title: Evaluation of oxygen-response times of phthalocyanine-based crystalline paramagnetic spin probes for EPR oximetry.
abstract: The goal of the present study was to evaluate the temporal response of particulate-based EPR oximetry probes to changes in partial pressure of oxygen (pO(2)). In order to accurately evaluate the oxygen-response time, we developed a method for rapid modulation of pO(2) in a chamber containing the probe using an oscillator-driven speaker-diaphragm setup. The apparatus was capable of producing sinusoidal changes in pO(2) at frequencies up to 300 Hz or more. The pressure-modulation setup was used to evaluate the temporal response of some of the most commonly used phthalocyanine-based particulate probes. For validation, the time-response of the probes was compared to that of a high sensitivity pressure sensor. The results revealed that some particulate probes could respond to changes in pO(2) with a temporal response of 3.3 ms (300 Hz). The observations were interpreted in the light of their crystalline packing in favor of oxygen diffusion. The results of the present study should enable the selection of probes for oximetry applications requiring high temporal resolution.
authors.affiliation: Center for Biomedical EPR Spectroscopy and Imaging, The Dorothy M. Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, 420 West 12th Avenue, TMRF-114, Columbus, OH 43210, USA.
authors.forename: Deepti S
authors.initials: DS
authors.lastname: Vikram
authors.forename: Rizwan
authors.initials: R
authors.lastname: Ahmad
authors.forename: Ramasamy P
authors.initials: RP
authors.lastname: Pandian
authors.forename: Sergey
authors.initials: S
authors.lastname: Petryakov
authors.forename: Periannan
authors.initials: P
authors.lastname: Kuppusamy
mesh_terms: D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D015394:Molecular Structure; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000032:analysis*; D012680:Sensitivity and Specificity
chemical_list: D007211:Indoles; D054833:Isoindoles; D010100:Oxygen; C013647:phthalocyanine