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Open AccessArticle

In-Situ Gold–Ceria Nanoparticles: Superior Optical Fluorescence Quenching Sensor for Dissolved Oxygen

by Nader Shehata 1,2,3,4,5,*, Ishac Kandas 1,2,4 and Effat Samir 6
1
Center of Smart Nanotechnology and Photonics (CSNP), SmartCI Research Center, Alexandria University, 21544 Alexandria, Egypt
2
Department of Engineering Mathematics and Physics, Faculty of Engineering, Alexandria University, 21544 Alexandria, Egypt
3
USTAR Bio-innovation center, Utah State University, Logan, Utah 84341, USA
4
Kuwait College of Science and Technology, Doha Area, 7th Ring Road, Safat 13133, Kuwait
5
The Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA
6
Department of Electrical Engineering, Old Dominion University, Norfolk, VA 23508, USA
*
Author to whom correspondence should be addressed.
Nanomaterials 2020, 10(2), 314; https://doi.org/10.3390/nano10020314
Received: 11 December 2019 / Revised: 30 December 2019 / Accepted: 3 January 2020 / Published: 12 February 2020
Cerium oxide (ceria) nanoparticles (NPs) have been proved to be an efficient optical fluorescent material through generating visible emission (~530 nm) under violet excitation. This feature allowed ceria NPs to be used as an optical sensor via the fluorescence quenching Technique. In this paper, the impact of in-situ embedded gold nanoparticles (Au NPs) inside ceria nanoparticles was studied. Then, gold–ceria NPs were used for sensing dissolved oxygen (DO) in aqueous media. It was observed that both fluorescence intensity and lifetime were changed due to increased concentration of DO. Added gold was found to enhance the sensitivity of ceria to DO quencher detection. This enhancement was due to optical coupling between the fluorescence emission spectrum of ceria with the surface plasmonic resonance of gold nanoparticles. In addition, gold caused the decrease of ceria nanoparticles’ bandgap, which indicates the formation of more oxygen vacancies inside the non-stoichiometric crystalline structure of ceria. The Stern–Volmer constant, which indicates the sensitivity of optical sensing material, of ceria–gold NPs with added DO was found to be 893.7 M−1, compared to 184.6 M−1 to in case of ceria nanoparticles only, which indicates a superior optical sensitivity to DO compared to other optical sensing materials used in the literature to detect DO. Moreover, the fluorescence lifetime was found to be changed according to the variation of added DO concentration. The optically-sensitivity-enhanced ceria nanoparticles due to embedded gold nanoparticles can be a promising sensing host for dissolved oxygen in a wide variety of applications including biomedicine and water quality monitoring.
Keywords: ceria; dissolved oxygen; gold nanoparticles; sensing; fluorescence quenching ceria; dissolved oxygen; gold nanoparticles; sensing; fluorescence quenching
MDPI and ACS Style

Shehata, N.; Kandas, I.; Samir, E. In-Situ Gold–Ceria Nanoparticles: Superior Optical Fluorescence Quenching Sensor for Dissolved Oxygen. Nanomaterials 2020, 10, 314.

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