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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Next-generation poly-L-histidine formulations for miRNA mimic delivery

Many diseases, especially cancer, are caused by the abnormal expression of non-coding microRNAs (miRNAs), which regulate gene expression, leading to the development of miRNA-based therapeutics. Synthetic miRNA inhibitors have shown promising efficacy in blocking the activity of aberrant miRNAs that are upregulated in disease-specific pathologies. On the other hand, miRNAs that aid in preventing certain diseases and are reduced in expression in the disease state need different strategies. To tackle this, miRNA mimics, which mimic the activity of endogenous miRNAs, can be delivered for those miRNAs downregulated in different disease states. However, the delivery of miRNA mimics remains a challenge. Here, we report a cationic polylactic-co-glycolic acid (PLGA)-poly-L-histidine delivery system to deliver miRNA mimics. We chose miR-34a mimics as a proof of concept for miRNA delivery. miR-34a-loaded PLGA-poly-L-histidine nanoparticles (NPs) were formulated and biophysically characterized to analyze the structural properties of miRNA mimic-loaded NPs. In vitro efficacy was determined by investigating miR-34a and downstream target levels and performing cell viability and apoptosis assays. We confirmed in vivo efficacy through prolonged survival of miR-34a NP-treated A549-derived xenograft mice treated intratumorally. The results of these studies establish PLGA-poly-L-histidine NPs as an effective delivery system for miRNA mimics for treating diseases characterized by downregulated miRNAs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

EP300/CBP is crucial for cAMP-PKA pathway to alleviate podocyte dedifferentiation via targeting Notch3 signaling

Podocyte injury is the hallmark of proteinuric glomerular diseases. Notch3 is neo-activated simultaneously in damaged podocytes and podocyte's progenitor cells of FSGS, indicating a unique role of Notch3. We previously showed that activation of cAMP-PKA pathway alleviated podocyte injury possibly via inhibiting Notch3 expression. However, the mechanisms are unknown. In the present study, Notch3 signaling was significantly activated in ADR-induced podocytes in vitro and in PAN nephrosis rats and patients with idiopathic FSGS in vivo, concomitantly with podocyte dedifferentiation. In cultured podocytes, pCPT-cAMP, a selective cAMP-PKA activator, dramatically blocked ADR-induced activation of Notch3 signaling as well as inhibition of cAMP-PKA pathway, thus alleviating the decreased cell viability and podocyte dedifferentiation. Bioinformatics analysis revealed EP300/CBP, a transcriptional co-activator, as a central hub for the crosstalk between these two signaling pathways. Additionally, CREB/KLF15 in cAMP-PKA pathway competed with RBP-J the major transcriptional factor of Notch3 signaling for binding to EP300/CBP. EP300/CBP siRNA significantly inhibited these two signaling transduction pathways and disrupted the interactions between the above major transcriptional factors. These data indicate a crucial role of EP300/CBP in regulating the crosstalk between cAMP-PKA pathway and Notch3 signaling and modulating the phenotypic change of podocytes, and enrich the reno-protective mechanisms of cAMP-PKA pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

LINC00992 exerts oncogenic activities in prostate cancer via regulation of SOX4

Highlights: • LNC992 is significantly overexpressed in PCa and is associated with poor prognosis. • LNC992 is associated with the malignant biological behavior of PCa cells. • LNC992 can positively regulate the expression of SOX4. • LNC992 binds to EIF4A3. • SOX4 abrogates the repressive effects of sh-LNC992 on the PCa cell viability. The critical role of long non-coding RNAs (lncRNAs) has been implicated in prostate cancer (PCa). As one of them, LINC00992 (LNC992) has been revealed by bioinformatics prediction to be significantly overexpressed in PCa. However, the underlying mechanism of LNC992 in PCa has not been well investigated.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

FAK-targeting PROTAC demonstrates enhanced antitumor activity against KRAS mutant non-small cell lung cancer

