Professor William M. Shih, Dana-Farber Cancer Institute, Department of Cancer Biology, Harvard Medical School and Wyss Institute, Harvard University, USA

Single-molecule detection and identification via DNA nanotechnology

Signal amplification via molecular polymerization has proven to be a powerful strategy for the detection of nucleic-acid biomarkers, however most approaches are constrained either by the need for external instrumentation or limited sensitivity due to properties intrinsic to the molecular system design. Here we expand crisscross polymerization, a strategy previously shown to achieve robustly seed-dependent self-assembly of single-stranded DNA and DNA-origami monomers, to achieve autonomous, isothermal exponential amplification of crisscross ribbons through their concurrent growth and scission via toehold-mediated strand displacement. We demonstrate how this CrissCross Chain Reaction, or 3CR, can be used as a detection strategy through coupling to single- and double-stranded nucleic-acid targets. In addition to discussing crisscross, I'll also describe our efforts towards single-protein identification via mechanical fingerprinting. We combine DNA nanotechnology with single-molecule force spectroscopy to create a mechanically reconfigurable DNA Nanoswitch Caliper capable of measuring multiple coordinates on single biomolecules with atomic resolution.