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Abstract

Despite its unique properties (biocompatibility and nontoxicity), chitin itself has limited application. Chitin is completely insoluble in most organic or inorganic solvents what can be beneficial when chitin is investigated as a support for chromatography or enzyme immobilization. These applications require the particles to have an extensive outer surface with a large number of reactive ligands. The increase in specific surface area of chitin particles can be performed by dissolution in ionic liquid and precipitation with water. To increase the number of reactive ligands (amine groups), deacetylation of the surface of chitin particles is necessary. The deacetylation process can be carried out by an enzymatic process with the enzyme, chitin deacetylase. In our investigation, 21 ionic liquids were used for chitin particle structure modification followed by enzymatic deacetylation. Results proved positive effect of modifications with ionic liquid on enzymatic deacetylation of the chitin surface with chitin deacetylase. For 12 samples the deacetylation gave an increase in number of active ligands in comparison to natural chitin. The best results were observed for [Bmim][Br], [Emim][Cl] and [MPpip][Ac]. That could be correlated with an increase in outer surface area by increasing porosity of particles or by structural changes in chitin particles.
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Authors and Affiliations

Małgorzata M. Jaworska
1
ORCID: ORCID
Dorota Biniaś
2
ORCID: ORCID
Katarzyna Dąbkowska-Susfał
1
ORCID: ORCID
Andrzej Górak
3
ORCID: ORCID

  1. Warsaw University of Technology, Faculty of Chemical and Process Engineering, Warynskiego 1, 00-645 Warsaw, Poland
  2. University of Bielsko-Biała, Faculty of Materials, Civil and Environmental Engineering, Department of Environmental Protection and Engineering, Willowa 2, 43-309 Bielsko-Biała, 9 Poland
  3. Faculty of Process Engineering and Environmental Protection, Lodz Technical University, ul. Wólczanska 213, 93-005 Lodz, Poland
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Abstract

Concentration of Zn, Cu, Cd, Pb and Co have been determined in Antarctic water (South Shetland Islands) and in krill exoskeletons with the help of atomic absorption spectrophotometry. Concentrations of these metals both in sea-water and in krill exoskeleton are in order Zn > Cu > Cd > Ni > Pb > Co. Comparing concentrations of these metals in sea-water to their concentrations in krill exoskeleton, the factors have been calculated giving a list of metals in the order of krill chitin ability, which is Ni > Cu > Zn > Cd > Pb > Co accumulation. The highest accumulation factors for Ni and Cu point out to the special role played by these metals in krill life.

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Authors and Affiliations

Witold Neugebauer
Piotr Bykowski
Ewa Neugebauer
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Abstract

The possibility of producing chitosan by enzymatic deacetylation of chitin has been the subject of numerous investigations over the last twenty years, but to date no satisfactory method has been developed. In this paper the influence of chitin chain conformation and chitin particle crystallinity on the enzymatic deacetylation of chitin is investigated to determine the relative importance of these two factors on the process. It is shown that the high crystallinity of chitin is the main obstacle to converting chitin to chitosan by enzymatic deacetylation.

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Authors and Affiliations

Małgorzata M. Jaworska
George A.F. Roberts
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Abstract

Chitin deacetylase is the only known enzyme which is able to deacetylate N-acetyl-D-glucosamine units in chitin or chitosan chains. As chitin can hardly be dissolved in organic/inorganic solvents, new solvents are still searched. Ionic liquids are promising for that application and for homophase enzymatic deacetylation. The aim of the work was to investigate the influence of selected ionic liquids on activity of chitin deacetylase.

It has been shown that [Amim] ionic liquids increase the activity of chitin deacetylase. The highest activity was observed for [Amim][Cl]. Ionic liquids with shorter (ethyl (C2)) and longer side chain (buthyl (C4)) only insignificantly influenced the activity of the enzyme. All tested ionic liquids with [Br] anion increased the activity of chitin deacetylase while the [Emim] and [Bmim] cation in combination with [Cl] anion inhibited the activity of the enzyme.

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Authors and Affiliations

Izabela Aspras
Małgorzata Kamińska
Kamil Karzyński
Mateusz Kawka
Małgorzata M. Jaworska

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