Focal adhesion kinase (FAK) has been established as a promising therapeutic target for KRAS mutant non-small cell lung cancer (NSCLC). However, phase II clinical trials of a FAK inhibitor (Defactinib) have only shown modest antitumor activity. To address this challenge, here we report the use of a FAK-targeting proteolysis targeting chimera (D-PROTAC) to treat KRAS mutant NSCLC. We validated that D-PROTAC could efficiently eliminate FAK protein via the ubiquitin-proteasome pathway in KRAS mutant NSCLC A427 cells, causing over 90% degradation at 800 nM. After comparing both in vitro and in vivo therapeutic efficacies, we demonstrated that D-PRTOAC outperformed Defactinib in inhibiting tumor growth. Specifically, D-PROTAC at 800 nM reduced cell viability, migration, and invasion by ∼80%. Furthermore, a ∼85% suppression of tumor growth was elicited by D-PROTAC when intratumorally administrated at 10 mg/kg in subcutaneous A427-bearing mice. These results thus demonstrate for the first time that PROTACs may serve as promising therapeutic agents for the intractable NSCLC harboring KRAS mutations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Room-Temperature Calcium Plating and Stripping Using a Perfluoroalkoxyaluminate Anion Electrolyte

Multivalent ion chemistries, like Ca 2+ , used in energy storage boast the potential to utilize solid metallic anodes and provide high volumetric energy density. The promise of such systems relies on the ability to incorporate high-voltage cathode materials while sustaining robust plating and stripping at the anode. These processes are dependent on an electrochemically stable electrolyte for ion transport and storage. In this work, we report an addition to the limited pool of nonaqueous electrolytes capable of plating and stripping calcium at room temperature. The synthesis and structural properties of calcium tetrakis(perfluoro-tert-butoxy) aluminate (Ca[TPFA] 2 ) are described along with the electrochemical performance during plating and stripping (up to 55% Coulombic efficiency) and a proof of concept for full cell viability with a CuS cathode material. X-ray experiments were used to study both the bulk solvation structure around calcium and possible decomposition pathways of the weakly coordinating TPFA anion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Peptoid-Based Nanosheets Exhibiting Broad Antiviral Activity Against Enveloped RNA Viruses

Enveloped RNA viruses, such as Influenza A (H1N1) and Sindbis virus, pose persistent global health threats due to their high mutation rates, efficient transmission, and frequent drug resistance. By mimicking host cell membrane receptors, multivalent virus inhibitors can block viral attachment, making them promising broad-spectrum antiviral agents. However, most of existing antivirals are often limited by strain specificity, short-lived efficacy, and toxicity. Here, we introduce a broad-spectrum antiviral platform based on highly tunable and biocompatible two-dimensional nanomembranes (2DNMs) self-assembled from amphiphilic peptoids, operating via a non-genomic, mutation-insensitive mechanism. By varying peptoid sequence, we design and synthesize over twenty different 2DNMs with various surface charge and high density of viral-attachment ligands (VALs). The self-assembled architecture of these stable 2DNMs provides cooperative noncovalent multivalent binding to virus particles that result in effective inhibition of viral infection. Screening of variants identified three leads that potently suppressed Influenza A (H1N1) and Sindbis virus infection across median tissue culture infectious dose (TCID50), plaque, RT–qPCR, and immunofluorescence assays, while maintaining >90% cell viability. These nanosheets significantly reduced infectious titers, viral RNA replication, and intracellular viral protein expression, indicating inhibition at early stages of viral entry and propagation. The sequence programmability, chemical robustness, and mutation-insensitive antiviral activity distinguish 2DNMs from traditional antivirals and positions them as a versatile materials platform for antiviral coatings, protective barriers, and prophylactic biomedical applications.

