Beyond Skin Deep: Phospholipid-Based Nanovesicles as Game-Changers in Transdermal Drug Delivery.

Transdermal administration techniques have gained popularity due to their advantages over oral and parenteral methods. Noninvasive, self-administered delivery devices improve patient compliance and control drug release. Transdermal delivery devices struggle with the skin's barrier function. Molecules over 500 Dalton (Da) and ionized compounds don't permeate through the skin. Drug encapsulation in phospholipid-based vesicular systems is the most effective skin delivery technique. Vesicular carriers include bi-layered liposomes, ultra-deformable liposomes, ethanolic liposomes, transethosomes, and invasomes. These technologies enhance skin drug permeation by increasing formula solubilization, partitioning into the skin, and fluidizing the lipid barrier. Phospholipid-based delivery systems are safe and efficient, making them a promising pharmaceutical and cosmeceutical drug delivery technique. Still, making delivery systems requires knowledge about the physicochemical properties of the drug and carrier, manufacturing and process variables, skin delivery mechanisms, technological advances, constraints, and regulatory requirements. Consequently, this review covers recent research achievements addressing the mentioned concerns.

Learning Force Field Parameters from Differentiable Particle-Field Molecular Dynamics.

We develop ∂-HylleraasMD (∂-HyMD), a fully end-to-end differentiable molecular dynamics software based on the Hamiltonian hybrid particle-field formalism, and use it to establish a protocol for automated optimization of force field parameters. ∂-HyMD is templated on the recently released HylleraaasMD software, while using the JAX autodiff framework as the main engine for the differentiable dynamics. ∂-HyMD exploits an embarrassingly parallel optimization algorithm by spawning independent simulations, whose trajectories are simultaneously processed by reverse mode automatic differentiation to calculate the gradient of the loss function, which is in turn used for iterative optimization of the force-field parameters. We show that parallel organization facilitates the convergence of the minimization procedure, avoiding the known memory and numerical stability issues of differentiable molecular dynamics approaches. We showcase the effectiveness of our implementation by producing a library of force field parameters for standard phospholipids, with either zwitterionic or anionic heads and with saturated or unsaturated tails. Compared to the all-atom reference, the force field obtained by ∂-HyMD yields better density profiles than the parameters derived from previously utilized gradient-free optimization procedures. Moreover, ∂-HyMD models can predict with good accuracy properties not included in the learning objective, such as lateral pressure profiles, and are transferable to other systems, including triglycerides.

Elongatibacter sediminis gen. nov., sp. nov., isolated from intertidal sediment, and genomic comparison with all genera in the family Wenzhouxiangellaceae.

A novel slightly halophilic, aerobic, and Gram-stain-negative strain, designated as CH-27T, was isolated during a bacterial resource investigation of intertidal sediment collected from Xiaoshi Island in Weihai, PR China. Cells of strain CH-27T were rod-shaped with widths of 0.3-0.6 µm and lengths of 2.0-11.0 µm. Strain CH-27T grew optimally at 37 °C, pH 7.0 and with 2.0 % (w/v) NaCl. Catalase activity was weakly positive and oxidase activity was positive. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CH-27T was most related to Marinihelvus fidelis KCTC 92639T (93.6 %), followed by Wenzhouxiangella marina MCCC 1K00261T (92.0 %). Based on genome comparisons between strain CH-27T and M. fidelis KCTC 92639T, the average amino acid identity was 63.6 % and the percentage of conserved proteins was 48.3 %. The major cellular fatty acid of strain CH-27T (≥10 %) was iso-C15 : 0 and the sole respiratory quinone was quinone-8. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, and aminophospholipid. The DNA G+C content was 62.7 mol%. Based on comprehensive analysis of its phylogenetic, physiological, biochemical, and chemotaxonomic characteristics, strain CH-27T represents a novel species in a novel genus, for which the name Elongatibacter sediminis gen. nov., sp.nov. is proposed. The type strain is CH-27T (=MCCC 1H00480T=KCTC 8011T).

Reformulating lipid nanoparticles for organ-targeted mRNA accumulation and translation.

