Zhen Zhang, Yuan Zou, Jihua Liu. A single 8-hydroxyquinoline-appended bile acid fluorescent probe obtained by click chemistry for solvent-dependent and distinguishable sensing of zinc(II) and cadmium(II). LUMINESCENCE, 2024, 39, e4610.

Construction of fluorescent probes for zinc ion (Zn²⁺) and cadmium ion (Cd²⁺) is significant for the safety of humans. However, the discriminating recognition of Zn²⁺ and Cd²⁺ by a single probe remains challenging owing to their similar properties. Herein, a novel deoxycholic acid derivative containing 8-hydroxyquinoline fluorophore has been facilely synthesized through click chemistry to form a clamp-like probe. Using its perfect bonding cavity from 1,2,3-triazole and quinoline, this molecule showed favorable solvent-dependent fluorescent responses and distinguished Zn²⁺ and Cd²⁺ in different solvents. In ethanol aqueous solution, it displayed good selectivity and ratiometric fluorescence to Zn²⁺ with 30 nm spectroscopic red-shifts. In acetonitrile aqueous solution, it exhibited good selectivity and ratiometric fluores- cence to Cd²⁺ with 18 nm spectroscopic red-shifts. Moreover, the unique microstructural features of the probe in assembly were used to reflect its recognition processes. Due to its merits of low detection limit and instant response time, the probe was utilized for sensing Zn²⁺ and Cd²⁺ in water, beer and urine with high accuracy. Meanwhile, this probe served as a handy tool and was employed to obtain inexpensive test strips for the prompt and semiqualitative analysis of Zn²⁺ and Cd²⁺ with the naked eye.

Huanhuan Song, Zhen Zhang*. A quinoline-based ratiometric fluorescent probe for discriminative detection of Zn²⁺ and Cd²⁺ with different binding modes, and its Zn²⁺ complex for relay sensing of pyrophosphate and adenosine triphosphate. Dyes and Pigments, 2019, 165, 172.

    A new and simple quinoline-based fluorescent probe for discriminative sensing of Zn²⁺ and Cd²⁺ has been synthesized by inserting an amide group into the 8-aminoquinoline fluorophore and a propargylamine chelating site. This easily-available chemosensor displayed selective and distinct ratiometric fluorescence responses to Zn²⁺ in almost totally water solution through its amide tautomer binding form, and to Cd²⁺ in CH₃CN aqueous medium through its imidic acid tautomer binding form, respectively. Moreover, the in situ prepared probe 1–Zn²⁺ complex could act as a relay fluorescent sensor selectively toward pyrophosphate (PPi) and adenosine 5’-triphosphate (ATP) anions via further complexation. Thus, with good specificity, low detection limits and fast response time, a highly efficient fluorescence platform for simultaneous multi-analyte detection has been developed by using the uncomplicated single molecule. Finally, this multi-functional probe was applied successfully for analysis of all the target ions in the tap water sample and on test paper strips, and bioimaging of Zn²⁺ in mung bean sprouts with low phytotoxicity.

Zhen Zhang*, Chengquan Deng, Huanhuan Song. A novel rhodamine-based turn-on fluorescent probe for dual detection of Cr³⁺ and Cu²⁺ with solvent-dependent binding properties. Inorganic Chemistry Communications, 2018, 95, 56. 

    A new and simple 8-aminoquinoline–rhodamine conjugate-based fluorescent probe was constructed. This chemosensor displayed simultaneously significant fluorescent enhancement for Cr³⁺ in CH₃CN solution and Cu²⁺ in ethanol solution with high selectivity and sensitivity. The solvent-dependent binding modes provided facile and efficient dual-analyte fluorescent detection. Besides, the concomitant differentiable colorimetric changes with Cr³⁺ and Cu²⁺ in CH₃CN medium contributed easy and sensitive analysis of both cations by absorbance measurements and naked eyes. Finally, the probe was applied to detect Cr³⁺ and Cu²⁺ on silica gel plates.

Zhen Zhang*, Chengquan Deng, Yuan Zou, Lei Chen. A novel fluorescent and colorimetric probe for cascade selective detection of Fe(III) and pyrophosphate based on a click generated cyclic steroid-rhodamine conjugate. Journal of Photochemistry and Photobiology A: Chemistry, 2018, 356, 7.

    A novel fluorescent and colorimetric probe containing deoxycholic acid and rhodamine moieties was developed by click chemistry, and its cascade selective detection of ferric ion (Fe³⁺) and pyrophosphate (PPi) was investigated in details by spectral measurements. The probe displayed turn-on orange fluorescence and colorless to pink color change upon binding with Fe³⁺ by reversibly forming the metal complex and opening the spirolactam ring of rhodamine. Through a tandem ligand exchange, PPi with higher affinity for Fe³⁺ removed the metal from the complex and restored the spectral signal of the probe. The experimental results suggested that this novel molecule could serve as an efficient and economical dual signal chemosensing system for cascade bi-target analysis of Fe³⁺ and PPi with high selectivity, low detection limits and fast response time. Notably, this bi-functional probe also showed excellent performances in monitoring Fe³⁺ and PPi on silica gel plates, in water samples and living cells.

