Amphiphilic ESIPT benzoxazole derivatives as prospective fluorescent membrane probes

Fluorescent amphiphilic benzoxazole derivatives were synthesized and used to produce photoactive phosphatidylcholine (PC) liposomes by reserve-phase evaporation. The dyes absorbed in the UV region and were fluorescent in the blue-green region (determined by solvent polarity). The alkyl chain length seemed to play a fundamental role in the photophysics of the benzoxazole fluorophore in reverse liposomes, and despite the same ESIPT core and phospholipid building block, each amphiphilic dye had a particular emission profile related to the dye location in the liposome. The fluorescence emission spectra from dye 5 showed that its fluorophore experienced a polar environment, due to the single normal emission, while dyes 6–7 had (in part) a normal emission, and the main fluorescent band ascribed to the ESIPT emission indicated a more hydrophobic environment. Despite the complex fluorescent profiles, the benzoxazole derivatives could be successfully introduced into the reverse liposome structure due to the interaction between the alkyl chain and PC bilayer.     

Dyeing of PA 6.6 fibers

Dyeing fibers at low temperatures has many advantages such as savings in energy and avoiding alterations to the physical properties of the fibers being dyed or other fibers also present in blends. The problem of low temperature dyeing in synthetic fibers is that it difficults the dye diffusion into the fiber. In the case of polyamide 6.6 microfibers, by using benzyl alcohol as an auxiliary dyeing, it was shown that good diffusion was obtained for the dye exhaustion with metal complex dyes at temperatures more than 30°C below the normal dyeing temperature for the dye exhaustion with metal complex dyes. Using thermal analysis methods these results were shown to be caused by the lowering of the T _g of the fiber when in the presence of benzyl alcohol. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chemical recycling of PET waste into hydrophobic textile dyestuffs

The paper aims at effective chemical recycling of poly(ethylene terephthalate) (PET) fiber waste into useful products, such as hydrophobic disperse dyes for synthetic textiles. For this, PET fiber waste was glycolytically depolymerized using excess of ethylene glycol in the presence of sodium sulfate as catalyst. The product, pure bis(2-hydroxyethylene terephthalate) (BHET) was obtained with >60% yield by successive recrystallization. In order to synthesize hydrophobic disperse dyes, applicable to synthetic textile fibers, BHET was converted to bis(2-chloroethylene terephthalate), reacted with the p-nitro benzoic acid, reduced and then reacted with bromine and potassium thiocyanate to get benzothiazole derivative. Coupling with N,N-diethylaniline produced a bright yellow disperse dye (Dye A). Similarly, coupling of p-amino benzoic ester with N,N-diethylaniline led to an orange colored disperse dye (Dye B). These dyes were applied onto polyester fabric by conventional method. Results in terms of depth of dyeing, evenness and the performance characteristics were found to be promising.     

Synthesis,characterization, and dyeing performance of some azo thienopyridine and thienopyrimidine dyes based on wool and nylon

A string of novel heterocyclic mono azo dyes were synthesized and their utilization in dyeing different fabrics as wool and nylon were discussed. Thienopyridine azo dyes 4 and 6 were prepared by reaction of chloro acetamidederivative 2 with diamino compounds to yield 3 and 5 , followed by reaction with NaNO₂/HCl and coupling with nucleophilic reagent. One-pot reaction of chloro acetamide 2 with ammonium thiocyanat in solvent ethanol gave the unexpected thienopyrimidine derivative 7 , which contain two active sites, the former is primary amine that was able to form diazonium salt that coupled with N,N-dimethylaniline, resorcinol, and/or self-coupling to afford the azo dyes 8-10 , and the latter is active methylene group that underwent coupling with different diazonium salts to give the azo thienopyrimidine derivative dye 11-15 . The dyeing performance of these azo dyes had been investigated in terms of their dyeing behavior and fastness properties on different fabrics. Results showed that the color strength (K/S) values, as well as, washing, rubbing, and resistance to acid, alkali and light showed high efficiency of these heterocyclic mono azo dyes to dye wool rather than nylon fibers.     

