Obtaining and Derivatization of Chitosan on The Basis of Insects
Khabibullaeva Nozima and Khaitbaev Alisher*
Chemistry faculty, National University of Uzbekistan, Uzbekistan
Submission: January 20, 2023; Published: February 17, 2023
*Corresponding author: Khaitbaev Alisher, Department of Chemistry, National University of Uzbekistan, Tashkent 100174, Uzbekistan
How to cite this article: Khabibullaeva Nozima and Khaitbaev Alisher. Obtaining and Derivatization of Chitosan on The Basis of Insects. Curr Trends Fashion Technol Textile Eng. 2023; 8(1): 555728. DOI: 10.19080/CTFTTE.2023.08.555728
Abstract
Recently, there has been a great deal of attention around the world to finding new raw materials of chitosan, which exhibits high biological activity and to synthesize its new derivatives. During our research, we aimed to obtain chitosan from various local wasps (Apis mellifera, Polistes Chinensis, Vespa Orientalis), to study its structure using physicochemical methods: IR and NMR spectroscopy, GPC, XRD, and synthesis of water-soluble products.
Keywords: α-Chitin; Chitosan; Crystal System; N-alkyl; N–acyl derivatives
Abbreviations: IR: Infrared; NMR: Nuclear Magnetic Resonance; GPC: Gel-permeation Chromatography; XRD: X-ray Diffraction; CI: Crystalline Index, DDA: Degree of Deacetylation
Introduction
Chitin and its important derivative chitosan is the linear polysaccharide, which consists of the β-(1→4) linked N-Acetyl-D-glucosamine (Glc-NAc) and D-glucosamine (Glc-N) units. In nature, chitin occurs in a variety of organisms, including infusoria, amoebae, chrysophytes, some algae, fungi, crustaceans, worms, insects, mollusks, and in the cell walls of fungi and microorganisms (bacteria) [1]. Chitin has 3 polymorph forms: α-, β- and γ- chitin. In these forms, chitin microfibrils are oriented differently and are differentiated using IR and NMR spectroscopy and X-ray diffractometry [2]. In the solid-state, chitin chains are bound with hydrogen bonds that affect many of its physicochemical properties. Chitosan is obtained through alkaline hydrolysis of acetamide groups of chitin. Chitin and chitosan are widely used in medicine, cosmetology, agriculture, textile, paper industry, genetic engineering, pharmacology, and other fields because of their many important biological activities. Chitosan is obtained from crustaceans on an industrial scale. Recently, great attention has been paid to the separation of chitin and chitosan from insects and their use as an alternative raw material for chitin [3,4].
Chitosan is soluble in dilute organic solvents pH <6.5 because the pKa value of N-amino groups is 6.5. The solubility of chitosan in aqueous acid solutions with a pH of ≥ 6.5 leads to limitations in application fields (cosmetology, food, and biomedicine). This is because the use of chemicals in biological applications requires the material to be treated at a neutral pH. Numerous studies have been conducted to increase the water solubility of chitosan and thereby expand its application. Improving the water solubility of the polymer involves the chemical modification of N-amino functional groups. As a result, water-soluble N-substituted products are obtained. N-substitution reactions include: N-alkylation, N-acetylation, N-hydroxylation and etc. [5].
In this research, we obtained initially chitin from local raw materials (Apis melliefra, Polistes Chinensis, Vespa orientalis) and chitosan by deacetylation of chitin. After that, we studied its physicochemical properties. In the next step, we synthesized N-alkyl and N-acyl derivatives based on low molecular weight chitosan and analyzed their structure.
Conclusion
During our research, chitosan with a high yield (5-6%) based on Apis mellifera was obtained compared to other wasps, and its structure was analyzed using IR, 1H and 13C NMR spectroscopy methods. IR spectra were analyzed to determine the polymorph form of the extracted chitin, it was observed that a split signal was formed in the absorption region belonging to the amide I band, which indicates that α-chitin was obtained. When the molecular weight of chitosan was analyzed using GPC, an increase or decrease in molecular weight depending on DDA was determined. Analysis using the XRD method revealed that a crystal system with a tetragonal structure of chitosan was obtained with a CI = 31.65%. Therefore, N-alkyl and N-acyl derivatives of chitosan were synthesized with some cyclic and aliphatic aldehydes and acid anhydrides, and their structures were analyzed.
Acknowledgment
We would like to express our gratitude to Boymirzaev A., Professor of the Department of Chemical Technology of the Namangan Institute of Engineering and Technology, who closely assisted in determining the molecular mass of the chitosan sample by means of gel-permeation chromatography; Bobakulov Kh., Department of Physical Research Methods of the Institute of the Chemistry of Plant Substances AS RUz who closely assisted in the analysis of the chitosan sample by means of NMR spectroscopy. Also, thank Eshchanov Kh. for his contribution to XRD data analysis.
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