Influenza A virus↗
DOE OSTI2022

Supramolecular Copolymers of Peptides and Lipidated Peptides and Their Therapeutic Potential

Supramolecular peptide chemistry offers a versatile strategy to create chemical systems useful as new biomaterials with potential to deliver nearly 1000 known candidate peptide therapeutics or integrate other types of bioactivity. Here, we report on the co-assembly of lipidated β-sheet-forming peptides with soluble short peptides, yielding supramolecular copolymers with various degrees of internal order. At low peptide concentrations, the co-monomer is protected by lodging within internal aqueous compartments and stabilizing internal β-sheets formed by the lipidated peptides. At higher concentrations, the peptide copolymerizes with the lipidated peptide and disrupts the β-sheet secondary structure. The thermodynamic metastability of the co-assembly in turn leads to the spontaneous release of peptide monomers and thus serves as a potential mechanism for drug delivery. We demonstrated the function of these supramolecular systems using a drug candidate for Alzheimer’s disease and found that the copolymers enhance neuronal cell viability when the soluble peptide is released from the assemblies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Structural basis for DNA proofreading

DNA polymerase (DNAP) can correct errors in DNA during replication by proofreading, a process critical for cell viability. However, the mechanism by which an erroneously incorporated base translocates from the polymerase to the exonuclease site and the corrected DNA terminus returns has remained elusive. Here, we present an ensemble of nine high-resolution structures representing human mitochondrial DNA polymerase Gamma, Polγ, captured during consecutive proofreading steps. The structures reveal key events, including mismatched base recognition, its dissociation from the polymerase site, forward translocation of DNAP, alterations in DNA trajectory, repositioning and refolding of elements for primer separation, DNAP backtracking, and displacement of the mismatched base into the exonuclease site. Altogether, our findings suggest a conserved ‘bolt-action’ mechanism of proofreading based on iterative cycles of DNAP translocation without dissociation from the DNA, facilitating primer transfer between catalytic sites. Functional assays and mutagenesis corroborate this mechanism, connecting pathogenic mutations to crucial structural elements in proofreading steps.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Structure and mechanism of biosynthesis of Streptococcus mutans cell wall polysaccharide

Streptococcus mutans, the causative agent of human dental caries, expresses a cell wall attached Serotype c-specific Carbohydrate (SCC) that is critical for cell viability. SCC consists of a polyrhamnose backbone of →3)α-Rha(1 → 2)α-Rha(1→ repeats with glucose (Glc) side-chains and glycerol phosphate (GroP) decorations. This study reveals that SCC has one predominant and two more minor Glc modifications. The predominant Glc modification, α-Glc, attached to position 2 of 3-rhamnose, is installed by SccN and SccM glycosyltransferases and is the site of the GroP addition. The minor Glc modifications are β-Glc linked to position 4 of 3-rhamnose installed by SccP and SccQ glycosyltransferases, and α-Glc attached to position 4 of 2-rhamnose installed by SccN working in tandem with an unknown enzyme. Both the major and the minor β-Glc modifications control bacterial morphology, but only the GroP and major Glc modifications are critical for biofilm formation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Spatially co-registered wide-field nonlinear optical imaging of living and complex biosystems in a total internal reflection geometry

Nonlinear optical microscopy that leverages an objective based total internal reflection (TIR) excitation scheme is an attractive means for rapid, wide-field imaging with enhanced surface sensitivity. Through select combinations of distinct modalities, one can, in principle, access complementary chemical and structural information for various chemical species near interfaces. Here, we report a successful implementation of such a wide-field nonlinear optical microscope system, which combines coherent anti-Stokes Raman scattering (CARS), two-photon fluorescence (TPF), second harmonic generation (SHG), and sum frequency generation (SFG) modalities on the same platform. The intense optical fields needed to drive these high order nonlinear optical processes are achieved through the use of femtosecond pulsed light in combination with the intrinsic field confinement induced by TIR over a large field of view. The performance of our multimodal microscope was first assessed through the experimental determination of its chemical fidelity, intensity and polarization dependences, and spatial resolution using a set of well-defined model systems. Subsequently, its unique capabilities were validated through imaging complex biological systems, including Hydrangea quercifolia pollen grains and Pantoea sp. YR343 bacterial cells. Specifically, the spatial distribution of different molecular groups in the former was visualized via vibrational contrast mechanisms of CARS, whereas co-registered TPF imaging allowed the identification of spatially localized intrinsic fluorophores. We further demonstrate the feasibility of our microscope for wide-field CARS imaging on live cells through independent characterization of cell viability using spatially co-registered TPF imaging. Overall, this approach to TIR enabled wide-field imaging is expected to provide new insights into bacterial strains and their interactions with other species in the rhizosphere in a time-resolved and chemically selective manner.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Computational analysis of metal–metal bonded dimetal tetrabenzoate redox potentials in the context of ammonia oxidation electrocatalysis

