Natural Phospholipids Research Articles

A Synthetic Phospholipid Derivative Mediates Ion Transport Across Lipid Bilayers

Inspired by the natural phospholipid structures for cell membrane, a synthetic phospholipid LC with an ion recognition group benzo-18-crown-6 (B18C6) moiety was prepared which has been demonstrated to be able to transport ions across the lipid bilayers. Fluorescent vesicle assay shows that LC has an excellent transport activity, and the EC50 value for K+ is 11.2 μM. The voltage clamp measurement exhibits regular square-like current signals with considerably long opening times, which indicates that LC achieves efficient ion transport through a channel mechanism and its single channel conductivity is 17 pS. Both of the vesicle assay and patch clamp tests indicate that LC has selectivity for Rb+, whose ionic radius is larger than the cavity of crown ether. It suggests that the sandwich interaction may play a key role in the ion transport across lipid bilayers. All these results help us to speculate that LC transports ions via a channel mechanism with a tetrameric aggregate as the active structure. In addition, LC had obvious toxicity to HeLa cells, and the IC50 was 100.0 μM after coculture for 36 h. We hope that this simple synthetic phospholipid will offer novel perspectives in the development of more efficient and selective ion transporters.

Insights Into Exosomal Non-Coding RNAs Sorting Mechanism and Clinical Application.

Exosomes are natural nanoscale bilayer phospholipid vesicles that can be secreted by almost all types of cells and are detected in almost all types of body fluids. Exosomes are effective mediators of cell–cell signaling communication because of their ability to carry and transfer a variety of bioactive molecules, including non-coding RNAs. Non-coding RNAs have also been found to exert strong effects on a variety of biological processes, including tumorigenesis. Many researchers have established that exosomes encapsulate bioactive non-coding RNAs that alter the biological phenotype of specific target cells in an autocrine or a paracrine manner. However, the mechanism by which the producer cells package non-coding RNAs into exosomes is not well understood. This review focuses on the current research on exosomal non-coding RNAs, including the biogenesis of exosomes, the possible mechanism of sorting non-coding RNAs, their biological functions, and their potential for clinical application in the future.

Structural Changes of the Lipid Model Systems in the Presence of Enzymes or Silver Nanoparticles

This work aimed to study the interaction of silver nanoparticles (AgNP) and lipases with models of biological membranes based on natural phospholipid and cholesterol. The crude phosphatidylcholine from egg yolk (PCe1) and synthetic cholesterol (Chol) were obtained from Sigma-Aldrich. Porcine pancreatic lipase (PPL) was obtained by purification from the hog pancreas. AgNP dispersion was prepared by the well-known citrate method. Measurement of surface tension (ST) was carried out using a BPA-1P device. The equilibrium surface tension (eST) was obtained by calculating the ST-time isotherms using the ADSA program. The particle sizes were determined by the dynamic light scattering method. An addition of AgNPs led to a pronounced decrease in both ST and eST (whereas almost no changes occurred by lipase addition), and AgNPs destructed the large lipid particles. The average lipid particle diameter values changed drastically, whereas the effective particle diameter values were almost the same by lipase addition. Thus, the interactions of AgNPs or lipase with the mixture of natural phospholipid and cholesterol have had entirely different features. These effects are interesting for modeling the interactions of inorganic and organic compounds with biological membranes.

Simultaneous action of microbial phospholipase C and lipase on model bacterial membranes – Modeling the processes crucial for bioaugmentation

Bioaugmentation is a promising method of the remediation of soils polluted by persistent organic pollutants (POP). Unfortunately, it happens frequently that the microorganisms inoculated into the soil die out due to the presence of enzymes secreted by autochthonous microorganisms. Especially destructive are here phospholipases C (PLC) and lipases which destruct the microorganism's cellular membrane. The composition of bacterial membranes differs between species, so it is highly possible that depending on the membrane constitution some bacteria are more resistant to PLCs and lipases than other. To shed light on these problems we applied phospholipid Langmuir monolayers as model microbial membranes and studied their interactions with α-toxin (model bacterial PLC) and the lipase isolated from soil fungus Candida rugosa. Membrane phospholipids differing in their headgroup (phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols and cardiolipins) and in their tail structure were applied. The monolayers were characterized by the Langmuir technique, visualized by Brewster angle microscopy, and the packing mode of the phospholipid molecules was verified by the application of the diffraction of synchrotron radiation. We also studied the mutual miscibility of diacylglycerols and the native phospholipids as their interaction is crucial for the understanding of the PLC and lipase activity. It turned out that all the investigated phospholipid classes can be hydrolyzed by PLC; however, they differ profoundly in the hydrolysis degree. Depending on the effects of the initial PLC action and the mutual organization of the diacylglycerol and phospholipid molecules the lipase can ruin the model membranes or can be completely neutral to them.

