Nonpolar Lipids Research Articles

Shake It Off! Acoustic Manipulation of Lipid Vesicles for Mass Spectrometric Analysis.

Analyzing lipid assemblies, including liposomes and extracellular vesicles (EVs), is challenging due to their size, diverse composition, and tendency to aggregate. Such vesicles form with a simple phospholipid bilayer membrane, and they play important roles in drug discovery and delivery. The use of mass spectrometry (MS) allows for broad analysis of lipids from different classes; however, their release from the higher order structural aggregates is typically achieved by chemical means. Mechanical disruption by high frequency surface acoustic waves (SAW) is presented as an appealing alternative to preparing lipid vesicles for MS sampling. In this work, SAWs used to disrupt liposomes allow for the direct analysis of their constituent lipids by employing SAW nebulization with corona discharge (CD) ionization. We explore the effects of duration, frequency, and incorporation of nonpolar lipids, including cholesterol, on the SAW's ability to disrupt the liposome. We also report on the successful MS analysis of liposome-derived lipids along with cytochrome C in solution, thus demonstrating applications to aqueous samples and native MS conditions.

Aziridination-Assisted Mass Spectrometry of Nonpolar Sterol Lipids with Isomeric Resolution.

Characterization of nonpolar lipids is crucial due to their essential biological functions and ability to exist in various isomeric forms. In this study, we introduce the N-H aziridination method to target carbon-carbon double bonds (C═C bonds) in nonpolar sterol lipids. The resulting fragments are readily dissociated upon collision-induced dissociation, generating specific fragment ions for C═C bond position determination and fingerprint fragments for backbone characterization. This method significantly enhances lipid ionization efficiency, thereby improving the sensitivity and accuracy of nonpolar lipid analysis. We demonstrated that aziridination of sterols leads to distinctive fragmentation pathways for chain and ring C═C bonds, enabling the identification of sterol isomers such as desmosterol and 7-dehydrocholesterol. Furthermore, aziridination can assist in identifying the sterol backbone by providing fingerprint tandem mass spectra. We also demonstrated the quantitative capacity of this approach with a limit of detection of 10 nM in the solvent mixture of methanol and water. To test the feasibility of this method in complex biological samples, we used mouse prostate cancerous tissues and found significant differences in nonpolar lipid profiles between healthy and cancerous samples. The high efficiency and specificity of aziridination-assisted mass spectrometric analysis, as well as its quantitative analysis ability, make it highly suitable for broad applications in nonpolar lipid research.

The role of quantum-chemical descriptors and sigma-profile overlapping of different co-solvents on tuning ethanolic extraction of soybean oil

Co-solvents can significantly improve ethanol efficiency in vegetable oil extraction, making their use a viable, cost-effective, and sustainable alternative to conventional solvents. The challenge, however, is to understand the complex interactions between the solvents and how this can affect the yield and quality of the extracted oil. In this study, the COnductor-like Screening Model with Segment Activity Coefficient and Hansen solubility parameters were combined and used to optimize soybean oil extraction using ethanol along with seven different co-solvents. In parallel, an experimental approach was carried out to verify the accuracy of the models. Both theoretical and empirical results indicated that the oil extraction yield decreased as the co-solvent polarity increased. The best performance in solubilizing non-polar lipids was observed for the mixture of 10 wt% of p-cymene, a non-polar solvent, with 90 wt% ethanol, reaching a yield of 24.35 g/100 g. According to the thermodynamic analysis, the effects of polarity weigh heavily on the standard entropy, which rules the driving force of mass transfer during the extraction. The interaction mechanisms were carefully investigated employing quantum mechanical calculations, revealing how the differences in chemical potential (μ), hardness (η), and electrophilicity (ω) underlie the macroscopic results and rule the efficiency obtained for different solvent ratios and combinations.

Proteomics coupled transcriptomics reveals lipopolysaccharide inhibiting peroxisome proliferator-activated receptors signalling pathway to reduce lipid droplets accumulation in mouse liver.

