Sensing force and charge at the nanoscale with a single-molecule tether

Abstract

Measuring the electrophoretic mobility of molecules is a powerful experimental approach for investigating biomolecular processes. A frequent challenge in the context of single-particle measurements is throughput, limiting the obtainable statistics. Here, we present a molecular force sensor and charge detector based on parallelised imaging and tracking of tethered double-stranded DNA functionalised with charged nanoparticles interacting with an externally applied electric field. Tracking the position of the tethered particle with simultaneous nanometre precision and microsecond temporal resolution allows us to detect and quantify electrophoretic forces down to the sub-piconewton scale. Furthermore, we demonstrate that this approach is capable of detecting changes to the particle charge state, as induced by the addition of charged biomolecules or changes to pH. Our approach provides an alternative route to studying structural and charge dynamics at the single-molecule level.

arXiv comment23 pages, 7 figures

References in corpus (5)

• Theory of High-Force DNA Stretching and Overstretching
• Excluded-Volume Effects in Tethered-Particle Experiments: Bead Size Matters
• Concentration and Length Dependence of DNA Looping in Transcriptional Regulation
• Massively parallel single-molecule manipulation using centrifugal force
• Probing DNA conformational changes with high temporal resolution by Tethered Particle Motion