LIPOSOME FUSION AND LIPID EXCHANGE ON ULTRAVIOLET IRRADIATION OF LIPOSOMES CONTAINING A PHOTOCHROMIC PHOSPHOLIPID

Abstract—
A photochromic phospholipid, 1,2-bis[4-(4- n -butylphenylazo)phenylbutyroyl]phosphatidyl-choline (Bis-Azo PC) has been incorporated into liposomes of gel- and liquid-crystalline-phase phospholipids. Liposomes of gel-phase phospholipid are stable in the presence of the trans photostationary state Bis-Az.o PC and can encapsulate fluorescent marker dye. On photoisomerization to the cis photostationary state, trapped marker is rapidly released. Liposomes containing Bis-Azo PC can rapidly fuse together after UV isomerization, this process continuing in the dark. Exposure to white light causes reversion of Bis-Azo PC to the trans form and halts dye leakage and vesicle fusion. Both unilamellar and multilamellar liposomes are able to fuse together on UV exposure. On UV photolysis, liposomes containing Bis-Azo PC do not fuse with a large excess of unlabeled liposomes, but transfer of Bis-Azo PC can be demonstrated spectrophotometrically. Vesicles of pure gel-phase lipid containing trapped marker dye but initially no Bis-Azo PC become leaky as a result of this lipid transfer. Liposomes composed of liquid-crystalline-phase phosphatidylcholine-containing Bis-Azo PC neither leak trapped marker nor fuse together on photolysis, nor do liquid-crystalline-phase liposomes fuse with gel-phase liposomes under these conditions. These results are discussed together with some possible applications of liposome photodestabilization.     

Application of liposomes in the textile industry

The results of the research of the role of liposomes in bleaching, dyeing, and finishing of wool and cotton, as well as sorption of dyes are discussed.     

Active uptake of drugs into photosensitive liposomes and rapid release on UV photolysis

Liposomes containing high concentrations of the anticancer drug doxorubicin, prepared by active-loading techniques, have been intensively investigated as potential agents for chemotherapy. The present study investigates the possibility of active uptake and photoinduced release of such solutes from liposomes incorporating a photoisomerizable lipid. The active loading of acridine orange and doxorubicin was investigated using liposomes containing entrapped ammonium sulfate. The liposomes were prepared with dipalmitoyl-L-alpha-phosphatidyl choline (DPPC) and a photochromic lipid, (1,2-(4'-n-butylphenyl)azo-4'-(gamma-phenylbutyroyl))-glycero-3- phosphocholine (Bis-Azo PC), which isomerizes on exposure to near-UV light with resulting changes in membrane permeability to solutes. The rate of loading of the vesicles below the phase transition temperature of DPPC was investigated as a function of Bis-Azo PC and cholesterol concentrations in the liposome. The rate of doxorubicin uptake was found to be greatly decreased in the presence of cholesterol, while below 30 degrees C the rate of acridine orange uptake was increased in the presence of cholesterol. On exposure to a single UV laser pulse, actively loaded acridine orange was rapidly released from liposomes containing Bis-Azo PC at a rate similar to that found for the indicator dye calcein. However while cholesterol had previously been shown to greatly enhance the rate of photo-induced calcein leakage, it had no significant effect on the rate of acridine orange release. After active loading into DPPC vesicles containing Bis-Azo PC, doxorubicin was also released after exposure to a single laser pulse, but at a rate slower than for acridine orange and calcein. The difference in behavior between these systems is ascribed to the interactions of acridine orange and doxorubicin with the liposome bilayer. Photoinduced release of pharmacologically active materials from sensitized liposomes might provide a useful adjunct or alternative to conventional photodynamic therapy.     

Application of Functionalized DVB-co-GMA Polymeric Microspheres in the Enhanced Sorption Process of Hazardous Dyes from Dyeing Baths

Intensive development of many industries, including textile, paper, plastic or food, generate huge amounts of wastewaters containing not only toxic dyes but also harmful auxiliaries such as salts, acid, bases, surfactants, oxidants, heavy metal ions. The search for effective pollutant adsorbents is a huge challenge for scientists. Synthesis of divinylbenzene copolymer with glycidyl methacrylate functionalized with triethylenetetramine (DVB-co-GMA-TETA) resin was performed and the obtained microspheres were evaluated as a potential adsorbent for acid dye removal from dyeing effluents. The sorption capacities were equal to 142.4 mg/g for C.I. Acid Green 16 (AG16), 172 mg/g for C.I. Acid Violet 1 (AV1) and 216.3 mg/g for C.I. Acid Red 18 (AR18). Non-linear fitting of the Freundlich isotherm to experimental data was confirmed rather than the Langmuir, Temkin and Dubinin-Radushkevich. The kinetic studies revealed that intraparticle diffusion is the rate-limiting step during dye adsorption. Auxiliaries such as Na₂SO₄ (5–25 g/L), CH₃COOH (0.25–1.5 g/L) and anionic surfactant (0.1–0.5 g/L) present in the dyeing baths enhance the dye adsorption by the resin in most cases. Regeneration of DVB-co-GMA-TETA is possible using 1 M NaCl-50% v/v CH₃OH.     

