The Experts below are selected from a list of 1374 Experts worldwide ranked by ideXlab platform
Carl J Douglas - One of the best experts on this subject based on the ideXlab platform.
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role of glycosyltransferases in pollen wall primexine formation and exine patterning
Plant Physiology, 2017Co-Authors: Wenhua Lexcy Li, Carl J DouglasAbstract:The pollen cell wall is important for protection of male sperm from physical stresses and consists of an inner gametophyte-derived intine layer and a sporophyte-derived exine layer. The polymeric constituents of the robust exine are termed Sporopollenin. The mechanisms by which Sporopollenin is anchored onto microspores and polymerized in specific patterns are unknown, but the primexine, a transient cell wall matrix formed on the surface of microspores at the late tetrad stage, is hypothesized to play a key role. Arabidopsis (Arabidopsis thaliana) spongy (spg) and uneven pattern of exine (upex) mutants exhibit defective and irregular exine patterns. SPG2 (synonymous with IRREGULAR XYLEM9-LIKE [IRX9L]) encodes a family GT43 glycosyltransferase involved in xylan backbone biosynthesis, while UPEX1 encodes a family GT31 glycosyltransferase likely involved in galactosylation of arabinogalactan proteins. Imaging of developing irx9l microspores showed that the earliest detectable defect was in primexine formation. Furthermore, wild-type microspores contained primexine-localized epitopes indicative of the presence of xylan, but these were absent in irx9l. These data, together with the spg phenotype of a mutant in IRX14L, which also plays a role in xylan backbone elongation, indicate the presence of xylan in pollen wall primexine, which plays a role in exine patterning on the microspore surface. We observed an aberrant primexine and irregular patterns of incipient Sporopollenin deposition in upex1, suggesting that primexine-localized arabinogalactan proteins could play roles in Sporopollenin adhesion and patterning early in microspore wall development. Our data provide new insights into the biochemical and functional properties of the primexine component of the microspore cell wall.
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the biosynthesis composition and assembly of the outer pollen wall a tough case to crack
Phytochemistry, 2015Co-Authors: Teagen D Quilichini, Etienne Grienenberger, Carl J DouglasAbstract:The formation of the durable outer pollen wall, largely composed of Sporopollenin, is essential for the protection of the male gametophyte and plant reproduction. Despite its apparent strict conservation amongst land plants, the composition of Sporopollenin and the biosynthetic pathway(s) yielding this recalcitrant biopolymer remain elusive. Recent molecular genetic studies in Arabidopsis thaliana (Arabidopsis) and rice have, however, identified key genes involved in Sporopollenin formation, allowing a better understanding of the biochemistry and cell biology underlying Sporopollenin biosynthesis and pollen wall development. Herein, current knowledge of the biochemical composition of the outer pollen wall is reviewed, with an emphasis on enzymes with characterized biochemical activities in Sporopollenin and pollen coat biosynthesis. The tapetum, which forms the innermost sporophytic cell layer of the anther and envelops developing pollen, plays an essential role in Sporopollenin and pollen coat formation. Recent studies show that several tapetum-expressed genes encode enzymes that metabolize fatty acid derived compounds to form putative Sporopollenin precursors, including tetraketides derived from fatty acyl-CoA starter molecules, but analysis of mutants defective in pollen wall development indicate that other components are also incorporated into Sporopollenin. Also highlighted are the many uncertainties remaining in the development of a Sporopollenin-fortified pollen wall, particularly in relation to the mechanisms of Sporopollenin precursor transport and assembly into the patterned form of the pollen wall. A working model for Sporopollenin biosynthesis is proposed based on the data obtained largely from studies of Arabidopsis, and future challenges to complete our understanding of pollen wall biology are outlined.
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Sporopollenin monomer biosynthesis in arabidopsis
Journal of Plant Biology, 2013Co-Authors: Sungsoo Kim, Carl J DouglasAbstract:Land plants have evolved aliphatic biopolymers that protect their cell surfaces against dehydration, pathogens, and chemical and physical damage. In flowering plants, a critical event during pollen maturation is the formation of the pollen surface structure. The pollen wall consists essentially of the microspore-derived intine and the sporophyte-derived exine. The major component of the exine is termed Sporopollenin, a complex biopolymer. The chemical composition of Sporopollenin remains poorlycharacterized because it is extremely resistant to chemical and biological degradation procedures. Recent characterization of Arabidopsis thaliana genes and corresponding enzymes involved in exine formation has demonstrated that the Sporopollenin polymer consists of phenolic and fatty acid-derived constituents that are covalently coupled by ether and ester linkages. This review illuminates the outlines of a biosynthetic pathway involved in generating monomer constituents of the Sporopollenin biopolymer component of the pollen wall.
