A novel near-infrared fluorescent probe for butyrylcholinesterase: Research for screening of natural anti-AD inhibitors

Elevated levels of butyrylcholinesterase (BuChE) have the potential to be predictive in the timely detection and diagnosis of Alzheimer's disease (AD). By inhibiting of BuChE activity can raise acetylcholine levels and intervene AD processes. Therefore, BuChE as an important factor in treatment AD has been given more and more attention in clinical studies. Given the facts above, in this study, for precise monitoring of BuChE level changes and screening for possible butyrylcholinesterase inhibitor (BuChEI) for AD diagnosis and therapy, a near-infrared (NIR) fluorescence probe (NFP-BuChE) was created. The probe exhibits excellent sensitivity and selectivity for BuChE. NFP-BuChE has been successfully applied to the detection of endogenous BuChE levels in live cells, and we successfully constructed a screening system for BuChEI on cells and a novel natural efficient BuChEI (matrine) was discovered and identified, which significantly reduced BuChE activity and thus alleviated AD symptoms. Most importantly, for the first time, we measured the changes of BuChE levels in zebrafish (0-4 days) after fertilization, various organs of zebrafish, and AD zebrafish modeled by different concentrations of AlCl3 by NFP-BuChE, and at the same time, we also validated the inhibitory effect of matrine on BuChE by NFP-BuChE in zebrafish. In addition, NFP-BuChE has also been successfully used to measure the changes of BuChE levels in the brains of AD mice. These findings imply that NFP-BuChE is a potentially useful molecular tool for screening possible natural BuChEI quickly and for monitoring changes in BuChE activity, and it is expected that more value will be explored in mice. In addition, matrine and its derivatives are promising options for future Alzheimer's disease treatments.

Rational design of Near-Infrared fluorescent probe for monitoring HNO in plants

Nitroxyl (HNO), a reactive nitrogen species (RNS), is essential for plant growth. However, the action of HNO in plants has been difficult to understand due to the lack of highly sensitive and real-time in-situ monitoring tools. Herein, we presented a near-infrared fluorescent probe, DCI-HNO, based on dicyanoisophorone fluorophore, for real-time mapping HNO in plants. The introduction of a phosphine moiety as a specific HNO recognition unit can inhibit the intramolecular charge transfer (ICT) of probe DCI-HNO. However, in the presence of HNO, the ICT process occurred, leading to the emission at 665 nm. Probe DCI-HNO exhibited high sensitivity (97 nM), rapid response time (8 min), large Stokes shift (135 nm) for detection of HNO in plants. The novel developed probe has successfully imaged endogenous HNO produced during NO/H2S cross-talk in plant tissues. Additionally, the up-regulated in HNO levels during tobacco aging and in response to stress has been confirmed. Therefore, probe DCI-HNO has provided a reliable method for monitoring the NO/H2S cross-talk and revealing the role of HNO in plants.

Development of an activatable far-red fluorescent probe for rapid visualization of hypochlorous acid in live cells and mice with neuroinflammation

Recent investigations have suggested that abnormally elevated levels of HOCl may be tightly related to the severity of neuroinflammation. Although some successes have been achieved, fluorescent probes with far-red fluorescence emission and capable of detecting HOCl with high specificity in pure aqueous solution are still urgently needed. Herein, a responsive far-red fluorescent probe, DCI-H, has been constructed to monitor HOCl activity in vivo and in vitro. DCI-H could rapidly respond to HOCl within 120 s and had a low detection limit for HOCl of 1.5 nM. Importantly, physiologically common interfering species, except for HOCl, did not cause a change in the fluorescence intensity of DCI-HOCl at 655 nm. The results of confocal imaging demonstrated the ability of DCI-H to visualize endogenous HOCl produced by MPO-catalyzed H2O2/Cl- and LPS stimulation. With the assistance of DCI-H, upregulation of HOCl levels was observed in the mice model of LPS-induced neuroinflammation. Thus, we believed that DCI-H provided a valuable tool for HOCl detection and diagnosis of inflammation-related diseases.

A Highly Selective Fluorescent Probe for Hydrogen Sulfide and its Application in Living Cell

A new Near-infrared fluorescent probe for hydrogen sulfide detection was synthesized by employing dicyanoisophorone based fluorescence dye as a fluorophore and methyl 3-(2-(carbonyl)phenyl)-2-cyanoacrylate group as the response unit. The Probe DCI-H2S showed a long emission wavelength (λem = 674 nm). Based on the H2S-induced addition-cyclization of deprotecting methyl 3-(2-(carbonyl)phenyl)-2-cyanoacrylate group, the probe DCI-H2S showed high selectivity, sensitivity and response speed toward hydrogen sulfide under room temperature. These numerous advantages of the probe DCI-H2S make it to potentially detect endogenous hydrogen sulfide in living organisms.

Novel Near-Infrared Fluorescence Probe for Bioimaging and Evaluating Superoxide Anion Fluctuations in Ferroptosis-Mediated Epilepsy

Ferroptosis is an iron-regulated, caspase-mediated pathway of cell death that is associated with the excessive aggregation of lipid-reactive oxygen species and is extensively involved in the evolution of many diseases, including epilepsy. The superoxide anion (O2•-), as the primary precursor of ROS, is closely related to ferroptosis-mediated epilepsy. Therefore, it is crucial to establish a highly effective and convenient method for the real-time dynamic monitoring of O2•- during the ferroptosis process in epilepsy for the diagnosis and therapy of ferroptosis-mediated epilepsy. Nevertheless, no probes for detecting O2•- in ferroptosis-mediated epilepsy have been reported. Herein, we systematically conceptualized and developed a novel near-infrared (NIR) fluorescence probe, NIR-FP, for accurately tracking the fluctuation of O2•- in ferroptosis-mediated epilepsy. The probe showed exceptional sensitivity and outstanding selectivity toward O2•-. In addition, the probe has been utilized effectively to bioimage and evaluate endogenous O2•- variations in three types of ferroptosis-mediated epilepsy models (the kainic acid-induced chronic epilepsy model, the pentylenetetrazole-induced acute epilepsy model, and the pilocarpine-induced status epilepticus model). The above applications illustrated that NIR-FP could serve as a reliable and suitable tool for guiding the accurate diagnosis and therapy of ferroptosis-mediated epilepsy.

Near-infrared fluorescent probe with large stokes shift for detecting Human Neutrophil elastase in living cells

Human Neutrophil elastase (HNE) plays a great role in immune responses and inflammation, and is associated closely with lung cancer and acute lung injury (ALI). Accurate detection of its activity is imperative to understand its biological function and diagnosing the disease states through monitoring the dynamic changes. Herein, we report a new NIR fluorescent probe (F-1) with large Stokes shift (182 nm). Probe F-1 featured high sensitivity (LOD ~ 5.6 ng/mL), good selectivity, low toxicity and a bright NIR emission triggered by HNE. Moreover, F-1 was successfully applied as an indicator to track the HNE in the A549 cells. Thus, F-1 may be an excellent tool for detecting enzymatic activity for preclinical applications and NE related diseases.

A novel copper ion sensing fluorescent probe for fast detection of pyrophosphate and alkaline phosphatase

A Cu²⁺ sensing fluorescent probe is synthesized via a Mannich reaction and is applied in the fluorescence detection of pyrophosphate and alkaline phosphatase.