Hierarchical Passage of Gold Nanoclusters in Living Bacteria

Gold (Au) nanoclusters chemically synthesized on the cell surface of living Lactobacillus rhamnosus rendered them photoluminescent. Importantly, the bacteria were viable and the clusters were passed down the generations with the loss of luminescence in the first subculture onward. The clusters were agglomerated into spherical structures of 100–200 nm, without being converted to plasmonic Au nanoparticles, on the cell surfaces of the bacteria of all six subcultures studied. The results indicated the role of cell wall remodeling in transforming the Au nanoclusters into larger aggregates down the generations. This may hold important implications for using nanoparticle-studded bacteria in theranostics.