The Experts below are selected from a list of 11997 Experts worldwide ranked by ideXlab platform
Takuya Nihira - One of the best experts on this subject based on the ideXlab platform.
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regulation of production of the Blue Pigment indigoidine by the pseudo γ butyrolactone receptor farr2 in streptomyces lavendulae fri 5
2016Co-Authors: Yohanes Novi Kurniawan, Shigeru Kitani, Takuya Nihira, Aya Iida, Asa Maeda, Jelger Lycklama A Nijeholt, Yong Jik LeeAbstract:The γ-butyrolactone autoregulator signaling cascade is widely distributed among Streptomyces species as an important regulatory system of secondary metabolism. In Streptomyces lavendulae FRI-5, a γ-butyrolactone autoregulator IM-2 and the IM-2 specific receptor FarA control production of the Blue Pigment indigoidine together with two types of antibiotics: d-cycloserine and the nucleoside antibiotics. Here, we demonstrated by in silico analysis that farR2 (a farA homologue), which is located in a cluster of regulatory genes including farA, belongs to the family of pseudoreceptor regulator genes, and that the expression of farR2 is controlled by the IM-2/FarA regulatory system. Disruption of farR2 resulted in delayed production of indigoidine and in transcriptional derepression of the clustered far regulatory genes. Moreover, FarR2 bound to the FarA-binding sequences in the promoter regions of the regulatory genes that were downregulated by FarR2.
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control of secondary metabolism by farx which is involved in the γ butyrolactone biosynthesis of streptomyces lavendulae fri 5
2010Co-Authors: Shigeru Kitani, Takuya Nihira, Asa Maeda, Masashi Doi, Tomohito ShimizuAbstract:The γ-butyrolactone signaling system is distributed widely among streptomycetes as an important regulatory mechanism of antibiotic production and/or morphological differentiation. IM-2 [(2R,3R,1′R)-2-(1′-hydroxybutyl)-3-hydroxymethyl-γ-butanolide] is a γ-butyrolactone that switches off the production of d-cycloserine but switches on the production of several nucleoside antibiotics as well as Blue Pigment in Streptomyces lavendulae FRI-5. farX is a member of the afsA-family genes, which are proposed to encode enzymes involved in γ-butyrolactone biosynthesis. Disruption of farX caused overproduction of d-cycloserine, and abolished production of nucleoside antibiotic and Blue Pigment with the loss of IM-2 production. The finding that all phenotypic changes observed in the farX disruptant were restored by the addition of exogenous IM-2 suggested that FarX plays a biosynthetic role in IM-2 production. Transcriptional comparison between the wild-type strain and the farX disruptant revealed that, in addition to already known genes farR1 and farR2, several other genes (farR4, farD, and farE) are under the transcriptional regulation of IM-2. Furthermore, the fact that farX transcription is under the control of IM-2 suggested that S. lavendulae FRI-5 has a fine-tuning system to control γ-butyrolactone production.
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gene replacement analysis of the butyrolactone autoregulator receptor fara reveals that fara acts as a novel regulator in secondary metabolism of streptomyces lavendulae fri 5
2001Co-Authors: Shigeru Kitani, Yasuhiro Yamada, Takuya NihiraAbstract:IM-2 [(2R,3R,1'R)-2-1'-hydroxybutyl-3-hydroxymethyl gamma-butanolide] is a gamma-butyrolactone autoregulator which, in Streptomyces lavendulae FRI-5, switches off the production of D-cycloserine but switches on the production of a Blue Pigment and several nucleoside antibiotics. To clarify the in vivo function of an IM-2-specific receptor (FarA) in the IM-2 signaling cascade of S. lavendulae FRI-5, a farA deletion mutant was constructed by means of homologous recombination. On several solid media, no significant difference in morphology was observed between the wild-type strain and the farA mutant (strain K104), which demonstrated that the IM-2-FarA system does not participate in the morphological control of S. lavendulae FRI-5. In liquid media, the farA mutant overproduced nucleoside antibiotics and produced Blue Pigment earlier than did the wild-type strain, suggesting that the FarA protein acts primarily as a negative regulator on the biosynthesis of these compounds in the absence of IM-2. However, contrary to the IM-2-dependent suppression of D-cycloserine production in the wild-type strain, overproduction of D-cycloserine was observed in the farA mutant, indicating for the first time that the presence of both IM-2 and intact FarA are necessary for the suppression of D-cycloserine biosynthesis.
