An NBD-based colorimetric and fluorescent chemosensor for Zn2+ and its use for detection of intracellular zinc ions

Readily Accessible and Brightly Fluorogenic BODIPY/NBD-Tetrazines via SNAr Reactions

We describe SNAr reactions of some commercial amino-tetrazines and halo-dyes, which give efficiently quenched BODIPY/NBD-tetrazines (ΦFl < 0.01) in high yields and, importantly, with high purities affordable via simple silica gel chromatography only. The dyes exhibit large Stokes shifts, moderate environmental sensitivity, and emission enhancements (up to 193-fold) upon Tz ligation with BCN─a strained dienophile. They successfully serve as labels for HSA protein premodified with BCN, resulting in bright blue-green emission upon ligation.

Recent Advancements and Future Prospects in NBD-Based Fluorescent Chemosensors: Design Strategy, Sensing Mechanism, and Biological Applications

In recent years, the field of Supramolecular Chemistry has witnessed tremendous progress owing to the development of versatile optical sensors for the detection of harmful biological analytes. Nitrobenzoxadiazole (NBD) is one such scaffold that has been exploited as fluorescent probes for selective recognition of harmful analytes and their optical imaging in various cell lines including HeLa, PC3, A549, SMMC-7721, MDA-MB-231, HepG2, MFC-7, etc. The NBD-derived molecular probes are majorly synthesized from the chloro derivative of NBD via nucleophilic aromatic substitution. This general NBD moiety ligation method to nucleophiles has been leveraged to develop various derivatives for sensing analytes. NBD-derived probes are extensively used as optical sensors because of remarkable properties like excellent stability, large Stoke's shift, high efficiency and stability, visible excitation, easy use, low cost, and high quantum yield. This article reviewed NBD-based probes for the years 2017-2023 according to the sensing of analyte(s), including cations, anions, thiols, and small molecules like hydrogen sulfide. The sensing mechanism, designing of the probe, plausible binding mechanism, and biological application of chemosensors are summarized. The real-time application of optical sensors has been discussed by various methods, such as paper strips, molecular logic gates, smartphone detection, development of test kits, etc. This article will update the researchers with the in vivo and in vitro biological applicability of NBD-based molecular probes and challenges the research fraternity to design, propose, and develop better chemosensors in the future possessing commercial utility.

A fluorescence based dual sensor for Zn2+ and PO43- and the application of soft computing methods to predict machine learning outcomes

A phenolphthalein-based Schiff base, 3,3-bis-{4-hydroxy-3-[(pyridine-2-ylmethylimino)-methyl]-phenyl}-3H-isobenzofuran-1-one (PAP), has been synthesized and used for selective fluorescence 'turn on' and 'turn off' sensing of Zn2+ and PO43- respectively. The limit of detection using the 3σ method for Zn2+ is found to be 19.3 nM and that for PO43- is 8.3 μM. The sensing mechanism of PAP for Zn2+ ions has been explained by 1H NMR, 13C NMR, TRPL, ESI-MS, FT-IR, and DFT based calculations. Taking advantage of this fluorescence 'on-off' behavior of PAP in the sequential presence of Zn2+ and PO43- a two input fuzzy logic (FL) operation has been constructed. The chemosensor PAP can thus act as a metal ion and anion responsive molecular switch, and its corresponding emission intensity is used to mimic numerous FL functions. To replace various expensive, time-consuming experimental procedures, we implemented machine learning soft computing tools, such as fuzzy-logic, artificial neural networks (ANNs), and adaptive neuro-fuzzy inference systems (ANFIS), to correlate as well as predict the fluorescence intensity in the presence of any equivalent ratio of Zn2+ and PO43-. The statistical performance measures (MSE and RMSE, for example) show that the projected values of the cation and anion sensing data by the ANFIS network are the best and closer to the experimental values.

