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Comment
. 2001 Dec 18;98(26):14769-72.
doi: 10.1073/pnas.251555298. Epub 2001 Dec 11.

Building highly sensitive dye assemblies for biosensing from molecular building blocks

R M Jones  1 , L Lu, R Helgeson, T S Bergstedt, D W McBranch, D G Whitten
Affiliations
Comment

Building highly sensitive dye assemblies for biosensing from molecular building blocks

R M Jones et al. Proc Natl Acad Sci U S A. .

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.

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Figures

Scheme 1
Scheme 1
Figure 1
Figure 1
Normalized absorption and emission spectra of CDP as a function of NPRU.
Figure 2
Figure 2
Fluorescence quenching of CDP as a function of NPRU. Left axis, Ksv; right axis, PRU/Q50. Solid blue line (▴) is for silica-supported CDP, dashed red line (□) is for solution phase polymers. In the main figure, the data are plotted for clarity on a log–log scale. (Inset) The same data on a linear scale.
Figure 3
Figure 3
Q/P50 for CDP as a function of NPRU. Solid blue line (▴) is for silica-supported CDP, dashed red line (□) is for solution-phase polymers.
Figure 4
Figure 4
Absorption spectra showing adsorption of 1 (17.2 μM/1.2% methanol in water) onto Laponite clay nanoparticles: black curve is starting mixture of monomeric 1 and J aggregate microcrystals. Successive curves (follow arrows) show spectral changes occurring on successive addition of microgram portions of Laponite nanoparticles. (Inset) Quench–unquench experiments of Laponite-supported 1 J aggregate in water. Black curve is starting emission from nanoparticles in water; red curve is emission quenched by the addition of 100 nM V-B+; blue and green curves show recovery on successive additions of 25 nM avidin.
Scheme 2
Scheme 2
See this image and copyright information in PMC

Comment on

References

    1. Chen L, McBranch D W, Wang H-L, Helgeson R, Wudl F, Whitten D G. Proc Natl Acad Sci USA. 1999;96:12287–12292. - PMC - PubMed
    1. Chen L, McBranch D, Wang R, Whitten D. Chem Phys Lett. 2000;330:27–33.
    1. Chen L, Xu S, McBranch D, Whitten D. J Am Chem Soc. 2000;122:9302–9303.
    1. Wang J, Wang D, Miller E K, Moses D, Bazan G C, Heeger A J. Macromolecules. 2000;33:5153–5158.
    1. Harrison B S, Ramey M B, Reynolds J R, Schanze K S. J Am Chem Soc. 2000;122:8561–8562.

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