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In this study, SrCuSi4O10 powders were synthesized by a complex polymerization method and the effect of Ca addition on the crystal structure and optical properties in the visible and near-infrared regions was examined. Crystalline SrCuSi4O10 was formed at 1,000 °C in air. From the X-ray diffraction measurements, the (002) and (004) reflections of SrCuSi4O10 shifted to higher angles, and the lattice parameter (a and c) decreased with the addition of Ca, suggesting that Ca was successfully introduced into SrCuSi4O10. However, the lattice constant of SrCuSi4O10 increased with further addition of Ca to 10 mol%. Optical measurements of SrCuSi4O10 identified three optical absorption bands in the visible light region, attributed to the d--d transition of Cu2+: namely ²B1g → ²B2g (540 nm), ²B1g → ²Eg (628 nm), and ²B1g → ²A1g (800 nm). The addition of Ca decreased the intensity of these absorptions. The -b* value, which indicates blueness, was estimated using the L*a*b* color system, and SrCuSi4O10 with 5 mol% Ca showed the highest value among the measured samples. On the other hand, the reflectance of SrCuSi4O10 in the near-infrared region increased significantly with the addition of Ca. These results indicate that Ca addition is effective in improving the blue coloration and near-infrared reflectivity of SrCuSi4O10. [ABSTRACT FROM AUTHOR]

Due to the importance of optimizing the manufacture of ceramic pigments, motivated by the increase in prices of both raw materials and energy, and the need to control manufacturing parameters to obtain optimal conditions for the preparation of ceramic inks, two synthesis routes (traditional route and coprecipitation) and two calcination methods (traditional oven and microwave oven) are proposed to obtain the blue ceramic pigment CoAl2O4 with the aim of minimizing the use of mineralizers or flux agents and reducing energy consumption in its manufacturing. The pigments prepared were characterized by thermal analysis and structurally by XRD and SEM, with particle sizes below 300 nm observed. Finally, the colorimetric coordinates of glazed tiles with the pigments obtained were characterized. In all cases, the microwave-assisted synthesis increased the color intensity, considerably decreasing the temperature and calcination time, obtaining a particle size under 300 nm with a very narrow size distribution, and substantially improving the energy cost of its preparation and the color development of the final product. The viability of the combination of synthesis by coprecipitation and microwave calcination as a method of industrial preparation of ceramic pigments has been demonstrated.

Due to the importance of optimizing the manufacture of ceramic pigments, motivated by the increase in prices of both raw materials and energy, and the need to control manufacturing parameters to obtain optimal conditions for the preparation of ceramic inks, two synthesis routes (traditional route and coprecipitation) and two calcination methods (traditional oven and microwave oven) are proposed to obtain the blue ceramic pigment CoAl2O4 with the aim of minimizing the use of mineralizers or flux agents and reducing energy consumption in its manufacturing. The pigments prepared were characterized by thermal analysis and structurally by XRD and SEM, with particle sizes below 300 nm observed. Finally, the colorimetric coordinates of glazed tiles with the pigments obtained were characterized. In all cases, the microwave-assisted synthesis increased the color intensity, considerably decreasing the temperature and calcination time, obtaining a particle size under 300 nm with a very narrow size distribution, and substantially improving the energy cost of its preparation and the color development of the final product. The viability of the combination of synthesis by coprecipitation and microwave calcination as a method of industrial preparation of ceramic pigments has been demonstrated. [ABSTRACT FROM AUTHOR]

Aim Blue pigments have broad applications in foods, cosmetics, and clothing. However, natural blue pigments are rare. At present, the majority of blue pigments for sale are chemically synthetic. Owing to the safety risks of chemical pigments, it is an urgent demand to develop novel natural blue pigments. Methods and Results The fermentation medium and culture conditions of blue pigment produced by Quambalaria cyanescens QY229 were optimized by Plackett–Burman (PB) experimental design and response surface methodology (RSM) for the first time. The stability, bioactivity, and toxicity of the obtained blue pigment were studied after isolation and purification. Conclusion The results showed that the optimal fermentation parameters were 34.61 g·L−1 of peptone concentration, 31.67°C of growing temperature, and 72.33 mL of medium volume in a 250-mL flask, and the yield of blue pigment reached 348.2 ± 7.1 U·mL−1. QY229 blue pigment is stable to light, heat, pH, most metal ions, and additives, and has certain antioxidant and inhibitory activity of α-glucosidase in vitro. QY229 blue pigment at concentrations of 0–1.25 mg·mL−1 was nontoxic to Caenorhabditis elegans in an acute toxicity trial. [ABSTRACT FROM AUTHOR]

