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Vinitha V, Preeyanghaa M, Anbarasu M, Neppolian B, Sivamurugan V. Chemical recycling of polyester textile wastes using silver-doped zinc oxide nanoparticles: an economical solution for circular economy. Environ Sci Pollut Res Int 2023:10.1007/s11356-023-27567-0. [PMID: 37217818 DOI: 10.1007/s11356-023-27567-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/05/2023] [Indexed: 05/24/2023]
Abstract
The waste management of polyethylene terephthalate (PET)-derived polyester (PES) textile is a global issue, and material recovery through chemical recycling can restore a circular economy. In our investigation, microwave-induced catalytic aminolysis and glycolysis of PES textile wastes using Ag-doped ZnO nanoparticles have been proposed. Ag-doped ZnO is prepared by the sol-gel method and characterised by XRD, FT-IR, UV-Vis, SEM-EDX and TEM. The reaction parameters such as PET-to-catalyst ratio, microwave power and irradiation time, temperature and catalyst recycling have been optimised. The catalyst was found to be more stable and could be recycled up to six times without losing its activity. Both the aminolysis and glycolysis of PES showed 100% conversion and afforded of bis (2-hydroxy ethylene) terephthalamide (BHETA) and bis (2-hydroxy ethylene) terephthalate (BHET), respectively. The depolymerisation of PES wastes using Ag-doped ZnO afforded BHETA and BHET for about 95 and 90%, respectively. The monomers BHET and BHETA confirmed by FT-IR, 1H NMR and mass spectroscopy. According to the findings, 2 mol% Ag-doped ZnO has higher catalytic activity.
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Affiliation(s)
- Viswanathan Vinitha
- PG and Research Department of Chemistry, Pachaiyappa's College, Chennai, 600 030, India
| | - Mani Preeyanghaa
- Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai, 603 203, India
| | - Murugan Anbarasu
- PG and Research Department of Chemistry, Pachaiyappa's College, Chennai, 600 030, India
| | - Bernaurdshaw Neppolian
- Department of Chemistry, SRM Institute of Science and Technology, Kattankulathur, Chennai, 603 203, India
| | - Vajiravelu Sivamurugan
- PG and Research Department of Chemistry, Pachaiyappa's College, Chennai, 600 030, India.
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Rammala B, Zhou N. Looking into the world's largest elephant population in search of ligninolytic microorganisms for biorefineries: a mini-review. Biotechnol Biofuels Bioprod 2022; 15:64. [PMID: 35689287 PMCID: PMC9188235 DOI: 10.1186/s13068-022-02159-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/12/2022] [Indexed: 11/24/2022]
Abstract
Gastrointestinal tracts (GIT) of herbivores are lignin-rich environments with the potential to find ligninolytic microorganisms. The occurrence of the microorganisms in herbivore GIT is a well-documented mutualistic relationship where the former benefits from the provision of nutrients and the latter benefits from the microorganism-assisted digestion of their recalcitrant lignin diets. Elephants are one of the largest herbivores that rely on the microbial anaerobic fermentation of their bulky recalcitrant low-quality forage lignocellulosic diet given their inability to break down major components of plant cells. Tapping the potential of these mutualistic associations in the biggest population of elephants in the whole world found in Botswana is attractive in the valorisation of the bulky recalcitrant lignin waste stream generated from the pulp and paper, biofuel, and agro-industries. Despite the massive potential as a feedstock for industrial fermentations, few microorganisms have been commercialised. This review focuses on the potential of microbiota from the gastrointestinal tract and excreta of the worlds' largest population of elephants of Botswana as a potential source of extremophilic ligninolytic microorganisms. The review further discusses the recalcitrance of lignin, achievements, limitations, and challenges with its biological depolymerisation. Methods of isolation of microorganisms from elephant dung and their improvement as industrial strains are further highlighted.
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Affiliation(s)
- Bame Rammala
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana.
| | - Nerve Zhou
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana.
