Bionic catalysis of porphyrin for electrochemical detection of nucleic acids

A novel electrochemical strategy was designed for the detection of DNA based on the bionic catalysis of porphyrin. The detection probe was prepared via the assembly of thiolated double strand DNA (dsDNA) with gold nanoparticles (AuNPs), and then interacted with cationic iron (III) meso-tetrakis (N-methylphyridinum-4-yl) porphyrin (FeTMPyP) via groove binding along the dsDNA surface. The resulting nanocomplex was characterized with transmission electron microscopy, UV–vis absorption and circular dichroism spectroscopy. The FeTMPyP–DNA–AuNPs probe on gold electrode demonstrated the excellent electrocatalytic behaviors toward the reduction of O2 due to the largely loading of FeTMPyP and good conductivity. Based on bionic catalysis of porphyrin for the reduction of O2, the resulting biosensor exhibited a good performance for the detection of DNA with a wide linear range from 1 × 10−12 to 1 × 10−8 mol L−1 and detection limit of 2.5 × 10−13 mol L−1 at the signal/noise of 3. More importantly, the biosensor presented excellent ability to discriminate the perfectly complementary target and the mismatched stand. This strategy could be conveniently extended for detection of other biomolecules. To the best of our knowledge, this is the first application of bionic catalysis of porphyrin as detection probe and opens new opportunities for sensitive detection of biorecognition events.

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► This is the first application of bionic catalysis of porphyrin as detection probe in bioanalysis.
► Porphyrin–DNA–gold nanoparticle probe is synthesized.
► Binding model between FeTMPyP and DNA is verified.
► The detection probe shows excellent electrocatalytic behaviors toward the reduction of O2.
► The biosensor exhibited good performance with wide linear range and high specificity.