Team:FAU Erlangen/Results

iGEM Erlangen

Results

Figure 1: TEM images of ZnO microflowers related to syntheses by Zhang et al. (2004).




From the TEM images of the ZnO synthesis it could be concluded that no autoclave is needed to produce the microflowers, which was used by Zhang et al. (2004). The purpose using highly branched systems, is an increase of adsorbing molecules on the surface. Further, the branched ZnO clusters can be anchored more simply in a biofilm, than flat or spherical nanoplatelets. The size of the microflowers was a general problem for our proof of concept. As the particles could cover most of the distance from one electrode to the other. This implies that biofilm can be used as template to stabilize the structures, however it is no crucial factor. To circumvent this issue, we changed the procedure to a direct mineralization process, where the biofilm is directly involved in the synthesis on ZnO.



Figure 2: ZnO nanoparticles grown in presence (left) and absence of curli fibers (right) on a p-doped silica wafer

The REM images (Figure 1) visualize the difference between ZnO growth in presence and absence of curli fibers on the glass surface. In presence of curli, the particles tend to grow isotropically, with fibers coated around an assembly of individual particles. The ZnO nanoclusters provide average sizes of 0.9 µm with a standard deviation of 0.2 µm, considering 50 clusters. In absence of curli fibers, needle like structures form, which are highly uniform in shape with an average length of 1.1 µm and an average width of 0.55 µm. The size and shape is likely controlled by other factors such as sugars, less complex protein structures in the biofilm matrix or salts in the medium.