAWith the rapid progress in Human Genome Project, great efforts have been madeto develop the heterogeneous genosensors for the DNA dctection, and genechipscomprise a new and uprising brightphear1 of biological tec:hnology emerging at atremendous pace in the 21st century. However, since th(! genosensors study isunderway, many fundamental issues were generally not well understood and theremain prob1ems to be resolved wi1l be mandatory. T'he development of agenosensor involves the following key technique processes:i ) In view of the fact that the area of surface modification and the efficientprobe immobilization comprises a crucial e1ement in genosensor design, in additionto investigahon of new strategies for linking nucleic acid to surfaces and choice ofnew substrate materials, by extension it is clear that signftficant further study byadjunct surface analysis wll be mandatory involving orientation, packing density,mu1tipoint adsorption considerations. Such an effOrt has bc:en noticeab1y 1acking insome of the earlier work on the development of genosensors.ii ) How to gain higher hybridization efficie11cies, how about thethermodynamics and kinetics of DNA hybridization on sensor interfaces, how theinterface electrostatics effect the thermodynamics and kinetics of interfacialhybridization of immobilized DNA probes wth target sequences in so1ution are the'T'he ElectrOChemisny of SeIf-aSsembled DNA.remsin problems to be resolved. Furthermore, the thermodynamics and kinetics ofDNA hybridization on sensor interface requires modeling in order to explain a seriesof prob1ems about the variation of the thermodynamic and the kinetic parameters.iii) Transduction and detection of interfacial DNA hybridization are needed tobe investigated thoroughly. Employing the electrochemical DNA biosensors on genedetection is confined due to electroactive hybridization indicator. More sophisticatedelectroactive labels with high selectivity and sensitivity and the labels which canrecognize specific DNA structure, such as mismatch, remain to be developed.Additional1y, further investigation of the label-free eIectrochemica1 detectionschemes based upon the variation of interfaciaI impedance, capacitance, or thephotoelectric behavior resulting from hybridization is much needed.As we have seen, a number of fundamental issues remain to be addressed, whichis dependent upon the continued development through combined efforts in manysubjects. On the one hand, the electrochendcal method is a simple, fast, sensitive,non-radioactive and in situ method. On the other hand, e1ectrochemical methods canalso be useful tools to qua1itative1y or quantitatively describe the interaction betweentwo mo1ecu1es occurring on the electrode interface according to the differences intheir interfacial behaviors. The exPeriences obtained from employing the traditionale1ectrochemical methods, the electrochendcal in situ spectroscopy and microscopyon investigating the behaviors at the electrode/solution interface may provide ussome new ideas about biosensing research. The progress provides some effectivemeans for the further development of biosensing technique. However, the in situprobing structural change employing the electrochemical in situ spectroscopies hasnot been made in those studies.Accordingly, the emphasis of this thesis is placed on solving and investigatingsome above key processes involved in biosensing technique employing thee1ectrochendcal ex situ and in situ SERS (surface enhanced Raman scattering)spectroscopy, QCM (quartz crystal microbalance) and the tradihonal electrochemicalmethods such as Impedance Spectroscopy. In short, the following issues have beenconducted. Firsdy, the oligonucleotide probes were immobilized on the goldsubstrate by self assembly of thio1-derivatized oligonucleotide probes (ssDNA).Second1y, the potential dependency of the e1ectrochemic...