Biologically applicable water-soluble heterogeneous catalysts for para-hydrogen induced polarization

A method for inducing hyperpolarization from para-hydrogen, comprising:

• hydrogenating a substrate, in the presence of ligand-capped nanoparticles and a solvent, by flowing or pressurizing para-hydrogen gas to yield a polarized substrate;
• and
• removing the ligand-capped nanoparticles from the polarized substrate, wherein:
• the ligand-capped nanoparticles comprise metal nanoparticles that are surface-functionalized with organic ligands having a molecular weight of no greater than 300 g/mol, and the organic ligands each have multiple binding moieties as coordinating sites for binding to a nanoparticle surface;
• the metal nanoparticles comprise platinum, palladium, ruthenium, rhodium, or any combination thereof;
• the ligands comprise cysteine;
• wherein a surface coverage of the metal nanoparticles by the organic ligands is at least 4.2 ligands per nm2;
• and
• the metal nanoparticles are bound to larger-sized particles or immobilized on a solid support.