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Ballerstedt H, Tiso T, Wierckx N, Wei R, Averous L, Bornscheuer U, O’Connor K, Floehr T, Jupke A, Klankermayer J, Liu L, de Lorenzo V, Narancic T, Nogales J, Perrin R, Pollet E, Prieto A, Casey W, Haarmann T, Sarbu A, Schwaneberg U, Xin F, Dong W, Xing J, Chen GQ, Tan T, Jiang M, Blank LM. MIXed plastics biodegradation and UPcycling using microbial communities: EU Horizon 2020 project MIX-UP started January 2020. Environ Sci Eur 2021; 33:99. [PMID: 34458054 PMCID: PMC8380104 DOI: 10.1186/s12302-021-00536-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 07/31/2021] [Indexed: 05/16/2023]
Abstract
This article introduces the EU Horizon 2020 research project MIX-UP, "Mixed plastics biodegradation and upcycling using microbial communities". The project focuses on changing the traditional linear value chain of plastics to a sustainable, biodegradable based one. Plastic mixtures contain five of the top six fossil-based recalcitrant plastics [polyethylene (PE), polyurethane (PUR), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS)], along with upcoming bioplastics polyhydroxyalkanoate (PHA) and polylactate (PLA) will be used as feedstock for microbial transformations. Consecutive controlled enzymatic and microbial degradation of mechanically pre-treated plastics wastes combined with subsequent microbial conversion to polymers and value-added chemicals by mixed cultures. Known plastic-degrading enzymes will be optimised by integrated protein engineering to achieve high specific binding capacities, stability, and catalytic efficacy towards a broad spectrum of plastic polymers under high salt and temperature conditions. Another focus lies in the search and isolation of novel enzymes active on recalcitrant polymers. MIX-UP will formulate enzyme cocktails tailored to specific waste streams and strives to enhance enzyme production significantly. In vivo and in vitro application of these cocktails enable stable, self-sustaining microbiomes to convert the released plastic monomers selectively into value-added products, key building blocks, and biomass. Any remaining material recalcitrant to the enzymatic activities will be recirculated into the process by physicochemical treatment. The Chinese-European MIX-UP consortium is multidisciplinary and industry-participating to address the market need for novel sustainable routes to valorise plastic waste streams. The project's new workflow realises a circular (bio)plastic economy and adds value to present poorly recycled plastic wastes where mechanical and chemical plastic recycling show limits.
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Affiliation(s)
- Hendrik Ballerstedt
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Till Tiso
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Nick Wierckx
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Research Center Jülich, Wilhelm Johnen Straße, 52428 Jülich, Germany
| | - Ren Wei
- Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany
| | - Luc Averous
- BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
| | - Uwe Bornscheuer
- Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany
| | - Kevin O’Connor
- BiOrbic Bioeconomy SFI Research Centre, UCD Earth Institute and School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Tilman Floehr
- everwave GmbH, Strüverweg 116, 52070 Aachen, Germany
| | - Andreas Jupke
- Fluid Process Engineering, Aachen Process Technology (AVT), RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany
| | - Jürgen Klankermayer
- Institute of Technical and Macromolecular Chemistry (ITMC), RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
| | - Luo Liu
- College of Life Science and Technology (CLST), Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Chaoyang District, Beijing, 100029 PR China
| | - Victor de Lorenzo
- Interdisciplinary Platform for Sustainable Plastics Towards a Circular Economy-Spanish National Research Council (SusPlast-CSIC), Biological Research Center (CIB-CSIC), 28040 Madrid, Spain
| | - Tanja Narancic
- BiOrbic Bioeconomy SFI Research Centre, UCD Earth Institute and School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Juan Nogales
- Interdisciplinary Platform for Sustainable Plastics Towards a Circular Economy-Spanish National Research Council (SusPlast-CSIC), Biological Research Center (CIB-CSIC), 28040 Madrid, Spain
