Gold nanoparticles modified electrode via a mercapto-diazoaminobenzene monolayer and its development in DNA electrochemical biosensor.

A novel protocol for the gold nanoparticles (AuNPs) modification on the electrode surface was proposed, which was based on the self-assembly of AuNPs on the mercapto-diazoaminobenzene monolayer modified electrode. The mercapto-diazoaminobenzene monolayer was obtained by covalent immobilization of 4-aminothiophenol (4-ATP) molecules onto another 4-ATP monolayer functionalized gold electrode by diazotization-coupling reaction. The DNA immobilization and hybridization on the AuNPs modified electrode was further investigated. The prepared AuNPs-ATP-diazo-ATP film demonstrated efficient electron transfer ability for the electroactive species toward the electrode surface due to a large conjugated structure of the mercapto-diazoaminobenzene monolayer. The recognition of fabricated electrochemical DNA biosensor toward complementary single-stranded DNA was determined by differential pulse voltammetry with the use of Co(phen)(3)3+ as an electrochemical indicator. A linear detection range for the complementary target DNA was obtained from 3.01 x 10(-10) to 1.32 x 10(-8) M with a detection limit of 9.10 x 10(-11) M. The fabricated biosensor also possessed good selectivity and could be regenerated easily.