Neo-construction of a SO2-tunable near-infrared ratiometric fluorescent probe for high-fidelity diagnosis and evaluation hazards of Cd2+-induced liver injury

Methoxyl-modulated high-performance ratiometric fluorescent probe with AIE properties for hypochlorite detection and live cell imaging

In recent years, the mechanism concerning fluorescence can be modulated by intramolecular charge transfer (ICT) effect has been widely used in the creation of ratiometric fluorescent probes. However, on this basis, further studies on the structure-activity relationship between molecular constitution of probes and their photophysical characteristics, as well as sensing performance remained less comprehensive. In this work, with triphenylamine (TPA) and methylthio as typical fluorophore and recognition groups respectively, an ICT-based hypochlorite (ClO-) fluorescent probe named Probe A was initially constructed, and then through ingenious molecular design, the second probe defined as Probe B was successfully prepared by introducing methoxyls as electron donors. The subsequent results showed that, compared with Probe A, the Probe B can exhibit superior aggregation-induced emission (AIE) properties and significant ratiometric fluorescence color change from blue to green within 4 min upon the addition of ClO- in a 99 % water content system. Ultimately, the best performing Probe B was successfully applied to ClO- detection in real water samples, the creation of portable test strips for naked-eye identification, and live cell imaging.

A FRET/TICT based multifunctional fluorescent probe for the monitoring of SO2 derivatives and viscosity in living cells and real samples

SO2 derivatives and viscosity are important intracellular indicators, which are closely associated with various physiological metabolisms in organisms. The unregulated contents of SO2 derivatives and viscosity in vivo commonly related to some disorders. In this work, probe JFT was developed relying on FRET and TICT mechanisms for the simultaneous detection of SO2 derivatives and viscosity. JFT can rapidly detect viscosity levels with continuously enhanced fluorescence signals at 582 nm basing on the increasing of viscosity. Moreover, JFT was also sensitive to the changes of SO2 derivatives level with a low detection limit (61.5 nM), rapid responding time (with 16 min), excellent selectivity and anti-interference capacity. JFT could detect bisulfite in real water, wine and food samples with high accuracy and recovery rate. Cell imaging indicated that JFT could monitor the endogenous SO2 derivatives and viscosity in mitochondria. Importantly, JFT could recognize the cancer cells basing on the cell imaging difference of JFT in AGS and GES-1 cells.

Construction of a highly specific fluorescence "turn-on" probe for H2S detection and imaging in drug-induced live cells, zebrafish and mice arthritis models

Quantitatively and selectively detecting the biomarker of hydrogen sulfide (H2S) in arthritis diseases is of great significance for the early diagnosis and treatment of arthritis. Modern medical studies show that H2S as a biomarker is involved in the development of inflammation. In this work, a new highly specific fluorescence "turn-on" probe JMD-H2S was tailored for H2S detection and imaging in drug-induced live cells, zebrafish and mice arthritis models, which utilized pyrazoline molecule as the fluorescence signal reporter group and 2,4-dinitrophenyl ether group (DNB) with strong intramolecular charge transfer (ICT) effect as the H2S recognition moiety and fluorescence quenching group. JMD-H2S showed a fast response time (<60 s), a large fluorescence response ratio (enhanced ∼20 folds) at I453/I0, excellent sensitivity toward H2S over other analytes, and an outstanding limit of detection (LOD) as low as 25.3 nM. In addition, JMD-H2S has been successfully applied for detecting and imaging H2S in drug-induced live cells, zebrafish, and mice arthritis models with satisfactory results, suggesting it can be used as a robust molecular tool for investigating the occurrence and development of H2S and arthritis.

A FRET probe based on flavonol-benzothiazole for the detection of viscosity and SO2 derivatives

Sulfur dioxide (SO2) and viscosity play important roles in living organisms, and abnormal levels of them are associated with many diseases. Hence, a bifunctional fluorescence probe (E)-3-(2-(4-(4-(4-(6-fluoro-3-hydroxy-4-oxo-4H-chromen-2-yl)benzoyl)piperazin-1-yl)styryl)benzo-[d]thiazol-3-ium-3-yl)propane-1-sulfonate (HFBT) with fluorescence resonance energy transfer (FRET) properties was successfully constructed by using 3-hydroxyflavonol as the energy donor and benzothiazole sulphonate derivatives as the energy acceptor, and it can be used for the detection of SO2 derivatives (HSO3-/HSO32-) and viscosity. HFBT exhibits a large Stokes shift (245 nm), high resonance energy transfer efficiency (95.56 %), and excellent selectivity, anti-interference and low limit of detection (LOD = 0.057 μM) for HSO3-. The fluorescence intensity of HFBT at 596 nm gradually increases with the increase of viscosity. Interestingly, a visual HSO3- detection platform was successfully constructed and applied to the quantitative detection of HSO3- in food. Additionally, HFBT was successfully applied to imaging endogenous and exogenous HSO3- in cells. The successful development of HFBT provides an effective tool for the detection and imaging of HSO3- in food and cells.

Construction of a Dual-Mode Sensing Platform for Ultra-fast Detection of Bisulfite in Food and Environmental Systems

Sulfur dioxide (SO2) is widely used in food processing to extend the shelf life of food. However, excessive intake of SO2 and its derivatives (HSO3- and SO32-) can cause oxidative damage to the body, and result in several diseases. How to construct probes for rapid real-time detection of HSO3- in the field is beneficial to the developmental needs of practical applications, but it is also very challenging. Here we report a dual-mode fluorescent probe Rh-QL for ultrafast detection of HSO3-, which undergoes a specific 1,4-Michael addition reaction with HSO3- to achieve near-infrared fluorescence turn-on. Probe Rh-QL can rapidly (< 5 s) respond to HSO3- with a color change from purple to green and a strong fluorescence emission at 725 nm. The probe Rh-QL has been used for the detection of HSO3- in real sugar samples and can be prepared as a portable sensing kit for the detection of HSO3- in the environment due to its high efficiency, rapidity and accuracy. In addition, the probe Rh-QL is able to target label Gram-negative bacteria after reacting with HSO3-, which has the potential to identify the type of pathogenic bacteria.

