Enhancing the targeting performance and prolonging the antibacterial effects of clove essential oil liposomes to Campylobacter jejuni by antibody modification.

The application of plant essential oil liposomes to prevent and control food safety risks caused by Campylobacter jejuni (C. jejuni) still faces challenges such as lack of targeting and low release rate. Here, a bacteria-targeted and protease-activated antibacterial liposome (ACCLPs) was successfully synthesized through encapsulation of clove essential oil (CEO) by film dispersion method, embedding of casein by freeze-thaw method, and conjugation of C. jejuni antibody on the liposome membrane by post-insertion method. The average particle size, the essential oil encapsulation rate, the casein mosaic rate, and the antibody coupling efficiency of ACCLPs were determined as185.87 nm,16.9%,70.1% and 87.5%, respectively. The modification with C. jejuni antibody could significantly improve the targeting of ACCLPs to C. jejuni. Controlled release experiments showed that the exocrine protease from C. jejuni could hydrolyze the embedded casein and perforation on the ACCLPs, thus leading to a bacteria-dependent CEO release and significant prolonging the antibacterial effects of ACCLPs. Application results of ACCLPs on C. jejuni-contaminated foods showed that ACCLPs could effectively inhibit C. jejuni in a variety of meat products, fruits and vegetables and extend their shelf life without significantly affecting food quality. The results above in this work would provide a new view for the development of high efficient liposome-based antibacterial system of plant essential oil.

Antibacterial mechanisms of clove essential oil against Staphylococcus aureus and its application in pork.

Clove essential oil (CEO) has been widely used in the processing of meat products due to its potent antibacterial activity and special aroma. However, studies on the antibacterial mechanism of CEO are still not detailed enough. The aims of this study were to investigate the antibacterial mechanisms of action of CEO against Staphylococcus aureus in detail and evaluate its efficacy in pork preservation. The Staphylococcus aureus cells treated with CEO were morphologically damaged and had significant leakage of intracellular components. At the metabolic level, CEO significantly inhibited the respiratory metabolism of Staphylococcus aureus by inhibiting the tricarboxylic acid cycle pathway and the total inhibition rate was found to be 31.23 %. Molecular biology experiments showed that CEO could interact with Staphylococcus aureus DNA molecules and affect the accessory gene regulator (Agr) system, which resulted in a significant decrease in the expression levels of Staphylococcus aureus virulence genes so that the expression of sea and hla decreased by 82.97 % and 77.27 %, respectively. Molecular docking results indicated that the interaction between eugenol, the main active ingredient in CEO, and the key phosphorylase Agr C in the Agr system may be one of the main reasons for the inhibition. The application results showed that CEO had a good antibacterial effect in pork for 7 days without affecting the texture of pork. The results obtained in this study provide a reference for an in-depth study of the detailed antibacterial mechanism of natural food antibacterial agents.

Encapsulation of essential oil components with methyl-ß-cyclodextrin using ultrasonication: Solubility, characterization, DPPH and antibacterial assay.

Essential oils derived from medicinal plants are prosperous sources of active components having high biological potential. Cuminaldehye and isoeugenol, are hydrophobic essential oil components (EOC), are showing drastic limitations in their applications by low water solubility and the respective volatility. Methyl-ß-cyclodextrin inclusion complexes (MßCD-ICs) were prepared in aqueous solution and in solid state with the EOC via the ultrasonication method, an energy saving, high efficiency and eco-friend technique, aim to extend their aqueous solubility and biological properties. UV-Vis absorption, fluorescence, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), proton nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD) and computational simulations confirmed the formation of EOC/MßCD-ICs. Result of solubility studies proved the enhanced solubilization of EOC in the presence of MßCD in aqueous and double reciprocal profiles substantiated the guest/host stoichiometry of 1:1. TGA and DSC studies indicated the improved stability of EOC in MßCD-ICs. The efficiency of ICs in terms of the antioxidant activity was verified and the IC displayed higher antioxidant activity compared to that of free EOC, as determined by free radical scavenging assay. Finally, the antibacterial effect of EOC/MßCD-ICs against gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria was demonstrated. Overall results not only revealed the potential of MßCD on the bioavailability, solubility and stability, but also that the intensification caused by the IC may be greater that the antioxidant and antibacterial effects of the selected EOC for this study.

The antibacterial activity of clove oil/chitosan nanoparticles embedded gelatin nanofibers against Escherichia coli O157:H7 biofilms on cucumber.

