Phosphatidylcholine Liposomes Research Articles

Inhibition of cryoaggregation of phospholipid liposomes by an Arabidopsis intrinsically disordered dehydrin and its K-segment

Dehydrin is an intrinsically disordered protein involved in the cold tolerance of plants. Although dehydrins have been thought to protect biomembranes under cold conditions, the underlying protective mechanism has not been confirmed. Here we report that Arabidopsis dehydrin AtHIRD11 inhibited the aggregation of phospholipid liposomes after freezing and thawing. AtHIRD11 showed significantly greater cryoaggregation-prevention activity than cryoprotective agents such as trehalose, proline, and polyethylene glycols. Amino acid sequence segmentation analysis indicated that the K-segment of AtHIRD11 inhibited the cryoaggregation of phosphatidylcholine (PC) liposomes but other segments did not. This showed that K-segments conserved in all dehydrins were likely to be the cryoprotective sites of dehydrins. Amino acid replacement for a typical K-segment (TypK for short) sequence demonstrated that both hydrophobic and charged amino acids were required for the cryoaggregation-prevention activity of PC liposomes. The amino acid shuffling of TypK remarkably reduced cryoprotective activity. Although TypK did not bind to PC liposomes in solution, the addition of liposomes reduced its disordered content under crowded conditions. Together, these results suggested that dehydrins protected biomembranes via conserved K-segments whose sequences were optimized for cryoprotective activities.

Chimeric liposomes decorated with P407: an alternative biomaterial for producing stealth nano-therapeutics

The aim of the present study is the development and evaluation of the physicochemical properties of chimeric hydrogenated soya phosphatidylcholine (HSPC) and egg phosphatidylcholine (EggPC) liposomes with incorporated triblock copolymer Poloxamer P407 (P407). The physicochemical assay was held in water HPLC-grade and Foetal Bovine Serum (FBS), in order to determine whether these systems can be used as drug or antigen delivery nanosystems. Dynamic and electrophoretic light scattering (DLS/ELS) techniques were used for the measurement of the hydrodynamic diameter, the polydispersity index, and the ζ-potential of the prepared nanosystems. The incorporation of the P407 resulted in a size reduction of all systems. A decrease in the hydrodynamic diameter and polydispersity index were also found as a result of increasing the storage temperature from 4 °C to 25 °C, attributed to P407. The experiments that were carried out in FBS, showed that the addition of P407 improved systems stealth properties. Concluding, we propose P407 as a promising alternative to PEG in the development of lipid nanoparticles with optimized bio- and shelf-stability.

Phosphatidylserine receptors enhance SARS-CoV-2 infection.

Phosphatidylserine (PS) receptors enhance infection of many enveloped viruses through virion-associated PS binding that is termed apoptotic mimicry. Here we show that this broadly shared uptake mechanism is utilized by SARS-CoV-2 in cells that express low surface levels of ACE2. Expression of members of the TIM (TIM-1 and TIM-4) and TAM (AXL) families of PS receptors enhance SARS-CoV-2 binding to cells, facilitate internalization of fluorescently-labeled virions and increase ACE2-dependent infection of SARS-CoV-2; however, PS receptors alone did not mediate infection. We were unable to detect direct interactions of the PS receptor AXL with purified SARS-CoV-2 spike, contrary to a previous report. Instead, our studies indicate that the PS receptors interact with PS on the surface of SARS-CoV-2 virions. In support of this, we demonstrate that: 1) significant quantities of PS are located on the outer leaflet of SARS-CoV-2 virions, 2) PS liposomes, but not phosphatidylcholine liposomes, reduced entry of VSV/Spike pseudovirions and 3) an established mutant of TIM-1 which does not bind to PS is unable to facilitate entry of SARS-CoV-2. As AXL is an abundant PS receptor on a number of airway lines, we evaluated small molecule inhibitors of AXL signaling such as bemcentinib for their ability to inhibit SARS-CoV-2 infection. Bemcentinib robustly inhibited virus infection of Vero E6 cells as well as multiple human lung cell lines that expressed AXL. This inhibition correlated well with inhibitors that block endosomal acidification and cathepsin activity, consistent with AXL-mediated uptake of SARS-CoV-2 into the endosomal compartment. We extended our observations to the related betacoronavirus mouse hepatitis virus (MHV), showing that inhibition or ablation of AXL reduces MHV infection of murine cells. In total, our findings provide evidence that PS receptors facilitate infection of the pandemic coronavirus SARS-CoV-2 and suggest that inhibition of the PS receptor AXL has therapeutic potential against SARS-CoV-2.

