Olga S. Finikova

Oxygen Microscopy by Two‐Photon‐Excited Phosphorescence

High-resolution images of oxygen distributions in microheterogeneous samples are obtained by two-photon laser scanning microscopy (2P LSM), using a newly developed dendritic nanoprobe with internally enhanced two-photon absorption (2PA) cross-section. In this probe, energy is harvested by a 2PA antenna, which passes excitation onto a phosphorescent metalloporphyrin via intramolecular energy transfer. The 2P LSM allows sectioning of oxygen gradients with near diffraction-limited resolution, and lifetime-based acquisition eliminates dependence on the local probe concentration. The technique is validated on objects with a priori known oxygen distributions and applied to imaging of pO(2) in cells.

First highly distorted π-extended Fe(II) porphyrin – a unique model to elucidate factors affecting the electrochemical potentials

The preparation, X-ray crystal structure and electrochemistry of a new poly-substituted air-stable tetrabenzoporphyrin iron(II) bis-pyridine complex (1) is reported.

Measuring Oxygen in Living Tissue: Intravascular, Interstitial, and “Tissue” Oxygen Measurements

Oxygen dependent quenching of phosphorescence has been used to measure the oxygen pressure in both the vasculature of the microcirculation and the interstitial spaces of resting muscle tissue. Oxygen sensitive molecules were either dissolved in the blood (intravascular space) or micro-injected into the interstitial space and the distributions, histograms, of the oxygen pressure were measured. The mean oxygen pressures are higher in the blood than in the interstitial space but the oxygen pressures in the lowest 10% of the two spaces were not significantly different, indicating there is minimal (< 1 mm Hg) oxygen gradient between the two spaces in the capillary bed.

An expedient synthesis of substituted tetraaryltetrabenzoporphyrins

A simple route to tetraaryltetrabenzoporphyrins (Ar4TBPs) is developed; the procedure allows for the introduction of substituents on both benzo- and phenyl-rings and employs readily available, inexpensive components.

Oxygen Microscopy with Two-Photon-Enhanced Phosphorescent Nanoprobes

A new method for non-invasive high-resolution imaging of oxygen distributions using phosphorescent nanoprobes with enhanced two-photon absorption cross-sections is being developed. Validation of the phosphorescence lifetime imaging microscope and characterization of new probes was performed.

Microscopic Imaging of Oxygen by Two-Photon-Excited Phosphorescence

Microscopic oxygen distributions in heterogeneous phantoms and cells were visualized by means of two-photon laser scanning microscopy, using phosphorescent probes with controllable quenching parameters and enhanced two-photon absorption cross-sections.