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Results for “LIPIDS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Impaired lipid accumulation in the liver of Tsc2-heterozygous mice during liver regeneration

Highlights: •Tuberin phosphorylation correlated with mTOR activation in early liver regeneration. •Liver regeneration in the Tsc2+/− mice was not enhanced. •The Tsc2+/− livers failed to accumulate lipid bodies during liver regeneration. •Mortality rate increased in Tsc2+/− mice after partial hepatectomy. •Tuberin plays a critical role in hepatic lipid accumulation to support regeneration. -- Abstract: Tuberin is a negative regulator of mTOR pathway. To investigate the function of tuberin during liver regeneration, we performed 70% hepatectomy on wild-type and Tsc2+/− mice. We found the tuberin phosphorylation correlated with mTOR activation during early liver regeneration in wild-type mice. However, liver regeneration in the Tsc2+/− mice was not enhanced. Instead, the Tsc2+/− livers failed to accumulate lipid bodies, and this was accompanied by increased mortality. These findings suggest that tuberin plays a critical role in liver energy balance by regulating hepatocellular lipid accumulation during early liver regeneration. These effects may influence the role of mTORC1 on cell growth and proliferation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Overexpression of Jazf1 reduces body weight gain and regulates lipid metabolism in high fat diet

Highlights: • The expression of Jazf1 in the liver suppressed lipid accumulation. • Jazf1 significantly increases transcription of fatty acid synthase. • Jazf1 plays a critical role in the regulation of energy and lipid homeostasis. • Jazf1 associates the development of metabolic disorder. • Jazf1 may provide a new therapeutic target in the management of metabolic disorder. - Abstract: Jazf1 is a 27 kDa nuclear protein containing three putative zinc finger motifs that is associated with diabetes mellitus and prostate cancer; however, little is known about the role that this gene plays in regulation of metabolism. Recent evidence indicates that Jazf1 transcription factors bind to the nuclear orphan receptor TR4. This receptor regulates PEPCK, the key enzyme involved in gluconeogenesis. To elucidate Jazf1’s role in metabolism, we fed a 60% fat diet for up to 15 weeks. In Jazf1 overexpression mice, weight gain was found to be significantly decreased. The expression of Jazf1 in the liver also suppressed lipid accumulation and decreased droplet size. These results suggest that Jazf1 plays a critical role in the regulation of lipid homeostasis. Finally, Jazf1 may provide a new therapeutic target in the management of obesity and diabetes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Human alpha beta hydrolase domain containing protein 11 and its yeast homolog are lipid hydrolases

Mammalian alpha/beta hydrolase domain (ABHD) family of proteins have emerged as key regulators of lipid metabolism and are found to be associated with human diseases. Human α/β-hydrolase domain containing protein 11 (ABHD11) has recently been predicted as a potential biomarker for human lung adenocarcinoma. In silico analyses of the ABHD11 protein sequence revealed the presence of a conserved lipase motif GXSXG. However, the role of ABHD11 in lipid metabolism is not known. To understand the biological function of ABHD11, we heterologously expressed the human ABHD11 in budding yeast, Saccharomyces cerevisiae. In vivo [{sup 14}C]acetate labeling of cellular lipids in yeast cells overexpressing ABHD11 showed a decrease in triacylglycerol content. Overexpression of ABHD11 also alters the molecular species of triacylglycerol in yeast. Similar activity was observed in its yeast homolog, Ygr031w. The role of the conserved lipase motif in the hydrolase activity was proven by the mutation of all conserved amino acid residues of GXSXG motif. Collectively, our results demonstrate that human ABHD11 and its yeast homolog YGR031W have a pivotal role in the lipid metabolism. - Highlights: • Overexpression of ABHD11 protein and its yeast homolog Ygr031w cause a reduction in triacylglycerol levels in yeast. • The reduction in triacylglycerol is due to the presence of lipase motif GXSXG. • Overexpression of ABHD11 and Ygr031w alters the molecular species of triacylglycerol.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Green pretreatment strategies for enhanced microbial lipid fermentation and synergistic high-quality lignin recovery for next-generation integrated biorefineries

