title: Imaging Escherichia coli using functionalized core/shell CdSe/CdS quantum dots.
abstract: The internalization of a series of water-soluble CdSe/CdS quantum dots (QDs) stabilized by citrate, isocitrate, succinate, and malate by Escherichia coli is established by epifluorescence and confocal fluorescence scanning microscopy, fluorimetry, and UV-vis spectroscopy on whole and lysed bacterial cells. The organic-acid-stabilized QDs span a range in size from 3.8+/-1.1 to 6.0+/-2.4 nm with emission wavelengths from 540 to 630 nm. QDs of different sizes (i.e., 3.8-6 nm) can enter the bacterium and be detected on different fluorescence channels with little interference from other QDs as a result of the distinct emission profiles (i.e., 540-630 nm, respectively). Costaining QD-labeled E. coli with 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) demonstrates that the QDs and DAPI are colocalized within E. coli, whereas costaining QD-labeled E. coli with membrane dye FM4-64 shows that the FM4-64 is localized in the outer bacterial membrane and that the QDs are inside.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Hirschey
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Han
authors.forename: Galen D
authors.initials: GD
authors.lastname: Stucky
authors.forename: Alison
authors.initials: A
authors.lastname: Butler
mesh_terms: D019187:Cadmium Compounds / Q000378:metabolism*; D004926:Escherichia coli / Q000166:cytology* / Q000378:metabolism; D018613:Microscopy, Confocal; D045663:Quantum Dots; D018036:Selenium Compounds / Q000378:metabolism*; D013194:Staining and Labeling / Q000379:methods*; D013440:Sulfides / Q000378:metabolism*
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C058667:cadmium selenide