Editorial Feature

Fluorescent Chloride Sensors

Article updated on 09/03/20 by Jo Finchen-Parsons


Image Credit: totojang1977/Shutterstock.com

A chloride ion sensor is a sensing element combined with a wireless embedded sensor platform to measure the concentration of chloride in a material.

Researchers at The Johns Hopkins University from Applied Physics Laboratory have developed a wireless chloride ion sensor.

The chloride ions are measured by a molecularly imprinted polymer membrane of polypyrrole and inter-digitated AgCl electrodes.

The chloride molecules penetrate the polymer membrane and get trapped. As a result, the electronic characteristics of the polymer are changed and a signal is produced with respect to the amount of chloride present.

The invention of chloride ions in physiological processes stimulates the measurements of intracellular chloride ions in live cells and the development of various fluorescent tools. Fluorescent chloride sensors offer a powerful tool for non-invasive monitoring of intracellular distribution and transmembrane fluxes.

Types of Fluorescent Chloride Sensors

Yellow Fluorescent Protein (YFP)-based Chloride Sensors

YFP-based sensors are mutated versions of a green fluorescent protein They contain four-point mutations and red-shifted excitation and emission spectra when compared to the green fluorescent protein.

YFP fluorescence senses various small anions resulting from ground-state binding near the chromophore. However, these sensors rather exhibit low kinetics of chloride association and dissociation.

Quinoline-based Chloride Sensors

These sensors are operated based on the capability of chloride molecules to quench the fluorescence of heterocyclic organic compounds with quaternary nitrogen. N-(6-methoxyquinolyl)-acetoethyl ester (MQAE), 6-methoxy-N-ethylquinolium Chloride– (MEQ), and 6-methoxy-1-(3-sulfonatopropyl) quinolinium (SPQ) are the most used quinolinium–based chloride–indicators.

Forster Resonance Energy Transfer (FRET)-based Chloride Sensors

These sensors consist of two fluorescent proteins such as cyan fluorescent protein (CFP) and yellow fluorescent protein combined with a polypeptide linker. The FRET-based chloride sensors allow ratiometric chloride measurements based on the chloride sensitivity of YFP and chloride insensitivity of CFP.

Image Credits: Photos.com.

Working Principle

According to Wang J. et al. (2012), the fluorescent chloride sensors are operated based on the principle that if a fluorescent indicator dye molecule binds the to-be-measured ion, the binding of the ion induces a structural change which changes the dye's fluorescent properties thereby changing the fluorescence light intensity.

The intensity of fluorescence light decreases when there is a higher concentration of chloride ions in the bound molecule.

The chloride concentration of material is quantitatively determined using the fluorescence intensity of MQAE, a chloride ion fluorescent indicator. The MQAE solution reacts with the chloride solution.

The solution mixture is then irradiated by UV light, and an optical detector is used to the fluorescence emission. The concentration of chloride ions in the solution is then calculated based on the Stern-Volmer equation.

Applications of Fluorescent Chloride Sensors

Fluorescent chloride sensors are used to measure chloride transport across cell membranes to regulate cell volume, resting potential, charge balance, and membrane excitability. They are also used for the diagnosis of cystic fibrosis.

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Kaur, Kalwinder. (2020, April 02). Fluorescent Chloride Sensors. AZoSensors. Retrieved on July 22, 2024 from https://www.azosensors.com/article.aspx?ArticleID=238.

  • MLA

    Kaur, Kalwinder. "Fluorescent Chloride Sensors". AZoSensors. 22 July 2024. <https://www.azosensors.com/article.aspx?ArticleID=238>.

  • Chicago

    Kaur, Kalwinder. "Fluorescent Chloride Sensors". AZoSensors. https://www.azosensors.com/article.aspx?ArticleID=238. (accessed July 22, 2024).

  • Harvard

    Kaur, Kalwinder. 2020. Fluorescent Chloride Sensors. AZoSensors, viewed 22 July 2024, https://www.azosensors.com/article.aspx?ArticleID=238.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Your comment type

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.