Phosphatidylinositol Stabilizes Fluid-Phase Liposomes Loaded with a Melphalan Lipophilic Prodrug.

Previously, a liposomal formulation of a chemotherapeutic agent melphalan (Mlph) incorporated in a fluid lipid bilayer of natural phospholipids in the form of dioleoylglyceride ester (MlphDG) was developed and the antitumor effect was confirmed in mouse models. The formulation composed of egg phosphatidylcholine (ePC), soybean phosphatidylinositol (PI), and MlphDG (8:1:1, by mol) showed stability in human serum for at least 4–5 h. On the contrary, replacing PI with pegylation of the liposomes, promoted fast dissociation of the components from the bilayer. In this work, interactions of MlphDG-liposomes with the most abundant plasma protein—albumin—in function of the presence of PI in the formulation were explored using Fourier transform infrared spectroscopy. The release of MlphDG from the liposomes was studied by asymmetrical flow field-flow fractionation (AF4) using micelles formed by a polyethylene glycol conjugate with phosphatidylethanolamine to mimic the physiological lipid sink like lipoproteins. Our results show that PI actually protects the membrane of MlphDG-liposomes from the protein penetration, presumably due to pairing between the positively charged MlphDG and negatively charged PI, which compensates for the heterogeneity of the lipid bilayer. The AF4 technique also evidences high stability of the formulation as a drug carrier.

Targeted Delivery of Combination Therapeutics Using Monoclonal Antibody 2C5-Modified Immunoliposomes for Cancer Therapy.

To develop immunoliposomes modified with monoclonal cancer-specific antibody (mAb) 2C5 and co-loaded with a combination of two chemotherapeutics, in order to simultaneously target bulk cancer cells using paclitaxel and cancer stem cells (CSCs) using salinomycin to prevent cancer growth and metastases. Breast cancer cells (MDA-MB-231 and/or SK-BR-3) were chosen as models for all in vitro testing. Liposomes composed of natural phospholipids co-loaded with salinomycin and paclitaxel were prepared and physically characterized. Immunoliposomes modified with mAb 2C5 coupled to polymeric conjugate were prepared and characterized for specific targeting. Wound healing assay was performed using the combination of free drugs in vitro. In vitro studies on cellular interaction and uptake were followed by holographic imaging to study cell-killing, cell-division and proliferation inhibiting effects of the formulation. Ex-vivo study on hemolysis was investigated to check possible toxicity of the formulation. Physical characterization of the liposomes showed stable nanoparticles of consistent and desirable size range (170-220nm), zeta potential (-13mV to - 20mV), polydispersity indices (<0.2) and drug encapsulation efficiencies (~150μg per ml for salinomycin, ~210μg/ml for paclitaxel and 1:1 for combination drug loaded liposomes). Combination therapy strongly affected cancer cell proliferation as shown by significant diminishing of artificial gap closure at the wound site on MDA-MB-231 cells in culture using wound healing assay. Quantitation of changes in wound widths showed ~219μm for drug combination, ~104μm for only paclitaxel, and ~ 7μm for only salinomycin treatments. Statistically significant increase in cellular interaction and specific uptake of the targeted drug co-loaded liposomal nanopreparation (p value ≤ 0.05) by MDA-MB-231 and SK-BR-3 cells confirmed the effectiveness of the approach. Holographic imaging using MDA-MB-231 cells produced visible increase in cell-killing, proliferation and division in vitro. Ex-vivo experimentation showed reduced hemolysis correlating with low toxicity in athymic nude mice model. The results demonstrated the enhanced therapeutic efficacy of a combination of salinomycin and paclitaxel delivered by mAb 2C5-modified liposomal preparation in cancer therapy.

Engineering the liposomal formulations from natural peanut phospholipids for pH and temperature sensitive release of folic acid, levodopa and camptothecin

The present study demonstrates the extraction and identification of phospholipids (PLs) from peanut seed for formulation of liposomes for pH and thermo-sensitive delivery and release of folic acid (FA), levodopa (DOPA) and, camptothecin (CPT). The TLC, FTIR and GC–MS based characterization of extracted peanut PLs showed phosphatidylethanolamine, cardiolipin and phosphatidic acid as major PLs and palmitic acid and oleic acid as major fatty acids. Liposomes (LSMs) of size 1–2 μm formulated by optimized thin-film hydration method were found to entrap FA, DOPA and CPT with 58, 61.4 and 52.12% efficiency, respectively with good stability. The effect of external stimuli like pH and temperature on the release pattern of FA, DOPA and CPT indicated that FA was optimally released at pH 10 and 57 °C, DOPA at pH 2 and 37 °C, while CPT was best released at pH 6 and 47 °C. When tested for the in vitro activity, DOPA released by DOPA@LSMs showed lower toxicity to 3T3 than to SH-SY5Y cells. Similarly, CPT released by CPT@LSMs showed remarkable anticancer activity against MCF-7 cells with an IC50 value of 17.99 μg/mL. Thus peanut PLs can be efficiently used for liposomal formulations for pH and thermo-sensitive release of drugs.

Novel bone repairing scaffold consisting of bone morphogenetic Protein-2 and human Beta Defensin-3

BackgroundSynthetic biomaterials assist in modulating the vascular response in an injured bone by serving as delivery vehicles of pro-angiogenic molecules to the site of injury or by serving as mimetic platforms which offer support to cell growth and proliferation.MethodsThis study applied natural phospholipid modified protein technologies together with low temperature three-dimensional printing technology to develop a new model of three-dimensional artificial bone scaffold for potential use in repairing body injuries. The focus was to create a porous structure (PS) scaffold of two components, Bone Morphogenetic Protein-2 and Human Beta Defensin-3 (BMP2 and hBD3), which can synchronously realize directional bone induction, angiogenesis and postoperative antibacterial effects. BMP2 induces osteogenesis, whereas hBD3 is antibacterial.ResultsOur data showed that in the BMP2-hBD3-PS or hBD3-PS scaffolds, BMP2 had a slow-release rate of about 40% in 30 days, ensuring that BMP2 could penetrate into stem cells for osteogenic differentiation for a long time. The scaffolds promoted cell growth when in combination with BMP2, thus showing its importance in promoting cell growth. Alkaline Phosphatase (ALP) staining showed that the ALP content of BMP2-hBD3-PS and BMP2-PS had a significant increase in samples that contained BMP2, thus showing that these scaffolds promoted osteogenic differentiation. In all the constructs that had hBD3, they displayed antibacterial properties with hBD3, having a slow release of about 35% in 30 days, thus ensuring they provided protection.ConclusionBased on this study, the 3D printed BMP2 scaffolds show a great potential for the development of biodegradable bone implants.Level of evidenceLevel II, experimental comparative design.

Membrane-destabilizing ionizable phospholipids for organ-selective mRNA delivery and CRISPR-Cas gene editing.

Endosomal escape remains a fundamental barrier hindering advancement of nucleic acid therapeutics. Taking inspiration from natural phospholipids that comprise biological membranes, we report the combinatorial synthesis of multi-tailed ionizable phospholipids (iPhos) capable of delivering mRNA or mRNA/sgRNA for gene editing in vivo. Optimized iPhos lipids are composed of one pH-switchable zwitterion and three hydrophobic tails, which adopt a cone shape in endosomal acidic environment to facilitate membrane hexagonal transformation and subsequent cargo release from endosomes. Structure-activity relationships reveal that iPhos chemical structure can control in vivo efficacy and organ selectivity. iPhos lipids synergistically function with various helper lipids to formulate multi-component lipid nanoparticles (iPLNPs) for Selective Organ Targeting (SORT). Zwitterionic, ionizable cationic, and permanently cationic helper lipids enable tissue-selective mRNA delivery and CRISPR/Cas9 gene editing in spleen, liver, and lungs (respectively) following intravenous administration. This rational design of functional phospholipids demonstrates significant value for gene editing research and therapeutic applications.