Lipid droplets (LDs) are multifunctional organelles consisting of a central compartment of non-polar lipids shielded from the cytoplasm by a phospholipid monolayer. The excessive accumulation of LDs in cells is closely related to the development and progression of many diseases in humans and animals, such as liver-related and cardiovascular diseases. Thus, regulating the LDs size and abundance is necessary to maintain metabolic homeostasis. This study found that lipopolysaccharide (LPS) stimulation reduced the LDs content in the mouse liver. We tried to explain the possible molecular mechanisms at the broad protein and mRNA levels, finding that inhibition of the peroxisome proliferator-activated receptors (PPAR) signalling pathway by LPS may be a critical factor in reducing LDs content.

Lipid availability during in vitro maturation alters oocyte lipid content and blastocyst development and metabolism.

Lipids play a crucial role in various biological functions, including membrane composition, energy storage, cell signalling, and metabolic and epigenetic processes. Abnormal lipid accumulation and metabolism during in vitro maturation (IVM) of oocytes have been linked to the use of fetal bovine serum (FBS), even though it provides several beneficial molecules, contributing to the oocyte competence. Delipidating agents have been used to mitigate these deleterious effects, but they can have adverse effects on embryonic development. In this study, we explored how lipids present in fetal bovine serum (FBS) can impact the composition of oocytes and their resulting blastocysts in vitro. For that, we used organic solvents to separate the polar and nonpolar (lipid enriched) phase of FBS. Oocytes were in vitro matured in the presence of 10% whole FBS (control), 10% FBS plus 10% nonpolar lipids (lipid enriched - OL) or 10% polar lipids only (partially delipidated - ODL). After 24 h, part of the matured oocytes was collected and those remaining in each group underwent in vitro fertilization (IVF) and culture (IVC) under the same conditions and expanded blastocysts were collected at day 7 (control, BL and BDL). Oocytes and embryos were analysed by Multiple Reaction Monitoring mass spectrometry (MRM-MS) to determine their lipid composition. Interestingly, principal component analysis (PCA) revealed a clear distinction in the lipid profile of oocytes and blastocysts from both treatments compared to the control group. Control oocytes and blastocysts had higher triacylglycerol and cholesterol ester enrichment while the OL, ODL, BL and BDL groups had higher amounts of free fatty acids (FFAs). The structural and signalling phospholipids also differed among groups. Our findings suggest that the lipid-enriched fraction of FBS can be manipulated for IVM to ensure proper maturation, resulting in oocytes and blastocysts with less accumulated intracellular lipids and an improved metabolic status.

ZFP750 affects the cutaneous barrier through regulating lipid metabolism.

An essential function of the epidermis is to provide a physical barrier that prevents the loss of water. Essential mediators of this barrier function include ceramides, cholesterol, and very long chain fatty acids, and their alteration causes human pathologies, including psoriasis and atopic dermatitis. A frameshift mutation in the human ZNF750 gene, which encodes a zinc finger transcription factor, has been shown to cause a seborrhea-like dermatitis. Here, we show that genetic deletion of the mouse homolog ZFP750 results in loss of epidermal barrier function, which is associated with a substantial reduction of ceramides, nonpolar lipids. The alteration of epidermal lipid homeostasis is directly linked to the transcriptional activity of ZFP750. ZFP750 directly and/or indirectly regulates the expression of crucial enzymes primarily involved in the biosynthesis of ceramides. Overall, our study identifies the transcription factor ZFP750 as a master regulator epidermal homeostasis through lipid biosynthesis and thus contributing to our understanding of the pathogenesis of several human skin diseases.