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conjugal transfer of plasmid dna from escherichia coli to streptomyces lavendulae fri 5
2000Co-Authors: Shigeru Kitani, Takuya Nihira, Mervyn J Bibb, Yasuhiro YamadaAbstract:Streptomyces lavendulae FRI-5 produces the γ-butyrolactone autoregulator IM-2, which is required for nucleoside antibiotic production. We have developed a system for introducing DNA into S. lavendulae FRI-5 via conjugal transfer from Escherichia coli. Conditions were established for conjugation of the oriT- and attP-containing plasmid pSET152 from E. coli ET12567 (pUZ8002) to FRI-5. Conjugation resulted in integration of the plasmid at the chromosomal ΦC31 attB site. The frequency of intergeneric conjugation varied with the medium used. The highest frequency (1.6×10 -5 per recipient) was obtained on ISP medium 2 containing 10 mM MgCl 2 . Southern blot and phenotypic analyses of exconjugants revealed that S. lavendulae FRI-5 contains a unique ΦC31 attB site, and that integration of heterologous DNA into the attB site did not interfere with morphological differentiation or IM-2-dependent signal transduction, including the production of a Blue Pigment. This system will now enable detailed genetic analysis of the regulation of antibiotic production in S. lavendulae FRI-5.
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in vitro analysis of the butyrolactone autoregulator receptor protein fara of streptomyces lavendulae fri 5 reveals that fara acts as a dna binding transcriptional regulator that controls its own synthesis
1999Co-Authors: Shigeru Kitani, Takuya Nihira, Hiroshi Kinoshita, Yasuhiro YamadaAbstract:FarA of Streptomyces lavendulae FRI-5 is a specific receptor protein for IM-2, a butyrolactone autoregulator that controls the production of a Blue Pigment and the nucleoside antibiotics showdomycin and minimycin. Gel shift assays demonstrated that FarA binds to the farA upstream region and that this binding is abolished in the presence of IM-2. The FarA binding sequence was localized by DNase I footprinting to a 28-bp sequence located approximately 70 bp upstream of the farA translational start site. High-resolution S1 nuclease mapping of farA transcripts revealed a putative transcription start site, located at an A residue positioned 64 bp upstream from the farA translation start codon and 4 bp downstream from an Escherichia coli ς 70 -like −10 recognition region. The FarA-binding sequence overlaps this −10 region and contains the farA transcription initiation site, suggesting that FarA acts as a repressor that, in the absence of IM-2, represses transcription of farA .
Shigeru Kitani - One of the best experts on this subject based on the ideXlab platform.
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regulation of production of the Blue Pigment indigoidine by the pseudo γ butyrolactone receptor farr2 in streptomyces lavendulae fri 5
2016Co-Authors: Yohanes Novi Kurniawan, Shigeru Kitani, Takuya Nihira, Aya Iida, Asa Maeda, Jelger Lycklama A Nijeholt, Yong Jik LeeAbstract:The γ-butyrolactone autoregulator signaling cascade is widely distributed among Streptomyces species as an important regulatory system of secondary metabolism. In Streptomyces lavendulae FRI-5, a γ-butyrolactone autoregulator IM-2 and the IM-2 specific receptor FarA control production of the Blue Pigment indigoidine together with two types of antibiotics: d-cycloserine and the nucleoside antibiotics. Here, we demonstrated by in silico analysis that farR2 (a farA homologue), which is located in a cluster of regulatory genes including farA, belongs to the family of pseudoreceptor regulator genes, and that the expression of farR2 is controlled by the IM-2/FarA regulatory system. Disruption of farR2 resulted in delayed production of indigoidine and in transcriptional derepression of the clustered far regulatory genes. Moreover, FarR2 bound to the FarA-binding sequences in the promoter regions of the regulatory genes that were downregulated by FarR2.
