Fluorescence-based

Applications of the oxalate-hydrogen peroxide chemiluminescence-based and fluorescence-based assays with NDA/CN derivatives to the analysis of amino acids and peptides are included. The sensitivity of the chemiluminescence and fluorescence methods is compared for several analytes. In general, peroxyoxalate chemiluminescence-based methods are 10 to 100 times more sensitive than their fluorescence-based counterparts. The chief limitation of chemiluminescence is that chemical excitation of the fluorophore apparently depends on its structure and oxidation potential. 

It is appropriate at this juncture to illustrate the power of chemiluminescence in an analytical assay by comparing the limits of sensitivity of the fluorescence-based and the chemllumlnescence-based detection for analytes in a biological matrix. The quantitation of norepinephrine and dopamine in urine samples will serve as an illustrative example. Dopamine, norepinephrine, and 3,4-dihydroxybenzy-lamine (an internal standard) were derivatized with NDA/CN, and chemiluminescence was used to monitor the chromatography and determine a calibration curve (Figure 15). The limits of detection were determined to be less than 1 fmol injected. A typical chromatogram is shown in Figure 16. 

Flavonoids, physiological and nutritional aspects, 14 (1977) 285 Fluorescence-based assays, 43 (2005) 19 Fluoroquinolone antibacterial agents,... 

Fluorescence-based methods do not directly measure ionic current but, rather, measure either membrane-potential-dependent or ion-concentration-dependent changes of fluorescence signals (from fluorescent dyes loaded into the cytosol or cell membrane) as a result of ionic flux. Because fluorescence-based methods give robust and homogeneous cell population measurement, these assays are relatively easy to set up and achieve high throughput. 

Wu P, Norland TM, Gildea B, McLaughlin LW (1990) Base stacking and unstacking as determined from a DNA decamer containing a fluorescent base. Biochem 29 6508-6514... 

Sharifzadeh M, Bernstein PS, and Gellermann W (2006), Non-mydriatic fluorescence-based quantitative imaging of human macular pigment distributions, J. Opt. Soc. Am. A 23 2373-2387. 

Time-resolved IR spectra of similar peptides following a laser-excited temperature jump showed two relaxation times, unfolding 160 ns and faster components <10 ns (Williams et al., 1996). These times are very sensitive to the length, sequence, and environment of these peptides, but do show that the fundamental helix unfolding process is quite fast. These fast IR data have been contrasted with Raman and fluorescence-based T-jump experiments (Thompson et al., 1997). Raman experiments at various temperatures have suggested a folding in 1 /xs, based on an equilibrium analysis (Lednev et al., 2001). But all agree that the mechanism of helix formation is very fast. 

Ohuchi Y, Katayama Y, Maeda M (2001) Fluorescence-based sensing of protein kinase A activity using the dual fluorescent-labeled peptide. Anal Sci 17 il465—i 1467... 

Fluorescence-based bulk viscosity measurement is one application that advertises itself almost immediately, particularly with julolidine-derived molecular rotors where the quantum yield is widely independent from solvent polarity. Solving (5) for r] and assuming proportionality of quantum yield and emission intensity leads to (13),... 

Milich KN, Akers W, Haidekker MA (2005) A ratiometric fluorophotometer for fluorescence-based viscosity measurement with molecular rotors. Sensor Lett 3 237-243... 

MapMarker sets of fluorescently labeled DNA fragments for sizing standards and compatible with (fluorescent-based) separation instruments systems. 

Product and services of interest include genomics, proteomics, custom research and services, and instruments, accessories, consumables and software. PerkinElmer proprietary technologies include time-resolved fluorescence which is employed in the sensitive Wallac DELFIA system and Wallac LANCE homogeneous assay system, and fluorescence polarization, [FP]2 , a robust fluorescence-based technique for receptor binding assays that is both fast and easy-to-use. 

Kroneis H.W., Marsoner H.J., A fluorescence-based sterilizable oxygen probe for use in bioreactors, Sensor Actuat B-Chem 1983 4 587. 

Wolfbeis O.S., Fluorescence-based ion sensing using potential-sensitive dyes, Sensor ActuatB-Chem 1995 29 140. 

Optical fibres composed of plastics are also transparent in the visible spectral region but optical losses reach 102 - 103 dB/km13. Their refractive index varies from 1.35 to 1.6 depending on the kind of polymer used (e.g. polymethymethacrylate PMMA -1.49). The chemical resistance is much worse than that of silica fibres and thermal stability is incomparable. On the other hand, low temperature processes of plastic fibre preparation allow us mix the starting polymer with organic dyes which enables the production of luminescent fibres suitable e.g. for fluorescence-based sensing13. 

As it has been discussed above, fluorescent-based sensors have found application to the analysis of every possible species from gases (02, C02,... 

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