Formulations of hydroxypyridonate actinide/lanthanide decorporation agents
Provided herein are pharmaceutical formularions comprising a 1,2-HOPO chelating agent and/or 3,2-HOPO chelating agent.
Abergel, Rebecca J.↗
SEARCH · Search NASA
Results for “chelation”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Systems and methods for separating radium from lead, bismuth, and thorium
Methods for separating Ra from Pb, Bi, and Th are provided, the methods can include: providing a first mixture comprising Ra, Pb, Bi, and/or Th; providing a system that can include: a first vessel housing a first media; a second vessel in fluid communication with the first vessel, the second vessel housing a second media; and a third vessel in fluid communication with the second vessel, the third vessel housing a third media; and exposing the first mixture to the first media within the first vessel then, through the fluid communication, exposing the first remainder to the second media in the second vessel, then, through fluid communication, exposing the next remainder to the third media in the third vessel, the exposing separating the Th and Bi from the Ra and Pb, and the Ra from the Pb. Methods for separating Ra from being associated with a media are also provided. The methods can include: exposing the Ra and media to a chelating agent to form a mixture comprising the Ra complexed with the chelating agent.
O'Hara, Matthew J.↗
Lead Adsorption and Desorption at the Barite (001) Surface in the Presence of EDTA
Scaling minerals, such as barite, can cause detrimental consequences for oil/gas pipelines and water systems, but their formation can be inhibited by organic chelators such as ethylenediaminetetraacetic acid (EDTA). Here, we resolve how EDTA affects sorption and desorption of Pb at the barite (001) surface using a combination of X-ray scattering and microscopy measurements. In the presence of EDTA, Pb incorporated in the topmost part of the barite surface and adsorbed as inner-sphere complexes on the surface. In barite saturated solutions containing [Pb] ≥ 100 μM, overgrowth films grew along step edges. These films were exclusively monolayer thick, indicating that their growth was a self-limiting process. Approximately half of the Pb was removed after 14.5 h reaction with a Pb-free EDTA solution where most of the desorption occurred to adsorbed Pb rather than incorporated Pb. Dissolution proceeded primarily via step retreat and etch pit formation in EDTA, but in deionized water, the secondary phase was quickly removed within 3 min. Together these results suggest EDTA binds to both the surface and Pb in solution, which limits Pb sorption. However, EDTA binding to the surface also inhibits removal of the secondary phase that formed at higher Pb concentrations.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Novel theranostic agent for PET imaging and targeted radiopharmaceutical therapy of tumour-infiltrating immune cells in glioma
Background: Malignant gliomas are deadly tumours with few therapeutic options. Although immunotherapy may be a promising therapeutic strategy for treating gliomas, a significant barrier is the CD11b + tumour-associated myeloid cells (TAMCs), a heterogeneous glioma infiltrate comprising up to 40% of a glioma's cellular mass that inhibits anti-tumour T-cell function and promotes tumour progression. A theranostic approach uses a single molecule for targeted radiopharmaceutical therapy (TRT) and diagnostic imaging; however, there are few reports of theranostics targeting the tumour microenvironment. Methods: Utilizing a newly developed bifunctional chelator, Lumi804, an anti-CD11b antibody (αCD11b) was readily labelled with either Zr-89 or Lu-177, yielding functional radiolabelled conjugates for PET, SPECT, and TRT. Findings: 89 Zr/ 177 Lu-labeled Lumi804-αCD11b enabled non-invasive imaging of TAMCs in murine gliomas. Additionally, 177 Lu-Lumi804-αCD11b treatment reduced TAMC populations in the spleen and tumour and improved the efficacy of checkpoint immunotherapy. Interpretation: 89 Zr- and 177 Lu-labeled Lumi804-αCD11b may be a promising theranostic pair for monitoring and reducing TAMCs in gliomas to improve immunotherapy responses.
