Optical and surface morphological properties of polarizing films fabricated from a chromonic dye by the photoalignment technique

The inherent chromonic lyotropic liquid crystalline properties of a dye have been manipulated to fabricate multi-axial micropolarizing thin films by means of the photoalignment technique. The dye aqueous solution is deposited on a photopatterned polymer film to result in the macroscopic alignment of the dye molecules, followed by drying at ambient temperature. The solid polarizing dye layers thus produced exhibit very a high contrast ratio and degree of polarization in the region of visible light. Addition of a small amount of surfactant to the dye solution is a prerequisite for the generation of a nematic chromonic phase and for the formation of homogeneous thin dye layers on the polymer film. The correlation between the optical and surface morphological properties of the dye layers is discussed.     

The pH stimulated reversible loading and release of a cationic dye in a layer-by-layer assembled DNA/PAH film

Through the layer-by-layer (LbL) deposition method, DNA was assembled into an ultrathin film with a cationic poly(allylamine hydrochloride) (PAH). The loading and release of a typical cationic dye, 5, 10, 15, 20-tetrakis(4-N-methylpyridyl)porphine-tetra-(p-toluenesulfonate) (TMPyP), in the DNA/PAH films were investigated. It has been found that the LbL-assembled DNA/PAH film was very stable in both acidic and alkaline solutions. Stimulated by the pH change of the dye solution, the dye can be easily loaded into or released from the DNA/PAH film. In an alkaline solution, the dye could be rapidly loaded into the DNA/PAH film at room temperature, while in an acidic solution, the dye could be rapidly released. The mechanism of such pH-stimulated loading and release in the DNA/PAH film was discussed. It was further observed that the loading and release of the dye in the DNA/PAH film was reversible upon pH change and the process could be repeated many times.     

Thermoresponsive polymersome from a double hydrophilic block copolymer

The article describes synthesis and thermally triggered self‐assembly of a Poly (ethylene oxide)‐block‐poly (N‐insopropylacrylamide) (PEO‐b‐PNIPAm) in aqueous medium. At rt, the polymer remains as unimer, however, at lower critical solution temperature (LCST) of PNIPAm (32 °C), it forms a rather large undefined aggregate which at slightly elevated temperature (～40 °C) converges to well defined polymersome structure (Critical aggregation concentration = 0.45 mg/mL) with hydrodynamic diameter of 40–50 nm. By lowering the temperature, initial swelling of the compact vesicle followed by reversible disassembly to unimer was noticed. The polymersome exhibits encapsulation ability to a hydrophilic dye Calcein which can be spontaneously released by lowering the temperature below cloud point. Likewise a hydrophobic dye namely 8‐Anilino‐1‐naphthalenesulfonic acid (ANS) can also be encapsulated and released by thermal trigger. Detail photoluminescence studies reveal ANS dye can be used as a generalized probe molecule for detecting LCST of a thermoresponsive polymer by “fluorescence on” above LCST even by cursory observation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2444–2451     

Unburned carbon as a low-cost adsorbent for treatment of methylene blue-containing wastewater

Fly ash, natural zeolite, and unburned carbon separated from fly ash have been employed as low-cost adsorbents for dye adsorption in methylene blue-containing wastewater. It is found that the unburned carbon exhibits a much higher adsorption capacity than raw fly ash and natural zeolite. The adsorption capacities of fly ash, natural zeolite, and unburned carbon for methylene blue are 2 x 10(-5), 5 x 10(-5), and 2.5 x 10(-4) mol/g, respectively. Investigation also indicates that adsorption is influenced by initial dye concentration, particle size, dye solution pH, and adsorption temperature. Adsorption on unburned carbon increases with the initial dye concentration, solution pH, and temperature, but reduces with the increasing particle size. Kinetic studies show that adsorption of methylene blue on fly ash, natural zeolite, and unburned carbon can be best described by the pseudo-second-order adsorption model and that adsorption is a two-step diffusion process. The apparent activation energies for methylene blue adsorption on unburned carbon in the first and second diffusion processes are 12.4 and 39.3 kJ/mol, respectively.     

