High Resolution AFM in Liquid

Using frequency modulation atomic force microscopy (FM-AFM) it is possible to routinely image surfaces with atomic resolution. However, until recently this was only achievable in ultra high vacuum, rendering it impossible to study biological samples in physiologically relevant environments with comparable resolution. The structure and function of biological molecules are extremely dependent on their hydration state, so it was important to extend FM-AFM to liquids in order to access the sensitivity and resolution necessary to elucidate the function of a broad range of biological systems. Our custom-built low noise AFM with a lateral resolution of 0.09 nm gives us the opportunity to study biological surfaces with submolecular resolution. At the moment this is the only method available to explore biological systems at this resolution in physiological environments.

In addition to imaging, AFM is capable of measuring the forces of interaction between the AFM tip and the surface. The high sensitivity of FM-AFM allows us to measure forces as low as a few piconewtons. At the moment, this is not possible with any commercially available AFMs and the force sensitivity is comparable with optical tweezers.

References

  1. Local Solvation Shell Measurement in Water Using a Carbon Nanotube Probe, Jarvis, S. P., Uchihashi, T., Ishida, T., Tokumoto, H., and Nakayama, Y., Journal of Physical Chemistry B, 104, 6091-6094, (2000).

  2. Development of Liquid-Environment Frequency Modulation Atomic Force Microscope with Low Noise Deflection Sensor for Cantilevers of Various Dimensions , Fukuma, T., and Jarvis, S. P., Review of Scientific Instruments, 77, 043701, (2006).

  3. Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy, Fukuma, T., Higgins, M. J., and Jarvis, S. P., Physical Review Letters, 98, 106101, (2007). [PDF]

  4. Direct Imaging of Individual Intrinsic Hydration Layers on Lipid Bilayers at Ångstrom Resolution, Fukuma, T., Higgins, M. J., and Jarvis, S. P., Biophysical Journal, 92, 3603-3609, (2007). 

  5. Revealing molecular-level surface structure of amyloid fibrils by frequency modulation atomic force microscopy in liquid, Fukuma, T., Mostaert, A. S., Serpell, L. C., and Jarvis, S. P., Nanotechnology, 19, 384010, (2008).

  6. Visualization of Ion Distribution at the Mica-Electrolyte Interface, Loh, S. H. and Jarvis, S. P., Langmuir, 26, 12, 9176 - 9178, (2010).

  7. Direct Submolecular Scale Imaging of Mesoscale Molecular Order in Supported Dipalmitoylphosphatidylcholine Bilayers, Sheikh, K. H., Giordani, C., Kilpatrick, J. I., Jarvis S. P., Langmuir, 27, 7, 3749-3753, (2011).

  8. Direct imaging of salt effects on lipid bilayer ordering at sub-molecular resolution, Ferber, U. M., Kaggwa, G. B., Jarvis, S. P., European Biophysics Journal, 40, 3, 329-338, (2011).