Miscanthus × giganteus (Mxg) is a warm-season perennial grass being commercialized as a biomass feedstock for temperate farms. Three process strategies were compared for converting Mxg into single-cell oil and extracted lignin intermediates, as hydrothermal (HT) processing and two natural deep eutectic solvents (NADES), ChCl:LA (choline chloride:lactic acid) and ChCl:Gly (choline chloride:glycerol). Pretreatments were performed at 10% and 50% solids loading at 140 °C, 2 h; HT: 190 °C, 10 min. Enzymatic hydrolysates, generated at 10% solids using washed and unwashed biomass, were evaluated for microbial lipid production. Maximum glucose conversions from washed biomass reached 83.5% (ChCl:LA), 52.7% (ChCl:Gly), and 74.0% (HT). Remarkably, NADES-derived hydrolysates effectively replaced refined sugars for the cultivation of the oleaginous yeast Rhodotorula toruloides, achieving ∼51% higher biomass (OD 90.7) and lipid titers of 19.36 g/L within 45 h using a two-stage fermentation strategy. Lipid contents ranged from 34.5–44.5% dry weight, demonstrating reduced reliance on purified sugars. Beyond carbohydrate valorization, ChCl:LA pretreatment enabled high-purity lignin recovery (>89%) in a lignin-first strategy. Structural analyses (2D-HSQC and ³¹P NMR) showed syringyl (78.15%), guaiacyl (15.15%), and p-hydroxyphenyl (6.41%) units, with higher phenolic hydroxyl content (0.91 mmol/g) and a lower S/G ratio (0.19) than HT lignin (0.87 mmol/g, S/G 0.22). These attributes favor downstream lignin depolymerization into low-molecular-weight aromatics. Overall, NADES pretreatment simultaneously enhances microbial lipid yields and recovers high-quality lignin, advancing the economic feasibility of renewable diesel and sustainable aviation fuel (SAF) production from bioenergy crops within an integrated biorefinery framework.

2D HSQC↗
DOE OSTI2025

Mixed lipid bilayers enable enhanced stability and activity retention of Lipase A in low-pH environments

Lipase A (LipA) from Bacillus subtilis is a versatile and industrially relevant enzyme, but its activity is compromised under acidic conditions due to aggregation and deactivation. In this study, we investigated the use of mixed lipid bilayers to stabilize and improve activity retention of LipA at low pH. Attachment to lipid bilayers, particularly those containing cationic lipids, greatly enhanced the long-term stability of LipA in acidic conditions while also leading to improvements in activity. Tethering to cationic bilayers not only shifted the apparent pH activity profile toward more acidic conditions, but also significantly enhanced activity retention upon incubation at pH 6. Notably, this protective effect persisted even without direct tethering, indicating that reversible, non-covalent interactions with the bilayer surface are sufficient for long-term stability. Circular dichroism further revealed that the secondary structure of LipA was retained, while dynamic light scattering suggested that activity loss in solution was primarily due to aggregation of the native state. Together, these findings support a model in which lipid bilayers mitigate aggregation and stabilize LipA through transient interactions and electrostatic modulation of the local surface environment. Furthermore, this approach exemplifies a simple, tether-free strategy for enhancing enzyme performance in acidic or destabilizing conditions, with implications for biocatalysis, biosensing, and therapeutic delivery.