Hemicyanine dye as a surfactant for the synthesis of bicontinuous cubic mesostructured silica

In this paper, we developed a facile way to synthesize highly ordered optically active MCM-48 at room temperature, by using mixtures of hemicyanine dye N-alkyl-2-[p-(N,N-diethylamino)-o-(alkyloxy)]pyridinium bromide (denoted as o-CnPOCm, Scheme 1) and cetyltrimethylammonium bromide (CTAB) as the structure-directing agents. The mesoporous materials were systematically characterized by powder X-ray diffraction, transmission electron microscopy, nitrogen sorption, and thermogravimetry. The resultant MCM-48 exhibits unusually high thermal stability. For example, in the case of o-C(2)POC(14), it can retain its cubic structure even under calcinations at 900 degrees C for 5 h, although the pore size is shifted to the micropore region because of shrinkage of the framework. The typical surface area and pore volume are 980 m(2)/g and 0.44 cm(3)/g, respectively, for the powder calcined under such a high temperature. This is the first report of room-temperature synthesis of MCM-48 with such good thermal stability using cationic-cationic mixed surfactant as the structure-directing agent. The fluorescence lifetimes of the as-synthesized mesostructured MCM-48 were also measured, and the result showed that the incorporated dye molecules have a 1 order of magnitude longer lifetime than that of free species in solution, showing that the hemicyanine dye molecules are well dispersed within the CTAB surfactant matrix. Furthermore, we compared eight other dye congeners (Scheme 1) to fully investigate the mesophase resulting from the dye-CTAB system. The results show that, upon addition of the dye surfactant to the starting mixtures, the mesostructured silica undergoes an intrinsic phase-transition process; however, specific dye geometry is required to obtain MCM-48 at room temperature. Those functionalities as well as the designed synthesis of this novel mesostructured MCM-48 material promise a bright future in multifunctional optical and electric nano- and microdevices (e.g., waveguides, laser, light-emitting diodes, etc.) and also shed light on the self-assembly behavior in complex colloidal system.     

Spacer-controlled aggregation and surface morphology of a selenacarbocyanine dye on gemini monolayers

The adsorption and aggregation of a selenacarbocyanine dye (3,3-disulfopropyl-9-methyl-selenacarbocyanine, SeCy) onto Langmuir monolayers of a series of gemini amphiphiles with different methylene spacers were investigated. When the monolayers of the gemini amphiphiles were spread on the dye-containing subphase, the dye could be easily adsorbed and aggregated onto the monolayers through the electrostatic and pi-pi interaction. The dye formed complexes with gemini amphiphiles and stacked as J-aggregates in all the transferred multilayers, regardless of the structure of gemini amphiphiles. However, the surface morphologies of the complex monolayers showed a significant dependence on the spacer length of the gemini amphiphiles and the temperature of the subphase. Nanorods were observed for the complex films with spacer lengths ranged from 4 to 10 methylenes. With the temperature of the subphases increased from 20 degrees C to 30 degrees C, aligned longer nanofibers were formed instead. Although both the gemini amphiphiles and the dye were achiral, strong circular dichroism (CD) signals were observed for the transferred complex films. However, the CD signals could be just opposite in different places of the transferred films, suggesting that a resolved enantiomeric micro/nanostructure coexisted in the films. On the other hand, for the complex film of the dye with the gemini amphiphile of two methylenes spacer, neither CD signal nor ordered surface morphologies were detected in any place of the film although the dye itself stilled formed J-aggregate in the film. It was suggested that regular nanoarchitectures and resolved chiral domains could be observed only when the spacer of gemini amphiphiles is comparative to the distance between the two SO3- groups in the dye.     

Living Supramolecular Polymerization of an Aza‐BODIPY Dye Controlled by a Hydrogen‐Bond‐Accepting Triazole Unit Introduced by Click Chemistry

An aza‐BODIPY dye 1 bearing two hydrophobic fan‐shaped tridodecyloxybenzamide pendants through 1,2,3‐triazole linkages was synthesized by a click reaction and characterized. ¹H NMR studies indicated that dye 1 exhibited variable conformations through intramolecular H‐bonding interaction, which is beneficial for the polymorphism of aggregation. The thermodynamic, structural, and kinetic aspect of the supramolecular polymerization of dye 1 was investigated by UV/Vis absorption spectroscopy, IR spectroscopy, AFM, TEM, and SEM. Biphasic aggregation pathways of dye 1 , leads to the formation of off‐pathway, metastable Agg. I and thermodynamically stable Agg. II with distinct H‐aggregation spectra and nanoscale morphology. The living manner of the supramolecular polymerization of dye 1 was demonstrated in seeded polymerization experiments with temperature‐modulated successive cooling–heating cycles.     

