| Pickering emulsion is an emulsion stabilized by solid particles which adsorb on the oil-water interface.Pickering emulsion shows a good thermodynamic stability due to the irreversible adsorption process of solid particles at the oil-water interface,and because the controllable surface properties,low dosage,strong stability,green environmental pollution,good biocompatibility of these solid particles,Pickering emulsion displays many potential applications in food,cosmetics,pharmaceutical and other fields.In addition,the preparation of microcapsules using Pickering emulsion as template has attracted more and more attention because of its safety,non-toxicity and simple preparation method.A biocompatible oil-in-water emulsion containing no surfactant or other organic modifier was prepared using two negatively charged,naturally derived materials: alginate(Alg)and montmorillonite(MMT),and it was found that the stable emulsion has good storage stability and coalescence stability.The dispersing and suspending effects of Alg to MMT were observed,and the interaction between Alg and MMT was confirmed by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and Zeta potential.The distribution of particles at the oil-water interface and in the aqueous phase of the emulsion was observed by confocal laser scanning microscopy(CLSM)and scanning electron microscopy(SEM).An unique mechanism of the stable Pickering emulsion was then proposed.It is demonstrated that Alg not only thicken the continuous phase,create a gel-like environment around the droplets,but also could modify the MMT surface,synergistically enhance the electrostatic force of droplets due to the same charge property with MMT.Moreover,the rheological properties of the emulsion co-stabilized by MMT/Alg can be well adjusted using various stimuli including p H and salt.In general,this work presents a highly stable,tunable and biocompatible emulsion for potential applications in food and cosmetic products.Based on the Pickering emulsion prepared by MMT and Alg,carvacrol loaded Pickering emulsion was prepared by adjusting the proportion of carvacrol.The effects of different composition of oil phase on the particle size and stability of the emulsion were studied,and the carvacrol loaded Pickering emulsion with uniform droplet size,good stability and high entrapment rate was obtained.Through the determination of pyocyanin and biofilm content and the inhibitory effect on the movement ability of bacteria,the effect of carvacrol loaded Pickering emulsion in the field of anti-quorum sensing activity was confirmed,and the treated bacteria were further observed by SEM,which directly confirmed the results.Compared with pure carvacrol essential oil,the protective effect of MMT-based emulsion entrapment system on carvacrol and the improvement of carvacrol bioavailability were confirmed.Microcapsules were prepared by ionic cross-linking of the Alg of the prepared Pickering emulsion,in which a solid lipid mixed with carvacrol was chose as the oil phase.The effects of Alg concentration,oil-water ratio and oil phase composition on the preparation of microcapsules were investigated,and microcapsule with an optimized entrapment efficiency rate and dispersity was selected for anti-quorum sensing experiment.The results showed that the performance of carvacrol loaded microcapsules was much better than that of non cross-linked emulsion,and the quorum sensing inhibition rate of Pseudomonas aeruginosa was higher at the same concentration.Finally,the mechanism of anti-quorum sensing activity of carvacrol loaded microcapsules was provided.This study proposes a mild and non-toxic encapsulation system for quorum sensing inhibitors,which has potential applications in anti-quorum sensing. |
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