Figure 4

Comparison of platinum coated and uncoated sample preparations critical point dried BoFeN1 bacteria in both the HIM and FE-SEM at low and high magnifications.

(a) Low and high magnifications of platinum coated (using an Everhart-Thornley (E-T) detector) and (b) uncoated bacterium (using an In-Lens (I-L) detector) in the FE-SEM reveal Fe(III) platelet structures that were on the order of tens of nanometers in size. Although the structures appeared much more flat in the uncoated sample, resolution was limited due to the necessity to use low-voltage imaging. (c) Low and high magnifications of platinum coated and (d) uncoated bacterium in the HIM reveal the coating induced artifact of globular structures and artificial textures on the platelets. The uncoated platelets in the HIM were for the first time revealed to be relatively flat with relatively sharp-tipped cellular attachments. Scale bars: 250 nm.