title: Enhanced glutathione content allows the in vivo synthesis of fluorescent CdTe nanoparticles by Escherichia coli.
abstract: The vast application of fluorescent semiconductor nanoparticles (NPs) or quantum dots (QDs) has prompted the development of new, cheap and safer methods that allow generating QDs with improved biocompatibility. In this context, green or biological QDs production represents a still unexplored area. This work reports the intracellular CdTe QDs biosynthesis in bacteria. Escherichia coli overexpressing the gshA gene, involved in glutathione (GSH) biosynthesis, was used to produce CdTe QDs. Cells exhibited higher reduced thiols, GSH and Cd/Te contents that allow generating fluorescent intracellular NP-like structures when exposed to CdCl(2) and K(2)TeO(3). Fluorescence microscopy revealed that QDs-producing cells accumulate defined structures of various colors, suggesting the production of differently-sized NPs. Purified fluorescent NPs exhibited structural and spectroscopic properties characteristic of CdTe QDs, as size and absorption/emission spectra. Elemental analysis confirmed that biosynthesized QDs were formed by Cd and Te with Cd/Te ratios expected for CdTe QDs. Finally, fluorescent properties of QDs-producing cells, such as color and intensity, were improved by temperature control and the use of reducing buffers.
authors.affiliation: Microbiology and Bionanotechnology Research Group, Laboratorio de Bioquímica, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Monrás
authors.forename: Víctor
authors.initials: V
authors.lastname: Díaz
authors.forename: Denisse
authors.initials: D
authors.lastname: Bravo
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Montes
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Chasteen
authors.forename: Igor O
authors.initials: IO
authors.lastname: Osorio-Román
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Vásquez
authors.forename: José M
authors.initials: JM
authors.lastname: Pérez-Donoso
mesh_terms: D019187:Cadmium Compounds / Q000378:metabolism*; D002951:Citrates / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics; D005978:Glutathione / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D013691:Tellurium / Q000378:metabolism*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D019187:Cadmium Compounds; D002951:Citrates; D005978:Glutathione; D013691:Tellurium; C028337:cadmium telluride