title: Europium-quantum dot nanobioconjugates as luminescent probes for time-gated biosensing.
abstract: Nanobioconjugates have been synthesized using cadmium selenide quantum dots (QDs), europium complexes (EuCs), and biotin. In those conjugates, long-lived photoluminescence (PL) is provided by the europium complexes, which efficiently transfer energy via Förster resonance energy transfer (FRET) to the QDs in close spatial proximity. As a result, the conjugates have a PL emission spectrum characteristic for QDs combined with the long PL decay time characteristic for EuCs. The nanobioconjugates synthesis strategy and photophysical properties are described as well as their performance in a time-resolved streptavidin-biotin PL assay. In order to prepare the QD-EuC-biotin conjugates, first an amphiphilic polymer has been functionalized with the EuC and biotin. Then, the polymer has been brought onto the surface of the QDs (either QD655 or QD705) to provide functionality and to make the QDs water dispersible. Due to a short distance between EuC and QD, an efficient FRET can be observed. Additionally, the QD-EuC-biotin conjugates’ functionality has been demonstratedin a PL assay yielding good signal discrimination, both from autofluorescence and directly excited QDs. These newly designed QD-EuC-biotin conjugates expand the class of highly sensitive tools for bioanalytical optical detection methods for diagnostic and imaging applications.
authors.affiliation: University of Potsdam, Institute of Chemistry, Physical Chemistry, Karl-Liebknecht-Str. 24-25, Potsdam-Golm 14476, GermanybFraunhofer Institute for Applied Polymer Research, NanoPolyPhotonics, Geiselbergstr. 69, Potsdam-Golm 14476, Germany.
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Cywinski
authors.affiliation: University of Potsdam, Institute of Chemistry, Physical Chemistry, Karl-Liebknecht-Str. 24-25, Potsdam-Golm 14476, GermanybFraunhofer Institute for Applied Polymer Research, NanoPolyPhotonics, Geiselbergstr. 69, Potsdam-Golm 14476, Germany.
authors.forename: Tommy
authors.initials: T
authors.lastname: Hammann
authors.affiliation: Philipp University of Marburg, Faculty of Physics, Biophotonics, Renthof 7, Marburg 35037, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Hühn
authors.affiliation: Philipp University of Marburg, Faculty of Physics, Biophotonics, Renthof 7, Marburg 35037, Germany.
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
authors.affiliation: University of Paris-South, Institute for Fundamental Electronics, NanoBioPhotonics, 15 Rue Georges Clémenceau, Orsay 91405, France.
authors.forename: Niko
authors.initials: N
authors.lastname: Hildebrandt
authors.affiliation: University of Potsdam, Institute of Chemistry, Physical Chemistry, Karl-Liebknecht-Str. 24-25, Potsdam-Golm 14476, Germany.
authors.forename: Hans-Gerd
authors.initials: HG
authors.lastname: Löhmannsröben
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000276:immunology*; D005063:Europium / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D007118:Immunoassay / Q000379:methods*; D008163:Luminescent Measurements / Q000379:methods*; D058726:Nanoconjugates; D045663:Quantum Dots; D019809:Streptavidin / Q000276:immunology*
chemical_list: D005456:Fluorescent Dyes; D058726:Nanoconjugates; D005063:Europium; D001710:Biotin; D019809:Streptavidin