The role of C18 fatty acids in improving the digestion and retrogradation properties of highland barley starch.

In this study, five C18 fatty acids (FA) with different numbers of double bonds and configurations including stearic acid (SA), oleic acid (OA), elaidic acid (EA), linoleic acid (LA), and α-linolenic acid (ALA), were selected to prepare highland barely starch (HBS)-FA complexes to modulate digestibility and elaborate the underlying mechanism. The results showed that HBS-SA had the highest complex index (34.18 %), relative crystallinity (17.62 %) and single helix content (25.78 %). Furthermore, the HBS-C18 FA complexes were formed by EA (C18 FA with monounsaturated bonds) that had the highest R1047/1022 (1.0509) and lowest full width at half-maximum (FWHM, 20.85), suggesting good short-range ordered structure. Moreover, all C18 FAs could form two kinds of V-type complexes with HBS, which can be confirmed by the results of CLSM and DSC measurements, and all of them showed significantly lower digestibility. HBS-EA possessed the highest resistant starch content (20.17 %), while HBS-SA had the highest slowly digestible starch content (26.61 %). In addition, the inhibition of HBS retrogradation by fatty acid addition was further proven, where HBS-SA gel firmness (37.80 g) and aging enthalpy value were the lowest, indicating the most effective. Overall, compounding with fatty acids, especially SA, could be used as a novel way to make functional foods based on HBS.

Effect of electron beam irradiation pretreatment and different fatty acid types on the formation, structural characteristics and functional properties of starch-lipid complexes.

The effects of different electron beam irradiation doses (2, 4, 8 KGy) and various types of fatty acids (lauric acid, stearic acid, and oleic acid) on the formation, structure, physicochemical properties, and digestibility of starch-lipid complex were investigated. The complexing index of the complexes was higher than 85 %, indicating that the three fatty acids could easily form complexes with starch. With the increase of electron beam irradiation dose, the complexing index increased first and then decreased. The highest complexing index was lauric acid (97.12 %), stearic acid (96.80 %), and oleic acid (97.51 %) at 2 KGy radiation dose, respectively. Moreover, the microstructure, crystal structure, thermal stability, rheological properties, and starch solubility were analyzed. In vitro digestibility tests showed that adding fatty acids could reduce the content of hydrolyzed starch, among which the resistant starch content of the starch-oleic acid complex was the highest (54.26 %). The lower dose of electron beam irradiation could decrease the digestibility of starch and increase the content of resistant starch.

Binary and ternary complex formation and characterization of artemisinin with sulfobutyl ether ß-cyclodextrin and oleic acid.

Drug-resistant malaria is a global risk to the modern world. Artremisinin (ART) is one of the drugs of choice against drug-resistant (malaria) which is practically insoluble in water. The objective of our study was to improve the solubility of artemisinin (ART) via development of binary complexes of ART with sulfobutylether ß-cyclodextrins (SBE7 ß-CD), sulfobutylether ß-cyclodextrins (SBE7 ß-CD) and oleic acid (ternary complexes). These are prepared in various drugs to excipients ratios by physical mixing (PM) and solvent evaporation (SE) methods. Characterizations were achieved by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and attenuated total reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. The aqueous-solubility in binary complexes was 12-folds enhanced than ternary complexes. Dissolution of binary and ternary complexes of artemisinin in simulated gastric fluid (pH 1.6) was found highest and 35 times higher for ternary SECx. The crystallinity of artemisinin was decreased in physical mixtures (PMs) while SECx exhibited displaced angles. The attenuated-intensity of SECx showed least peak numbers with more displaced-angles. SEM images of PMs and SECx showed reduced particle size in binary and ternary systems as compared to pure drug-particles. ATR-FTIR spectra of binary and ternary complexes revealed bonding interactions among artemisinin, SBE7 ß-CD and oleic acid.

Fabrication of Human Milk Fat Substitute: Based on the Similarity Evaluation Model and Computer Software.

