Novel Fluorescent Sensor Revolutionizes Detection of Permanganate Ions in Water

According to a recent study, a new fluorescent sensor demonstrated improved sensitivity and accuracy in detecting permanganate ions in water (1). Permanganate in water is an environmental concern due to its strong oxidizing properties. This oxidizing capacity can harm aquatic life and alter water chemistry, leading to potential toxicity, and the formation of harmful chemical by-products, all of which complicate drinking water treatment processes.

Fluorescence sensing has emerged as the method of choice for detecting and analyzing ions because of its sensitivity and specificity. When done correctly, fluorescence sensing quantifies information about the specific target analyte under study (2). It accomplishes this by examining the fluorescence intensity and noting any changes in fluorescence excitation and emission wavelengths (2). This process provides valuable information about the sample's composition, concentration, and chemical interactions.

A recent study led by Yang Zhang and Wen-Kui Dong from Lanzhou Jiaotong University used fluorescence sensing to detect permanganate ions in water. To learn more about the permanganate ions in water, the research team developed and tested a new fluorescent sensor. The symmetrically double-armed salamo type fluorescent sensor, termed BMS (benzimidazole sensor) and incorporating benzimidazole units, marks a significant advancement in detecting MnO₄^– in aqueous environments (1).

Clear Water drop with circular waves | Image Credit: © willyam - stock.adobe.com

This new BMS fluorescence sensor, was found to be responsive to MnO₄^–, showing great specificity within a DMSO:H₂O medium (1). The sensor, in particular, performed well in Tris-HCl buffer at pH 7.2 (1). The sensor facilitated dual-channel detection of MnO₄^– through fluorescent and colorimetric changes, offering a comprehensive approach to sensing this critical analyte (1).

Read More: Novel Fluorescent Sensor for Mesotrione Detection

During the study, the research team examined several experimental parameters. The researchers looked at limit of detection (LOD) and limit of quantification (LOQ) thresholds (1). They also calculated the binding affinity constants (Ka) using advanced analytical tools (1). Using spectroscopic techniques, the research team determined the interaction mechanism between the BMS sensor and MnO₄^–. To determine this, the research team deployed electrospray ionization mass spectrometry (ESI-MS), ultraviolet-visible (UV-vis) spectroscopy, infrared (IR) spectroscopy, Stern-Volmer plots, and conducted density functional theory (DFT) computations (1).

Through fluorescence titration, the study reveals that BMS, incorporating a benzimidazole moiety known for its luminescent properties, exhibited significant fluorescence intensity, which was notably quenched upon the addition of MnO₄^– (1). This quenching effect, attributed to both static and dynamic mechanisms, was further elucidated through comprehensive analysis (1).

Read More: Histamine Determined Using Fluorescence Detection System

The researchers also made notes in their study regarding dynamic quenching. For example, dynamic quenching only occurred at lower MnO₄^– concentrations because of collision-induced energy transfer (1). However, at higher concentrations, the formation of a non-fluorescent complex [BMS(MnO₄)]^– through likely hydrogen bonding indicated static quenching (1).

By testing the BMS sensor in real water samples, the researchers demonstrated the applicability of the sensor in real-world scenarios. Notably, BMS was fabricated into test strips, offering a simple yet effective method for the selective detection of MnO₄^– (1).

In conclusion, the researchers were able to demonstrate by developing this symmetrical double-armed salamo type fluorescent sensor. As a result, the BMS sensor represents an advancement in fluorescence sensing. Its high sensitivity, selectivity, and practical applicability underscore its potential for widespread use in environmental monitoring and analytical chemistry (1).

References

(1) Yuan, P.-L.; Tong, L.; Li, X.-X.; et al. A Benzimidazole-Appended Double-Armed Salamo Type Fluorescence and Colorimetric Bifunctional Sensor for Identification of MnO4− and its Applications in Actual Water Samples. Spectrochim Acta A Mol Biomol Spectrosc. 2024, 315, 124252. DOI: 10.1016/j.saa.2024.124252

(2) Yuan, Y. Jia, H.; Xu, D.; et al. Novel Method in Emerging Environmental Contaminants Detection: Fiber Optic Sensors Based on Microfluidic Chips. Sci. Total Environ. 2023, 857, 159563. DOI: 10.1016/j.scitotenv.2022.159563