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ppascl a moss ortholog of anther specific chalcone synthase like enzymes is a hydroxyalkylpyrone synthase involved in an evolutionarily conserved Sporopollenin biosynthesis pathway
New Phytologist, 2011Co-Authors: Che C Colpitts, Carl J Douglas, Sungsoo Kim, Sarah E Posehn, Christina Jepson, Sun Young Kim, Gertrud Wiedemann, Ralf Reski, Andrew G H Wee, Daeyeon SuhAbstract:Summary • Sporopollenin is the main constituent of the exine layer of spore and pollen walls. Recently, several Arabidopsis genes, including polyketide synthase A (PKSA), which encodes an anther-specific chalcone synthase-like enzyme (ASCL), have been shown to be involved in Sporopollenin biosynthesis. The genome of the moss Physcomitrella patens contains putative orthologs of the Arabidopsis Sporopollenin biosynthesis genes. • We analyzed available P. patens expressed sequence tag (EST) data for putative moss orthologs of the Arabidopsis genes of Sporopollenin biosynthesis and studied the enzymatic properties and reaction mechanism of recombinant PpASCL, the P. patens ortholog of Arabidopsis PKSA. We also generated structure models of PpASCL and Arabidopsis PKSA to study their substrate specificity. • Physcomitrella patens orthologs of Arabidopsis genes for Sporopollenin biosynthesis were found to be expressed in the sporophyte generation. Similarly to Arabidopsis PKSA, PpASCL condenses hydroxy fatty acyl-CoA esters with malonyl-CoA and produces hydroxyalkyl a-pyrones that probably serve as building blocks of Sporopollenin. The ASCL-specific set of Gly-Gly-Ala residues predicted by the models to be located at the floor of the putative active site is proposed to serve as the opening of an acyl-binding tunnel in ASCL. • These results suggest that ASCL functions together with other sporophytespecific enzymes to provide polyhydroxylated precursors of Sporopollenin in a pathway common to land plants.
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atp binding cassette transporter g26 is required for male fertility and pollen exine formation in arabidopsis
Plant Physiology, 2010Co-Authors: Teagen D Quilichini, Michael Friedmann, Lacey A Samuels, Carl J DouglasAbstract:The highly resistant biopolymer, Sporopollenin, gives the outer wall (exine) of spores and pollen grains their unparalleled strength, shielding these structures from terrestrial stresses. Despite a limited understanding of the composition of Sporopollenin, it appears that the synthesis of Sporopollenin occurs in the tapetum and requires the transport of one or more Sporopollenin constituents to the surface of developing microspores. Here, we describe ABCG26, a member of the ATP-binding cassette (ABC) transporter superfamily, which is required for pollen exine formation in Arabidopsis (Arabidopsis thaliana). abcg26 mutants are severely reduced in fertility, with most siliques failing to produce seeds by self-fertilization and mature anthers failing to release pollen. Transmission electron microscopy analyses revealed an absence of an exine wall on abcg26-1 mutant microspores. Phenotypic abnormalities in pollen wall formation were first apparent in early uninucleate microspores as a lack of exine formation and Sporopollenin deposition. Additionally, the highest levels of ABCG26 mRNA were in the tapetum, during early pollen wall formation, Sporopollenin biosynthesis, and Sporopollenin deposition. Accumulations resembling the trilamellar lipidic coils in the abcg11 and abcg12 mutants defective in cuticular wax export were observed in the anther locules of abcg26 mutants. A yellow fluorescent protein-ABCG26 protein was localized to the endoplasmic reticulum and plasma membrane. Our results show that ABCG26 plays a critical role in exine formation and pollen development and are consistent with a model by which ABCG26 transports Sporopollenin precursors across the tapetum plasma membrane into the locule for polymerization on developing microspore walls.
Murat Kaya - One of the best experts on this subject based on the ideXlab platform.