Metal–metal bonded complexes are promising candidates for catalyzing redox transformations. Of particular interest is the oxidation of ammonia to dinitrogen, an important half reaction for the potential utilization of ammonia as a fuel or hydrogen carrier. This work computationally explores 30 different metal–metal bonded dimers (5 different metal centers and 6 different benzoate ligand derivatives) to explore the tunability of the redox potential when ammonia is bound to the complexes as an axial ligand, modeling the first step in ammonia oxidation electrocatalysis. We calculate the redox potentials of these compounds, making reference to experimental data when appropriate, identifying two degrees of tunability: a coarse adjustment, changing the metal center, allows for a wide range of redox potentials to be accessed (from +1.0 to –2.0 V vs. ferrocene/ferrocenium in acetonitrile solution) and a fine adjustment, the para-substituent of the benzoate derivative, which affects the redox potential in a smaller range based on the electron donating/withdrawing effects of the substituent. Ruthenium and osmium tetrabenzoate catalysts are prime candidates for next generation ammonia oxidation catalysts because their redox potentials fall within the direct ammonia fuel cell “viability zone” bracketed by the thermodynamic potentials of oxygen reduction (ORR) and nitrogen reduction (NRR). Rhodium tetrabenzoate species fall above the ORR potential, suggesting ammonia oxidation promoted by Rh 2 catalysts could instead be used to facilitate hydrogen production through coupling to hydrogen evolution at a cathode. The redox potentials of rhenium and iridium tetrabenzoate catalysts fall below the NRR potential suggesting that these compounds could be further investigated in the context of electrochemical ammonia synthesis. Each redox event studied involves electron transfer from the M–M δ* orbital regardless of choice of metal or benzoate ligand derivative; this leads us to believe that the chemical reactivity of the various studied compounds will be similar in the context of ammonia oxidation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Engineering peroxisomal biosynthetic pathways for maximization of triterpene production in Yarrowia lipolytica

Constructing efficient cell factories for product synthesis is frequently hampered by competing pathways and/or insufficient precursor supply. This is particularly evident in the case of triterpenoid biosynthesis in Yarrowia lipolytica, where squalene biosynthesis is tightly coupled to cytosolic biosynthesis of sterols essential for cell viability. Here, we addressed this problem by reconstructing the complete squalene biosynthetic pathway, starting from acetyl-CoA, in the peroxisome, thus harnessing peroxisomal acetyl-CoA pool and sequestering squalene synthesis in this organelle from competing cytosolic reactions. This strategy led to increasing the squalene levels by 1,300-fold relatively to native cytosolic synthesis. Subsequent enhancement of the peroxisomal acetyl-CoA supply by two independent approaches, 1) converting cellular lipid pool to peroxisomal acetyl-CoA and 2) establishing an orthogonal acetyl-CoA shortcut from CO 2 -derived acetate in the peroxisome, further significantly improved local squalene accumulation. Using these approaches, we constructed squalene-producing strains capable of yielding 32.8 g/L from glucose, and 31.6 g/L from acetate by employing a cofeeding strategy, in bioreactor fermentations. Our findings provide a feasible strategy for protecting intermediate metabolites that can be claimed by multiple reactions by engineering peroxisomes in Y. lipolytica as microfactories for the production of such intermediates and in particular acetyl-CoA-derived metabolites.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Pot1 promotes telomere DNA replication via the Stn1-Ten1 complex in fission yeast

