Abstract

Detection and Identification of Single Molecules using Nanoscale Electrophoresis and Resistive Pulse Sensing

Steve Soper, Foundation Distinguished Professor; Director, Center of BioModular Multi-scale System for Precision Medicine, Adjunct Professor, Ulsan National Institute of Science & Technology, The University of Kansas

We are generating a label-free single-molecule sensor that can detect and identify various molecules (small – ribonucleotides, deoxynucleotides, peptides – and large molecules – oligonucleotides, proteins) using a combination of nanoscale electrophoresis and resistive pulse sensing. The sensing technology employs a nanochannel to read the identity of individual molecules from their molecular-dependent electrophoretic mobility deduced from the travel of the molecule through a 2-dimensional (2D) nanochannel (~50 nm in width and depth; 5 – 10 µm in length) fabricated in a thermoplastic via nano-injection molding. The mold insert used for injection molding is made from a Si master that has undergone photolithography to build microstructures and focused ion beam milling to generate the nanostructures, which is used to produce resin stamps that serve as the mold insert. The 2D nanochannel is flanked on either end with an in-plane nanopore (effective diameter <10 nm) that can detect single molecules using resistive pulse sensing in a label free fashion. In this presentation, we will present our results using nanoscale electrophoresis to deduce the identity of deoxynucleotides, ribonucleotides, and peptides. The effect of material (type of plastic), scaling effects, and surface modifications of the 2D nanochannel on the performance of nanoscale electrophoresis will be discussed as well. We will also discuss the use of principle component analysis or machine learning to improve the identification accuracy of single molecules from not only their unique electrophoretic mobility, but also the molecular-dependent dwell time (current transient event width) and event amplitude generated from each in-plane pore. We will also discuss unique applications of this sensing platform including single-molecule DNA/RNA sequencing and protein fingerprinting using peptides produced from the solid-phase proteolytic digestion of single protein molecules.