Amplified Fluorescence Quenching in a Poly(<i>p</i>-phenylene)-Based Cationic Polyelectrolyte

Harrison, Benjamin S.; Ramey, Michael B.; Reynolds, and John R.; Schanze, Kirk S.

doi:10.1021/ja000819c

Cited by 166 publications

(170 citation statements)

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“…R ecently it has been discovered that certain fluorescent polyelectrolytes-including conjugated polymers and polymers containing pendant cyanine dyes-exhibit very high sensitivity (''superquenching'') to oppositely charged molecular quenchers capable of quenching fluorescence by means of electron or energy transfer (1)(2)(3)(4)(5). Superquenching has been used to develop a rapid, homogeneous, and sensitive format for biosensing and bioassay both in solution and with the polyelectrolyte adsorbed onto supports (1,(6)(7)(8).…”

mentioning

confidence: 99%

Building highly sensitive dye assemblies for biosensing from molecular building blocks

Jones

Lü

Helgeson

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

107

116

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Fluorescence superquenching is investigated for polyelectrolytes consisting of cyanine dye pendant polylysines ranging in number of polymer repeat units (NPRU) from 1 to 900, both in solution and after adsorption onto silica nanoparticles. As NPRU 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 NPRU 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 Ϸ100 polymer repeat units. The self-assembly of monomer onto silica and clay nanoparticles leads to formation of J aggregates, and surface-activated superquenching enhanced 10,000؋ 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. R ecently it has been discovered that certain fluorescent polyelectrolytes-including conjugated polymers and polymers containing pendant cyanine dyes-exhibit very high sensitivity (''superquenching'') to oppositely charged molecular quenchers capable of quenching fluorescence by means of electron or energy transfer (1-5). Superquenching has been used to develop a rapid, homogeneous, and sensitive format for biosensing and bioassay both in solution and with the polyelectrolyte adsorbed onto supports (1, 6-8). We have recently synthesized a series of cyanine pendant poly(L-lysine) derivatives with a number of polymer repeat units (N PRU ) ranging from one to nearly 1,000. As anticipated, the superquenching efficiency in solution increases dramatically (roughly one millionfold) over the range N PRU ϭ 1-900. We find that it is possible to mimic the enhancement in superquenching observed for a polymer in solution by using a monomer or small oligomer self-assembled onto the surface of nanometer-to micrometer-sized supports. This ''surface-activated'' superquenching offers a means of extending the applications of superquenching in biosensing from fluorescent polymers to a range of monomeric and oligomeric dyes. In the present article we report on the remarkable differences in the superquenching observed for the different polymers as a function of the N PRU and the extent of their formation of dye aggregates. We compare the behavior of the individual polymers between solution and supported formats and apply this information to construct a new surface-templated polymeric sensor based on self-assembly of individual oligomeric and monomeric building blocks. Cyanine Dye Pendant Polymer (CDP) Building Blocks in SolutionThe synthesis of the CDP building blocks has been carried out by a two-step synthesis from a starting ''scaffold'' of commercially available poly(L-lysine) as reported elsewhere (9-11, ¶). The approximate N PRU in the starting poly(L-lysine) used in this s...

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mentioning

confidence: 99%

Building highly sensitive dye assemblies for biosensing from molecular building blocks

Jones

Lü

Helgeson

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

107

116

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“…Specifically, the turn-on method works with p-NA peptide derivatives; these derivatives are easily prepared and many are commercially available because they provide the basis for colorimetric assays. In addition, the method can be generalized to p-NA peptides that are negatively charged by using a positively charged CPE (32)(33)(34). The turn-on approach is not limited to p-NA peptides, because a variety of species strongly quench CPE fluorescence, e.g., p-nitrophenyl esters, azobenzene dyes, and diimides.…”

Section: Discussionmentioning

confidence: 99%

Amplified fluorescence sensing of protease activity with conjugated polyelectrolytes

Pinto

Schanze

2004

Proc. Natl. Acad. Sci. U.S.A.

