(381d) Salt Gradient Regulation of Ion and Nanoparticle Transport in Nanopores with Bipolar Charges

Fundamental understanding of ion and nanoparticle (NP) transport is crucial for designing nanofluidic/nanopore devices and characterizing individual unlabeled (bio)nanoparticles. To enhance the resolution in the nanopore-based sensing device, two critical challenges need to be resolved, including enhance capture rate of NP and reduce simultaneously its translocation velocity through a nanopore. To achieve these, two types of bipolar nanopore, namely, only the inner surface (case I) and both the inner and outer surfaces (case II) of the nanopore with bipolar charges, are investigated. Results show that the ion current rectification (ICR) can be significantly regulated by a salt concentration gradient and even a reversed trend is observed when the salt gradient is large enough. Furthermore, we demonstrate that NP can be controlled effiecently in the bipolar nanopores. The simulation results gathered suggest that applying a salt gradient to a case I nanopore has the potential in single molecules sensing because it is capable of raising both the capture efficiency and the sensing resolution.