Immobilization Of Dyes Research Articles

Immobilization of anionic dyes by intercalation into hydrotalcite

The uptake of the diazo dye Acid Blue 113 by hydrotalcite (HT) and calcined hydrotalcite (CHT) was studied as a function of reaction time and dye equilibrium concentration. Equilibration is attained in ca. 15 h, irrespective of the sorbent. The kinetic profiles are however different; the uptake rate by HT is described by the pseudo-second order adsorption model, whereas sorption by CHT is accounted for by the Avrami's equation. Equilibrated sorption by HT and CHT complies, in both cases, with the Langmuir isotherm. Whereas the apparent affinity of CHT for the dye ( K L = 4.2 L mg −1) is about three times that of HT, its maximum sorption capacity is larger by a factor of 50; for CHT, q m is 2544 mg g −1. The difference reflects the operation of different uptake mechanisms. XRD data and pH measurements demonstrate that sorption by CHT takes place by intercalation, whereas removal by HT is solely due to adsorption. The uptake by CHT is also described by classical anion-exchange formalisms. It is shown that the applicability of the Langmuir model is, in the case of CHT, fortuitous. The high dye removal efficiency of HT, and especially of CHT, makes these materials excellent candidates to substitute activated carbons.

An optical sensor based on covalent immobilization of 1-aminopyrene using Au nanoparticles as bridges and carriers

A novel technique of covalent immobilization of indicator dyes for the preparation of optical sensors is investigated. Au nanoparticles are used as bridges and carriers for anchoring indicator dyes on the surfaces of quartz glass slides (the substrates). 1-Aminopyrene was covalently attached to the outmost surface of the substrates via silanization, attachment of Au particles, self-assembly of HS-(CH 2) 11-OH, and coupling of 1-aminopyrene using cyanuric chloride. Thus, an aminopyrene-immobilized optical sensor was prepared and employed for determining picric acid. This sensor shows practically no dye-leaching, rapid response, high selectivity, good reproducibility and reversibility. The linear response to picric acid covers the range of 9.55 × 10 −7 to 1.91 × 10 −4 mol l −1 with a detection limit of 7.8 × 10 −7 mol l −1. The covalent immobilization of 1-aminopyrene is an example of the proposed methodology which could be readily adaptable to other indicator dyes with primary amino groups.

Preparation of a novel fluorescence probe based on covalent immobilization by emulsion polymerization and its application to the determination of metronidazole

A novel method of preparing fluorescence particle probe by emulsion polymerization with covalent immobilization of indicator dye was described. A terminal double bond was attached to 3-amino-9-ethylcarbazole (AEC) via methacryloyl chloride, and the resultant compound was copolymerized with butyl methacrylate. The obtained polymer particles were used as a fluorescence probe, which is almost free of dye leaching, and has higher photostability and lower toxicity in comparison with free AEC. This probe holds great potential for the applications in intracellular measurements. In present study the prepared probe was used for the determination of metronidazole. The results revealed that the probe showed good selectivity and had a linear response to the analyte in the range from 2.0 × 10 −5 to 1.0 × 10 −3 mol l −1 with a detection limit of 9.0 × 10 −6 mol l −1.

Preparation of Affinity-Ligand Resins by Immobilization of Dyes on Polyhydroxyl Matrices Using a Direct Coupling Method

Preparation of Affinity-Ligand Resins by Immobilization of Dyes on Polyhydroxyl Matrices Using a Direct Coupling Method

Preparation of Affinity-Ligand Resins by Immobilization of Dyes on Polyhydroxyl Matrices Using a Spacer Arm

Preparation of Affinity-Ligand Resins by Immobilization of Dyes on Polyhydroxyl Matrices Using a Spacer Arm

Mechanism of Aβ(1−40) Fibril-Induced Fluorescence of (trans,trans)-1-Bromo-2,5-bis(4-hydroxystyryl)benzene (K114)

K114, (trans,trans)-1-bromo-2,5-bis(4-hydroxystyryl)benzene, is a fluorescent Congo Red analogue that binds tightly to amyloid fibrils, but not the monomeric proteins, with a concomitant enhancement in fluorescence. The mechanism for the low aqueous fluorescence and the subsequent enhancement by A beta(1-40) fibrils was investigated by fluorescence spectroscopy and binding analysis. K114's unusually low buffer fluorescence is due to self-quenching in sedimentable aggregates or micelles which upon interacting with amyloid fibrils undergo an enhancement in fluorescence intensity and shifts in the excitation and emission spectra. These spectral changes are suggestive of a stabilization of the phenolate anion, perhaps by hydrogen bonding, rather than an increase in the microenvironment dielectric constant or dye immobilization. 1,4-Bis(4-aminophenylethenyl)-2-methoxybenzene, which lacks the phenol moiety, and X-34, which contains a stabilized phenol (pK approximately 13.4), do not display the phenolate anion fluorescence in the presence of fibrils. The apparent affinity of K114 for fibril binding is 20-30 nM with a stoichiometry of 2.2 mol of K114/mol of A beta(1-40) monomer. Competition studies indicate that K114 and Congo Red share a site, but K114 does not bind to sites on A beta(1-40) fibrils for neutral benzothiazole (BTA-1), cationic thioflavin T, or the hydrophobic (S)-naproxen and (R)-ibuprofen molecules. Comparison of benzothiazole binding stoichiometry which has been suggested to reflect disease-relevant amyloid structures to that of Congo Red analogues which reflect total fibril content may be useful in defining biologically pertinent conformational forms of amyloid.

