Acute kidney injuries (AKI) have serious short-term or long-term complications with high morbidity and mortality rate, thus posing great health threats. Developing high-performance NIR-II probes for noninvasive in situ detection of AKI via NIR-II fluorescent and optoacoustic dual-mode imaging is of great significance. Yet NIR-II chromophores often feature long conjugation and hydrophobicity, which prevent them from being renal clearable, thus limiting their applications in the detection and imaging of kidney diseases. To fully exploit the advantageous features of heptamethine cyanine dye, while overcoming its relatively poor photostability, and to strive to design a NIR-II probe for the detection and imaging of AKI with dual-mode imaging, herein, we have developed the probe PEG3-HC-PB, which is renal clearable, water soluble, and biomarker activatable and has good photostability. As for the probe, its fluorescence (900−1200 nm) is quenched due to the existence of the electron-pulling phenylboronic group (responsive element), and it exhibits weak absorption with a peak at 830 nm. Meanwhile, in the presence of the overexpressed H 2 O 2 in the renal region in the case of AKI, the phenylboronic group is converted to the phenylhydroxy group, which enhances NIR-II fluorescent emission (900−1200 nm) and absorption (600−900 nm) and eventually produces conspicuous optoacoustic signals and NIR-II fluorescent emission for imaging. This probe enables detection of contrast-agent-induced and ischemia/reperfusion-induced AKI in mice using real-time 3D-MSOT and NIR-II fluorescent dual-mode imaging via response to the biomarker H 2 O 2 . Hence, this probe can be used as a practicable tool for detecting AKI; additionally, its design strategy could provide insight into the design of other large-conjugation NIR-II probes with multifarious biological applications.
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.
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