Singlet oxygen, the lowest excited electronic state of molecular oxygen, is a 'mature citizen' that has been studied for many years from a range of perspectives.  Among other things, singlet oxygen has a unique chemistry that results in the oxygenation of many organic molecules relevant to biological function (e.g., proteins, lipids, DNA).  In this way, singlet oxygen plays important roles in mechanisms of cell signaling, cell stimulation and cell death.Singlet oxygen is commonly produced in a photosensitized process wherein light is absorbed by a given molecule (the so-called sensitizer) followed by energy transfer from the excited state sensitizer to ground state oxygen.  Not only is the production of singlet oxygen in this way a natural phenomenon (i.e., we live in a world of light, oxygen, and sensitizers) and is used as a clinical tool (i.e., photodynamic therapy), it also provides a readily-controlled method by which singlet oxygen can be produced in mechanistic studies of events that occur in mammalian cells.We have a multi-faceted program in which the behavior of singlet oxygen is examined in time- and space-resolved experiments performed at the level of a single cell.  As part of this work, we have been particularly interested in developing and exploiting methods to selectively control the photosensitized production and subsequent detection of singlet oxygen. Within this framework, I will discuss several projects carried-out in our group.  These include (1) the design, characterization and implementation of protein-encased chromophores for the two-photon photosensitized production of singlet oxygen, (2) the accurate control of the 'dose' of intracellular singlet oxygen to yield a stimulating rather than cytotoxic effect, and (3) the design and characterization of organic-based fluorescent probes for singlet oxygen that can be used to complement the method of monitoring intracellular singlet oxygen by its time-resolved phosphorescence at 1275 nm.

Singlet oxygen in single cell experiments: Imparting control and selectivity to the creation and detection of this reactive oxygen species

248th National Meeting (2014)

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