Lyso-phosphatidylethanolamine primes the plant immune system and promotes basal resistance against hemibiotrophic pathogens

BackgroundLyso-phosphatidylethanolamine (LPE) is a natural phospholipid that functions in the early stages of plant senescence. Plant innate immunity and early leaf senescence share molecular components. To reveal conserved mechanisms that link-up both processes, we tried to unravel to what extent LPE coordinates defense response and by what mode of action.ResultWe found that LPE-treatment induces signaling and biosynthesis gene expression of the defensive hormone salicylic acid (SA). However, jasmonic acid and ethylene triggered gene induction levels are indistinguishable from the control. In accordance with gene induction for SA, oxidative stress, and reactive oxygen species (ROS) production, we detected raised in-situ hydrogen peroxide levels following LPE-application. Yet, ROS-burst assays of LPE-pretreated plants revealed a reduced release of ROS after PAMP-administration suggesting that LPE interferes with an oxidative burst. Our data refer to a priming effect of LPE on SA/ROS-associated genomic loci that encode pivotal factors in early senescence and considerably improve plant basal immunity. Thus, we challenged Arabidopsis thaliana with the hemibiotrophic pathogen Pseudomonas syringae. Consistently, we found an increased resistance in the LPE-pretreated Arabidopsis plants compared to the mock-pretreated control.ConclusionsOur results underscore a beneficial effect of LPE on plant innate immunity against hemibiotrophs. Given the resistance-promoting effect of exogenously applied LPE, this bio-agent bears the potential of being applied as a valuable tool for the genetic activation of defense-associated traits.

A promiscuous archaeal cardiolipin synthase enables construction of diverse natural and unnatural phospholipids

Cardiolipins (CL) are a class of lipids involved in the structural organization of membranes, enzyme functioning, and osmoregulation. Biosynthesis of CLs has been studied in eukaryotes and bacteria, but has been barely explored in archaea. Unlike the common fatty acyl chain–based ester phospholipids, archaeal membranes are made up of the structurally different isoprenoid-based ether phospholipids, possibly involving a different cardiolipin biosynthesis mechanism. Here, we identified a phospholipase D motif–containing cardiolipin synthase (MhCls) from the methanogen Methanospirillum hungatei. The enzyme was overexpressed in Escherichia coli, purified, and its activity was characterized by LC-MS analysis of substrates/products. MhCls utilizes two archaetidylglycerol (AG) molecules in a transesterification reaction to synthesize glycerol-di-archaetidyl-cardiolipin (Gro-DACL) and glycerol. The enzyme is nonselective to the stereochemistry of the glycerol backbone and the nature of the lipid tail, as it also accepts phosphatidylglycerol (PG) to generate glycerol-di-phosphatidyl-cardiolipin (Gro-DPCL). Remarkably, in the presence of AG and PG, MhCls formed glycerol-archaetidyl-phosphatidyl-cardiolipin (Gro-APCL), an archaeal-bacterial hybrid cardiolipin species that so far has not been observed in nature. Due to the reversibility of the transesterification, in the presence of glycerol, Gro-DPCL can be converted back into two PG molecules. In the presence of other compounds that contain primary hydroxyl groups (e.g., alcohols, water, sugars), various natural and unique unnatural phospholipid species could be synthesized, including multiple di-phosphatidyl-cardiolipin species. Moreover, MhCls can utilize a glycolipid in the presence of phosphatidylglycerol to form a glycosyl-mono-phosphatidyl-cardiolipin species, emphasizing the promiscuity of this cardiolipin synthase that could be of interest for bio-catalytic purposes.

