title: Quantum dot-antibody and aptamer conjugates shift fluorescence upon binding bacteria.
abstract: CdSe/ZnS quantum dots (QDs) exhibited fluorescence emission blue shifts when conjugated to antibodies or DNA aptamers that are bound to bacteria. The intensity of the shifted emission peak increased with the number of bound bacteria. Curiously, the emission was consistently shifted to approximately 440-460 nm, which is distinctly different from the major component of the natural fluorescence spectrum of these QDs. This minor emission peak can grow upon conjugation to antibodies or aptamers and subsequent binding to bacterial cell surfaces. We hypothesize that the wavelength shift is due to changes in the chemical environment of the QD conjugates when they encounter the bacterial surface and may be due to physical deformation of the QD that changes the quantum confinement state. Regardless of the mechanism, these remarkable emission wavelength shifts of greater than 140 nm in some cases strongly suggest new applications for QD-receptor conjugates.
authors.affiliation: NanoScience Diagnostics, Inc., 10520 Canyon Vista Way, Austin, TX 78726, USA. su@nanosciencediagnostics.com
authors.forename: Sulatha
authors.initials: S
authors.lastname: Dwarakanath
authors.forename: John G
authors.initials: JG
authors.lastname: Bruno
authors.forename: Anant
authors.initials: A
authors.lastname: Shastry
authors.forename: Taylor
authors.initials: T
authors.lastname: Phillips
authors.forename: Ashley A
authors.initials: AA
authors.lastname: John
authors.forename: Ashely
authors.initials: A
authors.lastname: John
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
authors.forename: Larry D
authors.initials: LD
authors.lastname: Stephenson
mesh_terms: D000936:Antigen-Antibody Complex / Q000032:analysis*; D001681:Biological Assay / Q000379:methods*; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification*; D005434:Flow Cytometry / Q000379:methods*; D008024:Ligands; D008856:Microscopy, Fluorescence / Q000379:methods*; D011485:Protein Binding; D045663:Quantum Dots
chemical_list: D000936:Antigen-Antibody Complex; D008024:Ligands