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Katan T, Kargl R, Mohan T, Steindorfer T, Mozetič M, Kovač J, Stana Kleinschek K. Solid Phase Peptide Synthesis on Chitosan Thin Films. Biomacromolecules 2022; 23:731-742. [PMID: 35023341 PMCID: PMC8924862 DOI: 10.1021/acs.biomac.1c01155] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Stable chitosan thin
films can be promising substrates for creating
nanometric peptide-bound polyglucosamine layers. Those are of scientific
interest since they can have certain structural similarities to bacterial
peptidoglycans. Such films were deposited by spin coating from chitosan
solutions and modified by acetylation and N-protected
amino acids. The masses of deposited materials and their stability
in aqueous solutions at different pH values and water interaction
were determined with a quartz crystal microbalance with dissipation
(QCM-D). The evolution of the surface composition was followed by
X-ray photoelectron (XPS) and attenuated total reflectance infrared
(ATR-IR) spectroscopy. Morphological changes were measured by atomic
force microscopy (AFM), while the surface wettability was monitored
by by static water contact angle measurements. The combination of
the characterization techniques enabled an insight into the surface
chemistry for each treatment step and confirmed the acetylation and
coupling of N-protected glycine peptides. The developed
procedures are seen as first steps toward preparing thin layers of
acetylated chitin, potentially imitating the nanometric peptide substituted
glycan layers found in bacterial cell walls.
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Affiliation(s)
- Tadeja Katan
- Institute of Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Rupert Kargl
- Institute of Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Tamilselvan Mohan
- Institute of Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Tobias Steindorfer
- Institute of Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Miran Mozetič
- Department of Surface Engineering, Jožef Stefan Institute (IJS), Jamova 39, 1000 Ljubljana, Slovenia
| | - Janez Kovač
- Department of Surface Engineering, Jožef Stefan Institute (IJS), Jamova 39, 1000 Ljubljana, Slovenia
| | - Karin Stana Kleinschek
- Institute of Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
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Demir I, Blockx J, Dague E, Guiraud P, Thielemans W, Muylaert K, Formosa-Dague C. Nanoscale Evidence Unravels Microalgae Flocculation Mechanism Induced by Chitosan. ACS APPLIED BIO MATERIALS 2020; 3:8446-8459. [PMID: 35019616 DOI: 10.1021/acsabm.0c00772] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Microalgae are a promising resource for biofuel production, although their industrial use is limited by the lack of effective harvesting techniques. Flocculation consists in the aggregation and adhesion of cells into flocs that can be more easily removed from water than individual cells. Although it is an efficient harvesting technique, contamination is a major issue as chemical flocculants are often used. An alternative is to use natural biopolymers flocculants such as chitosan. Chitosan is a biobased nontoxic polymer that has been effectively used to harvest Chlorella vulgaris cells at a pH lower than its pKa (6.5). While the reported flocculation mechanism is said to rely on electrostatic interactions between chitosan and the negative cell surface, no molecular evidence has yet confirmed this mechanism. In this study, we performed force spectroscopy atomic force microscopy (AFM) experiments to probe the interactions between C. vulgaris cells and chitosan at the molecular scale to decipher its flocculation mechanism. Our results showed that at pH 6, chitosan interacts with C. vulgaris cell wall through biological interactions rather than electrostatic interactions. These observations were confirmed by comparing the data with cationically modified cellulose nanocrystals, for which the flocculation mechanism, relying on an electrostatic patch mechanism, has already been described for C. vulgaris. Further AFM experiments also showed that a different mechanism was at play at higher pH, based on chitosan precipitation. Thus, this AFM-based approach highlights the complexity of chitosan-induced flocculation mechanisms for C. vulgaris.
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Affiliation(s)
- Irem Demir
- TBI, Université de Toulouse, INSA, INRAE, CNRS, 31400 Toulouse, France.,LAAS, Université de Toulouse, CNRS, 31400 Toulouse, France
| | - Jonas Blockx
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, 8500 Kortrijk, Belgium.,Laboratory for Aquatic Biology, KU Leuven, Campus Kulak Kortrijk, 8500 Kortrijk, Belgium
| | - Etienne Dague
- LAAS, Université de Toulouse, CNRS, 31400 Toulouse, France.,Fédération de Recherche FERMAT, CNRS, 31000 Toulouse, France
| | - Pascal Guiraud
- TBI, Université de Toulouse, INSA, INRAE, CNRS, 31400 Toulouse, France.,Fédération de Recherche FERMAT, CNRS, 31000 Toulouse, France
| | - Wim Thielemans
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, 8500 Kortrijk, Belgium
| | - Koenraad Muylaert
- Laboratory for Aquatic Biology, KU Leuven, Campus Kulak Kortrijk, 8500 Kortrijk, Belgium
| | - Cécile Formosa-Dague
- TBI, Université de Toulouse, INSA, INRAE, CNRS, 31400 Toulouse, France.,Fédération de Recherche FERMAT, CNRS, 31000 Toulouse, France
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Carapeto AP, Ferraria AM, do Rego AMB. Unraveling the reaction mechanism of silver ions reduction by chitosan from so far neglected spectroscopic features. Carbohydr Polym 2017; 174:601-609. [DOI: 10.1016/j.carbpol.2017.06.100] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/08/2017] [Accepted: 06/26/2017] [Indexed: 10/19/2022]
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