Antiviral Potential of Naphthoquinones Derivatives Encapsulated within Liposomes.

HSV infections, both type 1 and type 2, are among the most widespread viral diseases affecting people of all ages. Their symptoms could be mild, with cold sores up to 10 days of infection, blindness and encephalitis caused by HSV-1 affecting immunocompetent and immunosuppressed individuals. The severe effects derive from co-evolution with the host, resulting in immune evasion mechanisms, including latency and growing resistance to acyclovir and derivatives. An efficient alternative to controlling the spreading of HSV mutations is the exploitation of new drugs, and the possibility of enhancing their delivery through the encapsulation of drugs into nanoparticles, such as liposomes. In this work, liposomes were loaded with a series of 2-aminomethyl- 3-hydroxy-1,4-naphthoquinones derivatives with n-butyl (compound 1), benzyl (compound 2) and nitrobenzene (compound 3) substituents in the primary amine of naphthoquinone. They were previously identified to have significant inhibitory activity against HSV-1. All of the aminomethylnaphthoquinones derivatives encapsulated in the phosphatidylcholine liposomes were able to control the early and late phases of HSV-1 replication, especially those substituted with the benzyl (compound 2) and nitrobenzene (compound 3), which yields selective index values that are almost nine times more efficient than acyclovir. The growing interest of the industry in topical administration against HSV supports our choice of liposome as a drug carrier of aminomethylnaphthoquinones derivatives for formulations of in vivo pre-clinical assays.

Soft dosage forms as interfaces

Aim. To analyze data on combined drugs in soft dosage forms as potential drug interfaces. Materials and methods. The bibliosemantic research method was used in the work. Results and discussion. By analogy with foreign interfaces of carbon nanotubes with neurons it has been proposed to consider a number of soft dosage forms as interfaces between inanimate organic structures of dosage forms and living cells of the skin tissue or the mucous membrane. A number of soft dosage forms, which can be considered as interfaces between the inanimate organics of dosage forms and living cells of the skin tissue and mucosa, has been studied and analyzed. Interfaces are polymer matrices made of polyethylene glycols, high molecular weight polysaccharides, carbomers, etc. A carbomer can be considered as the basis of plastic, conformationally mobile interfaces between the general dosage form and living cells of the skin and mucosa. It has been shown that the mechanism of increasing biocompatibility with the help of polyethylene glycols is the ability of PEG molecules due to compaction (spiralization) or expansion of the molecules to accept the optimal conformation, giving their hydrophobic or polar groups for the optimal binding, on the one hand, with medicinal substances (drugs), and, on the other hand, with bioobjects. It has been shown that the affinity for PEG-400 phosphatidylcholine liposomes is 6 times greater than that of propylene glycol, and the affinity for PEG-1500 liposomes is 24 times higher than that of propylene glycol. Upon contact with the skin or the mucosa the interface structure may be destroyed as the components of the dosage form have different affinities for membranes of cells of biological surfaces – surface active substances that quickly bind to the lipid bilayer of the membranes of the skin or mucous membranes are the first ones that leave the dosage forms. Then, other auxiliary substances of the interface bind to the cell membranes at different speeds and in different ways. Conclusions. Therefore, a dosage form as an interface is a dynamic matrix that can rebuild and, as it contacts the membranes of skin cells or mucous membranes, promote absorption of the drug substance according to a specific program.

Anti-Diabetic and Antioxidant Activities of Red Wine Concentrate Enriched with Polyphenol Compounds under Experimental Diabetes in Rats.

We obtained red wine concentrate, which was enriched with natural polyphenolic compounds (PC concentrate). The main purpose was to study the hypoglycemic and antioxidant effects of the red wine concentrate, and its impact on key hematological parameters of rats with experimental diabetes mellitus. While administrating the red wine concentrate to rats with diabetes, partial recovering of glucose tolerance was promoted, as well as normalization of glycated hemoglobin level, an increase in the quantity of erythrocytes and hemoglobin concentration. PC concentrate had anti-radical effect, which was determined using 2,2-diphenyl-1-picrylhydrazylradical (DPPH) method and effectively inhibited oxidation of phosphatidylcholine liposomes, induced by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) as a free radical generator. It was also confirmed that PC concentrate had antioxidant properties in vivo. The contents of lipid peroxidation and protein oxidation products, the activity of catalase, and glutathione peroxidase (GPx) were increased in the plasma of rats with diabetes mellitus. At the same time, the activity of superoxide dismutase (SOD) was decreased. The concentrate of red wine had a corrective effect on investigated indicators and caused their normalization in plasma of diabetic animals.

