Imaging Molecules and Cells with the Atomic Force Microscope

Abstract

The atomic force microscope (AFM) gives topographic images by scanning a sharp stylus over a surface. The stylus is attached to a spring lever which is deflected when the stylus interacts with the surface. The AFM images a surface by measuring deflection as a function of position over the surface. The AFM has given atomic resolution images of both conductors and nonconductors. The AFM has also given images of amino acid polymers with subnanometer resolution. The AFM has imaged samples covered with a liquid and biological processes like blood clotting have been imaged. In this report we present several images that demonstrate the variety of samples that can be imaged with the AFM.The AFM has imaged adsorbed molecules at subnanometer resolution. Figure 1A is an image of the bare (010) surface of the natural zeolite, clinoptilolite. Molecules of t-butanol were then adsorbed onto the surface from the liquid and the sample was imaged again (Fig. IB).Figure 2 is an image of double stranded DNA dried onto mica. The resolution is sufficient to reveal corrugation due to the major groove of the double helix. We are currently working to gain resolution sufficient to sequence single-stranded DNA.