Characterization of carboxymethylated konjac glucomannan for potential application in colon-targeted delivery

Carboxymethylation is a potential way to extend the application of konjac glucomannan (KGM) in the construction of colon-targeted delivery systems through electrostatic interaction-based techniques. Hence, some related properties of carboxymethylated KGM (CMKGM) were characterized as a function of its degree of substitution (DS). Carboxymethylation decreased the molecular weight and viscoelasticity, increased the thermal stability and water solubility of KGM in a DS-dependent manner, but did not destroy the sensitivity of solution viscosity to temperature variation. The gelation ability of the CMKGMs was greatly weakened and the hardness of their gels was greatly impaired. The CMKGMs carried negative charges with zeta potentials proportional to their DSs, but still maintained similar resistance to proteolytic enzymes and susceptibility to β-mannanase with the native KGM. Hence, the CMKGMs are potential in the construction of colon-targeted and enzyme-triggered delivery systems through layer-by-layer assembly, complex coacervation, and other similar techniques.