Specific and nondisruptive interaction of guanidium-functionalized gold nanoparticles with neutral phospholipid bilayers

Understanding and controlling the interaction between nanoparticles and biological entities is fundamental to the development of nanomedicine applications. In particular, the possibility to realize nanoparticles capable of directly targeting neutral lipid membranes would be advantageous to numerous applications aiming at delivering nanoparticles and their cargos into cells and biological vesicles. Here, we use experimental and computational methodologies to analyze the interaction between liposomes and gold nanoparticles (AuNPs) featuring cationic headgroups in their protecting monolayer. We find that in contrast to nanoparticles decorated with other positively charged headgroups, guanidinium-coated AuNPs can bind to neutral phosphatidylcholine liposomes, inducing nondisruptive membrane permeabilization. Atomistic molecular simulations reveal that this ability is due to the multivalent H-bonding interaction between the phosphate residues of the liposome’s phospholipids and the guanidinium groups. Our results demonstrate that the peculiar properties of arginine magic, an effect responsible for the membranotropic properties of some naturally occurring peptides, are also displayed by guanidinium-bearing functionalized AuNPs.

Modeling the saturation of detergent association in mixed liposome systems

Cells tune the lipid types present in their membranes to adjust for thermal and chemical stability, as well as to promote association and dissociation of small molecules and bound proteins. Understanding the influence of lipid type on molecule association would open doors for targeted cell therapies, in particular when molecular association is observed in the presence of competing membranes. For this reason, we modeled and experimentally observed the association of a small molecule with two membrane types present by measuring the association of the detergent Triton X-100 with two types of liposomes, egg phosphatidylcholine (ePC) liposomes and egg phosphatidic acid (ePA) liposomes, at varying ratios. We called this mixed liposomes, as each liposome population was formed from a different lipid type. Absorbance spectrometry was used to observe the stages of detergent association with mixed liposomes and to determine the detergent concentration at which the liposomes were fully saturated. A saturation model was also derived that predicts the detergent associated with each liposome type when the lipid bilayers are fully saturated with detergent. The techinical input parameters for the model are the detergent to lipid ratio and the relative absorbance intensity for each of the pure liposome species at saturation. With that, the association of detergent with any mixture of those liposome types at saturation can be determined.

Interactions of primaquine and chloroquine with PEGylated\ufeff phosphatidylcholine liposomes

This study aimed to analyze the interaction of primaquine (PQ), chloroquine (CQ), and liposomes to support the design of optimal liposomal delivery for hepatic stage malaria infectious disease. The liposomes were composed of hydrogenated soybean phosphatidylcholine, cholesterol, and distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy[polyethyleneglycol]-2000), prepared by thin film method, then evaluated for physicochemical and spectrospic characteristics. The calcein release was further evaluated to determine the effect of drug co-loading on liposomal membrane integrity. The results showed that loading PQ and CQ into liposomes produced changes in the infrared spectra of the diester phosphate and carbonyl ester located in the polar part of the phospholipid, in addition to the alkyl group (CH2) in the nonpolar portion. Moreover, the thermogram revealed the loss of the endothermic peak of liposomes dually loaded with PQ and CQ at 186.6 °C, which is identical to that of the phospholipid. However, no crystallinity changes were detected through powder X-ray diffraction analysis. Moreover, PQ, with either single or dual loading, produced the higher calcein release profiles from the liposomes than that of CQ. The dual loading of PQ and CQ tends to interact with the polar head group of the phosphatidylcholine bilayer membrane resulted in an increase in water permeability of the liposomes.

The Kinetics of Initiated Oxidation of Phosphatidylcholine Liposomes with Introduced Aloe Extracts and Determination of their Antioxidant Activity

The Kinetics of Initiated Oxidation of Phosphatidylcholine Liposomes with Introduced Aloe Extracts and Determination of their Antioxidant Activity

The Comparison of In Vitro Photosensitizing Efficacy of Curcumin-Loaded Liposomes Following Photodynamic Therapy on Melanoma MUG-Mel2, Squamous Cell Carcinoma SCC-25, and Normal Keratinocyte HaCaT Cells.

