title: Self-assembled nanoscale biosensors based on quantum dot FRET donors.
abstract: The potential of luminescent semiconductor quantum dots (QDs) to enable development of hybrid inorganic-bioreceptor sensing materials has remained largely unrealized. We report the design, formation and testing of QD-protein assemblies that function as chemical sensors. In these assemblies, multiple copies of Escherichia coli maltose-binding protein (MBP) coordinate to each QD by a C-terminal oligohistidine segment and function as sugar receptors. Sensors are self-assembled in solution in a controllable manner. In one configuration, a beta-cyclodextrin-QSY9 dark quencher conjugate bound in the MBP saccharide binding site results in fluorescence resonance energy-transfer (FRET) quenching of QD photoluminescence. Added maltose displaces the beta-cyclodextrin-QSY9, and QD photoluminescence increases in a systematic manner. A second maltose sensor assembly consists of QDs coupled with Cy3-labelled MBP bound to beta-cyclodextrin-Cy3.5. In this case, the QD donor drives sensor function through a two-step FRET mechanism that overcomes inherent QD donor-acceptor distance limitations. Quantum dot-biomolecule assemblies constructed using these methods may facilitate development of new hybrid sensing materials.
authors.affiliation: Center for Bio/Molecular Science and Engineering, Code 6910, US Naval Research Laboratory, Washington, DC 20375, USA.
authors.forename: Igor L
authors.initials: IL
authors.lastname: Medintz
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Clapp
authors.forename: Hedi
authors.initials: H
authors.lastname: Mattoussi
authors.forename: Ellen R
authors.initials: ER
authors.lastname: Goldman
authors.forename: Brent
authors.initials: B
authors.lastname: Fisher
authors.forename: J Matthew
authors.initials: JM
authors.lastname: Mauro
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D029968:Escherichia coli Proteins / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer / Q000295:instrumentation* / Q000379:methods; D008320:Maltose / Q000032:analysis* / Q000737:chemistry; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D033902:Periplasmic Binding Proteins / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D033902:Periplasmic Binding Proteins; D008320:Maltose