Lipophilic dyes

Lipophilic dyes in aqueous alcoholic solutions can be employed in an analogous manner [92, 93]. They are enriched at the zones of lipophilic substances, so that these appear deeply colored on a pale background. This does not apply to fatty acids with less than 12 C atoms [94]. 

FIGURE 6.19 Circular chromatography of dyes on precoated silica gel high-performance TLC plate lipophilic dyes, mobile phase hexane-chloroform-NH3, 70 30. (From Ripphahn, J. and Halpaap, H., HPTLC High Performance Thin Layer Chromatography, Zlatkis, A. and Kaiser, R. E., Eds., Elsevier, Amsterdam, 1977, pp. 189-221. With permission.)... 

The relatively nonpolar squaraine rotaxane 14c was found to interact with cells in a very similar way to the well-known lipophilic dye Nile Red this probe rapidly accumulates at lipophilic sites inside a living cell, such as the endoplasmic reticulum and intracellular lipid droplets [55], The red emission band for probe 14c is quite narrow and permits the acquisition of multicolor images. It displayed high chemical stability and low toxicity. 

Purification is often required for the beads obtained by the techniques described above since undesired substances such as surfactants, coupling agents, etc. need to be removed. This is also valid for dye molecules noncovalently adsorbed on the surface of the beads since they usually have different properties (sensitivity, cross-talk to other analytes, leaching, etc.) compared to the molecules located in the core. The dye-doped beads can be purified by repeated precipitation which is achieved by adding salts (typically sodium chloride). In certain cases (typically for large beads) the addition of salts is not necessary so that the beads can be isolated by centrifugation. Washing with ethanol often helps remove lipophilic dye molecules adsorbed on the surface provided that the polymer is not swellable. Alternatively, dialysis can be useful especially if a hydrophilic water-soluble indicator is covalently coupled to the bead surface. 

The experiments reviewed in Section 13.1 demonstrated in detail that LCM can be labeled with lipophilic fluorescent dye and still retain their tumor-targeting properties. Furthermore, these lipophilic-dye-labeled LCM were shown to become internalized by tumor cells both in vitro and in vivo. This tumor-targeting ability of dye-labeled LCM, and their in vivo persistence at the tumor site and/or within the tumor cell for many minutes, suggested a potential use of LCM as a targeted drug-delivery agent or vehicle (ref. 532). Thus, a search was started for lipophilic anticancer drugs (preferably already FDA-approved for clinical use) that could be incorporated into the LCM and carried specifically to the tumor site. 

Abstract A novel colorimetric method, digital color analysis (DCA), was proposed using a digital color analyzer and was applied to various quantitative analyses using chromatic-ity coordinates and suitable sensors for visual colorimetry based on the characteristics of human visual perception by virtual simulations based on digital color information. On the basis of DCA, we developed a visual colorimetric sensor for Li+, NH4+ and protein determination by the mixing of two kinds of lipophilic dyes, whose optimum mixing ratio... 

Currently, patch clamping (Jauch and Lauger, 1986 Bimir et al., 1991 Parent et al., 1992a,b) has all but replaced lipophilic dyes and lipophilic cations as the method of choice in measuring membrane potential. The latter studies also address the site of action of the membrane potential in coupled transport and show that the... 

In the work of Loomeijer and work on similar lines carried out in the author s laboratory no evidence was found for the presence in important amounts of the common fatty esters, phospholipids, or steroids in purified preparations of elastin in these circumstances there seems to be little reason to classify elastin with the lipoproteins. The uptake of lipophilic dyes, which has been mentioned by several authors as indicating a lipoprotein character, can as well be explained by the presence of massive nonpolar radicals in the fluorescent prosthetic group, as described by Loomeijer, or to interactions with lipophilic sections of the peptide chain due to the large concentrations of nonpolar amino acids such as valine, the leucines, and phenylalanine. 

Phosphorylated l,6-diphenyl-l,3,5-hexatriene (DPH) (31), a lipophilic dye consisting a fiuorophore attached to a phosphate diester was prepared and its... 

Clofazimine is a strongly lipophilic dye and accumulates in tissues, especially fat, bile, macrophages, the reticuloendothelial system, and skin. This is the basis of adverse reactions, including skin discoloration (1). Lymphedema (2), diminished sweating, and reduced tearing have been observed (3). 

Aromatic hydrocarbons, herbiddes, hydrazines, insectiddes, metal ions, fat-soluble vitamins, lipids, lipophilic dyes, PAHs... 

Figure 8. Separation of lipophilic dyes on UTLC-plate...

O Brien, J. and Lummis, S.C. R. (2004) Biolis-tic and diolistic transfection using the gene gun to deliver DNA and lipophilic dyes into mammalian cells. Methods 33 121-125. 

That these sensors have practical significance is illustrated by the publications of Hisamoto et al. and Wang et al, which have described the measurement of common ions directly in serum [228, 229]. Alternatively, the complexation of the metal ion may influence the partition of the lipophilic dye in the membrane phase, which can affect the fluorescence yield of the dye. Recently this principle has been demonstrated with potential sensitive dyes by Wolfbeis and Mohr [231, 232]. This approach is also applicable to the sensing of neutral species and anions, as exemplified by sensor matrices for 2-phenetylamine [233] and nitrate [234]. 

Nuclear-associated vesicles (either chromatin-bound or fused into an envelope) can be labeled. Alternatively, vesicles can be prelabeled prior to nuclear assembly reactions. To label chromatin-associated vesicles, a 10-/il extract containing nuclei is mixed with 10 ju.1 of DiOC6 or DilCis, each at 20 /xg/ml in egg lysis buffer (stock B), and incubated at room temperature for 20 min. Samples are visualized under the fluorescence microscope using the appropriate filter sets. Nuclear DNA can be simultaneously labeled at a final concentration of 0.1 /u.g/ml Hoechst 33342. If desired, samples can be fixed and stained simultaneously. A IO-/1I sample is mixed with 10 /x.1 of 7% paraformaldehyde containing 20 ju.g/ml of either of the lipophilic dyes. 

LE state. See Locally excited state (LE state) Light harvesting (LH), 230—231 Linear Response formalism (LR formalism), 211 Lipophilic dye, 221—222 Locally excited state (LE state), 221—222 LR formalism. See Linear Response formalism (LR formalism)... 

Therefore, a viable-colony staining method has been developed which involves the direct inclusion of the lipophilic dyes Nile red or Nile blue A in the agar medium. This method requires a very low dye concentration, does not affect cell growth and obviates the need to produce master plates. However, the viable-colony method is more applicable for screening Gram-negative bacteria than Gram-positive bacteria [8]. Moreover, this method has its own drawbacks such as the requirement for appropriate carbon sources for the cultivation... 

An aqueous solution of a hydrophilic dye, such as methylene blue, can be used in place of water. The background turns blue, whereas pale blue spots occur at the locations that are dry. Lipophilic dyes in aqueous alcohol solution have been used to reverse the process, producing darkly colored zones at the position of the lipophilic substances on a less-colored background (Jork et al., 1990). 

Basic TLC design is illustrated here with the aid of a three-component lipophilic dye mixture (Mallinkrodt dye 3082, containing 1 ig/(J.l of each dye), containing butter yellow, Sudan red G, and indophenol blue. Various other lipophilic dyes are available commercially, including four- to six-component mixtures. For further information, consult the Analtech catalog. One of Stahl s (1969) major contributions to TLC was the introduction of standard dyes to test basic TLC procedures. 

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