title: Thermal and photo stability of glutathione-capped cadmium telluride quantum dots.
abstract: BACKGROUND
  Nanoparticles (NPs) are increasingly being used in a number of applications that include biomedicine, biological labeling and cancer marker targeting, and their successful storage is important to preserve their viability. A systematic investigation of the thermal and photo stability of chemically stabilized cadmium telluride (CdTe) quantum dots (QDs) under various storage conditions either in solution or as dried nanoparticles has not been published. Here we report experiments involving chemically synthesized glutathione-capped CdTe QDs whose photoluminescence spectra were examined initially and then periodically during storage times up to 76 days.
  
  
  METHODS
  Samples of dried QDs or QDs in solution (water or buffered) were examined under different light conditions including complete darkness, constant 12,000 lux incident light, and under diurnal sunlight; at temperatures ranging from -80 °C to room temperature.
  
  
  RESULTS
  Though QDs stored in solution in the dark at -80 °C lost only 50% of peak fluorescence (FL510) within 2 weeks, solution-stored QDs exposed to sunlight at room temperature showed FL510 drops of 85% in the first 24 hours. In contrast, QDs precipitated from aqueous solution, dried and stored in time course experiments in the presence of atmospheric oxygen--when resuspended in water--lost an average of only 12% FL510 over 76 days under all conditions tested, even in direct sunlight.
  
  
  CONCLUSIONS
  Glutathione-capped CdTe particles can be stored as dried nanoparticles for extended periods of time, enhancing their viability in biomedicine, biological labeling and cancer marker targeting.
authors.affiliation: Department of Chemistry and Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, Texas - USA.
authors.forename: Poorna T
authors.initials: PT
authors.lastname: Wansapura
authors.affiliation: Faculty of Chemistry and Biology, University of Santiago, Santiago - Chile.|Faculty of Health Sciences, San Sebastián University, Santiago - Chile.
authors.forename: Waldo A
authors.initials: WA
authors.lastname: Díaz-Vásquez
authors.affiliation: Faculty of Chemistry and Biology, University of Santiago, Santiago - Chile.
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Vásquez
authors.affiliation: Bionanotechnology and Microbiology Lab, Center for Bioinformatics and Integrative Biology (CBIB), Andrés Bello University, Santiago - Chile.
authors.forename: José M
authors.initials: JM
authors.lastname: Pérez-Donoso
authors.affiliation: Department of Chemistry and Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, Texas - USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Chasteen
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D004355:Drug Stability; D005978:Glutathione / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D045663:Quantum Dots / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013691:Tellurium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D013438:Sulfhydryl Compounds; D005978:Glutathione; D013691:Tellurium; C028337:cadmium telluride