Phospholipids molecular species, proteins secondary structure, and emulsion microstructure of egg yolk with reduced polar and/or nonpolar lipids

This study investigated the phospholipids (PLs) molecular species (PLs-MS), protein secondary structure (PSS), and emulsion microstructure of the egg yolk (EY) treated with supercritical-CO2 (T1), hexane (T2), and ethanol {at room temperature (T3) and 65 °C (T4)}. PLs-MS, PSS, and microstructure of EY emulsion were investigated with UPLC-Q-TOF-MS, Fourier-transforms infrared and Raman spectroscopy, and confocal laser scanning microscope, respectively. Predominant PLs molecular fractions were C18:0-C20:4, C18:0-C20:4, C16:0-C18:2, C16:0, C18:0-C18:2, and d18:1/16:0, for phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, lysophosphatidylcholine, sphingomyelin, and phosphatidylserine, respectively. All the PLs-MS were highest for T1 and many of them (C14:0-C16:0, C18:0-C18:1, C18:0-C20:3) were absent in T2, T3, and T4. PSS components (α–helices, β–sheets, β-turn, and random coil) were highest for T4, followed by T3, T2, T1, and control (non-treated EY). However, T1-added o/w emulsion showed excellent stability (95.64 %) with smaller and denser oil droplets due to better ionic interactions by synergistic effect of PLs-MS and PSS components.

Novel insights into the structure and function of dengue virus NS1 protein.

The dengue flavivirus is responsible for dengue fever. While generally mild, a proportion of cases develop into life-threatening dengue haemorrhagic fever. Flaviviruses produce a non-structural protein, NS1, that is essential to flavivirus genome replication, though it has no known catalytic function. Early in infection, dimeric NS1 localises on the endoplasmic reticulum membrane at the site of viral RNA replication and may be involved in the replication complexs formation. Later on NS1 is secreted as a hexameric lipoprotein that interacts with components of the complement-mediated immune system. In 2014, crystal structures of full-length, glycosylated, and truncated West Nile Virus and Dengue Type 2 Virus (DENV2) NS1 dimers were obtained, which have aided interpretation of low-resolution cryo-electron microscopy reconstructions of the hexameric structure of secreted NS1. This along with biochemical and NMR analyses of the NS1 lipid cargo was used to build and simulate models of the DENV2 NS1 hexamer with and without a lipid cargo. Coarse-grained molecular dynamics simulations showed that the glycosylation of NS1 is essential for hexamer stability, with the glycans compensating for the paucity of protein-protein contacts between dimers. Lipid loaded NS1 hexamers can pick up lipids from their environment and deposit lipids into membranes but are not able to pick up lipids from membranes, whereas NS1 hexamers without a lipid cargo are not effective at picking up environmental lipids. The lipid cargo forms a dumbbell shape, with polar lipids towards the outside of the bulbs and non-polar lipids in the centre of the bulbs and bar of the dumbbell. These results add to our somewhat scarce understanding of the otherwise enigmatic function of a protein whose presence is an important biomarker for dengue fever, but whose role in infection has been controversial and not well understood.

A combined experimental-computational approach to study interactions of topical ophthalmologic drugs with a tear film model.

Many topical ophthalmologic drug formulations are based on micellar drug delivery. Recently, a state-of-the-art delivery approach was suggested utilizing complex oil-in-water nanoemulsions loaded with active drug molecules. We study drug nanocarriers consisting of nanodroplets of nonpolar lipids with varying chain lengths coated with cationic surfactants. We employ both experimental and computational approaches. In experiments, we use a unique in vitro system that models human tear film. It mimics eye-blinking with tear inflow and evaporation. The device also allows control of the blinking rate and uses fluorescein staining to visualize the tear film model upon administration of topical ophthalmologic drugs. In the computational approach,

Effect of Model Tear Film Lipid Layer on Water Evaporation.