Traditional Serbian religious art originated in Byzantine culture and conserved Byzantine elements until modern times. However, since the end of the 17th century, many changes in traditional icon painting have been introduced. Previous studies focused on the changes in iconography and style, but very little attention was paid to the changes in painting materials and techniques. This research focuses on the blue pigments on icons from the first half of the 18th century. Eight icons with blue areas of a different hue were selected for the study. Due to its rarity in nature, price, and iconographical importance, the blue pigment was particularly praised by painters. Therefore, the choice of the blue pigment can be related to historical information to trace influences and the development of the painter's practice. Imaging techniques, several portable, non-destructive analytical techniques, such as XRF and FTIR, followed by optical microscopy and SEM-EDX analysis of the samples were used to characterize blue pigments and the painting technique. An analysis showed that icon painters at the beginning of the 18th century used pigments such as azurite, an indigo-organic colourant of plant origin, and Prussian blue. Contrary to the traditional belief that natural ultramarine blue was used, it was not confirmed in any studied examples. [ABSTRACT FROM AUTHOR]

Roses (Rosa hybrida) are a highly merchandised flower but lack blue varieties. Overexpression of the flavonoid 3′,5′-hydroxylase (F3′5′H) gene can increase the accumulation of blue pigment (delphinidin anthocyanin). However, sometimes the effect of F3′5′H gene alone is inadequate for producing blue flowers. Furthermore, the internal environment of the cell, such as an increase in pH, can also help the conversion of anthocyanins to blue pigments. Nonetheless, genetic engineering methods can simultaneously introduce multiple genes at the same time to regulate the development of blue pigments to achieve the ultimate breeding goal of producing blue color in roses. In the present study, to simultaneously adjust the accumulation of delphinidin and vacuolar pH, we introduced the Viola tricolor flavonoid 3′,5′-hydroxylase (VtF3′5′H) and Rosa hybrida Na+/H+ exchanger (RhNHX) genes into the white rose line "KR056002" using Agrobacterium-mediated transformation. The quantitative real time polymerase chain reaction (qRT-PCR) results showed that the heterologous genes in the transgenic lines were highly expressed in petals and leaves, and simultaneously promoted the expression of related anthocyanin synthesis structural genes. Obvious color changes were observed in both petals and young leaves, especially when petals changed from white to red-purple. The formation of delphinidin was not detected in the petals of control plants, whereas the petals of transgenic lines had higher delphinidin content (135–214 μg/l) and increased pH value (0.45–0.53) compared with those of control plants. Key message: The introduction of heterologous VtF3′5′H and RhNHX genes into rose plants can affect the flower color by regulating the expression of anthocyanin synthesis pathway genes and internal cellular mechanisms. [ABSTRACT FROM AUTHOR]

Abstract The biosynthetic investigations of microbial natural products continuously provide powerful biocatalysts for the preparation of valuable chemicals. Practical methods for preparing (S)‐3‐aminopiperidine‐2,6‐dione (2), the pharmacophore of thalidomide (1) and its analog drugs, are highly desired. To develop a biocatalyst for producing (S)‐2, we dissected the domain functions of IdgS, which is responsible for the biosynthesis of indigoidine (3), a microbial blue pigment that consists of two 2‐like moieties. Our data supported that the L‐glutamine tethered to the indigoidine assembly line is first offloaded and cyclized by the thioesterase domain to form (S)‐2, which is then dehydrogenated by the oxidation (Ox) domain and finally dimerized to yield 3. Based on this, we developed an IdgS‐derived enzyme biocatalyst, IdgS‐Ox* R539A, for preparing enantiomerically pure (S)‐2. As a proof of concept, one‐pot chemoenzymatic synthesis of 1 was achieved by combining the biocatalytic and chemical approaches.

Blue-LED light or direct sunlight induces cyclization in tryptamine-quinone hybrid compounds. Formation of a C-C bond between the C-2 atom of the indole and the bromo-naphthoquinone takes place in chloroform solution in air without the need for a photocatalyst. The reaction allows the presence of a bromine atom on the indole ring which can be used for subsequent cross coupling reactions. On the other hand, the bromine atom on the naphthoquinone is strictly necessary for the cyclization to occur. The cyclic products of these reactions are blue pigments with broad absorption in the visible region. [ABSTRACT FROM AUTHOR]