Synthesis and Applications of Fluorescent Chemosensors: A Review

Fluorescent sensors have emerged as powerful tools in analytical chemistry for the detection and quantification of heavy and transition metal ions in aqueous samples. These metal ions pollute the environment and cause a number of diseases, such as irritability, anaemia, muscle paralysis, neurological damage, and memory loss. Moreover, we explore the wide spectrum of applications in environmental monitoring, where these sensors enable precise detection of contaminants, as well as in biomedical fields, facilitating diagnostic and therapeutic advancements. While highlighting the exceptional progress achieved in this field, I also address the challenges and future prospects for the continued development of fluorescent sensors, emphasizing their potential to shape the future of water quality assessment and analytical chemistry. Heavy and transition metals are of great concern because of their extreme toxicity even at very low concentration and tendency to be accumulated in bodies of living organisms. During the recent years, the design and synthesis of fluorescent chemosensors for sensing environmentally and biologically relevant important metals, particularly for heavy and transition metals, is of great interest. Opon complexation with heavy and transition metals, the fluorescence intensity of these fluorescent chemosensors either quenched or enhanced. The current review paper explains various fluorescent chemosensors for determination of toxic heavy and transition metals in environmental water samples.

Development of electrochemical Zn2+ sensors for rapid voltammetric detection of glucose-stimulated insulin release from pancreatic β-cells

Diabetes is a chronic disease characterized by elevated blood glucose levels resulting from absent or ineffective insulin release from pancreatic β-cells. β-cell function is routinely assessed in vitro using static or dynamic glucose-stimulated insulin secretion (GSIS) assays followed by insulin quantification via time-consuming, costly enzyme-linked immunosorbent assays (ELISA). In this study, we developed a highly sensitive electrochemical sensor for zinc (Zn2+), an ion co-released with insulin, as a rapid and low-cost method for measuring dynamic insulin release. Different modifications to glassy carbon electrodes (GCE) were evaluated to develop a sensor that detects physiological Zn2+ concentrations while operating within a biological Krebs Ringer Buffer (KRB) medium (pH 7.2). Electrodeposition of bismuth and indium improved Zn2+ sensitivity and limit of detection (LOD), and a Nafion coating improved selectivity. Using anodic stripping voltammetry (ASV) with a pre-concentration time of 6 min, we achieved a LOD of 2.3 μg/L over the wide linear range of 2.5-500 μg/L Zn2+. Sensor performance improved with 10-min pre-concentration, resulting in increased sensitivity, lower LOD (0.18 μg/L), and a bilinear response over the range of 0.25-10 μg/L Zn2+. We further characterized the physicochemical properties of the Zn2+ sensor using scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Finally, we demonstrated the sensor's capability to measure Zn2+ release from glucose-stimulated INS-1 β-cells and primary mouse islets. Our results exhibited a high correlation with secreted insulin and validated the sensor's potential as a rapid alternative to conventional two-step GSIS plus ELISA methods.

A fluorescent probe based on Cu(II) complex induced catalysis for repetitive detection of cysteine

Real-time imaging and monitoring of biothiols in living cells are essential for understanding pathophysiological processes. However, the design of the fluorescent probe that has accurate and repeatable real-time monitoring capabilities for these targets is highly challenging. In this study, we prepared a fluorescent sensor, Lc-NBD-Cu(II), which contains a N1, N1, N2-tris-(pyridin-2-ylmethyl) ethane-1,2-diamine as a Cu(II) chelating unit and a 7-nitrobenz-2-oxa-1,3-diazole fluorophore to detect Cysteine (Cys). Emission changes promoted by addition of Cys to this probe are distinctive and correspond to a range of processes including Cys induced loss of Cu(II) from Lc-NBD-Cu(II) to form Lc-NBD, Cu(I) oxidation to reform Cu(II), Cys oxidation to form Cys-Cys, Cu(II) binding to Lc-NBD to reform Lc-NBD-Cu(II), and competitive binding of Cu(II) to Cys-Cys. The study also shows that Lc-NBD-Cu(II) maintains high stability during the sensing process and that it can be utilized over a number of detection cycles. Finally, the findings show that Lc-NBD-Cu(II) can be utilized to repetitively sense Cys in living HeLa cells.

A quinazolin-based Schiff-base chemosensor for colorimetric detection of Ni2+ and Zn2+ ions and 'turn-on' fluorometric detection of Zn2+ ion

Herein, we have reported a novel quinazolin-based Schiff base chemosensor (E)-2-benzamido-N'-(1-(pyridin-2-yl)ethylidene)benzohydrazide (L). L has been designed, synthesised and characterised by 1H-NMR, IR spectroscopy, ESI-MS spectrometry and theoretical studies. The receptor showed appreciable colorimetric λ max shift for both Ni2+ and Zn2+ ions and fluorometric "turn on" response in presence of only Zn2+ ion. The Jobs plot analysis revealed that receptor forms 2 : 1 complex with both the ions Ni2+ and Zn2+, further confirmed by ESI-MS analysis. The single crystal structure of L-Ni2+ complex (1) has also been determined. The colorimetric detection limits were calculated to 7.9 nM and 7.5 nM respectively for Ni2+ and Zn2+ in methanol-Tris-HCl buffer medium (10 mM, pH 7.2, 1 : 1 v/v). The chemosensor L can be applied for the recovery of contaminated water samples.

