Microbial Synthesis of Semiconductor PbS Nanocrystallites

The use of microbes as producers of semiconductor nanocrystals is demonstrated. When torulopsis yeast is challenged with lead, it builds intracellular spherical crystallites of PbS, 2–5 nm in diameter (see Figure for an HR-TEM image) and pure by X-ray diffraction. The crystals, which can be isolated by freeze-thawing, show a sharp absorption maximum at 330 nm, corresponding to a bandgap of 3.75 eV.