Issue 10, 2007

Measuring the lifetime of singlet oxygen in a single cell: addressing the issue of cell viability

Abstract

Singlet molecular oxygen, O2(a1Δg), has been detected from single neurons and HeLa cells in time-resolved optical experiments by its 1270 nm phosphorescence (a1Δg → X3Σg) upon irradiation of a photosensitizer incorporated into the cell. The cells were maintained in a buffered medium and their viability was assessed by live/dead assays. To facilitate the detection of singlet oxygen, intracellularH2O was replaced with D2O by an osmotic de- and rehydration process. The effect of this insult on the cells was likewise assessed. The data indicate that, in the complicated transition from a “live” to “dead” cell, the majority of our cells have the metabolic activity and morphology characteristic of a live cell. Quenching experiments demonstrate that the singlet oxygen lifetime in our cells is principally determined by interactions with intracellularwater and not by interactions with other cell constituents. The data indicate that in a viable, metabolically-functioning, and H2O-containing cell, the lifetime of singlet oxygen is ∼3 µs. This is consistent with our previous reports, and confirms that the singlet oxygen lifetime in a cell is much longer than hitherto believed. This implies that, in a cell, singlet oxygen is best characterized as a selective rather than reactive intermediate. This is important when considering roles played by singlet oxygen as a signaling agent and as a component in events that result in cell death. The data reported herein also demonstrate that spatially-resolved optical probes can be used to monitor selected events in the light-induced, singlet-oxygen-mediated death of a single cell.

Graphical abstract: Measuring the lifetime of singlet oxygen in a single cell: addressing the issue of cell viability

Article information

Article type
Paper
Submitted
15 May 2007
Accepted
13 Jul 2007
First published
30 Jul 2007

Photochem. Photobiol. Sci., 2007,6, 1106-1116

Measuring the lifetime of singlet oxygen in a single cell: addressing the issue of cell viability

S. Hatz, J. D. C. Lambert and P. R. Ogilby, Photochem. Photobiol. Sci., 2007, 6, 1106 DOI: 10.1039/B707313E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements