Near-Infrared Fluorescence Probes

Casay, Guillermo A.; Shealy, Dana B.; Patonay, Gábor

doi:10.1007/0-306-47060-8_7

Cited by 17 publications

(18 citation statements)

References 92 publications

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“…Also, it seems possible that nanoparticles could display resonance energy transfer, as has been suggested in some early reports. [42][43] Energy transfer between nanoparticles has been detected. [52][53] Methyl viologen was reported to quench ZnS particle emission, but it is not known if the mechanism involved Förster transfer.…”

Section: Discussionmentioning

confidence: 99%

Luminescence Spectral Properties of CdS Nanoparticles

et al. 1999

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We examined the steady state and time resolved luminescence spectral properties of two types of CdS nanoparticles. CdS nanoparticles formed in the presence of an amine-terminated dendrimer showed blue emission. The emission wavelength of these nanoparticles depended on the excitation wavelength. The CdS/dendrimer nanoparticles displayed polarized emission with the anisotropy rising progressively from 340 to 420 nm excitation, reaching a maximal value in excess of 0.3. To the best of our knowledge this is the first report of a constant positive polarized emission from luminescent nanoparticles. We also examined a second type of nanoparticle, polyphosphatestabilized CdS. These polyphosphate-stabilized nanoparticles displayed a longer wavelength red emission maximum and displayed a zero anisotropy for all excitation wavelengths. Both nanoparticles displayed strongly heterogeneous intensity decays with mean decay times of 93 ns and 10 μs for the blue and red emitting particles, respectively. Both types of nanoparticles were found to be severalfold more photostable upon continuous illumination than fluorescein. Despite the long decay times, the nanoparticles are mostly insensitive to dissolved oxygen but were quenched by iodide. These results suggest that nanoparticles can provide a new class of luminophores for use in chemical sensing, DNA sequencing, high throughput screening and other biotechnology applications.

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Section: Discussionmentioning

confidence: 99%

Luminescence Spectral Properties of CdS Nanoparticles

et al. 1999

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“…Hence the electric field is described by 5For TIR we need to consider the electric field along the x axis, the prism-water interface. This component is given by (6) To satisfy Maxwell's equations the electric fields have to be continuous across the interface, which requires k x to be equal in both media. Hence 7Since k P = n P ω/c and k 0 = n 0 ω/c continuity across the interface requires the angles to be related according to Eq.…”

Section: Theory Of Surface Plasmon Resonancementioning

confidence: 99%

“…Numerous methods to increase sensitivity have been developed. These methods include amplified assays such as enzyme-linked immunosorbent assay [1] and PCR [2], probes with multiple fluorophores such as the phycobiliproteins [3,4], long-wavelength probes [5,6], and/ or gated detection to decrease the background emission [7,8]. Several fundamental factors limit the sensitivity of fluorescence methods, typically photodestruction of the fluorophores and the extent of background fluorescence.…”

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confidence: 99%

Radiative decay engineering 3. Surface plasmon-coupled directional emission

Lakowicz

2004

Analytical Biochemistry

438

586

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A new method of fluorescence detection that promises to increase sensitivity by 20- to 1000-fold is described. This method will also decrease the contribution of sample autofluorescence to the detected signal. The method depends on the coupling of excited fluorophores with the surface plasmon resonance present in thin metal films, typically silver and gold. The phenomenon of surface plasmon-coupled emission (SPCE) occurs for fluorophores 20-250 nm from the metal surface, allowing detection of fluorophores over substantial distances beyond the metal-sample interface. SPCE depends on interactions of the excited fluorophore with the metal surface. This interaction is independent of the mode of excitation; that is, it does not require evanescent wave or surface-plasmon excitation. In a sense, SPCE is the inverse process of the surface plasmon resonance absorption of thin metal films. Importantly, SPCE occurs over a narrow angular distribution, converting normally isotropic emission into easily collected directional emission. Up to 50% of the emission from unoriented samples can be collected, much larger than typical fluorescence collection efficiencies near 1% or less. SPCE is due only to fluorophores near the metal surface and may be regarded as emission from the induced surface plasmons. Autofluorescence from more distal parts of the sample is decreased due to decreased coupling. SPCE is highly polarized and autofluorescence can be further decreased by collecting only the polarized component or only the light propagating with the appropriate angle. Examples showing how simple optical configurations can be used in diagnostics, sensing, or biotechnology applications are presented. Surface plasmon-coupled emission is likely to find widespread applications throughout the biosciences.

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“…While fluorescence is a highly sensitive method, there is always a need for increased sensitivity to detect smaller and smaller numbers of target molecules. Numerous approaches are used to obtain increased detectability, including amplified assays such as ELISA [1] and PCR [2], probe with multiple fluorophores such as the phycobiliproteins [3,4], long wavelength excitation [5,6], and/or gated detection to decrease the background emission [7,8]. Several fundamental factors limit the sensitivity of fluorescence methods, typically photodestruction of the fluorophores and the extent of background fluorescence.…”

mentioning

confidence: 99%

Directional surface plasmon-coupled emission: a new method for high sensitivity detection

Lakowicz

Malicka

Gryczyński

et al. 2003

Biochemical and Biophysical Research Communications

143

108

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Fluorescence emission is nearly isotropic in space. With typical optical components the collection efficiency is 1% or less. In this preliminary report, we describe a novel approach to transforming the normally isotropic emission into directional emission with a collection efficiency near 50%. This can be accomplished for fluorophores located near a semi-transparent silver film on a glass substrate. The emission couples with the surface plasmon resonance on the silver surface and enters the transparent substrate at a sharply defined angle, the surface plasmon angle for the emission wavelength. We estimate that 40-70% of the total emission enters the substrate at the plasmon angle and can thus be directed towards a detector. Background emission from fluorophores distant from the silver does not couple with the plasmon and is not detected. Different emission wavelengths couple at different angles allowing spectral discrimination without additional optics. Surface plasmon-coupled emission represents a new technology which can be used for high detection efficiency with microfluidic and/or surface-bound assay formats.

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Near-Infrared Fluorescence Probes

Cited by 17 publications

References 92 publications

Luminescence Spectral Properties of CdS Nanoparticles

Luminescence Spectral Properties of CdS Nanoparticles

Radiative decay engineering 3. Surface plasmon-coupled directional emission

Directional surface plasmon-coupled emission: a new method for high sensitivity detection

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