Fully targeted mRNA therapeutics necessitate simultaneous organ-specific accumulation and effective translation. Despite some progress, delivery systems are still unable to fully achieve this. Here, we reformulate lipid nanoparticles (LNPs) through adjustments in lipid material structures and compositions to systematically achieve the pulmonary and hepatic (respectively) targeted mRNA distribution and expression. A combinatorial library of degradable-core based ionizable cationic lipids is designed, following by optimisation of LNP compositions. Contrary to current LNP paradigms, our findings demonstrate that cholesterol and phospholipid are dispensable for LNP functionality. Specifically, cholesterol-removal addresses the persistent challenge of preventing nanoparticle accumulation in hepatic tissues. By modulating and simplifying intrinsic LNP components, concurrent mRNA accumulation and translation is achieved in the lung and liver, respectively. This targeting strategy is applicable to existing LNP systems with potential to expand the progress of precise mRNA therapy for diverse diseases.

Exploring the Anticonvulsant Properties of a Celecoxib-Phospholipid Conjugate: Synthesis, Activation, and Evaluation of Cytotoxicity.

BACKGROUND: Epilepsy poses a significant global health challenge, particularly in regions with limited financial resources hindering access to treatment. Recent research highlights neuroinflammation, particularly involving cyclooxygenase-2 (COX-2) pathways, as a promising avenue for epilepsy management. METHODS: This study aimed to develop a Cyclooxygenase-2 inhibitor with potential anticonvulsant properties. A promising drug candidate was identified and chemically linked with phospholipids through docking analyses. The activation of this prodrug was assessed using phospholipase A2 (PLA2)-mediated hydrolysis studies. The conjugate's confirmation and cytotoxicity were evaluated using Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), and Sulphoramide B (SRB) assays. RESULTS: Docking studies revealed that the Celecoxib-Phospholipid conjugate exhibited a superior affinity for PLA2 compared to other drug-phospholipid conjugates. FT-IR spectroscopy confirmed the successful synthesis of the conjugate, while DSC analysis confirmed its purity and formation. PLA2-mediated hydrolysis experiments demonstrated selective activation of the prodrug depending on PLA2 concentration. SRB experiments indicated dose-dependent cytotoxic effects of Celecoxib, phospholipid non-toxicity, and efficient celecoxib-phospholipid conjugation. CONCLUSION: This study successfully developed a Celecoxib-phospholipid conjugate with potential anticonvulsant properties. The prodrug's specific activation and cytotoxicity profile makes it a promising therapeutic candidate. Further investigation into underlying mechanisms and in vivo studies is necessary to assess its translational potential fully.

Arthrobacter horti sp. nov., isolated from mountain soil.

Gram-stain-positive, aerobic, rod-shaped strains, YJM1T and YJM12S, were isolated from Maebong Mountain, Dogok-dong, Gangnam-gu, Seoul, Republic of Korea. Strains YJM1T and YJM12S exhibited growth at 5-35 °C (optimum, 20-30 °C) and pH 6-9 (optimum, pH 7) and in 0-4 % (w/v) NaCl. Strains YJM1T and YJM12S showed highest 16S rRNA gene sequence similarity to the following members of the genus Arthrobacter: A. nanjingensis A33T (98.3 %/98.2 % similarity), A. woluwensis NBRC 107840T (98.2 %/98.1 %), A. humicola KV-653T (97.3 %), A. oryzae KV-651T (97.3 %), and A. globiformis NBRC 12137T (97.2 %). The strains grew well on Reasoner's 2A, nutrient, Mueller-Hinton, yeast-dextrose, and glucose-peptone-meat extract agars. The major polar lipids of strain YJM1T were phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylinositol. The primary respiratory quinone of strain YJM1T was MK-9(H2), and the major fatty acids of strains YJM1T and YJM12S were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, and iso-C16 : 0. The DNA G+C content, based on the whole genome sequence of strain YJM1T, was 68.3 mol%. Average nucleotide identity values and digital DNA-DNA hybridization values between strain YJM1T and the reference strains ranged from 75.0 to 92.7 % and from 21.0 to 65.3 %, respectively. Strain YJM1T exhibited antimicrobial activity against Bacillus subtilis and Escherichia coli. Considering the chemotaxonomic, phenotypic, genotypic, and phylogenetic results, we propose the strain YJM1T represents a novel species in the genus Arthrobacter and suggest the name Arthrobacter horti sp. nov. (type strain YJM1T=KACC 23300T=JCM 36483T).

