Fluorescent attachment

Some commercial spectrophotometers have fluorescence attachments which allow the sample to be irradiated from an ancillary source and the resulting fluoresence to pass through the monochromator for spectral analysis. 

Absorption spectra were obtained with a Shimadzu model UV-3000 spectrophotometer in the split beam mode. Fluorescence spectra were scanned with the same instrument supplemented with a fluorescence attachment and a Hamamatsu R473 multiplier. A solution of 3 gL 1 rhodamine B in polyethyleneglycol was used as a photon counter. The digitized spectra were transferred to a Hewlett Packard microcomputer (model 226) for storage and processing. 

Vuilleumier JP, Keck E. Flourimetric assay of vitamin C in biological materials, using a centrifugal analyser with fluorescence attachment. J Micronutr Anal 1989 5 25-34. 

Burdett and Jones have described a convenient attachment that makes possible the determination of the fluorescence spectra with the Beckmann spectrophotometer. Upset 9 has suggested a versatile apparatus for auto matic recording of absolute fluorescence. In recent years, fluorescence attachments have become available for most commercial photo-electric spectrophotometers. 

Absorption spectrophotometry and spectrophotofluorometry were carried out with a Zeiss recording spectrophotometer (RPQ20), with a fluorescence attachment (ZFM 4C). 

The diameter of the particles can be chosen from several hundreds of nanometers to several microns. The PIV measurement uses an epi-fluorescent attachment of type Nikon G-2E/C (excitation filter for 540 nm, dichroic mirror for 565 nm and an emission filter for 605 nm). Both filters in the attachment have a bandwidth of 25 nm. 

Laser-based instrumeniatioa is preferred to focus the excitation radiation on the small capillary and to achieve the low detection limits available from intense sources. Laser-induced-fluorescence attachments are... 

Any serious effort at fluorimetric analysis of vitamin D was due to the Rochester group (Chen et al., 1964). They utilized the reaction of acetic anhydride-sulfuric acid in trichloroethane to induce fluorescence, the characteristics of which were then studied using a spectrophoto-fluorometer. The dry sterol was dissolved in 2.0 ml of 1 5 (20%) acetic anhydride-trichloroethane and was allowed to react with 75 pi of concentrated sulfuric acid in the dark for 40-60 minutes after which readings were taken in an Aminco-Keirs spectrophosphorimeter equipped with a fluorescence attachment. Optimum excitation/fluorescence wave-... 

Membrane-permeant fluorescent mitochondrial dyes, such as Rhodamine 123 (Rh 123 Sigma) or 4-Di-2-Asp (Molecular Probes), can be used to aid visualization of nerve terminals in the embryo (Yoshikami and Okun 1984). To label embryos, expose the embryos to the dye (5 pm) for 5 minutes and then remove the excess dye with several washes of saline. View the preparation with an epi-fluorescence attachment and appropriate filters. 

Stereomicroscope with transmitted light base, and fluorescence attachment (Leica Microsystems, Bannockburn, IL). 

Photoexcited fluorescence from spread monolayers may be studied [158,159] if the substance has both a strong absorption band and a high emission yield as in the case for chlorophyll [159]. Gaines and co-workers [160] have reported on the emission from monolayers of Ru(bipyridine)3, one of the pyridine ligands having attached C g aliphatic chains. Ruorescence depolarization provides information about the restriction of rotational diffusion of molecules in a monolayer [161], Combining pressure-area... 

The attachment of pyrene or another fluorescent marker to a phospholipid or its addition to an insoluble monolayer facilitates their study via fluorescence spectroscopy [163]. Pyrene is often chosen due to its high quantum yield and spectroscopic sensitivity to the polarity of the local environment. In addition, one of several amphiphilic quenching molecules allows measurement of the pyrene lateral diffusion in the mono-layer via the change in the fluorescence decay due to the bimolecular quenching reaction [164,165]. 

Liquid crystal polymers are also used in electrooptic displays. Side-chain polymers are quite suitable for this purpose, but usually involve much larger elastic and viscous constants, which slow the response of the device (33). The chiral smectic C phase is perhaps best suited for a polymer field effect device. The abiHty to attach dichroic or fluorescent dyes as a proportion of the side groups opens the door to appHcations not easily achieved with low molecular weight Hquid crystals. Polymers with smectic phases have also been used to create laser writable devices (30). The laser can address areas a few micrometers wide, changing a clear state to a strong scattering state or vice versa. Future uses of Hquid crystal polymers may include data storage devices. Polymers with nonlinear optical properties may also become important for device appHcations. 

Fig. 5. (a) Antibody 2 is added to test solution where some or all of becomes complexed with target, T. (b) A fiber-optic probe containing covalently attached target is insetted into the solution. Unbound binds to probe, (c) The probe is inserted into solution containing en2yme-modified detector antibody which binds to probe if any is attached, (d) The probe is inserted into a solution producing a fluorescent compound, which is then... 

When reaction is complete, the product consists of a mixture of DNA fragments of all possible lengths, each terminated by one of the four dye-labeled dideoxyribonucleotides. This product mixture is then separated according to the size of the pieces by gel electrophoresis (Section 26-2), and the identity of the terminal dideoxyribonucleotide in each piece—and thus the sequence of the restriction fragment—is identified simply by noting the color with which the attached dye fluoresces. Figure 28.8 shows a typical result. 

More recently, several groups have investigated electrostatic effects on the fluorescence quenching of hydrophobic chromophores covalently attached to various polyanions. The photophysics of the chromophores incorporated in the polyeletrolytes at small mole fractions is relatively simple, because no interaction is expected to occur between the incorporated chromophores. For this reason, most of the studies have focused on amphiphilic polyeletrolytes loaded with a low amount of hydrophobic chromophores. 

Fluorescent materials are very important in medical research. Dyes such as fluorescein (21) can be attached to protein molecules, and the protein can be traced in a biological system by exciting the fluorescein and looking for its emissions. The use of a fluorescent material allows the detection of much smaller concentrations than would otherwise be possible. Because fluorescent materials can be activated by radioactivity, they are also used in scintillation counters to measure radiation (see Box 17.2). 

Allyl56), vinylsilane62), acyl lactam63 , phosphonic ester64 , and many other functions have been attached to chain ends. Polymers fitted with dyes53) or fluorescent groups65) have been made in good yields. 

In an effort to understand how actin-actin interactions might be affected by the binding of the myosin head, and in order to gain more insight into the nature of the actin-myosin interface, we have investigated the nature of the kinetic actin-myosin intermediates involved in the process of S)-induced polymerization of G-actin. For this purpose, a variety of fluorescent probes (e.g., pyrene, NBD, AEDANS) have been covalently attached to the C-terminus of G-actin to probe the G-actin-S] interaction under conditions of tightest binding, i.e., in the absence of ATP. 

Nineteen bone samples were prepared for analysis of the trace elements strontium (Sr), rubidium (Rb), and zinc (Zn). The outer surface of each bone was removed with an aluminum oxide sanding wheel attached to a Dremel tool and the bone was soaked overnight in a weak acetic acid solution (Krueger and Sullivan 1984, Price et al. 1992). After rinsing to neutrality, the bone was dried then crushed in a mill. Bone powder was dry ashed in a muffle furnace at 700°C for 18 hours. Bone ash was pressed into pellets for analysis by x-ray fluorescence spectrometry. Analyses were carried out in the Department of Geology, University of Calgary. 

Distinguishing the two fibril components in TEM was achieved by attaching an antibody that binds to the fluorescent site, before adding another, gold-labelled. 

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