The water-soluble blue–green pigment marennine, produced and partly excreted by the diatom Haslea ostrearia, and known for a long time for its role in the greening of oysters, was isolated from the culture medium, purified, and analyzed by Nuclear Magnetic Resonance (NMR) in order to gain insight into its chemical structure. The spectra show mainly carbohydrates of a complex composition, apparently highly branched, and with a mass in the order of 10 kDa. There are, in addition, some signals of aliphatic and, much weaker, aromatic groups that present aglycons. The latter might be responsible for the color. These carbohydrates are always associated with the blue–green color and cannot be separated from it by most treatments; they are interpreted as constituting the frame of the pigment. NMR after hydrolysis identifies the most abundant monosaccharides in marennine as galactose, xylose, mannose, rhamnose, and fucose. [ABSTRACT FROM AUTHOR]

[Display omitted] • The blue change of boiled lotus rhizome discs (BLRDs) was non-enzymatic browning. • The blue pigment may be mainly due to the complexation of iron and polyphenols. • The main polyphenols that caused bluing of BLRDs were L-dopa and gallocatechin. • L-dopa-iron and catechin-iron were chelated in form of bis-complexes in this study. Boiled lotus rhizome discs (BLRDs), as common processed products of lotus rhizome, have gained increasing attention from consumers and food manufacturers. However, the blue pigment formed during boiling affects its appearance and reduces the appetite of BLRDs. In this study, the effects of polyphenols and iron contents on blue pigment formation in BLRDs in different regions and months were investigated. Results revealed that blue variation was more serious in March and April of the second year in Wuhan, and polyphenols and iron contents in these two months were significantly higher than those in other months. Then, UPLC and UV–Vis analysis showed that polyphenols causing the formation of blue pigment in BLRDs were L -dopa, gallocatechin, catechin, epigallocatechin, chlorogenic acid and epicatechin, among which L-dopa (52.450 mg/100 g in fresh lotus rhizome (FLR)) and gallocatechin (36.210 mg/100 g in FLR) possessed the greatest effect. Moreover, the ESI-Q-TOF-MS analysis of L -dopa-iron chelate and gallocatechin-iron chelate suggested that the blue pigment of BLRDs was mainly in the form of bis-complexes under boiling conditions. The study on formation mechanism of blue pigment in BLRDs can provide a reference for lotus rhizome processing. [ABSTRACT FROM AUTHOR]

Novel blue pigments based on Ba 0.956 Mg 0.912 Al 10.088- x Ni x O 17 (0 ≤ x ≤ 0.3) and Ba 0.956 Mg 0.912 Al 10.088- x Co x O 17 (0 ≤ x ≤ 0.3) solid solutions were successfully synthesized by solid state method. The XRD results confirmed the structure of the as-synthesized sample belongs to hexagonal β -alumina structure with the space group of P 6 3 / mmc. The d-d electron transitions in Ni2+/Co2+ tetrahedral sites in the visible light range are the reason for the blue colors. Then, the as-prepared blue oxides were sintered with ZrO 2 powders at 1400 °C to prepare blue zirconia ceramic materials. Based on XRD and SEM analysis, the pigment phase is stable after high-temperature sintering with ZrO 2 , and a clear grain boundary is observed. The XCT results indicate the prepared blue ceramics are dense and very small pores are rarely distributed inside the blue zirconia ceramic body. Additionally, the mechanical properties of the fabricated blue ceramics were maintained compared to pure ZrO 2 ceramic. [ABSTRACT FROM AUTHOR]

The heulandite zeolite was successfully used as the host structure for a new Co-based blue colorant ceramic pigment. The method was the ion exchange of Co and Zn cations with the host structure, which induced a heat-collapsed structure followed by a recrystallization process at 1200 °C/h. The synthesized blue pigment was coated by spraying on the surface of pre-sintered ceramic tile followed by firing at 980 °C/10min. For modification of its surface, ZnO nanoparticles (NPs) and commercial antifouling were used. The blue powder pigment and ceramic coated surface were characterized with XRD, Rietveld refinement, TGA-DTA, FE-SEM-EDS, BET-BJH, UV-VIS-NIR spectroscopy, CIEL*a*b* color measurement, water contact angle (WCA), and roughness analysis. The single-crystal Co-willemite has been achieved (b* = −45 and a* = −0.5). The blue pigment coated on the surface after being modified with ZnO NPs and antifouling revealed a superhydrophobic surface with WCA = 153.7°. Due to this, a low water sliding angle of less than 5° have achieved. The surface showed high thermal stability and adherence. The superhydrophobicity was mainly due to the micro-nanopatterned lotus leaf-like crystal structure and roughness of 3.15 μm on the surface. The surface showed 64% total reflectance from 700 to 2500 nm (UV and NIR), which resulted in a perfect candidate for a cool coating. [ABSTRACT FROM AUTHOR]

