Optical imaging of single-protein size, charge, mobility, and binding

Nat Commun. 2020 Sep 21;11(1):4768. doi: 10.1038/s41467-020-18547-w.


Detection and identification of proteins are typically achieved by analyzing protein size, charge, mobility and binding to antibodies, which are critical for biomedical research and disease diagnosis and treatment. Despite the importance, measuring these quantities with one technology and at the single-molecule level has not been possible. Here we tether a protein to a surface with a flexible polymer, drive it into oscillation with an electric field, and image the oscillation with a near field optical imaging method, from which we determine the size, charge, and mobility of the protein. We also measure antibody binding and conformation changes in the protein. The work demonstrates a capability for comprehensive protein analysis and precision protein biomarker detection at the single molecule level.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fourier Analysis
  • Ligands
  • Polyethylene Glycols / chemistry
  • Protein Binding
  • Protein Conformation
  • Proteins / chemistry*
  • Proteins / metabolism*
  • Single Molecule Imaging / methods*
  • Static Electricity
  • Tin Compounds / chemistry


  • Ligands
  • Proteins
  • Tin Compounds
  • Polyethylene Glycols
  • indium tin oxide