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controlled release and anti proliferative effect of imatinib mesylate loaded Sporopollenin microcapsules extracted from pollens of betula pendula
International Journal of Biological Macromolecules, 2017Co-Authors: Idris Sargin, Lalehan Akyuz, Talip Ceter, Murat Kaya, Gamze Tan, Kevser Yildirim, Seymanur Ertosun, Gozde Hatun Aydin, Muge TopalAbstract:Sporopollenin is a promising material for drug encapsulation due to its excellent properties; uniformity in size, non-toxicity, chemically and thermally resilient nature. Herein, morphologically intact Sporopollenin microcapsules were extracted from Betula pendula pollens. Cancer therapeutic agent (imatinib mesylate) was loaded into the microcapsules. The encapsulation efficiency by passive loading technique was found to be 21.46%. Release behaviour of the drug from microcapsules was found to be biphasic, with an initial fast release followed by a slower rate of release. Imatinib mesylate release from the drug itself (control) was faster than from imatinib mesylate-loaded Sporopollenin microcapsules. The release profiles for both free and entrapped drug samples were significantly slower and more controlled in PBS buffer (pH 7.4) than in HCl (pH 1.2) buffer. Cumulative drug release from IM-MES-loaded Sporopollenin microcapsules was found to be 65% within 24h for PBS, whereas release from the control was completed within 1h. Also, a complete dissolution of control in HCl buffer was observed within first 30min. MTT assay revealed that drug-loaded microcapsules were effective on WiDr human colon carcinoma cell line. B. pendula Sporopollenin can be suggested as an effective carrier for oral delivery of imatinib mesylate.
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newly isolated Sporopollenin microcages from platanus orientalis pollens as a vehicle for controlled drug delivery
Materials Science and Engineering: C, 2017Co-Authors: Muhammad Mujtaba, Idris Sargin, Lalehan Akyuz, Talip Ceter, Murat KayaAbstract:Sporopollenin microcages were produced from the pollens of Platanus orientalis. Paracetamol was loaded into the microcages. Pollen, Sporopollenin, paracetamol and paracetamol-loaded Sporopollenin microcages were characterized with FT-IR, TGA and SEM. The analytical analyses demonstrated that Sporopollenin microcages were structurally intact, highly reticulated and thermally stable. The loading efficiency of the Sporopollenin microcages was found to be 8.2% using the passive loading technique and 23.7% via evaporating loading technique. In vitro release and kinetics studies were performed to test the suitability of Sporopollenin microcages for loading. These studies revealed that Sporopollenin from P. orientalis can be suggested as a suitable carrier for drug loading and controlled release studies.
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incorporation of Sporopollenin enhances acid base durability hydrophobicity and mechanical antifungal and antioxidant properties of chitosan films
Journal of Industrial and Engineering Chemistry, 2017Co-Authors: Murat Kaya, Muhammad Mujtaba, Idris Sargin, Lalehan Akyuz, Asier M Salaberria, Jalel Labidi, Yavuz Selim Cakmak, Behlul Koc, Talat Baran, Talip CeterAbstract:Abstract Sporopollenin-chitosan blend films were produced for the first time. Sporopollenin is a robust structural component of plant pollens exhibiting excellent features such as nontoxicity, biodegradability, biocompatibility, high thermal stability, durability to strong acid and base solutions and homogeneity in size. To benefit from these advantages, Sporopollenin samples obtained from Betula pendula (silver birch) were incorporated into chitosan film at different concentration; 10, 20 and 40 mg in 100 mL chitosan gel (1%). Stereo microscopy, FT-IR and TG/DTG analyses showed that Sporopollenin was successfully incorporated into the chitosan matrix. Incorporation of Sporopollenin in gradually increasing amount into chitosan films was found advantageous in (1) enhancement in chemical durability of the films, (2) increment of hydrophobicity, (3) boosting the mechanical properties, (4) improvement of antifungal and (5) antioxidant activities. This study revealed that Sporopollenin can be suggested as an effective blend material for biodegradable edible chitosan film production.
