Abstract: A carbopol loaded-Surfactin antibacterial gel was prepared by using Surfactin as a major effective component, carbopol as a thickener and triethanolamine as a neutralizer. The formulation was optimized using response surface methodology with Box-Behnken design. Three dependent variables were considered: diameter of inhibition zone, pH and viscosity of the gel. The optimal formulation was determined as follows: Surfactin 0.60%, carbopol 0.35%, and triethanolamine 0.30%. The optimized gel was transparent and stable with effective antibacterial activity, and the disruption of mature Staphylococcus aureus biofilm by the gel was improved obviously as compared with sterile water. After being treated with the Surfactin gel, the biofilm showed lighter color and sparse distribution with a certain light transmittance and high disruption.

Key words: Surfactin, carbopol, antibacterial gel, Staphylococcus aureus, biofilm