Optimization of Ca2+ content in alginate hydrogel injected in myocardium

The spontaneous uptake of Ca2+-ions is a unique property of alginate hydrogels, which, along with their high biocompatibility, disintegration (approximately within 2 weeks), and morphological similarity to heart tissue, makes them attractive as scaffolding materials in therapies in infarct myocardium. To shed light on the aforementioned ability, thorough theoretical calculations were carried out with the density functional theory (DFT) method. The influence of Ca-content omicron n the molecular structure and the thermodynamic stability of the alginate hydrogel was determined; what is more, these results effectively interpreted the experimental findings, as well. This analysis suggests that in Ca-free or Ca-deficient alginates spontaneous Ca2+ cations uptake can occur from the biological environment and develop, via chelation reaction, a well-formed and thermodynamically stable hydrogel in situ inside the tissue. The highest degree of cross linking results in viscosity peak. Nevertheless, further increase of Ca-content in alginate structure beyond this peak results in products with poorer thermodynamic stability. Structural optimization DFT calculations revealed that the destabilization of the Ca-rich alginate hydrogels is attributed to changes of the alginate chain molecule, which are relaxation, weakening, and eventually total collapse of the bond between the units of the alginate chain. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 223-231, 2019.