Photothermal Transport of DNA in Entropy-Landscape Plasmonic Waveguides

Cameron Smith, Anil Haraksingh Thilsted, Jonas Nyvold Pedersen, Tomas Hugh Youngman, Julia C. Dyrnum, Nicolai A. Michaelsen, Rodolphe Marie, Anders Kristensen

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The ability to handle single, free molecules in lab-on-a-chip systems is key to the development of advanced biotechnologies. Entropic confinement offers passive control of polymers in nanofluidic systems by locally asserting a molecule's number of available conformation states through structured landscapes. Separately, a range of plasmonic configurations have demonstrated active manipulation of nano-objects by harnessing concentrated electric fields. The integration of these two independent techniques promises a range of sophisticated and complementary functions to handle, for example, DNA, but numerous difficulties, in particular, conflicting requirements of channel size, have prevented progress. Here, we show that metallic V-groove waveguides, embedded in fluidic nanoslits, form entropic potentials that trap and guide DNA molecules over well-defined routes while simultaneously promoting photothermal transport of DNA through the losses of plasmonic modes. The propulsive forces, assisted by in-coupling to propagating channel plasmon polaritons, extend along the V-grooves with a directed motion up to ≈0.5 μm·mW-1 away from the input beam and λ-DNA velocities reaching ≈0.2 μm·s-1·mW-1. The entropic trapping enables the V-grooves to be flexibly loaded and unloaded with DNA by variation of transverse fluid flow, a process that is selective to biopolymers versus fixed-shape objects and also allows the technique to address the challenges of nanoscale interaction volumes. Our self-aligning, light-driven actuator provides a convenient platform to filter, route, and manipulate individual molecules and may be realized wholly by wafer-scale fabrication suitable for parallelized investigation.
Original languageEnglish
JournalA C S Nano
Pages (from-to)4553-4563
Number of pages11
Publication statusPublished - 2017


  • V-groove
  • Channel plasmon polariton
  • Entropic trapping
  • Nanoconfined DNA
  • Nanofluidics
  • Photothermal effect


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