Riccardo Balzan
École Polytechnique Fédérale de Lausanne
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Publication
Featured researches published by Riccardo Balzan.
Physical Chemistry Chemical Physics | 2013
Tian Cheng; Andrea Capozzi; Yuhei Takado; Riccardo Balzan; Arnaud Comment
The most versatile method to increase liquid-state (13)C NMR sensitivity is dissolution dynamic nuclear polarization. The use of trityl radicals is usually required to obtain very large (13)C polarization via this technique. We herein demonstrate that up to 35% liquid-state (13)C polarization can be obtained in about 1.5 h using ubiquitous nitroxyl radicals in (13)C-labeled sodium salts by partially deuterating the solvents and using a polarizer operating at 1 K and 7 T.
Contrast Media & Molecular Imaging | 2016
Riccardo Balzan; Mor Mishkovsky; Yana Simonenko; Ruud B. van Heeswijk; Rolf Gruetter; Uzi Eliav; Gil Navon; Arnaud Comment
Hyperpolarization by dissolution dynamic nuclear polarization (DNP) is a versatile technique to dramatically enhance the nuclear magnetic resonance (NMR) signal intensity of insensitive long-T1 nuclear spins such as (6)Li. The (6)Li longitudinal relaxation of lithium ions in aqueous solutions strongly depends on the concentration of paramagnetic species, even if they are present in minute amounts. We herein demonstrate that blood oxygenation can be readily detected by taking advantage of the (6)Li signal enhancement provided by dissolution DNP, together with the more than 10% decrease in (6)Li longitudinal relaxation as a consequence of the presence of paramagnetic deoxyhemoglobin.
Magnetic Resonance in Chemistry | 2017
Riccardo Balzan; Laetitia Fernandes; Laetitia Pidial; Arnaud Comment; Bertrand Tavitian; Paul R. Vasos
Pyruvate membrane crossing and its lactate dehydrogenase‐mediated conversion to lactate in cells featuring different levels of expression of membrane monocarboxylate transporters (MCT4) were probed by dissolution dynamic nuclear polarization‐enhanced NMR. Hyperpolarized 13C‐1‐labeled pyruvate was transferred to suspensions of rodent tumor cell carcinoma, cell line 39. The pyruvate‐to‐lactate conversion rate monitored by dissolution dynamic nuclear polarization‐NMR in carcinoma cells featuring native MCT4 expression level was lower than the rate observed for cells in which the human MCT4 gene was overexpressed. The enzymatic activity of lactate dehydrogenase was also assessed in buffer solutions, following the real‐time pyruvate‐to‐lactate conversion speeds at different enzyme concentrations. Copyright
Journal of Visualized Experiments | 2016
Riccardo Balzan; Laetitia Fernandes; Arnaud Comment; Laetitia Pidial; Bertrand Tavitian; Paul R. Vasos
The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of metabolic transformations. Hyperpolarization via dissolution DNP circumvents part of the sensitivity issues thanks to the large out-of-equilibrium nuclear magnetization stemming from the electron-to-nucleus spin polarization transfer. The high NMR signal obtained can be used to monitor chemical reactions in real time. The downside of hyperpolarized NMR resides in the limited time window available for signal acquisition, which is usually on the order of the nuclear spin longitudinal relaxation time constant, T1, or, in favorable cases, on the order of the relaxation time constant associated with the singlet-state of coupled nuclei, TLLS. Cellular uptake of endogenous molecules and metabolic rates can provide essential information on tumor development and drug response. Numerous previous hyperpolarized NMR studies have demonstrated the relevancy of pyruvate as a metabolic substrate for monitoring enzymatic activity in vivo. This work provides a detailed description of the experimental setup and methods required for the study of enzymatic reactions, in particular the pyruvate-to-lactate conversion rate in presence of lactate dehydrogenase (LDH), by hyperpolarized NMR.
Granular Matter | 2013
Riccardo Balzan; Alessandro Luigi Sellerio; Daniele Mari; G. Gremaud
Applied Magnetic Resonance | 2015
Riccardo Balzan; Alessandro Luigi Sellerio; Daniele Mari
Proceedings of the 4th International DNP Symposium | 2013
Riccardo Balzan; Andrea Capozzi; Tian Cheng; Arnaud Comment
4th International DNP Symposium | 2013
Adam N. Smith; Daniel P. Downes; Riccardo Balzan; Andrea Capozzi; Arnaud Comment; Joanna R. Long
4th International DNP Symposium | 2013
Tian Cheng; Andrea Capozzi; Yuhei Takado; Riccardo Balzan; Arnaud Comment
4th International DNP Symposium | 2013
Mor Mishkovsky; Emine Can; Leila Drissi Daoudi; Yves Pilloud; Riccardo Balzan; Rolf Gruetter; Arnaud Comment