The diversity of colours is one of the most typical features of vernacular architecture. The submitted study deals with the research on the use of ultramarine on the Pannonian type of folk house, which could be found in central, southern, and south-eastern Moravia. The authors primarily proceed from the younger shift of the house. This featured, among other things, mainly the original transformation of stylistic elements, the façade segmentation, and the diversity of colours used on the frontages of residential buildings. Blue pigments were only barely available by the early nineteenth century, especially in the rural environment. The use of blue pigments flourished in vernacular architecture only after 1828, when the technique for the production of ultramarine was published. This was followed by industrial production of this pigment. The technique for the production of ultramarine, applied in the past, is described e. g. in the publication Tovární výroba barev [Factory Production of Dyes] by Jaroslav Milbauer from 1926. The treatise interconnects the cultural-historical and the technical level of the phenomenon under study. The material-analytical section is based on ethnological field research and an analysis of historical plasters using both physical-chemical methods of their identification and the knowledge of material engineering. Ethnological knowledge thus acquires a completely new dimension, and it is supplemented by new conclusions. At the same time, it is also a detailed analysis of the structure of ultramarine currently acquired on our market and an attempt at its laboratory synthesis. The result of the presented experiment with the production of blue pigment can be beneficial in practice for restoration purposes and professional analysis of historical plasters. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both polyphenol oxidase and β-glucosidase were involved in VBP formation. • Vaccinoside played as a unique bifunctional precursor to form VBPs. • 15 Amino acids helped to give VBPs (λmax 581–590 nm) of different hues. • Two synthesis pathways were proposed to interpret formation of VBPs. Since Tang dynasty in China, the fresh leaves of Vaccinium bracteatum (VBL) have been applied as natural pigment to produce black rice. However, detailed information on its biosynthetic mechanism still remained unclear. Following rice dyeing capacity assay, vaccinoside, one of iridoid glycosides, was identified as the key active compound. Increased methodical research demonstrated vaccinoside as a distinct bifunctional precursor, which could be catalyzed by polyphenol oxidase or β-glucosidase independently, followed by reaction with 15 amino acids to give blue pigments (VBPs; λmax 581–590 nm) of different hues. Two synthetic pathways of VBPs were proposed, using multiple techniques such as HPLC, HPSEC, UV–Vis spectrum and colorimeter as analysis tools. Black rice was interpreted to be prepared by cooking, using vaccinoside, intrinsic enzymes from fresh VBL and rice protein in combination. These findings promote the understanding of VBP formation mechanisms and provide an efficient method of producing novel Vaccinium blue pigments. [ABSTRACT FROM AUTHOR]

This study involved evaluating the effects of rotational impeller speed agitation (N) and specific air flow rate (Фair) on bikaverin production and on the growth of Fusarium oxysporum employing 11 bench-scale bioreactor assays. The results showed that the maximum bikaverin production (close to 300 mg L−1) was achieved after 48 h of fermentation in rice medium (20 g L−1 milled rice in water) at 28 °C with a volumetric oxygen transfer coefficient (KLa) and shear stress values of approximately 20 h−1 and 17 N m−2, respectively. We reached this combination of parameters using an N of 340 rpm and Фair of 0.935 vvm. These KLa and shear stress values can be used as references when upscaling this process. Thus, this study was important to demonstrate how the main parameters in bioreactors affect bikaverin production and it presented important indications for upscaling this bioprocess. [ABSTRACT FROM AUTHOR]

Solid solutions based on BaAl 12- x M x O 19 (M = Co2+, Ni2+) showing intense blue shades were successfully synthesized by conventional solid state reaction. Then, novel zirconia ceramic materials with intense blue hues were then prepared upon addition of 5 wt% of the synthesized chromophore to a ZrO 2 white matrix containing 5 wt% Y 2 O 3 and sintered at 1400 °C for 6 h. The colors of the BaAl 12- x Co x O 19 or BaAl 12- x Ni x O 19 are due to the d-d transitions of Co2+ or Ni2+ in tetrahedral coordination, respectively. The colored zirconia ceramics were all indexed with tetragonal phase. The coexistence of the chromophore and ZrO 2 were observed by scanning electron microscopy and energy dispersive spectrometer. The hardness of the as-synthesized blue zirconia ceramic was slightly higher as compared to the pure undoped sample. [ABSTRACT FROM AUTHOR]

