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1.
The interaction between 2-p-toluidinylnaphthalene-6-sulfonic acid (TNS), a hydrophobic fluorescent probe, and poly(2-vinylpyridinium) polyions (PVP) has been investigated by fluorescence spectroscopy. Both the effect of the charge and the concentration of PVP on the fluorescence behavior of TNS indicate that interaction between TNS and hydrophobic sites present in the PVP chain is responsible for the observed phenomena. It is shown that PVP which exists with predominant hydrophobic regions leads to TNS fluorescence, but some residual charge must be present to facilitate the penetration of the dye into the hydrophobic regions. Various situations existing in some polyelectrolyte systems are discussed. 相似文献
2.
Toru Takagishi Toshitsugu Hosokawa 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1925-1933
The copolymers of N-vinyl-2-pyrrolidone and 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, 2-dimethylaminoethyl acrylate, or 2-dimethylaminopropyl acrylamide have been prepared. Studies were made of the binding of a “binding probe,” methyl orange, by the copolymers in aqueous solution. The first binding constants accompanying the binding were evaluated. Furthermore, the intensity of fluorescence of a hydrophobic fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate, in the presence of these polymers was investigated. The nature and phenomena of dye binding and hydrophobic fluorescent probe binding with the polymers are discussed. 相似文献
3.
Richard L. Reeves Shelley A. Harkaway Alena R. Sochor 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2427-2441
The binding of two ionic azo dyes (4-phenylazo-1-naphthol mono-and disulfonate) and a fluorescent probe (2-p-toluidinonaphthalene-6-sulfonic acid, TNS) to poly(vinylpyrrolidone) (PVP) was studied to obtain information on the nature of the interaction, binding isotherm, and binding site. Sorption of the dyes followed a Langmuir isotherm only at low polymer saturation. Apparent cooperativity in binding was seen at higher saturation. The polymer had a higher intrinsic binding constant but lower binding capacity for the doubly charged dye than for the structurally similar singly charged dye. Both dyes consisted of tautomeric mixtures of hydrazone and azonaphthol forms in equilibrium in the bound and unbound state. The preferential binding of the azonaphthol tautomer of the disulfonate was highly exothermic and accompanied by an entropy decrease. The binding of the hydrazone form was less favored by 1.8 kcal/mol, was weakly exothermic, and accompained by an entropy increase. Increased preference for the azonaphthol tautomer accompanied chain extension from charging the polymer. Chain extension had no effect on the emission frequency of bound TNS. Large differences in binding capacities for similarly charged dyes indicated the existence of specific dye-site interactions. Arguments are presented against nonspecific hydrophobic interactions as predominant forces responsible for binding. 相似文献
4.
Toru Takagishi Toshitsugu Hosokawa Yasumichi Hatanaka 《Journal of polymer science. Part A, Polymer chemistry》1989,27(1):1-13
The pH dependence of the interaction of poly(2-dimethylaminoethyl methacrylate) and copolymers of 2-dimethylaminoethyl methacrylate and N-vinyl-2-pyrrolidone with methyl orange, 2-p-toluidinylnaphthalene-6-sulfonate (TNS), and 1,6-diphenyl-1,3,5-hexatriene (DHT) was studied by equilibrium dialysis and fluorescence measurements at pH's 7–10. The first binding constant accompanying the binding of methyl orange and TNS by the polymers, in particular the homopolymer, shows a maximum around pH 8 and maximal fluorescence intensity of TNS is obtained around pH 8.5 in the presence of the polymers. To elucidate these observations the pH-induced conformational changes of the homopolymer were examined by potentiometric titration and viscosity measurements and the thermodynamic parameters that accompany the binding were calculated. The polymer was found to change from an extended coil at lower pH to a compact coil at higher pH. The electrostatic attraction between the sulfonate group of the small molecule and the protonated nitrogen atoms on the polymer is increased at lower pH and the hydrophobic interaction between the hydrophobic moieties of the polymer and the small molecule is enhanced at higher pH. The results obtained for the dye binding and fluorescence intensity were discussed in terms of the electrostatic and hydrophobic interactions. 相似文献
5.
