Electrochemical Detection Of Nucleotide Substances On New Chemically Modified Carbon Paste Electrode

With the distribution of nucleic acids, nucleotides was found in various organsand tissues of organism and involved in biological, genetic and other basic activities asa component of nucleic acids. It has important significance to study nucleotidemolecules. In this thesis different chemically modified electrodes were fabricated andused to investigate the electrochemical behaviors of nucleotide molecules. The thesiscan be summarized as follows:1. Two kinds of modified electrodes were constructed by mixing graphite powderand paraffin oil with hydrophobic ionic liquids （IL）1-octyl-3-methylhexafluorophosphate （[OMIM]PF₆） or diphenylacetylene （DPA）. The electrochemicalbehaviors of guanoside-5’-monophosphate （GMP） and adenosine triphosphate （ATP）were studied on the CILE and CMWE, respectively. Due to the presence of highconductive IL and DPA on the electrode, modified electrode exhibited excellentelectrocatalytic ability to GMP and ATP. The electrode reaction parameters such as theelectron transfer coefficient （α）, the electron transfer number （n）, the apparentheterogeneous electron transfer rate constant （ks） and the surface coverage （ГT） werecalculated, respectively. The detection limit of were calculated as1.6×10^-7mol/L （3σ）for GMP and1.28×10^-8mol/L （3σ） for ATP by differential pulse voltammetry.2. Graphene （GR） and chitosan （CTS） composite film modified carbon molecularwire electrode （CTS-GR/CMWE） was fabricated and used to investigate theelectrochemical behavior of ATP. By using differential pulse voltammetry （DPV） asthe detection technique, the oxidation peak current showed good relationship with the ATP concentration in the range from1.0nmol/L to700.0μmol/L with the detectionlimit as0.342nmol/L （3σ）. The common coexisting substances, such as uric acid,ascorbic acid and GTP, showed no interferences to the ATP detection.3. Two kinds of modified electrodes （CTS-GR-IL/CMWE） were fabricated byusing graphene （GR）, chitosan （CTS）, hydrophobic ionic liquid [OMIM]PF₆orhydrophilic1-ethyl-3-methylimidazolium tetrafluoroborate （[EMIM]BF4） compositematerials modified carbon molecular wire electrode. And the modified electrode wascharacterized by electrochemical impedance spectroscopy and cyclic voltammetry. Theelectrochemical behaviors of adenosine monophosphate （AMP） andguanosine-5’-triphosphate （GTP） were studied on the CTS-GR-IL/CMWE with theelectrochemical parameters calculated respectively. A good linear relationship wasestablished between the differential pulse voltammetric current and AMPconcentration in the range from1.0×10^-8mol/L to4.0×10-4mol/L with the detectionlimit of3.42×10^-9mol/L （3σ）. The differential pulse voltammetric current showed agood linear relationship with the GTP concentration in the range from7.0×10^-9mol/Lto3.0×10-4mol/L with the detection limit of2.32×10^-10mol/L （3σ）.