In historical paintings, the detection of low amounts of pigments and dyes by Raman spectroscopy can sometimes be challenging, in particular for fluorescent dyes. This issue can be overcome by using SERS (surface-enhanced Raman spectroscopy) which takes advantage of the properties of nanostructured metal surfaces to quench fluorescence and enhance Raman signals. In this work, silver nanostars (AgNSs) are applied for the first time to real art samples, in particular to painting cross-sections, exploiting their effective SERS properties for pigment identification. The case study is the Madonna della Misericordia of the National Gallery of Parma (Italy). Cross-sections were analyzed at first by optical microscopy, SEM-EDS, and micro-Raman spectroscopy. Unfortunately, in some cross-sections, the application of conventional Raman spectroscopy was hindered by an intense background fluorescence. Therefore, AgNSs were deposited and used as SERS-active agent. The experimentation was successful, allowing us to identify a modern dye, namely copper phthalocyanine. This result, together with the detection of other modern pigments (titanium white) and expert visual examination, allowed to reconstruct the painting history, postdating its realization from the 15th century (according to the Gallery inventory) to 19th century with a heavy role of recent (middle 20th century) restoration interventions.

The water-soluble blue–green pigment marennine, produced and partly excreted by the diatom Haslea ostrearia, and known for a long time for its role in the greening of oysters, was isolated from the culture medium, purified, and analyzed by Nuclear Magnetic Resonance (NMR) in order to gain insight into its chemical structure. The spectra show mainly carbohydrates of a complex composition, apparently highly branched, and with a mass in the order of 10 kDa. There are, in addition, some signals of aliphatic and, much weaker, aromatic groups that present aglycons. The latter might be responsible for the color. These carbohydrates are always associated with the blue–green color and cannot be separated from it by most treatments; they are interpreted as constituting the frame of the pigment. NMR after hydrolysis identifies the most abundant monosaccharides in marennine as galactose, xylose, mannose, rhamnose, and fucose.

Many pigments, such as melanins, are widely distributed throughout the animal kingdom. Others have arisen as novelties in particular lineages, for example, the Green Fluorescent Protein (GFP) found in cnidarians. While GFPs, widely used as fluorescent tags in biomedical research, are the most famous cnidarian example, other novel proteins have also been identified within this phylum. A blue protein that contains a Kringle (KR) domain inserted within a Frizzled cysteine-rich domain (Fz-CRD) was previously described from the jellyfish Rhizostoma pulmo (named rpulFKz1), however little is known about this pigment’s evolution or distribution among cnidarians. We performed a systematic search for homologs of this protein in published genomes and transcriptomes of 93 cnidarians. Phylogenetic analyses revealed eight predicted proteins that possess both domains in the same arrangement and that fall within the same clade as rpulFKz1. The sequence of one of these proteins contains motifs that match sequenced peptides of Cassio Blue, the blue pigment from Cassiopea xamachana. Another one of these proteins belongs to Stomolophus meleagris, and chemical studies on blue pigments that may occur in this genus have shown similarities to rpulFKz1 and Cassio Blue. Therefore, we hypothesize that the eight rpulFKz1 homologs identified are also pigment precursors. All precursors identified were exclusive to jellyfish in the order Rhizostomeae, so we herein name this new pigment family “rhizostomins.” Not all rhizostomes analyzed are blue, however, so these rhizostomin proteins may also be responsible for other colors, or perform other biochemical and biophysical roles. Previous studies have hypothesized that cnidarian pigments are photoprotective, and this study serves as basis for future investigations not only on the function of rhizostomins, but also on potential biotechnological applications for these proteins.

New cases of blue cheese discoloration has led to recent research to identify the causal agent and factors that favor blue pigment appearing. Nonetheless, very few reports have described the source of contamination and the measurements to eradicate the microbiological source on cheese farms by determining the relation between blue discoloration on fresh cheese and the Pseudomonas fluorescens group. Thus, 60 samples from a cheese farm (cheese, equipment surfaces, tap water, and raw and pasteurized milk) were analyzed by phenotypical, MALDI-TOF, 16S rRNA sequencing and pulsed-field gel electrophoresis tests to determine the causal agent. The results obtained by pulsed-field gel electrophoresis with restriction enzymes Xba I and Spe I confirmed tap water as the initial contaminated source. The above-mentioned result was essential to avoid Pseudomonas contamination due to the most residual microorganisms being inactivated through a new disinfection program. [ABSTRACT FROM AUTHOR]

