Particle morphology and antimicrobial properties of electrosprayed propolis

In this study, propolis resin was electrosprayed (ES) without a carrier polymer in order to produce nanoparticles, and the parameters affecting the ES process were investigated. During preliminary experiments, surface tension, electrical conductivity, dielectric, and rheological properties of the feed solution and their effects on electrospraying of propolis were determined. Afterward, the propolis solution was fed to the electrospinning equipment at the different feed rates (1, 5.5, and 10 ml/h), the voltages (5, 12.5, and 20 kV), and the distances to the collector plate (5, 10, and 15 cm). According to the response surface analysis (RSA), the feed rate and the applied voltage were effective for the morphology and diameter of particles. In contrast, the antimicrobial activity of particles against Staphylococcus aureus and Escherichia coli depended on the feed rate and the distance to the collector plate. Based on these results, the optimum feed rate, applied voltage, and distance to the collector plate conditions for ES of propolis were found as 8.82 ml/h, 20 kV, and 5 cm, respectively.