The research focused on the investigation of curcumin encapsulated in hydrogenated soy phosphatidylcholine liposomes and its increased photoactive properties in photodynamic therapy (PDT). The goal of this study was two-fold: to emphasize the role of a natural photoactive plant-based derivative in the liposomal formulation as an easily bioavailable, alternative photosensitizer (PS) for the use in PDT of skin malignancies. Furthermore, the goal includes to prove the decreased cytotoxicity of phototoxic agents loaded in liposomes toward normal skin cells. Research was conducted on melanoma (MugMel2), squamous cell carcinoma (SCC-25), and normal human keratinocytes (HaCaT) cell lines. The assessment of viability with MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) evaluated cell death after exposure to blue light irradiation after 4 h of pre-incubation with free and encapsulated curcumin. Additionally, the wound healing assay, flow cytometry, and immunocytochemistry to detect apoptosis were performed. The malignant cells revealed increased phototoxicity after the therapy in comparison to normal cells. Moreover, liposome curcumin-based photodynamic therapy showed an increased ratio of apoptotic and necrotic cells. The study also demonstrated that nanocurcumin significantly decreased malignant cell motility following PDT treatment. Acquired results suggest that liposomal formulation of a poor soluble natural compound may improve photosensitizing properties of curcumin-mediated PDT treatment in skin cancers and reduce toxicity in normal keratinocytes.

Binding of liposomes composed of phosphatidylcholine to scavenger receptor class B type 1 and its modulation by phosphatidic acid in HEK293T cells

In this study, we developed a method to analyze liposomal binding to a cell membrane receptor using fluorescence-labeled liposomes and demonstrated that scavenger class B type 1 (SR-B1) plays a crucial role in binding of liposomes containing phosphatidylcholine (PC) to HEK293T cell membrane and phosphatidic acid (PA) can modulate it. Site-directed mutagenesis of SR-B1 revealed that S112F and T175A mutations in its ectodomain abrogated binding and endocytosis of PC liposomes in HEK293T cells. K151A and K156A mutations attenuated their binding and endocytosis too. Although the effects of mutations on binding and endocytosis were similar between PC liposomes and PC/PA and PA liposomes, SR-B1 dependency appeared to be PC > PC/PA > PA liposomes. Our data indicate that (i) nanoparticles including high-density lipoprotein (HDL), silica, and liposomes bind to a common or close site of SR-B1, and (ii) PC/PA and PA liposomes bind not only to SR-B1 but also other receptor(s) in HEK293T cells. In addition, PC/PA liposomes induced lipid droplet (LD) formation in HEK293T cells more than PC liposomes. Treatment of HEK293T cells with SR-B1 siRNA suppressed PC/PA liposome-induced LD formation. Taken together, our results demonstrate that SR-B1 plays an essential role in binding PC-containing liposomes and the subsequent induction of cellular responses, while PA can modulate them.

Proteomic analysis reveals differential responses of Listeria monocytogenes to free and nanoencapsulated nisin

The ability of Listeria monocytogenes grow on ready-to-eat food is a major concern in food safety. Natural antimicrobials, such as nisin, can be used to control this pathogen, but the increasing reports of nisin tolerance and resistance make necessary novel approaches to increase its effectiveness, such as encapsulation. The goal of this study was to investigate how L. monocytogenes ATCC7644 regulates and shapes its proteome in response to sublethal doses of nisin and nisin-loaded phosphatidylcholine liposomes (lipo-nisin), compared to untreated cells growing under optimal conditions. Total proteins were extracted from L. monocytogenes cells treated for 1 h with free and lipo-nisin. As result, of 803 proteins that were initially identified, 64 and 53 proteins were differentially upregulated and downregulated respectively, in the treatments with nisin and lipo-nisin. Changes of Listeria proteome in response to treatments containing nisin were mainly related to ATP-binding cassette (ABC) transporter systems, transmembrane proteins, RNA-binding proteins and diverse stress response proteins. Some of the proteins uniquely detected in samples treated with free nisin were the membrane proteins SecD, Lmo1539 and the YfhO enzyme, which are related to translocation of L. monocytogenes virulence factors, activation of the LiaR-mediated stress defense and glycosylation of wall teichoic acid, respectively. The L. monocytogenes treated with liposome encapsulated nisin showed no expression of some stress response factors as compared with the free nisin, suggesting a reduction of stress mediated response and production of nisin-resistance factors by exposure to encapsulated nisin.