Steric and electrostatic effects in dye-cellulose interactions by the MTD and CoMFA approaches

This paper presents the application of the MTD (minimal steric difference) analysis and CoMFA (comparative molecular field analysis) to series of anthraquinone vat, mono and disazo and disperses dyes with known affinities for cellulose fiber. A comparison of the results demonstrates that these methods usually agree with the prediction of structural features favorable for dyeing. A series of n = 49 anthraquinone vat dyes was studied by MTD with r2 between 0.903 and 0.941 and r2CV values in the range of 0.827-0.878. For CoMFA, r2 = 0.992, r2CV = 0.841 were obtained; the CoMFA field is in rather good agreement with vertex attributions, by MTD for attractive and repulsive vertices. Anionic disazo dyes were studied by the CoMFA method (n = 21, r2 = 0.999, r2CV = 0.703). Monoazo dyes (several series) were studied by CoMFA and MTD. The effect of lipophilicity on dye fiber affinity was, also, studied for these dyes. Disperse dye adsorption was analyzed by MTD and CoMFA (n = 27, r2 = 0.925, r2CV = 0.776). Conclusions refer to the effect of structural features of dye molecules upon adsorption on cellulose fibers.     

The use of low-temperature plasmas in wool finishing

Processes that occur in wool fiber under the action of a glow-discharge plasma were considered. The kinetics of plasma etching, the amino acid compositions of whole fiber and separated cuticle elements, the surface of fiber (using scanning electron microscopy and attenuated total multiple internal reflection IR spectroscopy), as well as the electrosurface, friction, and other properties, were studied. These studies demonstrated that undergoing degradation and modification were primarily the fiber cuticle and its proteins and, particularly, lipids. Important reaction paths were processes involving the transformations of free radicals. Cystine, peptide, alanine, and glycine radicals were identified on the basis of EPR spectra. Plasma treatment enhanced the wettability of wool and the diffusion of dyes into fibers upon dyeing and printing and decreased the felting ability. This treatment did not impair the physicomechanical, heat-insulation, and thermal properties of wool. However, the resulting changes somewhat decreased the hydrophilicity of wool after plasma treatment.     

Surface enhanced Raman scattering detection of water-soluble derivatives of fullerene C<Subscript>60</Subscript> and their covalent conjugates with dyes in biological model systems

The potential of surface enhanced Raman spectroscopy (SERS) for the detection of water-soluble fullerene derivatives and their covalent conjugates with xanthene dyes was investigated in model biological liposome membranes and in the albumin protein structure. It was shown that in liposomes and in albumin, fullerene derivatives and their covalent conjugates with dyes show characteristic SERS spectra, which allows detection of water-soluble fullerene derivatives in phosphatidylcholine liposomes at the lipid/fullerene derivative ratio of 100 as well as fullerene–dye conjugates in liposomes and albumin.     

Chemical cationization of cotton fabric for improved dye uptake

Cotton fabric is usually dyed with reactive dyes. During the dyeing process, a large amount of salt is required to achieve higher exhaustion of the dye from the dyebath onto the fiber. Dyeing of cotton with reactive dyes has a substantial environmental impact due to the discharge of a large volume of highly colored and saline effluents. Chemical cationization allows cotton fibers to be dyed without salt by chemically modifying cellulosic macromolecules to introduce positively charged sites. In this study, cotton fabric was cationized using (3-chloro-2-hydroxylpropyl) trimethyl-ammonium chloride (CHPTAC). Dye uptake was assessed using two reactive dyes, CI Reactive Blue 235 and CI Reactive Blue 19. Dye exhaustion kinetics were determined using a Datacolor-HueMetrix Monitor system. Analysis of variance demonstrated significant effects of CHPTAC concentration and exhaustion time on the percent exhaustion. Color strength at the end of the dyeing cycle was significantly higher for cationized fabrics compared to the control fabric. This work shows that treatment of cotton with CHPTAC enhanced dye uptake properties due to the introduction of cationic sites and resulted in superior dyeing without the addition of salt.     

