Stanford
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Docket #: S04-213

Trapping Nanoscale Objects in Solution

W.E. Moerner and Adam Cohen have patented the Anti-Brownian ELectrokinetic trap (ABEL trap) which can trap, measure, and manipulate sub-micron objects (e.g. single molecules) in solution at ambient temperature. The ABEL trap uses high-speed fluorescence microscopy to track the Brownian motion of a single fluorescent molecule. A feedback circuit applies carefully timed electric fields to the solution to induce an electrokinetic drift that cancels the Brownian motion. The ABEL trap is non-invasive, gentle, and can trap objects far smaller than can be trapped with laser tweezers. Applications include precise single-molecule measurements and nanomanfacturing.

News article - "Building a Better Molecule Trap", Science, Feb. 18 2005.

Figure



Figure description - Trapping region of the ABEL trap showing biomolecules in a microfluidic cell

Stage of Research

  • Proof-of-principle device trapped fluorescent polystyrene nanospheres with diameters down to 20 nm.
  • The ABEL trap was used to examine the photophysics of a single fluorescent protein, allophycocyanin (APC), the bacterial light-harvesting complex LH2, and the enzymatic behavior of single nitrite reductase enzymes. The technique allowed the observation of single molecules of solution-phase biomolecules for more than one second. The trap allows simultaneous measurement of brightness, excited state lifetime, and emission spectrum of the trapped object.
  • The trap has been developed extensively to trap ever smaller objects, down to the ultimate limit of one single fluorescent molecule.
  • The trapping algorithm and analysis have been extensively refined to allow real-time estimation of the diffusion coefficient and the electrokinetic mobility of the object, which enable binding and association events to be sensed.

    • Applications

    • Research tool for studying single molecules
      • Nanomanipulation of objects in microfluidics
      • Identification of biological particles and nanoparticles
      • Single-molecule spectroscopy
      • Sorting of individual proteins
      • Photodynamics
      • Association and binding events
    • Nanomanufacturing
    • Studying bacterial photosynthetic regulation and biomaterials for solar energy harvesting

    Advantages

    • Traps sub-micron objects then can position the object with nanoscale resolution
    • Can trap any object that can be imaged optically and that can be dissolved in non-corrosive solvent (e.g. water)
    • Provides real-time information on fluorescence intensity, excited state lifetime, emission spectrusm, mobility, drag coefficient, and charge of a single nanoscale object
    • Non-invasive, non-destructive
    • Gentler than laser tweezers
    • Scales more favorably for small objects than laser tweezers

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