Self-assembled nanoscale biosensors based on quantum dot FRET donors.
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.
Medintz
Igor L
IL
Center for Bio/Molecular Science and Engineering, Code 6910, US Naval Research Laboratory, Washington, DC 20375, USA.
Clapp
Aaron R
AR
Mattoussi
Hedi
H
Goldman
Ellen R
ER
Fisher
Brent
B
Mauro
J Matthew
JM
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
D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D033902:Periplasmic Binding Proteins; D008320:Maltose