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Transformations of Biologically-Conjugated CdSe Quantum Dots Released into Water and Biofilms

Donald Bren School of Environmental Science & Management. Transformations of Biologically-Conjugated CdSe Quantum Dots Released into Water and Biofilms. P.A. Holden J.L. Nadeau UC Santa Barbara McGill University. Quantum Dots. 3 to 7 nm (bare CdSe)

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Transformations of Biologically-Conjugated CdSe Quantum Dots Released into Water and Biofilms

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  1. Donald Bren School of Environmental Science & Management Transformations of Biologically-Conjugated CdSe Quantum Dots Released into Water and Biofilms P.A. Holden J.L. Nadeau UC Santa Barbara McGill University

  2. Quantum Dots • 3 to 7 nm (bare CdSe) • used in biological labeling • wide absorbance, narrow emission spectra absorbance emission triple-labeled S. aureus

  3. Quantum Dots (cont.) bare core shell conjugated

  4. Project Goals • Determine fates of CdSe QDs under abiotic and biotic conditions • Determine toxicity of QDs to bacteria • Determine damage of QDs to DNA • Determine how QD coating or conjugation alters effects • Compare effects of dissolved Cd and Se

  5. Research Objectives (1/2) • Quantify QD breakdown in aqueous solutions • pH, reducing conditions, light, oxygen • bare, core-shell, conjugated QDs • Quantify microbial uptake and breakdown • liquid culture, S. aureus, P. aeruginosa • growth effects, QD fates, breakdown products

  6. Research Objectives (2/2) • Investigate DNA damage • oxidation of isolated G and A by TCSPC • oxidation of G in DNA; quantify oxidation product • Investigate effects on and of bacterial biofilms • saturated and unsaturated • growth effects, toxicity, & macromolecular interactions • breakthrough in colonized porous media

  7. Preliminary Data • acid quenches more than base (A) • reduction-mediated partial quenching (B) • light-mediated fluorescence enhancement (C)

  8. Preliminary Data (cont.) B. subtilis aprt mutants label brightly with CdSe-AMP QDs (light, pH 5) QDs effectively stain cells for TEM imaging

  9. Preliminary Data (cont.) • adenine quenches green (left) and red (right) QDs • light restores

  10. Project Plans • 3 years, begin late 2004 • Initially establish protocols across labs • Nadeau Lab • Aqueous fates • Liquid culture effects and fates • DNA oxidative damage • Holden Lab • Biofilm studies • Column breakthrough characteristics

  11. Acknowledgements This project is to be funded by the USEPA. B. Lea Cox assisted with the proposal.

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