Phosphorescence metal complexes for sensing physiological parameters in biological objects

Abstract

Oxygen concentration as well as pH and temperature are paramount physiological parameters of living systems. Monitoring the values of these parameters in biological objects makes possible evaluation of the object’s metabolic status, detection of cells, tissues, organs dysfunctions, or analysis of the response to the therapy used to combat the pathology. Among a number of probes applicable for noninvasive determination of selected parameters, it is necessary to highlight the phosphorescent complexes of transition metals due to their ability to attain the desirable photophysical characteristics, selectivity of sensory response in a biological media, and high bleaching stability. One of the most promising modes to acquire the phosphorescent probe response onto biologically relevant analytes is the mode based on emission lifetime measurements. This modality is independent of the probe concentration and variations in optical properties of the samples under study. Since the key feature of transition metal complexes is the triplet nature of luminescence, experiments in this imaging modality are called «Phosphorescence Lifetime Imaging» or PLIM. Much longer phosphorescence lifetimes compared to the nanosecond values inherent for the fluorescence of the organic dyes ensure a more convenient and wider interval of measurable values. Moreover, the transition metal complexes display large Stokes shifts allowed to separate the emission of the probe from the excitation radiation and autofluorescence. All of the above mentioned properties significantly improve the quality of the resulting image. In this lecture major aspects of the phosphorescent metal complexes application for the study of biological objects characteristics, such as oxygen concentration, pH and temperature, will be presented and analyzed.

Speaker

Kristina Kisel
Saint Petersburg State University
Russia

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