Gold nanoparticles modified electrode via simple electrografting of in situ generated mercaptophenyl diazonium cations for development of DNA electrochemical biosensor

A novel protocol for development of DNA electrochemical biosensor based on gold nanoparticles (AuNPs) modified glassy carbon electrode (GCE) was proposed, which was carried out by the self-assembly of AuNPs on the mercaptophenyl film (MPF) via simple electrografting of in situ generated mercaptophenyl diazonium cations. The resulting MPF was covalently immobilized on GCE surface via C–C bond with high stability, which was desirable in fabrication of excellent performance biosensors. Probe DNA was self-assembled on AuNPs through the well-known Au–thiol binding. The recognition of fabricated DNA electrochemical biosensor toward complementary single-stranded DNA was determined by differential pulse voltammetry with the use of Co(phen) 3 3+ as the electrochemical indicator. Taking advantage of amplification effects of AuNPs and stability of MPF, the developed biosensor could detect target DNA with the detection limit of 7.2 × 10 −11 M, which also exhibits good selectivity, stability and regeneration ability for DNA detection.