Immobilisation and assessment of aniline dyes for non-fluorescent pH sensing applications

The attachment of two aniline-based chromophores, Disperse Black 3 and Pararosaniline, to beaded controlled pore glass (CPG) and their testing as fibre optic based pH sensors is described. Synthetic methods for their attachment at specified loadings to CPG were developed. The Disperse Black 3 sensor displayed a rapid response time and a dynamic range between pH 1.0 and 2.5, while the Pararosaniline-bearing sensor gave an extremely slow response time but a large sensing range from pH 1 to 11.

Bilirubin removal from human plasma by Cibacron Blue F3GA using immobilized microporous affinity membranous capillary method

A novel affinity sorbent system for direct bilirubin removal from human plasma was developed. These new adsorbents comprise Cibacron Blue F3GA as the specific ligand, and microporous membranous poly(tetrafluoroethylene) capillary (modified by coating with a hydrophilic layer of poly(vinyl alcohol) after activation) as the carrier matrix. The affinity adsorbents carrying 126.5 μmol Cibacron Blue F3GA/g polymer was then used to remove bilirubin in a flow-injection system. Non-specific adsorption on the poly(vinyl alcohol) coated capillary remains low, and higher affinity adsorption capacity, of up to 76.2 mg/g polymer was obtained after dye immobilization. The bilirubin adsorption capacity of the affinity capillary decreased with increase in the recirculation rate of plasma. The adsorption capacity increased with increase the temperature while decreased with increase the ionic strength. The maximum adsorption was only observed in neutral solution (pH 6–7). The adsorption isotherm fitted the Langmuir model well. These new adsorbents have higher velocity of mass transfer, better adsorption capacity, less fouling, longer service life and good reusability. The results of blood tests suggested the dye affinity capillary has good blood compatibility.

Direct immobilization of fluorescent dyes onto ferrite nanoparticles during their synthesis from aqueous solution

FITC-avidin, a fluorescent substance, was successfully immobilized onto the surfaces of nanoparticles of ferrite of a mixture between Fe3O4 and γ-Fe2O3, during the synthesis of the nanoparticles an aqueous solution from containing Fe2+, Fe3+, and FITC-avidin. The particles were spherical in shape and ∼10 nm in size. The process was performed in open air, on near neutral conditions of pH 7–9, and at ∼4 °C. Utilizing the fluorescent magnetic particles, we successfully observed magnetic patterns (track pitch 187.5 μm) written on a floppy disk.

Immobilization of residual dyes onto ion-exchanger cellulosic materials

This article reports on the preparation of cationized cotton fiber by treating alkali cellulose cotton fibers with epoxy propyltrimethylammonium chloride (EPTMAC) in a nonaqueous medium and its use as support for the immobilization of pollutant dyes. Evidence of attaching quaternary ammonium groups onto cellulose is provided by IR analysis, nitrogen determination, and weight uptake. Four EPTMAC–Cotton fiber samples with different nitrogen content (0.5–1.85) are tested for the adsorption of four acid dyes (Acid Blue 25, Acid Yellow 99, Reactive Yellow 23, and Acid Blue 74). Adsorption is followed spectrometrically, the capacity of adsorption depending on the nitrogen content and on the number of anionic groups in the dye. The Langmuir and Freundlich isotherms constants are evaluated from the experimental data, but better agreement is obtained by using a composite isotherm of the general form Ye = iCe/(1 + jC), where i, j, and m are constants. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 171–183, 2000

Color and Fluorescence Imaging with t-Boc-protected Dihydroxynaphthacenedione

Abstract In recent years, generation of patterned images in polymer films has become a central focus in a variety fields of chemistry. Recently, generation of functional images by selective immobilization of organic dyes in the polymer film has been reported.1-3 Selective removal of acid labile protecting groups through photoinduced chemical transformation followed by chemisorption of organic dyes from solution into the patterned polymer film afforded µm-scale functional images.

