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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Synthesis of quantum dots

Common approaches to synthesizing alloyed quantum dots employ high-cost, air-sensitive phosphine complexes as the selenium precursor. Disclosed quantum dot synthesis embodiments avoid these hazardous and air-sensitive selenium precursors. Certain embodiments utilize a combination comprising a thiol and an amine that together reduce and complex the elemental selenium to form a highly reactive selenium precursor at room temperature. The same combination of thiol and amine acts as the reaction solvent, stabilizing ligand, and sulfur source in the synthesis of quantum dot cores. A non-injection approach may also be used. The optical properties of the quantum dots synthesized by this new approach can be finely tuned for a variety of applications by controlling size and/or composition of size and composition. Further, using the same approach, a shell can be grown around a quantum dot core that improves stability, luminescence efficiency, and may reduce toxicity.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Atomic Layer Deposition for Spatial Control of Redox Reaction Selectivity

Photocatalytic water splitting holds great potential in the pursuit of the U.S. Department of Energy's Hydrogen Shot initiative to bring the cost of H2 to $1/kg by 2031. A key challenge in the development of photocatalysts is increasing their overall solar-to-hydrogen efficiency by enhancing charge separation yields and redox selectivity. In this work, we use area selective ALD of oxide films to develop tunable interphase layers for selective oxidation and reduction reactions on a single substrate. This presentation details initial synthesis and characterization of Pt- and Au-based planar thin film electrodes in which Au regions were deactivated towards ALD growth through self-assembled thiol monolayers. The suppression of TiO2 ALD selectivity of thiols was assessed through ellipsometry, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. A patterned planar sample comprised of interdigitated arrays of Au and Pt, used as a surrogate for a photocatalyst particle containing two different co-catalysts, was exposed to ALD growth and removal of the inhibitor species. Scanning electrochemical microscopy (SECM) was used then to probe the local activity of different regions of the patterned surface towards the hydrogen evolution reaction (HER) and iron oxidation and correlated with the ionic and e- blocking effects of the area selective ALD coating. We will also detail the application of these findings to the ongoing development of 3D, particle-based photocatalysts.

atomic layer deposition↗
DOE OSTI2015

A Processable Shape Memory Polymer System for Biomedical Applications

Polyurethane shape memory polymers (SMPs) with tunable thermomechanical properties and advanced processing capabilities are synthesized, characterized, and implemented in the design of a microactuator medical device prototype. The ability to manipulate glass transition temperature ( T g ) and crosslink density in low-molecular weight aliphatic thermoplastic polyurethane SMPs is demonstrated using a synthetic approach that employs UV catalyzed thiol-ene “click” reactions to achieve postpolymerization crosslinking. Polyurethanes containing varying C=C functionalization are synthesized, solution blended with polythiol crosslinking agents and photoinitiator and subjected to UV irradiation, and the effects of number of synthetic parameters on crosslink density are reported. Thermomechanical properties are highly tunable, including glass transitions tailorable between 30 and 105 °C and rubbery moduli tailorable between 0.4 and 20 MPa. This new SMP system exhibits high toughness for many formulations, especially in the case of low crosslink density materials, for which toughness exceeds 90 MJ m –3 at select straining temperatures. To demonstrate the advanced processing capability and synthetic versatility of this new SMP system, a laser-actuated SMP microgripper device for minimally invasive delivery of endovascular devices is fabricated, shown to exhibit an average gripping force of 1.43 ± 0.37 N and successfully deployed in an in vitro experimental setup under simulated physiological conditions.

42 ENGINEERING↗
DOE OSTI2019

Different reactivity to glutathione but similar tumor cell toxicity of chalcones and their quinolinone analogues

