title: Terbium to quantum dot FRET bioconjugates for clinical diagnostics: influence of human plasma on optical and assembly properties.
abstract: Förster resonance energy transfer (FRET) from luminescent terbium complexes (LTC) as donors to semiconductor quantum dots (QDs) as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma.
authors.affiliation: NanoPolyPhotonik, Fraunhofer Institut für Angewandte Polymerforschung, D-14476 Potsdam, Germany. frank.morgner@iap.fraunhofer.de
authors.forename: Frank
authors.initials: F
authors.lastname: Morgner
authors.forename: Stefan
authors.initials: S
authors.lastname: Stufler
authors.forename: Daniel
authors.initials: D
authors.lastname: Geissler
authors.forename: Igor L
authors.initials: IL
authors.lastname: Medintz
authors.forename: W Russ
authors.initials: WR
authors.lastname: Algar
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Susumu
authors.forename: Michael H
authors.initials: MH
authors.lastname: Stewart
authors.forename: Juan B
authors.initials: JB
authors.lastname: Blanco-Canosa
authors.forename: Philip E
authors.initials: PE
authors.lastname: Dawson
authors.forename: Niko
authors.initials: N
authors.lastname: Hildebrandt
mesh_terms: D000042:Absorption; D000818:Animals; D001710:Biotin / Q000378:metabolism; D002021:Buffers; D002417:Cattle; D019937:Diagnostic Techniques and Procedures; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006639:Histidine / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D057230:Limit of Detection; D055620:Optical Phenomena; D010949:Plasma / Q000737:chemistry*; D011485:Protein Binding; D045663:Quantum Dots; D012710:Serum Albumin, Bovine / Q000378:metabolism; D019809:Streptavidin / Q000378:metabolism; D013725:Terbium / Q000737:chemistry*; D015032:Zinc / Q000378:metabolism
chemical_list: D002021:Buffers; D013725:Terbium; C033223:polyhistidine; D012710:Serum Albumin, Bovine; D006639:Histidine; D001710:Biotin; D019809:Streptavidin; D015032:Zinc