Fluorescent Whitening Agents Research Articles

Layer-by-layer hyaluronic acid/chitosan polyelectrolyte coated mesoporous silica nanoparticles as pH-responsive nanocontainers for optical bleaching of cellulose fabrics

Polyelectrolyte multilayer (PEM) films composed of two natural polysaccharides (hyaluronic acid and chitosan) were deposited through layer-by-layer (LbL) assembly on top of biocompatible mesoporous silica nanoparticles (MSNPs). Polyelectrolyte multilayer coated mesoporous silica nanoparticles (PEM-MSNPs) were characterized by using attenuated total reflection–fourier transform infrared spectroscopy (ATR–FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherms, UV–vis and fluorescence spectrophotometer. A commercially available and industrially used optical brightener, 4,4′-distyrylbiphenyl sulfonate sodium salt (CBSX) was loaded into nanocontainers (CBSX@PEM-MSNPs) to evaluate their use for the pH-sensitive release. The controlled release of CBSX from nanocontainers in response to pH is monitored by using UV–vis and fluorescence spectrophotometer in water and the almost 100% of encapsulated CBSX is released within 2h at pH 7. The increase in both whiteness and total color change at pH 7 on a cellulose fabric demonstrates the great potential of nanocontainers as pH-sensitive whitening agents for optical bleaching of cellulose fabrics.

Ionic liquid as a mobile phase additive in high-performance liquid chromatography for the simultaneous determination of eleven fluorescent whitening agents in paper materials.

In the present study, 11 4,4'-diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents with different numbers of sulfonic acid groups were separated by using an ionic liquid as a mobile phase additive in high-performance liquid chromatography with fluorescence detection. The effects of ionic liquid concentration, pH of mobile phase B, and composition of mobile phase A on the separation of fluorescent whitening agents were systematically investigated. The ionic liquid tetrabutylammonium tetrafluoroborate is superior to tetrabutylammomnium bromide for the separation of the fluorescent whitening agents. The optimal separation conditions were an ionic liquid concentration at 8 mM and the pH of mobile phase B at 8.5 with methanol as mobile phase A. The established method exhibited low limits of detection (0.04-0.07 ng/mL) and wide linearity ranges (0.30-20ng/mL) with high linear correlation coefficients from 0.9994 to 0.9998. The optimized procedure was applied to analyze target analytes in paper samples with satisfactory results. Eleven target analytes were quantified, and the recoveries of spiked paper samples were in the range of 85-105% with the relative standard deviations from 2.1 to 5.1%. The obtained results indicated that the method was efficient for detection of 11 fluorescent whitening agents.

Skin Cancer and UV Protection

Abstract The incidence of skin cancer is increasing by epidemic proportions. Basal cell cancer remains the most common skin neoplasm, and simple excision is generally curative. On the other hand, aggressive local growth and metastasis are common features of malignant melanoma, which accounts for 75% of all deaths associated with skin cancer. The primary cause of skin cancer is long exposure to solar ultraviolet radiation (UV-R) crossed with the amount of skin pigmentation and family genetics. It is believed that in childhood and adolescence, 80% of UV-R gets absorbed while in the remaining, 20 % gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Reducing the exposure time to sunlight, using sunscreens and protective textiles are the three ways of UV protection. Most people think that all the clothing will protect them, but it does not provide full sun screening properties. Literature sources claim that only 1/3 of the spring and summer collections tested give off proper UV protection. This is very important during the summer months, when UV index is the highest. Fabric UV protection ability highly depends on large number of factors such as type of fiber, fabric surface, construction, porosity, density, moisture content, type and concentration of dyestuff, fluorescent whitening agents, UV-B protective agents (UV absorbers), as well as nanoparticles, if applied. For all of these reasons, in the present paper, the results of UV protecting ability according to AS/NZS 4399:1996 will be discussed to show that standard clothing materials are not always adequate to prevent effect of UV-R to the human skin; and to suggest the possibilities for its improvement for this purpose enhancing light conversion and scattering. Additionally, the discrepancy in UV protection was investigated in distilled water as well as Adriatic Sea water.

