Development of an electrochemical aptamer-based sensor with a sensitive Fe3O4 nanopaticle-redox tag for reagentless protein detection

A sensitive and reagentless electrochemical aptamer-based (E-AB) sensor for specific recognition of thrombin was developed based on the Fe3O4-nanoparticle(FNP)-tagged technique. The FNP-tagged aptasensor was fabricated with a bifunctional aptamer covalently linked by a FNP tag at 3′-terminus and self-assembled on the gold electrode at 5′-terminus, which were characterized by TEM, AFM, UV–Vis and electrochemical impedance spectra. Specific binding of thrombin with the aptamer on this aptasensor produced a redox signal and detected by differential pulse voltammetry, where FNP-tag could gain signal-amplification due to its containing more redox centers. The aptasensor showed a linear response for thrombin in the range of 1.0–75 nM, and a lower detection limit of 0.1 nM (at S/N = 3). The E-AB sensor was high sensitive and stable, and could be used to detect target protein at a clinic level in biological samples.

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► A reagentless aptasensor for specific recognition of thrombin was developed.
► Specific binding of thrombin with the aptamer on this aptasensor produced a redox signal.
► The Fe3O4-nanoparticle tag is sensitive and can gain signal-amplification.
► A detection limit of 0.1 nM for thrombin with desirable specificity, stability and sensitivity.
► The aptasensor can selectively detect the target protein in complex samples.