Optical trapping of a single protein

Nano Lett. 2012 Jan 11;12(1):402-6. doi: 10.1021/nl203719v. Epub 2011 Dec 16.


We experimentally demonstrate the optical trapping of a single bovine serum albumin (BSA) molecule that has a hydrodynamic radius of 3.4 nm, using a double-nanohole in an Au film. The strong optical force in the trap not only stably traps the protein molecule but also unfolds it. The unfolding of the BSA is confirmed by experiments with changing optical power and with changing solution pH. The detection of the trapping event has a signal-to-noise ratio of 33, which shows that the setup is extremely sensitive to detect the presence of a protein, even at the single molecule level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Optical Tweezers*
  • Protein Denaturation
  • Protein Folding
  • Serum Albumin, Bovine / isolation & purification*
  • Serum Albumin, Bovine / ultrastructure*


  • Serum Albumin, Bovine