A Turn-On Luminescence Method for Phosphate Determination Based on Fast Green-Functionalized ZrO₂:Yb,Er@ZrO₂ Core@Shell Upconversion Nanoparticles

Abstract

The development of practical and sensitive tools for detecting phosphate deficiency could facilitate engineering approaches to enhance crop yield and quality in phosphate-stressed environments, reducing the misuse of nonrenewable fertilizers and their consequent ecological impact. Herein, a 975 nm-activated method based on ZrO2:Yb,Er@ZrO2 core@shell upconversion nanoparticles is presented for rapid visualization and determination of the phosphate ions in aqueous solutions and extracts. At optimized thickness, the nondoped ZrO2 shell not only enhances the emission of the ZrO2:Yb,Er but also provides an active surface for the intense interaction with the phosphate group, allowing a “label-free” determination that avoids the use of additional phosphate-recognizing elements like ligands or antibodies. According to the experimental evidence, the optical output of the ZrO2:Yb,Er@ZrO2 nanoparticles specifically matches with the absorption spectrum of the fast green alimentary dye (FG) electrostatically attached to the nanoparticle surface, activating the Förster resonance energy transfer (FRET) and thereby the upconversion luminescence quenching. Upon addition of the phosphate ions and the covalent interaction with the ZrO2:Yb,Er@ZrO2–FG nanocomplex, the FG is gradually removed, displaying a fast and reproducible “turn-on” luminescence which allows measurements in a few minutes. This rapid response is due to the stronger coordination between the ZrO2 shell and the phosphate compared to the FG molecules (−31.97 and −5.99 eV, respectively). The detection method was then effectively modulated in a 20–1000 nM linear response range without interfering effects of commonly coexisting ions, achieving a detection limit up to 15 times lower than that obtained with the conventionally used colorimetric methods.

Adsorption of PET on concrete nano-structures: an in-silico assay

“…The concrete and the PET molecules were modeled using the Avogadro package [10] and optimized through the PBE [11] functional using the SIESTA software. [12] Finally, the composite was modeled and optimized at the same level as their components and based on the methodology performed by some of us [13]. The molecules were visualized using the Jmol software.…”

A Comprehensive Review on Upconversion Nanomaterials-Based Fluorescent Sensor for Environment, Biology, Food and Medicine Applications

“…Phosphorus is required for plants growing. Ramirez-Garcia et al [ 109 ] designed a nano-scale conjugated fluorescence sensor. The sensor uses conjugated luminescence of Fast Green alimentary dye (FG) and ZrO 2 : Yb, Er@ZrO 2 , as well as the strong interaction and spontaneous formation of chemical bonds between phosphate group and zirconia (ZrO 2 ) as a phosphate monitor in the environment, as shown in Figure 5 B.…”

“…( B ) Schematic illustration of the phosphate determination method based on FRET from ZrO 2 : Yb, Er@ZrO 2 core@shell nanoparticles to the FG acceptor. Reprinted with permission from [ 104 , 109 ]. Copyright 2017, Elsevier and 2019, American Chemical Society.…”

Electronic Excitation Characteristics and Spectral Behavior of Phosphate Anions

“…Phosphorus is the key nutrient for organism development in the ecosystem, and phosphorus-rich products are commonly produced and used in the industry, agriculture, and daily life. , Phosphorus is also considered as the main limiting factor of water eutrophication. , The excessive discharge of phosphate into water leads to massive algae proliferation, water quality deterioration, and even collapse of the aquatic ecosystem. , Therefore, a real-time monitoring method is needed to be developed to determine the concentration of phosphorus in water.…”