Elastic modulus of suspended purple membrane measured by atomic force microscopy

Ari M. Siitonen, Koji Sumitomo, Chandra S. Ramanujan, Youichi Shinozaki, Nahoko Kasai, Kazuaki Furukawa, John F. Ryan, Keiichi Torimitsu

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


We have probed the mechanical properties of purple membrane (PM) in a physiological environment using the atomic force microscope (AFM). By suspending PM over nano-trenches, the elastic properties of PM can be evaluated free from the interaction with the substrate. Force-displacement curves were obtained on the suspended membrane and the data was compared to that of a simple model of a thin film over a trench. By fitting the data to the model, the elastic modulus of PM was estimated to be 8 MPa. When the membrane is repeatedly indented, we observed a change in the force-distance data consistent with damage to the two-dimensional crystal of PM. In this paper we demonstrate that the AFM allows us to evaluate the mechanics of biological membranes in their native conditions.

Original languageEnglish
Pages (from-to)7877-7880
Number of pages4
JournalApplied Surface Science
Issue number23
Publication statusPublished - 2008 Sept 30


  • Elastic modulus
  • Membrane protein
  • Nanobiotechnology
  • Scanning probe microscopy


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