Abstract
Stable colloidal nanoparticles (NPs) such as Au and Ag NPs have been studied for use in enhancing the secondary ion signals from SIMS analysis. Semiconducting zinc oxide (ZnO) NPs possess unique properties of chemical and thermal stability as well as a wide bandgap energy of 3.37 eV, which motivated us to study the feasibility of using ZnO NPs to enhance the secondary ion signals using Escherichia coli (E. coli) as model sample. The experiment was carried out first by depositing ZnO NPs onto freeze-dried E. coli colony by dropping ZnO NPs solution onto colony top. The prepared E. coli wes then subjected to time-of-flight SIMS (ToF-SIMS) analysis operating with Ga + bombardment. We evaluated the signal enhancement using ion signals of m/z 688 (PE C32:1) and m/z 719 (PG C32:1) from the lipid membrane Preliminary results indicate an enhancement factor of ∼3 by depositing ZnO NPs onto E. coli. Copyright © 2010 John Wiley & Sons, Ltd.