S1P induces proliferation of pulmonary artery smooth muscle cells by promoting YAP-induced Notch3 expression and activation

Sphingosine-1-phosphate (S1P), a natural multifunctional phospholipid, is highly increased in plasma from patients with pulmonary arterial hypertension and mediates proliferation of pulmonary artery smooth muscle cells (PASMCs) by activating the Notch3 signaling pathway. However, the mechanisms underpinning S1P-mediated induction of PASMCs proliferation remain unclear. In this study, using biochemical and molecular biology approaches, RNA interference and gene expression analyses, 5′-ethynyl-2′-deoxyuridine incorporation assay, and 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, we demonstrated that S1P promoted the activation of signal transducers and activators of transcription 3 (STAT3) through sphingosine-1-phosphate receptor 2 (S1PR2), and subsequently upregulated the expression of the microRNA miR-135b, which further reduced the expression of E3 ubiquitin ligase β-transduction repeat-containing protein and led to a reduction in yes-associated protein (YAP) ubiquitinated degradation in PASMCs. YAP is the core effector of the Hippo pathway and mediates the expression of particular genes. The accumulation of YAP further increased the expression and activation of Notch3 and ultimately promoted the proliferation of PASMCs. In addition, we showed that preblocking S1PR2, prior silencing of STAT3, miR-135b, or YAP, and prior inhibition of Notch3 all attenuated S1P-induced PASMCs proliferation. Taken together, our study indicates that S1P stimulates PASMCs proliferation by activation of the S1PR2/STAT3/miR-135b/β-transduction repeat-containing protein/YAP/Notch3 pathway, and our data suggest that targeting this cascade might have potential value in ameliorating PASMCs hyperproliferation and benefit pulmonary arterial hypertension.

Methods for obtaining liposomal systems to be used in the food industry

Currently encapsulation of food ingredients using liposomal systems formed by natural phospholipids is of greatest interest for food industry. One of the advantages of encapsulation using liposomal systems is the amphiphilicity of the phospholipids that form them, which allows both hydrophilic and hydrophobic ingredients to be encapsulated, while most other encapsulating agents can only encapsulate hydrophilic ingredients. The article reviews the existing methods for obtaining liposomal systems. It has been shown that the most common classical method for obtaining liposomes, namely, the method of a thin film hydration does not allow obtaining liposomal dispersions that are uniform in shape and size. Moreover, this method requires a large consumption of organic solvents. Physical methods have been considered that make it possible to obtain uniform in shape and size liposome dispersions, in particular, ultrasonic treatment, extrusion under pressure, and microfluidization. The advantages and disadvantages of these methods have been presented. Alternative methods of obtaining liposomal systems without the use of toxic organic solvents and detergents have been considered. It should be noted that development of methods for producing liposomal systems that could be implemented on an industrial scale for the intensive introduction of these systems in food technology is now becoming increasingly important.

Physical stability of microliposomes in bene (Pistacia atlantica) oil with different formulations

Bene oil (pistacia atlantica), as a plant source, is rich in phenolic and tocopherol compounds and has significant antioxidant, therapeutic and antimicrobial effects. Encapsulation of hydrophobic compounds in liposome system is an ideal solution for protecting them against destruction during storage. An important advantage of liposomes is the encapsulation of hydrophilic, hydrophobic and amphiphilic compounds by using natural phospholipids, such as lecithin, with beneficial effects. The aim of this study is to encapsulate the bene kernel oil in the form of microliposomes. For this purpose, the effect of composition of liposomes based on lecithin and cholesterol was studied using the Mozafari method. Liposomes are prepared using lecithin and cholesterol in the ratios of 60:0, 50:10, 40:20 and 30:30. Particle size, size distribution, zeta potential and encapsulation efficiency were charac-terised. According to the result, the size of liposomes was dependent on their composition, but the wasaffected significantly affected by adding cholesterol (P &lt; 0.05). Average diameter of the particles was between 4 and 9 µm. Liposome with a ratio of 40:20 had the smallest size. By applying cholesterol, zeta potential increased from 16.4 mV to 32.39 mV, which indicates electrostatic stability of liposomes. In general, with encapsulation efficiency of 84.33%, the ratio of 40:20 is considered as an ideal concentration in the formulation of microliposomes. Based on the results, bene oil-loaded liposomes with a lecithin:cholesterol formulation ratio of :as 40:20 was chosen as an optimal formulation because of its smaller particle size, higher zeta potential and suitable stability, which can be used in trapping, delivering and releasing hydrophilic, adipose-friendly and amphiphilic compounds (dual-friendly).