The Impact of Phospholipid-Based Liquid Crystals' Microstructure on Stability and Release Profile of Ascorbyl Palmitate and Skin Performance.

The drug delivery potential of liquid crystals (LCs) for ascorbyl palmitate (AP) was assessed, with the emphasis on the AP stability and release profile linked to microstructural rearrangement taking place along the dilution line being investigated by a set of complementary techniques. With high AP degradation observed after 56 days, two stabilization approaches, i.e., the addition of vitamin C or increasing AP concentration, were proposed. As a rule, LC samples with the lowest water content resulted in better AP stability (up to 52% of nondegraded AP in LC1 after 28 days) and faster API release (~18% in 8 h) as compared to the most diluted sample (29% of nondegraded AP in LC8 after 28 days, and up to 12% of AP released in 8 h). In addition, LCs exhibited a skin barrier-strengthening effect with up to 1.2-fold lower transepidermal water loss (TEWL) and 1.9-fold higher skin hydration observed in vitro on the porcine skin model. Although the latter cannot be linked to LCs' composition or specific microstructure, the obtained insight into LCs' microstructure contributed greatly to our understanding of AP positioning inside the system and its release profile, also influencing the overall LCs' performance after dermal application.

Phenylobacterium montanum sp. nov., an oligotrophic, slightly acidophilic mesophile isolated from sandy soil.

A bacterial strain, designated S6T, was isolated from the sandy soil on a rocky mountain in South China. Cells of S6T were Gram-stain-negative, aerobic, non-spore-forming, non-motile and non-prosthecae-producing. 16S rRNA gene sequence analysis revealed the highest similarities to 12 uncultured bacteria, followed by Phenylobacterium sp. B6.10-61 (97.14 %). The closest related validly published strains are Caulobacter henricii ATCC 15253T (96.15 %), Phenylobacterium conjunctum FWC 21T (96.08 %) and Caulobacter mirabilis FWC 38T (96.08 %). Phylogenetic analysis based on 16S rRNA gene, genome and proteome sequences demonstrated that S6T formed a separated lineage in the genus Phenylobacterium. Strain S6T contained Q-10 (97.5 %) as the major ubiquinone and C18 : 1 ω7c and C16 : 0 as the major fatty acids. The polar lipid profile consisted of phosphatidylglycerol, an unknown phosphoglycolipid and three unknown glycolipids. The assembled genome comprises a chromosome with a length of 5.5 Mb and a plasmid of 96 014 bp. The G+C content was 67.6 mol%. The morphological, physiological, chemotaxonomic and phylogenetic analyses clearly distinguished this strain from its closest phylogenetic neighbours. Thus it is proposed that strain S6T represents a novel species in the genus Phenylobacterium, for which the name Phenylobacterium montanum sp. nov. is proposed. The type strain is S6T (=NBRC 115419T=GCMCC 1.18594T).

Chemical Composition and Lipid Bioactive Components of Centaurea thracica Dwelling in Bulgaria.

Centaurea thracica (Janka) Hayek is a plant common in southern Bulgaria. The inflorescences were collected during June and September 2021, while their seeds were obtained in September 2021. The chemical and lipid composition of the inflorescences during the vegetation process of the plant were established. A significant decrease in total proteins (from 8.7 to 7.4%), glyceride oils (2.0-1.7%), and ash (4.5-4.2%) content was observed, while the amount of carbohydrates (72.3-77.2%) and fibers (28.7-35.8%) increased. During the vegetation of the plant, the content of oleic and linoleic acids increased up to 2-3 times, while the level of palmitic acid decreased. The lipids from the seeds were rich in oleic (53.0%) and palmitic (36.2%) acids. The tocopherol content in the oils of the inflorescences during vegetation increased from 58 to 110 mg/kg, and the content in the oil from the seeds was 260 mg/kg. The phospholipid content decreased during vegetation, and differences were observed in the composition between the inflorescences and the seeds. The high content of oleic acid, linoleic acid, tocopherols, and phospholipids determine the nutritional and biological value of the oils isolated from Centaurea thracica, and contribute to their potential use in various directions.

