Study On The Preparation And Antibacterial Properties Of Plant Essential Oil With High Stability

Natural plant essential oils have antibacterial,antioxidant,anti-aging,anti-tumor growth and other medicinal effects,and have great application value in the medical field.However,due to poor water solubility and stability of plant essential oils,its bioavailability is low,which severely limits its application.This paper mainly studied the preparation of plant essential oil nanoemulsion.The plant essential oil was encapsulated by nanoemulsion technology to improve its the water solubility,and at the same time improved its stability and antibacterial activity,which made certain contributions to the practical application of plant essential oil.The main research work of this paper is as follows:1.The antibacterial activity of twelve natural plant essential oils against several common skin pathogenic bacteria(Pseudomonas aeruginosa,Staphylococcus aureus,Candida albicans and Malassezia furfur)was studied.With the determination of the minimum inhibitory concentration and inhibition zone experiment,four kinds of plant essential oils with strong antibacterial effect were screened out: citrus,citronella,peppermint and lavender essential oil.By studying the inhibitory effect of the essential oils on the four tested strains,we could find that the essential oils have a synergistic antibacterial effect.2.The citrus essential oil nanoemulsion was prepared by high pressure homogenization method,and three kinds of relatively stable emulsifiers were obtained through preliminary screening of different types of emulsifiers.Based on the compounding principle of emulsifiers,the three emulsifiers that had been initially screened were compounded,and the formulation of nanoemulsion was optimized by response surface methodology,and the best nanoemulsion formulation was obtained:6wt% Tween 80,3 wt% polyglycerol myristates,2 wt% polyglycerol monolaurates,5 wt% glycerol and 7.5 wt% sorbitol in the 100 g system.3.The stability and antibacterial properties of the obtained nanoemulsions were evaluated.Studies have shown that the citrus essential oil nanoemulsion exhibits good p H and ionic strength stability within 90 days.After high-speed centrifugation,15 cold-heat cycles and200-day storage,the nanoemulsion still maintained high transparency and small particle size,which indicated that we successfully prepared a highsteady-state citrus essential oil nanoemulsion.On the other hand,by separately determining the MIC of citrus essential oil and its nanoemulsion,its nanoemulsion exhibited more efficient antibacterial properties against several pathogens compared with free citrus essential oil,which was further confirmed by the observation of CLSM and SEM images.4.The preparation of compound essential oil nanoemulsion was carried out.After cold and heat cycles,treatment of different p H solutions and salt ion solutions,and storage for 105 days,the nanoemulsion still maintained high transparency and small particle size,which also showed that high stable compound essential oil nanoemulsion was successfully prepared.