Toru Takagishi Young Joo Kim Toshitsugu Hosokawa Keiji Morimoto Kenji Kono 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):365-371
The copolymers of methyl quaternized 2-dimethylaminoethyl acrylate and styrene, 2-vinyl naphthalene, acrylic acid iso-octyl ester, or acrylic acid n-butyl ester have been prepared. Studies were made of the binding of a “binding probe,” methyl orange, by the copolymers in aqueous solution. The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. Furthermore, the intensity of fluorescence of a hydrophobic fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate, in the presence of these polymers was investigated. In addition, the fluorescence spectra of monomer and excimer emissions of the polymers with aromatic residues were measured. The excimer/monomer fluorescence intensity ratio was studied in the presence of various additives such as methyl orange, urea, methanol, and NaCl to gain an insight into the nature of microdomains in the polymer. The nature and phenomena of dye binding and hydrophobic fluorescent probe binding with the polymers are discussed. © 1993 John Wiley & Sons, Inc. 相似文献
6.
Fluorescent amphiphilic polymers were produced by grafting different types and levels of hydrophobic pendant groups with intrinsic fluorescent properties (fluorenylmethoxy carbonyl (Fmoc), dimethylamino‐1‐naphthalenesulfonyl (Dansyl), and naphthalene (Naphth) to a water soluble homopolymer backbone, polyallylamine (PAA). Non‐fluorescent hydrophobic pendant group (cholesteryl moieties) were also grafted onto PAA. The polymers were characterized with elemental analysis, NMR and FTIR spectroscopy. All polymers formed self‐assemblies by probe sonication in water with sizes ranging from 120 to 199 nm and TEM images showed the presence of spherical particles. The critical aggregation concentration (CAC) varied from 0.093 to 1.5 mg ml?1 depending on the type of hydrophobic pendant groups. The Cholesteryl and Dansyl polymers showed the presence of one CAC while the Fmoc and Naphth grafted polymers revealed the presence of two CACs. The first CAC observed was possibly due to intermolecular aggregation while the second CAC at the higher polymer concentration was the result of excimer formation revealed by their fluorescent spectra. We reasoned that Naphth and Fmoc aromatic pendant groups possess a flat stereochemistry, thus allowing π–π stacking at higher concentrations. The presence of the N‐dimethylamino group in the Dansyl moiety gives rise to a 3D structure, thus hindering any stacking. The understanding of the supramolecular assemblies formed by these fluorescent amphiphilic polymers will aid in the engineering of advanced materials with superior functionality for biomedical applications. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
7.
2-(p-toluidino)-6-naphthalene sulfonate (TNS) is a probe that fluoresces strongly when bound to certain proteins and polymers,
but weakly in aqueous solution. Absorption and fluorescence spectroscopy were used to study the interaction of TNS with native
amylopectin potato starch (NApS) and cationized amylopectin potato starch (CApS) in aqueous solution. The anionic TNS binds
to CApS at a single type of binding site, with an affinity which has both electrostatic and nonelectrostatic contributions
(including hydrogen bonding), whereas binding to NApS occurs at the same type of site but only by nonelectrostatic means.
The affinity to CApS decreases strongly with increasing salt concentration, due to screening of the electrostatic attraction,
whereas with NApS increasing salt concentration slightly enhances the binding affinity, most likely due to screening of a
weak repulsive interaction between TNS and phosphate residues on NApS. The association constant for binding of TNS to CApS
in 5 mM NaCl is 110 ± 20 M−1. This comparatively weak binding makes TNS a useful probe in kinetic investigations of the flocculation of anionic silica
particles by CApS.
Received: 14 August 1998 Accepted in revised form: 4 December 1998 相似文献
8.
Wang ZJ Ren LX Zhao YQ Li GT Duan L Liang AH Yang BS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(4):892-897
The interaction between 2-p-toluidinylnaphthalene-6-sulfonate (TNS) and ciliate Euplotes Octocarinatus centrin (Cen) has been studied by fluorescence spectroscopy. The binding constants of TNS with Cen were measured at different temperature in the 0.01M Hepes, pH 7.4. The binding process is exothermic and involves a positive entropy change. The negative value of enthalpy predominately contributes to the negative free energy of binding between TNS and Cen. The salt (KCl) increases the association constant of TNS and Cen. These results and resonance light scattering experiment suggest that the binding force between TNS and Cen is hydrophobic. The distance (r) between TNS and tryptophan of mutant G115W, which sheds more insight into the binding of TNS to Cen, was determined as 4.85nm based on F?rster non-radiative energy transfer theory. 相似文献
9.
