Ca(ii) and Ce(iii) homogeneous alginate hydrogels from the parent alginic acid precursor: a structural study

Alginate hydrogels are suitable for the encapsulation of biomolecules and microorganisms for the building of bioactive materials. Several alternatives to the conventional alginate formulation are being studied for a broad range of biotechnological applications; among them the crosslinking of alginate by lanthanide cations, Ln(iii), envisages expanded biomedical applications. The performance of these functional materials is highly related to the microstructure of the alginate matrix, which in turn is affected by the conditions of synthesis. In particular, when a diffusing gradient of the crosslinking cation is involved, microstructure inhomogeneities are expected at the macroscopic level. Here we discuss the subtle differences in the microstructure, as assessed by SAXS (Small Angle X-ray Scattering), established in the direction of the gradient of diffusion of Ca(ii) or Ce(iii).