Oxygen Tension of Living Cells and Tissues Based on Phosphorescence Lifetime Measurements

Abstract

Molecular oxygen plays a pivotal role in aerobic organism as a terminal electron acceptor in electron transport chain in mitochondria. Oxygen deprivation (hypoxia) in organism is closely linked to various hypoxia-related cellular functions and diseases including cancer, cerebral infarction, and chronic kidney disease. The quantitative and real-time detection of oxygen levels in living cells and tissues is therefore of great importance in elucidating fundamental studies of cellular metabolism and hypoxia-related diseases. This review focuses on recent advances in biological oxygen sensing and imaging based on phosphorescence lifetime measurements using phosphorescent probes. Principle of oxygen sensing by means of phosphorescence quenching, recent advances of phosphorescent oxygen probes and their applications to intracellular and in vivo oxygen measurements are described, emphasizing the usefulness of Pd(II)- and Pt(II)-porphyrins and iridium(III) complexes as biological oxygen probes.