Development of medicinal and aromatic herbal oil-based hydrojels for controlled release systems

In drugs produced by conventional methods, it may not be possible to transport the active substance to the targeted tissue or blood plasma at the specified dosage. This is due to the fact that the active substance is damaged in the upper gastrointestinal tract, has a short half-life in the blood, is consumed by other tissues and is difficult to enter the targeted tissue. For this reason, in the treatment of diseases such as intestinal tissue diseases and cancer that are difficult to treat with drugs, instead of drugs produced by traditional methods, smart drugs designed specifically for the disease that are released in accordance with controlled release mechanics have been started to be used. The design of controlled release devices for the production of smart drugs is an important academic field today. The design of hydrogel microsphere devices with stimulu-responsive from controlled release devices is one of the popular topics in this field of study. Especially the biocompatibility, biodegradability, low toxicity of microspheres synthesized from natural hydrogel polymers, easy and cheap synthesis with a wide variety of designs make these devices stand out. In this study, natural hydrogel microsphere drug precursors were synthesized from controlled drug release devices for oral controlled release of therapeutic plant oils. Thyme essential oil and calendula oil, which have therapeutic effects, were used as drug active ingredients. Carrier hydrogel microspheres were synthesized by ionic gelation as alginate and chitosan coated alginate microspheres. Characterization of the microspheres was performed by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy analysis. The release behavior of the hydrogel spheres was investigated in vitro at pH 1.2 and pH 6.8. When the encapsulation efficiency and drug loading capacity of the microspheres were examined, it was observed that the increase in oil concentration decreased the encapsulation efficiency and increased the drug loading capacity. The highest percent encapsulation efficiency was obtained in the KE-KS-2 microsphere (84%), while the highest percent drug loading capacity was obtained in the KE-KS-5 microsphere (67%). When the release kinetics of the microspheres were examined, it was observed that the release at pH 1.2 generally followed the Higuchi kinetic model, while the release at pH 6.8 followed the Korsmeyer-Peppas model. At the end of the release study, the highest percent cumulative release occurred in the KE-KS-2 microsphere (63%). The chitosan coating improved the release profile by extending the release time while reducing the cumulative percent release. When the swelling behavior of the microspheres at pH 1.2 and pH 6.8 was examined in the swelling experiments, it was observed that the microspheres showed high swelling at pH 6.8.