Changes in the Free Fatty-Acid Profile in the Liver and Brain of Mice Receiving Nanolipid Complexes

Gas chromatography was used to study changes in the fatty-acid (FA) profile of the liver and brain lipids in six groups of mice that received nanoliposomal complexes of different compositions added to drinks that replaced water in a long-term diet (3 months). The components of the six nanoliposomal types included clove essential oil (CEO), fish oil (FO), and sodium caseinate (Na-Cas), along with phosphatidylcholine (PC). It was found that compound nanoliposomal complexes that contain both essential polyunsaturated free fatty acids (PUFAs) and CEO natural antioxidant, along with Na-Cas food protein, can modify the liver and brain lipid profiles and increase the amount of decosahexaenoic acid (DHA) while considerably reducing the Σ omega-6/Σ omega-3 PUFA ratio. Such changes may increase resistance to inflammatory processes and reduce the risk of cancer and neuropsychiatric diseases. The obtained data may be used to develop new PUFA delivery systems based on PC liposomes.

Preparation and Characterization of Two Different Liposomal Formulations with Bioactive Natural Extract for Multiple Applications

Liposomes continue to attract great interest due to their increased bioavailability in the body and because the substances encapsulated are protected while maintaining their effectiveness. The aim of this study is to obtain “giant” liposomes by lipid film hydration using a preparation formula with two different phospholipids, phosphatidylcholine (PC) and phosphatidylserine (PS). Firstly, the macro- and microscopic characterization, total phenols content and antioxidant capacity of the plant Stellaria media (L.) Vill. were assessed. Then, Stellaria media (L.) Vill. extract was encapsulated in both formulations (PCE and PSE) and the liposomes were characterized according to their morphology, size distribution and Zeta potential using optical microscopy and dynamic light scattering. The encapsulation efficiency (EE%) was determined using the Folin–Ciocalteu method and the values of both formulations were compared. PC and PCE liposomes with a diameter between 712 and 1000 nm and PS and PSE liposomes with a diameter between 58 and 1000 nm were obtained. The values EE% of Stellaria media (L.) Vill. extract for PCE and PSE were 92.09% and 84.25%, respectively.

Effect of Selected Anionic and Cationic Drugs Affecting the Central Nervous System on Electrical Properties of Phosphatidylcholine Liposomes: Experiment and Theory.

Interactions between phospholipid membranes and selected drugs affecting the central nervous system (CNS) were investigated. Small, unilamellar liposomes were used as biomimetic cell membrane models. Microelectrophoretic experiments on two-component liposomes were performed using the electrophoretic light scattering technique (ELS). The effect of both positively (perphenazine, PF) and negatively (barbituric acid, BA) charged drugs on zwitterionic L-α-phosphatidylcholine (PC) membranes were analyzed. Experimental membrane surface charge density (δ) data were determined as a function of pH. Quantitative descriptions of the adsorption equilibria formed due to the binding of solution ions to analyzed two-component membranes are presented. Binding constants of the solution ions with perphenazine and barbituric acid-modified membranes were determined. The results of our research show that both charged drugs change surface charge density values of phosphatidylcholine membranes. It can be concluded that perphenazine and barbituric acid are located near the membrane surface, interacting electrostatically with phosphatidylcholine polar heads.

Towards the Development of Long Circulating Phosphatidylserine (PS)- and Phosphatidylglycerol (PG)-Enriched Anti-Inflammatory Liposomes: Is PEGylation Effective?

The anionic phospholipids (PLs) phosphatidylserine (PS) and phosphatidylglycerol (PG) are endogenous phospholipids with anti-inflammatory and immunomodulatory activity. A potential clinical use requires well-defined systems and for several applications, a long circulation time is desirable. Therefore, we aimed the development of long circulating liposomes with intrinsic anti-inflammatory activity. Hence, PS- and PG-enriched liposomes were produced, whilst phosphatidylcholine (PC) liposomes served as control. Liposomes were either formulated as conventional or PEGylated formulations. They had diameters below 150 nm, narrow size distributions and composition-dependent surface charges. Pharmacokinetics were assessed non-invasively via in vivo fluorescence imaging (FI) and ex vivo in excised organs over 2 days. PC liposomes, conventionally formulated, were rapidly cleared from the circulation, while PEGylation resulted in prolongation of liposome circulation robustly distributing among most organs. In contrast, PS and PG liposomes, both as conventional or PEGylated formulations, were rapidly cleared. Non-PEGylated PS and PG liposomes did accumulate almost exclusively in the liver. In contrast, PEGylated PS and PG liposomes were observed mainly in liver and spleen. In summary, PEGylation of PS and PG liposomes was not effective to prolong the circulation time but caused a higher uptake in the spleen.

