Physico-Chemical and Structural Characterization of Mixed Natural Polymer Hydrogels Under Simulated Gastrointestinal Fluid

The gastrointestinal track has a varied pH, from an acidic pH in the stomach to a slightly basic pH in the intestine. The pH difference creates problems for the delivery of drugs and nutrients, as the active compounds may not survive the changing pH. Incorporating active ingredients into hydrogels can protect the compounds from degradation. Natural polymer hydrogel is preferable because of its safety and compatibility. However, a suitable formula should be optimized to facilitate suitable delivery in the gastrointestinal track. In this study, we produced hydrogels with 10 different formulas of mixed natural polymers: CMC (C), alginate (A), chitosan (X), and/or guar gum (G). The resulting hydrogels were characterized using swelling performance tests at pH 2 and 6.8, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Hydrogels with the formula of C50A25X25, C25A50X25, C25A50G25, C25A25G50, C25A50X12.5G12.5, and C25A25X25G25 are not digested at pH 2, but those hydrogels are digested at pH 6.8. The FTIR spectra of the hydrogels show functional groups of O–H, C=O, C–O, and C–H. Meanwhile, the SEM results show cracking phenomena on the surface of the hydrogels C50A25X12.5G12.5, C25A50X12.5G12.5, and C25A25X25G25. This study offers a general guide for the development of a natural polymer hydrogel as a suitable nutrient vehicle in the gastrointestinal track. Formulation of each type of nutrient should be optimized for optimum delivery to the designated part of the gastrointestinal track.