Physical stability of microliposomes in bene (Pistacia atlantica) oil with different formulations

Bene oil (pistacia atlantica), as a plant source, is rich in phenolic and tocopherol compounds and has significant antioxidant, therapeutic and antimicrobial effects. Encapsulation of hydrophobic compounds in liposome system is an ideal solution for protecting them against destruction during storage. An important advantage of liposomes is the encapsulation of hydrophilic, hydrophobic and amphiphilic compounds by using natural phospholipids, such as lecithin, with beneficial effects. The aim of this study is to encapsulate the bene kernel oil in the form of microliposomes. For this purpose, the effect of composition of liposomes based on lecithin and cholesterol was studied using the Mozafari method. Liposomes are prepared using lecithin and cholesterol in the ratios of 60:0, 50:10, 40:20 and 30:30. Particle size, size distribution, zeta potential and encapsulation efficiency were characterised. According to the result, the size of liposomes was dependent on their composition, but the wasaffected significantly affected by adding cholesterol (P &lt; 0.05). Average diameter of the particles was between 4 and 9 µm. Liposome with a ratio of 40:20 had the smallest size. By applying cholesterol, zeta potential increased from 16.4 mV to 32.39 mV, which indicates electrostatic stability of liposomes. In general, with encapsulation efficiency of 84.33%, the ratio of 40:20 is considered as an ideal concentration in the formulation of microliposomes. Based on the results, bene oil-loaded liposomes with a lecithin: cholesterol formulation ratio of :as 40:20 was chosen as an optimal formulation because of its smaller particle size, higher zeta potential and suitable stability, which can be used in trapping, delivering and releasing hydrophilic, adipose-friendly and amphiphilic compounds (dual-friendly).

Characterization of an anionic membrane mimetic with natural phospholipid content and magnetic orienting capabilities

The cellular membrane is a highly complex and dynamical structure, with variable and inhomogeneous composition, which makes detailed structural studies a very difficult task. 2H-NMR has become one of the most useful tools for many of such studies, however this requires the use of simpler structures that behave as close as possible to the cellular membrane, i.e. membrane mimetics. In this article we present a new anionic nematic lyotropic liquid crystal, with an important content of a natural mixture of phospholipids isolated from soybean, which can be employed as membrane mimetic. The capability of the mesophase to spontaneously orient when exposed to an external magnetic field, enables it for studies about distribution, dynamics and mobility of mesophase components, as well as dissolved substrates, employing 2H-NMR. A 2H-NMR characterization of the mimetic is performed by using different deuterated probes. To validate its permeability properties as membrane, the permeating capability of Benzocaine and the inability of Levodopa to do so were tested. For an atomic detailed characterization of both, the new mimetic and the process of crossing the interface, we also present a molecular dynamics simulation calibrated to reproduce experimental 2H-NMR results.

Oleosomes Encapsulating Sildenafil Citrate as Potential Topical Nanotherapy for Palmar Plantar Erythrodysesthesia with High Ex vivo Permeation and Deposition.

Palmar plantar erythrodysesthesia (PPE) is a commonly reported skin toxicity of chemotherapeutic agents that significantly affects patients' quality of life. PPE is described as inflammation, swelling, and even cracks and ulcers in the skin of palms and soles of the feet. Conventional treatment includes topical creams, analgesics, or corticosteroids. However, serious cases are not responding to these medications. PPE has been reported to cause drug cessation or dose reduction if not properly treated. Sildenafil citrate (SC) has a well-documented activity in wound healing through improving blood supply to the affected area. However, SC has poor physicochemical properties limiting its transdermal permeation and deposition. This research endeavored to elaborate novel vesicular system with natural components, phospholipids and oleic acid, loaded with sildenafil citrate for topical management of PPE. Sildenafil-loaded oleosomes were prepared using modified ethanol injection method. Optimized oleosomes had nanometric particle size (157.6nm), negative zeta potential (- 85.2 mv), and high entrapment efficiency (95.56%). Ex vivo studies on human skin revealed that oleosomes displayed 2.3-folds higher permeation and 4.5-folds more deposition through the human skin compared to drug suspension. Results endorsed SC oleosomes as suitable topical treatment of PPE providing ameliorated sildenafil permeability in addition to acting as a reservoir for gradual release of the drug. Graphical abstract.

