The Application Of Electrochemical Quartz Crystal Microbalance (EQCM) On The Study Of DNA

Electrochemical quartz crystal microbalance(EQCM) is one of the effective method in the molecular biology and the microchemistry field because it is simple, quick and the 10-9g detection limit. So a method of fast, cheap and simple is supplied for DNA analysis and disease diagnosis by the difference recognition and orient cleavage via the using of EQCM. At present, many these published demonstrate that there are many secretes still in dark to be exposed by us, and the orient cleavage of DNA by EQCM has never been reported. In this thesis, we systematically studied the difference recognition, the orient cleavage of DNA and the sensitivity improvement of EQCM in the DNA detection. We first study the mobilization of 20mer-ODN and it's twice hybridization with 10mer-ODN and 8mer-ODN on gold electrode of EQCM. Then, we study the orient cleavage of DNA on the EQCM electrode by Ce(IV)ions for the first time because of the wide application of the DNA orient cleavage for the DNA recomposing. And speculating the mechanism. The experiment results show that the ss-DNA not only can be modified on the gold electrode firmly by Au-S bonds, but also can hybridize with the complementary strands effectively. And Ce(IV) ions can hydrolytic cleave DNA at the random or specific site. On the basis of those researches, we improve the sensitivity of EQCM in the DNA detection via the modification of gold nano-particles on the gold electrode. Then we study the influence of the mismatch number and the site on the hybridization. The results indicate that the sensitivity of EQCM is improved obviously due to the using of the gold nanoparticles. Moreover, the difference of the mismatch number and the site have great influence on the hybridization. The same result is proved by the experiment of the fluorescence spectrum We design a kind of DNA like molecular beacon which is called MB-type DNA (The fluorephore and quencher are displaced by alkyl strand modified with thiol) in order to improve the sensitivity of EQCM for the DNA detection. And then, the...