Abstract Telomeres are nucleoprotein complexes that protect the chromosome-ends from eliciting DNA repair while ensuring their complete duplication. Pot1 is a subunit of telomere capping complex that binds to the G-rich overhang and inhibits the activation of DNA damage checkpoints. In this study, we explore new functions of fission yeast Pot1 by using a pot1-1 temperature sensitive mutant. We show that pot1 inactivation impairs telomere DNA replication resulting in the accumulation of ssDNA leading to the complete loss of telomeric DNA. Recruitment of Stn1 to telomeres, an auxiliary factor of DNA lagging strand synthesis, is reduced in pot1-1 mutants and overexpression of Stn1 rescues loss of telomeres and cell viability at restrictive temperature. We propose that Pot1 plays a crucial function in telomere DNA replication by recruiting Stn1-Ten1 and Polα-primase complex to telomeres via Tpz1, thus promoting lagging-strand DNA synthesis at stalled replication forks.

Carvalho Borges, Pâmela C. (ORCID:0000000244919874↗
DOE OSTI2022

Protective Effect of Phloretin against Hydrogen Peroxide-Induced Oxidative Damage by Enhancing Autophagic Flux in DF-1 Cells

Phloretin (PHL) is a dihydrochalcone flavonoid isolated from the peel and root bark of apples, strawberries, and other plants with antioxidative characteristic. In this study, we aimed to investigate the protective effect and the potential mechanism of PHL on hydrogen peroxide (H2O2)-induced oxidative damage in DF-1 cells. The results showed that PHL exhibited no cytotoxic effect on DF-1 cells at concentration below 20 μM. PHL markedly increased H2O2-reduced cell viability, decreased H2O2-induced apoptosis, as evidenced by reduced apoptosis rate, the upregulation of gene and protein level of Bcl-2, and the downregulation of gene and protein level of Bax and Cleaved caspase3. In addition, PHL reduced H2O2-induced reactive oxygen species (ROS) production and restored antioxidant enzymes activities as well as mitochondrial membrane potential in a dose-dependent manner. Moreover, PHL prior to H2O2 further increased LC3-II level, promoted p62 turnover and improved lysosomal function. Importantly, autophagy inhibitor chloroquine (CQ) reversed the protective effect of PHL, and increased H2O2-induced apoptosis. Furthermore, PHL inhibited the phosphorylation levels of ERK, p38, and JNK. Collectively, these results indicate that PHL could attenuate H2O2-induced oxidative injury and apoptosis by maintaining lysosomal function and promoting autophagic flux, and MAPKs pathway may be involved in this process. Our study provides evidence that PHL could as a new strategy to against oxidative damage in poultry industry.

Song, Dan↗
DOE OSTI2021

Improving tolerance of yeast to lignocellulosic-derived feedstocks and products

Combined substrate-product toxicity remains one of the main obstacles hampering the scale-up and cost-effectiveness of bioprocesses harnessing lignocellulosic feedstocks, the most abundant, renewable terrestrial resource. Hydrolytic pretreatments release numerous inhibitors impinging on cell viability: the three most acute to yeast S. cerevisiae (the industry dominant biocatalyst) — and universal to all plant sources — are furfural, hydroxymethylfurfural (HMF), and acetic acid. Likewise, desired fermentation products, such as fuel ethanol or commodity organic acids, are toxic to microbes, typically via unknown biological mechanisms. Here, we have engineered both hydrolysate and end-product tolerance in yeast by combining previously-shown alcohol protective modifications with evolved genetic activities targeting the major pretreatment inhibitors. When tested on a wide sampling of genuine lignocellulosic feedstocks, ethanol production increased by >30% on average to titers >100 g/L, achieving parity with clean-sugar equivalents where conditions permit. Furthermore, we designed the tolerance capability to be fully transferable to pre-existing metabolic chassis strains. As such, we “drop-in” hydrolysate competence into one producing lactic acid, demonstrating the first-ever production of a cellulosic plastic at industrial titers. Our advances thus renew the potential of cellulosic biomass utilization for sustainable fuel and non-fuel products at scale.

