Title: 2D Gadolinium Oxide Nanoplates as T 1 Magnetic Resonance Imaging Contrast Agents
Abstract Millions of people a year receive magnetic resonance imaging (MRI) contrast agents for the diagnosis of conditions as diverse as fatty liver disease and cancer. Gadolinium chelates, which provide preferredT1contrast, are the current standard but face an uncertain future due to increasing concerns about their nephrogenic toxicity as well as poor performance in high‐field MRI scanners. Gadolinium‐containing nanocrystals are interesting alternatives as they bypass the kidneys and can offer the possibility of both intracellular accumulation and active targeting. Nanocrystal contrast performance is notably limited, however, as their organic coatings block water from close interactions with surface Gadoliniums. Here, these steric barriers to water exchange are minimized through shape engineering of plate‐like nanocrystals that possess accessible Gadoliniums at their edges. Sulfonated surface polymers promote second‐sphere relaxation processes that contribute remarkable contrast even at the highest fields (r1= 32.6 × 10−3mGd−1s−1at 9.4 T). These noncytotoxic materials release no detectable free Gadolinium even under mild acidic conditions. They preferentially accumulate in the liver of mice with a circulation half‐life 50% longer than commercial agents. These features allow theseT1MRI contrast agents to be applied for the first time to the ex vivo detection of nonalcoholic fatty liver disease in mice. more »« less
Karbalaei, Sana; Franke, Alicja; Zahl, Achim; Pokkuluri, P Raj; Beyers, Ronald J; Ivanović-Burmazović, Ivana; Goldsmith, Christian R
(, Chemical Communications)
A highly air- and water-stable Fe(ii) complex with a fluorinated ligand has a strong19F MRI signal but is a poorT1-weighted1H MRI contrast agent. Upon oxidation by H2O2, the19F MRI signal decays as the relaxivity for1H MRI markedly improves.
Magnetic resonance imaging (MRI) is a routinely used imaging technique in medical diagnostics. To enhance the quality of MR images, contrast agents (CAs) are used, which account for nearly 40% of MRI exams in the clinic globally. The most used CAs are gadolinium-based CAs (GBCAs) but the use of GBCAs has been linked with metal-deposition in vital organs. Gadolinium deposition has been shown to be correlated with nephrogenic systemic fibrosis, a fibrosis of the skin and internal organs. Therefore, there is an unmet need for a new CA alternative to GBCAs for T 1 -weighted Ce-MRI. Herein, we designed paramagnetic ferric iron( iii ) ion-chelated poly(lactic- co -glycolic)acid nanoparticle formulation and routinely examined their application in Ce-MRI using clinical and ultra-high-field MRI scanners. Nanoparticles were monodispersed and highly stable at physiological pH over time with the hydrodynamic size of 130 ± 12 nm and polydispersity index of 0.231 ± 0.026. The T 1 -contrast efficacy of the nanoparticles was compared with commercial agent gadopentetate dimeglumine, called Magnevist®, in aqueous phantoms in vitro and then validated in vivo by visualizing an angiographic map in a clinical MRI scanner. Relaxivities of the nanoparticles in an aqueous environment were r 1 = 10.59 ± 0.32 mmol −1 s −1 and r 1 = 3.02 ± 0.14 mmol −1 s −1 at 3.0 T and 14.1 T measured at room temperature and pH 7.4, respectively. The clinically relevant magnetic field relaxivity is three times higher compared to the Magnevist®, a clinical GBCA, signifying its potential applicability in clinical settings. Moreover, iron is an endogenous metal with known metabolic safety, and the polymer and phospholipids used in the nanoconstruct are biodegradable and biocompatible components. These properties further put the proposed T 1 agent in a promising position in contrast-enhanced MRI of patients with any disease conditions.
DeAguero, Joshua; Howard, Tamara; Kusewitt, Donna; Brearley, Adrian; Ali, Abdul-Mehdi; Degnan, James H.; Jett, Stephen; Watt, John; Escobar, G. Patricia; Dokladny, Karol; et al
(, Scientific Reports)
Abstract The leitmotifs of magnetic resonance imaging (MRI) contrast agent-induced complications range from acute kidney injury, symptoms associated with gadolinium exposure (SAGE)/gadolinium deposition disease, potentially fatal gadolinium encephalopathy, and irreversible systemic fibrosis. Gadolinium is the active ingredient of these contrast agents, a non-physiologic lanthanide metal. The mechanisms of MRI contrast agent-induced diseases are unknown. Mice were treated with a MRI contrast agent. Human kidney tissues from contrast-naïve and MRI contrast agent-treated patients were obtained and analyzed. Kidneys (human and mouse) were assessed with transmission electron microscopy and scanning transmission electron microscopy with X-ray energy-dispersive spectroscopy. MRI contrast agent treatment resulted in unilamellar vesicles and mitochondriopathy in renal epithelium. Electron-dense intracellular precipitates and the outer rim of lipid droplets were rich in gadolinium and phosphorus. We conclude that MRI contrast agents are not physiologically inert. The long-term safety of these synthetic metal–ligand complexes, especially with repeated use, should be studied further.
