Self-assembled nanoparticle necklaces network showing single-electron switching at room temperature and biogating current by living microorganisms.

A network of one-dimensional (1D) Au nanoparticle necklaces is synthesized and shown to exhibit electronic switching, that is, gating, by the metabolic activity of yeast cells deposited on the structure. Without the cells, the network exhibits the Coulomb blockade effect at room temperature with a sharp threshold voltage, V(T) of approximately 0.45 V, which corresponds to a switching energy of approximately 20 kT. Although the enhancement in V(T) from approximately 70 mV for a single (10 nm) Au particle to >1 V is well-known for a 2D array, the uniqueness of the network topology is the relatively weak dependence of V(T) on temperature that leads to room temperature switching behavior, in contrast to an array where the blockade effect vanishes at ambient temperatures. The coupling between the biochemical process of the cell and the electronics of the network has potential applications for making electrodes for biofuel cells and highly sensitive biosensors using the cell as the specific sensing moiety.