Combined UPLC-QqQ-MS/MS and AP-MALDI Mass Spectrometry Imaging Method for Phospholipidomics in Obese Mouse Kidneys: Alleviation by Feeding Sea Cucumber Phospholipids.

Sea cucumber phospholipids have ameliorative effects on various diseases related to lipid metabolism. However, it is unclear whether it can ameliorate obesity-associated glomerulopathy (ORG) induced by a high-fat diet (HFD). The present study applied UPLC-QqQ-MS/MS and atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry imaging (AP-MALDI MSI) to investigate the effects of sea cucumber phospholipids, including plasmalogen PlsEtn and plasmanylcholine PakCho, on phospholipid profiles in the HFD-induced ORG mouse kidney. Quantitative analysis of 135 phospholipids revealed that PlsEtn and PakCho significantly modulated phospholipid levels. Notably, PlsEtn modulated kidney overall phospholipids better than PakCho. Imaging the "space-content" of 9 phospholipids indicated that HFD significantly increased phospholipid content within the renal cortex. Furthermore, PlsEtn and PakCho significantly decreased the expression of transport-related proteins CD36, while elevating the expression of fatty acid ß-oxidation-related protein PPAR-α in the renal cortex. In conclusion, sea cucumber phospholipids reduced renal lipid accumulation, ameliorated renal damage, effectively regulated the content and distribution of renal phospholipids, and improved phospholipid homeostasis, exerting an anti-OGR effect.

Phospholipid-induced secondary structural changes of lysozyme polymorphic amyloid fibrils studied using vacuum-ultraviolet circular dichroism.

The hallmark of amyloidosis, such as Alzheimer's disease and Parkinson's disease, is the deposition of amyloid fibrils in various internal organs. The onset of the disease is related to the strength of cytotoxicity caused by toxic amyloid species. Furthermore, amyloid fibrils show polymorphism, where some types of fibrils are cytotoxic while others are not. It is thus essential to understand the molecular mechanism of cytotoxicity, part of which is caused by the interaction between amyloid polymorphic fibrils and cell membranes. Here, using amyloid polymorphs of hen egg white lysozyme, which is associated with hereditary systemic amyloidosis, showing different levels of cytotoxicity and liposomes of DMPC and DMPG, changes in the secondary structure of the polymorphs and the structural state of phospholipid membranes caused by the interaction were investigated using vacuum-ultraviolet circular dichroism (VUVCD) and Laurdan fluorescence measurements, respectively. Analysis has shown that the more cytotoxic polymorph increases the antiparallel ß-sheet content and causes more disorder in the membrane structure while the other less cytotoxic polymorph shows the opposite structural changes and causes less structural disorder in the membrane. These results suggest a close correlation between the structural properties of amyloid fibrils and the degree of structural disorder of phospholipid membranes, both of which are involved in the fundamental process leading to amyloid cytotoxicity.

Dietary liposomal complexes change the fatty acid composition of hepatic bioactive phospholipids in F1(C57blxDBA2\6) mice, as shown by a lipidomic approach.

Essential polyunsaturated fatty acids (PUFAs) of the n-3 and n-6 classes are crucial for maintaining many physiological functions of the human body. It has previously been suggested that the beneficial effects of n-3 PUFAs are mediated by the action of bioactive lipid components, although it remains unclear which specific lipids are metabolically active. The aim of this study was to assess the impact of various liposomal diets on the content and ratio of liver phospholipids, containing n-3 and n-6 PUFAs, in F1 (C57blxDBA2\6) mice. Lipidomic analysis using chromatography-mass spectrometry was employed to investigate changes in the fatty acid profile of liver phospholipids in six groups of mice. These mice were fed liposomal complexes of different compositions in drinks replacing water for a long-term diet (3 months). Two additional groups of mice, aged 2 and 5 months, were used as control groups. The six liposomal complexes included different combinations of phosphatidylcholine (PC), a natural antioxidant (clove bud essential oil (CEO)), fish oil (FO), and sodium caseinate (SC). The consumption of the PC-CEO-FO-SC liposomal complex significantly increased the amount of liver phospholipids containing n-3 docosahexaenoic acid, including phosphatidylcholines, phosphatidylethanolamines (PE), phosphatidylserines (PS), and lysophosphatidylcholine (LPC). This increase was accompanied by a marked decrease in the amount of phospholipids containing n-6 arachidonic acid. As a result, the weight ratio of phospholipids containing n-6 PUFAs to those containing n-3 PUFAs decreased significantly, especially for PC and PE subclasses. Therefore, the PC-CEO-FO-SC liposomal complex has the potential to enhance resistance to inflammation and reduce the risk of non-communicable diseases.