Steric and electrostatic effects in dye-cellulose interactions by the MTD and CoMFA approaches

This paper presents the application of the MTD (minimal steric difference) analysis and CoMFA (comparative molecular field analysis) to series of anthraquinone vat, mono and disazo and disperses dyes with known affinities for cellulose fiber. A comparison of the results demonstrates that these methods usually agree with the prediction of structural features favorable for dyeing. A series of n =49 anthraquinone vat dyes was studied by MTD with r 2 between 0.903 and 0.941 and r CV 2 values in the range of 0.827-0.878. For CoMFA, r 2 =0.992, r CV 2 =0.841 were obtained; the CoMFA field is in rather good agreement with vertex attributions, by MTD for attractive and repulsive vertices. Anionic disazo dyes were studied by the CoMFA method ( n =21, r 2 =0.999, r CV 2 =0.703). Monoazo dyes (several series) were studied by CoMFA and MTD. The effect of lipophilicity on dye fiber affinity was, also, studied for these dyes. Disperse dye adsorption was analyzed by MTD and CoMFA ( n =27, r 2 =0.925, r CV 2 =0.776). Conclusions refer to the effect of structural features of dye molecules upon adsorption on cellulose fibers.     

Extracting natural dyes from wool--an evaluation of extraction methods

The efficiency of eight different procedures used for the extraction of natural dyes was evaluated using contemporary wool samples dyed with cochineal, madder, woad, weld, brazilwood and logwood. Comparison was made based on the LC-DAD peak areas of the natural dye's main components which had been extracted from the wool samples. Among the tested methods, an extraction procedure with Na(2)EDTA in water/DMF (1:1, v/v) proved to be the most suitable for the extraction of the studied dyes, which presented a wide range of chemical structures. The identification of the natural dyes used in the making of an eighteenth century Arraiolos carpet was possible using the Na(2)EDTA/DMF extraction of the wool embroidery samples and an LC-DAD-MS methodology. The effectiveness of the Na(2)EDTA/DMF extraction method was particularly observed in the extraction of weld dye components. Nine flavone derivatives previously identified in weld extracts could be identified in a single historical sample, confirming the use of this natural dye in the making of Arraiolos carpets. Indigo and brazilwood were also identified in the samples, and despite the fact that these natural dyes were referred in the historical recipes of Arraiolos dyeing, it is the first time that the use of brazilwood is confirmed. Mordant analysis by ICP-MS identified the widespread use of alum in the dyeing process, but in some samples with darker hues, high amounts of iron were found instead.     

Intrinsic heterogeneity in liposome suspensions caused by the dynamic spontaneous formation of hydrophobic active sites in lipid membranes

The spontaneous, dynamic formation of hydrophobic active sites in lipid bilayer membranes is studied and characterized. It is shown that the rates of formation and consumption of these active sites control at least two important properties of liposomes: their affinity for hydrophobic surfaces and the rate by which they spontaneously release encapsulated molecules. The adhesion and spreading of liposomes onto hydrophobic polystyrene nanoparticles and the spontaneous leakage of an encapsulated fluorescent dye were monitored for different liposome compositions employing Cryo-TEM, DLS, and fluorescence measurements. It was observed that an apparently homogeneous, monodisperse liposome suspension behaves as if composed by two different populations: a fast leaking population that presents affinity for the hydrophobic substrate employed, and a slow leaking population that does not attach immediately to it. The results reported here suggest that the proportion of liposomes in each population changes over time until a dynamic equilibrium is reached. It is shown that this phenomenon can lead to irreproducibility in, for example, spontaneous leakage experiments, as extruded liposomes leak much faster just after preparation than 24 h afterward. Our findings account for discrepancies in several experimental results reported in the literature. To our knowledge, this is the first systematic study addressing the issue of an existing intrinsic heterogeneity of liposome suspensions.     

Synthesis of an electron-rich aniline-containing dye and its dyeing behaviors on silk through a three-component Mannich-type reaction

Under the guidance of the finding that the tyrosine residues in proteins could undergo three-component Mannich-type reactions with formaldehyde and electron-rich aniline-containing compounds,which forms covalent bonding connections between the protein of interest and the aniline with high levels of selectivity under relatively mild conditions,an orange aromatic primary amine-containing acid dye AMODB was designed and readily synthesized.The molecular structure was characterized by FTIR,~1H NMR,mass spectrometry and elemental analysis.The synthesized dye and a similar control dye(C.I.Acid Yellow 11) without primary amine groups were applied to dye silk fabric by three dyeing processes:Mannich-type dyeing(with and without the addition of formaldehyde) and acidic dyeing.Their washing and rubbing fastness properties with different dyeing methods were examined and compared.It was found that the dyed silk fabric with AMODB by the Mannich-type dyeing showed higher color depth,better anti-stripping ability to DMF and better washing fastness than those of the dyed silk fabric with C.I.Acid Yellow 11 by acidic dyeing due to the covalent bond formation between the dye chromophore of AMODB and silk fiber.In addition,mild Mannich dyeing conditions suitable for silk(AMODB at 3%owf,75:1 liquor-to-goods ratio,dyebath pH 5.5,30℃,10 h) were provided.     