Adsorption and desorption studies of a water soluble dye, Quinoline Yellow, using waste materials

Bottom ash, a power plant waste, and de-oiled soya, an agricultural waste material, were employed for the removal and recovery of Quinoline Yellow, a water-soluble dye. Characterization of adsorbent materials was made by their infrared and differential thermal analysis curves. Along with batch adsorption studies, which involve effect of pH, adsorbate concentration, sieve size, adsorbent dosage, contact time, temperature, etc., kinetic studies and column operations were also made to remove the dye from wastewater. On the basis of kinetic studies, specific rate constants involved in the processes were calculated and first-order adsorption kinetics was observed in both the cases. The paper also incorporates Langmuir and Freundlich adsorption isotherm models, which are used to calculate thermodynamic parameters and also to suggest a plausible mechanism of the ongoing adsorption processes. Fixed bed columns were prepared for both the adsorbents and bulk removal of the dye was achieved by eluting aqueous solution of the dye and saturation factor for both columns were evaluated. Dilute NaOH solution was then percolated through the exhausted columns to recover the adsorbed dye.     

Removal of Reactive Yellow 84 from aqueous solutions by adsorption onto hydroxyapatite

The adsorption of a reactive dye, Reactive Yellow 84, from aqueous solution onto synthesized hydroxyapatite was investigated. The experiments were carried out to investigate the factors that influence the dye uptake by the adsorbent, such as the contact time under agitation, absorbent dosage, initial dye concentration, temperature and pH of dye solution. The experimental results show that the amount of dye adsorbed increases with an increase in the amount of hydroxyapatite. The maximum adsorption occurred at the pH value of 5. The equilibrium uptake was increased with an increase in the initial dye concentration in solution. The experimental isotherm data were analyzed using Langmuir isotherm equation. The maximum monolayer adsorption capacity was 50.25 mg/g. The adsorption has a low temperature dependency and was endothermic in nature with an enthalpy of adsorption of 2.17 kJ mol⁻¹.     

Polymer nanospheres formed by a microfluidic technique with Evans blue dye

In this work, the V‐shaped microfluidic junction (VMJ) device technique with gas/liquid interface was used to prepare textured polymer nanospheres from bubble bursting for drug delivery. The polymer/dye solution, N₂ gas, and a volatile liquid, perfluorohexane (PFH) were simultaneously fed using the tubes into the VMJ device. A high‐pressure injection of N₂ gas into the VMJ interacts with PFH and ethanol leading to the preparation of a microbubble system. Once bubbles are ejected from the VMJ outlet, nanospheres calve from the parent bubble. The collection temperature and the N₂ gas pressure play a key role in the mechanism by which nanospheres are formed. In addition, the volatile liquid, PFH, is described as a significant surface modifier. The influence of the N₂ gas pressure, collection temperature, and the volatile liquid flow rates on nanospheres size distribution and surface roughness were investigated using scanning electron microscopy. The results revealed that the N₂ gas pressure and collection temperature are crucial in tailoring the size distribution of the nanospheres and that the nanospheres textured with PFH had significantly rougher surface. Nanospheres coated with Evans blue dye were prepared, and those collected at high temperature exhibited a very different dye release profile compared with those collected at lower temperatures. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluorescence detection of single-nucleotide polymorphisms with two simple and low cost methods: a double-DNA-probe method and a bulge form method

Two 10-mer DNA probes, or one 20-mer DNA probe, respectively, hybridize with a 21-mer target DNA to form a vacancy or bulge opposite the target nucleotide. The former double-DNA-probe method and the latter bulge form method are applicable to the detection of single-nucleotide polymorphisms (SNPs). A small fluorescent dye enters into the vacancy or bulge and binds with a target nucleotide via a hydrogen bonding interaction, which causes fluorescence quenching. The interaction between fluorescent dye and the target nucleotide is confirmed by measuring the melting temperature and fluorescence spectra. The fluorescent dye, ADMND (2-amino-5,7-dimethyl-1,8-naphthyridine), is found to selectively bind with C over A or G. The methods proposed here are economic, convenient, and effective for the fluorescence detection of SNPs. Finally, the double-DNA-probe method and bulge form method are successfully applied to the detection of C/G and C/A mutations in the estrogen receptor 2 gene and progesterone receptor gene using ADMND.     

