Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis

This study presents a novel and sensitive method for the determination of glutathione (GSH), a crucial antioxidant and cellular protectant, using dual blue/orange-emitting carbon dots (BOCDs) and phenolphthalein (PHP). The sensing system operates at pH 9.0, exploiting the unique optical properties...

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Main Authors: Al-Montaser Bellah H. Ali, Ashraf M. Mahmoud, Yousef A. Bin Jardan, Aya M. Mostafa, James Barker, Mohamed M. El-Wekil
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Talanta Open
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666831925000219
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author Al-Montaser Bellah H. Ali
Ashraf M. Mahmoud
Yousef A. Bin Jardan
Aya M. Mostafa
James Barker
Mohamed M. El-Wekil
author_facet Al-Montaser Bellah H. Ali
Ashraf M. Mahmoud
Yousef A. Bin Jardan
Aya M. Mostafa
James Barker
Mohamed M. El-Wekil
author_sort Al-Montaser Bellah H. Ali
collection DOAJ
description This study presents a novel and sensitive method for the determination of glutathione (GSH), a crucial antioxidant and cellular protectant, using dual blue/orange-emitting carbon dots (BOCDs) and phenolphthalein (PHP). The sensing system operates at pH 9.0, exploiting the unique optical properties of BOCDs with emission peaks at 420 nm and 570 nm. In alkaline conditions, PHP develops a pink color that selectively quenches the 570 nm emission of the CDs while leaving the 420 nm peak unaffected. Upon introduction of GSH, the quinoid structure of PHP is converted to its benzenoid form via Michael addition, resulting in the disappearance of the pink color and subsequent restoration of the 570 nm fluorescence. This mechanism, utilized for the first time in GSH detection, offers a distinct advantage over previous methods that primarily relied on GSH's complexation capabilities. The analytical capabilities of the BOCDs/PHP ratiometric probe were extensively evaluated through multiple spectroscopic methods to understand its sensing mechanism. Performance analysis revealed impressive analytical figures of merit: the method exhibited strong linearity with a correlation coefficient of 0.9985, provided sensitive detection across a broad concentration range from 0.01 to 8.0 μM, and achieved a remarkably low detection limit of 3.33 nM. The method's versatility was enhanced through the development of a dual-mode smartphone platform, enabling both colorimetric and fluorometric GSH detection. Practical validation using human serum samples demonstrated the method's robustness in complex biological matrices, achieving high recovery rates between 98.5 % and 101.0 %, confirming its suitability for real-world clinical applications. This novel strategy combines the sensitivity of ratiometric fluorescence with the convenience of smartphone-based detection, offering a promising tool for GSH monitoring in clinical and research settings.
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spelling doaj-art-298cef446c29494ca2dab9de9f197c752025-02-07T04:48:26ZengElsevierTalanta Open2666-83192025-08-0111100418Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysisAl-Montaser Bellah H. Ali0Ashraf M. Mahmoud1Yousef A. Bin Jardan2Aya M. Mostafa3James Barker4Mohamed M. El-Wekil5Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt; Corresponding author.Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, EgyptDepartment of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, 11451, Saudi ArabiaDepartment of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, EgyptSchool of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston-upon-Thames, London KT1 2EE, UKDepartment of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, EgyptThis study presents a novel and sensitive method for the determination of glutathione (GSH), a crucial antioxidant and cellular protectant, using dual blue/orange-emitting carbon dots (BOCDs) and phenolphthalein (PHP). The sensing system operates at pH 9.0, exploiting the unique optical properties of BOCDs with emission peaks at 420 nm and 570 nm. In alkaline conditions, PHP develops a pink color that selectively quenches the 570 nm emission of the CDs while leaving the 420 nm peak unaffected. Upon introduction of GSH, the quinoid structure of PHP is converted to its benzenoid form via Michael addition, resulting in the disappearance of the pink color and subsequent restoration of the 570 nm fluorescence. This mechanism, utilized for the first time in GSH detection, offers a distinct advantage over previous methods that primarily relied on GSH's complexation capabilities. The analytical capabilities of the BOCDs/PHP ratiometric probe were extensively evaluated through multiple spectroscopic methods to understand its sensing mechanism. Performance analysis revealed impressive analytical figures of merit: the method exhibited strong linearity with a correlation coefficient of 0.9985, provided sensitive detection across a broad concentration range from 0.01 to 8.0 μM, and achieved a remarkably low detection limit of 3.33 nM. The method's versatility was enhanced through the development of a dual-mode smartphone platform, enabling both colorimetric and fluorometric GSH detection. Practical validation using human serum samples demonstrated the method's robustness in complex biological matrices, achieving high recovery rates between 98.5 % and 101.0 %, confirming its suitability for real-world clinical applications. This novel strategy combines the sensitivity of ratiometric fluorescence with the convenience of smartphone-based detection, offering a promising tool for GSH monitoring in clinical and research settings.http://www.sciencedirect.com/science/article/pii/S2666831925000219GlutathioneRatiometricDual emissionColorimetricSmartphone
spellingShingle Al-Montaser Bellah H. Ali
Ashraf M. Mahmoud
Yousef A. Bin Jardan
Aya M. Mostafa
James Barker
Mohamed M. El-Wekil
Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis
Talanta Open
Glutathione
Ratiometric
Dual emission
Colorimetric
Smartphone
title Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis
title_full Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis
title_fullStr Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis
title_full_unstemmed Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis
title_short Quinoid to benzenoid transition-driven glutathione sensing: Dual-emission carbon dots and smartphone-based ratiometric fluorescence analysis
title_sort quinoid to benzenoid transition driven glutathione sensing dual emission carbon dots and smartphone based ratiometric fluorescence analysis
topic Glutathione
Ratiometric
Dual emission
Colorimetric
Smartphone
url http://www.sciencedirect.com/science/article/pii/S2666831925000219
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