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

Abstract

Considering the FAO perspectives for agriculture towards 2030 many natural sources will be no longer profitable for the synthesis of many biomaterials; however, triticale (X Triticosecale Wittmack) is a cereal crop synthetized to withstand marginal agricultural conditions, used primarily as fodder throughout the world. The synthesis of a novel anionic hydrogel with pH stimulus-response was developed based on Eronga triticale starch as sustainable biomass, using citrate (pKa~3.1, 4.7 and 6.4) as crosslinking 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 by a thermal analysis the hydrogels exhibited four endothermic curves (115-393°C, ~1.4-38 kJ/mol activation energy). The rheological analysis showed viscoelastic tendency (G’>G’’) and good stability (Tan δ<1) in the 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 bovine albumin with the increase of pH~3-7.8 by anomalous and case-II diffusion with greater release at pH~7.8/3.5h (80-96%). The hydrogel showed good physical and diffusion performance, however, we aim to expand the biomaterials area using triticale starch due to its limited investigations, low-cost and green modification.