Optical probes and techniques for O2 measurement in live cells and tissue

Abstract

In recent years, significant progress has been achieved in the sensing and imaging of molecular oxygen (O2) in biological samples containing live cells and tissue. We review recent developments in the measurement of O2 in such samples by optical means, particularly using the phosphorescence quenching technique. The main types of soluble O2 sensors are assessed, including small molecule, supramolecular and particle-based structures used as extracellular or intracellular probes in conjunction with different detection modalities and measurement formats. For the different O2 sensing systems, particular attention is paid to their merits and limitations, analytical performance, general convenience and applicability in specific biological applications. The latter include measurement of O2 consumption rate, sample oxygenation, sensing of intracellular O2, metabolic assessment of cells, and O2 imaging of tissue, vasculature and individual cells. Altogether, this gives the potential user a comprehensive guide for the proper selection of the appropriate optical probe(s) and detection platform to suit their particular biological applications and measurement requirements.

Porphyrins for olfaction mimic: The Rome Tor Vergata approach

“…This is, for instance, again the case of molecular oxygen, which is able to quench the phosphorescence of several kinds of metalloporphyrins. Oxygen sensors have been investigated in detail over the years and represent a successful use of porphyrins to detect a single analyte enabling, for instance, the detection of molecular oxygen in living tissues [52].…”

Wide-field TCSPC: methods and applications

“…In life sciences, PLIM is often used to image microenvironment of the probe, such as the oxygen concentration or viscosity [180,181]. The long lifetime increases the sensitivity by giving the probe more time to interact with the environment, and it allows the short-lived autofluorescence from the sample to be discarded.…”

Photon counting phosphorescence lifetime imaging with TimepixCam

“…5, 6 The long lifetime of the probe increases the sensitivity by giving the probe more time to interact with the environment and allowing short-lived autofluorescence from the sample to be discarded. Phosphorescence anisotropy measurements can also be used to study the rotational diffusion of large proteins, whose movement is too slow to be measured with fast nanosecond fluorescence decays.…”