Amplified electrochemical DNA sensor based on hemin/G-quadruplex DNAzyme as electrocatalyst at gold particles modified heated gold disk electrode

• A heated gold particles modified gold disk electrode (Au-HAuDE) was fabricated.
• HRP-DNAzyme as signal label for DNA detection at Au-HAuDE was realized.
• With elevated electrode temperature, the detection limit was greatly improved.
• This method can easily be extended to other biological molecule measurements.

A new method for electrochemical detection of DNA hybridization with elevated electrode temperature at gold particles modified heated gold disk electrode (Au-HAuDE) is demonstrated. This method employs a hairpin DNA probe for target DNA capture and incorporates a specific DNAzyme sequence into the probe as electrocatalytic label. The hairpin DNA probes are immobilized on the Au-HAuDE. The presence of target DNA opens the hairpin structure, releases the DNAzyme sequence, and forms the hemin/G-quadruplex peroxidase-mimicking DNAzyme (HRP-DNAzyme) with hemin addition. With elevated electrode temperature, the electrocatalytic activity of HRP-DNAzyme for H2O2 reduction by oxidation of hydroquinone (used as an electron transfer mediator) can be significantly improved, resulting in an enhanced electrochemical reduction current of benzoquinone for DNA detection. With an electrode temperature of 50 °C, the detection limit for target DNA measurements can be decreased ca. one magnitude compared with that at 0 °C.

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