Ratiometric fluorometric determination of silver(I) by using blue-emitting silicon- and nitrogen-doped carbon quantum do
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ORIGINAL PAPER
Ratiometric fluorometric determination of silver(I) by using blue-emitting silicon- and nitrogen-doped carbon quantum dots and red-emitting N-acetyl-L-cysteine-capped CdTe quantum dots Huifang Wu 1 & Changlun Tong 1 Received: 28 April 2019 / Accepted: 12 September 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract A ratiometric fluorometric assay for silver(I) is described. The method makes use of a dually emitting quantum dot hybrid, which is composed of (a) blue-fluorescent silicon- and nitrogen-doped carbon quantum dots (CQDs), and (b) of red-emitting CdTe quantum dots (QDs) capped with N-acetyl-L-cysteine. The red-emitting CdTe QDs undergo strong and specific quenching by Ag(I), whereas the blue-emitting N,Si-CQDs are not quenched. The two kinds of QDs are mixed and used as a ratiometric fluorescent probe. A linear relationship is found between the log of intensities [(I608/I441)0/(I608/I441)] and the concentration of Ag(I) in the range from 5.0–1000 nM, and the limit of detection (at S/N = 3) is 1.7 nM. Possible interferents (including 17 general metal ions, 12 anions and fulvic acid) do not interfere with the determination. The assay was successfully used for the determination of Ag(I) in surface water and wastewater samples. The fluorescence quenching mechanism of the ratiometric assay system was also discussed in detailed. Keywords Silver ions . Silicon-doped carbon dots . Nitrogen-doped carbon dots . Surface water . Wastewaters . Quenching efficiency . Fluorescentprobe . 3-Aminopropyltriethoxysilane functionalized carbon dots . Fluorescence quenching mechanism . Dual-emission quantum dots hybrid
Introduction Silver, as one of precious heavy metal and highly demanded cost-effective metal catalyst, possesses wide applications in many fields such as photography, electronics, optics, medicine and pharmacy [1, 2]. Ag+ ions from industrial wastes had been admitted as poisonous metal pollutants in environmental media including ambient air, water, soil and even food [3]. They have highly toxic to many environmentally benign bacteria attributed to its antibacterial activity [4]. They also can inactivate sulfhydryl enzymes, combine with imidazole, amine and carboxyl groups of different metabolites, and then accumulate Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-019-3818-6) contains supplementary material, which is available to authorized users. * Changlun Tong [email protected] 1
Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
in human body [5]. The U.S. EPA had reported that when its concentration higher than 1.6 nM, it was toxic to microorganism even fishes, and the maximum permission concentration for total silver ions in drinking waters was 0.9 μM [6]. Therefore, it is very necessary to set up rapid, simple and efficient methods for highly selective and sensitive determination of A
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