2-Anilinonaphthalene-6-sulfonic acid

Anilinonaphthalene-6-sulfonic acid, 4, complexation with /S- or y-CD in the presence of alcohols was studied using steady-state and time-resolved fluorescence spectroscopy [62]. The /5-CD-4 fluorescence was decreased by... 

A few methods based on fluorescence have been described for biotin and avidin determinations. A first one is based on the quenching of the avidin tryptophan fluorescence by biotin upon binding (71). A second one involves the increase of the fluorescence of avidin labeled with fluorescein isothiocyanate upon binding of biotin (72). The latter technique has been applied to HPLC postcolumn detection of biotin (see below). The sensitivities are, respectively, 20 and 0.5 ng. Another method is based on the variation of the fluorescence polarization of a biotin-fluorescein derivative upon interaction with avidin (73). Minimal detectable concentrations reported were 5 ng for avidin and 0.1 ng for biotin (73). Mock et al. reported another technique relying on the displacement by biotin of the fluorescent probe 2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) (Fig. 10) when bound to avidin (74). The advantage of this method is obviously the large increase of fluorescence of 2,6-ANS when bound to avidin as compared to the unbound form in water solution. The detection limit was around 1 ng. This technique has also been applied to postcolumn detection of biotin (see below). 

One explanation that can be offered to explain the two Tc values obtained for PMA at low values of a is that they represent the independent rotation of small clusters of the polymer chain. The larger value of (approximately 50 ns) can be associated with a rotating spherical cluster of radius 3.8 nm and of polymer molecular weight equal to 19000. Rotating units of similar size have been observed when the probes 9-methylanthracene and 9,10-DMA are solubilized in the PMA hypercoil structure (15,16) and when the more polar fluorescent probes Rhodamine B ( ) and 1,8-anilinonaphthalene sulfonic acid (1,8-ANS) (28) are bound to PMA for a value of a equal to 0. The smaller rotating unit present in PMA and PAA whose value of Tj, is approximately equal to 5 ns (which corresponds to particles whose radii are approximately equal to 2 nm) may arise from the rotation of a small section of the chain which is just sufficient to surround the 9,10-DMA probe and protect it from unfavourable entropic interactions with water. This shorter T, was... 

Anilinonaphthalene-l-sulfonic Acid Ammonium Salt Reagent... 

Dipping solution Dissolve 100 mg of 8-anilinonaphthalene-l-sulfonic acid ammonium salt in a mixture of 40 ml caustic soda solution (c = 0.1 mol/1) and 57 ml of an aqueous solution containing 21 g citric acid monohydrate and 8 g sodium hydroxide per hter. 

Spray solution Dissolve 100 mg of 8-anilinonaphthalene-l-sulfonic acid ammonium salt in 100 ml water [1]. 

Anilinonaphthalene-l-sulfonic acid ammonium salt, which scarcely fluoresces in aqueous solution, is stimulated to intense fluorescence by long-wavelength UV light (A = 365 run) if it is dissolved in nonpolar solvents or adsorptively bound to nonpolar molecular regions [3]. 

In 2000, the first example of ELP diblock copolymers for reversible stimulus-responsive self-assembly of nanoparticles was reported and their potential use in controlled delivery and release was suggested [87]. Later, these type of diblock copolypeptides were also covalently crossUnked through disulfide bond formation after self-assembly into micellar nanoparticles. In addition, the encapsulation of l-anilinonaphthalene-8-sulfonic acid, a hydrophobic fluorescent dye that fluoresces in hydrophobic enviromnent, was used to investigate the capacity of the micelle for hydrophobic drugs [88]. Fujita et al. replaced the hydrophilic ELP block by a polyaspartic acid chain (D ). They created a set of block copolymers with varying... 

The search for more rapid and sensitive methods of protein detection after electrophoresis led to the development of fluorescent staining techniques. Two commonly used fluorescent reagents are fluorescamine and anilinonaphthalene sulfonate. New dyes based on silver salts (silver diamine or silver-tungstosilicic acid complex) have been developed for protein staining. They are 10 to 100 times more sensitive than Coomassie Blue (Fig. 4.7). 

The more sensitive method of Rees et al. (R6) requires about 7 jul plasma per ml dye solution (6 mg l-anilinonaphthalene-8-sulfonic acid per liter phosphate buffer, pH 7.6). The fluorescence intensity of the plasma-dye mixture is measured (activation peak 370 nm, fluorescent peak 485 nm) and the albumin concentration obtained from a standard curve. The dye is stable and has low blank fluorescence a filter fluorimeter is satisfactory for the determination. Bile pigments in excess of about 5 mg/100 ml plasma interfere with the method low results are presumably caused by competition between bilirubin and dye for binding. Bovine albumin has been stated to produce more intense fluorescence with anilinonaphthalene-sulfonate than human albumin (R6). This requires confirmation, since dt... 

Both pre- and post-electrophoresis staining can be done. However, post-staining usually is preferred, because it does not alter the separation. Anilinonaphthalene sulfonate can detect 20 pg of protein. Dansyl chloride reacts with amines, amino acids, proteins, and phenols. Exposure of protein for 1 to 2 minutes at 100 °C to dansyl chloride produces a fluorescence capable of detecting 8 to 10 ng. Similarly, exposing primary amine-containing compounds to fluor-escamine at room temperature and an alkaline pH permits the detection of 6 ng of myoglobin. A newly popular compound is 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF). It can detect 1 ng of protein, and it is linear from 1 to 500 ng. 

Collini, M. D Alfonso, L. Molinari, H. Ragona, L. Catalano, M. Baldini, G. Competitive binding of fatty acids and the fluorescent probe 1-8-anilinonaphthalene sulfonate to bovine P-lactoglobulin. Protein Sci. 2003,12 (8), 1596-1603. 

Similarly, l-anilinonaphthalene-8-sulfonic acid (ANS) only emits in a hydrophobic environment, being almost completely quenched in aqueous solution. ANS and some other dyes, including 6-(p-toluidinyl)naphthalene-2-sulfo-nate, pyrene, l,6-diphenyl-l,3,5-hexatriene, fluorescein, and rhodamine derivatives attached to long acyl chains or to fatty acids that localize in the cellular membranes were used as probes for hydrophobic sites in proteins, protein folding, imaging of membranes of the cell, and solvent polarity. Pyrene-labeled fatty acids were used to detect the fusion of two membranes. When present in a membrane at sufficiently high concentrations, pyrene excimers (excited-state dimers) are formed that emit at 470 nm. Upon fusion with other membranes, probe concentration decreases, and excimer fluorescence is replaced by monomer fluorescence at 400 nm. This process can be monitored by ratiometric detection of pyrene labels. 

Spectral position and form of fluorescence bands are dependent on the molecular environment (neighbored molecules) and can be used to investigate adsorption, complexation, interaction, or aggregation processes. Special fluorophores like pyrene and l-anilinonaphthalene-8-sulfonic acid (ANS) exhibit dramatic changes of their fluorescence spectra when changing the polarity of their environment and were therefore often applied as fluorescence probes. 

---