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design and application of Sporopollenin microcapsule supported palladium catalyst remarkably high turnover frequency and reusability in catalysis of biaryls
Joint International Conference on Information Sciences, 2017Co-Authors: Talat Baran, Idris Sargin, Murat Kaya, Ayfer Mentes, Talip CeterAbstract:Bio-based catalyst support materials with high thermal and structural stability are desired for catalysts systems requiring harsh conditions. In this study, a thermally stable palladium catalyst (up to 440°C) was designed from Sporopollenin, which occurs naturally in the outer exine layer of pollens and is widely acknowledged as chemically very stable and inert biological material. Catalyst design procedure included (1) extraction of Sporopollenin microcapsules from Betula pendula pollens (∼25μm), (2) amino-functionalisation of the microcapsules, (3) Schiff base modification and (4) preparation of Pd(II) catalyst. The catalytic activity of the Sporopollenin microcapsule supported palladium catalyst was tested in catalysis of biaryls by following a fast, simple and green microwave-assisted method. We recorded outstanding turnover number (TON: 40,000) and frequency (TOF: 400,000) for the catalyst in Suzuki coupling reactions. The catalyst proved to be reusable at least in eight cycles. The catalyst can be suggested for different catalyst systems due to its thermal and structural durability, reusability, inertness to air and its eco-friendly nature.
Daeyeon Suh - One of the best experts on this subject based on the ideXlab platform.
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ppascl the physcomitrella patens anther specific chalcone synthase like enzyme implicated in Sporopollenin biosynthesis is needed for integrity of the moss spore wall and spore viability
PLOS ONE, 2016Co-Authors: Rhys M Daku, Fazle Rabbi, Josef Buttigieg, Ian M Coulson, Derrick Horne, Garnet Martens, Neil W Ashton, Daeyeon SuhAbstract:Sporopollenin is the main constituent of the exine layer of spore and pollen walls. The anther-specific chalcone synthase-like (ASCL) enzyme of Physcomitrella patens, PpASCL, has previously been implicated in the biosynthesis of Sporopollenin, the main constituent of exine and perine, the two outermost layers of the moss spore cell wall. We made targeted knockouts of the corresponding gene, PpASCL, and phenotypically characterized ascl sporophytes and spores at different developmental stages. Ascl plants developed normally until late in sporophytic development, when the spores produced were structurally aberrant and inviable. The development of the ascl spore cell wall appeared to be arrested early in microspore development, resulting in small, collapsed spores with altered surface morphology. The typical stratification of the spore cell wall was absent with only an abnormal perine recognisable above an amorphous layer possibly representing remnants of compromised intine and/or exine. Equivalent resistance of the spore walls of ascl mutants and the control strain to acetolysis suggests the presence of chemically inert, defective Sporopollenin in the mutants. Anatomical abnormalities of late-stage ascl sporophytes include a persistent large columella and an air space incompletely filled with spores. Our results indicate that the evolutionarily conserved PpASCL gene is needed for proper construction of the spore wall and for normal maturation and viability of moss spores.
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ppascl a moss ortholog of anther specific chalcone synthase like enzymes is a hydroxyalkylpyrone synthase involved in an evolutionarily conserved Sporopollenin biosynthesis pathway
New Phytologist, 2011Co-Authors: Che C Colpitts, Carl J Douglas, Sungsoo Kim, Sarah E Posehn, Christina Jepson, Sun Young Kim, Gertrud Wiedemann, Ralf Reski, Andrew G H Wee, Daeyeon SuhAbstract:Summary • Sporopollenin is the main constituent of the exine layer of spore and pollen walls. Recently, several Arabidopsis genes, including polyketide synthase A (PKSA), which encodes an anther-specific chalcone synthase-like enzyme (ASCL), have been shown to be involved in Sporopollenin biosynthesis. The genome of the moss Physcomitrella patens contains putative orthologs of the Arabidopsis Sporopollenin biosynthesis genes. • We analyzed available P. patens expressed sequence tag (EST) data for putative moss orthologs of the Arabidopsis genes of Sporopollenin biosynthesis and studied the enzymatic properties and reaction mechanism of recombinant PpASCL, the P. patens ortholog of Arabidopsis PKSA. We also generated structure models of PpASCL and Arabidopsis PKSA to study their substrate specificity. • Physcomitrella patens orthologs of Arabidopsis genes for Sporopollenin biosynthesis were found to be expressed in the sporophyte generation. Similarly to Arabidopsis PKSA, PpASCL condenses hydroxy fatty acyl-CoA esters with malonyl-CoA and produces hydroxyalkyl a-pyrones that probably serve as building blocks of Sporopollenin. The ASCL-specific set of Gly-Gly-Ala residues predicted by the models to be located at the floor of the putative active site is proposed to serve as the opening of an acyl-binding tunnel in ASCL. • These results suggest that ASCL functions together with other sporophytespecific enzymes to provide polyhydroxylated precursors of Sporopollenin in a pathway common to land plants.