A majority of in vitro models were incapable of reproducing the evaporation resistance of tear film lipid layer (TFLL) in vivo. The purpose of this research is to develop a novel in vitro model to study the effect of TFLL on water evaporation. A ventilated, closed-chamber, droplet evaporimeter with a constant surface area has been invented to study the evaporation resistance of TFLL. This evaporimeter ensures a rigorous control of environmental conditions, including the temperature, relative humidity, airflow rate, surface area, and surface pressure, thus allowing for reproducible water evaporation measurements over a time period of only 5 minutes. The volumetric evaporation rate of this droplet evaporimeter is less than 2.7 µL/min, comparable to the basal tear production of healthy adults. Together with direct film imaging using atomic force microscopy (AFM), we have studied the effect of a model TFLL on water evaporation, as a function of the lipid composition and surface pressure. A model TFLL composed of 40% wax esters, 40% cholesteryl esters, and 20% polar lipids was capable of reducing the water evaporation rate by 11% at surface pressure 47 mN/m. AFM revealed that the model TFLL at high surface pressures consists of discrete droplets/aggregates of the nonpolar lipids residing atop a polar lipid monolayer with phase separation. The TFLL may resist water evaporation with a combined mechanism by increasing film compactness of the polar lipid film at the air-water surface, and, to a lesser extent, by increasing film thickness of the nonpolar lipid film.

Expression of glycerol-3-phosphate acyltransferase increases non-polar lipid accumulation in Nannochloropsis oceanica

Microalgae are considered a suitable production platform for high-value lipids and oleochemicals. Several species including Nannochloropsis oceanica produce large amounts of essential omega-3 polyunsaturated fatty acids (PUFAs) which are integral components of food and feed and have been associated with health-promoting effects. N. oceanica can further accumulate high contents of non-polar lipids with chemical properties that render them a potential replacement for plant oils such as palm oil. However, biomass and lipid productivities obtained with microalgae need to be improved to reach commercial feasibility. Genetic engineering can improve biomass and lipid productivities, for instance by increasing carbon flux to lipids. Here, we report the overexpression of glycerol-3-phosphate acyltransferase (GPAT) in N. oceanica during favorable growth conditions as a strategy to increase non-polar lipid content. Transformants overproducing either an endogenous (NoGPAT) or a heterologous (Acutodesmus obliquus GPAT) GPAT enzyme targeted to the endoplasmic reticulum had up to 42% and 51% increased non-polar lipid contents, respectively, compared to the wild type. Biomass productivities of transformant strains were not substantially impaired, resulting in lipid productivities that were increased by up to 37% and 42% for NoGPAT and AoGPAT transformants, respectively. When exposed to nutrient stress, transformants and wild type had similar lipid contents, suggesting that GPAT enzyme exerts strong flux control on lipid synthesis in N. oceanica under favorable growth conditions. NoGPAT transformants further accumulated PUFAs in non-polar lipids, reaching a total of 6.8% PUFAs per biomass, an increase of 24% relative to the wild type. Overall, our results indicate that GPAT is an interesting target for engineering of lipid metabolism in microalgae, in order to improve non-polar lipid and PUFAs accumulation in microalgae.

Nonpolar Lipids Contribute to Midday Fogging During Scleral Lens Wear.

To determine correlations between lipids in the fluid reservoir (FR) and the severity of midday fogging (MDF) in scleral lens (SL) wear. SL neophytes were recruited to wear custom SL for 4 days, examined after 8 hours on days 1 and 4. Lens vault and MDF were quantified from anterior segment optical coherence tomography (AS-OCT), and the FR was collected and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Relative abundance of lipids was compared to MDF scores using nonparametric correlation testing (Spearman rank). Ocular surface and SL fitting characteristics (lens vault, fitting curves) were likewise compared to MDF. Thirteen participants (26 eyes, 69% female, 28 ± 9 years old) were included in this study. MDF severity after 8 hours of SL wear was 33 ± 29 units on day 1 and 28 ± 24 units on day 4 (r=.94; P < 0.01). Twelve samples were analyzed using LC-MS/MS, and a total of 170 distinct lipid species were detected. The lipid classes with greatest correlation to MDF were the wax esters (r=.73, P=0.01), cholesteryl esters (r=.59; P=0.049), and triacylglycerols (r=.64, P=0.03). Polar lipids were observed abundantly in all samples. None of the measured ocular surface or fitting outcomes were correlated to MDF. Nonpolar lipids were the greatest contributors to MDF among these normal participants. Polar lipids may be due to cellular debris, although they do not appear contributory to MDF.