| | - Rémi Perrin
- SOPREMA, Direction R&D, 14 Rue Saint Nazaire, 67100 Strasbourg, France
| | - Eric Pollet
- BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
| | - Auxiliadora Prieto
- Interdisciplinary Platform for Sustainable Plastics Towards a Circular Economy-Spanish National Research Council (SusPlast-CSIC), Biological Research Center (CIB-CSIC), 28040 Madrid, Spain
| | - William Casey
- Bioplastech Ltd., Nova UCD, Belfield Innovation Park, University College Dublin, Belfield, Dublin 4, Ireland
| | - Thomas Haarmann
- AB Enzymes GmbH, Feldbergstraße 78, 64293 Darmstadt, Germany
| | - Alexandru Sarbu
- SOPREMA, Direction R&D, 14 Rue Saint Nazaire, 67100 Strasbourg, France
| | - Ulrich Schwaneberg
- Institute of Biotechnology (BIOTEC), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Fengxue Xin
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Road, Nanjing, 211816 PR China
| | - Weiliang Dong
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Road, Nanjing, 211816 PR China
| | - Jiamin Xing
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering (IPE), Chinese Academy of Sciences, 1 North 2nd Street, Zhongguancun, Beijing, 100190 PR China
| | - Guo-Qiang Chen
- School of Life Sciences (SLS), Tsinghua University, Beijing, 100084 PR China
| | - Tianwei Tan
- College of Life Science and Technology (CLST), Beijing University of Chemical Technology, Beisanhuan EastRoad 15, Chaoyang District, Beijing, 100029 PR China
| | - Min Jiang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Road, Nanjing, 211816 PR China
| | - Lars M. Blank
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
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Li J, Li S, Liu S, Wei C, Yan L, Ding T, Linhardt RJ, Liu D, Ye X, Chen S. Pectic oligosaccharides hydrolyzed from citrus canning processing water by Fenton reaction and their antiproliferation potentials. Int J Biol Macromol 2018; 124:1025-1032. [PMID: 30465847 DOI: 10.1016/j.ijbiomac.2018.11.166] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/11/2018] [Accepted: 11/17/2018] [Indexed: 02/02/2023]
Abstract
Citrus canning processing water contains a valuable and renewable source of biopolymers and bioactive compounds including pectic polysaccharides. Upgrading these processing wastes can not only alleviate environmental pollution but also add value to the commodity's production. In a previous study we recovered pectic polysaccharides from citrus canning processing water. In the present study, pectic polysaccharides recycled from citrus canning processing water was depolymerized by an optimized Fenton system. The hydrolyzate was fractionated via size-exclusion chromatography into six fractions: 500 Da < LMP1 < 3 kDa; 3 kDa < LMP2 < 5 kDa; 5 kDa < LMP3 < 12 kDa; 12 kDa < LMP4 < 25 kDa; 25 kDa < LMP5 < 100 kDa and LMP6 > 10 wDa. Structure analyses showed that LMP1 were homogalacturonans-enriched non-esterified polysaccharides. While LMP2 contained both HG and rhamnogalacturonan-I (RG-I). Further antitumor assay showed that in comparison with the native pectic polysaccharide with moderate antitumor activity, both LMP1 and LMP2 possessed significant antitumor activity, while the inhibitory effect of LMP1 was higher than that of LMP2, suggesting that the biological properties of LMPs was influenced by structural characteristics, including molecular weight and monosaccharide composition.
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Affiliation(s)
- Junhui Li
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Shan Li
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Shanshan Liu
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Chaoyang Wei
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Lufeng Yan
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Tian Ding
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Robert J Linhardt
- Center for Biotechnology & Interdisciplinary Studies, Department of Chemistry & Chemical Biology, Rensselaer Polytechnic Institute, Biotechnology Center 4005, Troy, NY 12180, USA
| | - Donghong Liu
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Xingqian Ye
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China
| | - Shiguo Chen
- Zhejiang Key Laboratory for Agro-Food Processing, Department of Food Science and Nutrition, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China.