Indigoidine is a dark-blue natural pigment with application prospect and synthesized from glutamine (Gln) by series of indigoidine synthetases (IndCs). Indigoidine production can be improved by enhancing Gln pool via supplementing Gln directly or converting metabolism glutamate (Glu) to Gln by glutamine synthetase (GlnA). But, Gln is expensive, and excess Gln inhibits indigoidine production of the recombinant strain. Supplementing Glu instead of Gln may improve the productive and economic efficiency of indigoidine, but the local activities and positions of the indigoidine pathway enzymes GlnA, Sc-IndC, and the helper protein of Sc-IndC (IndB) should be well arranged. We identified the Streptomyces chromofuscus ATCC 49982 derived IndC (Sc-IndC) as an more efficient IndC compared to other IndCs applied for constructing indigoidine-producting strains, and designed series of protein scaffold complexes with architectures of PDZ, SH3, and GBD domains (PxSyG1) to arrange the pathway enzymes. The strain recruiting GlnA, Sc-IndC, and IndB on the PDZ, SH3, and GBD domains of scaffold P1S2G1, respectively, was the most efficient. In the strain, the GlnA supplied sufficient local Gln for Sc-IndC from Glu, and the generated Gln was immediately consumed by Sc-IndC to relieve cell growth inhibition caused by Gln. The optimum Glu concentration (6 g/L) for the strain was higher than those of the strains recruiting Sc-IndC on the GBD domain, which was away from the PDZ domain recruiting GlnA. The highest titer of indigoidine was 12 g/L, which was two folds of the control without scaffold (5.8 g/L). The titer is 5 g/L higher than the control without Glu supplemented (6.9 g/L), meaning that 97% of the supplemented Glu was transformed into indigoidine. The batch fermentation with the optimum strain in a 5-L reactor achieved an indigoidine titer of 14 g/L in 60 h. To our knowledge, this was the most efficient indigoidine productivity achieved so far. The optimization strategies by protein scaffold should be applicative to other pathways with complex substrate demands. Key points: •Protein scaffold systems were designed to arrange the indigoidine synthetic pathway. •The scaffold system improved supplement of Gln for indigoidine production from Glu. •The inhibition caused by excess Gln was relieved by proper designed scaffold. •The yield and titer of indigoidine was improved by arranging the pathway enzymes. [ABSTRACT FROM AUTHOR]

The blue underglaze decorations of Chinese blue-and-white porcelains are due to the use of a cobalt-based blue pigment. Nevertheless, for a same time period and production centre, wares can present wide colour variations in both hue and intensity. Fourteen Ming samples were investigated using colorimetry, Raman spectroscopy and SEM-EDS, in order to better understand the origin of these variations. The majority of the sherds dates back to the middle 15th- early 16th century. The chromogenic mechanism of the hue and intensity variations appears to be complex and multifactorial. Six main factors have been identified: the elemental composition of the pigment particles, in particular the Fe/Co ratio, the pigment spinel structure, the size as well as the distribution of the colouring particles, the environment of the pigment particles and the colour of the glaze. [ABSTRACT FROM AUTHOR]

1,4‐Diketopyrrolo[3,4‐c]pyrroles (DPPs) constitute a class of hydrogen‐bonded pigments covering a color range from yellow–orange to dark violet. We report facile dimerization of a Boc‐substituted 3,6‐dithienyl‐DPP. The formed dimer shows brilliantly blue color as a result of the expansion of the chromophore. The soluble dimer acts as latent pigment and is converted to the corresponding pigment either via thermocleavage or acidic deprotection of the Boc groups. The synthesized pigment is characterized by high migrational stability in a polymer matrix and a clear blue color. Blue with Boc: A Boc‐substituted 3,6‐dithienyl‐DPP furnished a soluble latent pigment, which can be deprotected to give the blue dimeric DPP pigment. [ABSTRACT FROM AUTHOR]

Abstract: Due to consumers'demand for natural pigments new sources have been explored, the marine environment among others. This paper studied the optimal extraction conditions and preliminary characterized a blue pigment obtained from Stomolophus meleagris jellyfish. Specimens were collected from State of Sonora seashore, at the Gulf of California, Mexico. The umbrella color was not homogeneous where a more intense blue color was observed at the edge. The pigment was obtained after tissue sonication at 35 kHz and extraction with artificial seawater, and purified by ultrafiltration through 30 and 100-kDa MCD membranes.The pigment is not a carotenoid, as concluded by its insolubility in non-polar solvents. A 100 kDa protein was associated to the chromophore, conversely with other jellyfish species where the protein moiety is around 30 kDa. This higher protein molecular weight was possible due to a multimeric glycoprotein. By using PAS staining it was concluded that this pigment includes a glycoprotein, showing similar characteristics to the blue pigment extracted from Casiopea xamachana and Rizostoma pulmo.The associated protein was separated from the pigment-protein complex using two commercial proteases. Pigment stability was followed during storage for 35 days at 4 and -20°C. The obtained partially purified pigment was efficiently extracted with 10% ethanol, stable at pH 3 to 9, but not stable to heating. [ABSTRACT FROM AUTHOR]

