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Nanomaterials 2019, 9(2), 245; https://doi.org/10.3390/nano9020245

Biosynthesized Highly Stable Au/C Nanodots: Ideal Probes for the Selective and Sensitive Detection of Hg2+ Ions

1
Department of Nanochemistry, Gachon University, Gyeonggi-do 13120, Korea
2
Department of Bionanotechnology, Gachon University, Gyeonggi-do 13120, Korea
3
School of Integrative Engineering, Chung-Ang University, Seoul 06974, Korea
4
Department of Chemical and Biological Engineering, Gachon University, 1342 Seongnam Daero, Seongnam-Si, Gyeonggi-do 13120, Korea
*
Authors to whom correspondence should be addressed.
The authors are equally contributed.
Received: 23 January 2019 / Revised: 3 February 2019 / Accepted: 7 February 2019 / Published: 12 February 2019
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Abstract

The enormous ongoing industrial development has caused serious water pollution which has become a major crisis, particularly in developing countries. Among the various water pollutants, non-biodegradable heavy metal ions are the most prevalent. Thus, trace-level detection of these metal ions using a simple technique is essential. To address this issue, we have developed a fluorescent probe of Au/C nanodots (GCNDs-gold carbon nanodots) using an eco-friendly method based on an extract from waste onion leaves (Allium cepa-red onions). The leaves are rich in many flavonoids, playing a vital role in the formation of GCNDs. Transmission electron microscopy (TEM) and Scanning transmission electron microscopy-Energy-dispersive X-ray spectroscopy (STEM-EDS) elemental mapping clearly indicated that the newly synthesized materials are approximately 2 nm in size. The resulting GCNDs exhibited a strong orange fluorescence with excitation at 380 nm and emission at 610 nm. The GCNDs were applied as a fluorescent probe for the detection of Hg2+ ions. They can detect ultra-trace concentrations of Hg2+ with a detection limit of 1.3 nM. The X-ray photoelectron spectroscopy results facilitated the identification of a clear detection mechanism. We also used the new probe on a real river water sample. The newly developed sensor is highly stable with a strong fluorescent property and can be used for various applications such as in catalysis and biomedicine. View Full-Text
Keywords: onion leaves; GCNDs; orange fluorescent; TEM; mercury ion sensor onion leaves; GCNDs; orange fluorescent; TEM; mercury ion sensor
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Venkateswarlu, S.; Govindaraju, S.; Sangubotla, R.; Kim, J.; Lee, M.-H.; Yun, K. Biosynthesized Highly Stable Au/C Nanodots: Ideal Probes for the Selective and Sensitive Detection of Hg2+ Ions. Nanomaterials 2019, 9, 245.

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