Electrochemical genosensor based on disc and screen printed gold electrodes for detection of specific DNA and RNA sequences derived from Avian Influenza Virus H5N1

• Miniaturized genosensor detects 1 pM of 20-mer DNA and 280-mer RNA sequences derived from H5N1.
• Genosensors discriminate between different positions of complementary sequence in RNA.
• Miniaturized genosensor has potential as device for early diagnosis of H5N1.

The genosensors based on thiolated ssDNA probe deposited on the two types of gold electrodes: screen-printed (miniaturized) and disc electrodes destined for determination of specific sequences of DNA and RNA derived from Avian Influenza Virus H5N1 have been proposed. The working principle of genosensor is based on the ion-channel mechanism. The analytical signals generated upon hybridization processes were recorded using electrochemical technique – Osteryoung square wave voltammetry in the presence of a redox active marker [Fe(CN)6]3−/4− in the sample solution. The miniaturized genosensor based on screen printed gold electrodes was able to detect the 20-mer complementary DNA oligonucleotide sequence as well as ∼280-mer RNA sequences containing the complementary 20-mer sequence in various positions: at 3′-terminus, at 5′-terminus and in the middle of the RNA transcript at the 1 pM concentration. The measuring systems were selective. Non-complementary 20-mer oligonucleotide sequence as well as RNA transcript without complementary region generated weak response. The RNA transcripts were also tested with gold disc electrodes modified in the same manner. This device was able to detect ∼280-mer RNA sequences, but at higher concentration of 10 pM. The good discrimination of the position of complementary part in the ∼280-mer RNA sequences was observed with using both types of modified electrodes.

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