We aimed to obtain the optimal formula for human milk fat substitute (HMFS) through a combination of software and an evaluation model and further verify its practicability through an animal experiment. The results showed that a total of 33 fatty acid (FA) and 63 triglyceride (TAG) molecular species were detected in vegetable oils. Palmitic acid, oleic acid, linoleic acid, 18:1/16:0/18:1, 18:2/16:0/18:2, 18:1/18:1/18:1 and 18:1/18:2/18:1, were the main molecular species among the FAs and TAGs in the vegetable oils. Based on the HMFS evaluation model, the optimal mixed vegetable oil formula was blended with 21.3% palm oil, 2.8% linseed oil, 2.6% soybean oil, 29.9% rapeseed oil and 43.4% maize oil, with the highest score of 83.146. Moreover, there was no difference in the weight, blood routine indices or calcium and magnesium concentrations in the feces of the mice between the homemade mixed vegetable oil (HMVO) group and the commercial mixed vegetable oil (CMVO) group, while nervonic acid (C24:1) and octanoic acid (C8:0) were absorbed easily in the HMVO group. Therefore, these results demonstrate that the mixing of the different vegetable oils was feasible via a combination of computer software and an evaluation model and provided a new way to produce HMFS.

Exploration of Polysaccharides from Phyllanthus emblica: Isolation, Identification, and Evaluation of Antioxidant and Anti-Glycolipid Metabolism Disorder Activities.

Phyllanthus emblica is a natural medicinal herb with diverse bioactivities. Certain extracts from this herb have been confirmed to possess anti-glycolipid metabolic disorder activity. To further develop its utility value and explore its potential in combating glycolipid metabolic disorders, we designed a series of experiments to investigate the structure, antioxidant activity, and anti-glycolipid metabolic disorder activity of Phyllanthus emblica polysaccharides. In this study, we extracted and purified polysaccharides from Phyllanthus emblica and thoroughly analyzed their structure using various techniques, including NMR, methylation analysis, and surface-enhanced Raman spectroscopy. We investigated the hypolipidemic and anti-glycolipid metabolism disorder activity of Phyllanthus emblica polysaccharides for the first time utilizing oleic acid (OA) and advanced glycation end products (AGEs) as inducers. Additionally, the antioxidant activity of Phyllanthus emblica polysaccharides was assessed in vitro. These findings lay the groundwork for future investigations into the potential application of Phyllanthus emblica polysaccharides as an intervention for preventing and treating diabetes.

Hyaluronic acid-oleylamine and chitosan-oleic acid conjugate-based hybrid nanoparticle delivery via. dissolving microneedles for enhanced treatment efficacy in localized breast cancer.

Microneedle technology offers a minimally invasive treatment strategy to deliver chemotherapeutics to localized tumors. Amalgamating the surface functionalized nanoparticles with microneedle technology can potentially deliver drugs directly to tumors and subsequently target cancer cells via, overexpressed receptors on the cell surface, thereby enhancing the treatment efficacy while reducing side effects. Here, we report cetuximab anchored hyaluronic acid-oleylamine and chitosan-oleic acid-based hybrid nanoparticle (HA-OA/CS-OA NPT)-loaded dissolving microneedles (MN) for targeted delivery of cabazitaxel (CBT) in localized breast cancer tumor. The HA-OA/CS-OA NPT was characterized for their size, surface charge, morphology, physicochemical characteristics, drug release behavior, and in vitro anti-cancer efficacy. The HA-OA/CS-OA NPT were of ~125 nm size, showed enhanced cytotoxicity and cellular uptake, and elicited a superior apoptotic response against MDA-MB-231 cells. Subsequently, the morphology and physicochemical characteristics of HA-OA/CS-OA NPT-loaded MN were also evaluated. The fabricated microneedles were of ~550 µm height and showed loading of nanoparticles equivalent to ~250 µg of CBT. The ex vivo skin permeation study revealed fast dissolution of microneedles upon hydration, while the drug permeation across the skin exhibited ~4-fold improvement in comparison to free drug-loaded MN. In vivo studies performed on DMBA-induced breast cancer in female SD rats showed a marked reduction in tumor volume after administration of drug and nanoparticle-loaded microneedles in comparison to intravenous administration of free drug. However, the HA-OA/CS-OA NPT-MN showed the highest tumor reduction and survival rate, with the lowest body weight reduction in comparison to other treatment groups, indicating its superior efficacy and low systemic toxicity. Overall, the dissolving microneedle-mediated delivery of targeted nanoparticles loaded with chemotherapeutics offers a superior alternative to conventional intravenous chemotherapy.

