Abstract:
The spontaneous electron transfer between GaAs
and ionic gold through the galvanic displacement reaction results
in the formation of gold nanoparticles and a Au9Ga4 alloy. We
investigated this process for decorating Legionella pneumophila
and Escherichia coli, aiming at enhanced imaging of these
bacteria. The surface of bacteria was modified with gold ions
through the electrostatic linkage of ionic liquids with phosphate
units of the bacterial cell wall. The modified bacteria were further
incubated with an antibody-functionalized GaAs substrate. Due
to a large gap in the reduction potential of gold and gallium ions,
the induced reaction involving bacteria resulted in a reduction of
the gold ions to gold nanoparticles and oxidation of GaAs to
Ga2O3 and a Au9Ga4 alloy. The bacteria covered with a Au/
AuGa nanoshell, if excited at 377 nm, show a bright emission at
447 nm originating from Au/Au9Ga4. This approach offers a simple and potentially less expensive method for high-contrast
imaging of bacteria in comparison to the conventional methods of staining with different dyes or by conjugating green
fluorescent proteins.