2-(p-toluidino)-6-naphthalene sulfonate (TNS) is a probe that fluoresces strongly when bound to certain proteins and polymers,
but weakly in aqueous solutions. The reversible association of TNS is used to monitor the binding of anionic nanosized silica
particles (NSP) to cationic potato amylopectin starch (CApS) through the decreasing fluorescence emission as TNS is competitively
released by the particle binding. Steady-state fluorescence measurements at different mixing ratios of CApS and NSP provide
data on the equilibrium binding. The isotherm derived is used to establish the fact that the most efficient flocculation between
CApS and NSP occurs when the polymer coils are nearly saturated by NSP, but still have positively charged parts left. This
supports a patch-flocculation mechanism. Stopped-flow experiments show that NSP binding to CApS occurs within a few milli
seconds. This observation allows turbidity changes which occur on longer timescales to be ascribed to particle-decorated polymers
undergoing changes in the conformation or aggregation.
Received: 14 August 1998 Accepted in revised form: 4 December 1998 相似文献
10.
Marcelo H. Kravicz Debora T. Balogh Mrityunjoy Kar Stefanie Wedepohl Maria Vitoria L. B. Bentley Marcelo Caldern 《Macromolecular bioscience》2019,19(10)
The development of polymers with low toxicity and efficient gene delivery remains a significant barrier of nonviral gene therapy. Modification and tuning of chemical structures of carriers is an attractive strategy for efficient nucleic acid delivery. Here, polyplexes consisting of plasmid DNA (pDNA) and dodecylated or non‐dodecylated polysuccinimide (PSI)‐based polycations are designed, and their transfection ability into HeLa cells is investigated by green fluorescent protein (GFP) expressing cells quantification. All cationic polymers show lower cytotoxicity than those of branched polyethyleneimine (bPEI). PSI and bPEI‐based polyplexes have comparable physicochemical properties such as size and charge. Interestingly, a strong interaction between dodecylated polycations and pDNA caused by the hydrophobic moiety is observed in dodecylated PSI derivatives. Moreover, the decrease of GFP expression is associated with lower dissociation of pDNA from polyplexes according to the heparin displacement assay. Besides, a hydrophobization of PSI cationic derivatives with dodecyl side chains can modulate the integrity of polyplexes by hydrophobic interactions, increasing the binding between the polymer and the DNA. These results provide useful information for designing polyplexes with lower toxicity and greater stability and transfection performance. 相似文献
11.
Abstract—
The interaction between human α1 -acid glycoprotein (orosomucoid) and the fluorescent probe, 2- p -toluidinylnaphthalene-6-sulfonate (TNS) has been studied. An association constant of 16.7 (±3) X 103 M -1 was obtained for the complex at 20°C with a stoichiometry of 1:1. From the effect of temperature on the binding process, the standard enthalpy change for the binding is calculated to be ΔH0 = -18 ± 3 kJ mol-1 and the standard entropy change ΔS0 = 19 ± 12 J K-1 mol-1 . The tryptophan fluorescence of the protein can be described by a sum of three exponentials. Upon TNS binding, the average fluorescence lifetime of the protein in the complex changes much less than the fluorescence intensity. The bound TNS is therefore a very efficient acceptor for the protein fluorescence. The TNS bound to orosomucoid presents two fluorescence lifetimes 1 1 and 4.3 ns. The possible origins of the two lifetimes are discussed. 相似文献
The interaction between human α
12.
13.
