Comparative Study on Different Clay Minerals for Costabilizing Antibacterial Pickering Emulsions with Sapindus Mukorossi against <i>MRSA</i> and ESBL-<i>E. coli</i>

Green Pickering emulsions were costabilized by different natural clay minerals and <i>Sapindus mukorossi</i> (<i>S. mukorossi</i>) for the encapsulation of carvacrol in this study, and the effect of the types of clay minerals on the emulsion stability and antibacterial activity of Pickering emulsions was studied, while the stability mechanism and surface/interfacial interaction of Pickering emulsions were revealed. The results suggested that the synergistic effect among the continuous-phase polymer, clay mineral, and organic substances derived from <i>S. mukorossi</i> was the predominant stabilization mechanism of Pickering emulsions, which formed a hybrid rigid shell on the oil-in-water interface. Meanwhile, Pickering emulsions presented excellent antibacterial activities against <i>Staphylococcus aureus</i> (<i>MRSA</i>) and extended-spectrum β-lactamases of <i>Escherichia coli</i> (ESBL<i>-</i> <i>E. coli</i>). By contrast, halloysite and <i>S. mukorossi</i> costabilized Pickering emulsions presented better emulsion stability and antibacterial activities toward <i>MRSA</i> and ESBL<i>-</i> <i>E. coli</i>, and lower visible colonies were observed for <i>MRSA</i> with a minimum inhibitory concentration of 2.5 μL/mL. The enhancement in the antibacterial activity was attributed to the increase in the water solubility of carvacrol and contact chance between the Pickering droplets and bacteria, because of which the structural integrity of drug-resistant bacteria was more easily destroyed. This study provides a feasible approach to engineer efficient antibacterial materials for industrial applications.