Biocatalysis↗
DOE OSTI2025

Highly tail-asymmetric lipids interdigitate and cause bidirectional ordering

Phospholipids form structurally and compositionally diverse membranes. A less studied type of compositional diversity involves phospholipid tail variety. Some phospholipids contain two acyl tails which differ in length. These tail-asymmetric lipids are shown to contribute to temperature sensitivity, oxygen adaptability, and membrane fluidity. Membranes of a highly virulent intracellular bacterium, Francisella tularensis, contain highly tail-asymmetric 1-lignoceroyl-2-decanoyl-sn-glycero-3-phosphatidylethanolamine (XJPE) lipids which were previously shown to inhibit inflammatory responses in host cells. XJPE tails have unusually high asymmetry, and how they contribute to membrane properties on a molecular level is unknown. Here, we use small angle X-ray scattering and molecular dynamics simulations to investigate how varying XJPE ratios alters properties of simple membranes. Our results demonstrate that at high concentration they promote liquid-to-gel transition in otherwise liquid membranes, while at low concentration they are tolerated well, minimally altering membrane properties. In liquid membranes, XJPE lipids dynamically adopt two main conformations; with the long tail extended into the opposing leaflet or bent-back residing in its own leaflet. When added to both leaflets XJPE primarily adopts an extended confirmation, while asymmetric addition results in more bent-back orientations. The former increases tail ordering and the latter decreases it. XJPE tails adopt different conformations that induce composition- and leaflet-dependent bidirectional effect on membrane fluidity and this suggests that Francisella tularensis could use tail asymmetry to facilitate vesicle fusion and destabilize host cells. The effect of tail-asymmetric lipids on complex membranes should be further investigated to reveal the regulatory roles of high tail asymmetry.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Lipid droplets in plants and algae: Distribution, formation, turnover and function

We report plant oils represent an energy-rich and carbon-dense group of hydrophobic compounds. These oils are not only of economic interest, but also play important, fundamental roles in plant and algal growth and development. The subcellular storage compartments of plant lipids, referred to as lipid droplets (LDs), have long been considered relatively inert oil vessels. However, research in the last decade has revealed that LDs play far more dynamic roles in plant biology than previously appreciated, including transient neutral lipid storage, membrane remodeling, lipid signaling, and stress responses. Here we discuss recent developments in the understanding of LD formation, turnover and function in land plants and algae.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Fetal rat metabonome alteration by prenatal caffeine ingestion probably due to the increased circulatory glucocorticoid level and altered peripheral glucose and lipid metabolic pathways

The aims of this study were to clarify the metabonome alteration in fetal rats after prenatal caffeine ingestion and to explore the underlying mechanism pertaining to the increased fetal circulatory glucocorticoid (GC). Pregnant Wistar rats were daily intragastrically administered with different doses of caffeine (0, 20, 60 and 180 mg/kg) from gestational days (GD) 11 to 20. Metabonome of fetal plasma and amniotic fluid on GD20 were analyzed by {sup 1}H nuclear magnetic resonance-based metabonomics. Gene and protein expressions involved in the GC metabolism, glucose and lipid metabolic pathways in fetal liver and gastrocnemius were measured by real-time RT-PCR and immunohistochemistry. Fetal plasma metabonome were significantly altered by caffeine, which presents as the elevated α- and β‐glucose, reduced multiple lipid contents, varied apolipoprotein contents and increased levels of a number of amino acids. The metabonome of amniotic fluids showed a similar change as that in fetal plasma. Furthermore, the expressions of 11β-hydroxysteroid dehydrogenase 2 (11β-HSD-2) were decreased, while the level of blood GC and the expressions of 11β-HSD-1 and glucocorticoid receptor (GR) were increased in fetal liver and gastrocnemius. Meanwhile, the expressions of insulin-like growth factor 1 (IGF-1), IGF-1 receptor and insulin receptor were decreased, while the expressions of adiponectin receptor 2, leptin receptors and AMP-activated protein kinase α2 were increased after caffeine treatment. Prenatal caffeine ingestion characteristically change the fetal metabonome, which is probably attributed to the alterations of glucose and lipid metabolic pathways induced by increased circulatory GC, activated GC metabolism and enhanced GR expression in peripheral metabolic tissues. -- Highlights: ► Prenatal caffeine ingestion altered the metabonome of IUGR fetal rats. ► Caffeine altered the glucose and lipid metabolic pathways of IUGR fetal rats. ► Prenatal caffeine ingestion induced GC metabolic activation in IUGR fetal rats.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Tris(1,3-dichloro-2-propyl) phosphate perturbs the expression of genes involved in immune response and lipid and steroid metabolism in chicken embryos

