Electrophysiological study of Single gold nanoparticle/α-Hemolysin complex formation: A nanotool to slow down ssDNA through the α-Hemolysin nanopore

A method to trap single-monolayer-protected gold nanoparticles in the α-hemolysin (αHL) nanopore was reported. The method also demonstrated conductance signature of a single sodium 3-mercapto-1- propanesulfonate (MPSA)-coated gold nanocrystal trapped inside the αHL. The trans-membrane potential amplitude impact on the size of the nanoparticle inside the pore and correlation between the size of trapped nanoparticle and its dwell time were also reported. It was observed that the largest nanoparticle entered in the pore yielded a 50% block of the pore conductance. Gold nanoparticles coated with MPSA and mixtures of MPSA/octanethiol (OT) organic ligands were synthesized for the study. It was also found that the particles with small diameter were able to individually enter in αHL nanopore cavity when a potential was applied to accelerate the negatively charges nanoparticles.