Fabrication and antibacterial evaluation of peppermint oil-loaded composite microcapsules by chitosan-decorated silica nanoparticles stabilized Pickering emulsion templating.

Novel peppermint oil (PO)-loaded composite microcapsules (CM) with hydroxypropyl methyl cellulose (HPMC)/chitosan/silica shells were effectively fabricated by PO Pickering emulsion, which were stabilized with chitosan-decorated silica nanoparticles (CSN). The surface modification of chitosan could improve the hydrophobicity of silica nanoparticles and favor their adsorption at the oil-water interface of PO Pickering emulsions. The microcapsule composite shells were formed dependent on the electrostatic adsorption of HPMC and CSN, and further subjected to spray-drying. The peppermint oil-loaded composite microcapsules with 100% HPMC as wall material (PO-CM@100%HPMC) seemed to be optimum formulation based on the prolonged release, acceptable entrapment efficiency (89.1%) and drug loading (25.5%). The PO-CM@100%HPMC could remarkably prolong the stability of PO. Moreover, the PO-CM@100%HPMC had a long-term antimicrobial activity (85.4%) against S. aureus and E. coli even after storage for 60 days. Therefore, the Pickering emulsions based microcapsules seemed to be a promising strategy for antibacterial application for PO.

Cellulose nanocrystals based clove oil Pickering emulsion for enhanced antibacterial activity.

An effective antibacterial system was developed by using clove essential oil Pickering emulsion (CO-PE). The carboxymethyl cellulose sodium modified cellulose nanocrystals (CNC) was used as the stabilizer of CO-PE, which were prepared by environmentally friendly approach of homogenization technology. The factors affecting the formation and stability of CO-PE were studied, such as CNC concentration, homogenization pressure, CO concentration and ionic concentration and pH. And the antibacterial performance of CO-PE against E. coli and S. aureus was investigated by determining the minimal inhibitory concentration (MIC). The results showed that 1% CNC stabilized CO-PE exhibited small droplet size and rough surface, and had good stability at high pH values or salt concentration, owing to the presence of CNC on interface of droplet. And the CNC-stabilized CO-PE exhibited higher antimicrobial activity at equivalent CO concentration, which might be attributed to efficiently adhere to bacterial membrane. Therefore, our research would provide new insights for antibacterial application of Pickering emulsions loading essential oils in the food and other industries.