Permeability Studies of Redox-Sensitive Nitroxyl Spin Probes Through Lipid Membranes Using an L-Band ESR Spectrometer

• Published in: Applied magnetic resonance 2013-04, Vol.44 (4), p.439-447
• Main Authors: Milton Franklin Benial, A., Kumara Dhas, M., Ichikawa, Kazuhiro, Yamada, Ken-ichi, Hyodo, Fuminori, Jawahar, A., Utsumi, Hideo
• Format: Article
• Language: English
• Subjects: Atoms and Molecules in Strong Fields; Chemical partition; Cholesterol; Coupling; Deuteration; Electron paramagnetic resonance; Electron spin; Free radicals; Laser Matter Interaction; Lipids; Liposomes; Membranes; Organic Chemistry; Oxidation; Parameters; Particle size; Permeability; Phase transitions; Physical Chemistry; Physics; Physics and Astronomy; Rotational spectra; Solid State Physics; Spectroscopy/Spectrometry; Spectrum analysis; Spin resonance; Ultrasonic imaging
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-012-0383-0

Electron spin resonance (ESR) studies were carried out for 2 mM 14 N-labeled deuterated 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) and 3-carboxy-2,2,5,5,-tetramethyl-pyrrolidin-1-oxyl (carboxy-PROXYL) in pure water and various concentrations of liposomal solution by using an L-band ESR spectrometer. The ESR parameters, such as the line width, hyperfine coupling constant, g -factor, rotational correlation time and partition parameter, were reported for the samples. The changes in the line width were observed for 14 N-labeled deuterated MC-PROXYL and carboxy-PROXYL in liposomal solution. The hyperfine coupling constant was observed for both nitroxyl spin probes. The permeable and impermeable nature of nitroxyl radicals was demonstrated using the ESR L-band spectra. The rotational correlation time increases with increasing concentration of liposome. The partition parameter for 14 N-labeled deuterated MC-PROXYL in liposomal solution increases with increasing concentration of liposome, which reveals that the nitroxyl spin probe permeates into lipid membrane. The lipid peaks were observed for 2 mM 14 N-labeled deuterated MC-PROXYL in 200, 300 and 400 mM liposomal concentration. The lipid peaks were not observed for 14 N-labeled deuterated carboxy-PROXYL. These results indicate the permeable and impermeable nature of 14 N-labeled deuterated nitroxyl spin probe.