Print Quality Control Management for Papers Containing Optical Brightening Agents

Optical brightening agents (OBAs) or fluorescent whitening agents (FWAs) are chemicals added to paper during the papermaking process to increase the brightness of paper (chemical additives that increase the reflection of blue light (caused by ultraviolet light with a wavelength below 400nm) for the correction of a natural yellow color of paper pulp). Papers with agents for optical brightening are often represented on the market. The aim of this paper is to show that colors reproduced on paper with (Iggesund Incada Silk, 220g/m) and without (Iggesund Incada Silk T, 205g/m) agents for optical brightening, are different during the same printing conditions. Standard ISO 13655 (Spectral Measurement and Colorimetric Computation for Graphic Arts Images) defines the “M” series of illumination, which provides color management in these conditions.

The Gewald reaction in dye chemistry

This review presents the most elegant and promising set of synthetic routes for the synthesis of 2‐aminothiophenes by the Gewald reaction. This reaction has applications in several applied fields, such as pharmaceuticals/biomedicine, agrochemicals, carbohydrate conjugates, sugar cane ripeners, peptide analogues, dyestuffs, and electronic materials; however, the present review will focus on the use of Gewald chemistry in the synthesis of conventional and functional colourants. The Gewald reaction produces 2‐aminothiophene, which is a key intermediate for the diazotisation reaction and for the synthesis of azo dyes, and thus opened the door for new dye chemistry. The reaction produces electron‐withdrawing groups such as CN, COOEt, COOMe, CONH2, and COPh in the 3‐ and/or 5‐position, resulting in bathochromic shifts for the deeper colours of the dyes. The review further reveals the importance of this reaction in the synthesis of azo dyes, fluorescent dyes (coumarin dyes, styryl dyes, thieno[2,3‐d]pyrimidine dyes, bithiophene dyes), thiophene analogues of phthalocyanines, and fluorescent whitening agents.

A fluorescent method for visualization of Nosema infection in whole-mount honey bee tissues

Honey bees are critical pollinators in both agricultural and ecological settings. The Nosema species, ceranae and apis, are microsporidian parasites that are pathogenic to honey bees. While current methods for detecting Nosema infection have key merits, additional techniques with novel properties for studying the cell biology of Nosema infection are highly desirable. We demonstrate that whole-mount staining of honey bee midgut tissue with chitin-binding agent Fluorescent Brightener 28 and DNA dye Propidium Iodide allows for observation of Nosema infection in structurally intact tissue, providing a new tool for increasing our understanding of Nosema infection at the cellular and tissue level.

Synthesis of polymeric fluorescent brightener based on coumarin and its performances on paper as light stabilizer, fluorescent brightener and surface sizing agent

In this work, a novel polymeric fluorescent brightener based on coumarin (PFBC) was synthesized, using three-step synthetic route, from 7-amino-4-methylcoumarin, coumarin monomer (FBC), Acrylamide (AM) and methacrylatoethyl trimethyl ammonium chloride (DMC). The structure of PFBC was characterized by FT-IR, 1HNMR and GPC. PFBC was applied to paper fiber as light stabilizer, fluorescent brightener and surface sizing agent and its performances were evaluated by measuring the UV–vis, fluorescence, thermal stability, the cationic degree, surface strength and smoothness of paper, the brightness degree of paper and the PC value of paper. Results showed that PFBC had better solubility in water than that of FBC, by measuring the optical properties. Through the surface sizing experiment and UV aging experiment, PFBC not only enhanced the surface strength and smoothness of paper as a surface sizing agent, but also had better effect on anti-UV aging than that of FBC as light stabilizer and fluorescent brightener.

Detailed analysis of the UV‐adjustment techniques used in paper and graphic industries

AbstractMany commercial materials (papers and boards) contain optical brightening agents also known as fluorescent whitening agents. Adequate adjustment of the UV content of a measurement device (e.g., spectrophotometers) is essential for accurate color measurement. As specified in the ISO standards, the UV content is adjusted against an assigned value of an international reference transfer standard, for example, CIE whiteness (D65/10°) for the CIE illuminant D65 or ISO brightness for the C illuminant. Because of the simplicity, these approaches have gained great popularity in papermaking industry. Yet, there has been little evidence indicating how accurate the total spectral radiance factor corresponding to the single assigned value is reproduced. Hence, we present a method that quantitatively evaluates the accuracy of the UV‐adjustment technique, through comparing the total spectral radiance factors obtained from UV adjustment with the assigned ones. This method has been applied to three second‐level international reference transfer standard illuminated by three standard illuminants, D65, C, and D50. We found that the major differences between the assigned spectra and those obtained from the UV adjustments occur in the blue band where fluorescence is strong. At a few wavelengths, the differences may be up to 4–5%. Nevertheless, their color differences corresponding to the assigned spectra and those obtained from the UV adjustments are still smaller than unity (1 ΔE*) for all of the illumination conditions. Two instruments using the representative UV adjusting techniques, for example, the conventional UV‐adjusting with an adjustable (GG395) UV filter and the numerical UV‐filtering, have been studied. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 19–26, 2017

Goniometrical measurements of fluorescence quantum efficiency

Fluorescent brightening agents are widely used in various industries to enhance the appearance of materials. In order to describe the colour of a fluorescent surface, accurate measurements of fluorescence emission are needed. In this work, measurements of goniometrically resolved bispectral luminescent radiance factors are presented with improved uncertainties. In addition, a method for goniometrically determining the spectral quantum efficiencies of the fluorescent process is presented and validated. The advantage of goniometric measurements is that they avoid the need to assume a specific angular emission profile of the fluorescent sample.

Determination of three fluorescent whitening agents (FWAs) and their migration research in food contact plastic packaging containers and food simulants by UPLC-MS/MS method

A sensitive UPLC-MS/MS method was developed to determine three fluorescent whitening agents (FWAs) (FWA184, 368 and 393) in migration solutions of food contact plastic packaging containers based on the migration tests using food stimulants.

Simultaneous determination of fluorescent whitening agents (FWAs) and photoinitiators (PIs) in food packaging coated paper products by the UPLC-MS/MS method using ESI positive and negative switching modes

A sensitive ultra-high performance liquid chromatography tandem mass spectrometry method is established for the simultaneous determination of FWAs and PIs in food packaging.

Rapid Detection of Proteins on One-Dimensional Polyacrylamide Gel Electrophoresis Using an Inexpensive Fluorescent Optical Brightener

A commercial fabric fluorescent optical brightener Ranipal® (F-OB), has been successfully employed to stain proteins on native and SDS-1D-PAGE. The F-OB was purified by using a biphasic solvent system of dichloromethane and water. The Rf value (0.63) of purified and crude F-OB were comparable on TLC. The mass spectrometry of purified F-OB indicated base peak at 414 (m/z). Absorption and emission maxima of F-OB were found to be 350 nm and 430 nm, respectively. The F-OB could stain the proteins both pre- and post-electrophoretic run, on native gel. Postelectrophoretic staining was rapid and required 20 min to visualize the stained proteins. On the other hand, in SDS gels, an additional 20 min was required for the extraction of SDS before staining the proteins with F-OB. SDS was found to interfere with binding of F-OB to proteins. Varying concentrations of molecular weight markers were loaded and their fluorescent intensity was plotted against the concentration of the proteins. The r2 values ranged from 0.965 to 0.997 indicating excellent linearity. The detection for carbonic anhydrase was in the range of 8.0-800 ng. Unlike most of the dyes used for protein staining, staining with F-OB could be carried out in tank buffer (2 mg/100 mL) and was also reversible. The F-OB, perhaps would be the most cost-effective fluorescent dye to stain the proteins (US $ 0.04/25.0 g). The F-OB was found to be simple, safe, sensitive, less time consuming and economical fluorescent dye as an alternative, for staining proteins on polyacrylamide gels.

Pattern classification system for the automatic analysis of paper for recycling

The objective of this paper is the development of a pattern classification system for the automatic analysis of the composition of samples from paper for recycling. The system uses a colour video camera and dynamic scales as sensors. An overall number of 26 features of the categories weight, shape, colour, texture and amount of optical brighteners are extracted to distinguish between ten classes of paper for recycling. Five classifiers of different types are trained and tested with industrial samples. During testing a piece of paper is assigned to the class most common among the five classifiers, but the classification success rates lie under 50% for some classes and are therefore not acceptable. For this reason, the system is modified to discriminate only between six of the ten classes. For those classes, the classification success rates lie between 94% and 100% which is suitable for the analysis of samples from paper for recycling.

