title: Biological synthesis of fluorescent nanoparticles by cadmium and tellurite resistant Antarctic bacteria: exploring novel natural nanofactories.
abstract: BACKGROUND
  Fluorescent nanoparticles or quantum dots (QDs) have been intensely studied for basic and applied research due to their unique size-dependent properties. There is an increasing interest in developing ecofriendly methods to synthesize these nanoparticles since they improve biocompatibility and avoid the generation of toxic byproducts. The use of biological systems, particularly prokaryotes, has emerged as a promising alternative. Recent studies indicate that QDs biosynthesis is related to factors such as cellular redox status and antioxidant defenses. Based on this, the mixture of extreme conditions of Antarctica would allow the development of natural QDs producing bacteria.
  
  
  RESULTS
  In this study we isolated and characterized cadmium and tellurite resistant Antarctic bacteria capable of synthesizing CdS and CdTe QDs when exposed to these oxidizing heavy metals. A time dependent change in fluorescence emission color, moving from green to red, was determined on bacterial cells exposed to metals. Biosynthesis was observed in cells grown at different temperatures and high metal concentrations. Electron microscopy analysis of treated cells revealed nanometric electron-dense elements and structures resembling membrane vesicles mostly associated to periplasmic space. Purified biosynthesized QDs displayed broad absorption and emission spectra characteristic of biogenic Cd nanoparticles.
  
  
  CONCLUSIONS
  Our work presents a novel and simple biological approach to produce QDs at room temperature by using heavy metal resistant Antarctic bacteria, highlighting the unique properties of these microorganisms as potent natural producers of nano-scale materials and promising candidates for bioremediation purposes.
authors.affiliation: BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Facultad de Ciencias Biológicas, Universidad Andres Bello, República # 239, Santiago, Chile.|Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Sergio Livingstone Pohlhammer # 1007, Santiago, Chile.
authors.forename: D O
authors.initials: DO
authors.lastname: Plaza
authors.affiliation: BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Facultad de Ciencias Biológicas, Universidad Andres Bello, República # 239, Santiago, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Gallardo
authors.affiliation: BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Facultad de Ciencias Biológicas, Universidad Andres Bello, República # 239, Santiago, Chile.
authors.forename: Y D
authors.initials: YD
authors.lastname: Straub
authors.affiliation: Laboratorio de Microbiología Oral, Facultad de Odontología, Universidad de Chile, Sergio Livingstone Pohlhammer # 943, Santiago, Chile.
authors.forename: D
authors.initials: D
authors.lastname: Bravo
authors.affiliation: BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Facultad de Ciencias Biológicas, Universidad Andres Bello, República # 239, Santiago, Chile. jose.perez@unab.cl.
authors.forename: J M
authors.initials: JM
authors.lastname: Pérez-Donoso
mesh_terms: D000864:Antarctic Regions; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D019187:Cadmium Compounds / Q000737:chemistry*; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D005456:Fluorescent Dyes / Q000737:chemistry*; D055442:Metabolome; D019216:Metals, Heavy / Q000633:toxicity; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D045663:Quantum Dots / Q000737:chemistry / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013440:Sulfides / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D005456:Fluorescent Dyes; D019216:Metals, Heavy; D012336:RNA, Ribosomal, 16S; D013440:Sulfides; C034939:cadmium sulfide; D013691:Tellurium; C028337:cadmium telluride
keywords: Antarctica; Bacteria; Fluorescent nanoparticles; Green synthesis; Heavy metals; Quantum dots