Temporal and intra-thallus variation in arsenic species in the brown macroalga Laminaria digitata

Environmental context Arsenic contamination has a disproportionate effect on marine ecosystems. Organisms such as some marine macroalgae, which accumulate potentially toxic elements from the surrounding environment, have developed an internal conversion process that is not yet fully understood. Are arsenic-containing sugars a product of detoxification, or simply the result of phospholipid degradation?Rationale Arsenosugars (AsSugar) account for the majority of total arsenic in common seaweed species, yet it is unclear whether these are formed through some detoxification pathway for inorganic arsenic or are precursors/degradation products of arsenic-containing phospholipids in the cell wall.Methodology Temporal and intra-thallus variations in water-soluble arsenic were measured by HPLC-ICP-MS, as well as total non-polar and polar arsenic-containing lipids by ICP-MS in Laminaria digitata to offer potential insight into the origins of arsenosugars. Water-soluble speciation with and without freeze-drying were also compared to determine whether freeze-drying changes the water-soluble As speciation.Results In general, lower levels of total As were detected in the samples collected in May (39.2–74.5 mg kg−1) compared to those collected in February (72.6–151 mg kg−1). The concentration of arsenate was found to consistently increase along the thallus from the holdfast/stipe (0.78–1.82 mg kg−1) to the decaying fronds (44.4–61.0 mg kg−1) in both months, and AsSug-SO3 was the dominant AsSugar in the majority of samples. The extraction efficiency was lower in fresh samples (64–77%) than in freeze-dried (95–116%) from the same month. Water-soluble, polar AsLipids, and residual As concentrations, were generally highest in February, and the non-polar AsLipids accounted for <0.42% of totAs in all samples.Discussion Our results suggest that the arsenosugars are not a product of arsenic detoxification, but a by-product of normal biological activity. It is probable that the arsenosugars are bound to the cell membrane within the Laminaria digitata cells, and lyophilisation is required to release them quantitatively. Future research should focus on speciation of polar lipid-soluble As extracted from fresh samples to determine if the lower extraction efficiency observed in this study is due to the As being in an unextractable form, i.e. lipids, and thus is not removed from cells during water-based extractions.

Evaluation of genotype-environment interactions for non-polar lipids and fatty acids in chickpea (Cicer arietinum L.) seeds

Genotype-environment (G × E) interactions for non-polar lipids and fatty acids were studied in 28 chickpea accessions. The total nonpolar lipid content was determined by Soxhlet procedure; fatty acid profiles were investigated by gas chromatography. There were strong negative correlations between oleic and linoleic acids and between oleic and linolenic acids. The correlation between linoleic and linolenic acids was positive and either strong or moderate. Correlations between the other acids were differently directed and of various strengths. Line Luh 99/11 turned out to be an outlier in relation to the other genotypes due to an unusually high content of stearic acid. Cultivar CDC Jade was an outlier because of too low content of stearic acid and too high content of linoleic acid. Accession UD0502195 was an outlier due to a higher content of palmitic acid. Accessions UD0500022 and UD0502195 were outliers due to the low content of total nonpolar lipids. The variability in the total nonpolar lipid content was not affected by the environment, but the environment contributions to the variability of oleic and linoleic acids were very high. There were only statistically significant differences in the oleic and linoleic acid amounts between the cultivation years. There was a positive correlation between the oleic acid content and the average air temperature during the “anthesis – maturity” period and a negative correlation between the linoleic acid content and the average temperature during this period. There was also a negative correlation between the oleic acid content and precipitation during the “anthesis – maturity” period and a positive correlation between the linoleic acid content and precipitation during this period. The palmitic acid content was the most responsive to environmental changes in cultivar CDC Vanguard and the most resistant in cultivar Krasnokutskiy 123. The stearic acid content was the most sensitive to environmental changes in cultivar ILC 3279 and the most irresponsive in accession UKR001:0502116. As to oleic and linoleic acids, line L 273-18 had the bi (plasticity) and S2di (stability) values coupled with the corresponding mean contents, meaning that this genotype may be adapted to decreased temperature. The ecovalence values (Wi2) for the total nonpolar lipids, palmitic, stearic and linolenic acids indicated that these characteristics were little responsive to environmental fluctuations. As to oleic and linoleic acids, Wi2 values were much higher in many accessions, confirming the variability of these parameters depending on growing conditions. Having the highest Wi2 values, accession Garbanzo 2 is expected to show high degrees of the G × E interactions for oleic and linoleic acids. S2di was positively correlated with Wi2.

