Label-free detection of the aptamer binding on protein patterns using Kelvin probe force microscopy (KPFM)

Anal Bioanal Chem. 2009 May;394(1):207-14. doi: 10.1007/s00216-008-2577-8. Epub 2009 Jan 16.


Anti-lysozyme aptamers are found to preferentially bind to the edge of a tightly packed lysozyme pattern. Such edge-binding is due to the better accessibility and flexibility of the edge lysozyme molecules. Kelvin probe force microscopy (KPFM) was used to study the aptamer-lysozyme binding. Our results show that KPFM is capable of detecting the aptamer-protein binding down to the 30 nm scale. The surface potential of the aptamer-lysozyme complex is approximately 12 mV lower than that of the lysozyme. The surface potential images of the aptamer-bound lysozyme patterns have the characteristic shoulder steps around the pattern edge, which is much wider than that of a clean lysozyme pattern. These results demonstrate the potentials of KPFM as a label-free method for the detection of protein-DNA interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aptamers, Nucleotide / analysis*
  • Aptamers, Nucleotide / chemistry
  • Aptamers, Nucleotide / metabolism*
  • Binding Sites
  • Microscopy, Scanning Probe / methods*
  • Muramidase / chemistry
  • Muramidase / metabolism*
  • Sensitivity and Specificity
  • Staining and Labeling
  • Surface Properties


  • Aptamers, Nucleotide
  • Muramidase