In dairy processing environments, many bacterial species adhere and form biofilms on surfaces and equipment, leading to foodborne illness and food spoilage. Among them, Listeria monocytogenes and Pseudomonas spp. could be present in mixed-species biofilms. This study aimed to evaluate the interactions between L. monocytogenes and P. fluorescens in biofilms simulating dairy processing conditions, as well as the capability of P. fluorescens in co-culture to produce the blue pigment in a Ricotta-based model system. The biofilm-forming capability of single- and mixed-cultures was evaluated on polystyrene (PS) and stainless steel (SS) surfaces at 12 °C for 168 h. The biofilm biomass was measured, the planktonic and sessile cells and the carbohydrates in biofilms were quantified. The biofilms were also observed through Confocal Laser Scanning Microscopy analysis. Results showed that only P. fluorescens was able to form biofilms on PS. Moreover, in dual-species biofilms at the end of the incubation time (168 h at 12 °C), a lower biomass compared to P. fluorescens mono-species was observed on PS. On SS, the biofilm cell population of L. monocytogenes was higher in the dual-species than in mono-species, particularly after 48 h. Carbohydrates quantity in the dual-species system was higher than in mono-species and was revealed also at 168 h. The production of blue pigment by P. fluorescens was revealed both in single- and co-culture after 72 h of incubation (12 °C). This work highlights the interactions between the two species, under the experimental conditions studied in the present research, which can influence biofilm formation (biomass and sessile cells) but not the capability of P. fluorescens to produce blue pigment.

Marennine is a high-value compound produced by the benthic diatom Haslea ostrearia , which could be used as an alternative to synthetic antibiotics in aquaculture. Over the last few years, however, low production rates have been impeding its exploitation. Recent progress on H. ostrearia culture devices led to the design of a particular photobioreactor (PBR) for high yield marennine production, which remained to be further studied: the objective of this study is thus to evaluate the advantages of using a submerged membrane photobioreactor (MPBR) for the culture of H. ostrearia by testing the reliability of its performances when changing strains. In addition, the impact of the decrease in cell size through time, as experienced by H. ostrearia along its life cycle, was studied in regard to marennine productivity, thus considering inter- and intra-strain variability. Using the 1 L MPBR proposed by Gargouch et al. (2022) three different strains of H. ostrearia were cultivated in a fed-batch mode and marennine was collected in a semicontinuous way (D = 0,1 d−1) with an ultrafiltration membrane immersed in the culture. Biometrics of the inocula were measured, and biomass development and marennine production were followed over 20 days of culture. Results confirmed the advantage brought by the addition of a membrane inside the culture chamber enabling to maintain a minimal productivity of 2 mg d−1, using only 3 L of fresh culture medium over a 20-day culture. Results also showed that cell downsizing along H. ostrearia life cycle did impact marennine productivity per cell, with smaller cells (i.e. older strains), displaying a 4 to 15 times increase in biovolumetric marennine productivity depending on the strain. Hypotheses explaining this increase in marennine production along the life cycle of H. ostrearia are discussed, considering also changes in the microbiome or epigenetic variations along strain life cycle. [Display omitted] • Hybrid culture process as a reliable marennine production system regardless of Haslea ostrearia strain; • Cell downsizing induces an increase in extracellular marennine production; • Marennine shading strategy is used by Haslea ostrearia in a high intensity light environment to maintain homeostasis. [ABSTRACT FROM AUTHOR]

The practice of tattooing dates back to 5000 years ago and is currently constantly growing. The most common pigment associated with tattoo complications is the red one. Another pigment, which could be associated with adverse reactions, even if less frequently than red, is blue. Traditionally, blue pigment contains cobalt, which causes allergic reactions. Here, we report a case of blue pigment granulomatous reaction in a 37‐year‐old male patient. [ABSTRACT FROM AUTHOR]

Safety concerns in the food industry have increased the demand for natural food colorants. However, the application ranges of natural blue colorants are insufficient because they are scarce in nature, and the currently available natural blue dyes are limited to water-soluble products. In this study, we investigated a fat-soluble azulene derivative isolated from the mushroom Lactarius indigo as a potential candidate for a natural blue colorant. We developed its first total synthesis, where the azulene skeleton was constructed from a pyridine derivative and an ethynyl group was converted into an isopropenyl group using zirconium complexes. Moreover, nanoparticles of the azulene derivative were prepared via reprecipitation method, and their colorant ability was investigated in aqueous solutions. The new candidate food colorant exhibited a deep-blue color in an organic solvent and aqueous dispersion.