Process optimization and kinetics for ultrasonication assisted extraction of phospholipids from ghee residue

AbstractGhee is a major Indian dairy product with a pleasant flavor. During its manufacture, ghee residue is obtained as the by‐product, which consists of substantial quantity of phospholipids. Phospholipids exhibit emulsifying properties and offer some health benefits. The present study aimed to optimize the process parameters for the extraction of phospholipids from ghee residue (GR) using ultrasonication. The GR was subjected to a series of pre‐treatments before ultrasonication. The hot water treatment led to reduction in nonpolar lipids and improved polar lipids (35.47% fat basis). Taguchi orthogonal array design was employed for optimization of ultrasound power, treatment temperature, time and solvent:solid (S:S) ratio with phospholipid content and antioxidant activity as the response variables. The phospholipid content ranged between 18.54% and 23.89% and antioxidant activity of the extracted samples varied from 47.01% to 50.64% expressed as radical scavenging activity by DPPH assay, while for the untreated GR, the PL and antioxidant activity were 4.98% and 32.75%, respectively. The power level of 80%, 80°C treatment temperature, S:S ratio of 15 and sonication time of 4 min. resulted in maximum extraction of phospholipids (24.12%). The yield of phospholipids was quantified as 13.1% and 8.88% by two elution techniques using solid phase extraction methods. The predicted and experimental values for the responses were in good agreement with R2 value of 0.98. Power and temperature were found to be significant (p &lt; 0.01) in influencing phospholipids yield. For antioxidant activity of the extract, S:S ratio exerted significant effect (p &lt; 0.01). The experimental data were fit in four defined empirical models for understanding the extraction kinetics. Based on the R2 values, the models explained the kinetics in the following order: Parabolic model&gt;Power law&gt;Peleg's model&gt;Elovich's model.Practical applicationsPresently, ghee residue is often discarded as waste or used as animal feed by most of the ghee manufacturing dairy plants. Few studies were conducted to incorporate ghee residue as an ingredient in different food products. However, the present study opens new avenues for utilization of this by‐product for extraction of high value bioactive components, that is, phospholipids, with the help of novel technology; namely ultrasonication. The phospholipids have techno‐functional properties as an emulsifier. One of the classes of phospholipids, that is, sphingomyelin has unique health benefits, therefore this extract will also have scope as a nutraceutical. Thus, there is great practical utility for the present findings. In addition, for the scaling up of extraction techniques, the understanding of mass transfer kinetics is very vital and the same had been studied in the present investigation. Thus, the findings of this study are helpful in determining the ideal ultrasound‐assisted extraction conditions for extraction of phospholipids from ghee residue. Kinetics of extraction will help to explore opportunities for scale‐up of the process.