Non-enzyme catalyzed nucleophilic addition of reduced glutathione (GSH) onto two open-chain sulfonamide chalcones and two quinolinone-chalcone hybrids were studied to investigate the relationship between tumor cell cytotoxic activities and GSH-reactivities of the compounds. The consumption of the chalcones or the quinolinone-chalcone hybrids due to conjugation with GSH was evaluated by analytical high-performance liquid chromatography, and the formed diastereomeric adducts were identified by liquid chromatography–mass spectrometry. When the reaction was conducted with the open-chain chalcones, the equilibria were shifted towards formation of the respective GSH-conjugates. On the other hand, the cyclic chalcone derivatives with the quinolinone moiety were found to equilibrate to mixtures containing predominantly the reactants despite the strong electron withdrawing group present in the B-ring of the compounds. The observed opposite behavior can be rationalized by reduced thiol-reactivity of the quinolinone-chalcone hybrids and fast decomposition of their GSH-conjugates. A combined X-ray diffraction and theoretical approach were used to explain the observed difference in the reactivities towards GSH. However, structural differences did not influence tumor cell (SF-295, PC-3 and HCT-116) cytotoxicity of the evaluated compounds. Accordingly, the altered GSH-reactivity seems to be not a determining factor in the tested tumor cell cytotoxic activity of the investigated compounds.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Fluorescent Labeling of Protein Using Blue-Emitting 8-Amino-BODIPY Derivatives

8-Amino-BODIPY (boron-dipyrromethane) dyes show bright blue fluorescence. Disclosed here are synthesis and characterization of the photophysical properties of a series of functionalized 8-Amino-BODIPY (BP1–4) for protein labeling. The compact structure and solvent-insensitive absorption property of the dye are desirable features for protein labeling. For the model protein, bovine serum albumin (BSA), the labeling proceeds under mild condition via amide bond formation or thiol-ene conjugation with maintaining the bright blue fluorescence. The chromatography and mass spectroscopy analysis clearly support the labeling of the BODIPY dye on the BSA. The protein labeling with blue-emitting BODIPY would be applicable for studying protein dynamics and fluorescence resonance energy transfer (FRET) with intrinsic biomolecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Octacarbamoylated and octathiocarbamoylated resorcinarenes: transformations and acceptor properties

A series of octa(thio)carbamoylated resorcinarenes was synthesized by the reactions of rccc-resorcinarenes with N,N-dimethylcarbamoyl and N,N-dimethylthiocarbamoyl chlorides in the presence of alkali carbonates. The derivatives with thiocarbamoyl groups were transformed into octa(carbamoylthio)resorcinarenes by the thione—thiol rearrangement. In a homogeneous medium octacarbamoylated resorcinarenes demonstrated high acceptor properties and selectivity to cesium cations but manifested low extraction ability towards alkali metal cations from the aqueous phase to organic one because of the formation of stable films at the interface. Resorcinarenes with thiocarbamoyl and carbamoylthio groups are capable of extracting lanthanides (Nd{sup 3+}, Yb{sup 3+}) from aqueous media and are selective to Nd{sup 3+} cations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Stabilization of dinitrosyl iron complexes under matrix isolation conditions: solvent and polymer effects on the synthesis of composites based on poly(methyl methacrylate) and iron complexes [Fe{sub 2}(μ-NCS-R){sub 2}(NO){sub 4}]

Homogeneous composites based on poly(methyl methacrylate) and its copolymers with methacrylic acid and on the nitrosyl iron complexes with 2-mercaptobenzimidazole and 2-mercaptobenzthiazole were synthesized. An analysis of the experimental data obtained by the methods of small-angle X-ray diffraction and SQUID magnetometry in combination with the results of quantum chemical calculations showed that the nitrosyl complexes did not retain their initial binuclear structure under the matrix isolation conditions: some complexes decompose to mononuclear ones. The percentage ratio of the dimers and monomers depends on the fraction of the methacrylic acid copolymer in the polymeric matrix and is almost independent of the type of thiol ligand in the iron complex.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

S-Methyl diethylthiophosphinate in mono- and di(dechloromethylthioylation) of substituted benzylidene chlorides

The main route of a new reaction of (dichloromethyl)arenes with S-methyl diethylthiophosphinate is the attack of the thiol sulfur atom (P–SMe) on the methylene carbon atom. A new method for synthesizing dimethyl dithioacetals of arenecarbaldehydes without using highly toxic methanethiol was developed. The suggested approach involves di(dechloromethylthioylation) of the dichloromethyl group of (dichloromethyl)arenes with S-methyl diethylthiophosphinate at a reagent ratio of 1: 2.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Biodistribution and stability of CdSe core quantum dots in mouse digestive tract following per os administration: Advantages of double polymer/silica coated nanocrystals