Teagen D Quilichini - One of the best experts on this subject based on the ideXlab platform.
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the toughest material in the plant kingdom an update on Sporopollenin
Frontiers in Plant Science, 2021Co-Authors: Etienne Grienenberger, Teagen D QuilichiniAbstract:The extreme chemical and physical recalcitrance of Sporopollenin deems this biopolymer among the most resilient organic materials on Earth. As the primary material fortifying spore and pollen cell walls, Sporopollenin is touted as a critical innovation in the progression of plant life to a terrestrial setting. Although crucial for its protective role in plant reproduction, the inert nature of Sporopollenin has challenged efforts to determine its composition for decades. Revised structural, chemical, and genetic experimentation efforts have produced dramatic advances in elucidating the molecular structure of this biopolymer and the mechanisms of its synthesis. Bypassing many of the challenges with material fragmentation and solubilization, insights from functional characterizations of Sporopollenin biogenesis in planta, and in vitro, through a gene-targeted approach suggest a backbone of polyhydroxylated polyketide-based subunits and remarkable conservation of biochemical pathways for Sporopollenin biosynthesis across the plant kingdom. Recent optimization of solid-state NMR and targeted degradation methods for Sporopollenin analysis confirms polyhydroxylated α-pyrone subunits, as well as hydroxylated aliphatic units, and unique cross-linkage heterogeneity. We examine the cross-disciplinary efforts to solve the Sporopollenin composition puzzle and illustrate a working model of Sporopollenin's molecular structure and biosynthesis. Emerging controversies and remaining knowledge gaps are discussed, including the degree of aromaticity, cross-linkage profiles, and extent of chemical conservation of Sporopollenin among land plants. The recent developments in Sporopollenin research present diverse opportunities for harnessing the extraordinary properties of this abundant and stable biomaterial for sustainable microcapsule applications and synthetic material designs.
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the biosynthesis composition and assembly of the outer pollen wall a tough case to crack
Phytochemistry, 2015Co-Authors: Teagen D Quilichini, Etienne Grienenberger, Carl J DouglasAbstract:The formation of the durable outer pollen wall, largely composed of Sporopollenin, is essential for the protection of the male gametophyte and plant reproduction. Despite its apparent strict conservation amongst land plants, the composition of Sporopollenin and the biosynthetic pathway(s) yielding this recalcitrant biopolymer remain elusive. Recent molecular genetic studies in Arabidopsis thaliana (Arabidopsis) and rice have, however, identified key genes involved in Sporopollenin formation, allowing a better understanding of the biochemistry and cell biology underlying Sporopollenin biosynthesis and pollen wall development. Herein, current knowledge of the biochemical composition of the outer pollen wall is reviewed, with an emphasis on enzymes with characterized biochemical activities in Sporopollenin and pollen coat biosynthesis. The tapetum, which forms the innermost sporophytic cell layer of the anther and envelops developing pollen, plays an essential role in Sporopollenin and pollen coat formation. Recent studies show that several tapetum-expressed genes encode enzymes that metabolize fatty acid derived compounds to form putative Sporopollenin precursors, including tetraketides derived from fatty acyl-CoA starter molecules, but analysis of mutants defective in pollen wall development indicate that other components are also incorporated into Sporopollenin. Also highlighted are the many uncertainties remaining in the development of a Sporopollenin-fortified pollen wall, particularly in relation to the mechanisms of Sporopollenin precursor transport and assembly into the patterned form of the pollen wall. A working model for Sporopollenin biosynthesis is proposed based on the data obtained largely from studies of Arabidopsis, and future challenges to complete our understanding of pollen wall biology are outlined.
