Fluorescein Derivatives as Fluorescent Probes for pH Monitoring along Recent Biological Applications.

Florent Le Guern,Vanessa Mussard,Martin Rottman,Anne Gaucher,Damien Prim

doi:10.3390/ijms21239217

Abstract

Potential of hydrogen (pH) is one of the most relevant parameters characterizing aqueous solutions. In biology, pH is intrinsically linked to cellular life since all metabolic pathways are implicated into ionic flows. In that way, determination of local pH offers a unique and major opportunity to increase our understanding of biological systems. Whereas the most common technique to obtain these data in analytical chemistry is to directly measure potential between two electrodes, in biological systems, this information has to be recovered in-situ without any physical interaction. Based on their non-invasive optical properties, fluorescent pH-sensitive probe are pertinent tools to develop. One of the most notorious pH-sensitive probes is fluorescein. In addition to excellent photophysical properties, this fluorophore presents a pH-sensitivity around neutral and physiologic domains. This review intends to shed new light on the recent use of fluorescein as pH-sensitive probes for biological applications, including targeted probes for specific imaging, flexible monitoring of bacterial growth, and biomedical applications.

Highlights

In chemistry, potential of hydrogen, or Potential of hydrogen (pH), is a data describing the acidity or the basicity of a medium [1]
As acidic or basic compounds are continuously released as outputs of cellular life, pH monitoring offered a unique opportunity to acquired data from biologic systems [7]
The relevance of pH in biological systems can be observed at different scales: the pH of biological fluids is well described and its regulation essential to the proper function of organs, since abnormal values are both the sign and cause of disease developments. pH regulation within biological systems relies on a sensitive equilibrium, called pH homeostasis

Summary

Introduction

Potential of hydrogen, or pH, is a data describing the acidity or the basicity of a medium [1]. The fluorescent emission from this probe progressively decreases under intense light irradiations, which is an issue since pH monitoring is based on this intensity, and repeated measurements cause the signal to fade. Because of this photobleaching, all fluorescein derivatives must be stored in the dark, and experiments using this probe have to occur quickly. Irradiations, which is an issue since pH monitoring is based on this intensity, and repeated measurements cause the signal to fade

Molecular pH Sensor

Bacterial Growth

OOtthheerr AApppplliiccaattiioonns

Conclusions