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5
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Abstract
The microtubule depolymerising kinesin-13, MCAK, is phosphorylated at residue T537 by Cdk1. This is the only known phosphorylation site within MCAK’s motor domain. To understand the impact of phosphorylation by Cdk1 on microtubule depolymerisation activity, we have investigated the molecular mechanism of the phosphomimic mutant T537E. This mutant significantly impairs microtubule depolymerisation activity and when transfected into cells causes metaphase arrest and misaligned chromosomes. We show that the molecular mechanism underlying the reduced depolymerisation activity of this phosphomimic mutant is an inability to recognise the microtubule end. The microtubule-end residence time is reduced relative to wild-type MCAK, whereas the lattice residence time is unchanged by the phosphomimic mutation. Further, the microtubule-end specific stimulation of ADP dissociation, characteristic of MCAK, is abolished by this mutation. Our data shows that T537E is unable to distinguish between the microtubule end and the microtubule lattice.
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Affiliation(s)
- Hannah R Belsham
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Claire T Friel
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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6
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Ustyuzhanina NE, Kulakovskaya EV, Kulakovskaya TV, Menshov VM, Dmitrenok AS, Shashkov AS, Nifantiev NE. Mannan and phosphomannan from Kuraishia capsulata yeast. Carbohydr Polym 2017; 181:624-632. [PMID: 29254015 DOI: 10.1016/j.carbpol.2017.11.103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/25/2017] [Accepted: 11/28/2017] [Indexed: 12/30/2022]
Abstract
Linear mannan and branched phosphomannan were identified as exopolysaccharides produced by Kuraishia capsulata yeast. Their structures were determined using nuclear magnetic resonance spectroscopy. The repeating unit of mannan was found to be a trisaccharide →6)-α-Manp-(1→2)-α-Manp-(1→2)-α-Manp-(1→, while the phosphomannan was shown to be built of β-Manp-(1→2)-α-Manp-(1 disaccharide blocks linked by phosphodiester bonds via C-1 and C-6 of the reducing unit. The production of both polysaccharides was shown to depend on the phosphate concentration in the culture medium. In the absence of phosphate, only mannan was obtained, while an excess of KH2PO4 led to the exclusive production of phosphomannan. Chemical depolymerisation of phosphomannan led to the formation of disaccharide β-Manp-(1→2)-(6-P)-Manp, representing the repeating unit of the hydrolysed polysaccharide. The treatment of the disaccharide with alkaline phosphatase resulted in the formation of disaccharide β-Manp-(1→2)-Manp. The latest products can be transformed into glycosyl donors applicable further in the synthesis of oligosaccharides related to Candida cell wall polysaccharides.
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Affiliation(s)
- Nadezhda E Ustyuzhanina
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia
| | - Ekaterina V Kulakovskaya
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow, 142290, Russia
| | - Tatiana V Kulakovskaya
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow, 142290, Russia
| | - Vladimir M Menshov
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia
| | - Andrey S Dmitrenok
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia
| | - Alexander S Shashkov
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia
| | - Nikolay E Nifantiev
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia.
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Muñoz-Almagro N, Montilla A, Moreno FJ, Villamiel M. Modification of citrus and apple pectin by power ultrasound: Effects of acid and enzymatic treatment. Ultrason Sonochem 2017; 38:807-819. [PMID: 27993542 DOI: 10.1016/j.ultsonch.2016.11.039] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 05/24/2023]
Abstract
Pectin-derived oligosaccharides are emerging as a new generation of functional ingredients with new or improved technological and/or bioactive properties as compared to pectin. This work addresses the impact of power ultrasound (US) on the structure of citrus and apple pectin under different experimental conditions of power, amplitude and pectin concentration in aqueous and acid media, as well as in the presence of a pectinase. Results indicated that depolymerisation of both pectin increased with time and intensity of US in aqueous media and their polydispersity decreased. In general, a higher depolymerisation was observed in pectin treated by US in the presence of nitric and citric acids than in water, and hardly any difference was detected between both types of acids. Most of the assays gave rise to high-methoxylated pectin with a degree of esterification above 50%, pointing out their suitability for potential gelling agents. Finally, US did not have any impact in assisted enzymatic hydrolysis on the degree and/or rate of depolymerisation at low and medium levels of pectin concentration (0.5 and 2%), whereas a higher diversity of pectin fragments was found at 5% which could be indicative of a more controlled depolymerisation. These findings highlight the importance of the selection of appropriate US processing conditions to diversify the applications of modified pectin, as well as the potential of US as a prospective alternative to currently used depolymerisation techniques.
