Plenary Lecture

Nitroxides in Cotton and Cellulose Physicochemistry and Technology. 40 Years of History

Professor Likhtenshtein Gertz I.
Ben-Gurion University of the Negev, Beer Sheva, Israel
&
Institute of Problems of Chemical Physics, Russian of Academy of Science
Chernogolovka, Moscow region, Russia
E-mail: gertz@bgu.ac.il

Abstract: Since pioneering work [1] nitroxides are widely used in solving a number of challenging problems of structure and functions of cotton fibres and cellulose. Methods of nitroxide spin labelling have been proved to be a powerful tool in this area [2 – 4]. Covalent l modification cotton fibers and cellulose by the labels and the use Electron Spin Resonance (ESR) allow to establish the label location and motion in the labelled samples which in turn is modulated by the polymers local molecular dynamics and its distribution. Data on dependencies of the fibers molecular dynamics on origin, temperature, water and other plasticizing agents, nutrition, period of maturing, virus infection and radiation of seeds have been presented. Combination of ESR experiments and Zhurkov technique has revealed a strong dependence of fibres’ resistance to stress (durability) on microscopic structural defects. In the fibres, the distribution of the molecular dynamics correlation time within 10-4 – 10-9 s temporal range was also established. Employing non-covalently bound nitroxides as spin probes provides a way for studies of effect of humidity on the supramolecular structure of cotton, local polarity and heterogeneous viscosity of two types of unprocessed cotton fibers, cellulose modification by nitroxide-mediated graft polymerization, composites of poly(lactic) acid reinforced with TEMPO-oxidized fibrillated cellulose, photo-induced macromolecular functionalization of cellulose via nitroxide spin trapping, EPR characterization of cellulose triacetate fibers used for enzyme immobilization, and preparation cellulose modified by nitroxides through mechanochemical synthesis. The developed approach, the efficiency of which is demonstrated in this review, can be used in the investigation of molecular dynamics, microstructure polymers and other complex molecular objects.
1. Marupov R, Bobodzhanov P. Kh., Yusupov I. Kh., Frolov E. N.. Likhtenshtein G. I. Study of temperature stability of cotton fibers by spin labeling. Biofizika 24. 519-523 (1979).
2. Likhtenshtein G.I. (1976).Spin Labeling Method in Molecular Biology, N. Y., Wiley Interscience, New York.
3. Likhtenshtein G.I., Yamauchi J, Nakatsuji S, Smirnov A., Tamura R. Nitroxides: Application in Chemistry, Biomedicine, and Materials Science. WILEY-VCH, Weinhem, 2008.
4. Ysupov, I. Kh.; Likhtenshtein G.I. . Study of microstructure and molecular dynamics of cotton and cellulose fibers by methods of physical labels. International Research Journal of Pure and Applied Chemistry 6(3), 105-119 (2015).

Brief Biography of the Speaker: Gertz I. Likhtenshtein received his PhD (1963) and Doctor of Science (1972) degrees at the Semenov Institute of Chemical Physics, Russian academy of Science, Moscow. In 1976 this Institute granted him the Professor title. In 1965 he was appointed on the position of Head of Laboratory of Chemical Physics of Enzyme Catalysis. In 1992 Likhtenshtein moved to the Department of Chemistry, the Ben-Gurion University of Negev (Israel) on the full Professor position, was in charge of the Laboratory of Chemical Biophysics and has been emerited in 2003. From 2016 Likhtenshtein is an adviser to the director of Institute of Problems of Chemical Physics, Russian Academy of Science, Chernogolovka, Moscow region. Among his awards are the Medal of the Exhibition of Economic Achievement (1968), the USSR State Price for pioneering research on spin labeling in molecular biology (1977), the Diploma of Discovery USSR for works on nitrogen fixation (1979), the Diploma of the Israel Chemical Society (2000) and the V. V. Voevodsky International Price for Chemical Physics (2007), and the Academician N. M. Emanuel Golden Medal for Chemical Biophyscs (2015). He was a member of the International ESR Society, the American Biophysical Society, the Israel Chemical Society and the Israel ESR Society. At present his main scientific interests focus on mechanism of the light energy conversion and on novel methods of immunoassay, NO and antioxidants analysis. Likhtenshtein authored 11 scientific books and about 390 papers.

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