Surface Chemical and Morphological Analysis of Chitosan/1,3-β-d-Glucan Polysaccharide Films Cross-Linked at 90 °C

Abstract

The cross-linking temperature of polymers may affect the surface characteristics and molecular arrangement, which are responsible for their mechanical and physico-chemical properties. The aim of this research was to determine and explain in detail the mechanism of unit interlinkage of two-component chitosan/1,3-β-d-glucan matrices gelled at 90 °C. This required identifying functional groups interacting with each other and assessing surface topography providing material chemical composition. For this purpose, various spectroscopic and microscopic approaches, such as attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), were applied. The results indicate the involvement mainly of the C-C and C-H groups and C=O⋯HN moieties in the process of biomaterial polymerization. Strong chemical interactions and ionocovalent bonds between the N-glucosamine moieties of chitosan and 1,3-β-d-glucan units were demonstrated, which was also reflected in the uniform surface of the sample without segregation. These unique properties, hybrid character and proper cell response may imply the potential application of studied biomaterial as biocompatible scaffolds used in regenerative medicine, especially in bone restoration and/or wound healing.

FT-IR Method Limitations for β-Glucan Analysis

“…In P. pastoris , the yeast cell wall structure as well as the β-glucan structure might be slightly different from other analyzed yeasts regarding higher chitin content or β-1,4-glucan presence in its structure [ 24 ]. Although we suggest that P. pastoris also exhibits β-1,3/1,6-glucan structure, compared to other yeasts, the band at 1027 cm −1 is stronger and could be attributed to β-1,4-glycosidic bond, which might indicate relatively higher chitin or β-1,4-glucan content in the cell wall of P. pastoris [ 12 , 33 ]. This could represent species-specific structural differences compared to other yeasts.…”

“…The small shoulder located at 1650 cm −1 has lower intensity after treatment with organic solvents in all samples compared to autolysis. Vibration of proteins at 1587 cm −1 and 1624 cm −1 [ 17 , 48 , 49 ] indicate traces of proteins, as well as bands at 1650, 1517 and 1312 cm −1 , which represent various protein secondary structures [ 33 , 50 ]. The band between 1600–1500 cm −1 in hot water-extracted β-glucans from C. guilliermondii and C. lusitaniae possess a peak at 1517 cm −1 , which could possibly indicate higher protein content compared to β-glucans from other yeasts [ 25 , 33 ].…”

“…However, β-glucan analysis in solution requires its degradation, which may affect the results. Fortunately, both FT-IR and NMR as well as Raman spectroscopy and X-ray crystallography allow the use of solid samples [ 28 , 30 , 33 ]. Together with hot water extraction, this allows the analysis of the preserved native structure of the β-glucans [ 24 , 33 ].…”

“…Fortunately, both FT-IR and NMR as well as Raman spectroscopy and X-ray crystallography allow the use of solid samples [ 28 , 30 , 33 ]. Together with hot water extraction, this allows the analysis of the preserved native structure of the β-glucans [ 24 , 33 ]. FT-IR spectroscopy is a powerful technique which has been used to analyze glucans from yeasts and is suitable to analyze the position and anomeric configuration of glycosidic linkages in high molecular weight glucans isolated from raw materials, thus allowing researchers to evaluate structural differences of these molecules [ 31 , 34 ].…”

Spectroscopic analysis of mushrooms by surface-enhanced Raman scattering (SERS)

“…[44]. However, we cannot exclude that these bands are related to the polysaccharides existing in the fungal cell wall as reported by Gieroba et al (2022) [45]. These two different groups will henceforth be referred to as A-group and B-group, respectively.…”