Esterification of black bean anthocyanins with unsaturated oleic acid, and application characteristics of the product.

Esterification of anthocyanins with saturated fatty acids have been widely investigated, while that with unsaturated fatty acids is little understood. In this study, crude extract (purity âˆ¼ 35 %) of cyanidin-3-O-glucoside (C3G) from black bean seed coat was utilized as reaction substrate, and enzymatically acylated with unsaturated fatty acid (oleic acid). Optimization of various reaction parameters finally resulted in the highest acylation rate of 54.3 %. HPLC-MS/MS and NMR analyses elucidated the structure of cyanidin-3-O-glucoside-oleic acid ester (C3G-OA) to be cyanidin-3-O-(6″-octadecene)-glucoside. Introduction of oleic acid into C3G improved the lipophilicity, antioxidant ability, and antibacterial activity. Further, the color and substance stability analyses showed that the susceptibility of C3G and C3G-OA to different thermal, peroxidative, and illuminant treatments were highly pH dependent, which suggested individual application guidelines. Moreover, C3G-OA showed lower toxicity to normal cell (QSG-7701) and better inhibitory effect on the proliferation of HepG2 cells than C3G, which indicated its potential anti-tumor bioactivity.

Design of oleic acid/alkyl glycoside composite vesicles as cosmetics carrier: stability, skin permeability and antioxidant activity.

Biocompatible fatty acids are natural biological materials which exhibit widespread biomedical applications. Nevertheless, their application in vesicle forms is hampered by strong pH sensitivity and poor stability to changes in ionic strength, temperature, and storage. In the investigation, the incorporation of alkyl glycoside (APG), a surfactant with non-ionic properties, into the oleic acid (OA) vesicles was undertaken as a means to address this issue. The newly formed OA/APG composite vesicles form in a pH range of between 5.4 and 7.4, which is close to the pH range of the physiological environment. The stability studies results showed that the OA/APG composite vesicles have excellent stability in terms of ionic strengths, temperature and storage. The formation of NAR-loaded OA/APG composite vesicles was demonstrated through FT-IR, DSC and XRD. In vitro topical delivery and skin retention studies confirmed that the composite vesicles improve skin permeation rate and have better skin permeation behavior. Antioxidant activity experiments confirmed that the antioxidant effect composite vesicles were significantly increased as compared to the naringenin (NAR). This finding has theoretical implications for the use of drug-loaded fatty acid vesicles in cosmetics industries and topical delivery systems.

HAMLET in human milk is resistant to digestion and carries essential free long chain polyunsaturated fatty acids and oleic acid.

The oleic acid/alpha-lactalbumin complex HAMLET (human alpha-lactalbumin made lethal to tumors) is cytotoxic to various cancerous cell lines and is assembled from alpha-lactalbumin (ALA) and free oleic acid (OA). HAMLET is also cytotoxic to normal immature intestinal cells. It remains unclear if HAMLET, experimentally assembled with OA and heat, can spontaneously assemble in frozen human milk over time. To approach this issue, we used a set of timed proteolytic experiments to evaluate the digestibility of HAMLET and native ALA. The purity of HAMLET in human milk was confirmed by ultra high performance liquid chromatography coupled to tandem mass spectrometry and western blot to resolve the ALA and OA components. Timed proteolytic experiments were used to identify HAMLET in whole milk samples. Structural characterization of HAMLET was performed by Fournier transformed infrared spectroscopy and indicated a transformation of secondary structure with increased alpha-helical character of ALA upon binding to OA.

Impact of de-branched starch molecules and fatty acid complexes on the attenuation of ageing-induced cognitive impairment.