We previously demonstrated that in ovo exposure to the flame retardant tris(1,3-dichloro-2-propyl) phosphate (TDCPP) decreased plasma thyroxine levels, reduced growth parameters, and decreased gallbladder size in chicken embryos. In the current study DNA microarrays were used to evaluate global mRNA expression in liver tissue of male chicken embryos that exhibited the above mentioned effects. Injected doses were dimethyl sulfoxide vehicle control, 7.6 or 45 μg TDCPP/g egg. TDCPP caused significant changes in the expression of five genes at the low dose and 47 genes at the high dose (False Discovery Rate p ≤ 0.1, fold change ≥ 1.5). The gene expression analysis suggested a compromised immune function, a state of cholestatic liver/biliary fibrosis, and disrupted lipid and steroid metabolism. Circulating bile acid levels were elevated, which is an indication of liver dysfunction, and plasma cholesterol levels were reduced; however, hepatic bile acid and cholesterol levels were unaltered. Interactome analyses identified apolipoprotein E, hepatocyte nuclear factor 4 alpha, and peroxisome proliferator-activated receptor alpha as key regulatory molecules involved in the effects of TDCPP. Our results demonstrate a targeted effect of TDCPP toxicity on lipid metabolism, including cholesterol, that helps explain the aforementioned phenotypic effects, as chicken embryos are highly dependent on yolk lipids for growth and maintenance throughout development. Finally, our results are in concordance with the literature that describes TDCPP as a cancer-causing agent, since the majority of dysregulated genes were involved in cancer pathways. - Highlights: • TDCPP dysregulates genes involved in immune function and lipid metabolism. • A targeted effect of TDCPP toxicity on cholesterol metabolism is apparent. • A state of cholestatic liver fibrosis is suggested by the expression profile. • Elevated plasma bile acids suggest that TDCPP causes liver dysfunction.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Tumor exosomes induce tunneling nanotubes in lipid raft-enriched regions of human mesothelioma cells

Tunneling nanotubes (TnTs) are long, non-adherent, actin-based cellular extensions that act as conduits for transport of cellular cargo between connected cells. The mechanisms of nanotube formation and the effects of the tumor microenvironment and cellular signals on TnT formation are unknown. In the present study, we explored exosomes as potential mediators of TnT formation in mesothelioma and the potential relationship of lipid rafts to TnT formation. Mesothelioma cells co-cultured with exogenous mesothelioma-derived exosomes formed more TnTs than cells cultured without exosomes within 24–48 h; and this effect was most prominent in media conditions (low-serum, hyperglycemic medium) that support TnT formation (1.3–1.9-fold difference). Fluorescence and electron microscopy confirmed the purity of isolated exosomes and revealed that they localized predominantly at the base of and within TnTs, in addition to the extracellular environment. Time-lapse microscopic imaging demonstrated uptake of tumor exosomes by TnTs, which facilitated intercellular transfer of these exosomes between connected cells. Mesothelioma cells connected via TnTs were also significantly enriched for lipid rafts at nearly a 2-fold higher number compared with cells not connected by TnTs. Our findings provide supportive evidence of exosomes as potential chemotactic stimuli for TnT formation, and also lipid raft formation as a potential biomarker for TnT-forming cells. - Highlights: • Exosomes derived from malignant cells can stimulate an increased rate in the formation of tunneling nanotubes. • Tunneling nanotubes can serve as conduits for intercellular transfer of these exosomes. • Most notably, exosomes derived from benign mesothelial cells had no effect on nanotube formation. • Cells forming nanotubes were enriched in lipid rafts at a greater number compared with cells not forming nanotubes. • Our findings suggest causal and potentially synergistic association of exosomes and tunneling nanotubes in cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Lipid rafts are required for signal transduction by angiotensin II receptor type 1 in neonatal glomerular mesangial cells