This study aims to evaluate the antibacterial activity of clove oil-loaded chitosan nanoparticles (CO@CNPs) and gelatin electrospun nanofibers against Escherichia coli O157:H7 (E. coli O157:H7) biofilms on cucumbers. The optimal CO@CNPs were prepared when the initial concentration of clove oil (CO) was 2.5mg/mL according to the ionic crosslinking method. CO@CNPs showed high antibacterial activity against E. coli O157:H7 biofilms. After 8h treatment, almost 99.98% reduction in E. coli O157:H7 population was achieved when CO@CNPs were applied at 30% (w/v). Subsequently, the prepared CO@CNPs were incorporated successfully within gelatin nanofibers by electrospinning. After 9mg/mL gelatin/CO@CNPs treatment for 24h, the population of E. coli O157:H7 biofilm reduced by about 99.99% in vitro. Further, the application of gelatin/CO@CNPs nanofibers on cucumber against E. coli O157:H7 biofilm was evaluated as well. After 6mg/mL and 9mg/mL gelatin/CO@CNPs nanofibers treatment at 12°C for 4days, 4.28 and 4.97 log10 reductions of E. coli O157:H7 biofilm in population were observed, respectively. Finally, the sensory evaluation results implied that the gelatin/CO@CNPs nanofibers treatment could maintain the color and flavor of cucumber well for >4days.

Plasma-treated poly(ethylene oxide) nanofibers containing tea tree oil/beta-cyclodextrin inclusion complex for antibacterial packaging.

This work describes the effect of cold nitrogen plasma to enhance the antibacterial activity of poly(ethylene oxide) (PEO) nanofibers containing antibacterial agent. Beta-cyclodextrin (ß-CD) and tea tree oil (TTO) were used as a host-guest to form water-soluble inclusion complex. The encapsulation efficiency of TTO in inclusion complex could reach 73.23% at 60°C. As antibacterial agent, the inclusion complex was encapsulated into PEO matrix by electrospun. After plasma treatment, the release efficiency of antibacterial agent from PEO nanofibers was improved. As a result, the antibacterial activity of PEO nanofibers was enhanced accordingly. The plasma-treated nanofiber membranes achieved the highest antibacterial activity against Escherichia coli O157:H7, which was tested on the beef for 7d, with inhibition efficiently of 99.99% whether at 4°C or 12°C. The plasma-treated PEO nanofiber membranes containing TTO/ß-CD inclusion complex (TTO/ß-CD-IC) can prolong the shelf-life of beef, suggesting it has potential application in active food packaging.

Antibacterial poly(ethylene oxide) electrospun nanofibers containing cinnamon essential oil/beta-cyclodextrin proteoliposomes.

A novel antibacterial packaging material was engineered by incorporating cinnamon essential oil/ß-cyclodextrin (CEO/ß-CD) proteoliposomes into poly(ethylene oxide) (PEO) nanofibers by electrospinning technique. Herein, PEO was a stabilizing polymer and used as electrospinning polymeric matrix for the fabrication of CEO/ß-CD proteoliposomes nanofibers. The nanoliposomes were inlaid with protein are defined as proteoliposomes. Taking advantage of bacterial protease secreted from Bacillus cereus (B. cereus), the controlled release of CEO from proteoliposomes was achieved via proteolysis of protein in proteoliposomes. The CEO/ß-CD inclusion complex was prepared by the aqueous solution method and characterized by Raman and FTIR spectroscopy. After the treatment of CEO/ß-CD proteoliposomes nanofibers packaging, the satisfactory antibacterial efficiency against B. cereus on beef was realized without any impact on sensory quality of beef. This study demonstrated that the CEO/ß-CD proteoliposomes nanofibers can significantly extend the shelf life of beef and have potential application in active food packaging.

Nanoliposomes containing Eucalyptus citriodora as antibiotic with specific antimicrobial activity.

Bacterial infections are a serious issue for public health and represent one of the major challenges of modern medicine. In this work, a selective antimicrobial strategy based on triggering of pore-forming toxin, which is secreted by infective bacteria, was designed to fight Staphylococcus aureus. The antimicrobial activity is realized by employing Eucalyptus citriodora oil as antibiotic which in this study is encapsulated in nanoliposomes.

[Comparison of Dongeuisoosebowon sasung caobenjuan (The Four Constitutional Medicine of A Draft Volume of Longevity and Life Preservation in Eastern Medicine) and Dongeuisoosebowon (Longevity and Life Preservation in Eastern Medicine)].

In 1894, Lee Je-ma finished the book Dongeuisoosebowon sasung caobenjuan (The Four Constitutional Medicine of A Draft Volume of Longevity and Life Preservation in Eastern Medicine), and later, in 1900, he started revising the book. However, he passed away and didn't finish his work. In 1901, Lee's disciples edited the revised edition, and published it in the title Dongeuisoosebowon (Longevity and Life Preservation in Eastern Medicine). Some hand-copied versions of Dongeuisoosebowon sasung caobenjuan were still available. After comparing these two books, it was found that Lee's disciples made rather more changes: including addition of its contents, adjustment of its order, modification of the texts and prescriptions, etc. By comparison, the contents in the hand-copied edition more closely reflects Lee's recognition on the Sasung Euihak (Four-Constitution medicine), while those of the published ones were deleted a bulk of the original contents of the Four-Constitutional medicine, yet supplemented much contents of traditional Chinese medicine.