Electrochemical detection of DNA mismatches using a branch-shaped hierarchical SWNT-DNA nano-hybrid bioelectrode.

Common approaches for DNA mutation detection are high cost and have difficult or complex procedure. We propose a fast quantitative method for recognition of DNA mutation based on SWNT/DNA self-assembled nanostructure. Covalent SWNT/DNA hybrid nanostructures are widely used in the fabrication of electrochemical biosensors. Interfacing carbon nanotubes with DNA in particular, is used as a detection method for the analysis of genetic disorders or the detection of mismatches in DNA hybridisation. We have designed a self-assembled, branch-shaped hybrid nanostructure by hybridisation of two sticky oligos that are attached to the ends of SWNTs via a linker oligo. These hybrid nanostructures showed a good conductivity that was greater than free SWNTs. Impedance spectroscopy studies illustrated that the conductivity of these hybrid nanostructures depended on the conformation and structure of the hybridised DNA. We demonstrated that the strategy of using SWNT/DNA self-assembled hybrid nanostructure fabrication yields sensitive and selective tools to discriminate mismatches in DNA. Cyclic voltammetry (CV) and impedance spectroscopy clearly revealed that the conductivity of the branch-shaped and hierarchical hybridised SWNT/DNA nanostructure is higher when matched, than when mismatched in a 1 and 1' hybridised SWNT/DNA nanostructure. Rapid biosensing of match and mismatch nanostructure based on carbon printed electrode showed similar results which can be used for rapid and fast detection of DNA mismatch.