Electrical modes of Atomic Force Microscopy (AFM) allow the high-resolution mapping of surface charges on a sample with nanometer precision. A particular measurement challenge is to perform such modes on biological samples (tissue extracts, biomolecules, biomembranes, etc). To this end, the project aims to investigate different preparation and measurement approaches and a specific goal is to determine alterations of surface charge of biological fibers caused by the reaction with sugar, which has important implications in medicine and cell biology.

Surface potential map from Kelvin Probe Force Microscopy (KFM), showing voltage values between –0.79 V and –0.61 V across a 4 µm × 4 µm scan area.

Fig. 1 KFM surface potential map of a collagen fibril on graphite. The bright spots show areas of positive charge.

Project focus

  • Determine the influence of humidity on ionised, chemical surface groups
  • Investigate the charge of glycated protein fibrils

Project partners/collaborators

Publications

  • Kohl, D., P. Mesquida and G. Schitter (2017). „Quantitative AC – Kelvin Probe Force Microscopy.“ Microelectronic Engineering 176: 28-32.
  • P.Mesquida, D.Kohl, O.G.Andriotis, P.J.Thurner, M.J.Duer, S.B.Bansode, G.Schitter, Kelvin-probe Force Microscopy to map glycation of proteins, AFM Biomed Conference, Krakow 2017.