title: Self-assembly of supramolecular aptamer structures for optical or electrochemical sensing.
abstract: The self-assembly of labeled aptamer sub-units in the presence of their substrates provides a method for the optical (fluorescence) or electrochemical detection of the substrate. One of the sub-units is linked to CdSe/ZnS quantum dots (QDs), and the self-assembly of the dye-functionalized second sub-unit with the modified QDs, in the presence of cocaine, stimulates fluorescence resonance energy transfer (FRET). This enables the detection of cocaine with a detection limit corresponding to 1 x 10(-6) M. Alternatively, the aptamer fragments are modified with pyrene units. The formation of a supramolecular aptamer-substrate complex allosterically stabilizes the formation of excimer supramolecular structure, and its characteristic emission is observed. In addition, the thiolated aptamer sub-unit is assembled on an Au electrode. The Methylene Blue-labeled sub-unit binds to the surface-confined fragment in the presence of cocaine. The amperometric response of the system allows the detection of cocaine with a detection limit of 1 x 10(-5) M. The approach is generic and can be applied to other substrates, e.g. adenosine triphosphate.
authors.affiliation: Institute of Chemistry, The Center of Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Freeman
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Ran
authors.initials: R
authors.lastname: Tel-Vered
authors.forename: Etery
authors.initials: E
authors.lastname: Sharon
authors.forename: Johann
authors.initials: J
authors.lastname: Elbaz
authors.forename: Itamar
authors.initials: I
authors.lastname: Willner
mesh_terms: D052157:Aptamers, Nucleotide; D015374:Biosensing Techniques; D004563:Electrochemistry; D004566:Electrodes; D045663:Quantum Dots
chemical_list: D052157:Aptamers, Nucleotide