Angiotensin II (ANG-II) receptors (AGTRs) contribute to renal physiology and pathophysiology, but the underlying mechanisms that regulate AGTR function in glomerular mesangium are poorly understood. Here, we show that AGTR1 is the functional AGTR subtype expressed in neonatal pig glomerular mesangial cells (GMCs). Cyclodextrin (CDX)-mediated cholesterol depletion attenuated cell surface AGTR1 protein expression and ANG-II-induced intracellular Ca{sup 2+} ([Ca{sup 2+}]{sub i}) elevation in the cells. The COOH-terminus of porcine AGTR1 contains a caveolin (CAV)-binding motif. However, neonatal GMCs express CAV-1, but not CAV-2 and CAV-3. Colocalization and in situ proximity ligation assay detected an association between endogenous AGTR1 and CAV-1 in the cells. A synthetic peptide corresponding to the CAV-1 scaffolding domain (CSD) sequence also reduced ANG-II-induced [Ca{sup 2+}]{sub i} elevation in the cells. Real-time imaging of cell growth revealed that ANG-II stimulates neonatal GMC proliferation. ANG-II-induced GMC growth was attenuated by EMD 66684, an AGTR1 antagonist; BAPTA, a [Ca{sup 2+}]{sub i} chelator; KN-93, a Ca{sup 2+}/calmodulin-dependent protein kinase II inhibitor; CDX; and a CSD peptide, but not PD 123319, a selective AGTR2 antagonist. Collectively, our data demonstrate [Ca{sup 2+}]{sub i}-dependent proliferative effect of ANG-II and highlight a critical role for lipid raft microdomains in AGTR1-mediated signal transduction in neonatal GMCs. - Highlights: • AGTR1 is the functional AGTR subtype expressed in neonatal mesangial cells. • Endogenous AGTR1 associates with CAV-1 in neonatal mesangial cells. • Lipid raft disruption attenuates cell surface AGTR1 protein expression. • Lipid raft disruption reduces ANG-II-induced [Ca{sup 2+}]{sub i} elevation in neonatal mesangial cells. • Lipid raft disruption inhibits ANG-II-induced neonatal mesangial cell growth.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Lipid accumulation-induced hepatocyte senescence regulates the activation of hepatic stellate cells through the Nrf2-antioxidant response element pathway

Highlights: • Oxidative stress caused by lipid deposition causes hepatocyte senescence. • Free fatty acid-induced senescent hepatocytes promote hepatic stellate cell activation and development of hepatic fibrosis. • Senescent hepatocytes regulate hepatic fibrosis through the Nrf2-antioxidant response element pathway. Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease globally. Elderly individuals are at a higher risk of developing NAFLD with severe clinical outcomes. Although NAFLD is closely related to liver aging, the role of hepatocyte senescence in the progression of NAFLD, especially in the development of fibrosis, is still unclear. The early stage of NAFLD is mainly characterized by lipid accumulation in hepatocytes, which could lead to severe oxidative stress, causing cellular senescence. In the present study, hepatocytes cultured in the presence of free fatty acids to induce lipid deposition were used as a hepatocyte senescence model in vitro. Senescent hepatocytes significantly increased the activation of co-cultured primary hepatic stellate cells (HSCs) and the expression of pro-fibrosis molecules. Moreover, the antioxidant regulator nuclear factor erythroid 2-related factor 2 (Nrf2) that was upregulated in senescent hepatocytes was found to be related to the activation of co-cultured HSCs. The Nrf2 agonist sulforaphane, which upregulated the transcriptional activity of the Nrf2-antioxidant response element (ARE) pathway, remarkably inhibited hepatocyte senescence and its activation effect on HSCs. However, the liver tissue obtained from non-alcoholic steatohepatitis (NASH) mice with Nrf2 knockdown showed decreased antioxidation and significant liver senescence and fibrosis. In conclusion, this study confirmed that lipid accumulation induces hepatocyte senescence, which leads to HSC activation and development of hepatic fibrosis. Increasing the activity of the Nrf2-ARE antioxidant pathway in senescent hepatocytes elicited the opposite effect, suggesting that targeting Nrf2 may prevent or delay the progression of aging-related liver fibrosis in NASH.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Recombination between 13 C and 2 H to Form Acetylide ( 13 C 2 2 H – ) Probes Nanoscale Interactions in Lipid Bilayers via Dynamic Secondary Ion Mass Spectrometry: Cholesterol and GM 1 Clustering

