Chiral CQD-based PL and CD sensors for high sensitive and selective detection of heavy metal ions

摘要

Chiral biomas carbon quantum dots (CQDs) have attracted great interest because of their low cytotoxicity, low cost and facile synthesis, which are special useful for sensing. In this paper, CQDs derived from cane molasses were endowed chirality by a simple hydrothermal method with L-cysteine and D-cysteine as chiral sources respectively. The obtained chiral CQDs have significantly enhanced fluorescence properties, whose fluorescence intensity and fluorescence quantum yield are about 3 times of CQDs without chirality. A fluorescent sensor and a circular dichroic (CD) sensor were built and compared based on the fluorescence property and chirality of the obtained chiral CQDs, respectively, the former exhibits high selectivity and sensitivity for Ag+, while the latter exhibits high selectivity and sensitivity for Ag+, Hg2+and Cu2+ simultaneously. The detection mechanism of the CD sensor for metal ions was proposed based on the static quenching mechanism of the fluorescent sensor. The detection of real samples of tap water verified the reliability of the developed sensors. The present work expands the application field of CQDs.

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