60 APPLIED LIFE SCIENCES↗
Co-assembly of liposomes, Dendrimersomes, and Polymersomes with amphiphilic Janus dendrimers conjugated to Mono- and Tris-Nitrilotriacetic Acid (NTA, TrisNTA) enhances protein recruitment
Metal-chelating ligands such as nitrilotriacetic acid (NTA) bind to polyhistidine-tagged (His-tagged) proteins. Lipids conjugated to NTA are widely used to decorate the surface of liposomes with proteins in cell biology applications. Multivalent NTA ligands such as tris-nitrilotriacetic acid (TrisNTA) display higher affinities than the monovalent NTA when co-assembled with phospholipids and cholesterol in liposomes. However, there is a limited number of available lipids conjugated to NTA and only few are commercially available. Additionally, their activity diminishes during storage or upon exposure to air. Here we report a library of five amphiphilic Janus dendrimers conjugated to NTA (JD-NTA) and three to TrisNTA (JD-TrisNTA). Both JD-NTA and JD-TrisNTA are indefinitely stable at room temperature in air and preliminary results demonstrate that they co-assemble with phospholipids and cholesterol into liposomes, with Janus dendrimers into dendrimersomes, and with block copolymers into polymersomes. The resulting hybrid liposomes co-assembled with JD-NTA display up to thirty-fold higher activity towards His-tagged fluorescent proteins when compared to lipid-NTAs. Hybrid liposomes co-assembled with JD-TrisNTA exhibit even higher binding affinity to His-tagged proteins and can function at much lower ligand concentration in hybrid liposomes than those containing JD-NTA. These preliminary results demonstrate the power of modular synthesis of JD-NTA or JD-TrisNTA to provide highly efficient new tools for biological reconstitution and synthetic cell biology as well as for nanomedicine.
36 MATERIALS SCIENCE↗
Oxidation states of iron and manganese in lignocellulose altered by the brown rot fungus Gloeophyllum trabeum measured in-situ using X-ray absorption near edge spectroscopy (XANES)
Brown rot fungi utilize iron as part of a chelator-mediated Fenton (CMF) reaction during wood biodegradation. Research suggests these fungi reduce Fe 3+ to promote oxygen radical generation resulting in depolymerization of the wood cell wall. High levels of Mn are also found in wood decayed by brown rot fungi. However, little is known about the oxidation states of Fe and Mn during the decay process. X-ray absorption near edge spectroscopy (XANES) can be used to examine metal oxidation states and coordination chemistry. In this work, XANES experiments were conducted on wood decayed by Gloeophyllum trabeum over 2–8 weeks with results showing that Mn 2+ and Fe 3+ predominated for metal oxidation states. However, Fe 2+ was present at sites of greater fungal growth In certain cases, the μXANES measurements showed that the fraction of Fe 2+ in the wood samples was as high as 50%. Localized areas of reduced iron corresponded with areas of greater fungal hyphal mass which is in agreement with how brown rot fungi decay wood via the CMF reaction. The limited change in oxidation state of Mn observed in wood with active fungal activity suggests that the role of manganese in CMF biodegradation chemistry should be further explored.
59 BASIC BIOLOGICAL SCIENCES↗
Heterogeneous response of cancer-associated fibroblasts to the glucose deprivation through mitochondrial calcium uniporter
Highlights: • CAFs from a tumor mass are heterogeneous under the glucose deficient condition. • CAFs survive under glucose deficient condition by activation of TGF-β and calcium. • Calcium influx to mitochondria is critical for survival of glucose-deficient CAFs. • MCU in CAFs could be a feasible target for the development of anticancer drugs. Cancer-associated fibroblasts (CAFs) are an abundant component of the tumor microenvironment and have distinct features from normal fibroblasts (NFs). However, the discriminative nature of heterogeneous CAFs under glucose starvation remains unknown. In this study, we investigated the changes in the mitochondrial calcium concentration and relevant intracellular machinery in CAFs under glucose-deficient conditions. Xenografted tumor masses were dissected into multiple pieces and subjected to the CAF isolation using magnetically activated cell sorting (MACS). NFs were separated from the normal lung and skin. Under glucose starvation, CAFs from the tumor mass exhibited heterogeneity in cell proliferation, ATP production and calcium concentration. Compared to NFs, mitochondrial calcium concentration was significantly higher in glucose-starved CAFs with upregulation of mitochondrial calcium uniporter (MCU) that led to enhancement of ATP production and cell growth. Intriguingly, treatment of glucose-starved CAFs with oligomycin increased apoptosis by disrupted calcium homeostasis following overactivation of the mPTP. Moreover, oligomycin-induced apoptosis was mitigated by calcium chelation. This study demonstrated that the discriminative calcium influx to mitochondria through MCU coordinated cell growth and apoptosis in glucose-starved CAFs but not in NFs.