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Affiliation(s)
- Nerea Muñoz-Almagro
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) (CSIC-UAM) CEI (CSIC+UAM), Nicolás Cabrera, 9, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Antonia Montilla
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) (CSIC-UAM) CEI (CSIC+UAM), Nicolás Cabrera, 9, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - F Javier Moreno
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) (CSIC-UAM) CEI (CSIC+UAM), Nicolás Cabrera, 9, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Mar Villamiel
- Instituto de Investigación en Ciencias de la Alimentación (CIAL) (CSIC-UAM) CEI (CSIC+UAM), Nicolás Cabrera, 9, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Abstract
Oxidation of the primary OH groups in cellulose is a pivotal reaction both at lab and industrial scale, leading to the value-added products, i.e. oxidized cellulose which have tremendous applications in medicine, pharmacy and hi-tech industry. Moreover, the introduction of carboxyl moieties creates prerequisites for further cellulose functionalization through covalent attachment or electrostatic interactions, being an essential achievement designed to boost the area of cellulose-based nanomaterials fabrication. Various methods for the cellulose oxidation have been developed in the course of time, aiming the selective conversion of the OH groups. These methods use: nitrogen dioxide in chloroform, alkali metal nitrites and nitrates, strong acids alone or in combination with permanganates or sodium nitrite, ozone, and sodium periodate or lead (IV) tetraacetate. In the case of the last two reagents, cellulose dialdehydes derivatives are formed, which are further oxidized by sodium chlorite or hydrogen peroxide to form dicarboxyl groups. A major improvement in the cellulose oxidation was represented by the introduction of the stable nitroxyl radicals, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). However, a major impediment for the researchers working in this area is related with the severe depolymerisation occurred during the TEMPO-mediated conversion of CH2OH into COOH groups. On the other hand, the cellulose depolymerisation represent the key step, in the general effort of searching for alternative strategies to develop new renewable, carbon-neutral energy sources. In this connection, exploiting the biomass feed stocks to produce biofuel and other low molecular organic compounds, involves a high amount of research to improve the overall reaction conditions, limit the energy consumption, and to use benign reagents. This work is therefore focused on the parallelism between these two apparently antagonist processes involving cellulose, building a necessary bridge between them, thinking how the reported drawbacks of the TEMPO-mediated oxidation of cellulose are heading towards to the biomass valorisation, presenting why the apparently undesired side reactions could be turned into beneficial processes if they are correlated with the existing achievements of particular significance in the field of cellulose conversion into small organic compounds, aiming the general goal of pursuing for alternatives to replace the petroleum-based products in human life.
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Affiliation(s)
- Sergiu Coseri
- "Petru Poni" Institute of Macromolecular Chemistry of Romanian Academy, 41A Grigore Ghica Voda Alley, Iasi 700487, Romania.
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Frank L, Nebesářová J, Vancová M, Paták A, Müllerová I. Imaging of tissue sections with very slow electrons. Ultramicroscopy 2014; 148:146-150. [PMID: 25461591 DOI: 10.1016/j.ultramic.2014.10.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 08/29/2014] [Accepted: 10/13/2014] [Indexed: 11/25/2022]
Abstract
The examination of thin sections of tissues with electron microscopes is an indispensable tool. Being composed of light elements, samples of living matter illuminated with electrons at the usual high energies of tens or even hundreds of kiloelectronvolts provide very low image contrasts in transmission or scanning transmission electron microscopes. Therefore, heavy metal salts are added to the specimen during preparation procedures (post-fixation with osmium tetroxide or staining). However, these procedures can modify or obscure the ultrastructural details of cells. Here we show that the energy of electrons used for the scanned transmission imaging of tissue sections can be reduced to mere hundreds or even tens of electronvolts and can produce extremely high contrast even for samples free of any metal salts. We found that when biasing a sufficiently thin tissue section sample to a high negative potential in a scanning transmission electron microscope, thereby reducing the energy of the electrons landing on the sample, and collecting the transmitted electrons with a grounded detector, we obtain a high contrast revealing structure details not enhanced by heavy atoms. Moreover, bombardment with slow electrons sensitively depolymerises the resin in which the tissue is embedded, thereby enhancing the transmitted signal with no observable loss of structure details. The use of low-energy electrons requires ultrathin sections of a thickness of less than 10nm, but their preparation is now possible. Ultralow energy STEM provides a tool enabling the observation of very thin biological samples without any staining. This method should also be advantageous for examination of 2D crystals, thin films of polymers, polymer blends, etc.