BACKGROUND: Ageing and associated cognitive impairments are becoming serious issues around the world. In this study, the physiological properties of three kinds of complexes of fatty acid (capric, stearic and oleic acid, respectively) and de-branched starch molecules were investigated via a d-galactose-induced ageing model. This study revealed differences in the regulation of cognitive impairment and brain damage following intervention of different complexes, which might highlight a potent approach for the prevention of this chronic disease. RESULTS: Data indicated that three complexes improved response time and cognitive function and the bio-parameter markers associated with oxidative stress in ageing rats. Among them, the complexes prepared from de-branched starch-oleic acid showed a greater improvement compared to others. In addition, de-branched starch-capric acid complex showed a higher improvement in the morphology of colon cells and hippocampal neuronal cells. The consumption of de-branched starch-capric acid and -oleic acid complexes generated more short-chain fatty acids in the gut. More importantly, the complexation of de-branched starch with either caprate or stearate enhanced gut Akkermansia. Therefore, it was proposed that the richness in Akkermansia and gut metabolites might be associated with reduced damage of the hippocampal neuronal cells induced by the ageing progress. Moreover, the AMPK (AMP-activated protein kinase) pathway was activated in liver in de-branched starch-capric acid complex diet. In summary, de-branched starch-capric acid complex exhibited a greater effect on the attenuation of ageing-induced cognitive impairment. CONCLUSION: This study might highlight a new approach for intervening in the cognitive impairment during the ageing progress via a food supply. © 2023 Society of Chemical Industry.

Conjugates of 1,3- and 1,2-Acylglycerols with Stigmasterol: Synthesis, NMR Characterization, and Impact on Lipid Bilayers.

The main aim of research was synthesis and spectroscopic characterization of new conjugates in which stigmasterol was linked via carbonate or succinyl linker with 1,3- and 1,2-acylglycerols of palmitic and oleic acid. Acylglycerols containing stigmasterol residue at internal position have been synthesized from 2-benzyloxypropane-1,3-diol or dihydroxyacetone. Their asymmetric counterparts containing stigmasterol residue attached to sn-3 position have been obtained from (S)-solketal. Eight synthesized conjugates were used to create the liposomes as nanocarriers of phytosterols to increase their stability and protect them from degradation during thermal-oxidative treatments. Fluorimetric and ATR-FTIR methods were used to determine the impact of synthesized conjugates on the physicochemical properties of the lipid bilayer. The results indicate that conjugates with palmitic acid are better candidates for use as the potential stigmasterol nanocarriers compared to those with oleic acid because they increase the stiffness of the lipid bilayer and temperature of the main phase transition. The obtained results are the first step in designing of stigmasterol-enriched liposomal carriers with higher thermo-oxidative stability for their potential use in the food industry.

Improved antioxidant activity of rutin via lipase-mediated esterification with oleic acid.

BACKGROUND: Oxidation is a major problem for oils and fats, which can be mitigated by antioxidants. Rutin has excellent antioxidant activity, but its poor lipid solubility greatly limits its practical application. In this study, an efficient enzymatic synthesis route of lipophilic rutin ester was established using oleic acid as an acyl donor, and the antioxidant potential of rutin oleate was evaluated for the first time by proton (1 H) nuclear magnetic resonance (NMR) spectroscopy. RESULTS: The synthesized product was finally identified as rutin oleate by Fourier transform infrared, high-performance liquid chromatography-mass spectrometry, and 1 H, carbon-13, and DEPT-135 NMR analyses, and the acylation site was the 4‴-OH of the rhamnose group in the rutin molecule. The maximum conversion was over 93% after 48 h of reaction using Novozym 435 as catalyst under the best conditions among these tests. The conversion of rutin ester decreased with the increase of carbon chain length and the number of carbon-carbon double bonds of the fatty acid molecule. Most importantly, rutin oleate exhibited antioxidant capacity comparable to butylated hydroxytoluene and its counterparts (rutin and oleic acid) at low temperatures (60° C), but had a significant advantage at high temperatures (120° C). CONCLUSION: The antioxidant activity of rutin was significantly enhanced by lipase-mediated esterification with oleic acid. Therefore, rutin oleate could be further developed as a novel antioxidant for use in oil- and fat-based foods. © 2023 Society of Chemical Industry.

Effects and Mode of Action of Oleic Acid and Tween 80 on Skin Permeation of Disulfiram.