60 APPLIED LIFE SCIENCES↗
Complexation of Astatine(III) with Ketones: Roles of NO 3 – Counterion and Exploration of Possible Binding Modes
Ketones have been proven effective in extracting astatine(III) from aqueous solvents. Previous theoretical studies suggested a mechanism where the “sp 2 ” lone pair on the carbonyl oxygen donates electron density into the π system of the AtO + molecular cation to form a dative-type bond. In this study, co-extraction of NO 3 – as AtO(NO 3 )·(O=CR 1 R 2 ) species into the organic phase appears to be a key factor. Adjusting the electronic properties of the ketone, by having an aryl group instead of an alkyl group in the alpha position of the ketone, increased the electron density on C=O, increased the bond strength between the ketone and AtO + , and in turn increased the extraction of 211 At into the organic phase. Extraction with diketones shows dependence on the bridging distance between the two carbonyl moieties, where a C 3 or longer bridge results in a 10-fold increase in extraction into the organic phase. Furthermore, DFT calculations show the longer bridge allows for the chelation of AtO(NO 3 ) by either the second carbonyl or the phenyl ring.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Synthesis, solid-state, solution, and theoretical characterization of an “in-cage” scandium-NOTA complex
A synthetic method was developed that encapsulated Sc 3+ within the macrocyclic chelate, 1,4,7-triazacyclononane-1,4,7-triacetic acid (H 3 NOTA). Encapsulation of Sc 3+ by NOTA 3− was confirmed by single crystal X-ray diffraction, 45 Sc NMR spectroscopy, and DFT calculations.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Nanostructural Analysis of Enzymatic and Non-enzymatic Brown Rot Fungal Deconstruction of the Lignocellulose Cell Wall†
Brown rot (BR) decay mechanisms employ carbohydrate-active enzymes (CAZymes) as well as a unique non-enzymatic chelator-mediated Fenton (CMF) chemistry to deconstruct lignocellulosic materials. Unlike white rot fungi, BR fungi lack peroxidases for lignin deconstruction, and also lack some endoglucanase/cellobiohydrolase activities. The role that the CMF mechanism plays in “opening up” the wood cell wall structure in advance of enzymatic action, and any interaction between CMF constituents and the selective CAZyme suite that BRs possess, is still unclear. Expression patterns for CMF redox metabolites and lytic polysaccharide monooxygenase (LPMO–AA9 family) genes showed that some LPMO isozymes were upregulated with genes associated with CMF at early stages of brown rot by Gloeophyllum trabeum. In the structural studies, wood decayed by the G. trabeum was compared to CMF-treated wood, or CMF-treated wood followed by treatment with either the early-upregulated LPMO or a commercial CAZyme cocktail. Structural modification of decayed/treated wood was characterized using small angle neutron scattering. CMF treatment produced neutron scattering patterns similar to that of the BR decay indicating that both systems enlarged the nanopore structure of wood cell walls to permit enzyme access. Enzymatic deconstruction of cellulose or lignin in raw wood samples was not achieved via CAZyme cocktail or LPMO enzyme action alone. CMF treatment resulted in depolymerization of crystalline cellulose as attack progressed from the outer regions of individual crystallites. Multiple pulses of CMF treatment on raw wood showed a progressive increase in the spacing between the cellulose elementary fibrils (EFs), indicating the CMF eroded the matrix outside the EF bundles, leading to less tightly packed EFs. Peracetic acid delignification treatment enhanced subsequent CMF treatment effects, and allowed both enzyme systems to further increase spacing of the EFs. Moreover, even after a single pulse of CMF treatment, both enzymes were apparently able to penetrate the cell wall to further increase EF spacing. The data suggest the potential for the early-upregulated LPMO enzyme to work in association with CMF chemistry, suggesting that G. trabeum may have adopted mechanisms to integrate non-enzymatic and enzymatic chemistries together during early stages of brown rot decay.
