Single unlabeled protein detection on individual plasmonic nanoparticles

Nano Lett. 2012 Feb 8;12(2):1092-5. doi: 10.1021/nl204496g. Epub 2012 Jan 31.


The ultimate detection limit in analytic chemistry and biology is the single molecule. Commonly, fluorescent dye labels or enzymatic amplification are employed. This requires additional labeling of the analyte, which modifies the species under investigation and therefore influences biological processes. Here, we utilize single gold nanoparticles to detect single unlabeled proteins with extremely high temporal resolution. This allows for monitoring the dynamic evolution of a single protein binding event on a millisecond time scale. The technique even resolves equilibrium coverage fluctuations, opening a window into Brownian dynamics of unlabeled macromolecules. Therefore, our method enables the study of protein folding dynamics, protein adsorption processes, and kinetics as well as nonequilibrium soft matter dynamics on the single molecule level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Gold / chemistry*
  • Kinetics
  • Metal Nanoparticles / chemistry*
  • Nanotechnology
  • Protein Folding
  • Proteins / analysis*
  • Surface Plasmon Resonance
  • Surface Properties


  • Proteins
  • Gold