ABSTRACT: Aims: The study was focused on Pseudomonas fluorescens strains isolated from Mozzarella cheese, with the aim of evaluating the effects of Origanum vulgare L. essential oil (OEO) on the biofilm formation and eradication, as well as on the motility and blue pigment production at 10°C. Methods and Results: Microdilution method was used to determine the minimum inhibitory and bactericidal concentration of the OEO, which ranged between 10 and 40 μl ml−1. In vitro studies demonstrated that a sublethal concentration of OEO influenced not only P. fluorescens growth and motility but also the capability to form biofilm and, in a lower degree, the biofilm eradication at 10°C. Analysis by confocal microscopy revealed a dramatic reduction in biofilm formation and thickness, with scattered damage or death of cells, stained by propidium iodide. In addition, a concentration of 5 μl ml−1 of OEO affected the motility of the cells and, in particular, their ability to swim. However, the essential oil did not inhibit the blue pigment production by any of the tested strains. Conclusions: The present findings suggest that oregano essential oil inhibits the biofilm formation of P. fluorescens strains and alters their motility. Moreover, in the preformed biofilm, OEO contributes to the detachment of the cells, deteriorating the architecture of the biofilm and reducing its thickness. Significance and Impact of the Study: The O. vulgare L. essential oil was revealed as a promising agent against biofilm formation and for its detaching; these results suggest that oregano EO could be used in the dairy food industry to control biofilm formation, as an alternative, or in combination with conventional sanitizers. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the ability of Pseudomonas spp. strains isolated from milk, dairy products and dairy plants, to produce blue pigment in situ , to form biofilm onto polystyrene surfaces and to perform different types of motility. Molecular identification revealed that, out of 72 Pseudomonas spp. isolates, P . fluorescens was the most common species (50 isolates) followed by P . putida (9), P . koreensis (4), P . brenneri (4), P . aeruginosa (2), P . granadensis (2) and P . veronii (1). The evaluation of blue colour production showed that the pigment was produced at 10 °C but not at 30 °C; in addition this character was strain- and species-dependent, with only 16 P. fluorescens strains showing blue pigment production. Most of the studied strains produced biofilm although with some differences related to the strains and the incubation temperatures. Within the most abundant isolated species ( P . fluorescens ), about 46%, 34% and 26% of the strains were able to swim, swarm and twitch, respectively. The observed relationship between biofilm formation and blue pigment production in P . fluorescens strains was statistically significant. Since these characteristics may contribute to the persistence of microorganisms in food processing environments and therefore to the contamination of food products, our results may help to focus on the control of the strains involved in the blue discolouration of dairy products. [ABSTRACT FROM AUTHOR]

This paper reports the identification of the blue pigments used in the painted stucco decoration in three Ilkhanid (1251-1335 AD) (650-736 AH) buildings in Yazd: the Madrasah of Sayed Shams-al-Dīn, the Madrasah of Sayed Kamāl-al-Dīn, and the Madrasah of Sayed Rukn-al-Dīn. The significance of these buildings lies in the fact that these are the latest extant buildings of the period in the city with such extensive painted wall stucco. For the purpose of this study, six samples were tested in total, two from each building. Four types of laboratory instrumental analysis were conducted in this study: Fourier transform infrared spectroscopy (FTIR), polarizing microscopy (PLM), X-ray fluorescence (XRF) and X-ray diffraction (XRD). Copper was found by XRF, carbonated combinations were identified as a result of FTIR analysis, blue-turquoise crystals were seen under the polarizing microscope, and an azurite phase was identified by XRD analysis. These results indicate that azurite, a blue-colored copper carbonate, has been used as a blue pigment in three Ilkhanid monuments, the madrasas of Sayed Shams-al-Dīn, Sayed Kamāl-al-Dīn, and Sayed Rukn-al-Dīn, in Yazd, Iran. [ABSTRACT FROM AUTHOR]

The application of response surface methodology combined with artificial neural network was used to estimate the optimal characteristics of nano-sized cobalt based pigment. Firstly, the nano-sized blue powder was synthesized by stoichiometric contents of cobalt and aluminum nitrates using autoignition technique. The study was conducted over a wide range of operating conditions, designed by response surface methodology, in terms of pH, fuel ratio and calcination temperature. The crystallite size, specific surface area, color behavior and crystallinity of powders were determined according to the standard methods. Secondly, several artificial neural networks were designed and then examined for prediction of pigment characteristics. The appropriate model was obtained to achieve better prediction and then the response surface methodology was applied to screen the artificial neural network output data for optimizing synthesis condition. It was concluded that the trained artificial neural network combined with response surface methodology can provide the synergetic pigment synthesis conditions. The additional validations were performed and the results showed acceptable error between the predicted and experimental data. The application of presented algorithm can be important tool for reliable synthesis nano-sized blue powder. [ABSTRACT FROM AUTHOR]