09 BIOMASS FUELS↗
DOE OSTI2020

Enhanced Corneal Penetration of a Poorly Permeable Drug Using Bioadhesive Multiple Microemulsion Technology

Corneal penetration is a key rate limiting step in the bioavailability of topical ophthalmic formulations that incorporate poorly permeable drugs. Recent advances have greatly aided the ocular delivery of such drugs using colloidal drug delivery systems. Ribavirin, a poorly permeable BCS class-III drug, was incorporated in bioadhesive multiple W/O/W microemulsion (ME) to improve its corneal permeability. The drug-loaded ME was evaluated regarding its physical stability, droplet size, PDI, zeta potential, ultrastructure, viscosity, bioadhesion, in vitro release, transcorneal permeability, cytotoxicity, safety and ocular tolerance. Our ME possessed excellent physical stability, as it successfully passed several cycles of centrifugation and freeze–thaw tests. The formulation has a transparent appearance due to its tiny droplet size (10 nm). TEM confirmed ME droplet size and revealed its multilayered structure. In spite of the high aqueous solubility and the low permeability of ribavirin, this unique formulation was capable of sustaining its release for up to 24 h and improving its corneal permeability by 3-fold. The in vitro safety of our ME was proved by its high percentage cell viability, while its in vivo safety was confirmed by the absence of any sign of toxicity or irritation after either a single dose or 14 days of daily dosing. Our ME could serve as a vehicle for enhanced ocular delivery of drugs with different physicochemical properties, including those with low permeability.

Ibrahim, Mohamed Moustafa↗
DOE OSTI2022

Effect of Foot-and-Mouth Disease Virus 2B Viroporin on Expression and Extraction of Mammalian Cell Culture Produced Foot-and-Mouth Disease Virus-like Particles

To improve the production of foot-and-mouth disease (FMD) molecular vaccines, we sought to understand the effects of the FMD virus (FMDV) 2B viroporin in an experimental, plasmid-based, virus-like particle (VLP) vaccine. Inclusion of the FMDV viroporin 2B into the human Adenovirus 5 vectored FMD vaccine enhanced transgene expression despite independent 2B expression negatively affecting cell viability. Evaluating both wildtype 2B and mutants with disrupted viroporin activity, we confirmed that viroporin activity is detrimental to overall transgene expression when expressed independently. However, the incorporation of 2B into an FMD molecular vaccine construct containing a wildtype FMDV 3C protease, a viral encoded protease responsible for processing structural proteins, resulted in enhancement of transgene expression, validating previous observations. This benefit to transgene expression was negated when using the FMDV 3CL127P mutant, which has reduced processing of host cellular proteins, a reversion resulting from 2B viroporin activity. Inclusion of 2B into VLP production constructs also adversely impacted antigen extraction, a possible side effect of 2B-dependent rearrangement of cellular membranes. These results demonstrate that inclusion of 2B enhanced transgene expression when a wildtype 3C protease is present but was detrimental to transgene expression with the 3CL127P mutant. This has implications for future molecular FMD vaccine constructs, which may utilize mutant FMDV 3C proteases.

2B↗
DOE OSTI2022

Electrical sensing, tracking, and actuation of droplets

Devices, techniques, and processes are disclosed that use electrical impedance to detect of the presence and contents of droplets including cells, nucleic acids, proteins, or solute concentrations in an array of retrievable, trackable, trapped droplets in a fluidic system. Electrodes may be positioned underneath individual droplet traps in a microchannel to assay droplet contents and/or actuating droplets for the release of the droplets from corresponding traps. The disclosed technology may be used for detection of the results of solvent extraction processes including time-dependent quantification of metal ion concentration in the aqueous and organic phases, for wastewater treatment, heavy metal detection, pharmaceutical industry, and/or biotechnology, or for environmental monitoring of wastewater for toxic metal, monitoring of biological cell viability and proliferation, monitoring of extraction processes used in heavy metal mining, monitoring of extraction processes used in nuclear fuel processing, monitoring kinetics of enzyme processes, and/or assessing pharmacodynamics and drug efficacy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