The model pH-controlled delivery system based on gelatin-tannin hydrogels containing ferrous ascorbate: iron release in vitro.

Hydrogels became an essential class among all biomaterials. Specialized biomaterials are highly appreciated in the field of biomedical applications. One of problem in wound management is a local deficiency of microelements related to extensive wound lesions. The significant absence of an elemental iron in human body leads to serious consequences and prolongation of treatment. The synthesis of gelatin-tannin hydrogels with ion delivery function is proposed in this study. The ability to release ions in low acidity solution is a sphere of great interest. pH downing in wound cavity usually concerns with contamination of some bacterial cultures. pH-controlled delivery of iron in buffer solutions (рН=5.5/6.4/7.4) was considered for these hydrogels. The kinetic of iron release was determined by visible spectroscopy. Theoretical models were applied to describe process of ion delivery. The structure of materials was examined by IR-spectroscopy and demonstrated incorporation of ferrous ascorbate in hydrogel matrix. Thermal analysis was used to pointed the key differences in thermal behavior by isoconversional methods (Flynn-Wall-Ozawa/Kissinger-Akahira-Sunose). Mechanical characteristics of materials were studied. The effect of iron ascorbate on polymer network parameters was discussed. Current study showed a possibility of obtaining gelatin-tannin hydrogels for pH-dependent iron delivery. That provides future perspectives to expand the set of releasing microelements for biomedical applications.