Biocompatible stimuli responsive hydrogels of okra mucilage with acrylic acid for controlled release phytochemicals of Calendula officinalis: In vitro assay

Abstract

Mucilage is a natural biopolymer present in plants. These have found a variety of applications in the areas of agriculture, food, and the pharmaceutical sector as binders, disintegrators, emulsifiers, and suspending and gelling agents, to mention a few. Mucilage has traditionally been used as such because they are biodegradable, biocompatible, and non-toxic. However, simple modifications lead to the formation of hydrogels with valuable properties when compared with those of synthetic origin. Okra mucilage was extracted and characterized for the constituent phytochemicals. The extracted okra (OKR) mucilage was chemically modified with acrylic acid (AA) to improve upon the properties of mucilage. The modifications were carried out using a cross-linker (EGDMA) followed by an initiator, potassium persulfate (KPS), in varying ratios. The polymers were standardized and optimized to show maximum swelling in distilled water, glucose, and saline solutions. The swelling was also studied at different pH levels (2, 4, 7, and 8). The developed hydrogels were characterized by FTIR, SEM, and XRD studies. The biocompatibility of the polymer was studied by evaluating the protein absorption and blood compatibility. Calendula officinalis was selected for the release study as it possesses medicinal properties. The hydrogels with maximum swelling properties were encapsulated with extracts containing phytochemicals, and an in vitro release study was carried out to study the release behavior. The encapsulation efficiency of OKR-AA hydrogels was observed to be 61% after 24 h of exposure. The in vitro studies have proved that the hydrogels have good drug release capability and can thus be explored for biomedical applications.