Plasmonic-Ceria Nanoparticles as Fluorescence Intensity and Lifetime Quenching Optical Sensor.

Nader Shehata,Effat Samir,Ishac Kandas

doi:10.3390/s18092818

Abstract

Ceria nanoparticles have been recently used as an optical fluorescent material with visible emission under ultraviolet excitation, due to the formation of trivalent cerium ions with corresponding oxygen vacancies. This paper introduces the enhancement of both fluorescence emission and lifetime through adding gold nanoparticles. The reason is due to possible coupling between the plasmonic resonance of gold nanoparticles and the fluorescence emission of ceria that has been achieved, along with enhanced formation of trivalent cerium ions. Both factors lead to higher fluorescence intensity peaks and shorter fluorescence lifetimes. As an application, gold-ceria nanoparticles have been used as an optical sensing material for lead particles in aqueous media based on fluorescence quenching. Stern-Volmer constant of in-situ gold-ceria nanoparticles is found to be 2.424 M−1, with a relative intensity change of up to 40% at 0.2 g/L.

Highlights

There are different fluorescent nanostructures which can be used as optical nanosensors based on fluorescence quenching mechanisms
The fluorescence emission of ceria nanoparticles has been improved by adding in-situ gold nanoparticles
Ceria nanoparticles with visible emission under ultraviolet excitation have been doped with gold nanoparticles which have a plasmonic resonance wavelength close to the peak fluorescence emission of ceria

Summary

Introduction

There are different fluorescent nanostructures which can be used as optical nanosensors based on fluorescence quenching mechanisms. One of the most efficient fluorescent nanostructures are cerium oxide (ceria) nanoparticles, based on their visible fluorescence emission under ultraviolet excitation in addition to their reduction-oxidation (redox) properties [1,2]. Ceria nanostructures can include oxygen vacancies which can be adsorption centers for some quenchers such as tiny metallic particles. The adsorbing centers inside ceria nanoparticles are found according to oxygen vacancies (O-vacancies) associated to the formed trivalent cerium ions inside the crystalline structures of non-stoichiometric ceria CeO2−x. It measures the time of the fluorophore, which here is trivalent cerium ion, in the excitation state before returning back to the ground state [8]. Fluorescence lifetime is another property affected by various parameters within ceria nanoparticles through different quenchers

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Discussion

Conclusion