Optical sensors for the determination of concentrated hydroxide

An optical sensor system has been developed for the determination of concentrated strong bases ([OH-] = 1-10 M). The base sensors consist of SiO2/ZrO2-organic polymer composites and doped high-pKa indicators. Films were obtained by spin-casting these composite materials on glass substrates and were used as sensor elements for the spectrometric determination of hydroxide. The hydrophilic nature of the mixed oxide SiO2/ZrO2 and its chemical stability in concentrated alkali made it attractive as support in the composites. The organic polymers in the composites either provided better mechanical stability and dye immobilization or enhanced OH- diffusion and sensor response. The composite sensors showed a relative standard deviation of less than 2%. The response time of a SiO2/ZrO2-Nafion composite (sensor 2) was short (5 s), and a small hysteresis was observed during reproducibility measurements with 1-4 M NaOH solutions. The sensors were found to be stable in 4 M NaOH during a 30-day durability test, showing a standard deviation of 3.0-4.7%. The diffusion kinetics and hysteresis performance of the sensors were also evaluated.

Synthesis of and Fluorescent Imaging with a Polymer Having t-BOC-Protected Quinizarin Moieties

The generation of patterned images in polymer films has been extensively studied and used in fundamental and applied research areas. The development of patterned color or fluorescent images, especially, is of great technological importance in the electronics industry. Recently, the generation of functional images by selective immobilization of organic dyes in the polymer film has been reported. Selective removal of acid-labile protecting groups through photoinduced chemical transformation followed by chemisorption of organic dyes from solution into the patterned polymer film has given micrometer-scale functional images. The two-step procedures described in the literature, however, have potential problems such as difficulty of dye penetration into polymer matrices and concern about longterm stability of the patterned images. To avoid these limitations, we have tried to develop a direct method of generating fluorescence images with a precursor molecule. The strategic basis for designing a precursor is that the precursor molecule is non-fluorescent and/or colorless, but becomes fluorescent and/or reveals color by photoinduced chemical changes. We have previously reported that the UV absorption maximum and fluorescence of quinizarin 1 can be readily altered and manipulated simply by blocking the intramolecular hydrogen bonds. Thus, the UV absorption maximum (479 nm) of quinizarin 1 shifts to a shorter wavelength (335 nm) on blocking the two phenols with two tert-butoxycarbonyl (t-BOC) groups. In addition, the t-BOC-protected quinizarin 2 has virtually no fluorescence, whereas quinizarin 1 is strongly fluorescent due to the quasi-aromatic structure caused by intramolecular hydrogen bonding. As a part of our continuing interest in the generation of relief and functional images with transiently protected precursor molecules in polymer films, we now report the synthesis of a novel polymer having t-BOC-protected quinizarin moieties and the generation of color and fluorescent images by photolithographic methods. To our knowledge, this is the first example of finely resolved fluorescent images with a polymer having transiently protected precursor pendants. The strategies employed for the synthesis of t-BOC-protected quinizarin monomer 7 are shown in Scheme 1. Aldol

Optochemical sensing by immobilizing fluorophore-encapsulating liposomes in sol–gel thin films

The chemical stability of optochemical sensors depends largely on the physiochemical properties of the supportive matrix of the sensor and on the method used to immobilize sensing reagents to the supportive matrix of the sensor. Leaking of physically immobilized sensing reagents from the matrix support decreases the stability of the sensor and its overall usefulness. Covalent immobilization eliminates leakage of the sensing reagent from the support but may lead to alteration of spectral properties and loss of analyte response. This paper presents a new method for physical immobilization of polar fluorescence dyes in a sensing support. The method is based on the immobilization of fluorescent dye encapsulating liposomes in a sol–gel film of micrometer thickness. The encapsulation of the dye molecules in the liposomes effectively increases the molecular dimensions of the sensing reagent, thus preventing its leakage from the matrix support. This paper describes the analytical properties of a pH sensor fabricated by immobilizing carboxyfluorescein-encapsulating liposomes in a sol–gel thin film. The sensor shows excellent stability with respect to dye leaking which in turn leads to high reproducibility and sensitivity of about 0.01 pH units. The linear dynamic range of the sensor is between pH 6 and 7.5 and its response time is at the sub-seconds time scale.

