A selection of historical textile fragments from the Venetian art dealer Moisè Michelangelo Guggenheim collection, ranging from XV to XVIII century, has been investigated by means of non-invasive ...techniques in order to reveal the coloring materials. Imaging was preliminarily used to visually investigate the selected artwork fragments in order to investigate their structure and conservation conditions; Fiber Optics Reflectance Spectroscopy (FORS) allowed recognizing the main natural dyestuffs, such as indigotin and anthraquinones-based compounds, except the yellow ones, difficultly identifiable when using this non-invasive technique. Collected spectroscopic data have been also elaborated by using a clustering algorithm that permitted to group collected spectra on the basis of similar properties and evidencing their inflection point wavelength as the most influencing feature.
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•The antique dealer M. M. Guggenheim assembled a wide textile collection.•A selection of fabric fragments ranging from XV to XVIII century was studied.•FORS analysis allowed identifying dyestuffs such as indigotin and anthraquinones.•Flavonoids were found in yellow areas but no further classification was possible.•Clustering analysis allowed grouping FORS spectra according to their spectral similarities.
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•applying a method to improving the light fastness of natural curcumin dyes extracted from turmeric by encapsulation in silica matrix.•determining the optimal conditions for ...extraction of curcumin compounds by conventional (maceration, reflux) and unconventional (microwave-assisted) methods.•encapsulation into a silica matrix by by three different routes in the presence of NaOH, lysine or triethanol amine.•the light fastness of the capsules was investigated by UV–Vis and fluorescence spectroscopy.
The study shows the possibility of improving the light fastness of natural curcumin dyes extracted from turmeric by encapsulation in silica matrix. Curcumin extracts were obtained by conventional and microwave assisted extractions. Encapsulation into a silica matrix was performed by using three different routes in the presence of NaOH, lysine or triethanol amine. The curcumin loaded silica particles were characterized by SEM, EDX, FT-IR, UV–Vis and photoluminescence spectroscopy analyses. The light fastness of the curcumin capsules was further investigated by UV–Vis spectroscopy. The color description was performed by employing the CIEL*a*b* system and the color difference was calculated. The stabilization methods lead to high encapsulation efficiencies and a very good light fastness for all samples.
Potato (Solanum tuberosum) tubers stand out for their natural pigmentation granted by anthocyanins. There is currently little information about their stability in terms of concentration, antioxidant ...activity and colouration to certain storage factors; therefore, we aimed to analyse such variables during storage for four months under different pH and temperature conditions and in the presence or absence of light. In general, the most deleterious condition for maintaining total anthocyanins was under light at room temperature, which presented a decrease of ~85%. In contrast, in liquid extracts the optimal storage conditions were 4 °C in the dark, with a loss of ~4%. The antioxidant activity and colour analyses showed optimal stability in the liquid extracts. This would make it possible to deliver added value to purple fleshed potato extracts because they are a good source of natural antioxidant pigments with potential applications in the agri-food industry as an alternative to artificial dyes.
•Flesh coloured potatoes have high concentration of total phenols.•Anthocyanins in purple coloured potatoes are mainly petunidin derivatives.•We analyzed the stability of a potato extract oriented to be used in food industry.•Storage at light at room temperature strongly decreases the extract stability.•Antioxidant activity and colour are most stable in liquid extracts.
Natural dye-based dye-sensitized solar cells (DSSCs) have unrivalled benefits in cost-effective and environmentally benign photovoltaic applications. The major advantages of such natural dye-based ...DSSCs are eco-friendly, impressive low-light performance, renewable and clean energy output, and adaptable solar product integration. Although DSSCs that employ natural dyes as a photosensitizer has several benefits, they perform poorly compared to synthetic dyes based-DSSCs and standard Si-solar cells in terms of efficiency. Additionally, there is a problem in making them into useful devices for meeting daily energy needs. This review will illustrate how to improve the parameters that must be matched for the fabrication of DSSCs that use natural dyes as sensitizers to operate more effectively. The significance of the selection strategy for creating the DSSC has been also considered in this review. The total effectiveness of the device is noticeably impacted by the choice of plant components. As a result, a thorough analysis of the plant's components that have produced superior outcomes in terms of PCE has been done. Additionally, a variety of methods and elements, including extraction strategies, the solvent employed, coating strategies, immersion time, and co-sensitization, have been taken into consideration from studies in the last ten years to investigate their impact on the global performance of the DSSC device. Finally, an overview of recent developments in DSSC science is provided. It is observed that using Clathrin protein (cow brain) results in an efficiency of 1.45%, which is noticeably lower than the 9.9% efficiency reported by Ag nanoparticles doped with graphene followed by some other novel approaches. Future viewpoints have also been considered, including the employment of DSSCs in wearable technology, the application of numerous approaches to improve the PCE of DSSCs using natural dyes, and DSSCs capacity for thermochromism.
Schematic representation of the optimal conditions for highly efficient and stable DSSC and its remarkable applications. Display omitted
•Optimal conditions during dye selection, extraction, coating, electrolyte, and enhancers were discussed.•Recent advances in metal complexes, metal free organic dyes, and natural dyes were summarized with some novel innovations.•Application oriented future perspective such as laser drilling, wearables, and thermochromism were also discussed.
