Cellulose-pectin composite hydrogels: Intermolecular interactions and material properties depend on order of assembly

• Published in: Carbohydrate polymers 2017-04, Vol.162, p.71-81
• Main Authors: Lopez-Sanchez, Patricia, Martinez-Sanz, Marta, Bonilla, Mauricio R., Wang, Dongjie, Gilbert, Elliot P., Stokes, Jason. R., Gidley, Michael. J.
• Format: Article
• Language: English
• Subjects: Cellulose; Mechanics; Pectin; SANS; SAXS; XRD
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.01.049

•Cellulose-pectin-calcium gels were produced varying order of assembly and pectin DE.•Cellulose-pectin interactions occurred only when pectin was present during cellulose synthesis.•Order of polysaccharide assembly impacted hydrogels microstructure and mechanical properties.•The contribution to mechanical and diffusion properties depended on pectin DE.•These results highlight the multiple roles that pectin might have in cell wall mechanics. Plant cell walls have a unique combination of strength and flexibility however, further investigations are required to understand how those properties arise from the assembly of the relevant biopolymers. Recent studies indicate that Ca2+-pectates can act as load-bearing components in cell walls. To investigate this proposed role of pectins, bioinspired wall models were synthesised based on bacterial cellulose containing pectin-calcium gels by varying the order of assembly of cellulose/pectin networks, pectin degree of methylesterification and calcium concentration. Hydrogels in which pectin-calcium assembly occurred prior to cellulose synthesis showed evidence for direct cellulose/pectin interactions from small-angle scattering (SAXS and SANS), had the densest networks and the lowest normal stress. The strength of the pectin-calcium gel affected cellulose structure, crystallinity and material properties. The results highlight the importance of the order of assembly on the properties of cellulose composite networks and support the role of pectin in the mechanics of cell walls.