Méndez-Delgado, J E; Skillman, E D; Aver, E; Morisset, C; Esteban, C; García-Rojas, J; Kreckel, K; Rogers, N_S J; Rosales-Ortega, F F; Arellano-Córdova, K Z; et al
(, The Astrophysical Journal)
Abstract The physics of recombination lines in the Heisinglet system is expected to be relatively simple, supported by accurate atomic models. We examine the intensities of Heisingletsλ3614, λ3965, λ5016, λ6678, and λ7281 and the triplet Heiλ5876 in various types of ionized nebulae and compare them with theoretical predictions to test the validity of the “Case B” recombination scenario and the assumption of thermal homogeneity. Our analysis includes 85 spectra from Galactic and extragalactic Hiiregions, 90 from star-forming galaxies, and 218 from planetary nebulae, all compiled by the Deep Spectra of Ionized Regions Database Extended (DESIRED-E) project. By evaluating the ratios Heiλ7281/λ6678 and Heiλ7281/λ5876, we determineTe(Hei) and compare it with direct measurements ofTe([Oiii]λ4363/λ5007). We find thatTe(Hei) is systematically lower thanTe([Oiii]) across most objects and nebula types. Additionally, we identify a correlation between the abundance discrepancy factor (ADF(O2+)) and the differenceTe([Oiii]) –Te(Hei) for planetary nebulae. We explore two potential explanations: photon loss fromn1P → 11Stransitions and temperature inhomogeneities. Deviations from “Case B” may indicate photon absorption by Hirather than Heiand/or generalized ionizing photon escape, highlighting the need for detailed consideration of radiative transfer effects. If temperature inhomogeneities are widespread, identifying a common physical phenomenon affecting all ionized nebulae is crucial. Our results suggest that both scenarios can contribute to the observed discrepancies.
Rad, Vahid; A_Shamsabadi, Ahmad; Aghaei, Amir; Wyatt, Brian C; Jahanbakhshi, Farzaneh; Thakur, Anupma; Fang, Hui; Sadrzadeh, Mohtada; Anasori, Babak; Rappe, Andrew M; et al
(, ChemSusChem)
Ti3C2TxMXene membranes have attracted considerable interest due to their exceptional water transport properties, yet the role of cation intercalation on governing transport remains poorly understood. In this experimental and theoretical study, it shows how intercalation with K+, Na+, Li+, Ca2+, and Mg2+modulates both the nanochannel architecture and water flux of Ti3C2Txmembranes. Unlike in graphene oxide analogs, cations with larger hydration diameters in Ti3C2Txexpand the interlayer spacing, widening flow channels, enhancing slip length of these nanochannels, and boosting water flux from 31.45 to 61.86 L m−2 h−1. To overcome intrinsically poor adhesion of Ti3C2Txto polymeric supports, this study incorporates a thin polyvinyl‐alcohol interlayer, which substantially enhances mechanical robustness and structural integrity. Together, these findings elucidate how cation hydration controls water transport and offer a flexible strategy for tailoring MXene membrane performance.
@article{osti_10627150,
place = {Country unknown/Code not available},
title = {2D Gadolinium Oxide Nanoplates as T 1 Magnetic Resonance Imaging Contrast Agents},
url = {https://par.nsf.gov/biblio/10627150},
DOI = {10.1002/adhm.202001780},
abstractNote = {Abstract Millions of people a year receive magnetic resonance imaging (MRI) contrast agents for the diagnosis of conditions as diverse as fatty liver disease and cancer. Gadolinium chelates, which provide preferredT1contrast, are the current standard but face an uncertain future due to increasing concerns about their nephrogenic toxicity as well as poor performance in high‐field MRI scanners. Gadolinium‐containing nanocrystals are interesting alternatives as they bypass the kidneys and can offer the possibility of both intracellular accumulation and active targeting. Nanocrystal contrast performance is notably limited, however, as their organic coatings block water from close interactions with surface Gadoliniums. Here, these steric barriers to water exchange are minimized through shape engineering of plate‐like nanocrystals that possess accessible Gadoliniums at their edges. Sulfonated surface polymers promote second‐sphere relaxation processes that contribute remarkable contrast even at the highest fields (r1= 32.6 × 10−3mGd−1s−1at 9.4 T). These noncytotoxic materials release no detectable free Gadolinium even under mild acidic conditions. They preferentially accumulate in the liver of mice with a circulation half‐life 50% longer than commercial agents. These features allow theseT1MRI contrast agents to be applied for the first time to the ex vivo detection of nonalcoholic fatty liver disease in mice.},
journal = {Advanced Healthcare Materials},
volume = {10},
number = {11},
publisher = {Wiley-VCH GmbH},
author = {Stinnett, Gary and Taheri, Nasim and Villanova, Jake and Bohloul, Arash and Guo, Xiaoting and Esposito, Edward P and Xiao, Zhen and Stueber, Deanna and Avendano, Carolina and Decuzzi, Paolo and Pautler, Robia G and Colvin, Vicki L},
}
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