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control of secondary metabolism by farx which is involved in the γ butyrolactone biosynthesis of streptomyces lavendulae fri 5
2010Co-Authors: Shigeru Kitani, Takuya Nihira, Asa Maeda, Masashi Doi, Tomohito ShimizuAbstract:The γ-butyrolactone signaling system is distributed widely among streptomycetes as an important regulatory mechanism of antibiotic production and/or morphological differentiation. IM-2 [(2R,3R,1′R)-2-(1′-hydroxybutyl)-3-hydroxymethyl-γ-butanolide] is a γ-butyrolactone that switches off the production of d-cycloserine but switches on the production of several nucleoside antibiotics as well as Blue Pigment in Streptomyces lavendulae FRI-5. farX is a member of the afsA-family genes, which are proposed to encode enzymes involved in γ-butyrolactone biosynthesis. Disruption of farX caused overproduction of d-cycloserine, and abolished production of nucleoside antibiotic and Blue Pigment with the loss of IM-2 production. The finding that all phenotypic changes observed in the farX disruptant were restored by the addition of exogenous IM-2 suggested that FarX plays a biosynthetic role in IM-2 production. Transcriptional comparison between the wild-type strain and the farX disruptant revealed that, in addition to already known genes farR1 and farR2, several other genes (farR4, farD, and farE) are under the transcriptional regulation of IM-2. Furthermore, the fact that farX transcription is under the control of IM-2 suggested that S. lavendulae FRI-5 has a fine-tuning system to control γ-butyrolactone production.
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gene replacement analysis of the butyrolactone autoregulator receptor fara reveals that fara acts as a novel regulator in secondary metabolism of streptomyces lavendulae fri 5
2001Co-Authors: Shigeru Kitani, Yasuhiro Yamada, Takuya NihiraAbstract:IM-2 [(2R,3R,1'R)-2-1'-hydroxybutyl-3-hydroxymethyl gamma-butanolide] is a gamma-butyrolactone autoregulator which, in Streptomyces lavendulae FRI-5, switches off the production of D-cycloserine but switches on the production of a Blue Pigment and several nucleoside antibiotics. To clarify the in vivo function of an IM-2-specific receptor (FarA) in the IM-2 signaling cascade of S. lavendulae FRI-5, a farA deletion mutant was constructed by means of homologous recombination. On several solid media, no significant difference in morphology was observed between the wild-type strain and the farA mutant (strain K104), which demonstrated that the IM-2-FarA system does not participate in the morphological control of S. lavendulae FRI-5. In liquid media, the farA mutant overproduced nucleoside antibiotics and produced Blue Pigment earlier than did the wild-type strain, suggesting that the FarA protein acts primarily as a negative regulator on the biosynthesis of these compounds in the absence of IM-2. However, contrary to the IM-2-dependent suppression of D-cycloserine production in the wild-type strain, overproduction of D-cycloserine was observed in the farA mutant, indicating for the first time that the presence of both IM-2 and intact FarA are necessary for the suppression of D-cycloserine biosynthesis.
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conjugal transfer of plasmid dna from escherichia coli to streptomyces lavendulae fri 5
2000Co-Authors: Shigeru Kitani, Takuya Nihira, Mervyn J Bibb, Yasuhiro YamadaAbstract:Streptomyces lavendulae FRI-5 produces the γ-butyrolactone autoregulator IM-2, which is required for nucleoside antibiotic production. We have developed a system for introducing DNA into S. lavendulae FRI-5 via conjugal transfer from Escherichia coli. Conditions were established for conjugation of the oriT- and attP-containing plasmid pSET152 from E. coli ET12567 (pUZ8002) to FRI-5. Conjugation resulted in integration of the plasmid at the chromosomal ΦC31 attB site. The frequency of intergeneric conjugation varied with the medium used. The highest frequency (1.6×10 -5 per recipient) was obtained on ISP medium 2 containing 10 mM MgCl 2 . Southern blot and phenotypic analyses of exconjugants revealed that S. lavendulae FRI-5 contains a unique ΦC31 attB site, and that integration of heterologous DNA into the attB site did not interfere with morphological differentiation or IM-2-dependent signal transduction, including the production of a Blue Pigment. This system will now enable detailed genetic analysis of the regulation of antibiotic production in S. lavendulae FRI-5.
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in vitro analysis of the butyrolactone autoregulator receptor protein fara of streptomyces lavendulae fri 5 reveals that fara acts as a dna binding transcriptional regulator that controls its own synthesis
1999Co-Authors: Shigeru Kitani, Takuya Nihira, Hiroshi Kinoshita, Yasuhiro YamadaAbstract:FarA of Streptomyces lavendulae FRI-5 is a specific receptor protein for IM-2, a butyrolactone autoregulator that controls the production of a Blue Pigment and the nucleoside antibiotics showdomycin and minimycin. Gel shift assays demonstrated that FarA binds to the farA upstream region and that this binding is abolished in the presence of IM-2. The FarA binding sequence was localized by DNase I footprinting to a 28-bp sequence located approximately 70 bp upstream of the farA translational start site. High-resolution S1 nuclease mapping of farA transcripts revealed a putative transcription start site, located at an A residue positioned 64 bp upstream from the farA translation start codon and 4 bp downstream from an Escherichia coli ς 70 -like −10 recognition region. The FarA-binding sequence overlaps this −10 region and contains the farA transcription initiation site, suggesting that FarA acts as a repressor that, in the absence of IM-2, represses transcription of farA .