Although it is thought that there is lateral heterogeneity of lipid and protein components within biological membranes, probing this heterogeneity has proven challenging. The difficulty in such experiments is due to both the small length scale over which such heterogeneity can occur, and the significant perturbation resulting from fluorescent or spin labeling on the delicate interactions within bilayers. Atomic recombination during dynamic nanoscale secondary ion imaging mass spectrometry (NanoSIMS) is a non-perturbative method for examining nanoscale bilayer interactions. Atomic recombination is a variation on conventional NanoSIMS imaging, whereby an isotope on one molecule combines with a different isotope on another molecule during the ionization process, forming an isotopically enriched polyatomic ion in a distance-dependent manner. In this work, we show that the recombinant ion, 13 C 2 2 H – , is formed in high yield from 13 C- and 2 H-labeled lipids. The low natural abundance of triply labeled acetylide also makes it an ideal ion to probe GM 1 clusters in model membranes and the effects of cholesterol on lipid–lipid interactions. We find evidence supporting the cholesterol condensation effect as well as the presence of nanoscale GM 1 clusters in model membranes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Binding of Cholera Toxin B-Subunit to a Ganglioside GM1-Functionalized PEG-Tethered Lipid Membrane

We report neutron reflectometry (NR) studies of polyethylene glycol (PEG)-tethered model lipid membranes at the solid–liquid interface and of cholera toxin’s B-subunit (CTxB) binding to tethered membranes containing ganglioside GM1 receptors. First, tethered polymer brushes were formed by grafting silane-functionalized PEG lipopolymers to quartz from solution. Subsequent deposition of lipids by Langmuir–Blodgett/Langmuir–Schaefer (LB/LS) resulted in a tethered bilayer structure separated from the solid support by a hydrated PEG layer. NR revealed that the tethers formed a highly hydrated polymer brush, uniformly separating the bilayer from the underlying solid substrate. Further, the lipid bilayer did not significantly perturb the brush’s conformation relative to a free brush. Biological functionality of the tethered bilayers was verified by interacting CTxB, with ganglioside GM1 receptors incorporated into the bilayer. The surface coverage of CTxB bound to the lipid membrane, θ CTB = 0.58 ± 0.08, was consistent with the coverage predicted for random sequential absorption, and toxin binding did not impact the membrane conformation.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Multicomponent and Multiphase Lipid Nanotubes Formed by Gliding Microtubule-Kinesin Motility and Phase-Separated Giant Unilamellar Vesicles

Cytoskeletal filaments and motor proteins are critical components in the transport and reorganization of membrane-based organelles in eukaryotic cells. Previous studies have recapitulated the microtubule-kinesin transport system in vitro to dynamically assemble large-scale nanotube networks from multilamellar liposomes and polymersomes. Moving toward more biologically relevant systems, this work examines whether lipid nanotube (LNT) networks can be generated from giant unilamellar vesicles (GUVs) and subsequently characterizes how the lipid composition may be tuned to alter the dynamics, structure, and fluidity of networks. Here, we describe a two-step process in which microtubule motility (i) drives the transport and aggregation of GUVs to form structures with a decreased energy barrier for LNT formation and (ii) extrudes LNTs without destroying parent GUVs, allowing for the formation of large LNT networks. We further show that the lipid composition of the GUV influences formation and morphology of the extruded LNTs and associated networks. For example, LNTs formed from phase-separated GUVs (e.g., liquid–solid phase-separated and coexisting liquid-ordered and liquid-disordered phase-separated) display morphologies related to the specific phase behavior reflective of the parent GUVs. Overall, the ability to form nanotubes from compositionally complex vesicles opens the door to generating lipid networks that more closely mimic the structure and function of those found in cellular systems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Mesoporous Silica Nanoparticle-Supported Lipid Bilayers (Protocells) for Active Targeting and Delivery to Individual Leukemia Cells

