Using Tunable Nanoscale Confinement to Image and Manipulate DNA

Abstract

We present a modular microscopy device that transforms a basic inverted fluorescence microscope into a versatile single-molecule imaging and diagnostic system, with applications in the biomedical, biophysical and materials sciences. The device employs a recently developed and accessible imaging approach, Convex Lens- Induced Confinement (CLIC), delivering key advantages based on its tunable nanoscale imaging geometry: sensitive detection and enhanced background suppression; minimal required analyte volume (~μL); direct visualization of molecular interactions and dynamics over extended time periods (seconds to minutes); and direct manipulation of molecular conformations [1]. The presented CLIC device loads the sample into a flow-cell using a microfluidics system and mechanically deforms the flow-cell, creating a tunable, nanoscale imaging chamber. A powerful feature of CLIC imaging is the ability to manipulate and visualize single molecules under a continuum of applied confinement, from the micrometer to nanometer scale. It overcomes a key challenge faced by existing nanofluidic technologies of delivering molecules from a microscale loading environment into a nanoscale imaging environment. We demonstrate the device’s ability to manipulate the conformations of DNA molecules in free-solution, providing a new approach to partitioning and probing their physical properties. Further, combining CLIC imaging with surface-lithography presents a powerful approach to controllably manipulating and trapping molecules over a wide range of imaging conditions.