Strategy for polychlorinated biphenyl detection based on specific inhibition of charge transport using a nanogapped gold particle film.

A new strategy to detection of polychlorinated biphenyls (PCBs) using an electrical nanogap device is presented. This strategy is based on specific inhibition of charge transport when PCBs are captured by the cavities of β-cyclodextrin (β-CD) that are modified onto gold nanogapped electrodes' surfaces. The binding of PCBs to the cavities of β-CD leads to readily measurable conductivity decreases associated with the formation of guest-host complexes. PCB-29, PCB-77, PCB-101, PCB-153, and PCB-187 were chosen for the experiments. Six persistent organic pollutants, substituted benzenes with different sizes-1,2-dichlorobenzene, 1,4-dichlorobenzene, p-nitrophenol, 2,4-dichlorophenol, 1,3,5-trichlorobenzene, 1,2,4,5-tetrachlorobenzene-were chosen to investigate the selectivity properties of the nanogap devices. A modified "thermionic emission" electron tunneling model is used to account for the mechanisms for "inhibition of charge transport". We believe that this specific inhibition of charge transport in a electrical nanogap device provides a promising approach to detect those pollutants having chemical inertness and insulating properties in the environment.