Graphene-PAMAM dendrimer-gold nanoparticle composite for electrochemical DNA hybridization detection.

Graphene oxide is chemically functionalized using planar structured first generation polyamidoamine dendrimer (G1PAMAM) to form graphene core GG1PAMAM. The monolayer of GG1PAMAM is anchored on the 3-mercapto propionic acid monolayer pre-immobilized onto a gold transducer. The GG1PAMAM is decorated using gold nanoparticles for the covalent attachment of single-stranded DNA through simple gold-thiol chemistry. The single- and double-stranded DNAs are discriminated electrochemically in the presence of redox probe K3[Fe(CN)6]. Double-stranded-specific intercalator methylene blue is used to enhance the lower detection limit. The use of linear and planar G1PAMAM along with the graphene core has enhanced the detection limit 100 times higher than the G1PAMAM with the conventional ethylene core. This chapter presents the details of GG1PAMAM preparation and application to DNA sensing by electrochemical methods.