A change in metal cation switches selectivity of a phospholipid sensor from phosphatidic acid to phosphatidylserine.

Phosphatidic acid and phosphatidylserine are anionic phospholipids with emerging signalling roles in cells. Determination of how phosphatidic acid and phosphatidylserine change location and quantity in cells over time requires selective fluorescent sensors that can distinguish these two anionic phospholipids. However, the design of such synthetic sensors that can selectively bind and respond to a single phospholipid within the complex membrane milieu remains challenging. In this work, we present a simple and robust strategy to control the selectivity of synthetic sensors for phosphatidic acid and phosphatidylserine. By changing the coordination metal of a dipicolylamine (DPA) ligand from Zn(II) to Ni(II) on the same synthetic sensor with a peptide backbone, we achieve a complete switch in selectivity from phosphatidic acid to phosphatidylserine in model lipid membranes. Furthermore, this strategy was largely unaffected by the choice and the position of the fluorophores. We envision that this strategy will provide a platform for the rational design of targeted synthetic phospholipid sensors to probe plasma and intracellular membranes.

Impact of Ionic Liquids on the Physicochemical Behavior of Vesicles.

The effects of two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and 1-butyl-1-methyl pyrrolidinium tetrafluoroborate ([bmp]BF4), on a mixture of phospholipids (PLs) 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) (6:3:1, M/M/M, 70% PL) in combination with 30 mol % cholesterol (CHOL) were investigated in the form of a solvent-spread monolayer and bilayer (vesicle). Surface pressure (π)-area (A) isotherm studies, using a Langmuir surface balance, revealed the formation of an expanded monolayer, while the cationic moiety of the IL molecules could electrostatically and hydrophobically bind to the PLs on the palisade layer. Turbidity, dynamic light scattering (size, ζ-potential, and polydispersity index), electron microscopy, small-angle X-ray/neutron scattering, fluorescence spectroscopy, and differential scanning calorimetric studies were carried out to evaluate the effects of IL on the structural organization of bilayer in the vesicles. The ILs could induce vesicle aggregation by acting as a "glue" at lower concentrations (<1.5 mM), while at higher concentrations, the ILs disrupt the bilayer structure. Besides, ILs could result in the thinning of the bilayer, evidenced from the scattering studies. Steady-state fluorescence anisotropy and lifetime studies suggest asymmetric insertion of ILs into the lipid bilayer. MTT assay using human blood lymphocytes indicates the safe application of vesicles in the presence of ILs, with a minimal toxicity of up to 2.5 mM IL in the dispersion. These results are proposed to have applications in the field of drug delivery systems with benign environmental impact.

Stability Enhancement by Hydrophobic Anchoring and a Cross-Linked Structure of a Phospholipid Copolymer Film for Medical Devices.

