Fluorescent tracer

Spatial information about a system can be obtained by analyzing the spatial distribution of PL intensity. Fluorescent tracers may be used to image chemical uptake in biological systems. Luminescence profiles have proven useftil in the semiconductor industry for mapping impurity distributions, dislocadons, or structural homogeneity in substrate wafers or epilayers. Similar spatial infbrmadon over small regions is obtained by cathodoluminescence imaging. 

If a serious leak is suspected, use a fluorescent tracer dye to identify the source of the leak. These dyes can be seen in drains and other dark places with the aid of an ultraviolet lamp at concentrations of below 1 ppm. 

PIV has become the most popular technique to measure velocity and turbulent properties (Figure 15.1). The movement of seed particles in a millimeter-thick laser sheet is measured by correlating two photos taken a few milliseconds apart. With two cameras, it is also possible to obtain a 3D vector of the velocity in that plane. The method gives, in general, very good resolution of the flow, but it requires optical access. Also, measurement close to walls can be problematic due to light reflections that disturb the measurements. One extension of PIV is the micro-PIV that uses fluorescent tracer particles, which allows all direct light, for example, reflections at the walls, to be filtered out [1]. 

Fenske, R.A. (1988) Correlation of fluorescent tracer measurements of dermal exposure and urinary metabolite excretion during occupational exposure to malathion, Am. Ind. Hygiene Assoc. /., 49 438-444. 

C) and (D) highlight a cholinergic LDT/PPT neuron (C) that was identified via retrograde fluorescent tracer (D) as projecting to the medial pontine reticular formation. (Modified from Lydic Baghdoyan, 2005). (See also Plate 4.)... 

The formation of complexes of the fluorescent tracer dye ammonium 1-phenyl-aminonaphthalene-8-sulphonate (10.41) with cyclodextrins has been investigated with favourable results, especially in environmental studies [33]. The ability of this dye to complex with cyclodextrins has been exploited mainly as an analytical tool in the study of cyclodextrin applications, since its fluorescence is easily measured. The interaction of a-, P-and y-cyclodextrins with azo acid dyes containing alkyl chains of different lengths has been reported [36,37]. The formation and isolation of solid complexes between P-cyclodextrin and Cl Acid Red 42, Cl Acid Blue 40 or Erionyl Bordeaux 5BLF (Ciba) have been reported [29]. 

Fluorescence lifetime-based applications require probes and labels with environment-sensitive lifetimes, while immunoassays or hybridization-based analysis require fluorescent tracers preferably labeled with a single, mono-reactive fluorescent label. 

Due to their displayed higher photostability, indolenine-based cyanines and squaraines are preferred for the design of fluorescent tracers. Dicyanomethylene- and thio-squaraines with substituted squaraine oxygens also show potential as highly photostable fluorescent probes. 

The immobilisation of proteins into inorganic mesoporous host materials has attracted considerable attention due to the potential applications in biochemical, biomedical, industrial and bio-analytical fields [1] Biocompatible supports endowed with fluorescent tracers and adequately modified for specific interactions with cellular antigens are an amenable tool for image in living cells processes that are relevant to diseases. 

Goodwin PB, Shepherd V, Erwee MG. Compartmentation of fluorescent tracers injected into the epidermal cells of Egeriadensalsmss. Planta 1990 181 129-136. 

A fiber optic immunosensor (FOI) has also been reported for detection of PCBs in Aroclors [204]. The quartz fiber surface is coated with PAbs against PCBs and the competitive assay takes place using as fluorescent tracer, an analog of the analyte coupled to 2,4,5-trichlorophenoxybutyrate (TCPB) on the Ab-coated fiber. The LOD achieved is around 10 pg L L... 

Using the same PAbs an optical biosensor system has been developed for 2,4,6-TCP [224]. The principle is the detection of laser-induced fluorescence (LIF) in single microdroplets by a homogeneous quenching fluorescence immunoassay (QFIA). The competitive immunoassay occurs in microdroplets (d=58.4 mm) produced by a piezoelectric generator system. A continuous Ar ion laser (488 nm) excites the fluorescent tracer and its fluorescence is detected by a spectrometer attached to a cooled, charge-coupled device (CCD) camera... 

