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Imaging the Hydrated Microbe‐Metal Interface Using Nanoscale Spectrum Imaging
Author(s) -
Lewis Edward A.,
Downie Helen,
Collins Richard F.,
Prestat Eric,
Lloyd Jonathan R.,
Haigh Sarah J.
Publication year - 2016
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.201600073
Subject(s) - bimetallic strip , nanotechnology , geobacter sulfurreducens , materials science , scanning transmission electron microscopy , nanocrystal , nanoscopic scale , transmission electron microscopy , nanoparticle , nanostructure , metal , biofilm , bacteria , metallurgy , biology , genetics
PdAu nanocrystals are synthesised by Geobacter sulfurreducens , a dissimilatory metal‐reducing bacterium, and the resulting bimetallic nanocrystal‐decorated microbes are imaged using a range of advanced electron microscopy techniques. Specifically, the first example of elemental mapping of fully hydrated biological nanostructures using scanning transmission electron microscope (STEM) energy dispersive X‐ray (EDX) spectrum imaging within an environmental liquid‐cell is reported. These results are combined with cryo‐TEM and ex situ STEM imaging and EDX analysis with the aim of better understanding microbial synthesis of bimetallic nanoparticles. It is demonstrated that although Au and Pd are colocalized across the cells, the population of nanoparticles produced is bimodal, containing ultrasmall alloyed nanocrystals with diameters <3 nm and significantly larger core‐shell structures (>200 nm in diameter) which show higher Pd contents and exhibit a Pd enriched shell only a few nanometers thick. The application of high‐resolution imaging techniques described here offers the potential to visualize the microbe‐metal interface during the bioproduction of a range of functional materials by microbial “green” synthesis routes, and also key interfaces underpinning globally relevant environmental processes (e.g., metal cycling).