Water-Dispersible Activatable Nanoprobe for Detecting Cadmium-Ion-Induced Oxidative Stress in Edible Crops via Near-Infrared Second-Window Fluorescence Imaging

Abstract

Edible crops are important in terms of food security and sustainable agriculture. Heavy-metal-ion contamination of water/soil has deleterious impacts on the growth of edible crops. Among the heavy metals, cadmium (Cd) is toxic to plants, people, and animals, as it is widely used in industry; it has become the most important metal ion in the soil/water pollution. Once the toxic Cd ion enters edible crops via the water/soil in which the crops grow, it will induce oxidative stress (overproduction of reactive oxygen species with H2O2 being the most abundant) in the crops, and strong oxidative stress leads to the crops’ growth depression or inhibition. Hence, it is of great significance to accurately monitor the oxidative stress induced by Cd ions in edible crops, as the monitoring results could be employed for the early warning of Cd-ion pollution in water/soil. Herein, we design an activatable nanoprobe that can detect Cd-ion-induced oxidative stress in edible crops via near-infrared second-window (NIR-II) fluorescence imaging. The molecular probe IXD-B contains the diphenylamine-modified xanthene group acting as the electron-donating unit, bis­(methylenemalononitrile)­indan as the electron-accepting unit, and the methenephenylboronic acid group as the recognition moiety for H2O2 and the fluorescence quencher. The probe molecules being encapsulated by the amphiphilic DSPE-PEG2000 render the water-dispersible nanoprobe (IXD-B@DSPE-PEG2000). When the nanoprobe enters the edible crops, it can be activated by the overexpressed H2O2 therein and consequently emit strong NIR-II fluorescence signals for visualizing and tracking the oxidative stress in edible crops induced by Cd ions.

A near-infrared fluorescent probe for detection of H2S and its application in monitoring meat freshness and plant growth under aluminium-induced stress

“…Upon exposure to 10 mM aluminium ions, the intensity of fluorescence signals enhance; this is probably because the relatively high abiotic stress inhibits the growth, and in the meantime, it also stimulates the overproduction of H 2 S to fight against the stress, 29 hence the length of the seedlings shortens slightly and around 60% of germination percentage can still be observed. However, As the concentration of aluminium ions continues to increase to 25 mM, the intensity of fluorescence decreases obviously, which may be attributed to the serious stress leading to the decline of l -cysteine desulfhydrase activity 28,30 and consequently H 2 S is underproduced in vivo in the plants that can barely fight against the stress, therefore both the length of the seedlings and the germination percentage decline obviously. Taken together, these experiments demonstrate that the probe CHO–OH–NO 2 could be employed for monitoring aluminium ion-induced stress in the early germination of wheat grains.…”

Renal-Clearable Probe with Water Solubility and Photostability for Biomarker-Activatable Detection of Acute Kidney Injuries via NIR-II Fluorescence and Optoacoustic Imaging

“…Fluorescence imaging in the near-infrared second window (NIR-II, 900–1700 nm emission) has innate advantages of weak scattering of light and little autofluorescence in tissues, thus allowing imaging of organisms in a real-time way with higher resolution and at greater depth, facilitating more accurate disease diagnosis, and understanding of disease progression. − An optoacoustic (photoacoustic) imaging method images a sample with large penetration depth and high resolution by collecting ultrasound waves produced by photoabsorbers in the sample. − Especially, multispectral optoacoustic tomography (MSOT) is more advantageous, since this imaging technique detects the ultrasound signals produced by various photoabsorbers in the sample by irradiating the sample with laser light of multiple wavelengths; and the determination of the spectral identity of each photoabsorber is achieved by spectral unmixing so that the optoacoustic signal of a specific photoabsorber can be tracked. In addition, 3D (three-dimensional) images can be easily acquired or generated, thus facilitating accurate localization of the disease site and assessment of its size. − A probe suitable for NIR-II fluorescent and optoacoustic dual-mode imaging is very advantageous as it can provide mutually corroborating information.…”