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Affiliation(s)
- L Frank
- Institute of Scientific Instruments AS CR, v.v.i., Královopolská 147, 61264 Brno, Czech Republic.
| | - J Nebesářová
- Biology Centre AS CR, v.v.i., Branišovská 31, 37005 České Budějovice, Czech Republic
| | - M Vancová
- Biology Centre AS CR, v.v.i., Branišovská 31, 37005 České Budějovice, Czech Republic
| | - A Paták
- Institute of Scientific Instruments AS CR, v.v.i., Královopolská 147, 61264 Brno, Czech Republic
| | - I Müllerová
- Institute of Scientific Instruments AS CR, v.v.i., Královopolská 147, 61264 Brno, Czech Republic
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Ou K, Gu L. Depolymerisation optimisation of cranberry procyanidins and transport of resultant oligomers on monolayers of human intestinal epithelial Caco-2 cells. Food Chem 2014; 167:45-51. [PMID: 25148958 DOI: 10.1016/j.foodchem.2014.06.092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 05/06/2014] [Accepted: 06/10/2014] [Indexed: 10/25/2022]
Abstract
Procyanidins in cranberries are predominantly polymers (>85%). The objective of this study was to optimise the depolymerisation of polymers and to investigate the absorption of resultant oligomers on Caco-2 cell monolayers. Depolymerisation conditions were optimised using response surface methodology. Depolymerisation, with or without added epicatechin, yielded 644 μg and 202 μg of oligomers (monomer through tetramers) per mg of partially purified polymers (PP), respectively. Oligomers (yielded from both methods) were transported through Caco-2 cell monolayer despite absorption rates being low. With the aid of response surface methodology, the optimum depolymerisation conditions were determined to be 60°C, 0.1M HCl in methanol and 3h without added epicatechin. The predicted maximum yield was 364 μg oligomers per mg of PP. The optimum depolymerisation condition with added epicatechin shared the same temperature, acid concentration and reaction time, in addition to an epicatechin/PP mass ratio of 2.19. Its predicted maximum oligomer yield was 1,089 μg/mg. The predicted yields were verified by experimental data.
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Affiliation(s)
- Keqin Ou
- Food Science and Human Nutrition Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, United States
| | - Liwei Gu
- Food Science and Human Nutrition Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, United States.
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Chuck CJ, Parker HJ, Jenkins RW, Donnelly J. Renewable biofuel additives from the ozonolysis of lignin. Bioresour Technol 2013; 143:549-554. [PMID: 23831897 DOI: 10.1016/j.biortech.2013.06.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/12/2013] [Accepted: 06/14/2013] [Indexed: 06/02/2023]
Abstract
In this investigation ozonolysis in the presence of ethanol was used to depolymerise lignin, resulting in a low conversion of oxygenated aromatics over short reaction times, or a range of saturated esters over 24 h. Short chain oxygenates can be used as fuel additives, displacing a percentage of a hydrocarbon fuel while leading to improvement in some of the fuel properties. The utility of the resulting bio-oils was therefore assessed by blending with a range of fuels. Guaiacol, a potential antioxidant, was formed over short reaction times and was found to be completely miscible with low-sulphur petrol (ULSP), diesel, aviation kerosene and rapeseed methyl ester. The mainly aliphatic proportion of the bio-oil produced over 24 h could be blended with the fuels replacing a maximum of 12-17 wt.% of the hydrocarbon fuel.
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Affiliation(s)
- Christopher J Chuck
- Centre for Sustainable Chemical Technologies, Department of Chemical Engineering, University of Bath, Bath BA2 7AY, UK.
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