Oral disulfiram (DSF) has been used clinically for alcohol dependence and recently has been found to have antitumor activity. A transdermal delivery system would be useful for maintaining drug concentration and reducing the frequency of administration of DSF for cancer treatment. Penetrating the stratum corneum (SC) barrier is a challenge to the transdermal delivery of DSF. Therefore, we investigated the promoting effects and mechanism of action of the combination of oleic acid (OA) and Tween 80 on the skin permeation of DSF. Hairless mouse skin was exposed to OA and Tween 80, combined in various ratios (1 : 0, 2 : 1, 1 : 1, 1 : 2, and 0 : 1). A permeation experiment was performed, and total internal reflection IR spectroscopic measurements, differential scanning calorimetry, and synchrotron radiation X-ray diffraction measurements were taken of the SC with each applied formulation. The combination of OA and Tween 80 further enhanced the absorption-promoting effect of DSF, compared with individual application. The peak of the CH2 inverse symmetric stretching vibration near the skin surface temperature was shifted by a high frequency due to the application of OA, and DSF solubility increased in response to Tween 80. We believe that the increased fluidity of the intercellular lipids due to OA and the increased solubility of DSF due to Tween 80 promoted the absorption of DSF. Our study clarifies the detailed mechanism of action of the skin permeation and promoting effect of DSF through the combined use of OA and Tween 80, contributing to the development of a transdermal preparation of DSF.

Competition at the Bio-nano Interface: A Protein, a Polysaccharide, and a Fatty Acid Adsorb onto Magnetic Nanoparticles.

Magnetic nanoparticles are an attractive bioseparation tool due to their magnetic susceptibility and high adsorption capacity for different types of molecules. A major challenge for separation is to generate selectivity for a target molecule, or for a group of molecules in complex environments such as cell lysates. It is crucial to understand the factors that determine the targets' adsorption behavior in mixtures for triggering intended interactions and selectivity. Here we use a model system containing three molecules, each of them a common representative of the more abundant types of macromolecules in living systems: sodium oleate (SO), a fatty acid; bovine serum albumin (BSA), a protein; and dextran, a polysaccharide. Our results show that (a) the BSA adsorption capacity on the iron oxide material depends markedly on the pH, with the maximum capacity at the pI of the protein (0.39 g gMNP-1 ); (b) sodium oleate, a strongly negatively charged molecule, an organic anion, renders a maximum adsorption capacity of 0.40 g gMNP-1, even at pHs at which oleate as well as the nanoparticle surface are negatively charged; (c) the adsorbed masses of dextran, a neutral sugar, are lower than for the other two molecules, between 0.09 and 0.13 g gMNP-1, regardless of the system's pH. We observe an unexpected behavior in mixtures: SO completely prevents the adsorption of BSA, and dextran decreases the adsorption of the other competitors, SO and BSA, while adsorbing at the same capacities, unaffected by either the presence of the other two molecules or the pH. BSA does not decrease the oleate adsorption capacity. We demonstrate the essential role of pH in the adsorption of BSA (a protein) and SO (a fatty acid), as well as its impact in the structural organization of the oleate molecules in water. Moreover, we present exciting data on the adsorption of the molecules in competition, revealing the need to focus on interaction studies in more complex environments. This study attempts to open the scope of the current research of bio-nano interactions to not only proteins but also to mixtures, and generally to molecules with other physicochemical characteristics. Furthermore, we contribute to the understanding of multicomponent systems with the vision set in enhancing biomass exploitation and biofractionation processes.

Electrodynamic balance-mass spectrometry reveals impact of oxidant concentration on product composition in the ozonolysis of oleic acid.