Highlights: Black-Right-Pointing-Pointer New QDs coated with combination of polythiol ligands and silica shell were synthesized. Black-Right-Pointing-Pointer We examine the QDs stability in digestive tract of mice after per os administration. Black-Right-Pointing-Pointer The polymer/silica shell prevents QDs degradation and fluorescence quenching in vivo. -- Abstract: CdSe-core, ZnS-capped semiconductor quantum dots (QDs) are of great potential for biomedical applications. However, applications in the gastrointestinal tract for in vivo imaging and therapeutic purposes are hampered by their sensitivity to acidic environments and potential toxicity. Here we report the use of coatings with a combination of polythiol ligands and silica shell (QDs PolyT-APS) to stabilize QDs fluorescence under acidic conditions. We demonstrated the stability of water-soluble QDs PolyT-APS both in vitro, in strong acidic solutions, and in vivo. The biodistribution, stability and photoluminescence properties of QDs in the gastrointestinal tract of mice after per os administration were assessed. We demonstrated that QDs coated with current traditional materials - mercapto compounds (QDs MPA) and pendant thiol group (QDs PolyT) - are not capable of protecting QDs from chemically induced degradation and surface modification. Polythiol ligands and silica shell quantum dots (QDs PolyT-APS) are suitable for biological and biomedical applications in the gastrointestinal tract.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Transient light-induced intracellular oxidation revealed by redox biosensor

Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

New insights into the posttranslational regulation of human cytosolic thioredoxin by S-palmitoylation

High level of palmitate is associated with metabolic disorders. We recently showed that enhanced level of S-palmitoylated cytosolic thioredoxin (Trx1) in mouse liver was new characteristic feature of insulin resistance. However, our understanding of the effect of S-palmitoylation on Trx1 is limited, and the tissue specificity of Trx1 S-palmitoylation is unclear. Here we show that S-palmitoylation also occurs at Cys73 of Trx1 in living endothelial cells, and the level of S-palmitoylated Trx1 undergoes regulation by insulin signaling. Trx1 prefers thiol-thioester exchange with palmitoyl-CoA to acetyl-CoA. S-palmitoylation alters conformation or secondary structure of Trx1, as well as decreases the ability of Trx1 to transfer electrons from thioredoxin reductase to S-nitrosylated protein–tyrosine phosphatase 1B and S-nitroso-glutathione. Our results demonstrate that S-palmitoylation is an important post-translational modification of human Trx1. - Highlights: • S-palmitoylation occurs at Cys73 of Trx1 in living endothelial cells. • Insulin signaling may regulate level of S-palmitoylated Trx1 in the cells. • S-palmitoylation plays significant effects on Trx1 structure and functions.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Diphenyl diselenide regulates Nrf2/Keap-1 signaling pathway and counteracts hepatic oxidative stress induced by bisphenol A in male mice

Highlights: • BPA exposure induced hepatic oxidative stress in a sex-dependent manner in mice. • BPA exposure deregulates Nrf2/keap1 pathway in the mouse liver. • (PhSe){sub 2} reversed hepatic oxidative stress caused by BPA in male mice. • (PhSe){sub 2} modulates NrF2/keap1 pathway in male mice exposed to BPA. Bisphenol A (BPA) is a chemical toxicant that has deleterious effects on human. BPA causes oxidative stress in tissues, including the liver. Diphenyl diselenide (PhSe){sub 2} improves the antioxidant response via activation of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/Kelch-like ECH-associated protein (keap 1) pathway in macrophage cells. In the present study, we investigated whether (PhSe){sub 2} counteracts hepatic oxidative stress induced by BPA in male and female Swiss mice. Three-week-old mice received by the intragastric (i.g.) route BPA (5 mg/kg) from 21st to 60th postnatal day (PND). At PND 61, the mice were treated with (PhSe){sub 2} (1 mg/kg, i.g.) for seven days. Parameters of hepatic damage and oxidative stress were determined in male and female mice. The results show that BPA increased the activity of aspartate aminotransferase in female mice, and in male mice the activity of alanine aminotranseferase was increased. Male and female mice had an increase in fat mass accumulation. Male mice showed an increase in hepatic oxidative damage of proteins and a decrease in non-enzymatic (ascorbic acid and non-protein thiol) and enzymatic (superoxide dismutase) defenses, which are consistent with oxidative stress status. Male mice were more susceptible than female mice to hepatic oxidative stress induced by BPA. BPA decreased Nrf2/Keap1 protein content in male mice. (PhSe){sub 2} reduced hepatic oxidative stress induced by BPA in male mice. Our results demonstrate that male mice were more susceptible to hepatic oxidative stress induced by BPA than female mice. (PhSe){sub 2} regulated Nrf2/Keap-1 signaling pathway and countered hepatic oxidative stress induced by BPA in male mice.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Structural and biochemical characterization of a recombinant triosephosphate isomerase from Rhipicephalus (Boophilus) microplus

