FORCE MICROSCOPY ON LIVING CELLS

We have developed an underwater atomic force microscope (AFM) based on detection by tunneling for investigations of single living cells. The AFM setup allows compensation of the electrochemical potentials involved and is integrated into a high magnification optical microscope. Small living cells are sucked onto a microcapillary and are brought into contact with a cantilever for imaging. The cells are kept alive under appropriate physiological conditions while maintaining high resolution to image their molecular structures. For the first time, images of red blood cells made under these conditions with resolution down to about 10 nm are shown. In addition, changes induced by higher salt concentration and by the sticking of antibodies to the cell surface were observed. This indicates the wide range of possibilities of this method for studying dynamical processes of living organisms in situ with high spatial resolution.