The chemical and physical properties of atmospheric aerosol particles change upon oxidative ageing, influencing their interaction with radiation, their propensity to serve as nuclei for cloud condensation and ice formation, and their adverse effects on human health. The investigation of atmospheric aerosol oxidation processes is complicated by low oxidant concentrations and long timescales, which are difficult to represent in laboratory studies. Experimental work often attempts to compensate for short timescales with elevated concentrations of oxidative agents, assuming that the ageing progress depends only on the oxidant exposure, i.e. on the product of oxidant concentration and time, [Ox] × t, and not on [Ox] or t independently. The application of electrodynamic balance-mass spectrometry of single particles allows the validity of this assumption to be investigated, since it provides information on the molecular composition of aerosol particles for a wide range of reaction durations under well-defined oxidation conditions. Here, we demonstrate the capabilities of a new setup on levitated oleic acid droplets reacting with ozone at mixing ratios of 0.2 and 15 ppm, i.e. spanning almost two orders of magnitude in [Ox]. We show that the reactive removal of oleic acid can be accurately expressed as a function of ozone exposure [Ox] × t, whereas the product concentrations depend on [Ox] and t independently. As the underlying reason for the breakdown of the exposure metric, we suggest a competition between evaporation of volatile first-generation products and their accretion reactions with reactive Criegee intermediates, converting them into low-volatility dimers and oligomers. This hypothesis is supported by kinetic model simulations using the aerosol process model KM-SUB, which explicitly resolves the competition between evaporation and secondary chemistry as a function of the experimental timescale and ozone mixing ratio. The model successfully reproduces final product distributions. The findings are further supported by the recorded changes of droplet sizes during oxidation. As a heuristic, the breakdown of the exposure metric in a chemical reaction system is possible, when competition between first- and second-order processes of reactive intermediates determines important system properties.

Optical tweezer platform for the characterization of pH-triggered colloidal transformations in the oleic acid/water system.

HYPOTHESIS: Soft colloidal particles that respond to their environment have innovative potential for many fields ranging from food and health to biotechnology and oil recovery. The in situ characterisation of colloidal transformations that triggers the functional response remain a challenge. EXPERIMENTS: This study demonstrates the combination of an optical micromanipulation platform, polarized optical video microscopy and microfluidics in a comprehensive approach for the analysis of pH-driven structural transformations in emulsions. The new platform, together with synchrotron small angle X-ray scattering, was then applied to research the food-relevant, pH-responsive, oleic acid in water system. FINDINGS: The experiments demonstrate structural transformations in individual oleic acid particles from micron-sized onion-type multilamellar oleic acid vesicles at pH 8.6, to nanostructured emulsions at pH < 8.0, and eventually oil droplets at pH < 6.5. The smooth particle-water interface of the onion-type vesicles at pH 8.6 was transformed into a rough particle surface at pH below 7.5. The pH-triggered changes of the interfacial tension at the droplet-water interface together with mass transport owing to structural transformations induced a self-propelled motion of the particle. The results of this study contribute to the fundamental understanding of the structure-property relationship in pH-responsive emulsions for nutrient and drug delivery applications.

Different Metabolism and Toxicity of TRANS Fatty Acids, Elaidate and Vaccenate Compared to Cis-Oleate in HepG2 Cells.

Trans fatty acids (TFAs) are not synthesized in the human body but are generally ingested in substantial amounts. The widespread view that TFAs, particularly those of industrial origin, are unhealthy and contribute to obesity, cardiovascular diseases and diabetes is based mostly on in vivo studies, and the underlying molecular mechanisms remain to be elucidated. Here, we used a hepatoma model of palmitate-induced lipotoxicity to compare the metabolism and effects of the representative industrial and ruminant TFAs, elaidate and vaccenate, respectively, with those of cis-oleate. Cellular FAs, triacylglycerols, diacylglycerols and ceramides were quantitated using chromatography, markers of stress and apoptosis were assessed at mRNA and protein levels, ultrastructural changes were examined by electron microscopy and viability was evaluated by MTT assay. While TFAs were just slightly more damaging than oleate when applied alone, they were remarkably less protective against palmitate toxicity in cotreatments. These differences correlated with their diverse incorporation into the accumulating diacylglycerols and ceramides. Our results provide in vitro evidence for the unfavorable metabolic features and potent stress-inducing character of TFAs in comparison with oleate. These findings strengthen the reasoning against dietary trans fat intake, and they can also help us better understand the molecular mechanisms of lipotoxicity.

Oleic acid/oleylamine ligand pair: a versatile combination in the synthesis of colloidal nanoparticles.

