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Lifetime of Parahydrogen in Aqueous Solutions and Human Blood.

ABSTRACT: Molecular hydrogen has unique nuclear spin properties. Its nuclear spin isomer, parahydrogen (pH2 ), was instrumental in the early days of quantum mechanics and allows to boost the NMR signal by several orders of magnitude. pH2- induced polarization (PHIP) is based on the survival of pH2 spin order in solution, yet its lifetime has not been investigated in aqueous or biological media required for in?vivo applications. Herein, we report longitudinal relaxation times (T1 ) and lifetimes of pH2 ( ?POC ) in methanol and water, with or without O2 , NaCl, rhodium-catalyst or human blood. Furthermore, we present a relaxation model that uses T1 and ?POC for more precise theoretical predictions of the H2 spin state in PHIP experiments. All measured T1 values were in the range of 1.4-2?s and ?POC values were of the order of 10-300 minutes. These relatively long lifetimes hold great promise for emerging in?vivo implementations and applications of PHIP.

SUBMITTER: Schmidt AB

PROVIDER: S-EPMC7687157 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Lifetime of Parahydrogen in Aqueous Solutions and Human Blood.

Schmidt Andreas B AB Wörner Jakob J Pravdivtsev Andrey A Knecht Stephan S Scherer Harald H Weber Stefan S Hennig Jürgen J von Elverfeldt Dominik D Hövener Jan-Bernd JB

Chemphyschem : a European journal of chemical physics and physical chemistry 20190912 19

Molecular hydrogen has unique nuclear spin properties. Its nuclear spin isomer, parahydrogen (pH2 ), was instrumental in the early days of quantum mechanics and allows to boost the NMR signal by several orders of magnitude. pH2- induced polarization (PHIP) is based on the survival of pH2 spin order in solution, yet its lifetime has not been investigated in aqueous or biological media required for in vivo applications. Herein, we report longitudinal relaxation tim ...[more]

PMID: 31479580

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Project description:Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface-active dye, was added to the surfactant solution. The spreading progresses through a series of events. Marangoni stresses initiate the convective spreading of the drop. Simultaneously, surfactant escapes across the drop's contact line within a second of deposition and causes a change in subphase surface tension outside the drop on the order of 1 mN/m. Convective spreading of the drop ends within 2-3 s of drop deposition, when a new interfacial tension balance is achieved. Surfactant escape depletes the drop of surfactant, and the residual drop takes the form of a static lens of nonzero contact angle. On longer time scales, the surfactant dissolves into the subphase. The lens formed by the water in the deposited drop persists for as long as 3 min after the convective spreading process ends due to the long diffusional time scales associated with the underlying entangled polymer solution. The persistence of the lens suggests that the drop phase behaves as if it were immiscible with the subphase during this time period. Whereas surfactant escapes the spreading drop and advances on the subphase/vapor interface, hydrophilic dye molecules in the drop do not escape but remain with the drop throughout the convective spreading. The quasi-immiscible nature of the spreading event suggests that the chemical properties of the surfactant and subphase are much less important than their physical properties, consistent with prior qualitative studies of spreading of different types of surfactants on entangled polymer subphases: the selection of surfactant for pulmonary delivery applications may be limited only by physical and toxicological considerations. Further, the escape of surfactant from individual drops may provide an additional spreading mechanism in the lung, as hydrodynamic and/or surface pressure repulsions may drive individual droplets apart after deposition.

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Lifetime of Parahydrogen in Aqueous Solutions and Human Blood.

Publications

Lifetime of Parahydrogen in Aqueous Solutions and Human Blood.

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