Self-assembled multilayer of gold nanoparticles for amplified electrochemical detection of cytochrome c.

Although different kinds of film materials and some modification techniques are applied for the development of protein-film electrochemistry, the design of a more ordered adsorption platform with improved sensitivity is still required. Here we employ single-strand DNA (ssDNA)-functionalized gold nanoparticles as scaffolds for the construction of a multilayered uniform self-assembled structure via the hybridization of complementary ssDNA. After adsorbing with native conformation onto the uniformly built electrode, cytochrome c responded very well in voltammetry experiments. The peak currents increase with the addition of the number of gold nanoparticle layers, which indicates that the multilayer gold nanoparticles not only provide a compatible microenvironment for the protein to undergo direct electron transfer reactions but also amplify the electrochemical signals by increasing the binding sites for the protein immobilization. Furthermore, ultra-sensitive detection of cytochrome c by using this multilayer gold nanoparticle-modified electrode is carried out. The linear range is from 2 x 10(-9) to 1 x 10(-7) M with a detection limit of 6.7 x 10(-10) M.