Surface modification using zwitterionic 2-methacryloyloxyethylphosphorylcholine (MPC) polymers is one of the most reasonable ways to prepare medical devices that can suppress undesired biological reactions such as blood coagulation. Usable MPC polymers are hydrophilic and water soluble, and their surface modification strategy involves exploiting the copolymer structures by adding physical or chemical bonding moieties. In this study, we developed copolymers composed of MPC, hydrophobic anchoring moiety, and chemical cross-linking unit to clarify the role of hydrophobic interactions in achieving biocompatible and long-term stable coatings. The four kinds of MPC copolymers with cross-linking units, such as 3-methacryloxypropyl trimethoxysilane (MPTMSi), and four different hydrophobic anchoring moieties, such as 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane (MPTSSi) named as PMMMSi, n-butyl methacrylate (BMA) as PMBSi, 2-ethylhexyl methacrylate (EHMA) as PMESi, and lauryl methacrylate as PMLSi, were synthesized and coated on polydimethylsiloxane, polypropylene (PP), and polymethyl pentene. These copolymers were uniformly coated on the substrate materials PP and poly(methyl pentene) (PMP), to achieve hydrophilic and electrically neutral coatings. The results of the antibiofouling test showed that PMBSi repelled the adsorption of fluorescence-labeled bovine serum albumin the most, whereas PMLSi repelled it the least. Notably, all four copolymers suppressed platelet adhesion similarly. The variations in protein adsorption quantities among the four copolymer coatings were attributed to their distinct swelling behaviors in aqueous environments. Further investigations, including 3D scanning force microscopy and neutron reflectivity measurements, revealed that the PMLSi coating exhibited a higher water intake under aqueous conditions in comparison to the other coatings. Consequently, all copolymer coatings effectively prevented the invasion of platelets but the proteins penetrated the PMLSi network. Subsequently, the dynamic stability required to induce shear stress was evaluated using a circulation system. The results demonstrated that the PMMMSi and PMLSi coatings on PMP and PP exhibited exceptional platelet repellency and maintained high stability during circulation. This study highlights the potential of hydrophobic moieties to improve hemocompatibility and stability, offering potential applications in medical devices.

Biophysical impact of lubricating base oil aerosols on natural pulmonary surfactant film.

Lubricating base oils have been extensively employed for producing various industrial and consumer products. Therefore, their environmental and health impacts should be carefully evaluated. Although there have been many reports on pulmonary cytotoxicity and inflammatory responses of inhaled lubricating base oils, their potential influences on pulmonary surfactant (PS) films that play an essential role in maintaining respiratory mechanics and pulmonary immunity remains largely unknown. Here a systematic study on the interactions between an animal-derived natural PS and aerosols of water and representative mineral and vegetable base oils is performed using a novel biophysical assessing technique called constrained drop surfactometry capable of providing in vitro simulations of normal tidal breathing and physiologically relevant temperature and humidity in the lung. It was found that the mineral oil aerosols can impose strong inhibitions to the biophysical property of PS film, while the airborne vegetable oils and water show negligible adverse effects within the studied concentration range. The inhibitory effect is originated from the strong hydrophobicity of mineral oil, which makes it able to disrupt the interfacial molecular ordering of both phospholipid and protein compositions and consequently suppress the formation of condensed phase and multilayer scaffolds in a PS film. ENVIRONMENTAL IMPLICATION: Understanding the biophysical influence of airborne lubricating base oils on pulmonary surfactant (PS) films can provide new insights into the environmental impacts and health concerns of various industrial lubricant products. Here a comparative study on interactions between an animal-derived natural PS film and the aerosols of water and representative mineral and vegetable base oils under the true physiological conditions was conducted in situ using constrained drop surfactometry. We show that the most frequently used mineral base oil can cause strong inhibitions to the PS film by disrupting the molecular ordering of saturated phospholipids and surfactant-associated proteins at the interface.

Effect of cholesterol on nanoparticle translocation across a lipid bilayer.

Nanoparticles (NPs) have attracted significant attention as carriers for the delivery of drugs, genes, and macromolecules for biomedical and therapeutic applications. These technologies require NPs to be delivered to the interior of the cell. However, this translocation is unlikely because of the presence of a cell membrane composed of phospholipids, cholesterol, proteins, and glycans. The cell membrane composition can influence its rigidity; thus, membrane composition is a crucial factor in determining the translocation of NPs across the cell membrane. Here, we focus on cholesterol, which is an essential component of biological cell membranes, and investigate NP translocation across membranes containing cholesterol under an applied electric field using a coarse-grained molecular dynamics simulation. We found that NPs could translocate directly across cholesterol-containing membranes without irreversible membrane disruption. This unique translocation was induced by two key phenomena. Before NP translocation, a phospholipid-rich/cholesterol-poor domain was formed at the NP-membrane contact interface. Second, a smaller transmembrane pore was formed in the cholesterol-containing membrane during membrane crossing of the NP. Our findings imply that the delivery of NPs to the cell interior across the cholesterol-containing membrane can be achieved by appropriately controlling the strength of the applied electric field, depending on the cholesterol content in the membrane.