Biological Application of a Fluorescent Zinc Sensing Probe for the Analysis of Zinc Bioavailability Using Caco-2 Cells as an In-Vitro Cellular Model

Zinc is essential for growth and development of all living organisms, especially human being. Deficiency of micronutrients like zinc and iron has been linked to the manifestation of hidden hunger. Therefore, it is imperative that development of some rapid screening method for bioavailable zinc in various crops and food commodities would be an essential addition in battle against zinc deficiency related hidden hunger. One such method could be the usage of fluorescence based zinc ion sensing probe which would be robust and convenient for estimating bioavailable zinc. To address this issue, NBD-TPEA, a highly sensitive zinc ion sensing probe, have been used in this study towards the development of a novel fluorescence based approach for the analysis of zinc bioavailability in Caco-2 cells as an in-vitro cellular model. The use of this probe showed dose dependent sensitivity towards increasing concentrations of zinc ion uptake by Caco-2 cells. It also showed specificity for zinc ion uptake as compared to other metal ions in-vitro. These observations correlated extremely well with zinc uptake analysis by cell imaging and conventional analytical technique like, ICP-MS. The developed assay was then tested in mushroom and some selected biofortified derivatives of wheat for determining the levels of their bioavailable zinc using Caco-2 cells. The data as obtained with these food samples in our developed bioassay correlated well with the other sophisticated analytical techniques thus validating our cell based assay. Hence, the developed assay could serve as a simple but sensitive tool for determining bioavailable zinc in various food samples.

Coumarin-based colorimetric-fluorescent sensors for the sequential detection of Zn2+ ion and phosphate anions and applications in cell imaging

Two novel coumarin based fluorescent sensors CHP and CHS have been synthesized for the sequential detection of Zn²⁺ ion and phosphate anion (PA) in DMF/HEPES buffer medium (1/5 v/v, 10 mM, pH = 7.4). On the addition of Zn²⁺ ion to the solution of CHP or CHS resulted in a pronounced fluorescence enhancement, accompanying noticeable color change (under UV or daylight), while there was hardly obvious change with other competing metal ions co-existing. The detection limits (DL) of CHP and CHS toward Zn²⁺ were separately determined as 1.03 × 10^-7 (R² = 0.9886) and 1.87 × 10^-7 (R² = 0.9902). The PET binding processes were affirmed by spectroscopic techniques, HRMS experiments and theoretical calculations. Subsequently, the CHP-Zn²⁺ or CHS-Zn²⁺ complexes showed high selectivity fluorescence quenching toward PA by snatching Zn²⁺ ion from its complex and the binding processes were reversible. DLs were calculated as 2.07 × 10^-7 M (R² = 0.9928) and 2.63 × 10^-7 M (R² = 0.9954), respectively. Furthermore, the cell imaging experiments demonstrated that the sensors were capable of detecting of Zn²⁺ and PA in vitro cells.

New colorimetric and fluorometric chemosensor for selective Hg2+ sensing in a near-perfect aqueous solution and bio-imaging

We report a new 7-nitrobenzo-2-oxa-1, 3-diazolyl (NBD)-based chemosensor containing a piperazine derivative, NBDP, for detection of mercury ions in almost 100% aqueous medium. The chemosensor shows sensing exclusively toward Hg²⁺ with a switch-on fluorescence response at 543 nm, which could be attributed to the blocking of PET (photo-induced electron transfer) process upon complexation with mercury ions. The molar ratio of Hg(Ⅱ) to NBDP in the complex is 1:1 based on the Job's plot and HRMS studies. Optimized configurations of NBDP and NBDP-Hg²⁺ complexes were simulated by means of DFT calculations. The reversible fluorescence response with low detection limit (19.2 nM) in the pH range of 6.0-7.5 renders NBDP a promising candidate for Hg²⁺ detection in neutral aqueous environments. For the practical application of the chemosensor, test strips were successfully fabricated for rapid detection of Hg²⁺ ions. Moreover, the utility of NBDP showing the mercury recognition in Human liver cancer cells (SMMC-7721) and zebrafish as well as in live tissues of Arabidopsis thaliana has been demonstrated as monitored by fluorescence imaging.

