Font Size: a A A

CNTs-DNA Biosensor Built By Self-Assembly And The Research On Electrochemical Characterstics

Posted on:2009-10-22Degree:MasterType:Thesis
Country:ChinaCandidate:J LiFull Text:PDF
GTID:2178360272473974Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
The DNA biosensor based on carbon nanotubes(CNTs) possess both the excellent electricity of CNTs and the self- identification of DNA, and it exhibits preferable efficiency in the fields of biological detecting, diagnosis, electrochemistry detecting and many others. In the paper, The multi-walled carbon nanotube(MWNTs)-DNA biosensor was built by self-assembly. The electrochemistry of MWNTs-DNA biosensor was detected and the detect to hydroquinone was discussed primarily.First, the MWNTs were functionalized by the mixture of H2SO4 and HNO3, FTIR spectra suggests that carboxylic acid groups were introduced on the surfaces of the nanotubes. Then in the presence of 1-Ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxy- succinimide (NHS), the carboxylic MWNTs were assembled on amine-modified platinum electrode surface and followed by the assembly of NH2-DNA with the carboxyl–amine coupling , respectively. Fourier transform infrared(FTIR) demonstrated that NH2-DNA formed covalent amino bonds with the COOH- MWNTs. Atomic force microscopy (AFM) and Field emission electron microscopy (FEG-SEM) indicating that the MWNTS had been organized on amine-modified Pt electrode surface and DNA are assembled on the MWNTs, forming self-assembled momolayers with orderly orientation and uniform structure.Cyclic voltammetry was used to detect the electrochemistry of MWNTs-DNA biosensor and Fe(CN)64-/ Fe(CN)63- was selected as indicator for their cyclic voltammetric responses. The result indicateing the MWNTs-DNA biosensor has good stability. When the scan rate was increased, the oxidation peak shifted to positive electrode and reduction peak currents shifted to negative electrode, the peak currents are proportional to the square root of the scan rate, indicating a surface-controlled redox process and a diffusion controlled mechanism.Finally, we used the MWNTs-DNA biosensor to detect hydroquinones in PH 7.30 normal saline phosphate buffer solution, cylic voltammetry and ultraviolet-visble spectrophotometry were chosed. The result shows that the peaks and the intension of absorption of ultraviolet-visible spectra in hybridization changed obviously, the oxidated peak of cyclic voltammetry shifted to positive and the peak currents decreased. This fact signified that the electrostatic attraction andΠ-Πbanding between hydroquinones and DNA are the major modes for the interaction in hybridization.
Keywords/Search Tags:Carbon nanotube, DNA, Self-assembly, Biosensor, Hydroquinone, Cylic voltammetry
PDF Full Text Request
Related items