Imaging Of Hg2 Research Articles

A Fluorescent Probe with Large Stokes Shift Based on Benzothiadiazole Scaffolds for Selective Detection of Hg2+ in Lysosomes and Its Application in Biological Imaging.

Mercury is highly toxic, and appropriate amounts of the mercury-selenium complex can protect plasma. However, when excessive mercury (II) ions (Hg2+) are exposed to human skin or ingested directly, it can lead to irreversible accumulation in the body. Therefore, detecting the presence of Hg2+ in cells is important. A novel fluorescent probe BTD-Hg-Lyso was designed and constructed based on the intramolecular charge transfer mechanism. Thiotaldehyde could specifically recognize Hg2+ so that the probe could produce a fluorescence enhancement effect. In addition, the fluorescent probe BTD-Hg-Lyso exhibited the advantages of large Stokes shift (210 nm) and good selectivity. More importantly, the probe BTD-Hg-Lyso could be used for the determination of Hg2+ in cellular lysosomes. BTD-Hg-Lyso was able to image Hg2+ in HeLa cells, zebrafish, and tobacco seedlings (rhizome and stem) successfully.

A bifunctional fluorescent sensor based-on Pillar[5]arene for efficient detection of MnO4− as an oxidant and Hg2+ ion in aqueous media: Bio-imaging in living cells

The high amounts of oxidants and heavy metal ions caused undesirable health results and the detection of these ions gained increasing importance with new techniques. This paper focuses on a fluorescent macrocyclic sensor based on Pillar[5]arene and Bodipy (Bodipy-P[5]arene) for the recognition of oxidants and heavy metal ions in aqueous solution. After the characterization of the macrocyclic ligand, the spectroscopic measurements were carried out by Uv–vis and fluorescence spectroscopies. The bifunctional fluorescent macrocycle, Bodipy-P[5]arene, presents to a dual effect with fluorescence quenching response for fluorometrically recognizing MnO4- and Hg2+ ions. Bodipy-P[5]arene has low detection limits of MnO4- and Hg2+ such as 1.15 × 10-7 M and 8.12 × 10-7 M, respectively. Moreover, both Bodipy-P[5]arene can respectively detect the target ions in acidic and basic mediums and the macrocyclic ligand has short response times. In addition, the Bodipy-P[5]arene probe demonstrates low cellular toxicity and exceptional membrane permeability, making it a successful tool for fluorescently imaging Hg2+ and MnO4- ions within living HeLa cells.

A new aggregation-induced emission-based fluorescent probe for effective detection of Hg2+ in water, tea and seafood and its cell imaging

Mercury ion (Hg2+) is highly toxic to the environment and organisms, therefore, monitoring and quantitative detection of Hg2+ is of great significance. In this work, a new fluorescent probe TPEH that integrated tetraphenylethene (TPE) and 2-(2′-hydroxyphenyl)benzothiazole was designed and synthesised. In EtOH/HEPES (2:8, v/v, pH = 7.2) solution, TPEH displays fluorescence turn on detection of Hg2+ with the advantages of swift response (<100 s), high selectivity and strong disturbance-resistant, a large Stokes shift (220 nm), and low limit of detection (81.7 nM). The sensing mechanism was proved to be Hg2+-triggered releasing of the aggregation-induced emission (AIE)-active precursor compound 2. TPEH has been successfully applied to detect Hg2+ in seafood and tea, and image Hg2+ in living cells. In addition, TPEH can be used to detect the content of Hg2+ in actual water samples with the aid of smartphone.

An aggregation-induced emission fluorescent probe for highly sensitive and selective detection and imaging of Hg2+ in living cells

Mercury ions (Hg2+), as one of heavy transition metals (HTM), is a highly toxic metal that is hazardous to human health. Here an aggregation-induced emission (AIE) fluorescent probe is designed for the highly sensitive and selective detection of Hg2+. The probe is engineered with a tetraphenylethene (TPE) derivative as the fluorophore and thiopropionic acid as the site of recognition for Hg2+. Due to the different solubilities of the probe AIE-COOH and its corresponding product after reaction with Hg2+. The probe demonstrates a maximum detection limit of 22 nM and a fast response time of ∼100 s. Simultaneously, AIE-COOH exhibits outstanding detectivity and hypersensitivity for the detection of Hg2+ in aqueous solutions. These characteristics demonstrate that AIE-COOH hold a great potential in environmental, food and biological systems. Moreover, we have also successfully applied it to Hg2+ fluorescence imaging in in living cells.

Carbon dots as specific fluorescent sensors for Hg2+ and glutathione imaging.

