The Surface Hybridization Of DNA With Morpholino: Fundamental And Applications

Nucleic acids are one of the most fundamental bio-molecules in life which play an important role in the replication and synthesis of proteins. With the development and merging of molecular biology with nano science, nucleic acid has exhibited its potential to be an important molecular tool. A series of biosensors and molecular devices have been made by nucleic acids in biology and medical diagnosis. However, the application of these devices made by the natural nucleic acids is limited considering its properties such as the dependence of the thermodynamics of DNA-DNA duplex upon ionic strength and its low anti-enzymolysisability. Combination of natural nucleic acids with the synthetic analogs of nucleic acids like morpholino(MO) is promising to improve the thermo stability and anti-enzymolysisability of the formed duplex and broaden the application of DNA in the fabrication of molecular devices. Therefore, study of the fundamentals of MO-DNA hybridization is of great importance.This work mainly studied the factors that influence the surface hybridization of DNA-MO, specifically, the length of the complementary DNA and the hybridization position. Besides, the enzymolysis features of MO and DNA immobilized on gold nanoparticles are also studied. The results provide theoretical basis for constructing molecular devices. Furthermore, we tried to detect the mercuric ion (Hg2+) using a functionalized single plasmonic gold nanoparticle.1. An electrochemical study of the surface hybridization process of morpholino-DNA:thermodynamics and kineticsMO was immobilized on the gold electrode. It hybridized with target DNAs which were labeled with an electrochemical active group. Cyclic voltammetry was used to study the hybridization procedure. The results show that MO has strong binding ability with DNA on the electrode. The longer MO-DNA complementary base pair leads to faster hybridization, higher hybridization efficiency and more stable MO-DNA duplex. Moreover, MO-DNA hybridization reveals different properties when they hybridize at different position of MO. Analysis show that there exists electrostatic repulsion force between MO-DNA duplexes on the surface microenvironment thus affects the thermodynamic and kinetic properties. Keyword:Morpholino, DNA, surface hybridization, cyclic voltammetry2. The study of the enzymolysis features of MO and DNA immobilized on gold nanoparticleIn this chapter, we modified gold nanoparticle with fluorophore labeled DNA and studied the enzymolysis features of MO-DNA/DNA-DNA on gold nanoparticle by detecting the solution’s fluorescence signal. The results show that MO can enhance the enzymolysis resistance ability of its complementary DNA upon formation of double strand but cannot protect the extended single DNA strand of MO-DNA duplex. Besides, MO-DNA duplex still has the hybridize and dehybridize activity after they interact with the enzyme. Keyword:Morpholino, DNA, gold nanopariticle, enzymolysis, fluorescence detection.3. The preliminary study of detecting mercuric ion(Hg2+) based on the surface plasmon resonance(SPR) of a single gold nanoparticle(GNP)Mercuric ion is a toxic mental ion and can accumulate in living organisms. It has a high cellular toxicity. Therefore, the development of a high efficient and sensitive detection method is an important topic. A DNA functionalized gold nanoparticle was made to bind with Hg2+ by forming T-Hg2+-T complex. The scattering spectrum of a single gold nanoparticle will altered when Hg2+ was bind to the GNP. Experimental results show that this research may hide different reaction mechanism under the observed spectrum shift. Based on the above analysis we proposed advices for the further improvement of this method.