Aiqin Wang - One of the best experts on this subject based on the ideXlab platform.
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cobalt Blue hybrid Pigment doped with magnesium derived from sepiolite
2018Co-Authors: Anjie Zhang, Aiqin WangAbstract:Abstract Owing to the scarcity in nature of cobalt ores and the disadvantages of cobalt Blue prepared via traditional solid-phase method, the high cost of cobalt Blue Pigment severely restricted their wide application in the relevant fields. Here, sepiolite was employed to fabricate the bright Blue cobalt Blue hybrid Pigment via combining chemical co-precipitation and calcination process. The introduction of sepiolite not only dramatically decreased the cost of cobalt Blue Pigment, but also enhanced its color property presumably due to the doping of magnesium derived from sepiolite. The hybrid Pigment calcined at 1100 °C for 2 h exhibited good color properties (L⁎ = 55.8, a⁎ = −2.3, b⁎ = −55.0), excellent thermal stability and suspension stability. The as-prepared hybrid Pigments as a coloring Pigment could effectively improve the heat-resistant performance after being incorporated into organosilica coating. In addition, the hybrid Pigments could be well sprayed onto various substrates via a facile procedure. Thus it is expected to apply this low-cost bright Blue cobalt Blue hybrid Pigments into various fields.
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effect of different clay minerals and calcination temperature on the morphology and color of clay coal2o4 hybrid Pigments
2015Co-Authors: Qin Wang, Aiqin WangAbstract:Clay/CoAl2O4 hybrid Pigments with different morphologies and colors have been successfully fabricated by combining the coprecipitation technique and a successive calcination step. The morphologies of the obtained hybrid Pigments are dependent on the morphologies of the inorganic clays, whereas the colors of the hybrid Pigments are largely determined by the successive calcination temperature. The results reveal that the incorporation of the two-dimensional illite–smectite mixed-layer clay is favorable for the protection of the morphologies of the hybrid Pigments from the calcination temperature compared with that of one-dimensional attapulgite. The color of the hybrid Pigments changes from atrovirens to Blue to dark Blue with increasing calcination temperature from 800 °C to 1000 °C to 1200 °C, which is similar to the famous “Maya Blue” Pigment. It can be noted that the introduction of the inorganic clays not only decreases the production cost, but also prevents aggregation and an increase in the size of CoAl2O4 nanoparticles. There is no doubt that this strategy can realize the widespread application of CoAl2O4 Pigments in the relevant fields.
Yasuhiro Yamada - One of the best experts on this subject based on the ideXlab platform.
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gene replacement analysis of the butyrolactone autoregulator receptor fara reveals that fara acts as a novel regulator in secondary metabolism of streptomyces lavendulae fri 5
2001Co-Authors: Shigeru Kitani, Yasuhiro Yamada, Takuya NihiraAbstract:IM-2 [(2R,3R,1'R)-2-1'-hydroxybutyl-3-hydroxymethyl gamma-butanolide] is a gamma-butyrolactone autoregulator which, in Streptomyces lavendulae FRI-5, switches off the production of D-cycloserine but switches on the production of a Blue Pigment and several nucleoside antibiotics. To clarify the in vivo function of an IM-2-specific receptor (FarA) in the IM-2 signaling cascade of S. lavendulae FRI-5, a farA deletion mutant was constructed by means of homologous recombination. On several solid media, no significant difference in morphology was observed between the wild-type strain and the farA mutant (strain K104), which demonstrated that the IM-2-FarA system does not participate in the morphological control of S. lavendulae FRI-5. In liquid media, the farA mutant overproduced nucleoside antibiotics and produced Blue Pigment earlier than did the wild-type strain, suggesting that the FarA protein acts primarily as a negative regulator on the biosynthesis of these compounds in the absence of IM-2. However, contrary to the IM-2-dependent suppression of D-cycloserine production in the wild-type strain, overproduction of D-cycloserine was observed in the farA mutant, indicating for the first time that the presence of both IM-2 and intact FarA are necessary for the suppression of D-cycloserine biosynthesis.