A variety of colloidal chemical approaches has been developed in the last few decades for the controlled synthesis of nanostructured materials in either water or organic solvents. Besides the precursors, the solvents, reducing agents, and the choice of surfactants are crucial for tuning the composition, morphology and other properties of the resulting nanoparticles. The ligands employed include thiols, amines, carboxylic acids, phosphines and phosphine oxides. Generally, adding a single ligand to the reaction mixture is not always adequate to yield the desired features. In this review, we discuss in detail the role of the oleic acid/oleylamine ligand pair in the chemical synthesis of nanoparticles. The combined use of these ligands belonging to two different categories of molecules aims to control the size and shape of nanoparticles and prevent their aggregation, not only during their synthesis but also after their dispersion in a carrier solvent. We show how the different binding strengths of these two molecules and their distinct binding modes on specific facets affect the reaction kinetics toward the production of nanostructures with tailored characteristics. Additional functions, such as the reducing function, are also noted, especially for oleylamine. Sometimes, the carboxylic acid will react with the alkylamine to form an acid-base complex, which may serve as a binary capping agent and reductant; however, its reducing capacity may range from lower to much lower than that of oleylamine. The types of nanoparticles synthesized in the simultaneous presence of oleic acid and oleylamine and discussed herein include metal oxides, metal chalcogenides, metals, bimetallic structures, perovskites, upconversion particles and rare earth-based materials. Diverse morphologies, ranging from spherical nanoparticles to anisotropic, core-shell and hetero-structured configurations are presented. Finally, the relation between tuning the resulting surface and volume nanoparticle properties and the relevant applications is highlighted.

Multiphase Ozonolysis of Oleic Acid-Based Lipids: Quantitation of Major Products and Kinetic Multilayer Modeling.

Commonly found in atmospheric aerosols, cooking oils, and human sebum, unsaturated lipids rapidly decay upon exposure to ozone, following the Criegee mechanism. Here, the gas-surface ozonolysis of three oleic acid-based compounds was studied in a reactor and indoors. Under dry conditions, quantitative product analyses by 1H NMR indicate up to 79% molar yield of stable secondary ozonides (SOZs) in oxidized triolein and methyl oleate coatings. Elevated relative humidity (RH) significantly suppresses the SOZ yields, enhancing the formation of condensed-phase aldehydes and volatile C9 products. Along with kinetic parameters informed by molecular dynamics simulations, these results were used as constraints in a kinetic multilayer model (KM-GAP) simulating triolein ozonolysis. Covering a wide range of coating thicknesses and ozone levels, the model predicts a much faster decay near the gas-lipid interface compared to the bulk. Although the dependence of RH on SOZ yields is well predicted, the model overestimates the production of H2O2 and aldehydes. With negligible dependence on RH, the product composition for oxidized oleic acid is substantially affected by a competitive reaction between Criegee intermediates (CIs) and carboxylic acids. The resulting α-acyloxyalkyl hydroperoxides (α-AAHPs) have much higher molar yields (29-38%) than SOZs (12-16%). Overall, the ozone-lipid chemistry could affect the indoor environment through "crust" accumulation on surfaces and volatile organic compound (VOC) emission. In the atmosphere, the peroxide formation and changes in particle hygroscopicity may have effects on climate. The related health impacts are also discussed.

Combination of Oleic Acid and the gp41 Fusion Peptide Switches the Phosphatidylethanolamine-Induced Membrane Fusion Mechanism from a Nonclassical to a Classical Stalk Model.

Membrane fusion is considered to be one of the crucial processes for the existence of eukaryotes and the entry of enveloped viruses into host cells. The fusion mechanism depends on the lipid composition of the membrane as well as the properties of fusion proteins or peptides. The gp41 fusion peptide from the human immunodeficiency virus (HIV) is known to catalyze membrane fusion by altering the physical properties of the membrane. Earlier, we demonstrated that a membrane containing 30 mol % phosphatidylethanolamine (PE) circumvents the classical stalk model because of its intrinsic negative curvature. In this work, we demonstrated how the gp41 fusion peptide influences the fusion mechanism of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dioleoyl-sn-glycero-3-phos-pho¬ethanolamine (DOPE) (70/30 mol %) membranes. We further evaluated the effect of the same peptide on the mechanism of fusion for membranes containing 30 mol % PE and a fatty acid with an intrinsic positive curvature (oleic acid (OA)). Our results show that gp41 switches the fusion mechanism from a nonclassical to a classical stalk model when membranes contain OA, but fails to do so for DOPC/DOPE membranes. This could be due to the extreme influence of the intrinsic negative curvature of PE, which is partially downregulated in the presence of OA.