Visualizing DNA/RNA, Proteins, and Small Molecule Metabolites within Live Cells

Live cell imaging is essential for obtaining spatial and temporal insights into dynamic molecular events within heterogeneous individual cells, in situ intracellular networks, and in vivo organisms. Molecular tracking in live cells is also a critical and general requirement for studying dynamic physiological processes in cell biology, cancer, developmental biology, and neuroscience. Alongside this context, this review provides a comprehensive overview of recent research progress in live-cell imaging of RNAs, DNAs, proteins, and small-molecule metabolites, as well as their applications in molecular diagnosis, immunodiagnosis, and biochemical diagnosis. A series of advanced live-cell imaging techniques have been introduced and summarized, including high-precision live-cell imaging, high-resolution imaging, low-abundance imaging, multidimensional imaging, multipath imaging, rapid imaging, and computationally driven live-cell imaging methods, all of which offer valuable insights for disease prevention, diagnosis, and treatment. This review article also addresses the current challenges, potential solutions, and future development prospects in this field.

Two Squaramide-Based Fluorescent Probes for Cu2+ and Cd2

The development of potential toxic metal ion probes is of great significance in the field of environmental detection. Herein, two squaramide ligands (2a, 2b) were constructed by combining the characteristics of squaric acid and imine groups. 2a and 2b can recognize Cu2+ and Cd2+, with LOD of 1.26 × 10-8 M and 2.04 × 10-8 M, respectively, and have the advantages of fast response and wide pH range. The binding ratio and binding mode of the probe and the target ion were determined by Job's plot, ESI-MS, and 1H NMR.

A near-infrared fluorescent probe with two-photon excitation for in situ imaging of NQO1 in human colorectum cancer tissue

Colorectum cancer has become one of the most fatal cancer diseases, in which NAD(P)H: quinone oxidoreductase 1 (NQO1) plays a role in intracellular free radical reduction and detoxification and has been linked to colorectum cancer and chemotherapy resistance. Therefore, rational design of optical probe for NQO1 detection is urgent for the early diagnosis of colorectum cancer. Herein, we have developed a novel two-photon fluorescent probe, WHFD, which is capable of selectively detecting of intracellular NQO1 with two-photon (TP) absorption (800 nm) and near-infrared emission (620 nm). Combination with a substantial Stokes shift (175 nm) and biocompatibility, we have assessed its suitability for in vivo imaging of endogenous NQO1 activities from HepG2 tumor-bearing live animals with high tissue penetration up to 300 μm. Particularly, we for the first time used the probe to image NQO1 activities from human colorectum cancer samples by using TP microscopy, and proving our probe possesses reliable diagnostic performance to directly in situ imaging of cancer biomarker and can clearly distinguish the boundary between human colorectum cancer tissue and their surrounding normal tissue, which shows great potential for the intraoperative navigation.

Recent Advances in Organic Small-Molecule Fluorescent Probes Based on Dicyanoisophorone Derivatives

Fluorescent probe technology holds great promise in the fields of environmental monitoring and clinical diagnosis due to its inherent advantages, including easy operation, reliable detection signals, fast analysis speed, and in situ imaging capabilities. In recent years, a wide range of fluorescent probes based on diverse fluorophores have been developed for the analysis and detection of various analytes, yielding significant achievement. Among these fluorophores, the dicyanoisophorone-based fluorophores have garnered significant attention. Dicyanoisoporone exhibits minimal fluorescence, yet possesses a robust electron-withdrawing capability, rendering it suitable for constructing of D-π-A structured fluorophores. Leveraging the intramolecular charge transfer (ICT) effect, such fluorophores exhibit near-infrared (NIR) fluorescence emission with a large Stokes shift, thereby offering remarkable advantages in the design and development of NIR fluorescence probes. This review article primarily focus on small-molecule dicyanoisoporone-based probes from the past two years, elucidating their design strategies, detection performances, and applications. Additionally, we summarize current challenges while predicting future directions to provide valuable references for developing novel and advanced fluorescence probes based on dicyanoisoporone derivatives.

Imaging gastrointestinal damage due to acute mercury poisoning using a mitochondria-targeted dual near-infrared fluorescent probe

Mercury (Hg) is one of the most widespread pollutants that pose serious threats to public health and the environment. People are inevitably exposed to Hg via different routes, such as respiration, dermal contact, drinking or diet. Hg poisoning could cause gingivitis, inflammation, vomiting and diarrhea, respiratory distress or even death. Especially during the developmental stage, there is considerable harm to the brain development of young children, causing serious symptoms such as intellectual disability and motor impairments, and delayed neural development. Therefore, it's of great significance to develop a specific, quick, practical and labor-saving assay for monitoring Hg2+. Herein, a mitochondria-targeted dual (excitation 700 nm and emission 728 nm) near-infrared (NIR) fluorescent probe JZ-1 was synthesized to detect Hg2+, which is a turn-on fluorescent probe designed based on the rhodamine fluorophore thiolactone, with advantages of swift response, great selectivity, and robust anti-interference capability. Cell fluorescence imaging results showed that JZ-1 could selectively target mitochondria in HeLa cells and monitor exogenous Hg2+. More importantly, JZ-1 has been successfully used to monitor gastrointestinal damage of acute mercury poisoning in a drug-induced mouse model, which provided a great method for sensing Hg species in living subjects, as well as for prenatal diagnosis.