유아용 유기면 의류의 소비 및 안전성능 인증실태

This study surveyed the recognition and credibility of infant's organic cotton apparel and examined the current quality of children's organic cotton clothes available in the market. This study contributes to improve fabric certification programs and safety standards by understanding customer opinions and actual quality. A customer survey revealed that customers believe that organic cotton products should not include chemicals such as pesticides, fluorescent whitening agents and chemical colors; in addition, customers have high expectations for safety as well as worries about the products' validity. Children's underwear was the most purchased item category among organic cotton products. Current organic cotton certification programs are voluntary with multiple organizations that provide various certification standards. A total of 34.2% of children's organic cotton clothes sold at online and offline stores were not certified, and 10.5% had invalid certification information. This may substantially lower the credibility of organic cotton products and requires immediate change. Examination of organic cotton products showed that products do not meet customer expectations for quality and safety: 3 out of 8 products used accessories (buttons and wappens) that include harmful chemicals such as lead, phthalate and formaldehyde, 6 products used fluorescent whitening agents, and 4 products used other fabrics such as rayon, polyurethane and polyester. GOTS mark is the most recognized organic certification, but it still allows the usage of fluorescent whitening agents, which indicates a gap between customer opinions and actual certification standards. Managing national-level mandatory certification programs like food and setting quality standards that meets customer expectations are required to enhance the credibility of organic cotton products.

Adsorption Analysis of Fluorescent Whitening Agent on Cellulosic Fibers by Zeta Potential Measurement

ABSTRACT Many researchers have proposed analytical methods to measure the adsorption of di-sulpho fluorescent whitening agents (D-FWAs), but practical methods for D-FWA utilization in an actual paper mill have not been established. In particular, the D-FWA adsorption behavior must be monitored in paper mills to ensure the effective use of D-FWAs. This study used the zeta-potential of pulps as an indicator of the adsorption behavior of a D-FWA. We identified the relationship between the actual adsorption of the D-FWA and the zeta-potential of the pulps as a function of D-FWA addition. zeta-potential measurements were then used to analyze the D-FWA adsorption behavior under different conditions of pulp type, conductivity, and pH. The actual adsorption of a D-FWA was proportional to the Δzeta-potential of the pulps (i.e., the difference between the zeta-potential of a pulp containing no D-FWA and one containing the D-FWA). The Δzeta-potential of the pulps was therefore adopted for ad-sorption analysis. A higher adsorption of the D-FWA was observed onto Hw-BKP than onto Sw-BKP because of the shorter fiber length and higher fines content of Hw-BKP. A high conductivity and an acidic pH decreased the D-FWA adsorption because of direct effects of high ion concentrations and low pH on the D-FWA solubility. Therefore, a D-FWA must be added to Hw-BKP under low conductivity conditions and at neutral or alkaline pH to optimize the D-FWA adsorption.

Synthesis and Application of a Multifunctional Fluorescent Polymer Based on Coumarin

A multifunctional fluorescent polymer based on coumarin (MFPC) was synthesized using a four-step synthetic route. To obtain the target compound, 7-amino-4-methylcoumarin, coumarin fluorescent monomer (CFM), and ultraviolet absorber monomer (UVAM) were prepared. By the reaction of CFM, UVAM, trimethyl-2-methacroyloxyethylammonium chloride (DMC), and acrylamide (AM) as a linker, a new multifunctional fluorescent polymer was synthesized. The structure of the MFPC was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H-NMR) spectroscopies. The optical properties of MFPC were measured by ultraviolet-visible (UV-vis) and fluorescence spectroscopies, in aqueous solution. The integration effect between MFPC and paper was tested by scanning electron microscopy. The application performance of MFPC on paper was evaluated by measuring the surface strength, smoothness, and whiteness using the printability tester and the UV accelerated aging test. Results indicated that the MFPC had good solubility in water. It also exhibited a positive effect on the light stability and surface strength of paper as a light stabilizer, fluorescent brightener, and surface sizing agent.

Encapsulation and pH-responsive release of an optical brightener (CBUS) from chitosan microcontainers for optical bleaching of cellulosic fabrics

Encapsulation of an industrially used optical brightener, namely disodium 4,4′-bis[(4-anilino-6-morpholino-1,3,5-triazin-2-yl)amino]-stilbene-2,2′-disulfonate (CBUS), with a biodegradable natural chitosan biopolymer is studied. CBUS-loaded chitosan microcontainers were produced by the simple coacervation/precipitation method. Their morphologies in dry state were investigated by scanning electron microscopy. Controlled release of CBUS from the microcontainers in response to pH was monitored by using ultraviolet–visible (UV–Vis) and fluorescence spectrophotometry in water, with almost 100 % of the encapsulated CBUS being released within the first 90 min at pH 2. Fluorescent microscopy measurements indicated that such encapsulation of CBUS with natural chitosan biopolymer is an effective way to protect and improve light stability. The increase in both whiteness and total color change at pH 2 for the cellulosic fabric demonstrates the great potential of CBUS-loaded chitosan microcontainers as smart pH-responsive whitening agents for optical bleaching of cellulosic fabrics.