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conjugal transfer of plasmid dna from escherichia coli to streptomyces lavendulae fri 5
2000Co-Authors: Shigeru Kitani, Takuya Nihira, Mervyn J Bibb, Yasuhiro YamadaAbstract:Streptomyces lavendulae FRI-5 produces the γ-butyrolactone autoregulator IM-2, which is required for nucleoside antibiotic production. We have developed a system for introducing DNA into S. lavendulae FRI-5 via conjugal transfer from Escherichia coli. Conditions were established for conjugation of the oriT- and attP-containing plasmid pSET152 from E. coli ET12567 (pUZ8002) to FRI-5. Conjugation resulted in integration of the plasmid at the chromosomal ΦC31 attB site. The frequency of intergeneric conjugation varied with the medium used. The highest frequency (1.6×10 -5 per recipient) was obtained on ISP medium 2 containing 10 mM MgCl 2 . Southern blot and phenotypic analyses of exconjugants revealed that S. lavendulae FRI-5 contains a unique ΦC31 attB site, and that integration of heterologous DNA into the attB site did not interfere with morphological differentiation or IM-2-dependent signal transduction, including the production of a Blue Pigment. This system will now enable detailed genetic analysis of the regulation of antibiotic production in S. lavendulae FRI-5.
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in vitro analysis of the butyrolactone autoregulator receptor protein fara of streptomyces lavendulae fri 5 reveals that fara acts as a dna binding transcriptional regulator that controls its own synthesis
1999Co-Authors: Shigeru Kitani, Takuya Nihira, Hiroshi Kinoshita, Yasuhiro YamadaAbstract:FarA of Streptomyces lavendulae FRI-5 is a specific receptor protein for IM-2, a butyrolactone autoregulator that controls the production of a Blue Pigment and the nucleoside antibiotics showdomycin and minimycin. Gel shift assays demonstrated that FarA binds to the farA upstream region and that this binding is abolished in the presence of IM-2. The FarA binding sequence was localized by DNase I footprinting to a 28-bp sequence located approximately 70 bp upstream of the farA translational start site. High-resolution S1 nuclease mapping of farA transcripts revealed a putative transcription start site, located at an A residue positioned 64 bp upstream from the farA translation start codon and 4 bp downstream from an Escherichia coli ς 70 -like −10 recognition region. The FarA-binding sequence overlaps this −10 region and contains the farA transcription initiation site, suggesting that FarA acts as a repressor that, in the absence of IM-2, represses transcription of farA .
R. Giustetto - One of the best experts on this subject based on the ideXlab platform.
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host guest interactions in a sepiolite based maya Blue Pigment a spectroscopic study
2011Co-Authors: R. Giustetto, G. Ricchiardi, Kalaivani Seenivasan, Francesca Bonino, Silvia Bordiga, Michele R Chierotti, Roberto GobettoAbstract:Maya Blue Pigment forms through heating-induced encapsula- tion and bonding of indigo in microporous clays, namely, palygorskite or sepiolite.Stabilizinghost/guest interactionsinasepiolite-basedMayaBluewere investigated by means of vibrational and NMR spectroscopies and proved to be H-bonds formed between indigo reactive groups and the clay structural OH2. Indigo sorption inhibits sepiolite structural folding induced by partial OH2 loss with temperature rise, but despite this, no direct Mg/indigo bonding was detected. Encapsulation is favored by breaking of intermolecular bonds, allow- ing dye diffusion inside the clay microtunnels. H-bond formation involves both CdO/NH indigo groups, its molecule undergoing distortion and partial oxidation to dehydroindigo. Both the strength and number of sepiolite/indigo interactions are less marked than those occurring in a palygorskite-based composite. In the wider sepiolite channels, H-bonds can form only on one side of the guest molecule, whereas both sides are involved in palygorskite. Halving in bond number undermines the stability of the resulting adduct.