Many nanocarrier cancer therapeutics currently under development, as well as those used in the clinical setting, rely upon the enhanced permeability and retention (EPR) effect to passively accumulate in the tumor microenvironment and kill cancer cells. In leukemia, where leukemogenic stem cells and their progeny circulate within the peripheral blood or bone marrow, the EPR effect may not be operative. Thus, for leukemia therapeutics, it is essential to target and bind individual circulating cells. Here in this research, we investigate mesoporous silica nanoparticle (MSN)-supported lipid bilayers (protocells), an emerging class of nanocarriers, and establish the synthesis conditions and lipid bilayer composition needed to achieve highly monodisperse protocells that remain stable in complex media as assessed in vitro by dynamic light scattering and cryo-electron microscopy and ex ovo by direct imaging within a chick chorioallantoic membrane (CAM) model. We show that for vesicle fusion conditions where the lipid surface area exceeds the external surface area of the MSN and the ionic strength exceeds 20 mM, we form monosized protocells (polydispersity index <0.1) on MSN cores with varying size, shape, and pore size, whose conformal zwitterionic supported lipid bilayer confers excellent stability as judged by circulation in the CAM and minimal opsonization in vivo in a mouse model. Having established protocell formulations that are stable colloids, we further modified them with anti-EGFR antibodies as targeting agents and reverified their monodispersity and stability. Then, using intravital imaging in the CAM, we directly observed in real time the progression of selective targeting of individual leukemia cells (using the established REH leukemia cell line transduced with EGFR) and delivery of a model cargo. In conclusion, overall we have established the effectiveness of the protocell platform for individual cell targeting and delivery needed for leukemia and other disseminated disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Negatively Charged Lipids Exhibit Negligible Effects on the Water Repellency of Montmorillonite Films

Amphiphilic molecules can alter the wettability of soil minerals. To determine how the headgroup chemistry of amphiphiles determines these effects, we investigate a system of the clay montmorillonite with long-chain phospholipids. We use phosphatidylglycerol (PG) phospholipids to contrast with our previous work using phosphatidylethanolamine lipids (PE). Zwitterionic PE lipids can sorb to the negatively-charged montmorillonite surface, whereas negatively-charged PG lipids cannot. Employing a suite of techniques from molecular dynamics, atomic force microscopy, fluorescence microscopy, and contact angle measurements, we define sample characteristics from molecular scale structure to the macroscopic wettability. We find that PG lipids do not significantly alter montmorillonite wetting characteristics, such as the contact angle, flow viscosity, and the characteristic timescale for droplet imbibition. In comparing PE and PG lipid/clay films, we find that, among the phospholipids compared, they must have three characteristics in order to change clay/lipid film wettability: they must bind to the mineral surface, be solid at room temperature, and have a relatively continuous distribution throughout the film.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Conversion of High-Solids Hydrothermally Pretreated Bioenergy Sorghum to Lipids and Ethanol Using Yeast Cultures

Glucose and xylose are the major sugars in cellulosic hydrolysates. The cellulosic sugars can be used for the production of biofuels and value-added bioproducts. In this study, lipid and ethanol were produced from bioenergy sorghum syrups using engineered yeasts. Here, bioenergy sorghum was hydrothermally pretreated at 50% solids loading in a continuous reactor system and mechanically refined sequentially using a burr mill to improve biomass accessibility for hydrolysis. Fed-batch enzymatic hydrolysis was conducted with 50% w/v solids loading to achieve 230 g/L sugar concentration. Different strains of Rhodosporidium toruloides were used to ferment sugars into lipids, and the highest lipid yield of 9.2 g/L was observed. The lipid yield was improved to 19.0 g/l by implementing a two-stage culture where once the sugars were exhausted in the first stage, the yeast was introduced into fresh hydrolysate without adding nitrogen. For ethanol production, the engineered Saccharomyces cerevisiae SR8ΔADH6 was utilized to coferment glucose and xylose. Additionally, the effects of nutrient media (YP, YNB/urea, and urea), cellulosic sugar concentration, and sulfite addition were investigated to optimize the ethanol yield from sorghum syrups. The optimal ethanol yield at 73.3% was obtained from the YNB/urea culture consisting of 34 g glucose/L and 17 g xylose/L.

09 BIOMASS FUELS↗