Enzyme-free synthesis of natural phospholipids in water.

All living organisms synthesize phospholipids as the primary constituent of their cell membranes. Enzymatic synthesis of diacylphospholipids requires preexisting membrane-embedded enzymes. This limitation has led to models of early life in which the first cells used simpler types of membrane building blocks and has hampered integration of phospholipid synthesis into artificial cells. Here we demonstrate an enzyme-free synthesis of natural diacylphospholipids by transacylation in water, which is enabled by a combination of ion pairing and self-assembly between lysophospholipids and acyl donors. A variety of membrane-forming cellular phospholipids have been obtained in high yields. Membrane formation takes place in water from natural alkaline sources such as soda lakes and hydrothermal oceanic vents. When formed vesicles are transferred to more acidic solutions, electrochemical proton gradients are spontaneously established and maintained. This high-yielding non-enzymatic synthesis of natural phospholipids in water opens up new routes for lipid synthesis in artificial cells and sheds light on the origin and evolution of cellular membranes.

Polar Head Modified Phospholipids by Phospholipase D-Catalyzed Transformations of Natural Phosphatidylcholine for Targeted Applications: An Overview

This review describes the use of phospholipase D (PLD) to perform the transphosphatidylation of the most common natural phospholipid (PL), phosphatidylcholine (PC) to obtain polar head modified phospholipids with real targeted applications. The introduction of different polar heads with distinctive physical and chemical properties such as charge, polarity and dimensions allows the obtainment of very different PLs, which can be exploited in very diverse fields of application. Moreover, the inclusions of a bioactive moiety in the PL polar head constitutes a powerful tool for the stabilization and administration of active ingredients. The use of this biocatalytic approach allows the preparation of compounds which cannot be easily obtained by classical chemical methods, by using mild and green reaction conditions. PLD is a very versatile enzyme, able to catalyze both the hydrolysis of PC to choline and phosphatidic acid (PA), and the transphosphatidylation reaction in the presence of an appropriate alcohol. The yield of production of the desired product and the ratio with the collateral PA formation is highly dependent on parameters such as the nature and concentration of the alcohol and the enzymatic source. The application of PLD catalyzed transformations for the production of a great number of PLs with important uses in medical, nutraceutical and cosmetic sectors will be discussed in this work.

Organized Hybrid Molecular Films from Natural Phospholipids and Synthetic Block Copolymers: A Physicochemical Investigation.

In the last few years, hybrid lipid-copolymer assemblies have attracted increasing attention as possible two-dimensional (2D) membrane platforms, combining the biorelevance of the lipid building blocks with the stability and chemical tunability of copolymers. The relevance of these systems varies from fundamental studies on biological membrane-related phenomena to the construction of 2D complex devices for material science and biosensor technology. Both the fundamental understanding and the application of hybrid lipid-copolymer-supported bilayers require thorough physicochemical comprehension and structural control. Herein, we report a comprehensive physicochemical and structural characterization of hybrid monolayers at the air/water interface and of solid-supported hybrid membranes constituted by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the block copolymer poly(butadiene-b-ethyleneoxide) (PBD-b-PEO). Hybrid lipid-copolymer supported bilayers (HSLBs) with variable copolymer contents were prepared through spontaneous rupture and fusion of hybrid vesicles onto a hydrophilic substrate. The properties of the thin films and the parent vesicles were probed through dynamic light scattering (DLS), differential scanning calorimetry (DSC), optical ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), and confocal scanning laser microscopy (CSLM). Stable, hybrid lipid/copolymer systems were obtained for a copolymer content of 10-65 mol %. In particular, DSC and CSLM show lateral phase separation in these hybrid systems. These results improve our fundamental understanding of HSLBs, which is necessary for future applications of hybrid systems as biomimetic membranes or as drug delivery systems, with additional properties with respect to phospholipid liposomes.