Ascorbyl palmitate effects on the stability of curcumin-loaded soybean phosphatidylcholine liposomes

The effect of ascorbyl palmitate (AP) on the physical stability of soy phosphatidylcholine (SPC) liposomes and the retention rate of curcumin loaded into SPC liposomes enriched with different concentrations of AP was studied. Results showed that the transmittance, stability coefficient and particle size of liposomes were all influenced by the addition of AP. The highest stability of AP-stabilized liposomes was achieved when the mass ratio of SPC to AP was at 50:5 by increasing the surface charge, as indicated by an increase in ζ-potential from −15.1 mV (pure liposome) to −35.4 mV (AP-enriched SPC). Beyond this ratio, excessive AP addition was unfavorable to the stability of liposomes. Also at this 10% ratio, small angle X-ray scattering and differential scanning calorimetry results showed the strongest interaction between AP and the SPC liposomes, with the altering of the bilayer structure and the main phase transition temperature. Atomic force microscopy results showed that the addition of AP did not obviously change the vesicle microstructure but increased the vesicle height and contact angle. When curcumin was loaded into AP-enriched liposomes as a model bioactive, the best storage stability was observed in the liposome formulation with 10% added AP, which correlated well with the physical stability of the system. These results open up the possibility of AP-modified liposomes being developed as a multifunctional formulation for encapsulating and delivering nutraceuticals.

Self-assembled ultrasmall silver nanoclusters on liposome for topical antimicrobial delivery

Silver nanomaterials represent one of the most efficient and promising strategies for bacterial disinfection considering the growing resistance threats of conventional antibiotics. Ultrasmall silver nanocluster (Ag NC) is the most exciting next generation silver based nanomaterial with intriguing physiochemical properties of sub-2 nm core size and abundant active Ag+ ions, while the study of Ag NC based antibiotics is still in its infancy. The current applications of Ag NCs under physiological condition are susceptibly hindered by spontaneous aggregation and silver oxidation, resulting in the loss of antimicrobial efficiency. In this work, a core-shell structured Ag NC based nanocomposite was synthesized through the encapsulation of Ag NCs in the phosphatidylcholine liposomes (Ag NC@liposome). This liposomal Ag NC was demonstrated as a broad-spectrum antimicrobial agent with killing efficiency >99.99 % and wide pH range tolerance of pH = 5‒9. An in-depth investigation shows that the core-shell construct of this nanocomposite is essential for controlled release of Ag+ ions and sustainable reactive oxygen species (ROS) production. More importantly, this nanocomposite possesses minimum cytotoxicity on mammalian cells and can be successfully applied for wound disinfection in vivo. To our knowledge, this is the first example of Ag NC based liposomal formulation. This sophisticated design would be indicative to the research and development of Ag NCs in portable bandages and implantable devices for topical antimicrobial delivery.

Screening and enhancement of the antimicrobial activity of some plant oils using liposomes as nanoscale carrier

BackgroundLiposomes have the ability to enclose hydrophilic or lipophilic materials. Bioactive macromolecules become more stable when they are entrapped within liposomes resisting environmental changes, allowing maintenance of the antimicrobial molecules and increasing their effectiveness and constancy thus can be used for food preservation. The aim of this study was to screen food samples for microbial contamination and to examine the antimicrobial activity of selected six ready-made plant oils which were; clove, black seed, thyme, garlic, rosemary and green tea against the isolated microbes from food samples and other selected microbes. Also to examine the possible enhancement of the antibacterial property of clove oil and tetracycline versus Escherichia coli when they were encapsulated into distearoyl phosphatidylcholine (DSPC) liposomes as a nanoscale carriers. Results of the antimicrobial action measured by minimum inhibitory concentration revealed that all six oils had antimicrobial action when facing at least one of the tested microbes. However only clove oil could inhibit the growth of all tested microbes. Moreover encapsulation of clove oil into DSPC liposomes enhanced its antibacterial action by 10 times when examined to inhibit the growth of E. coli. Also the antibacterial activity of liposome encapsulated tetracycline was improved by 8 times. Results of characterization of formulated clove oil liposomes by measuring their Zeta potential and their sizes implying that clove oil might be enclosed within the hydrophobic portion of the two layers of the liposome. Analyzing data of Fourier Transform Infrared Spectroscopy showed that clove oil was detected in the interfacial area of the liposome. Analyzing results of Differential scanning calorimetry and measuring phase transitions suggested that liposomes encapsulating clove oil had a membrane fluidization effect.ConclusionSome plant oils like clove has antimicrobial activity which enhanced with liposomal encapsulation and thus reduces the needed concentration to give the desired actions.