Gold Nanoparticle Translocation Dynamics and Electrical Detection of Single Particle Diffusion Using Solid-State Nanopores

This paper describes the use of gold nanoparticles to study particle translocation dynamics through silicon nitride solid-state nanopores. Gold nanoparticles were dispersed in 20 mM KCl solution containing nonionic surfactant Triton X-100 and their translocation was studied at different applied voltages. The use of low electrolyte concentration resulted in current enhancement upon particle translocation. The counterion cloud around the nanoparticles is proposed to be the reason for current enhancement phenomena because associated counterion cloud is believed to increase the ion density inside the pore during particle translocation. Further, single particle diffusion events were also recorded at 0 mV voltage bias and 0 pA background ionic current with high signal-to-noise ratio as the particles moved down their concentration gradient. The ability of nanopore sensors to detect single particle diffusion can be extended to field-free analysis of biomolecules in their native state and at or near physiological salt concentrations.