Haydon Lab Interests

Biological microscopists have long dreamed of being able to image individual molecules within the living cell. While this is still not yet possible, advances in the physical sciences with scanning probe microscopy have permitted scientists to make significant strides towards carrying out higher resolution imaging. Near-Field Optical Microscopy can permit optical resolution down to about 20-50 nm. However, it has been difficult to achieve such resolution in living systems. We have recently made further developments in this type of optical microscopy, including a patented approach, which we term 'Biological Near-Field Microscopy' (BNFM). Using BNFM we have achieved optical resolution down to 50 nm on hydrated samples where we have imaged actin filaments in isolated glial cells of the nervous system. We are now working with this technique in living cells to study the microdomains of calcium beneath individual calcium channels, and to resolve single vesicles in isolated nerve terminals.

Fiber-optic waveguides can be pulled to a fine aperture of the order of 20-100 nm in diameter. When coated with aluminum, the waveguides permit excitation light to exit only at the tip aperture. When a sample is placed in close proximity (the near-field) to the aperture, sub-diffraction optical resolution can be achieved. The figure at right is a photomicrograph taken using a conventional optical microscope and shows 488 nm light exiting from a near-field probe tip.