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atp binding cassette transporter g26 is required for male fertility and pollen exine formation in arabidopsis
Plant Physiology, 2010Co-Authors: Teagen D Quilichini, Michael Friedmann, Lacey A Samuels, Carl J DouglasAbstract:The highly resistant biopolymer, Sporopollenin, gives the outer wall (exine) of spores and pollen grains their unparalleled strength, shielding these structures from terrestrial stresses. Despite a limited understanding of the composition of Sporopollenin, it appears that the synthesis of Sporopollenin occurs in the tapetum and requires the transport of one or more Sporopollenin constituents to the surface of developing microspores. Here, we describe ABCG26, a member of the ATP-binding cassette (ABC) transporter superfamily, which is required for pollen exine formation in Arabidopsis (Arabidopsis thaliana). abcg26 mutants are severely reduced in fertility, with most siliques failing to produce seeds by self-fertilization and mature anthers failing to release pollen. Transmission electron microscopy analyses revealed an absence of an exine wall on abcg26-1 mutant microspores. Phenotypic abnormalities in pollen wall formation were first apparent in early uninucleate microspores as a lack of exine formation and Sporopollenin deposition. Additionally, the highest levels of ABCG26 mRNA were in the tapetum, during early pollen wall formation, Sporopollenin biosynthesis, and Sporopollenin deposition. Accumulations resembling the trilamellar lipidic coils in the abcg11 and abcg12 mutants defective in cuticular wax export were observed in the anther locules of abcg26 mutants. A yellow fluorescent protein-ABCG26 protein was localized to the endoplasmic reticulum and plasma membrane. Our results show that ABCG26 plays a critical role in exine formation and pollen development and are consistent with a model by which ABCG26 transports Sporopollenin precursors across the tapetum plasma membrane into the locule for polymerization on developing microspore walls.
Idris Sargin - One of the best experts on this subject based on the ideXlab platform.
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controlled release and anti proliferative effect of imatinib mesylate loaded Sporopollenin microcapsules extracted from pollens of betula pendula
International Journal of Biological Macromolecules, 2017Co-Authors: Idris Sargin, Lalehan Akyuz, Talip Ceter, Murat Kaya, Gamze Tan, Kevser Yildirim, Seymanur Ertosun, Gozde Hatun Aydin, Muge TopalAbstract:Sporopollenin is a promising material for drug encapsulation due to its excellent properties; uniformity in size, non-toxicity, chemically and thermally resilient nature. Herein, morphologically intact Sporopollenin microcapsules were extracted from Betula pendula pollens. Cancer therapeutic agent (imatinib mesylate) was loaded into the microcapsules. The encapsulation efficiency by passive loading technique was found to be 21.46%. Release behaviour of the drug from microcapsules was found to be biphasic, with an initial fast release followed by a slower rate of release. Imatinib mesylate release from the drug itself (control) was faster than from imatinib mesylate-loaded Sporopollenin microcapsules. The release profiles for both free and entrapped drug samples were significantly slower and more controlled in PBS buffer (pH 7.4) than in HCl (pH 1.2) buffer. Cumulative drug release from IM-MES-loaded Sporopollenin microcapsules was found to be 65% within 24h for PBS, whereas release from the control was completed within 1h. Also, a complete dissolution of control in HCl buffer was observed within first 30min. MTT assay revealed that drug-loaded microcapsules were effective on WiDr human colon carcinoma cell line. B. pendula Sporopollenin can be suggested as an effective carrier for oral delivery of imatinib mesylate.
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newly isolated Sporopollenin microcages from platanus orientalis pollens as a vehicle for controlled drug delivery
Materials Science and Engineering: C, 2017Co-Authors: Muhammad Mujtaba, Idris Sargin, Lalehan Akyuz, Talip Ceter, Murat KayaAbstract:Sporopollenin microcages were produced from the pollens of Platanus orientalis. Paracetamol was loaded into the microcages. Pollen, Sporopollenin, paracetamol and paracetamol-loaded Sporopollenin microcages were characterized with FT-IR, TGA and SEM. The analytical analyses demonstrated that Sporopollenin microcages were structurally intact, highly reticulated and thermally stable. The loading efficiency of the Sporopollenin microcages was found to be 8.2% using the passive loading technique and 23.7% via evaporating loading technique. In vitro release and kinetics studies were performed to test the suitability of Sporopollenin microcages for loading. These studies revealed that Sporopollenin from P. orientalis can be suggested as a suitable carrier for drug loading and controlled release studies.