Exposure to polylactic acid induces oxidative stress and reduces the ceramide levels in larvae of greater wax moth (Galleria mellonella)

Plastic biodegradation by insects has made significant progress, opening up new avenues for the treatment of plastic waste. Wax moth larvae, for example, have attracted the attention of the scientific community because they are known to chew, ingest, and biodegrade natural polymer bee waxes. Despite this, we know very little about how these insects perform on manufactured plastics or how manufactured plastics affect insect metabolism. As a result, we studied the metabolism of greater wax moths (Galleria mellonella) fed on molasses-supplemented polylactic acid plastic (PLA) blocks. An analysis of the central carbon metabolism (CCM) metabolites was performed using liquid chromatography triple quadrupole mass spectrometry (LC-QQQ-MS), while an analysis of untargeted metabolites and lipids was conducted using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS). In total, 169 targeted CCM metabolites, 222 untargeted polar metabolites, and 196 untargeted nonpolar lipids were identified within the insect samples. In contrast, compared to control larvae, PLA-fed larvae displayed significantly different levels of 97 CCM metabolites, 75 polar metabolites, and 57 lipids. Purine and pyrimidine metabolisms were affected by PLA feeding, as well as amino acid metabolism, carbohydrates, cofactors, vitamins, and related metabolisms. Additionally, PLA exposure disrupted insect energy metabolism and oxidative stress, among other metabolic disturbances. The larvae fed PLA have lower levels of several lipids, suggesting a reduction in lipid reserves, and ceramide levels are likely to have changed due to apoptosis and inflammation. The study indicates that G. mellonella larvae could ingest PLA but this process causes some metabolic stress for the host. Future studies of the molecular pathways of this biodegradation process might help to provide strategies for stress reduction that would speed up insect digestion of plastic.

Langmuir Trough Study of the Interactions of Tear Mimetic Eyedrop Formulation with Human Meibum Films

Meibomian gland disease is associated with quantitative or qualitative deficiencies of meibum (MGS) that result in tear film instability. Thus, there is great demand for ophthalmic nanoemulsions that can replenish MGS and recover its performance at the air/tear surface. Rohto Dry Aid (RDA) utilizes TEARSHIELD TECHNOLOGYTM implementing a complex oil phase of non-polar and polar lipid-like molecules. Therefore, the interactions of RDA with MGS surface films deserve further study as they may provide valuable insights (i) into the mechanisms behind the nanoemulsion therapeutic action and (ii) for the design of novel ophthalmic formulations. Pseudobinary meibum/RDA films were formed at the air–water surface of the Langmuir trough. Surface pressure-area isocycles and stress relaxations were employed to probe the layer (i) reorganization upon cycling and (ii) dilatational elasticity, respectively. Film morphology was accessed by Brewster angle microscopy and the spreading properties of RDA-supplemented meibum were also probed. The diverse ingredients of the nanoemulsion oil phase complemented the non-polar and polar lipid constituents of the meibomian layers, which resulted in enhanced continuity of the MGS duplex film structure and facilitated the MGS spread and viscoelasticity. Nanoemulsions deserve further study as a potent tool for MGS-oriented therapy for dry eyes.

Characterization of polar and non-polar lipids of Hermetia illucens and Tenebrio molitor meals as animal feed ingredients

Although increasingly used in animal feeding, the black soldier fly (Hermetia illucens - HI) and mealworm (Tenebrio molitor - TM) larvae and pupae require the characterization and modulation of their fat profile for use in the feed industry. In this study, we provide a comprehensive fatty acid profile of the total lipid triglycerides and phospholipids, and sterol composition. For a more detailed characterization of the nutritional properties, we defined the profile of esterified fatty acids (FAs) in the sn-2 position of the triglycerides, which represents the most adsorbed fraction by animals during digestion. Twenty-four batches (12 batches per species divided into 6 batches of larvae and 6 batches of pupae) of 70 subjects were used for the analysis. For each of the developmental stages, individuals in the intermediate stage were considered (2 months and 8 days for TM larvae and pupae respectively; 9 days and 7 days for HI larvae and pupae respectively). Some fatty acids (decanoic, lauric, or myristic acid) were more abundant in HI than in TM. These FAs were produced de novo, indicating that HI produce them from carbohydrates as a source of acetyl-CoA. Hermetia illucens showed a higher level of conjugated linoleic acid (CLA) isomers, a class of fatty acids with positive health effects. In contrast, TM showed a similar fatty acid profile to the plant lipid source (such as soy and sunflower) due to the high level of linoleic acid. Analysis of the triglyceride fraction showed a different affinity for the three glyceride positions. In particular, lauric acid, polyunsaturated fatty acids n-3 and CLA isomers esterified preferentially in sn-2, and therefore were the most adsorbed by the animal during digestion. As for the phospholipids, HI showed a higher level, above all in terms of the phosphatidylethanolamine fraction. Interestingly there was no sphingomyelin in the pupae of both species. The high level of phospholipids is a useful feature for the emulsion of fats in animal feed diets. Lastly, we observed a considerable amount of phytosterol in the sterol profile of both species, which makes these insects a valid alternative to other food sources of plant origin for animal nutrition. We believe that our findings provide new nutritional information for the use of TM and HI in the animal diet.