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crystal structure refinement of a sepiolite indigo maya Blue Pigment using molecular modelling and synchrotron diffraction
2011Co-Authors: R. Giustetto, G. Ricchiardi, O Wahyudi, Davide Levy, Jenny G VitilloAbstract:Maya Blue is an artificial Pigment used in Pre-Columbian America, renowned for its chemical stability. The Pigment can be considered a precursor of modern inclusion compounds as a hosting microporous clay (palygorskite or sepiolite) shelters the guest indigo dye (≤2 wt%) within its micro-channels. While most papers on Maya Blue are focused on the interaction between indigo and palygorskite, this study describes the Pigment structural features when sepiolite is the host structure. Synchrotron X-ray powder diffraction patterns were collected on both pristine sepiolite and sepiolite + indigo (2 wt%) Pigment. The Pigment structure was investigated with the Rietveld method, basing on both molecular mechanics and the refined structure of sepiolite. The evidence obtained shows that: (i) indigo molecules, encapsulated within the micro-tunnels, stay close to a TOT strip in order to receive H-bonds from the structural OH 2 ; (ii) there is no evidence for direct metal-oxygen bonds between the sepiolite Mg and the indigo C=O groups, as the applied heating (≤190 °C) does not remove structural OH 2 ; (iii) the indigo molecule is affected by 4-fold disorder, as it occupies only one of four partially superposed equivalent sites; (iv) indigo and the zeolitic H 2 O compete to occupy the channels; refined occupancies showed that the dye fills 27 vol% of the channels whereas 73 vol% is occupied by H 2 O. Calculated indigo weight % (1.9) is in close agreement with experimental data; (v) indigo encapsulation modifies zeolitic H 2 O sites, increasing the number and strength of mutual hydrogen bonds; (vi) difference-Fourier maps computed removing indigo contribution confirmed the position of the molecule inside the channels.
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chemical stability and dehydration behavior of a sepiolite indigo maya Blue Pigment
2011Co-Authors: R. Giustetto, O Wahyudi, Ingrid Corazzari, Francesco TurciAbstract:Abstract Sepiolite is a fibrous clay mineral which, together with palygorskite, is an end-member of the palygorskite–sepiolite polysomatic series. Both palygorskite and sepiolite are renowned in Cultural Heritage studies because when properly complexed to the indigo dye they form Maya Blue, a synthetic Blue Pigment used in Pre-Columbian America which is famous for its exceptional stability. Freshly synthesized Maya Blue-like composites can be prepared by grinding and heating such clays with indigo. The Pigment can be considered a precursor of modern inclusion compounds, with indigo molecules possibly being hosted within nano-tunnels crossing the clay frameworks, usually filled by loosely bound zeolitic H2O and tightly bound structural OH2. While the palygorskite/indigo composite has been widely studied, few papers have been focused on the analogous sepiolite-based adduct. An in-depth research was therefore planned in order to characterize the composite structural features when indigo is hosted on the sepiolite matrix, whose importance may be relevant to both the Cultural Heritage and Materials Science fields. A Maya Blue-alike composite was obtained by properly mixing and heating (190 °C) pure sepiolite with 2 wt.% synthetic indigo. SEM-EDS analysis showed the clay crystal–chemical formula to be coherent with the ideal one. Performed stability tests proved the resistance of the synthesized sepiolite + indigo Pigment to be lower than the one typical of palygorskite + indigo adducts. Concentrated HNO3 progressively decolorized and completely destroyed the Pigment structure, due to a more pronounced intrinsic fragility of the sepiolite framework compared to palygorskite. Prolonged NaOH attack did not substantially alter the Pigment colour but caused the hosting matrix to undergo a progressive phase transformation from sepiolite to loughlinite, a similar clay mineral with intra-framework Na ions. Such a transition is favoured by indigo, whose exact role has yet to be understood. Conventional thermograms recorded for both pure sepiolite and the sepiolite + indigo composite gave indirect evidence about the encapsulation of the dye within the tunnels, as the total amount of zeolitic H2O decreased in the Pigment due to the channel volume being partly occupied by indigo. Thermogravimetry coupled with gas chromatography and mass spectrometry proved that organic splinters related to fragmentation of the adsorbed indigo molecules leave the hosting matrix in the 300–500 °C temperature interval. As loss of indigo and OH2 proceeded simultaneously, it is legitimate to suppose that H-bonds may form within the clay channels between Mg-coordinated OH2 and the dye C=O/N–H groups, thus conferring to the Pigment its renowned stability.
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Pre-columbian nanotechnology: reconciling the mysteries of the maya Blue Pigment
2008Co-Authors: Gabriele Chiari, R. Giustetto, J. Druzik, Eric Doehne, G. RicchiardiAbstract:The ancient Maya combined skills in organic chemistry and mineralogy to create an important technology – the first permanent organic Pigment. The unique color and stability of Maya Blue can be explained by a new model where indigo dye fills the grooves present at the surface of palygorskite clay, forming a hydrogen bonded organic/inorganic complex. Existing theory assumes the dye is dispersed inside the channels of an opaque mineral. Based on data from thermal analysis, synchrotron and neutron diffraction, ESEM and chemical modelling calculations, our new concept of Maya Blue structure resolves this contradiction and suggests some novel possibilities for more durable, environmentally benign Pigments.