Specific heavy metal/metalloid sensors: current state and perspectives

Heavy metal(loid)s play pivotal roles in regulating physiological and developmental aspects in living organisms depending on their concentration. For example, a trace amount of heavy metal(loid)s is essential for living organisms, but heavy metal(loid)s in high concentrations negatively affect their physiology and development. Because of rapid industrial developments, heavy metal(loid)s have been accumulating in environmental systems, thereby becoming a threat to human health and the earth's ecosystem. Thus, the development of tools to quantify and monitor heavy metal(loid)s in environmental systems has become essential. Typically, risk has been determined through instrument-based analysis, regardless of the shortcomings regarding expense and duration. Nowadays, the need for alternative tools, besides instrumental analysis, to detect heavy metals has prompted the development of new techniques, and many different methods have been reported from various research areas, including new techniques based on electrochemistry and biological systems. Nonetheless, it seems that the gap between laboratory and fieldwork is still greater than it should be when it comes to applying these systems. In this mini-review, we discuss the current status of heavy metals/metalloid detection techniques, with an emphasis on biosensors. Moreover, we discuss the advantages and disadvantages as well as the mechanisms behind newly developed sensors and make suggestions to improve applicability and to develop new objective targeting sensors. Although many different types of metal(loid) sensors are available, we focused on metal sensors based on biological systems. Additionally, we suggest potent approaches to developing new biosensor systems based on current metal sensor mechanisms.

A unique benzimidazole-naphthalene hybrid molecule for independent detection of Zn2+ and N3- ions: Experimental and theoretical investigations

Single crystal X-ray structurally characterized benzimidazole-naphthalene hybrid (NABI) functions as a unique dual analyte sensor that can detect Zn²⁺ cation and N₃^- anion independently. The NABI forms chelate with Zn²⁺ to inhibit internal charge transfer (ICT) and CHN isomerisation resulting chelation enhanced fluorescence (CHEF). On the other hand, the sensing of N₃^- is based on formation of supramolecular H-bonded rigid assembly. The association constant of NABI for Zn²⁺ and N₃^- ions are 19 × 10⁴ M^-1 and 11 × 10² M^-1, respectively. Corresponding limit of detections (LOD) are 6.85 × 10^-8 and 1.82 × 10^-7 M, respectively. NABI efficiently detects intracellular Zn²⁺ and N₃^- ions with no cytotoxicity on J774A.1cells under fluorescence microscope. DFT studies unlock underlying spectroscopic properties of free NABI and Zn²⁺/N₃^- bound forms.

A coumarin based highly sensitive fluorescent chemosensor for selective detection of zinc ion

A very effective and highly sensitive fluorescent chemosensor, based on 4-hydroxycoumarin skeleton substituted by benzothiazole moiety was synthesized and investigated for the detection of zinc ion. This chemosensor displays highly selective and sensitive fluorescence enhancement to Zn²⁺ over other metal ions examined in solution and in biological systems. The detection limit for the fluorescent chemosensor 1 toward Zn²⁺ was 3.58 × 10^-8 M. A simple and efficient approach was improved for the synthesis of chemosensor 1 starting from 4-hydroxycoumarin.

A multiple target chemosensor for the sequential fluorescence detection of Zn2+ and S2− and the colorimetric detection of Fe3+/2+ in aqueous media and living cells

A novel multiple target sensor DHIC was developed for the fluorescence detection of Zn²⁺ and S²⁻ and colorimetric detection of Fe^3+/2+. Moreover, DHIC could image sequentially Zn²⁺ and S²⁻ in living cells.

A dual-response sensor based on NBD for the highly selective determination of sulfide in living cells and zebrafish

A dual chemosensor, 1-NO₂, showing fluorogenic and colorimetric responses was developed for the detection of sulfide in vitro and in vivo.

Fluorescent Chemosensors for Various Analytes Including Reactive Oxygen Species, Biothiol, Metal Ions, and Toxic Gases

The development of fluorescent chemosensors for various analytes has been actively pursued by chemists. Since their inception, these efforts have led to many new sensors that have found wide applications in the fields of chemistry, biology, environmental science, and physiology. The search for fluorescent chemosensors was initiated by a few pioneering groups in the late 1970s and 1980s and blossomed during the last two decades to include more than hundreds of research groups around the world. The targets for these sensors vary from metal ions, anions, reactive oxygen/nitrogen species, biothiols, and toxic gases. Our group has made contributions to this area in last 18 years. In this perspective, we briefly introduce the history of chemosensors and review studies that we have carried out.