Toru Takagishi Yoshiro Nakata Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1974,12(4):807-816
The binding of methyl orange, ethyl orange, and propyl orange by polycations involving various apolar pendant groups such as methyl, ethyl, benzyl, or dodecylbenzyl groups has been examined quantitatively by an equilibrium dialysis method at 5, 15, 25, and 35°C. The first binding constants and the thermodynamic parameters in the course of the binding have been calculated. The favorable free energy of the binding is accompanied by an entropy gain and an exothermic enthalpy change. The shorter the alkyl chain of the dyes or the polymers, the more negative is the enthalpy change and hence the smaller is the entropy change. Furthermore, an increase in binding affinity can be created in the polycation upon introduction of hydrophobic groups. In particular, the binding ability of the polycation containing a dodecylbenzyl group for methyl orange is almost 300-fold that of bovine serum albumin. Therefore it is clear that hydrophobic interactions, as well as electrostatic ones, are involved in the binding. 相似文献
14.
Debapriya Banerjee Sachin Kumar Srivastava Samir Kumar Pal 《The journal of physical chemistry. B》2008,112(6):1828-1833
In the present study, the interaction of two structurally related proteolytic enzymes trypsin and alpha-chymotrypsin (CHT) with 4',6-Diamidino-2-phenylindole (DAPI) has been addressed. The binding of DAPI to CHT has been characterized by steady-state and picosecond time-resolved spectroscopic techniques. Enzymatic activity of CHT and simultaneous binding of the well-known inhibitor proflavin (PF) in the presence of DAPI clearly rule out the possibility of DAPI binding at the catalytic site of the enzyme. The spectral overlap between the emission of DAPI and absorption of PF offers the opportunity to explore the binding site of DAPI using F?rster resonance energy transfer (FRET). FRET studies between DAPI and PF indicate that DAPI is bound to CHT with its transition dipole nearly perpendicular to that of PF. Competitive binding of DAPI with another fluorescent probe 2,6-p-toluidinonaphthalene sulfonate (TNS), having a well-defined binding site, indicates that DAPI and TNS bind at the same hydrophobic site of the enzyme CHT. The difference in the interactions of two well-studied, structurally similar enzymes with the same molecule may find its application in the design of specific substrate mimics or inhibitors of the enzymes. 相似文献
15.
C. Damas M. Adibnejad A. Benjelloun A. Brembilla M. C. Carré M. L. Viriot P. Lochon 《Colloid and polymer science》1997,275(4):364-371
Cationic amphiphilic polymers (e.g. polyvinylpyridinium bromides and polyvinylimidazo-lium bromides) adopt a compact coiled
form in aqueous solutions. In the case of former polymers, the resulting hydrophobic microdomains are evidenced only by fluorescence
spectroscopy if a molecular rotor (DMAC) is used as a fluorescent probe, while the behaviour of the latter can be studied
in aqueous solution by using both types of fluorescent probes, i.e., pyrene and the molecular rotor. The purpose of the present
investigation deals with a comparative study between the magnitude of the local viscosity and the polarity of the hydrophobic
microdomains generated by poly(3-hexadecyl-1-vinylimidazolium bromide) in an aqueous medium using pyrene and DMAC as fluorescent
probes. Moreover, the results are compared with the data obtained with micelles of conventional surfactants such as the homopolymer
repetitive unit model and CTAB.
Received: 3 June 1996 Accepted: 29 September 1996 相似文献
16.
Katsuhiko Ariga Ryutaro Tanaka Naoko Takagi Jun-Ichi Kikuchi 《Supramolecular chemistry》2013,25(2):87-94
In order to develop a supramolecular receptor through a self-assembling process, a site-specific host and an inclusion-type host were mixed as a Langmuir monolayer, and guest binding and pressure-induced fluorescence emission were investigated. A guanidinium amphiphile and several cyclophanes carrying hydrophobic moieties were used as the host molecules; molecular recognition of an aqueous fluorescent guest, 6-p-toluidino-2-naphthalenesulfonic acid (TNS) by binary mixed receptor monolayers was evaluated by a surface pressure-molecular area (π-A) isotherm and a surface fluorescence measurement. An apparent increase in fluorescence intensity was observed when the mixed monolayers of the guanidinium and cyclophane amphiphiles were compressed on an aqueous TNS solution. In contrast, single-component monolayers of the guanidinium or the cyclophane did not show a significant increase in fluorescence emission. In the mixed monolayers, the guest TNS would be bound to the interface by strong electrostatic interaction with the guanidinium, and inclusion of the formed complex probably suppresses the quenching effect in polar medium and/or self-quenching. Experiments with various mixing ratios of these components suggest selective formation of an equimolar cooperative receptor of the guanidinium and the cyclophane. Investigation of the cyclophane structures by fluorescence emission and a competitive binding experiment with another guest were also carried out. 相似文献
17.
