Study On Electrochemical Biosensors Based On Low Dimensional Nanocarbon Materials

[133] Fahlman R P, Sen D J. DNA Conformational Switches as Sensitive Electronic Sensors of Analytes. Journal of the American Chemical Society, 2002, 124(17): 4610-4616[134] Steel A B, Levicky R L, Herne T M, et al. Immobilization of Nucleic Acids at Solid Surfaces: Effect of Oligonucleotide Length on Layer Assembly. Biophysical Journal, 2000, 79(2): 975-981 a PdNPs/CSGR-based nanocomposite film and demonstrateed its application for sensitive glucose sensing (in chapter 3).(3)We exploited single-stranded-DNA-wrapped CNTs as the electrochemical labels for the magnetic separation-based DNA hybridization assay. In this method, the noncovalent wrapping of CNTs with single-stranded DNA via hydrophobic andπ-πstacking interactions not only imparts aqueous solubility and stability of CNTs but also allows a further molecular recognition reaction between the DNA onto the CNTs and the target DNA. Moreover, in order to enhance the discrimination capability for the single base mismatch, the magnetic beads were modified with the hairpin DNA. When the probes hybridized with the target nucleic acid, the allostery of the hairpin DNA on the MBs surface was switched and the ssDNA-wrapped CNTs labels were selectively collected by magnetic separation-based DNA hybridization reaction. With the assembly of these electrochemical labels on the C18H37SH-blocked electrode surface, a strong redox current was obtained. The developed strategy could quantitatively determine the target DNA in the dynamic range of 1 pM ~ 500 nM with the detection limit of 0.9 pM. The present approach has been demonstrated with the identification of a single base mutation in Hepatitis B virus specific sequence, and the wild type and mutant type were successfully scored (in chapter 4).