The Influence of Oxidant on Gelatin–Tannin Hydrogel Properties and Structure for Potential Biomedical Application

Abstract

Nowadays, there is a widespread usage of sodium periodate as an oxidant for synthesizing gelatin–tannin hydrogels. The impact of iodine compounds could have a harmful effect on human health. The study focuses on the proposal of alternative oxidizing systems for tannin oxidation. Gelatin–tannin hydrogels were obtained based on the usage of H2O2/DMSO/KMnO4/KIO4 oxidants and characterized with sorption, thermal (TGA, DTG, DSC), mechanical, FTIR and other methods. The sorption experiments were carried out in a phosphate buffer (pH = 5.8/7.4/9) and distilled water and were investigated with Fick’s law and pseudosecond order equation. The pH dependence of materials in acid media indicates the possibility of further usage as stimuli-responsive systems for drug delivery. Thermal transitions demonstrate the variation of structure with melting (306 ÷ 319 °C) and glass transition temperatures (261 ÷ 301 °C). The activation energy of water evaporation was calculated by isoconversional methods (Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa) ranging from 4 ÷ 18 to 14 ÷ 38 kJ/mole and model-fitting (Coats–Redfern, Kennedy–Clark) methods at 24.7 ÷ 45.3 kJ/mole, indicating the smooth growth of values with extent of conversion. The network parameters of the hydrogels were established by modified Flory–Rehner and rubber elasticity theories, which demonstrated differences in values (5.96 ÷ 21.27·10−3 mol/cm3), suggesting the limitations of theories. The sorption capacity, tensile strength and permeability for water/oxygen indicate that these materials may find their application in field of biomaterials.

Composite Materials Based on Gelatin and Iron Oxide Nanoparticles for MRI Accuracy

“…The peaks from the ATR-FTIR spectrum of G material could be assigned as follows: amide A (3400–3350 cm −1 , attributed to -νNH and -νOH vibrations), amide B (3085–3070 cm −1 ), amide I (1700–1600 cm −1 , corresponding to predominantly νC = O vibrations of protein amide), amide II (1600–1500 cm −1 , assigned to 60% bending (δ) vibrations NH and 40% of νC-N vibrations) and amide III (1200–1300 cm −1 , corresponding to νC-N and δN-H; this vibration overlaps with—δCH 2 vibrations). The vibration that appeared at 1715 cm −1 indicates the presence νCO of carbonyl group of tannic acid from G-material [ 60 ].…”

Properties of Freeze-Dried Gelatin/Clay Aerogel Composites Crosslinked with Tannic Acid

“…In addition to adding stability to the hydrogels, NaOH was added to promote cross-linking between the gelatin chains and the TA. This process has previously been performed in hydrogels under highly oxidative conditions due to exposure to bubbling oxygen using NaIO 4 , or other chemicals …”

Nanoarchitectonics of a Skin-Adhesive Hydrogel Based on the Gelatin Resuscitation Fluid Gelatinol®

“…Two control probes were used for comparison: opened (without hydrogel sample) and closed (with rubber plug). The flasks were placed in a thermostat under standard conditions for 24 h. The samples were removed from the necks and titrated (iodometric) to determine the content of active oxygen, according to a previously reported method [ 31 ].…”