Ultra-sensitive fluorene-based fluorescent sensors for Hg2+ detection using smartphone-assisted RGB analysis in water and food matrices


TÜMAY S. O., Duyar H., Sari E., Şenocak A., Köse B., Khataee A.

Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, cilt.350, 2026 (SCI-Expanded, Scopus) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 350
  • Basım Tarihi: 2026
  • Doi Numarası: 10.1016/j.saa.2025.127420
  • Dergi Adı: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Chemical Abstracts Core, Chimica, Compendex, INSPEC, MEDLINE
  • Anahtar Kelimeler: Fluorescence sensors, Hg2+ detection, Photo-induced electron transfer, Polystyrene thin film, Smartphone RGB analysis, Real sample
  • Atatürk Üniversitesi Adresli: Evet

Özet

Mercury is a highly toxic environmental pollutant due to its bioaccumulation, persistence, and severe neurotoxic effects on human health. In aquatic ecosystems, even trace levels of Hg2+ can undergo methylation to form methylmercury, a potent neurotoxin that enters the food chain through water and fish consumption. Developing straightforward, accessible, and reliable strategies for mercury detection remains essential. In this work, two fluorene-based Schiff base fluorescent sensors (2 and 3) were synthesized for highly selective detection of Hg2+. Upon interaction with Hg2+, both sensors showed a remarkable fluorescence enhancement, mainly due to the suppression of photo-induced electron transfer (PET) and the formation of rigid complexes that favor radiative emission. The 1:1 binding stoichiometry and sensing mechanism were confirmed by Job's plot, Benesi-Hildebrand analysis, Nuclear Magnetic Resonance (NMR) titration, Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS), lifetime measurements, and Density Functional Theory (DFT) calculations. Under optimized conditions (λex = 355/345 nm, pH 8.0), the sensors displayed wide linear ranges of 0.50–150.00 μM and 0.30–100.00 μM with low detection limits of 0.15 and 0.08 μM, respectively. Practical applicability was demonstrated through the determination of Hg2+ in environmental water and food samples, with recoveries ranging from 96.2 % to 100.6 % and no significant deviation from Inductively Coupled Plasma Mass Spectrometry (ICP-MS) (texp < tcritical). Moreover, polystyrene (PS) thin-film kits were developed for on-site analysis. These films, coupled with smartphone-based Red-Green-Blue (RGB) analysis, provided a reusable, robust alternative to paper-based tests. This dual-mode platform offers a practical route for portable and quantitative Hg2+ monitoring in environmental and food matrices.