Triticale Starch-Based pH-Responsive Hydrogel: Synthesis, Characterization, Diffusion & New Perspective of Triticale Crop as Sustainable Source for Stimuli-Response Hydrogels

Considering the FAO perspectives for agriculture towards 2030, many natural sources will be no longer profitable for the synthesis of many biomaterials. Triticale (X Triticosecale Wittmack) is a cereal crop synthesized to withstand those marginal conditions; however, it is primarily used as fodder worldwide. We reported for the first time the synthesis of a natural anionic hydrogel with gastrointestinal pH stimulus-response as new alternative of smart material, based on Eronga triticale starch as sustainable biomass, using citrate (pKa~3.1, 4.7 and 6.4) as cross-linking agent. By scanning electron microscopy and X-ray diffraction, starch granules exhibited size and semi-crystallinity A-type. The presence of the anionic sensing group (COOH) was verified by infrared spectroscopy, and through thermal analysis hydrogels exhibited four endothermic curves (115-393°C, ~1.4-38 kJ/mol Ea). The rheological analyzes showed viscoelastic tendency (G’>G’’) with high stability (Tan δ<1) in frequency, time, and strain sweeps. Gastrointestinal pH sensitivity (~2-7.8) was verified (α≤0.01) following Fick’s diffusive parameters, which resulted in a tendency to gradually release BSA with increasing pH~3-7 by anomalous and case-II diffusion, showing greater release at pH~7.8/3.5h (80-96%). We aim to expand the biomaterials area focusing on triticale starch due its limited reported investigations, low-cost, green modification, and its rheological performance as plastic.