Zhen Zhang*, Yuan Zou, Chengquan Deng. A novel and simple solvent-dependent fluorescent probe based on a click generated 8-aminoquinoline–steroid conjugate for multi-detection of Cu(II), oxalate and pyrophosphate. RSC Advances, 2017, 7, 14742.

    In this work, a novel and simple deoxycholic acid-based fluorescent probe for solvent-dependent multi-detection of Cu²⁺, C₂O₄^2– and P₂O₇^4– has been facilely constructed by click chemistry. This probe displayed sensitive recognition toward Cu²⁺ in low-water-content CH₃CN aqueous solution (CH₃CN–H₂O, 99/1, v/v) via strong fluorescence quenching. Whereas, in DMSO–H₂O medium (1/1, v/v), it exhibited significant fluorescent enhancement for C₂O₄^2– and P₂O₇^4– over a wide range of tested anions. Moreover, with low detection limits and fast response time, the developed fluorescent molecule was used successfully for analysis of the target ions on test paper strips and in water samples.

Zhen Zhang*, Yuan Zou, Chengquan Deng, Liesu Meng. A simple rhodamine hydrazide-based turn-on fluorescent probe for HOCl detection. Luminescence, 2016, 31, 997.

    Hypochlorous acid (HOCl) plays a crucial role in daily life and mediates a variety of physiological processes, but abnormal levels of HOCl has been associated with numerous human diseases. It is therefore of significant interest to establish a simple, selective, rapid, and sensitive fluorogenic detection of HOCl in environmental and biological samples. A hydrazide-containing fluorescent probe based on a rhodamine scaffold was facilely developed that could selectively detect HOCl over other biologically relevant reactive oxygen species (ROS), reactive nitrogen species (RNS), and most of the common metal ions in vitro. By an irreversible oxidation–hydrolysis mechanism, upon HOCl-triggered opening of the intramolecular spirocyclic ring during the detection, the rhodamine hydrazide-based probe exhibited large fluorescence enhancement in the emission spectra with fast response, low detection limit, and comparatively wide pH detection range in aqueous media. The probe was further successfully applied to monitoring trace HOCl in real tap water and imaging both exogenous and endogenous HOCl within living cells. It is anticipated that the simple and useful probe might be an efficient tool to facilitate more HOCl-related chemical and biological researches.

Zhen Zhang*, Chengquan Deng, Liesu Meng, Yan Zheng, Xiaomei Yan. A rhodamine hydrazide-based fluorescent probe for sensitive and selective detection of hypochlorous acid and its application in living cells. Analytical Methods, 2015, 7, 107.

    A simple rhodamine hydrazide-based fluorescent turn-on probe was developed for fluorescence detection of hypochlorous acid (HOCl) in aqueous media and living cells. On the basis of a HOCl-mediated oxidation-hydrolysis mechanism, this new probe features high sensitivity, comparatively wide pH detection range, fast-response, and great photostability toward HOCl in aqueous solution. Owing to its hydrazide structure, the probe also exhibits excellent selectivity for HOCl over a panel of biologically relevant reactive oxygen species (ROS), reactive nitrogen species (RNS), and most of the common metal ions in neutral buffer. Particularly, with cell membrane permeability and low cytotoxicity, the probe is capable of responding to intracellular changes in HOCl levels in living cells by fluorescence imaging and flow cytometry.

张祯*, 邓成权, 郭添, 孟列素. 一种罗丹明类次氯酸荧光探针的合成与分析应用. 分析测试学报, 2014, 33, 7.

    以罗丹明为荧光团，肼为识别基团，通过一步反应合成了一种次氯酸(HOCl)荧光探针罗丹明6G酰肼，用核磁和质谱对探针结构进行了表征，并研究了其检测HOCl的荧光性能。实验结果表明，探针对HOCl的荧光分析具有较高的灵敏性和选择性。利用不可逆的氧化还原反应，探针在中性溶液中快速产生与HOCl浓度呈线性比例的荧光增强信号，检测的线性范围为2~400 μmol/L，检出限为0.06 μmol/L，其他常见活性氧物种对检测影响小。探针能够可视化分析HOCl，并在Hela活细胞中实现了HOCl的荧光成像。

Zhen Zhang*, Yan Zheng, Wei Hang, Xiaomei Yan, Yufen Zhao. Sensitive and selective off–on rhodamine hydrazide fluorescent chemosensor for hypochlorous acid detection and bioimaging. Talanta, 2011, 85, 779.

    A rhodamine 6G hydrazide fluorescent chemosensor was prepared for the rapid HOCl detection in aqueous media. The system makes good use of the irreversible HOCl-mediated selective oxidation reaction to generate fluorescent response proportional to the amount of HOCl in neutral buffer. This probe exhibits great photostability, high sensitivity, and good selectivity for HOCl over other reactive species and most of the common metal ions. Furthermore, the probe is cell membrane permeable, and its applicability has been successfully demonstrated for fluorescence imaging of both exogenous and endogenous HOCl within living cells. Cytotoxicity assays prove that this probe is almost nontoxic to the cultured cell lines under the experimental conditions.