A lipidomics platform to analyze the fatty acid compositions of non-polar and polar lipid molecular species from plant tissues: Examples from developing seeds and seedlings of pennycress (Thlaspi arvense).

The lipidome comprises the total content of molecular species of each lipid class, and is measured using the analytical techniques of lipidomics. Many liquid chromatography-mass spectrometry (LC-MS) methods have previously been described to characterize the lipidome. However, many lipidomic approaches may not fully uncover the subtleties of lipid molecular species, such as the full fatty acid (FA) composition of certain lipid classes. Here, we describe a stepwise targeted lipidomics approach to characterize the polar and non-polar lipid classes using complementary LC-MS methods. Our "polar" method measures 260 molecular species across 12 polar lipid classes, and is performed using hydrophilic interaction chromatography (HILIC) on a NH2 column to separate lipid classes by their headgroup. Our "non-polar" method measures 254 molecular species across three non-polar lipid classes, separating molecular species on their FA characteristics by reverse phase (RP) chromatography on a C30 column. Five different extraction methods were compared, with an MTBE-based extraction chosen for the final lipidomics workflow. A state-of-the-art strategy to determine and relatively quantify the FA composition of triacylglycerols is also described. This lipidomics workflow was applied to developing, mature, and germinated pennycress seeds/seedlings and found unexpected changes among several lipid molecular species. During development, diacylglycerols predominantly contained long chain length FAs, which contrasted with the very long chain FAs of triacylglycerols in mature seeds. Potential metabolic explanations are discussed. The lack of very long chain fatty acids in diacylglycerols of germinating seeds may indicate very long chain FAs, such as erucic acid, are preferentially channeled into beta-oxidation for energy production.

Self-propelled cellular translocation of Janus-shaped graphene quantum dots: A molecular dynamics simulation and thermodynamic analysis

Although spatially heterogeneous oxidation is pivotal to the cellular translocation process of graphene quantum dots (GQDs), the dynamical road to the thermodynamically stable translocation conformation remains hazy. In this study, we illuminate the bio-interface doctrine involving the cellular translocation of Janus-shaped oxidized GQDs by performing multi-dimensional pathway computations predicated on coupled microsecond-long molecular dynamics and well-tempered metadynamics simulations. The oxidation nanodomains of Janus-shaped GQDs spontaneously yield hydrogen-bonds with polar lipid heads, while their pristine graphene nanodomains hydrophobically associate with nonpolar lipid tails, and thus respond as self-propelled nanomotors across biological membranes. Hydrophobic-associations and hydrogen-bondings are found to be competitively coordinated, which dictates the dynamic pathway and thermodynamic states for cellular translocation, particularly modulating the adaptive self-propelling activity. The translocational phase diagram is drawn, demonstrating that GQDs with moderately square-patterned oxidation and thin thickness facilitate excellent translocation and minimal biological nanotoxicity. Importantly, intermolecular mechanochemistry is discovered to play a crucial role in energy transduction and nanomechanical interactions, which in turn affect the spatial rotation pathways of GQDs, as well as the membrane perturbations. Overall, this study provides an intuitive insight into the dynamics and thermodynamics of spontaneously translocating GQDs, opening up brand-new avenues for developing GQD-enabled nanocarriers or antibiotics.