Kidney-Targeted Near-Infrared Fluorescence Probe Reveals That SO2 Is a Biomarker for Cisplatin-Induced Acute Kidney Injury

Rational design of an ultrabright quinolinium-fused rhodamine turn-on fluorescent probe for highly sensitive detection of SO2 derivatives: Applications in food safety and bioimaging

Sulfur dioxide (SO2) is an essential signaling molecule involved in various physiological processes within living organisms. Bisulfite (HSO3-) possesses antioxidant, antimicrobial, and preservative properties, making it a common food additive. However, elevated levels of SO2 or excessive HSO3- intake can lead to a range of diseases, highlighting the importance of detecting SO2 and its derivatives (HSO3-/SO32-). This study presents a quinolinium-fused rhodamine fluorogenic probe (RQB-R) for ultrafast, highly selective, and sensitive detection of HSO3-. The probe operates via a dual-response mechanism, exhibiting a visible color change and a transition from nonemissive to intense red fluorescence upon interaction with HSO3-. The detection mechanism involves a 1,4-nucleophilic addition reaction of HSO3- at the 4-position of the quinolinium unit, which bypasses the photoinduced electron-transfer fluorescence quenching pathway and activates the intramolecular charge transfer mechanism, thereby enhancing fluorescence emission. Practical applications of the RQB-R probe include rapid quantification of HSO3- levels in sugar samples and integration into smartphone-assisted detection platforms. This method demonstrates excellent biocompatibility and enables visualization of both exogenous and endogenous HSO3- within MCF-7 cells, with a specific focus on targeting mitochondria.

A novel fluorescent probe for fast detection of sulfur dioxide derivatives in water, soil, food samples and its applications in biological imaging

Sulfur dioxide (SO2) has a wide range of applications in food additives and industrial production, and it is one of the main substances that form acid rain, causing serious harm to ecosystems and human health. Hence, it is necessary to construct an effective tool to quickly and accurately detect SO2 derivatives in environmental, food, and biological samples. In this study, fluorescent probe NPMQ was built to detect SO2 derivatives from nopinone with the merits of superior water solubility, high sensitivity (12 nM), excellent specificity, large Stokes shift (180 nm), and rapid response time (within 5 s). NPMQ was used to qualitatively and quantitatively detect SO2 derivatives in environmental water, soil and food samples. In addition, an electrospinning film was prepared with the probe NPMQ to image SO2 derivatives, and test strips are capable of rapidly, sensitively, and selectively detecting SO2 derivatives with the naked eye. Moreover, the probe NPMQ was used to visualize endogenous SO2 derivatives in Arabidopsis thaliana under Cd2+ stress. Furthermore, the probe NPMQ was employed to image exogenous and endogenous SO2 derivatives in living Hela, HepG-2 cells, and zebrafish. This study develops an effective tool for monitoring SO2 derivatives in the environmental, food, and biological systems.

Purification-free synthesis of bright lactoglobulin@dye nanoprobe for second near-infrared fluorescence imaging of kidney dysfunction in vivo

Kidney disease is currently prevalent worldwide but only shows insidious symptoms in the early stages. The second near-infrared window (NIR-II) fluorescence imaging has become a widely used preclinical technology for evaluating renal dysfunction due to its high resolution and sensitivity. However, bright renal clearable NIR-II fluorescence nanoprobes with a simple synthesis process are still lacking. Herein, we develop a lactoglobulin (LG)@dye nanoprobe for NIR-II fluorescence imaging of kidney dysfunction in vivo based on a purification-free method. The nanoprobe was synthesized by simply mixing LG and IR820 in aqueous solutions at 70 °C for 2 h based on the covalent interaction between the meso-Cl in IR820 and LG. The synthesized LG@IR820 nanoprobe has bright and stable NIR-II fluorescence, ultra-small size (<5 nm), low toxicity, and renal-clearable ability. The high reaction efficiency and pure aqueous reaction media make the synthesis method purification-free. In a unilateral ureteral obstruction mouse model, incipient renal dysfunction assessment was achieved by LG@IR820 nanoprobe, which couldn't be diagnosed with conventional kidney function indicators. This study provides a bright and purification-free NIR-II LG@IR820 nanoprobe to visualize kidney dysfunction at the early stage.

Advances in fluorescent probe development for bioimaging of potential Parkinson's biomarkers

Parkinson's disease (PD) is a common neurodegenerative disease. The clinical symptoms of PD are usually related to motor symptoms, including postural instability, rigidity, bradykinesia, and resting tremors. At present, the pathology of PD is not yet clear. Therefore, revealing the underlying pathological mechanism of PD is of great significance. A variety of bioactive molecules are produced during the onset of Parkinson's, and these bioactive molecules may be a key factor in the development of Parkinson's. The emerging fluorescence imaging technology has good sensitivity and high signal-to-noise ratio, making it possible to deeply understand the pathogenesis of PD through these bioactive molecules. Currently, fluorescent probes targeting PD biomarkers are widely developed and applied. This article categorizes and summarizes fluorescent probes based on different PD biomarkers, systematically introduces their applications in the pathological process of PD, and finally briefly elaborates on the challenges and prospects of these probes. We hope that this review will provide in-depth reference insights for designing fluorescent probes, and contribute to study of the pathogenesis and clinical treatment of PD.

Noninvasive Diagnosis of Kidney Dysfunction Using a Small-Molecule Manganese-Based Magnetic Resonance Imaging Probe

Contrast-enhanced magnetic resonance imaging (CE-MRI) is a promising approach for the diagnosis of kidney diseases. However, safety concerns, including nephrogenic systemic fibrosis, limit the administration of gadolinium (Gd)-based contrast agents (GBCAs) in patients who suffer from renal impairment. Meanwhile, nanomaterials meet biosafety concerns because of their long-term retention in the body. Herein, we propose a small-molecule manganese-based imaging probe Mn-PhDTA as an alternative to GBCAs to assess renal insufficiency for the first time. Mn-PhDTA was synthesized via a simple three-step reaction with a total yield of up to 33.6%, and a gram-scale synthesis can be realized. Mn-PhDTA has an r1 relaxivity of 2.72 mM-1 s-1 at 3.0 T and superior kinetic inertness over Gd-DTPA and Mn-EDTA with a dissociation time of 60 min in the presence of excess Zn2+. In vivo and in vitro experiments demonstrate their good stability and biocompatibility. In the unilateral ureteral obstruction rats, Mn-PhDTA provided significant MR signal enhancement, enabled distinguishing structure changes between the normal and damaged kidneys, and evaluated the renal function at different injured stages. Mn-PhDTA could act as a potential MRI contrast agent candidate for the replacement of GBCAs in the early detection of kidney dysfunction and analysis of kidney disease progression.