Fluorometric detection of sulfate-reducing bacteria via the aggregation-induced emission of glutathione-gold(I) complexes

It is reported that gold(I)-thiolate complexes can display aggregation-induced emission (AIE) similar to organic fluorogens. On addition of lead(II) to glutathione-gold(I) complexes, a supermolecular structure of type GSH-Au(I)-Pb(II) is formed through strong coordination between Pb(II) and GSH. Its fluorescence is quenched by sulfide due to the formation of PbS which destroys the GSH-Au(I)-Pb(II) complex. The finding was used to design a method for fluorometric detection of sulfate-reducing bacteria (SRB) which produce sulfide. The time needed to reduce fluorescence to 10% of its initial intensity linearly dependent on the logarithm of the SRB concentrations in the ranging from 10 to 1 × 10^7 cfu mL−1. The assay time is also reduced down to 4 days even if the SRB concentration is as low as 10 cfu mL−1.