"Turn-On" Fluorescent Biosensors for High Selective and Sensitive Detection of Al3+ Ion.

Pengfei Wang,Hui Li,Maroof Ahmad Khan,Fanda Meng,Lijie Liu

doi:10.3389/fchem.2020.607614

Pengfei Wang, Hui Li + Show 3 more

Open Access

https://doi.org/10.3389/fchem.2020.607614

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Abstract

A series of new compounds (1-4) based on pyrrole hydrazone Schiff bases were designed and synthesized. The interactions of these new compounds with metal ions and their fluorescent recognition were investigated. All compounds showed “turn-on” fluorescence in the presence of Al3+ in aqueous solution. Their sensing behaviors with Al3+ were studied using photophysical experiments, ESI-MS spectrometry analysis, 1H NMR titration, and DFT calculation. The detection limits of 1-4 for the analysis of Al3+ were found to reach a 10−8 M level in aqueous solution, which are far lower than the WHO guidelines for drinking water (7.41 mM for Al3+). A high selectivity test paper has been fabricated for Al3+ detection based on sensor 3. Theoretical calculations (DFT) have been carried out to elucidate the configuration of 1-4 and their Al complexes and rationalize experimental absorption data.

Highlights

Aluminum is widely used as a common metal, the content is second only to oxygen and silicon, ranking third, and is the most abundant metal element in the Earth’s crust (Das et al, 2013; Sahana et al, 2013)
We reported a series of chemosensors based on pyrrole hydrazone Schiff base derivatives (Scheme 1)
Due to the good conjugation in these molecules, the pyrrole ring, acylhydrazone, and benzene ring are almost on the same plane, which makes them have excellent planarity, and it is conducive to the intramolecular PET effect

Summary

INTRODUCTION

Aluminum is widely used as a common metal, the content is second only to oxygen and silicon, ranking third, and is the most abundant metal element in the Earth’s crust (Das et al, 2013; Sahana et al, 2013). The thiophene- and furan-hydrazide hydrazone Schiff bases have been used as fluorescent sensors for metal ions, anions, and organic acids (Boonkitpatarakul et al, 2015; Hwang et al, 2017; Jeong et al, 2017). We expect that the designed sensors 2-4 have more efficient and selective fluorescence recognition properties for Al3+ and have more responsive long-wave colors in the emission spectrum. After mixing for 1 min, fluorescence spectra were performed at room temperature. Solutions of various metal ions (4.5 μL, 20 mM, 30 equivalents) including Na+, K+, Ag+, Mg2+, Ca2+, Hg2+, Pb2+, Cd2+, Mn2+, Ni2+, Co2+, Cu2+, Zn2+, Fe2+, Fe3+, and Cr3+ were added to each sensor 1-4 solution (3 mL, 1 μM). (Na+, K+, Ag+, Mg2+, Ca2+, Hg2+, Pb2+, Cd2+, Mn2+, Ni2+, Co2+, Cu2+, Zn2+, Fe2+, Fe3+, and Cr3+) were added to each test paper

RESULTS AND DISCUSSION

CONCLUSIONS

DATA AVAILABILITY STATEMENT