Dye‐Sensitized Core/Shell Upconversion Nanoparticles for Detecting Nitrites in Plant Cells

Abstract

A fluorescent nanoprobe is reported for rapid detection of nitrites (NO2−) in plant cells. The probe is fabricated by linking neutral reds (NR) to the surface of upconversion fluorescent core/shell nanocrystalline with the bridging of polyethylene glycol (PEG) molecules. The fluorescence of upconversion nanoparticles (UCNPs) is stored by NR through fluorescence resonance energy transfer (FRET) under 980 nm excitation that can be released by further linking to NO2−. It is observed that the intensity rate of green to red emission of NR‐modified UCNPs changes linearly with increasing the amount of NO2−. So that concentration of NO2− can be accordingly addressed. Worth mentioning is that, comparing with bare core upconversion nanoparticles (NPs), core/shell UCNPs can greatly reduce the surface quenching of the fluorescence induced by solvents instead of NR and thus leading to the enhancement of signal‐to‐noise ratios. Moreover, excitation of core/shell UCNPs requires only a much lower power (0.06 W cm−2) than bare cores which is beneficial to reducing the decomposition of NR to stabilize the FRET processes. Under the optimum conditions, the detection limit of nitrite in plant cells was 0.1 µg mL−1.

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging

“…In other cases, the measured PL ratio is between the emission intensities of energy-transfer-quenched and -unquenched (or less quenched) UCNP emission bands. Recent examples have included methods for the detection of pH, , H 2 S (aq), NO (aq), , peroxynitrite, and nitrites …”

Fluorescent nanoparticles as tools in ecology and physiology

“…Imaging experiments with UCNPs have also been performed in small animals such as jellyfish and ants (Chen et al ., 2015 b ; Alkahtani et al ., 2017). UCNP‐based tools have been developed for sensing the spatiotemporal localisation of Zn ions in zebrafish during embryo development (Hu et al ., 2019) and for detection of nitrate (LOD 100 μg/l) in Chinese cabbage ( Brassica rapa ; Yang et al ., 2018 c ). Similarly, an aptamer sensor for the antibiotic chloramphenicol (LOD 0.01 μg/l; Wu et al ., 2015) has been developed for food safety purposes.…”