Injectable Alginate-Collagen Hydrogel with Propolis: A Potential Cardioprotective Biomaterial

Injectable hydrogel has become a viable therapeutic approach for the non-invasive treatment of myocardial infarction. Although natural and synthetic injectable hydrogel has been investigated, it typically exhibits a deficiency in cardioprotective characteristics. Therefore, this study aims to develop and characterize an injectable alginate-collagen hydrogel incorporated with propolis and crosslinked with calcium gluconate. The sample was developed by incorporating alginate, collagen, and varying quantities of propolis at 3%, 7%, and 10%. Subsequently, it was crosslinked with calcium gluconate to create a hydrogel. The rheology test results showed that jellification occurred at 37°C following the incorporation of 0.5% calcium gluconate, as evidenced by an elevation in storage modulus and a reduction in loss modulus. An increase in calcium gluconate facilitated crosslinking while concurrently leading to an increase in swelling degree of up to 17 times. This phenomenon was caused by the favorable water permeability of calcium ions. The results also showed that the elevation of propolis diminished the extent of swelling due to the enhancement of density. The elevated concentration of calcium gluconate reduced the degradation rate, but the increased amount of propolis accelerated the breakdown. The antioxidant activity assessed using DPPH assays showed that the percentage of inhibition increased along with the concentrations of propolis. Based on these results, propolis can be integrated into injectable hydrogel for potential therapeutic therapy of myocardial infarction.