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321

222

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Fluorescent conjugated polyelectrolytes with pendant ionic sulfonate and carboxylate groups are used to sense protease activity. Inclusion of the fluorescent conjugated polyelectrolyte into the assay scheme leads to amplification of the sensory response. The sensing mechanism relies on an electrostatic interaction between the conjugated polyelectrolyte and a peptide substrate that is labeled with a fluorescence quencher. Enzyme activity and hydrolysis kinetics are measured in real time by using fluorescence spectroscopy. Two approaches are presented. In the first approach, a fluorescence turn-on sensor was developed that is based on the use of p-nitroanilide-labeled peptide substrates. In this system enzyme-catalyzed peptide hydrolysis is signaled by an increase in the fluorescence from the conjugated polyelectrolyte. The turn-on system was used to sense peptidase and thrombin activity when the concentrations of the enzyme and substrate are in the nanomolar regime. Kinetic parameters were recovered from real-time assays. In the second approach, a fluorescence turn-off sensor was developed that relies on a peptide-derivatized rhodamine substrate. In the turn-off system enzyme-catalyzed peptide hydrolysis is signaled by a decrease in the fluorescence intensity of the conjugated polyelectrolyte.W ater-soluble, fluorescent -conjugated polyelectrolytes (CPEs) afford a unique platform for the development of highly sensitive fluorescence-based sensors for biological targets (1-4). Signal amplification in CPEs results from a combination of factors, including delocalization and rapid transport of the singlet exciton along the -conjugated backbone, along with the propensity of oppositely charged excited-state quenchers to ion-pair with the ionic groups attached to the CPE chains (1, 5-7). In effect, the CPE acts as a highly effective ''antenna'' that channels excitation energy to a quencher trap site that is ion-paired to the CPE. Chemo-optical signal amplification as high as 1,000-fold has been achieved with CPEs, as assessed by the ability to detect molecular fluorescence quenchers (1, 5).By taking advantage of the intrinsic fluorescence signalamplification properties of CPEs, several groups have recently developed sensitive assays for biologically relevant targets including proteins (1,8,9), DNA (3, 10-12), glycopeptides (13), and carbohydrates (14). Typical CPE-based fluorescence assays allow detection of the target analytes in the nanomolar concentration range (1, 3, 10), and, in a few cases, detection limits in the picomolar range have been reported (11). The CPE-based assays share the common features of being relatively easy to implement and giving a rapid response. Moreover, because the response is detected by using fluorescence, the systems can be adopted to a format that is compatible with f luorescence-based highthroughput screening (HTS) assays (15).In most cases, CPE-based bioassays take advantage of a competition between a nonspecific ion-pairing of an ionic quencher moiety to the CPE chain and the highly sp...

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“…The groups of Wang, 134,135 Fujiki, 136 and Swager 137 have reported the synthesis of fluorescent conjugated polymers able to detect fluoride anions, and the group of Schanze studied the sensing of other anionic quenchers. 138 Sensing of neutral compounds have also been investigated. 139,140 The most successful use of these semiconductor materials as fluorescent probes has been the design of sensors for the detection of vapors of nitroaromatic explosives such as trinitrotoluene (TNT) and dinitrotoluene (DNT).…”

Section: 80mentioning

confidence: 99%

Design of Fluorescent Materials for Chemical Sensing

2007

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There is an enormous demand for chemical sensors for many areas and disciplines. High sensitivity and ease of operation are two main issues for sensor development. Fluorescence techniques can easily fulfill these requirements and therefore fluorescent-based sensors appear as one of the most promising candidates for chemical sensing. However, the development of sensors is not trivial; material science, molecular recognition and device implementation are some of the aspects that play a role in the design of sensors. The development of fluorescent sensing materials is increasingly captivating the attention of the scientists because its implementation as a truly sensory system is straightforward. This critical review shows the use of polymers, sol-gels, mesoporous materials, surfactant aggregates, quantum dots, and glass or gold surfaces, combined with different chemical approaches for the development of fluorescent sensing materials. Representative examples have been selected and they are commented here.

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Amplified Fluorescence Quenching in a Poly(p-phenylene)-Based Cationic Polyelectrolyte

Cited by 166 publications

References 20 publications

Building highly sensitive dye assemblies for biosensing from molecular building blocks

Building highly sensitive dye assemblies for biosensing from molecular building blocks

Amplified fluorescence sensing of protease activity with conjugated polyelectrolytes

Design of Fluorescent Materials for Chemical Sensing

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