Polycarboxylate Fluorescent Indicators as Ion Concentration Probes in Biological Systems

Abstract

A large number of techniques have been applied to monitor the function of free metal ions in biological systems. Fluorescent ion probes have evolved into an extremely useful tool for contemporary experimentalists. Polycarboxylate indicators are widely used in the determination of metal ion concentrations, especially due to their cell membrane permeability. The design of these probes required detailed knowledge in related fields of medicine, biology, and chemistry, and their preparation demanded the expertise of organic synthesis. In this review, the basic rationale for the selection of particular chemical structures are analyzed, synthetic pathways leading to the desired structures are presented, often via a retrosynthetic approach, and properties and relative advantages of the use of these probes are described. References to specific applications are limited, given the large number of reviews on related subjects. Topics such as those related to dextran conjugates that are broad enough to be the subject of a different review are not included, and leakage resistance and near-membrane probes are mentioned briefly in separate sections, although these are chemically similar to typical polycarboxylate dyes. While reference to topics mentioned in related reviews is unavoidable, presentation of material in this review is from the point of view of a medicinal chemist rather than that of the many experts using these pioneering techniques.

Kinetic changes in tetanic Ca2+ transients in enzymatically dissociated muscle fibres under repetitive stimulation

“…Unfortunately, with the slow, high‐affinity Ca 2+ dyes that have been used to demonstrate the reduction of the tetanic Ca 2+ transient amplitude during fatigue, it is difficult to reliably demonstrate kinetic changes of the transients. A new generation of Ca 2+ dyes has been available during the last decade and some of them can faithfully track the kinetics of Ca 2+ signalling during muscle contraction (Katerinopoulos & Foukaraki, 2002; Hollingworth et al . 2009; Calderón et al .…”

The Coumarin Moiety as Chromophore of Fluorescent Ion Indicators in Biological Systems

“…There is lately a rapidly growing interest in the development of fluorescent probes with high selectivity for their cellular component-targets. As a result a considerable number of publications describing the synthesis and spectral profile studies of ion-selective fluorescent probes, including coumarin-type sensors, appeared in the literature [8][9][10][11].…”

“…Scheme(11). Aza-and diaza-crown ether-type ion indicators linked to coumarin 153. undergoes a red shift from 410 to 450 nm at full complexation whereas the emission was red shifted only by 10 nm to 496 nm.…”

Synthesis and Characterization of a New Red-Emitting Ca2+ Indicator, Calcium Ruby

“…Measuring the temporal and/or spatial variations in the intracellular free calcium concentration ([Ca 2+ ] i ) is a common theme in cytometry, cell biology, and neuroscience. Following the seminal work by Tsien and co-workers in the early 1980s, , a whole family of fluorescent indicators with different fluorescence properties and Ca 2+ -binding affinities has been generated. , These indicators have in common the principle of covalently linking an organic fluorophore to a Ca 2+ -chelating moiety, mostly to BAPTA. Ca 2+ binding rotates the carbon−nitrogen bond which diverts the nitrogen free electron pairs out of conjugation, resulting in modulating the fluorescence intensity and/or in spectral shifts.…”