Transmission electron microscopy (TEM) imaging was performed using a JEOL 1400 electron microscope operating at 120 kV and equipped with a AMT XR611 CCD camera. Samples for TEM were prepared using a modified procedure from Paravastu et al. A 5 µL aliquot of sample was placed on freshly glow discharged carbon-coated grid and incubated for 2 min. The grid was then washed 5× with water and was then wicked dry with filter paper. The samples were stained after incubation for 2 min using 3 % (w/v) uranyl acetate. The excess stain was removed by blotting with filter paper and the grids were air dried in a dust free environment.