A New Atomic Force Microscopy Technique for the Measurement of the Elastic Properties of Biological Materials

We developed a new technique to measure elastic properties by using the atomic force microscope (AFM) tip to press samples into grooves etched in a GaAs substrate. We measured the Young\u27s modulus of β-chitin fibres with cross-sections less than 40 nm X 20 nm to be 1-2 X 1011 N/m2. In the isotropic approximation, the Young\u27s modulus of the S-layer sheath of the archaeobacterium Methanospirillum hungatei was 1-3 X 1010 N/m2. By testing the sheath to breaking strength we estimated the bacterium can sustain an internal pressure as high as 100-200 atmospheres (1-2 x 107 N/m2)