T. A. Kelly, C. A. Hunter, D. C. Schindele, and B. V. Pepich, Aluminum phthalocyanine-streptavidin New, sensitive fluorescent tracer for immunoassay, Clin. Chem. 37, 1283-1286 (1991). 

Flow cytometry (FCM) is a high-precision technique for rapid analysis and sorting of cells and particles. In theory, it can be used to measure any cell component, provided that a fluorescent tracer is available that reacts specifically and stoichiometrically with that constituent. The technique provides statistical accuracy, reproducibility, and sensitivity. 

This protocol uses propidium iodide (PI) as the fluorescent tracer for DNA content (3-6). PI binds to both double-stranded DNA and double-stranded RNA. Therefore, RNase will be used to reduce the double-stranded RNA resulting in only DNA staining. For alternative DNA-specific ligands and dyes, see Chapter 30. 

Turner Designs Inc. [Online], Fluorescent Tracer Studies, available http //www.tumerdesigns.com/t2/doc/appnotes/ tracer dye.html accessed 20 November 2009. 

Fig. 12 (a) Chemical structures of the fluorescent tracers synthesized for P-lactam antibiotic analysis PAAP [25,5/f, 6/ ]-3,3-dimethyl-7-oxo-6-[(pyren-l-ylacetyl) amino -4-thia-l-azabicyclo 3.2.0 heptane-2-carboxylic acid PBAP [2S,5/ ,6/J]-3,3-dimethyl-7-oxo-6-[(4-pyren-lylbutanoyl]amino]-4-thia-l-azabicyclo[3.2.0] heptane-2-carboxylic acid PAAM [2S,5/ ,6/ ]-3,3-dimethyl-7-oxo-6-( (2/f)-2-phenyl-2-[(pyren-l-ylacetyl)amino]ethanoyl amino)-4-thia-l-azabicyclo[3.2.0] heptane-2-carboxylic acid PBAM [2S,5/f,6/f]-3,3-dimethyl-7-oxo-6-( (2/f)-2-phenyl-2-[(pyren-l-ylbutanoyl)amino]ethanoyl ainino) l-thia-l-azabicyclo... 

Preliminary results using a fluorescent tracer, which was added to the spray tank at the same time as the pesticide (Guthion WP), indicated that the distribution of the tracer, and presumably the pesticide, was not uniform, emphasizing the difficulty in the placement of the patches (2) This tracer technique is currently being evaluated as a tool for quantitative exposure estimation. This could result in a more realistic measurement of pesticide contact on the skin and minimize the reliance on extrapolation from the patch data. 

M 4] [P 3] Using the improved EKI mixer device, mixing times of about 2.5 s are obtained [25]. This was deduced from time-resolved images showing the point when a randomly distribution of a fluorescence tracer is achieved (see also Flow perturbation upon alternating (AC) current operation above for the lower performance of the first-generation device). 

Sucrose or glycerol solutions were contacted with the same solutions containing a fluorescent tracer [48]. Both streams were fed with the same flow rate. Fluorescence microscopy was used for flow monitoring. 

Figure 17 An example of PIV/LIF/SIT-measured velocity field together with the bubble shapes and positions in an upward bubbly flow (a) PIV image with fluorescent tracer particles (b) SIT snapshot with bubble shadow images at the same instant as (a) and (c) velocity vector field together with detected bubbles reconstructed from (a) and (b) (Fujiwara et al, 2004b).

An open tubular capillary was used for the evaluation of the performance of the solvent gradient system. Fluoranthene, added to the mobile phase in the second reservoir served as a fluorescent tracer to indicate the percentage of this solvent constituting the final mobile phase. The time between the beginning of the linear portion of the voltage program and the onset of the increase in measured fluorescence... 

Figure 4.30 Helical falling-film microreactor (right). Flow of the liquid in the helical microchannel, visualized by injection of a fluorescent tracer (by courtesy of Elsevier and IMM) [266].

Benemann, J.R., Tillet, D.M. and Weissman, J.C. 1987. Microalgae biotechnology. Trends Biotechnol., 5, 47-53. Biomeda, 1986. Phycobiliproteins as fluorescence tracers. Biomeda News 1,1-12. 

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