DNA polymorphism sensitive impedimetric detection on gold-nanoislands modified electrodes

•Use of gold nanoparticles graphite–epoxy nanocomposite (nanoAu–GEC) in DNA analysis.•Hybrid platform permits the use of thiol coupling chemistry on a graphite electrode.•Electrochemical and microscopic characterization of developed platform.•Impedimetric detection of triple base mutation deletion of the cystic-fibrosis gene.•Limit of detection 2.25 fmol DNA polymorphism, rapidly and with low cost.

Nanocomposite materials are being increasingly used in biosensing applications as they can significantly improve biosensor performance. Here we report the use of a novel impedimetric genosensor based on gold nanoparticles graphite–epoxy nanocomposite (nanoAu–GEC) for the detection of triple base mutation deletion in a cystic-fibrosis (CF) related human DNA sequence. The developed platform consists of chemisorbing gold nano-islands surrounded by rigid, non-chemisorbing, and conducting graphite–epoxy composite. The ratio of the gold nanoparticles in the composite was carefully optimized by electrochemical and microscopy studies.Such platform allows the very fast and stable thiol immobilization of DNA probes on the gold islands, thus minimizing the steric and electrostatic repulsion among the DNA probes and improving the detection of DNA polymorphism down to 2.25 fmol by using electrochemical impedance spectroscopy. These findings are very important in order to develop new and renewable platforms to be used in point-of-care devices for the detection of biomolecules.

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