title: Aptamer-capped nanocrystal quantum dots: a new method for label-free protein detection.
abstract: We demonstrate that aptamer-capped near-infrared PbS quantum dots (QDs) can detect a target protein based on selective charge transfer. The water-soluble QDs are synthesized with the thrombin-binding aptamer, which retains the secondary quadruplex structure necessary for binding to thrombin. These QDs have diameters of 3-6 nm and fluoresce around 1050 nm. When the aptamer-functionalized QD binds to its target, a fluorescence quenching occurs due to charge transfer from amine groups on the protein to the QD. Thrombin is detected within 1 min with a detection limit of approximately 1 nM. This selective detection is observed even in the presence of high background concentrations of interfering negatively or positively charged proteins, suggesting that aptamer-capped QDs could be useful for label-free protein assays.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Choi
authors.forename: Kok Hao
authors.initials: KH
authors.lastname: Chen
authors.forename: Michael S
authors.initials: MS
authors.lastname: Strano
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D019286:Endopeptidase K / Q000032:analysis; D007700:Kinetics; D009113:Muramidase / Q000032:analysis; D053758:Nanoparticles; D011506:Proteins / Q000032:analysis*; D045663:Quantum Dots; D012710:Serum Albumin, Bovine / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D011506:Proteins; D012710:Serum Albumin, Bovine; D009113:Muramidase; D019286:Endopeptidase K