Evaluating the Antibacterial and Anti‐Biofilm Properties of Chitosan Nanoemulsion Containing Euphorbia hebecarpa Plant Extract Against Escherichia coli and Staphylococcus aureus

ABSTRACT The use of nanoparticles as drug‐carrying systems in medicine has received much attention, and on the other hand, the use of plants with medicinal properties has advantages over synthetic drugs. This study aims to improve the antibacterial and anti‐biofilm properties of Euphorbia hebecarpa plant extract using chitosan nanoparticles. Extraction were performed using the modified maceration and methanol solvent. The agar disc diffusion method was carried out to investigate the antimicrobial effects and MIC at an optical density (OD) of 630 nm. The anti‐biofilm agent's influence was measured at OD 570 nm, and the metabolic activity of bacteria in the damaged biofilm was determined using triphenyl tetrazolium chloride (TTC) staining. The nanoparticles were obtained by following the ionic gelation method and its characteristics were evaluated. Chitosan nanoparticles loaded with plant extract were found to be spherical shape with hydrodynamic diameter of 142 nm, a polydispersity index (PDI) of 0.184, a zeta potential of +28.6 mV. It was determined that the loading capacity (% LC) and encapsulation efficiency (% EE) percentages were 33% and 40%, respectively. The diameter of the inhibition zone in the agar disc diffusion test for both bacteria using nanoparticles loaded with the extract increased compared with control groups. Also, at a concentration of 4 mg/mL of loaded nanoparticles, 49.33% of Escherichia coli biofilm and 62.7% of Staphylococcus aureus biofilm were destroyed. The data obtained from the tests performed in this study show that the use of Euphorbia plant extract in the form of chitosan nanoparticles can have more antimicrobial and anti‐biofilm effects.