Mechanism of Cationic Lipid Induced DNA Condensation: Lipid-DNA Coordination and Divalent Cation Charge Fluctuations.

The condensation of nucleic acids by lipids is a widespread phenomenon in biology with crucial implications for drug delivery. However, the mechanisms of DNA assembly in lipid bilayers remain insufficiently understood due to challenges in measuring and assessing each component's contribution in the lipid-DNA-cation system. This study uses all-atom molecular dynamics simulations to investigate DNA condensation in cationic lipid bilayers. Our exhaustive exploration of the thermodynamic factors reveals unique roles for phospholipid head groups and cations. We observed that bridging cations between lipid and DNA drastically reduce charges, while mobile magnesium cations "ping-ponging" between double strands create charge fluctuations. While the first factor stabilizes the DNA-lipid complex, the latter creates attractive forces to induce the spontaneous condensation of DNAs. This novel mechanism not only sheds light on the current data regarding cationic lipid-induced DNA condensation but also provides potential design strategies for creating efficient gene delivery vectors for drug delivery.

Imaging Interorganelle Phospholipid Transport by Extended Synaptotagmins Using Bioorthogonally Tagged Lipids.

The proper distribution of lipids within organelle membranes requires rapid interorganelle lipid transport, much of which occurs at membrane contact sites and is mediated by lipid transfer proteins (LTPs). Our current understanding of LTP mechanism and function is based largely on structural studies and in vitro reconstitution. Existing cellular assays for LTP function use indirect readouts, and it remains an open question as to whether substrate specificity and transport kinetics established in vitro are similar in cellular settings. Here, we harness bioorthogonal chemistry to develop tools for direct visualization of interorganelle transport of phospholipids between the plasma membrane (PM) and the endoplasmic reticulum (ER). Unnatural fluorescent phospholipid analogs generated by the transphosphatidylation activity of phospholipase D (PLD) at the PM are rapidly transported to the ER dependent in part upon extended synaptotagmins (E-Syts), a family of LTPs at ER-PM contact sites. Ectopic expression of an artificial E-Syt-based tether at ER-mitochondria contact sites results in fluorescent phospholipid accumulation in mitochondria. Finally, in vitro reconstitution assays demonstrate that the fluorescent lipids are bona fide E-Syt substrates. Thus, fluorescent lipids generated in situ via PLD activity and bioorthogonal chemical tagging can enable direct visualization of the activity of LTPs that mediate bulk phospholipid transport at ER-PM contact sites.

Salinibacterium soli sp. nov., isolated from lakeside soil.

A Gram-stain-positive, rod-shaped, non-spore-forming and non-motile bacterium, designated strain WY-16T. Growth was observed at 20-42 °C (optimum, 30 °C), pH 6-9 (optimum, pH 7) and salinity of 0-3 % (w/v; optimum, 1 %). Phylogenetic analysis based on genome sequences indicated that WY-16T was affiliated to the family Microbacteriaceae and most closely related to Salinibacterium xinjiangense and Salinibacterium amurskyense. The average nucleotide identity values between strain WY-16T and S. xinjiangense and S. amurskyense were 74.7 and 72.5 %, respectively. The digital DNA-DNA hybridization values between strain WY-16T and S. xinjiangense and S. amurskyense were 19.6 and 18.6 %, respectively. The predominant fatty acids were anteiso-C15 : 0, iso-C16 : 0 and iso-C16 : 0 10-methyl. The major menaquinones were MK-12, MK-13, MK-14 and MK-15. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified glycolipid and one unidentified phospholipid. The cell-wall peptidoglycan contained 2,4-diaminobutyric acid as the diamino acid and ribose, rhamnose, glucose and galactose were the major cell-wall sugars. Based on phenotypic, genotypic and phylogenetic evidence, strain WY-16T represents a novel species in the genus Salinibacterium, for which the name Salinibacterium soli sp. nov. is proposed. The type strain is WY-16T (=GDMCC 1.4011T=JCM 36421T).