Real-time sensitive detection of Cr (VI) in industrial wastewater and living cells using carbon dot decorated natural kyanite nanoparticles

This article reports a facile strategy to detect hexavalent chromium (Cr (VI)) using a naturally formed mineral (kyanite) based fluorometric sensor. Nitrogenous carbon dots have been incorporated into natural kyanite (KYCD) nanoparticles causing a stable bright blue fluorescence compared to its pristine counterpart. This sensing probe structurally stabilizes and resists the agglomeration of carbon dots, thus retaining fluorescence quality for a longer period. The promising bright blue fluorescence has been utilized further to detect Cr (VI) in wastewater and living cells. Ease of synthesis, low cost, and stability of the system offers the benefit for large-scale production, which is convenient for industrial production the sensing probe. The sensor shows high selectivity and sensitivity (LOD and LOQ of 0.11 mM and 0.36 mM respectively in case of linear fitting, whereas 0.26 mM and 0.88 mM respectively for full range plot) towards hexavalent chromium in presence of other interfering elements. A detailed study of photoinduced electron transfer (PET) mediated rapid 'turn off' sensing mechanism was carried out using Time-Dependent Density functional (TDDFT) calculations. The sensing efficacy of the probe remains unaltered under a wide range of pH and can be effective in various water types. Onsite sampling and probing of Cr (VI) in tannery wastewater has been performed to validate its real-life efficiency that yields excellent results. The sensor can effectively detect chromium at a cellular level (HeLa cells) in a similar way as the bright blue fluorescence diminishes in presence of the quenching ion. Experimental in vitro studies along with theoretical docking analysis has been conducted to substantiate such issues and a higher possibility of fluorophore binding was found for Isoleucine (2.9 A), Serine (2.96 A), and Glycine (3.16 A). This biocompatible sensor rapidly senses hexavalent chromium in living cells, which makes this efficient probe a true heavy metal-induced carcinogen sensor.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This article presents a facile strategy for detecting hexavalent chromium using a naturally formed mineral-based fluorometric sensor. The sensor shows stable bright blue fluorescence and can effectively detect hexavalent chromium in wastewater and living cells. It offers advantages such as ease of synthesis, low cost, and stability, making it suitable for large-scale production and industrial applications.