Next Article in Journal
Recovery of Li(Ni0.33Mn0.33Co0.33)O2 from Lithium-Ion Battery Cathodes: Aspects of Degradation
Next Article in Special Issue
Preparation of N-Doped Carbon Nanosheets from Sewage Sludge for Adsorption Studies of Cr(VI) from Aqueous Solution
Previous Article in Journal
Strain-Tunable Visible-Light-Responsive Photocatalytic Properties of Two-Dimensional CdS/g-C3N4: A Hybrid Density Functional Study
Previous Article in Special Issue
Facile Electrochemical Sensor for Nanomolar Rutin Detection Based on Magnetite Nanoparticles and Reduced Graphene Oxide Decorated Electrode
Article Menu
Issue 2 (February) cover image

Export Article

Open AccessArticle
Nanomaterials 2019, 9(2), 245;

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

Department of Nanochemistry, Gachon University, Gyeonggi-do 13120, Korea
Department of Bionanotechnology, Gachon University, Gyeonggi-do 13120, Korea
School of Integrative Engineering, Chung-Ang University, Seoul 06974, Korea
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
Full-Text   |   PDF [4878 KB, uploaded 12 February 2019]   |  
  |   Review Reports


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

Graphical abstract

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).

Supplementary material


Share & Cite This Article

MDPI and ACS Style

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.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Nanomaterials EISSN 2079-4991 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top