Production and analysis of alginate oligosaccharides and their effect on the physical properties of gellan gum

Abstract

Alginate oligosaccharides, in particular G blocks, have recently been shown to have some interesting biomedical applications. In this work G-blocks were extracted from sodium alginate salt and was characterised by ¹H-NMR, ¹³C-NMR (nuclear magnetic resonance). In addition, molecular weight and polymerization degree for this compound were measured by using size exclusion chromatography- multiangle laser light scattering (SEC-MALLS). The prepared G blocks were added to several types of polysaccharides including gellan gum and two kinds of alginates containing different amount of G residues. It was found that G-block addition seemed to be more effective on gellan gum viscosity than on alginates; gellan gum viscosity increase with adding 2.0% w/v of G-block then G-block addition (3.3%w/v) lead to decrease the viscosity. Rheological measurements of viscoelastic properties of hydrogels containing increasing concentrations of G blocks were also performed. The elastic modulus of gellan gum gel hugely decreased with adding 0.6%w/v of G-block then increase gradually with 2.0%w/v G-block. These results highlight the potential of G block oligosaccharides in modifying and controlling the mechanical properties of other polysaccharides which could have applications in developing drug delivery systems and biomaterials.