Adsorption of dyes on activated carbon and graphitic thermal carbon black

The adsorption of a basic dye (Methylene Blue; MB) and an acidic dye (Acid Orange; AO) has been studied on three activated carbons (ACs; FAS, SKD, and BAU) significantly differing in their porous structures and surface concentrations of ion-exchange groups and on graphitic thermal carbon black (GTCB). The effective specific surface area of FAS, SKD, and BAU determined by dye adsorption is, respectively, 60, 50, and 40% of the BET nitrogen adsorption surface area. The MB uptake on ACs and GTCB increases with rising pH, while the AO uptake decreases. Addition of an electrolyte (0.3 M NaCl) virtually does not effect the adsorption of dyes on ACs and GTCB. It is suggested that hydrophobic interactions, and not ionic ones, are the major contributors to the adsorption of dyes on ACs.     

A rapid feedback characterization technique for polymeric hollow fiber membranes using disperse dyes

The long time lag between fiber spinning and the availability of characteristic data for process evaluation currently complicates research in hollow fiber membrane formation. This lag time is due to the down-stream processing required before traditional gas based permeation measurements can be made on the spun fiber. A rapid feedback characterization technique, based on commercially available disperse dyes, is described here for polymeric hollow fiber membrane spinning applications. This technique involves dyeing wet hollow fibers, immediately after spinning, in an aqueous dye bath. In the present work, polysulfone fibers are shown to be characterizable using this method before lengthy down-stream processing (i.e. solvent exchange, drying, and post-treatment). Dye uptake in the hollow fibers is a function of skin porosity, thereby allowing quick evaluation of permeation characteristics. Dye uptake was measured using UV-visible spectrophotometry. Examples of fibers characterized using this technique and relationships between dye uptake and post-treated permselectivity are shown and discussed.     

Study on the Influence of Nitrogen Plasma on Dyeing Properties of Rex Rabbit Fibers

The surface of rex rabbit fibers is hydrophobic in nature because of the presence of the hard cuticle on its surface, and this hydrophobicity may give rise to many problems in the dyeing and finishing processes. In order to improve its dyeability and decrease dye pollution in sewage discharge, nitrogen plasma was used to modify rabbit fibers and after that the modified fibers were dyed with the anionic dyestuffs (C.I. number 16185). The effects of nitrogen plasma on the dyeing properties and the dyeing behavior for the rex rabbit fibers were studied, the related parameters including the treatment time and discharge power were optimized. Surface morphology and roughness of rex rabbit fibers were characterized by scanning electron microscope and atomic force microscopy. XPS and FTIR-ATR were further performed to determine the surface chemical compositions of rex rabbit fibers. The physical properties of rex rabbit fibers were characterized by tensile strength tests. The results show that nitrogen plasma treatment can remove surface scales on the rex rabbit fibers and introduce more active groups such as hydroxyl (–OH), carbonyl (–C=O), and amino (–NH₂) on the surface of the fibers, which makes rex rabbit fibers have better dyeability, and effectively improves dyeing rate and dye fixation rate.     

Polyurethanes as polymerizable dyes for hydrophobic polyester fabric

The present invention is to provide a novel benzothiazole-type polymerizable dye containing a urethane bond. A series of monomeric dyes have been prepared by diazotization of various 2-aminobenzothiiazole and coupled with Resorcinol. The polymeric dyes have been prepared by polycondensation of monomeric dyes with hexamethylene diisocyanate (HMDI), and they are characterized by molecular weight, non-aqueous conductometric titration, thermogravimetry analysis, IR, visible spectroscopy, and elemental analysis. The monomeric dyes have also been characterized by elemental analysis and IR spectra. The purity of all the dyes have been checked by thin layer chromatography, and their dyeing performance on nylon and polyester was assessed. The dyeing on polyester fiber had yellow, orange and pink shades with moderate to good light and wash fastness. Polymerizations of monomeric dyes with HMDI on dyed polyester have also been carried out. Color and dyeability of the polymeric dyes have been discussed by comparing them with their corresponding monomeric dyes. The percentage dye bath exhaustion and fixation on fiber have been found to be from good to very good. The dyeing of monomeric dyes showed very good color fastness properties, and their corresponding polymeric dyes showed excellent fastness to light, washing, perspiration, solvent resistance, and sublimation.