59 BASIC BIOLOGICAL SCIENCES↗
A technique for collection of exudate from pea seedlings
Ethylenediaminetetraacetic acid (EDTA), at concentrations higher than 1.0 millimolar, is phytotoxic to etiolated seedlings of Pisum sativum. Substantial vascular exudation from pea epicotyls could be obtained without tissue damage at 0.5 millimolar EDTA if the solution was buffered at pH 7.5 with sodium N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid. Treated seedlings exuded 950 micrograms (leucine equivalents) of ninhydrin-positive material per day and 870 micrograms (glucose equivalents) of anthrone-positive material per day. Amino acid analysis showed the exudate to have glutamine as the major amido nitrogen containing compound and sucrose was shown to be the major sugar. Radiolabeled tryptophan and sucrose applied to cotyledons were transferred through the epicotyl and into the collection medium. The pH profile for exudation shows half maximal exudation at pH 7.2, indicating the promotion of exudation by EDTA is probably not due simply to Ca2+ chelation.
Non-NASA Center↗
Effects of cations on hormone transport in primary roots of Zea mays
We examined the influence of aluminum and calcium (and certain other cations) on hormone transport in corn roots. When aluminum was applied unilaterally to the caps of 15 mm apical root sections the roots curved strongly away from the aluminum. When aluminum was applied unilaterally to the cap and 3H-indole-3-acetic acid was applied to the basal cut surface twice as much radioactivity (assumed to be IAA) accumulated on the concave side of the curved root as on the convex side. Auxin transport in the apical region of intact roots was preferentially basipetal, with a polarity (basipetal transport divided by acropetal transport) of 6.3. In decapped 5 mm apical root segments, auxin transport was acropetally polar (polarity = 0.63). Application of aluminum to the root cap strongly promoted acropetal transport of auxin reducing polarity from 6.3 to 2.1. Application of calcium to the root cap enhanced basipetal movement of auxin, increasing polarity from 6.3 to 7.6. Application of the calcium chelator, ethylene-glycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraacetic acid, greatly decreased basipetal auxin movement, reducing polarity from 6.3 to 3.7. Transport of label after application of tritiated abscisic acid showed no polarity and was not affected by calcium or aluminum. The results indicate that the root cap is particularly important in maintaining basipetal polarity of auxin transport in primary roots of corn. The induction of root curvature by unilateral application of aluminum or calcium to root caps is likely to result from localized effects of these ions on auxin transport. The findings are discussed relative to the possible role of calcium redistribution in the gravitropic curvature of roots and the possibility of calmodulin involvement in the action of calcium and aluminum on auxin transport.
NASA Discipline Plant Biology↗
Calcium in the regulation of gravitropism by light
The red light requirement for positive gravitropism in roots of corn (Zea mays cv "Merit") provides an entry for examining the participation of calcium in gravitropism. Applications of calcium chelators inhibit the light response. Calcium channel blockers (verapamil, lanthanum) can also inhibit the light response, and a calcium ionophore, A23187, can substitute for light. One can substitute for red light by treatments which have elsewhere been shown to trigger Ca2+ influx into the cytosol, e.g. heat or cold shock. Agents which are known to be agonists of the phosphatidylinositol second messenger system (serotonin, 2,4-dichlorophenoxyacetic acid, deoxycholate) can each partially substitute for the red light, and Li+ can inhibit the light effect. These experiments suggest that the induction of positive gravitropism by red light involves a rise in cytoplasmic Ca2+ concentration, and that a contribution to this end may be made by the phosphatidylinositol second messenger system.
NASA Discipline Number 40-10↗
Activation of G proteins mediates flow-induced prostaglandin E2 production in osteoblasts
Interstitial fluid flow may play a role in load-induced bone remodeling. Previously, we have shown that fluid flow stimulates osteoblast production of cAMP inositol trisphosphate (IP3), and PGE2. Flow-induced increases in cAMP and IP3 were shown to be a result of PG production. Thus, PGE2 production appears to be an important component in fluid flow induced signal transduction. In the present study, we investigated the mechanism of flow-induced PGE2 synthesis. Flow-induced a 20-fold increase in PGE2 production in osteoblasts. Increases were also observed with ALF4-(10mM) (98-fold), an activator of guanidine nucleotide-binding proteins (G proteins), and calcium ionophore A23187 (2 microM) (100-fold) in stationary cells. We then investigated whether flow stimulation is mediated by G proteins and increases in intracellular calcium. Flow-induced PGE2 production was inhibited by the G protein inhibitors GDP beta S (100 microM) and pertussis toxin (1 microgram/ml) by 83% and 72%, respectively. Chelation of extracellular calcium by EGTA (2 mM) and intracellular calcium by quin-2/AM (30 microM) blocked flow stimulation by 87% and 67%, respectively. These results suggest that G proteins and calcium play an important role in mediating mechanochemical signal transduction in osteoblasts.