Finding natural food coloring options from plant-based sources to substitute artificial dyes is a challenging task because natural dyes often present low water-solubility, not very vibrant hues, and ...instability due to interactions with food ingredients. Chemometric approaches can be used to evaluate color differences and patterns resulting from natural and synthetic dyes when applied to food systems. Here, the Mixture Design and the Principal Component Analysis (PCA) were applied to evaluate the substitution of the following artificial food dyes: yolk yellow, apricot yellow, strawberry red, and tartrazine by natural dyes (water-soluble curcumin, yellow shade; Hibiscus sabdariffa extract, red shade; Spirulina platensis extract, blue/green shade), in three food simulated systems (phosphate buffer, pH 6.9; yogurt, pH 4.0 and citrate buffer, pH 3.0). The color parameters L*, a*, b*, C* and °h were determined and color difference (ΔE*) with artificial dyes resulted in 11 empirical models. PCA yielded a clear map for the identification of the closely matches natural/artificial dyes for the food simulated systems in three subregions. Furthermore, the antioxidant capacity of the natural dyes was determined by OxHLIA and TBARS. It was possible to make an assessment guide that may be useful for other food systems and dyes.
•Curcumin, hibiscus and spirulina are great sources of natural dyes.•Color difference (ΔE*) between their blends and artificial dyes was evaluated.•Mixture experimental design yielded empirical models to describe ΔE*.•Principal Component Analysis yielded a visual tool to identify color proximity.•Curcumin, hibiscus and spirulina showed antioxidant action in OxHLIA/TBARS assays.
In this research, the extraction conditions of natural dyes from Sarsaparilla root were analyzed by response surface method, and the interaction between extract factors and their significant effects ...on sarsaparilla root extraction efficiency were discussed. The main components of Sarsaparilla root extraction were investigated by ATR-FTIR and chromogenic reaction, and the stability results of Sarsaparilla root extraction indicated that sarsaparilla root extraction obtained well thermal stability within the range of 60–100 ℃ as well as acceptable pH stability. The ATR-FTIR and XPS were obtained to confirm that the cationic modifier was fixed on the cellulose fiber through covalent bonds in the synchronous inkjet printing process, and the effect of cationic modifier’s alkyl chain length on the inkjet printing performance was clarified by Gaussian simulation calculation. The colorfastness of Sarsaparilla root natural dye ink was further improved by post-mordant treatment, and the mechanism of colorfastness improvement was elucidated by UV-Vis spectrophotometer. The inkjet printed cotton fabrics with CHPTAC-8 ink and Sarsaparilla root ink indicated well UV protection (134.87) and antibacterial property against both Staphylococcus aureus (96.3 %) and Escherichia coli (99.1 %).
•The extract conditions was analyzed by response surface method.•The chemical composition of the Sarsaparilla root extract were investigated.•The inkjet printed cotton fabrics obtained well UV protection and antibacterial property.
Abstract Textile coloration is a complex process involving the interaction of dye molecules with fibers in a dye bath. Synthetic dyes pose environmental hazards, leading to increased interest in ...natural dyes sourced from plants, animals, and minerals. However, natural dyes often require mordants for application to textiles. Despite their eco‐friendliness, natural dyes can exhibit poor wash fastness on fabrics, necessitating further research to enhance their performance. This study investigates the use of mahogany sawdust extract as a natural dye for cotton coloration, focusing on the enhancement of fastness properties through metallic mordants and associated environmental risks. Mahogany sawdust, rich in flavonoids and tannins, shows promise as a sustainable alternative to synthetic dyes. The dyeing process involves the extraction of natural dyes from sawmill bio‐waste and subsequent application onto cotton fabrics using various metallic mordants. Evaluation of colorfastness properties, color strength, color coordinates, tensile strength, FTIR, and SEM analysis provides insights into the dye‐fiber interactions and fabric properties. Environmental risk assessment considers metal exhaustion onto fabric surfaces, residual metal concentrations in mordant baths, and metal content in dyeing wastewater. Overall, this study contributes to the development of sustainable dyeing processes and highlights the importance of environmental considerations in textile coloration. Highlights Mahogany sawdust extract: potential natural dye for sustainable cotton coloration. Metallic mordants enhance colorfastness and fabric durability in dyeing processes. Comprehensive analysis reveals the intricate dynamics of dye‐fiber interactions. Environmental risk evaluation guides sustainable textile manufacturing practices. Research paves the way for greener, more sustainable textile industry practices globally.
A vast array of colorants obtained from natural sources such as plants, insects/animals and microbes have been scrutinized in recent past for their use in different kinds of applications. Research ...into new natural dyes sources along with eco-friendly, robust and cost-effective technologies for their processing and application have greatly aided in widening the scope of natural dyes in various traditional and advanced application disciplines. This review encompasses a summary of research performed in last 15 years (1998–2013) in different arenas of applications of natural dyes, with specific reference to technological development in natural textile dyeing and use of natural dyes in functional finishing of textiles, food coloration and dye-sensitized solar cells. In addition, some newly discovered applications of natural dyes have also been discussed.
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•Many different kinds of applications of natural dyes are under active study.•Reports technological developments in natural textile dyeing and finishing.•Natural dye-sensitized solar cells have been critically discussed.•Special attention has been given to recent developments in natural food colorants.•Some newly discovered applications of natural dyes have also been highlighted.
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