A novel turn-on fluorescent probe for the multi-channel detection of Zn2+ and Bi3+ with different action mechanisms

A novel multifunctional sensor, RSPT, was identified and developed for multichannel turn-on fluorescent responses to Zn²⁺ and Bi³⁺ in practice.

Localization of all four ZnT zinc transporters in Dictyostelium and impact of ZntA and B knockout on bacteria killing

Professional phagocytes have developed an extensive repertoire of autonomous immunity strategies to ensure killing of bacteria. Besides phagosome acidification and the generation of reactive oxygen species, deprivation of nutrients and the lumenal accumulation of toxic metals are essential to kill ingested bacteria or inhibit growth of intracellular pathogens. We use the soil amoeba Dictyostelium discoideum, a professional phagocyte that digests bacteria for nutritional purposes, to decipher the role of zinc poisoning during phagocytosis of non-pathogenic bacteria and visualize the temporal and spatial dynamics of compartmentalized, free zinc using fluorescent probes. Immediately after particle uptake, zinc is delivered to phagosomes by fusion with “zincosomes” of endosomal origin, but also by the action of one or more zinc transporters. We localize the four Dictyostelium ZnT transporters to endosomes, the contractile vacuole and the Golgi apparatus, and study the impact of znt knockouts on zinc homeostasis. Finally, we show that zinc is delivered into the lumen of Mycobacterium smegmatis-containing vacuoles, and that Escherichia coli deficient in the zinc efflux P1B-type ATPase ZntA is killed faster than wild type bacteria.

Green and Red Fluorescent Dyes for Translational Applications in Imaging and Sensing Analytes: A Dual-Color Flag

Red and green are two of the most-preferred colors from the entire chromatic spectrum, and red and green dyes are widely used in biochemistry, immunohistochemistry, immune-staining, and nanochemistry applications. Selective dyes with green and red excitable chromophores can be used in biological environments, such as tissues and cells, and can be irradiated with visible light without cell damage. This critical review, covering a period of five years, provides an overview of the most-relevant results on the use of red and green fluorescent dyes in the fields of bio-, chemo- and nanoscience. The review focuses on fluorescent dyes containing chromophores such as fluorescein, rhodamine, cyanine, boron-dipyrromethene (BODIPY), 7-nitobenz-2-oxa-1,3-diazole-4-yl, naphthalimide, acridine orange, perylene diimides, coumarins, rosamine, Nile red, naphthalene diimide, distyrylpyridinium, benzophosphole P-oxide, benzoresorufins, and tetrapyrrolic macrocycles. Metal complexes and nanomaterials with these dyes are also discussed.

Synthesis and structural studies of N-heterocyclic carbene Ag(I) and Hg(II) complexes and recognition of dihydrogen phosphate anion

Bis-benzimidazolium salt (S)-2,2'-bis[2″-(N-Et-benzimidazoliumyl)ethoxy]-1,1'-binaphthyl hexafluorophosphate [(S)-L1H2]·(PF6)2 and bis-imidazolium salts (S)-2,2'-bis[2″-(N-R-imidazoliumyl)ethoxy]-1,1'-binaphthyl hexafluorophosphate [(S)-L2H2]·(PF6)2 and [(S)-L3H2]·(PF6)2 (R = ethyl or benzyl), as well as their five N-heterocyclic carbene Hg(II) and Ag(I) complexes such as [(S)-L1Hg(HgBr4)] (1), [(S)-L2Hg(HgBr4)] (2), [(S)-L2Hg(HgI4)] (3), {[(S)-L2Ag](PF6)}n (4) and [(S)-L3Ag](PF6) (5) have been prepared and characterized. Each of complexes 1-3 consists of two rings (one 6-membered ring and one 11-membered ring), in which the oxygen atom in the ligand participates in coordination with Hg(II) ion. In complex 4, 1D helical polymeric chain is formed via biscarbene ligand (S)-L2 and Ag(I) ion. A 15-membered macrometallocycle is constructed through a ligand (S)-L3 and a Ag(I) ion in complex 5. Additionally, the selective recognition of H2PO4- using complex 5 as a receptor was investigated on the basis of fluorescence and UV/vis spectroscopic titrations. The results indicate that complex 5 can distinguish effectively H2PO4- from other anions.

