Evaluation of chitosan crystallinity: A high-resolution solid-state NMR spectroscopy approach

Author(s)

Facchinatto, William Marcondes ^[1] ; dos Santos, Danilo Martins ^[2] ; Fiamingo, Anderson ^[3] ; Bernardes-Filho, Rubens ^[2] ; Campana-Filho, Sergio Paulo ^[1] ; de Azevedo, Eduardo Ribeiro ^[3] ; Colnago, Luiz Alberto ^[2]

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Inst Chem, Av Trabalhador Sao Carlense 400, Caixa Postal 780, BR-13566590 Sao Carlos, SP - Brazil

^[2] Brazilian Corp Agr Res, Embrapa Instrumentat, Rua 15 Novembro 1452, Caixa Postal 741, BR-13560970 Sao Carlos, SP - Brazil

^[3] Univ Sao Paulo, Sao Carlos Inst Phys, Av Trabalhador Sao Carlense 400, Caixa Postal 369, BR-13566590 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Carbohydrate Polymers; v. 250, DEC 15 2020.
• Web of Science Citations: 0

Abstract

We propose a novel approach relied on high-resolution solid-state C-13 NMR spectroscopy to quantify the crystallinity index of chitosans (Ch) prepared with variable average degrees of acetylation ((DA) over bar) from 5% to 60 % and average weight molecular weight ((M ) over bar (w)) ranged in 0.15 x 10(6) g mol(-1) -1.2 x 10(6) g mol(-1). The Dipolar Chemical Shift Correlation (DIPSHIFT) curve of the C(6)OH segment revealed increased mobility dynamic, which induced different distribution from trans-to-gauche conformations in relation to C(4). Indeed, H-1-C-13 Heteronuclear Correlation (2D HETCOR) showed that distinguished C4 chemical shifts correlates with the same aliphatic protons. The short-range ordering can be assigned to C4/C6 signals on C-13 CPMAS and, for our case, the deconvolution procedure between disordered and ordered phases revealed increasing crystallinity with (DA) over bar, as confirmed by SVD multivariate analysis. This work extended the knowledge regarding the use of C-13 CPMAS technique to predict the crystallinity of chitosans without the use of amorphous standards. (AU)

• FAPESP's process: 17/24465-3 - NMR methods for plant cell wall characterization: development and applications to second generation biofuel technologies
• Grantee: Eduardo Ribeiro de Azevedo
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Regular Program Grants
• FAPESP's process: 16/20970-2 - Study of chitosan and hydrophilic derivatives by time domain NMR
• Grantee: William Marcondes Facchinatto
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 17/20973-4 - Coaxial electrospun nanofibers based on chitosan for controlled release of antibiotics and periodontic lesion treatment
• Grantee: Danilo Martins dos Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 16/09720-4 - Use of membrane models to evaluate the biodegradability of chitosan
• Grantee: Anderson Fiamingo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/13656-8 - Development and application of nuclear magnetic resonance in products and agricultural processes
• Grantee: Luiz Alberto Colnago
• Support Opportunities: Regular Research Grants