The aim of this work was to envisage a new analytical fluorescent method to study the molecular interactions between cations and negatively charged lipid droplets contained in total parenteral nutrition (TPN) admixtures. For this purpose, two fluorescent probes were tested: 9-diethylamino-5H-benzo[alpha]phenoxazine-5-one, commonly named nile red (NR), and 2-(p-toluidinyl)-naphthalene-6-sulfonate (TNS). NR, a neutral molecule, and TNS, an anionic one, are both polarity probes. Their fluorescence emission was enhanced in an apolar environment. They were used at 1 and 2.5 muM, respectively. Results showed that scattered light was very intense in weak aqueous dilution (1/10 vv(-1)) of fat emulsion and appeared as an experimental constraint. The sensitivity of fluorescence measurement in fat emulsion samples was constantly higher for NR than for TNS. When calcium addition occurs, as in pharmaceutical practice, a dramatic increase of fluorescence emission signal was showed for TNS, but no effect was observed for NR. As a conclusion, it was pointed out that the interactions between lipid droplets and calcium ions were likely to take place at the interface of the droplet and that TNS was a more appropriate probe than NR to prove it. Thus, fluorescent probing appeared to be a convenient new analytical tool for the investigation of lipid-cations interactions in TPN mixtures. 相似文献
18.
1-Methyl-7-dimethylamino quinolinium tetrafluoroborate, a highly stable, highly fluorescent color-shifting mobility sensitive fluorescent probe was employed for detecting the glass transition and phase transitions, notably crystallization, in polymers and polymer blends. Glass transitions in amorphous and semi-crystalline polymers were detected by a change in gradient in emission wavelength λmax versus T plots. Crystallization resulted in discrete blue shifts in λmax versus T plots. Selective probing of PMMA in a PS/PMMA blend, down to a PMMA content of 1%, was demonstrated. Dielectric relaxation spectroscopy has established a clear link between the mobility of dipoles in PMMA and the emission wavelength of the fluorescent probe. 相似文献
19.
Takeshi Mori Yuuki Shiota Keiji Minagawa Masami Tanaka 《Journal of polymer science. Part A, Polymer chemistry》2005,43(5):1007-1013
We synthesized thermosensitive polymers by adding hydrophobic groups to the ends of a hydrophilic polyether, poly(ethylene oxide‐co‐propylene oxide). The cloud points of the polymers were controlled by the molecular weight of the polyether and the kind of hydrophobic end group. The polymers showed relatively sharp phase transitions, as observed by turbidimetry. The order of the cloud points of the polymers with various end groups did not follow that of the critical micelle concentrations of the polymers determined with fluorescence measurements with pyrene as a probe. The cloud points of the polymers linearly decreased with increasing concentrations of salts (Na2SO4 and Na3PO4). The slopes of the linear lines were almost constant, regardless of the kind of hydrophobic group and the molecular weight of the polyether. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1007–1013, 2005 相似文献
20.
The interaction of cationic (bio)polymers with DNA may cause the transfer of the intercalated cationic dye ethidium bromide from the double helix to solution. This effect is accompanied by probe fluorescence quenching. The effective displacement of ethidium from nucleic acid that has been discovered in the study of the cooperative electrostatic binding of DNA to salts of polymeric bases forms the basis of the fluorescent method useful for the investigation of polyelectrolyte complexes of DNA. By the example of a wide range of model polycations, this approach is shown to be fruitful for estimation of the cooperative character of interactions, construction of pH-dependent profiles of complexation reactions and competitive binding, and creation of systems with desired and controlled stability in aqueous-saline solutions. This evidence is of special importance for the design of polyelectrolyte means effective for delivery of genetic materials to the cell. 相似文献