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incorporation of Sporopollenin enhances acid base durability hydrophobicity and mechanical antifungal and antioxidant properties of chitosan films
Journal of Industrial and Engineering Chemistry, 2017Co-Authors: Murat Kaya, Muhammad Mujtaba, Idris Sargin, Lalehan Akyuz, Asier M Salaberria, Jalel Labidi, Yavuz Selim Cakmak, Behlul Koc, Talat Baran, Talip CeterAbstract:Abstract Sporopollenin-chitosan blend films were produced for the first time. Sporopollenin is a robust structural component of plant pollens exhibiting excellent features such as nontoxicity, biodegradability, biocompatibility, high thermal stability, durability to strong acid and base solutions and homogeneity in size. To benefit from these advantages, Sporopollenin samples obtained from Betula pendula (silver birch) were incorporated into chitosan film at different concentration; 10, 20 and 40 mg in 100 mL chitosan gel (1%). Stereo microscopy, FT-IR and TG/DTG analyses showed that Sporopollenin was successfully incorporated into the chitosan matrix. Incorporation of Sporopollenin in gradually increasing amount into chitosan films was found advantageous in (1) enhancement in chemical durability of the films, (2) increment of hydrophobicity, (3) boosting the mechanical properties, (4) improvement of antifungal and (5) antioxidant activities. This study revealed that Sporopollenin can be suggested as an effective blend material for biodegradable edible chitosan film production.
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design and application of Sporopollenin microcapsule supported palladium catalyst remarkably high turnover frequency and reusability in catalysis of biaryls
Joint International Conference on Information Sciences, 2017Co-Authors: Talat Baran, Idris Sargin, Murat Kaya, Ayfer Mentes, Talip CeterAbstract:Bio-based catalyst support materials with high thermal and structural stability are desired for catalysts systems requiring harsh conditions. In this study, a thermally stable palladium catalyst (up to 440°C) was designed from Sporopollenin, which occurs naturally in the outer exine layer of pollens and is widely acknowledged as chemically very stable and inert biological material. Catalyst design procedure included (1) extraction of Sporopollenin microcapsules from Betula pendula pollens (∼25μm), (2) amino-functionalisation of the microcapsules, (3) Schiff base modification and (4) preparation of Pd(II) catalyst. The catalytic activity of the Sporopollenin microcapsule supported palladium catalyst was tested in catalysis of biaryls by following a fast, simple and green microwave-assisted method. We recorded outstanding turnover number (TON: 40,000) and frequency (TOF: 400,000) for the catalyst in Suzuki coupling reactions. The catalyst proved to be reusable at least in eight cycles. The catalyst can be suggested for different catalyst systems due to its thermal and structural durability, reusability, inertness to air and its eco-friendly nature.
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chitosan Sporopollenin microcapsules preparation characterisation and application in heavy metal removal
International Journal of Biological Macromolecules, 2015Co-Authors: Idris Sargin, Gulsin ArslanAbstract:Use of natural polymers as biosorbents for heavy metal removal is advantageous. This paper reports a study aiming to design a novel biosorbent from two biomacromolecules; chitosan, a versatile derivative of chitin, and Sporopollenin, a biopolymer with excellent mechanical properties and great resistance to chemical and biological attack. Chitosan/Sporopollenin microcapsules were prepared via cross-linking and characterised by employing scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. Sorption performance of the microcapsules and the plain chitosan beads were tested for Cu(II), Cd(II), Cr(III), Ni(II) and Zn(II) ions at different metal ion concentration, pH, amount of sorbent, temperature and sorption time. The adsorption pattern followed Langmuir isotherm model and the sorption capacity of the chitosan/Sporopollenin microcapsules was found to be Cu(II): 1.34, Cd(II): 0.77, Cr(III): 0.99, Ni(II): 0.58 and Zn(II): 0.71 mmol g(-1). Plain chitosan beads showed higher affinity for the ions; Cu(II): 1.46, Cr(III): 1.16 and Ni(II): 0.81 mmol g(-1) but lower for Cd(II): 0.15 and Zn(II): 0.25 mmol g(-1). Sporopollenin enhanced Cd(II) and Zn(II) ions sorption capacity of the chitosan microcapsules. Chitosan/Sporopollenin microcapsules can be used in Cd(II) and Zn(II) metal removal.
