A simple benzothiazolium-based sensor for cyanide detection: Applications in environmental analysis and bioimaging

Sisay Uota; Bor-Jang Hwang; Raymond Butcher; Roger Mullins; James Wachira; Yousef Hijji; Fasil Abebe

doi:10.1016/j.saa.2024.125155

A simple benzothiazolium-based sensor for cyanide detection: Applications in environmental analysis and bioimaging

Spectrochim Acta A Mol Biomol Spectrosc. 2025 Feb 5:326:125155. doi: 10.1016/j.saa.2024.125155. Epub 2024 Sep 21.

Authors

Sisay Uota¹, Bor-Jang Hwang², Raymond Butcher³, Roger Mullins⁴, James Wachira⁵, Yousef Hijji⁶, Fasil Abebe⁷

Affiliations

¹ Department of Chemistry, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA.
² Department of Biology, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA.
³ Department of Chemistry, Howard University, 626 College Street NW, Washington DC 20059 USA.
⁴ ASCEND Center for Biomedical Research, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA; Center for Urban Health Disparities Research and Innovation, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA.
⁵ ASCEND Center for Biomedical Research, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA; Center for Urban Health Disparities Research and Innovation, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA; Department of Biology, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA.
⁶ Department of Chemistry, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA; Department of Chemistry, Howard University, 626 College Street NW, Washington DC 20059 USA.
⁷ Department of Chemistry, Morgan State University, 1700 E Cold Spring Ln, Baltimore, MD 21251 USA. Electronic address: [email protected].

PMID: 39357252
DOI: 10.1016/j.saa.2024.125155

Abstract

A new sensor based on Ethylbenzothiazolium-2-hydroxynaphthaldehyde conjugate-based fluorescent sensor, (E)-3-ethyl-2-(2-(2-hydroxynaphthalen-1-yl) vinyl) benzo[d]thiazol-3-ium iodide (SU-1) was designed and synthesized. The structure of SU-1 was confirmed by ¹H NMR, ¹³C NMR, HRMS, and single crystal XRD spectral analysis. SU-1 displayed a colorimetric and fluorometric response in a DMSO:H₂O (1:1,v/v) matrix, changing color from pale yellow to colorless visible to the naked eye, accompanied by a ∼ 120 nm red-shift in the absorption spectra upon CN^- addition. This shift, due to formation of deprotonation followed by the nucleophilic attack on the benzothiazolium ring's double bond, disrupts π-conjugation, blocking intramolecular charge transfer within SU-1. However, competitive anions showed negligible interference while detecting CN^-. The Limit of detection for CN^- was determined to be 0.27 nM, significantly below the WHO's permissible CN^- concentration in drinking water (1.9 μM). Job's plot analysis shows that the binding stoichiometry of SU-1 to CN^- is a 1:1, with a stability constant (Ka) of 1.58 x 10⁴ M^-1. The sensor demonstrated practical applications in environmental water samples and fluorescence imaging of intracellular CN^- in CAD cell line.

Keywords: Benzothiazolium salts; Bioimaging; Colorimetric; Cyanide ion; Sensor.

MeSH terms

Benzothiazoles* / chemistry
Colorimetry / methods
Cyanides* / analysis
Environmental Monitoring / methods
Fluorescent Dyes* / chemical synthesis
Fluorescent Dyes* / chemistry
Humans
Limit of Detection
Spectrometry, Fluorescence

Substances

Benzothiazoles
Cyanides
Fluorescent Dyes