The Immobilization of Ionic and Neutral Crown Ether Dyes to Specific Anionic Polymer Membrane Used as a Chemical Sensor for the Determination of Metal Ions

ABSTRACT In the present study, a neutral crown ether dye (NCED), [4-Nitrophenyl)(4-(4,7,10,13,16-pantaoxa-1 azacyclooctadecyl)phenyl] diazen and an ionic crown ether dye (ICED), 1-Methyl-{2-[4-(4,7,10,13,16-pentaoxa-1 azacyclooctadecyl)phenyl]ethenyl}pyridinium-iodide were synthesized and immobilized on sulfonated hydrocarbon-based block copolymer ionomer to determine Ba2+ and Cu2+ ions in aqueous solution. 5.0×10−2 M ion solutions were used since the best absorbance increase was obtained with this concentration. The increases in absorbances after treating the NCED-immobilized thick polymer membranes (0.20 mm thickness) with Ba2+ and Cu2+ solutions were 0.1488 and 0.2446 in 120 minutes, respectively. The absorbance increases were 0.1664 and 0.3710 during the same time-interval with ICED-immobilized membranes. The response time decreased and absorbance values increased when thin polymer membranes (0.04 mm thickness) were used. The absorbance increases were 0.5088 and 0.8761, respectively in one minute with the ICED-immobilized thin membranes. These results are in agreement with shrinking in polymer dimensions. Dye-immobilized polymeric membranes can be used as sensors practically for both of the ions but sensitivity is higher towards Cu2+ ions.

Elucidating PVP Dye-Binding Mechanisms in Ink Jet Media

The extensive use of polyvinyl pyrrolidone (PVP) as an ink acceptor material derives from two concurrent attributes: the propensity to bind anionic dyes and the ability to rapidly absorb the liquid vehicle.1 Recognizing that polymer microstructure and morphology regulates ink permeability, we utilize a diverse array of PVP copolymers in order to systematically investigate the simultaneous impact of comonomer composition on ink penetration and dye immobilization. On the basis of the offset (dry time) protocol and corresponding optical density measurements, we elucidate the fundamental mechanisms underlying the chromatographic separation of ink jet dyes from aqueous solvents during the diffusion of picoliter ink drops into hygroscopic films of various PVP copolymers.

Dye Affinity Chromatography

Dye affinity chromatography is a protein purification procedure based on the high affinity of immobilized dyes for the binding sites on many proteins. It is a rapid, inexpensive, and versatile method that is applicable to the purification of crude cellular extracts. This unit presents protocol for the three types of dye affinity chromatography: negative chromatography, positive chromatography, and tandem chromatography. An initial protocol describes a chromatographic procedure in which a small volume of the protein mixture to be purified is applied to a series of miniature columns, each containing a different immobilized dye. Analysis of the flowthrough and bound material allows determination of the optimum dye material for larger-scale purification. An alternate procedure describes a similar initial selection procedure using centrifugation instead of chromatography. A support protocol describes a simple procedure for immobilization of free dyes.

Hydraulic radius and mesh size of gels

For materials with high porosity, the hydraulic radius (r h ) is not proportional to the characteristic dimension of the pore space. Techniques (e.g., NMR) that measure r h will give much larger “pore sizes” than techniques (e.g., thermoporometry) that measure pore entry radii. In this note, estimates of the relation between hydraulic radius and pore size of gel networks are obtained from cell models. The “constant” in the Kozeny equation, which relates permeability to r h , is strongly density-dependent at low densities. For gels it is suggested that the permeability is more directly related to the mesh size of the network than to the hydraulic radius. The mesh size is also critical for immobilization of dyes or enzymes in a gel, and r h is a misleading measure of the ability of a network to entrap a large molecule.

Optical sensor for the pH 10?13 range using a new support material

A pH-sensitive membrane has been developed consisting of a polyester support covered with a thin layer of cellulose onto which a pH-indicator is covalently immobilized. The sensor membrane is completely transparent and shows a pH-induced colour change that makes it capable of measuring pH in the 10–13 range. Its performance was studied with respect to relative signal change, reproducibility, and long-term use. The response time for 90% of the total signal change to occur was 1 min. The material has a response that is stable over hours of operation at high pHs. This is in contrast to conventional glass electrodes which tend to become unstable at high pH, but also suffer from interferences due to the so-called alkali error. Hence, this optrode sensor presents an attractive alternative for measuring the pH of highly alkaline solutions as occurring in chemical industry, scrubbers, and waste water treatment plants. The immobilization scheme is of general interest in that it allows immobilization of vinylsulfonyl dyes with a broad variety of pKa-values, thereby allowing the design of a variety of pH (and other) sensors possessing the same mechanical support.

LED-compatible fluorosensor for measurement of near-neutral pH values

We report on an optical sensor material suitable for fluorimetric measurement of pH in the 6–9 range using a new, fully LED-compatible fluorescent dye. Its base form has a strong absorption between 580 and 630 nm that matches the emission band of conventional yellow or orange light-emitting diodes. Two kinds of dye immobilization are reported. The first is based on covalent binding to a cellulosic matrix and the resulting material is intended for use in sensing membranes. The second involves physical entrapment of the dye in a sol-gel matrix which can be used for optical fiber tip coating as well as in evanescent wave type sensors. Both kinds of sensor materials are studied with respect to dynamic pH ranges, response times, sensitivity toward ion strength, and stability.