Determination of Violet Covasol as a cosmetic dye in water samples by a CPE-Scanometry method

The trace amounts of Violet Covasol as a cosmetic dye was determined by an efficient cloud point extraction-Scanometry(CPE-Scanometry) method. This method has many advantages such as novelty,facility, high speed, sensitivity, low cost and safety. The method is based on the CPE of an analyte from an aqueous solution, diluting the extracted surfactant-rich phase with ethanol, transferring to Plexiglas~cell and scanning of the cells containing the analyte solution with a scanner and measuring the RGB parameters with software written in visual basic(VB 6) media. Parameters impacting the extraction efficiency such as p H of the system, the concentration of surfactant, equilibration temperature and time were optimized. Detection limit(DL), relative standard deviation(RSD) and linear range for the proposed method are 0.026, 0.71 and 0.16–6.6 μg m L ~(-1)respectively. The method was successfully applied for the determination of Violet Covasol dye in several water samples, including a water sample containing the dye as a tracer(to investigate subsurface water movement).     

Multiplasmid DNA in agarose gel electrophoresis: Suitable dye and temperature is essential for prominent profiles

Nucleic acids dye Goldview is widely used in agarose gel electrophoresis (AGE). However, in this study, a sample of multiplasmid DNA (multi-pDNA) stained with Goldview analyzed by AGE showed its instability at low temperature. Three types of DNA samples were analyzed, including linear DNA (ladder), single-plasmid DNA (single-pDNA), and multi-pDNA, electrophoretic conditions were optimized by adjusting the dye, the buffer, and the temperature (1–50°C). The results showed that the light intensity of Gelred is 2.2-times higher than that of Goldview in staining multi-pDNA. Compared with the single-pDNA and the linear DNA, the multi-pDNA stained with Goldview was greatly affected by temperature. This short communication indicated that Gelred is a highly applicable dye for analyzing multiplasmid samples. The degree and the way of binding of Goldview to multi-pDNA are greatly affected by temperature.     

Effect of Temperature on the Binding and Distribution Characteristics of Thionine in Sodium Dodecylsulfate Micelles

The interaction between thionine (a cationic thiazine dye) and anionic surfactant sodium dodecylsulfate in aqueous solution at different temperatures has been studied spectrophotometrically. The absorption spectra were used to quantify the dye/surfactant binding constants and surfactant/water partition coefficients of the dye by applying mathematical models that consider partitioning of the dye between the micellar and aqueous pseudo-phases. The Benesi-Hildebrand equation was applied to calculate the binding constants of thionine to sodium dodecylsulfate micelles over a temperature range of 293 to 333 K. To evaluate the thermodynamic aspects of the interaction of thionine with sodium dodecylsulfate micelles, Gibbs energy, enthalpy and entropy changes were determined. The effect of temperature on the critical micelle concentration of sodium dodecylsulfate in the presence of thionine was also studied and discussed. The binding affinity of thionine to the sodium dodecylsulfate micelles significantly decreased with increasing temperature because of the thermal agitation.     

Noncontact temperature measurement in microliter-sized volumes using fluorescent-labeled DNA oligomers

A new method of noncontact temperature measurement in microliter-sized volumes is demonstrated, based on the temperature sensitivity of the fluorescence lifetime of rhodamine-G when it is attached to a DNA oligomer. As temperature changes, the spacing between the fluorescent dye and a designed sequence of DNA bases is modulated by conformation changes of the DNA chain, and as a result the ability of dye molecules to fluoresce is also modulated according to differential quenching by bases on the DNA. In the system that we studied, the temperature sensitivity of the fluorescence lifetime was 36-42 ps/ degrees C depending on specific solution conditions. Although this strategy of temperature measurement is demonstrated using a specific sequence of DNA, it can also be generalized to a dye attached to any other intrinsic quencher of fluorescence whose conformation changes with temperature.     