NASA Discipline Cell Biology↗
Porogen‐Integrated Rapid Oxidation Enables Structured Mesoporous Metal Oxide Films
Structured metal oxide films have promise in optoelectronics, sensing, energy storage, and catalysis but their uptake is predominately limited due to their long and high‐temperature syntheses. Here, in this study, a self‐assembling polymer is used which can act as a chelating fuel source in a solution combustion reaction to generate highly structured mesoporous aluminum oxide films at <250 °C in a matter of minutes through a process termed porogen‐integrated rapid oxidation (PiRO). The resulting films with thicknesses up to 500 nm show an open‐cell, face‐centered cubic structure of spheroidal pores. Further, an additional ligand can be included to control the self‐assembly step to yield both through‐film ordering or tunable disordering for increased pore volume as confirmed by both grazing incidence small angle X‐ray scattering and ellipsometry. Finally, roll‐to‐roll manufacturing with PiRO is demonstrated on flexible polymeric substrates. The method offers a tunable, scalable, low‐temperature, and lower‐cost method to generate large‐area structured mesoporous metal oxide films.
36 MATERIALS SCIENCE↗
Spatial Engineering Direct Cooperativity between Binding Sites for Uranium Sequestration
Preorganization is a basic design principle used by nature that allows for synergistic pathways to be expressed. Herein, a full account of the conceptual and experimental development from randomly distributed functionalities to a convergent arrangement that facilitates cooperative binding is given, thus conferring exceptional affinity toward the analyte of interest. The resulting material with chelating groups populated adjacently in a spatially locked manner displays up to two orders of magnitude improvement compared to a random and isolated manner using uranium sequestration as a model application. This adsorbent shows exceptional extraction efficiencies, capable of reducing the uranium concentration from 5 ppm to less than 1 ppb within 10 min, even though the system is permeated with high concentrations of competing ions. The efficiency is further supported by its ability to extract uranium from seawater with an uptake capability of 5.01 mg g -1 , placing it among the highest-capacity seawater uranium extraction materials described to date. The concept presented here uncovers a new paradigm in the design of efficient sorbent materials by manipulating the spatial distribution to amplify the cooperation of functions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Spectroscopic Evidence of Hyponitrite Radical Intermediate in NO Disproportionation at a MOF-Supported Mononuclear Copper Site
Dianionic hyponitrite (N 2 O 2 2- ) is often proposed, based on model complexes, as the key intermediate in reductive coupling of nitric oxide to nitrous oxide at the bimetallic active sites of heme-copper oxidases and nitric oxide reductases. In this work, we examine the gas-solid reaction of nitric oxide with the metal–organic framework Cu I -ZrTpmC* with a suite of in situ spectroscopies and density functional theory simulations, and identify an unusual chelating N 2 O 2 .- intermediate. These results highlight the advantage provided by site-isolation in metal–organic frameworks (MOFs) for studying important reaction intermediates, and provide a mechanistic scenario compatible with the proposed one-electron couple in these enzymes.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Ligand Protonation Triggers H 2 Release from a Dinickel Dihydride Complex to Give a Doubly “T”-Shaped Dinickel(I) Metallodiradical
The dinickel(II) dihydride complex (1 K ) ofapyrazolate-based compartmental ligand with b-diketiminato (nacnac) chelate arms (L - ), providing two pincer-type {N 3 } binding pockets, has been reported to readily eliminate H 2 and to serve as a masked dinickel(I) species. Discrete dinickel(I) complexes (2 Na , 2 K ) of L - are now synthesized via a direct reduction route. They feature two adjacent T-shaped metalloradicals that are antiferromagnetically coupled, giving an S = 0 ground state. The two singly occupied local d x 2 -y 2 type magnetic orbitals are oriented into the bimetallic cleft, enabling metal–metal cooperative 2 e - substrate reductions as shown by the rapid reaction with H 2 or O 2 . X-ray crystallography reveals distinctly different positions of the K + in 1 K and 2 K , suggesting a stabilizing interaction of K + with the dihydride unit in 1 K . H 2 release from 1 K is triggered by peripheral g-C protonation at the nacnac subunits, which DFT calculations show lowers the barrier for reductive H 2 elimination from the bimetallic cleft.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