A simple and sensitive impedimetric aptasensor for the detection of tumor markers based on gold nanoparticles signal amplification.

A simple and sensitive electrochemical impedimetric aptasensor based on gold nanoparticles (AuNPs) signal amplification was developed for the ultrasensitive detection of tumor markers (mucin 1 protein, MUC1 as a model). The designed cDNA, which is partly complementary with the aptamer of MUC1 was immobilized on the gold electrode. The detection of MUC1 could be carried out by virtue of switching structures of aptamers from DNA/DNA duplex to DNA/target complex. The change of the interfacial feature of the electrode was characterized by electrochemical impedance analysis (EIS) with the redox probe [Fe(CN)6](3-/4-). The quantitative detection of MUC1 protein was obtained from the changes of electron-transfer resistance (ΔRet). Moreover, as the signal enhancer, the aptamer-modified AuNPs (Apt@AuNPs) conjugates was introduced on the electrode by the hybridization of cDNA with aptamer. As expected, the detection sensitivity for MUC1 was greatly improved, which may be due to the specific binding of MUC1 onto the surface of the Apt@AuNPs modified electrode. This proposed simple aptasensor has a low detection limit of 0.1 nM, and also exhibits several advantages of high sensitivity and good selectivity. This present work may provide a general model for the detection of tumor marker based on impedimetric aptasensor.