Photocatalytic degradation of an azo reactive dye,Reactive Yellow 84, in water using an industrial titanium dioxide coated media

The photocatalytic degradation of an azo reactive dye, Reactive Yellow 84 (RY84), in aqueous solutions using industrial titanium dioxide coated non-woven paper was studied. The experiments were carried out to investigate the factors that influence the dye photocatalytic degradation, such as adsorption, initial concentration of dye, temperature, and solution pH. The experimental results show that adsorption is an important parameter controlling the apparent kinetics constant of degradation. The photocatalytic degradation rate was favored by a high concentration of solution in respect to Langmuir–Hinshelwood model. The degradation was enhanced by the temperature and was favored in acidic pH range.     

Role reversal in a supramolecular assembly: a chiral cyanine dye controls the helicity of a peptide-nucleic acid duplex

A new dicarbocyanine dye bearing branched, chiral N-alkyl substituents was synthesized and its ability to form helical aggregates on peptide nucleic acid (PNA) double-helical templates was studied. The dye aggregates less effectively than an analogous dye bearing linear, achiral substituents, presumably due to steric problems with packing the branched substituents compared with the linear substituents. When the PNA duplex has a left-handed helicity, addition of the achiral dye leads to formation of a left-handed dye aggregate. However, when the chiral dye aggregates in the presence of this duplex, a right-handed structure is formed, suggesting that the dye alters the helicity of the underlying template. When a racemic PNA duplex (i.e., equal amounts of right- and left-handed helices) is used, no chirality is observed for the dye aggregate formed by the achiral dye but a right-handed helical aggregate is once again formed by the chiral dye. These results indicate that chirality is transferred from the dye to the PNA, as opposed to other examples of polymer-templated dye aggregation where chirality is transferred from the template to the dye.     

Adsorption of Remazol Brilliant Blue R on activated carbon prepared from a pine cone

In this work the activated pine cone was investigated as adsorbent to remove Remazol Brilliant Blue R from aqueous solution. The effects of various experimental parameters such as initial dye concentration, contact time, temperature, adsorbent dose and pH were examined. The adsorption of Remazol Brilliant Blue R from aqueous solution was increased with the increase in initial dye concentration, contact time, temperature, adsorbent dose but decreased with the increase in the pH. The results in this study indicated that the activated pine cone was an attractive candidate for removing Remazol Brilliant Blue R.     

电沉积法制备固态染料敏化太阳能电池

本文采用一步电化学沉积的方法在导电玻璃上先后沉积了ZnO/染料复合薄膜以及CuSCN薄层,实现仅以电沉积法制备结构为ZnO/染料/CuSCN的固态染料敏化太阳能电池,电池的光电转换效率达到0.1%.在电沉积CuSCN前,脱附电沉积制备的ZnO/染料复合薄膜中的染料以形成多孔ZnO薄膜,然后通过染料再吸附得到染料敏化ZnO纳晶多孔薄膜.在电沉积过程中,ZnO和CuSCN的晶体尺寸、晶体取向和膜层形貌都可以进行比较精准的控制.探讨了影响沉积薄膜形貌和光电转换效率的因素,如旋转圆盘电极的旋转速度、电沉积温度以及染料敏化剂的选择.本文报道的低温电沉积制备全固态太阳能电池的方法为制备柔性染料敏化太阳能电池提供了一种新的思路.     

Photodegradation of a textile dye catalyzed by sol–gel derived nanocrystalline TiO2 via ultrasonic irradiation

Nanocrstalline pure anatase titania were prepared by sol–gel process at room temperature followed by ultrasonication (Ti–US). The photocatalytic activity of Ti–US has been evaluated by the degradation of textile dye, Methylene Blue in presence and absence of common inorganic salts (NO₃⁻, C₂O₄²⁻, SO₄²⁻, citrate). It was observed that, in presence of anions, the degradation of the dye increases significantly. The influence of the presence of H₂O₂ on the degradation rate was studied. The dependence of photodegradation of the dye rates on various parameters such as dye concentration, photocatalyst concentration and pH were also investigated. The photodegradation rate follows first order kinetics. H₂O₂ and UV light have a negligible effect in absence of Ti–US catalyst. The relative photonic efficiency of the system is reported using phenol as a standard organic compound.