Study of Gelatin-grafted-2-Acrylamido-2-methylpropane sulfonic acid hydrogels as a controlled release vehicle for amorphous solid dispersion of Tripterygium Wilfordii bioactive constituents

The development of controlled-release preparations for herbal medicines remains challenging due to their complex compositions and distinct physicochemical properties. Tripterygium Wilfordii (TWHF) is a traditional Chinese medicine used to treat inflammatory diseases like rheumatoid arthritis, neurodegenerative and autoimmune diseases. The main active ingredients include diterpenes, triterpenes and alkaloids. These agents have poor pharmacokinetic and physicochemical characteristics, making it difficult to achieve therapeutic benefits. In the present study, a solid dispersion of TWHF (TWHF-SD) was prepared and loaded into Gelatin-grafted-2-Acrylamido-2-methylpropane sulfonic acid hydrogels (Gelatin-g-AMPS) for controlled drug release. A total of 48 compounds were identified in TWHF-SD using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis. The hydrogel's structure and physicochemical properties were confirmed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis   (TGA), and Differential Scanning Calorimetry (DSC). Studies regarding hydrogel structure–function relationships were conducted, such as average weight between two or mor crosslinks (Mc), polymer volume fraction (V2,s), and diffusion coefficient (D). Hydrogel swelling and drug release from loaded hydrogels were slightly higher at pH 1.2 (swelling ratio of 60.84%, drug release of 85.08) than at pH 7.4 (swelling ratio of 46.46%, drug release of 75.03%) after 48 h. The gel fraction of hydrogel increased with increasing polymer/crosslinker ratios. Additionally, in vitro studies confirmed that the developed hydrogels were effective against bacterial growth and had good antioxidant properties.