An ultrasonic humidification fluorescent tracing method for detecting unsaturated atmospheric water absorption by the aerial parts of desert plants

Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and utilize saturated atmospheric water such as fog, dew and condensed water. So far, however, there have been few studies on the aerial parts of desert plants in their absorption of unsaturated water from the atmosphere. This study presents an ultrasonic humidification fluorescent tracing method of detecting unsaturated atmospheric water absorption by the aerial parts of desert plants. We constructed an organic glass room based on the sizes of field plants. Then, the aboveground parts of the plants were humidified in the sealed glasshouse using an ultrasonic humidifier containing fluorescent reagents. The humidity and wetting time were controlled by turning on or off the humidifier according to the reading of a thermo-hygrometer suspended in the glasshouse. Fluorescence microscopy was employed to observe these plant samples. This method can generate unsaturated atmospheric water vapor and incorporate other fluorescent reagents or water-soluble chemical reagents for gasified humidification. In addition, it can identify plant parts that absorb unsaturated atmospheric water from the air, detect water absorption sites on the surface of leaves or tender stems, and determine the ability of tissues or microstructure of aerial parts to absorb water. This method provides a direct visual evidence for the inspection of leaf or tender stem microstructure in response to unsaturated atmospheric water absorption. Moreover, this method shows that aqueous pores in the cuticles of leaves or tender stems of desert plants are large enough to allow the passage of ionic fluorescent brightener with a molecular weight of up to 917 g/mol. Thus, this paper provides an important approach that explores the mechanism by which desert plants utilize unsaturated atmospheric water.

A simple and versatile cell wall staining protocol to study plant reproduction.

Key messageThe optical brightener SCRI Renaissance 2200 can be used as versatile dye to study various aspects of plant reproduction by confocal laser scanning microscopy. The study of sexual reproduction of plants has traditionally relied on light microscopy in combination with a variety of staining methods. Transgenic lines that label specific cell or tissue types with fluorescent proteins in combination with confocal laser scanning microscopy were an important development to visualize gametophyte development, the fertilization process, and to follow cell differentiation in the early embryo. Staining the cell perimeter to identify surrounding tissue is often a necessary prerequisite to put the fluorescent signal in the right context. Here, we present SCRI Renaissance 2200 (SR2200) as a versatile dye to study various aspects of plant reproduction ranging from pollen tube growth, guidance and reception to the early patterning process in the developing embryo of Arabidopsis thaliana. Furthermore, we demonstrate that SR2200 can be combined with a wide variety of fluorescent proteins. If spectral information can be recorded, even double labeling with dyes that have very similar emission spectra such as 4′,6-diamidin-2-phenylindol (DAPI) is possible. The presented staining method can be a single, easy-to-use alternative for a range of other staining protocols commonly used for microscopic analyses in plant reproductive biology.Electronic supplementary materialThe online version of this article (doi:10.1007/s00497-015-0267-1) contains supplementary material, which is available to authorized users.

A simple and compact fluorescence detection system for capillary electrophoresis and its application to food analysis

A novel fluorescence detection system for CE was described and evaluated. Two miniature laser pointers were used as the excitation source. A Y-style optical fiber was used to transmit the excitation light and a four-branch optical fiber was used to collect the fluorescence. The optical fiber and optical filter were imported into a photomultiplier tube without any extra fixing device. A simplified PDMS detection cell was designed with guide channels through which the optical fibers were easily aligned to the detection window of separation capillary. According to different requirements, laser pointers and different filters were selected by simple switching and replacement. The fluorescence from four different directions was collected at the same detecting point. Thus, the sensitivity was enhanced without peak broadening. The fluorescence detection system was simple, compact, low-cost, and highly sensitive, with its functionality demonstrated by the separation and determination of red dyes and fluorescent whitening agents. The detection limit of rhodamine 6G was 7.7 nM (S/N = 3). The system was further applied to determine illegal food dyes. The CE system is potentially eligible for food safety analysis.