title: Building highly sensitive dye assemblies for biosensing from molecular building blocks.
abstract: Fluorescence superquenching is investigated for polyelectrolytes consisting of cyanine dye pendant polylysines ranging in number of polymer repeat units (N(PRU)) from 1 to 900, both in solution and after adsorption onto silica nanoparticles. As N(PRU) increases, the absorption and fluorescence evolve from monomer spectra to red-shifted features indicative of molecular J aggregates. In solution, the superquenching sensitivity toward an anionic electron acceptor increases by more than a millionfold over the N(PRU) range from 1 to 900. The dramatic increase is attributed to enhanced equilibrium constants for binding the quenchers, and the amplified quenching of a delocalized exciton of approximately 100 polymer repeat units. The self-assembly of monomer onto silica and clay nanoparticles leads to formation of J aggregates, and surface-activated superquenching enhanced 10,000x over the monomer in solution, indicating the formation of "self-assembled polymers" on the nanoparticle surface. Utilization of these self-assembled polymers as high-sensitivity biosensors is demonstrated.
authors.affiliation: QTL Biosystems, LLC, 2778 Agua Fria, Building C, Suite BC, Santa Fe, NM 87507, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Jones
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: R
authors.initials: R
authors.lastname: Helgeson
authors.forename: T S
authors.initials: TS
authors.lastname: Bergstedt
authors.forename: D W
authors.initials: DW
authors.lastname: McBranch
authors.forename: D G
authors.initials: DG
authors.lastname: Whitten
mesh_terms: D015374:Biosensing Techniques; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D008863:Microspheres; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes