A new AIEE-active carbazole based colorimetric/fluorimetric chemosensor for ultra-rapid and nano-level determination of Hg2+ and Al3+ in food/environmental samples and living cells

A new simple carbazole Schiff base (CBS) with typical aggregation-induced emission enhancement (AIEE) property was designed and synthesized based on carbaldehyde and 2-hydroxybenzohydrazide units, which was successfully utilized as a new dual-responsive colorimetric/fluorimetric chemosensor for highly selective and sensitive turn-off' fluorescence detection of Hg2+ and turn-on fluorescence sensing Al3+ in near-perfect aqueous media based on metal chelation mechanism. The low detection limits of CBS for Hg2+ and Al3+ were respectively determined to be 14.7 nM and 47.2 nM, far lower than the WHO guidelines for drinking water, which permitted its nano-level determination in real samples. The CBS for Hg2+/Al3+ sensing displayed outstanding advantages of pH stability, excellent reversibility, ultra-fast response, stronger anti-interference capability and lower cytotoxicity compared with other related chemosensors. The binding mode of CBS with Hg2+/Al3+ was determined to be a 1:1 complexation stoichiometry using Job's plot analysis and fluorescent titration curve, which further confirmed by FTIR and H-1 NMR analysis. Due to its good colorimetric/fluorimetric properties, a simple cost-effective portable on-site test strip was developed that allows for visual, fast, reliable and convenient detecting Hg2+/Al3+ in environmental analysis. Moreover, chemosensor CBS has successful application in building molecular logic gates. Furthermore, the CBS was successfully applied in soil, environmental water, and food samples analysis and live-cell imaging, demonstrated its great potentials in environmental and biological applications.

Automated summary

The newly designed CBS serves as a colorimetric/fluorimetric chemosensor for selective and sensitive detection of Hg2+ and Al3+ in aqueous media, with low detection limits and potential applications in environmental and biological fields.