| With the deeper research on the structure and function of human gene, especially the fast progress of the Human Genome Project, the study on DNA diagnosis and gene treatment of human disease has been greatly promoted. Many genes inducing disease were discovered and identified. Little changes in DNA sequence, such as base-pair displacement, lack and manifold, numerous inherited human disorders could appear. So much effort is needed to detect the specific DNA sequences related to diseases, which is also helpful for the selection of genes and the development of drugs, clinical diagnosis, epidemic prevention, environmental protection and bioengineering.Traditional DNA probes are labeled with radioisotopes. Although this method gives high sensitivity, the radioactive labels present many problems such as a potential hazard to analyst and environment, and time-consuming. In order to overcome these problems, a series of non-radioactive DNA probes such as fluorescent, chemiluminescent and electrochemical probes have been developed. Among these, electrochemical DNA biosensor is a novel technique that combining biochemical, electrochemical, medical and electronic techniques with the advantages of being simple, reliable, cheap, sensitive and selective for genetic detection. So it is of great significance in biology molecular and bioengineering.The emergence of nanotechnology is opening new horizons for the application of nanoparticles in analytical chemistry. In particular, nanoparticles are of considerable interest in the world of nanoscience owing to their unique physical and chemical properties. Such properties offer excellent prospects for chemical and biologicalsensing. The power and scope of such nanoparticles can be greatly enhanced by coupling them with biological recognition reactions and electrical processes (i.e. nanobioelectronics). Nanoparticle-biopolymer conjugates offer great potential for DNA diagnostics.This paper aims at studying nanoparticles-based novel electrochemical DNA biosensors, using semiconductor quantum dot tags, nanoparticles modification electrode and magnetic (separation) beads. Remarkable sensitivity is achieved by coupling particle-based amplification units and various amplification processes. The use of nanoparticle tracers for designing multi-target electrochemical coding protocols also is presented.Chapter 1 PrefaceFirstly, we introduce the progress of DNA biosensor, including its principle (probe identification principle and immobilization method of ssDNA on solid support) and its classification (electrochemical DNA biosensor, optical DNA biosensor and piezoelectric DNA biosensor). Among these, we emphatically review the principle, progress, the application and development trends of electrochemical DNA biosensors. Second, the application of nanoparticles on analytical chemistry was introduced. At last pointed out the purpose and significance of the dissertation.Chapter 2 Co(bpy)33+-doped silica nanoparticle DNA probe-based electrochemical DNA biosensorA new and sensitive electrochemical DNA hybridization detection assay, using (Co(bpy)33+)-doped silica nanoparticles as the oligonucleotide (ODN) labeling tag, and based on voltammetric detection of Co(bpy)33+ inside silica nanoparticles, is described. Electro-active Co(bpy)33+ is not possible for directly linking with DNA, it is doped into the silica nanoparticles in the process of nanoparticles synthesis for DNA labeling. The Co(bpy)33+ labeled DNA probe is used to hybridize with targetDNA immobilized on the surface of glassy carbon electrode. Only the complementary sequence DNA (cDNA) could form a double-stranded DNA (dsDNA) with the DNA probe labeled with Co(bpy)33+ and give an obvious electrochemical response. A three-base mismatch sequence and non-complementary sequence had negligible response. Due to the large number of Co(bpy)33+ molecules inside silica nanoparticles linked to oligonucleotide DNA probe, the assay showed a high sensitivity. It allows the detection at levels as low as 2.0 X 10-10mol l-1of the... |
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