Parahydrogen-Induced Hyperpolarisation For Microfluidic Perfusion Culture

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Nuclear magnetic resonance (NMR) is one of the most powerful tools forinvestigating the structure, composition, and dynamics of living and non-livingmatter. Its sensitivity is limited by the degree of alignment of nuclear spins,which is small even in the strongest magnets. Hyperpolarisation techniquessuch as parahydrogen-induced polarisation can produce much better spinalignments, offering corresponding increases in sensitivity.paraQchip aims provide lab-on-a-chip (LoC) cultures of cells with hyperpolarisedmetabolites (pyruvate, fumarate) for high-sensitivity NMR monitoring of metabolism,by integrating all steps of parahydrogen-induced polarisation (PHIP) onto thechip. To this end, we propose an interdisciplinary research programme that usesquantitative modelling of spin dynamics, transport, and kinetic processesin tandem with experimental quantification of reaction and transport kinetics toinform the design of the microfluidic chip layout, NMR detector, radiofrequencypulse sequences, and operation parameters such as flow rates, reagent concentrations,solvents, and temperature. The main challenge lies in the concerted operationof the hydrogenation, polarisation transfer, and purification steps, whichmust all be completed before nuclear relaxation destroys the hyperpolarisation.The proposed research consists of four work packages, each led by oneof the Co-PIs. WP 1 (Kuprov) focusses on modelling, using a novel approachthat treats spin and spatial degrees of freedom on an equal footing.WP 2 (Levitt) deals with the required transfer of polarisation from theparahydrogen spin order to the target metabolite. This requires designof a novel microfluidic NMR probe system with separate detectors forthe transfer step and for downstream observation. WP 3 (Whitby) will focuson the chemical aspects, including hydrogenation, cleavage, and purification.Finally, WP 4 (Utz) deals with the microfluidic integration of these steps.LoC devices provide detailed control over the growth conditions of cells,tissues ("organ-on-a-chip"), and small organisms, providing valuable modelssupporting the development of diagnostics and therapies, and drug safetytesting. NMR spectroscopy could be of great use in this context, as it allowsnon-invasive quantification of metabolic processes. However, the limitedsensitivity of conventional NMR is exacerbated at the microlitre volumescale of LoC devices. paraQchip will address that, pushing the limitof detection from the millimolar concentration range down to micromolar. This willallow detailed in-situ observation of metabolic processes in microfluidiccell cultures as well as tissue and organ models, with many applicationsin disease modelling, drug testing, and other aspects of the life sciences.Microfluidic implementation of PHIP will also lead to deeper understandingof the interplay between the hydrogenation reaction mechanism and nuclearspin relaxation processes. The computational tools developed and validatedthrough paraQchip will benefit the development of hyperpolarised magneticresonance imaging techniques.