Triosephosphate isomerase (TIM) is an enzyme with a role in glycolysis and gluconeogenesis by catalyzing the interconversion between glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. This enzyme has been used as a target in endoparasite drug development. In this work we cloned, expressed, purified and studied kinetic and structural characteristics of TIM from tick embryos, Rhipicephalus (Boophilus) microplus (BmTIM). The Km and Vmax of the recombinant BmTIM with glyceraldehyde 3-phosphate as substrate, were 0.47 mM and 6031 {micro}mol min{sup -1} mg protein{sup -1}, respectively. The resolution of the diffracted crystal was estimated to be 2.4 {angstrom} and the overall data showed that BmTIM is similar to other reported dimeric TIMs. However, we found that, in comparison to other TIMs, BmTIM has the highest content of cysteine residues (nine cysteine residues per monomer). Only two cysteines could make disulfide bonds in monomers of BmTIM. Furthermore, BmTIM was highly sensitive to the action of the thiol reagents dithionitrobenzoic acid and methyl methane thiosulfonate, suggesting that there are five cysteines exposed in each dimer and that these residues could be employed in the development of species-specific inhibitors.

03 NATURAL GAS↗
DOE OSTI2013

Stability and biocompatibility of photothermal gold nanorods after lyophilization and sterilization

Graphical abstract: - Highlights: • Morphological changes are observed for CTABr capped gold nanorods over time. • Polystyrenesulfonate (PSS) and polyethyleneglycol (PEG) coated nanorods are stable. • Re-suspendible and sterilizable colloids are prepared using those capping agents. • Those materials are efficient heat sinks potentially used in photothermal therapy. - Abstract: Suspensions in phosphate buffered saline (PBS) of gold nanorods stabilized with cetyltrimethyl ammonium chloride (CTABr), polystyrenesulfonate (PSS) and methyl-polyethyleneglycol-thiol (m-PEG-SH) have been prepared and the evolution of their colloidal stability and plasmonic response over time has been evaluated. Their performance after lyophilization, alcoholic sterilization and resuspension has also been characterized. Sub-cytotoxic doses on HeLa cells were calculated for the three surface functionalizations used. Their heating efficiency at different exposure times was also evaluated after being irradiated with near infrared light. The best results were obtained for m-PEG-SH stabilized rods, which were not only stable, sterilizable and lyophilizable, but also biocompatible at all doses tested, showing potential as a stable, re-suspendible and biocompatible hyperthermic agent.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Trivalent chromium removal from aqueous solutions by a sol–gel synthesized silica adsorbent functionalized with sulphonic acid groups

Highlights: • Corpuscular sulphonic acid-functionalized silica holds improved uptake of chromium. • Mesopores on adsorbent facilitate (CH{sub 3}COO){sub 2}Cr{sup +} ion uptake on sulphonate sites. • Formation of chromium acetate sulphonate complex proposed from XPS results. • Fixed bed chromium uptake results suggest potential industrial use. - Abstract: A high capacity hybrid silica adsorbent was synthesized via sol–gel processing with sulphonic acid groups as trivalent chromium complex ions chelators from aqueous solutions. The synthesis included co-condensation of tetraethoxysilane (TEOS) with 3-(mercaptopropyl)trimethoxysilane (MPS), and oxidation of thiol to sulphonic acid groups. Chromium uptake kinetic, batch and fixed-bed experiments were performed to assess the removal of this metal from aqueous solutions. {sup 13}C, {sup 29}Si CPMAS NMR, FTIR, XPS were used to characterize the adsorbent structure and the nature of chromium complexes on the adsorbent surface. Chromium maximum uptake was obtained at pH 3 (72.8 mg/g). Elemental analysis results showed ligand density of 1.48 mmol sulphonic groups/g. About 407 mL of Cr(III) solution (311 mg/L) were treated to breakthrough point reaching ≤0.06 mg/L at the effluent. These results comply with USEPA regulation for chromium concentration in drinking water (≤0.1 mg/L). The adsorbent shows potential to be used in chromium separations to the industrial level.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Integrative Multi-PTM Proteomics Reveals Dynamic Global, Redox, Phosphorylation, and Acetylation Regulation in Cytokine-treated Pancreatic Beta Cells

