title: Reversible modulation of quantum dot photoluminescence using a protein- bound photochromic fluorescence resonance energy transfer acceptor.
abstract: Multiple copies ( approximately 20) of Escherichia coli maltose binding protein (MBP) were coordinated to luminescent semiconductor quantum dots (QDs) via a C-terminal oligohistidine segment. The MBP was labeled with a sulfo-N-hydroxysuccinimide-activated photochromic BIPS molecule (1',3-dihydro-1'-(2-carboxyethyl)-3,3-dimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-(2H)-indoline]) at two different dye-to-MBP ratios; D/P = 1 and 5. The ability of MBP-BIPS to modulate QD photoluminescence was tested by switching BIPS from the colorless spiropyran (SP) to the colored merocyanine (MC) using white light (>500 nm) or UV light ( approximately 365 nm), respectively. QDs surrounded by MBP-BIPS with D/P = 1 were quenched on average approximately 25% with consecutive repeated switches, while QDs surrounded by MBP-BIPS with D/P = 5 were quenched approximately 60%. This result suggests a possible use of BIPS-labeled proteins in QD-based nanostructures as part of a threshold switch or other biosensing device.
authors.affiliation: Center for Bio/Molecular Science and Engineering, Code 6900, Division of Optical Sciences, Code 5611, U.S. Naval Research Laboratory, Washington, DC 20375, USA. imedintz@cbmse.nrl.navy.mil
authors.forename: Igor L
authors.initials: IL
authors.lastname: Medintz
authors.forename: Scott A
authors.initials: SA
authors.lastname: Trammell
authors.forename: Hedi
authors.initials: H
authors.lastname: Mattoussi
authors.forename: J Matthew
authors.initials: JM
authors.lastname: Mauro
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D007211:Indoles / Q000737:chemistry*; D008163:Luminescent Measurements; D058619:Maltose-Binding Proteins; D036103:Nanotechnology; D045663:Quantum Dots
chemical_list: C483331:1',3-dihydro-1'-(2-carboxyethyl)-3,3-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2'-(2H)-indoline); D001578:Benzopyrans; D002352:Carrier Proteins; D007211:Indoles; D058619:Maltose-Binding Proteins