title: Dynamic nuclear polarization in solid samples by electrical-discharge-induced radicals.
abstract: Dynamic nuclear polarization (DNP) is a method for enhancing nuclear magnetic resonance (NMR) signals that has many potential applications in chemistry and medicine. Traditionally, DNP signal enhancement is achieved through the use of exogenous radicals mixed in a solution with the molecules of interest. Here we show that proton DNP signal enhancements can be obtained for solid samples without the use of solvent and exogenous radicals. Radicals are generated primarily on the surface of a solid sample using electrical discharges. These radicals are found suitable for DNP. They are stable under moderate vacuum conditions, yet readily annihilate upon compound dissolution or air exposure. This feature makes them attractive for use in medical applications, where the current variety of radicals used for DNP faces regulatory problems. In addition, this solvent-free method may be found useful for analytical NMR of solid samples which cannot tolerate solvents, such as certain pharmaceutical products.
authors.affiliation: Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Itai
authors.initials: I
authors.lastname: Katz
authors.affiliation: Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel. Electronic address: ab359@tx.technion.ac.il.
authors.forename: Aharon
authors.initials: A
authors.lastname: Blank
mesh_terms: D002626:Chemistry, Pharmaceutical; D004574:Electromagnetic Fields; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry*; D008358:Mannose / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D012822:Silicon Dioxide / Q000737:chemistry; D012995:Solubility; D012997:Solvents; D013395:Sucrose / Q000737:chemistry
chemical_list: D005609:Free Radicals; D011522:Protons; D012997:Solvents; D013395:Sucrose; D012822:Silicon Dioxide; D008358:Mannose
keywords: DNP; Dynamic nuclear polarization; Metabolic MRI; NMR; Surface NMR