A fluorescence “turn-on” chemosensor for Hg2+and Ag+based on NBD (7-nitrobenzo-2-oxa-1,3-diazolyl)

A fluorescence “turn-on” chemosensor for the simultaneous detection of Hg²⁺and Ag⁺was developed and practically applied with test strips.

A conveniently prepared and hypersensitized small molecular fluorescent probe: Rapidly detecting free zinc ion in HepG2 cells and Arabidopsis

In this paper, we reported a conveniently prepared fluorescent probe for zinc ions detection, which constructed by the condensation reaction between p-(benzothiazolyl)aniline with 4, 4- diethylaminesalicylaldehyde. The sensing ability of the probe toward zinc ions in vitro was tested by a series of UV-Vis and fluorescence spectroscopy studies, which showed that the probe possessed high sensitivity with a detection limit of 5.8nM and a rapid response time of 10s. We also carried out fluorescent bio-imaging of the probe for zinc ions in human liver hepatocellular carcinoma cells (HepG2), which showed that the probe could be utilized to detect the intracellular endogenous zinc ions visually without introducing external zinc sources. Meanwhile, co-staining experiment with organelle selective trackers was performed to illustrate that the probe could locate at endoplasmic reticulum. Finally, we successfully used it as a zinc ion developer in plant tissue, which clearly demonstrated the distribution of zinc ions in the growth stage of plant tissue.

A colorimetric and fluorometric NBD-based chemosensor for highly selective recognition of palladium(ii) cations

A chemosensor NBD-PMA with colorimetric and fluorometric responses for Pd²⁺ cations has been described.

A new water-soluble and colorimetric fluorescent probe for highly sensitive detection of organophosphorus pesticides

A new water-soluble fluorescent probe bearing 1,8-naphthalimide dye, a quaternary ammonium salt and a boronate group was developed for the detection of organophosphorus pesticides.

Recent Progress in Fluorescent Imaging Probes

Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn²⁺, Hg²⁺, Cu²⁺ and Au³⁺, and anions including cyanide and adenosine triphosphate (ATP).

Highly selective and sensitive fluorescence chemosensor for the detection of palladium species based on Tsuji-Trost reaction

A new chemosensor 7-nitro-2,1,3-benzoxadiazole-4-allyl-N-(thiophen-2-ylmethyl)carbamate (NBDTC) was synthesized and utilized for palladium detection based on the Tsuji-Trost reaction. NBDTC displayed specific and ratiometric fluorescent responses toward palladium species. The chemosensor showed more than 50-fold enhancement in fluorescence intensity with the presence of PEG400 and palladium because NBDTC can be transformed to NBDT under palladium-catalyzing Tsuji-Trost reaction. NBDTC displayed high selectivity and sensitivity for palladium species with the detection limit of 1.13×10(-9) M.

A simple pincer-type chemosensor for reversible fluorescence turn-on detection of zinc ion at physiological pH range

A dihydrazone based pincer-type chemosensor (Y) which could detect zinc at physiological pH range with reversible fluorescence “Off–On–Off”.

A highly selective CHEF-type chemosensor for monitoring Zn2+ in aqueous solution and living cells

A new quinolone-based chemosensor was synthesized and successfully applied to quantify and image Zn²⁺ in water samples and living cells.

Highly selective colorimetric and fluorescent detection for Hg2+ in aqueous solutions using a dipeptide-based chemosensor

A dipeptide-based chemosensor selectively and sensitively detected Hg^II in aqueous solutions by colorimetric change and fluorescent change.

Highly sensitive colorimetric detection of HgII and CuII in aqueous solutions: from amino acids toward solid platforms

A chemosensor (NBD-H) based on an amino acid with 7-nitro-2,1,3-benzoxadiazole was used for selective detection of Hg^II and Cu^II among 15 metal ions in aqueous solutions by a colorimetric change and fluorescence change.

Highly sensitive and selective chemosensors for Cu2+and Al3+based on photoinduced electron transfer (PET) mechanism

Two new fluorescent PET chemosensors were synthesised from an acridine core. The sensors can be used to monitor Cu²⁺and Al³⁺in CH₃CN. The detection limits for7a–Cu²⁺and7b–Al³⁺were calculated to be 2.8 × 10⁻⁷M and 5.8 × 10⁻⁷M, respectively.