Studying regulation of protein function at a systems level necessitates an understanding of the interplay among diverse post-translational modifications (PTMs). A variety of proteomics sample processing workflows are currently used to study specific PTMs but rarely characterize multiple types of PTMs from the same sample inputs. Method incompatibilities and laborious sample preparation steps complicate large-scale physiological investigations and can lead to variations in results. The single-pot, solid-phase-enhanced sample preparation (SP3) method for sample cleanup is compatible with different lysis buffers and amenable to automation, making it attractive for high-throughput multi-PTM profiling. Herein, we describe an integrative SP3 workflow for multiplexed quantification of protein abundance, cysteine thiol oxidation, phosphorylation, and acetylation. The broad applicability of this approach is demonstrated using cell and tissue samples, and its utility for studying interacting regulatory networks is highlighted in a time-course experiment of cytokine-treated ß-cells. We observed a swift response in global regulation of protein abundances consistent with rapid activation of JAK-STAT and NF-?B signaling pathways. Regulators of these pathways as well as proteins involved in their target processes displayed multi-PTM dynamics indicative of a complex cellular response stages: acute, adaptation, and chronic (prolonged stress). PARP14, a negative regulator of JAK-STAT, had multiple co-localized PTMs that may be involved in intraprotein regulatory crosstalk. Our workflow provides a high-throughput platform that can profile multi-PTMomes from the same sample set, which is valuable in unraveling the functional roles of PTMs and their co-regulation.

proteomics, PTM, automation, SP3, cysteine thiol o↗
DOE OSTI2012

Curcumin targeting the thioredoxin system elevates oxidative stress in HeLa cells

The thioredoxin system, composed of thioredoxin reductase (TrxR), thioredoxin (Trx), and NADPH, is ubiquitous in all cells and involved in many redox-dependent signaling pathways. Curcumin, a naturally occurring pigment that gives a specific yellow color in curry food, is consumed in normal diet up to 100 mg per day. This molecule has also been used in traditional medicine for the treatment of a variety of diseases. Curcumin has numerous biological functions, and many of these functions are related to induction of oxidative stress. However, how curcumin elicits oxidative stress in cells is unclear. Our previous work has demonstrated the way by which curcumin interacts with recombinant TrxR1 and alters the antioxidant enzyme into a reactive oxygen species (ROS) generator in vitro. Herein we reported that curcumin can target the cytosolic/nuclear thioredoxin system to eventually elevate oxidative stress in HeLa cells. Curcumin-modified TrxR1 dose-dependently and quantitatively transfers electrons from NADPH to oxygen with the production of ROS. Also, curcumin can drastically down-regulate Trx1 protein level as well as its enzyme activity in HeLa cells, which in turn remarkably decreases intracellular free thiols, shifting the intracellular redox balance to a more oxidative state, and subsequently induces DNA oxidative damage. Furthermore, curcumin-pretreated HeLa cells are more sensitive to oxidative stress. Knockdown of TrxR1 sensitizes HeLa cells to curcumin cytotoxicity, highlighting the physiological significance of targeting TrxR1 by curcumin. Taken together, our data disclose a previously unrecognized prooxidant mechanism of curcumin in cells, and provide a deep insight in understanding how curcumin works in vivo. -- Highlights: ► Curcumin induces oxidative stress by targeting the thioredoxin system. ► Curcumin-modified TrxR quantitatively oxidizes NADPH to generate ROS. ► Knockdown of TrxR1 augments curcumin's cytotoxicity in HeLa cells. ► Curcumin sensitizes HeLa cells to oxidative stress.

60 APPLIED LIFE SCIENCES↗