| Carbon nanotubes?CNTs?,an up-rising star of carbon-based material,have a considerable attention in electrochemical sensors due to its unique nanostructure and superb properties,such as large specific surface area,strong adsorptive ability,desirable electrical conductivity and good biocompatibility.Nevertheless,CNTs are mostly susceptible to agglomeration via strong?-?stacking or van der Waals forces,which severely restricts its further application.In order to overcoming this obstacle,CNTs are required to be covalently or non-covalently functionalized.In this paper,the primitive MWCNTs were first functionalized by mixture acid or aromatic compounds to improve their dispersibility and conductivity.Then the obtained MWCNTs were used to modify the surface of glassy carbon electrode,which were applied to the electrochemical detection of 8-Hydroxy-2?-deoxyguanosine?8-OHdG?,DNA damage and purine bases.The main contents were summarized as follows:1.Firstly,MWCNTs were covalently functionalized with mixture acid?HNO3/H2SO4,V/V=1:3?,and a novel 8-OHdG sensor was constructed based on MWCNTs modified glassy carbon electrode?GCE?.The fabricated sensor exhibited excellent electrochemical responses toward the oxidation of 8-OHdG,and the linear ranges were 5.63×10-8-6.08×10-6 M and 6.08×10-6-1.64×10-5 M,with the detection limit of 1.88×10-8 M?S/N=3?.Then,it was applied for the determination of 8-OHdG generated from damaged DNA and guanine,respectively,and the oxidation currents of 8-OHdG increased along with the damaged DNA and guanine within certain concentrations.These results could be used to evaluate the DNA damage,and provide useful information on diagnosing diseases caused by mutation and deficiency of the immunity system.2.In this section,MWCNTs were non-covalently functionalized with an aromatic organic perylene dye,3,4,9,10-Perylene tetracarboxylic acid?PTCA?,which could improve the specific surface area and conductivity of MWCNTs.Then a novel and facile electrochemical sensor for the simultaneous detection of adenine?A?and guanine?G?was fabricated based on PTCA-MWCNTs composites.It exhibited good electrochemical responses toward the oxidation of A and G with a linear ranges covering 1.74×10-7 M-2.09×10-5 M and 7.59×10-8-2.09×10-5 M,and the corresponding detection limit of 5.8×10-8 M and 2.53×10-8?S/N=3?,respectively.Moreover,the fabricated sensor was employed for the exploration the possible electrochemical reaction mechanism of G supported by cyclic voltammetry experiments?CV?.Eventually,the proposed sensor was applied successfully in the determination of A and G contents in calf thymus DNA with satisfactory results,which has the great potential application in the sensitive monitoring of electroactive bio-molecules. |
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