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Malinkina ON, Shmakov SL, Shipovskaya AB. Structure, the energy, sorption and biological properties of chiral salts of chitosan with l- and d-ascorbic acid. Int J Biol Macromol 2024; 257:128731. [PMID: 38101672 DOI: 10.1016/j.ijbiomac.2023.128731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 11/18/2023] [Accepted: 12/08/2023] [Indexed: 12/17/2023]
Abstract
The influence of l- and d-ascorbic acid diastereomers on the structure, supramolecular ordering, energy, sorption and biological properties of heterochiral (D-L) and homochiral (D-D) salt complexes of chitosan (d-glucan)-acid was studied. The thermal effect of dissolving chitosan in l-ascorbic acid and the protonation degree of (D-L)-salts were lower than those in the medium of the d-isomer. Homochiral (D-D) salts, in contrast to heterochiral (D-L) ones, are distinguished by a more developed system of intermolecular and intramolecular contacts, a more ordered and equilibrium supramolecular organization of macrochains, a higher crystallinity degree, and a smaller amount of crystallization water. The sorption isotherms of chiral salts were approximated by the thermal equation of sorption and the superposition of the Langmuir and Flory-Huggins isotherms. Significant differences were found in the limiting value and energy of sorption, the constant of adsorption equilibrium, the limiting sorption capacity of the localized mode of water, and the Gibbs mixing energy. Biotesting on non-vascular (Scenedesmus quadricauda) and vascular eukaryotes (Linum usitatissimum) revealed the growth-stimulating effect of the D-D salts. The obtained results confirm our hypothesis of the homochiral salt complexes d-glucan-d-ascorbic acid best corresponding to the principles of the functional organization of biological objects.
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Affiliation(s)
- Olga N Malinkina
- Institute of Chemistry, Saratov State University, Astrakhanskaya 83, Saratov 410012, Russian Federation.
| | - Sergei L Shmakov
- Institute of Chemistry, Saratov State University, Astrakhanskaya 83, Saratov 410012, Russian Federation
| | - Anna B Shipovskaya
- Institute of Chemistry, Saratov State University, Astrakhanskaya 83, Saratov 410012, Russian Federation
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Estevez-Areco S, Macchi C, Guz L, Goyanes S, Somoza A. Evolution of the free volume during water desorption in thermoplastic starch/citric acid films: In situ positron annihilation studies. Carbohydr Polym 2023; 310:120739. [PMID: 36925254 DOI: 10.1016/j.carbpol.2023.120739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 02/07/2023] [Accepted: 02/20/2023] [Indexed: 02/25/2023]
Abstract
The effect of citric acid (CA) concentration and water content on the free hole volume of thermoplastic cassava starch films (TPS) was studied. To this aim, continuous in situ positron annihilation lifetime spectroscopy measurements were performed at fixed moisture content and during water desorption. The results show that the increase in CA concentration leads to wider free hole volume distributions with lower mean values. During water desorption, the mean values and width of such distributions systematically decrease with the exposure time, and the evolution of the hole volumes was well-described using the Kohlrausch-Williams-Watts function. The water vapour permeability was significantly higher in films incorporating 5 % (w/w) of CA, in line with the more open network of this material that was revealed in the hole volumes distribution. The Young's modulus of all the developed films increased significantly after partial water desorption, which was attributed to the plasticizer loss reflected in a decrease in the mean hole volume value (between 4 % and 13 %). This work evidences that the control and report of the relative humidity are essential when testing TPS-based films, as their nanostructures are strongly dependent on external conditions.
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Affiliation(s)
- Santiago Estevez-Areco
- Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Facultad de Ciencias Exactas, Instituto de Física de Materiales Tandil (IFIMAT), Grupo Positrones "Prof. Alfredo Dupasquier", Pinto 399, 7000 Tandil, Buenos Aires, Argentina; CIFICEN, UNCPBA-CICPBA-CONICET, Tandil, Buenos Aires, Argentina.
| | - Carlos Macchi
- Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Facultad de Ciencias Exactas, Instituto de Física de Materiales Tandil (IFIMAT), Grupo Positrones "Prof. Alfredo Dupasquier", Pinto 399, 7000 Tandil, Buenos Aires, Argentina; CIFICEN, UNCPBA-CICPBA-CONICET, Tandil, Buenos Aires, Argentina.
| | - Lucas Guz
- Instituto de Investigación e Ingeniería Ambiental (IIIA), CONICET, Universidad Nacional de San Martín, (3iA), Campus Miguelete, 25 de mayo y Francia (1650), San Martín, Buenos Aires, Argentina.
| | - Silvia Goyanes
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, Laboratorio de Polímeros y Materiales Compuestos (LP&MC), Ciudad Universitaria (C1428EGA), Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Física de Buenos Aires (IFIBA), Ciudad Universitaria (C1428EGA), Ciudad Autónoma de Buenos Aires, Argentina.
| | - Alberto Somoza
- Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Facultad de Ciencias Exactas, Instituto de Física de Materiales Tandil (IFIMAT), Grupo Positrones "Prof. Alfredo Dupasquier", Pinto 399, 7000 Tandil, Buenos Aires, Argentina; CIFICEN, UNCPBA-CICPBA-CONICET, Tandil, Buenos Aires, Argentina.
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