Nitrogen-doped carbon dots (NCDs) have been constructedin which coal washing wastewater is used as carbon precursor, tryptophan is added for nitrogen doping and surface functional together with polyethylene glycol. The nitrogen doping and surface functional with electron rich groups resulted in excellent fluorescent properties regardingstability, reversibility, printability with high quantum yield which not only enable the NCDs as fluorescent ink for advanced message encryption, but also realize specific on-off-on fluorescent sensing of Hg2+ and GSH as solution, hydrogel and filter paper sensors. TheNCDs had a linear range of 0.01-100 μM and a detection limit of 6.27 nM (RSD 0.33%) for Hg2+ and the NCDs@Hg2+ had a linear range of 0.01-60 μM and a detection limit of 3.53 nM (RSD 1.53%) for GSH in sensing studies with aqueous solutions. In addition, with the low cytotoxicity and good biocompatibility NCDs have been successfully used for imaging Hg2+ and GSH in living MG-63 cells. The presented NCDs recycle waste coal washing water into worthwhile material which can be implemented as promising anti-counterfeiting and message encryption candidates as well as effective Hg2+ and GSH sensing, tracking and removing tools in complicated environmental and biological systems.

A new aggregation-induced emission-based fluorescent probe for effective detection of Hg2+ and its multiple applications

Detection of mercury ions (Hg2+) in actual samples is of significant importance due to the toxicity of Hg2+ to human health. In this work, a simple tetraphenylethene (TPE) derived fluorescent probe TPE-Hg based on aggregation-induced emission (AIE) mechanism was synthesized. TPE-Hg can visually recognize Hg2+ in THF/HEPES (1:9, v/v, HEPES 20 mmol/L, pH 7.3) system with rapid response, strong anti-interference ability, large Stokes shift (203 nm), and low detection limit (7.548 × 10−7 mol/L). The results show that Hg2+ triggered elimination of TPE-Hg lead to releasing of an AIE-active compound 2 is responsible to the sensing mechanism. TPE-Hg is applicable to detect Hg2+ in actual water samples and image Hg2+ in living MCF-7 cells. In addition, TPE-Hg is suitable to assay the Hg2+ level in seafood and tea samples, and it is also applicable in test strips.

A mitochondrion-targeted fluorescent probe based on ESIPT phthalimide for the detection of Hg2+ with large Stokes shift.

A novel mitochondrion-targeted Hg2+-specific fluorescent probe 1 based on ESIPT phthalimide was designed and synthesized for the first time. Owing to the blockage of the ESIPT process between the hydroxy group and the carbonyl oxygen of the imide by the diphenylphosphinothioate group, 1 was almost nonfluorescent. After reacting with Hg2+, 1 exhibited a dramatic fluorescence enhancement due to the recovery of the ESIPT process through Hg2+-induced desulfurization-hydrolysis of the diphenylphosphinothioate moiety and the cleavage of the P-O bond. 1 showed a large Stokes shift, rapid response and high sensitivity and selectivity for Hg2+ over other metal ions. Moreover, 1 was successfully employed to image Hg2+ in the mitochondria of living cells.

Recognition of Hg2+ ion in an organic semi-aqueous medium by a new napthalimide based fluorescent probe and its bioimaging applications

This work represents a napthalimide derived fluorescent sensor for the selective and sensitive detection of Hg2+ utilizing the thioacetal group as a sensing unit. The immense selectivity of 6-(4-(1,3-dithian-2-yl)phenyl)-2-(2-morpholinoethyl)-1H benzo[de]isoquinoline-1,3(2H)-dione (TNA) has been investigated in ACN: H2O (8:2) system and the rapid response towards Hg2+ was found to be 10 s. In detecting Hg2+, TNC exhibits a blue emission (λmax = 429 nm), and the limit of detection was evaluated to be 3.3 nM. The sensing mechanism describes that the Hg2+ induces colorless to blue fluorescence-enhancement at 429 nm originated from the de-thiolation of an aldehyde. This stimulates the ICT process of TNA which resulted in the enhancement in fluorescence. Moreover, the sensor ligand was effectively applied for imaging Hg2+ in E-coli live cells.

Surface engineered bimetallic gold/silver nanoclusters for in situ imaging of mercury ions in living organisms.

Chemical sensing for the sensitive and reliable detection of mercury(II) ions (Hg2+) is of great importance in environmental protection, food safety, and biomedical applications. Due to the bio-enrichment property of Hg2+ in organisms, it is particularly meaningful to develop an effective tool that can in situ and rapidly monitor the level of Hg2+ in living organisms. In this work, we report ligand functionalized gold-silver bimetallic nanoclusters with bright red fluorescence as intracellular probes for imaging Hg2+ in living cells and zebrafish. The bimetallic nanoclusters of DTT-GSH@Au/AgNCs (DG-Au/AgNCs) with strong fluorescence that benefited from the synergistic effect of Au and Ag atoms were obtained through a one-pot synthesis method, incorporating glutathione (GSH) and dithiothreitol (DTT) as the reducers and functionalized ligands. Attractively, the bright red fluorescence of DG-Au/AgNCs could be rapidly and selectively quenched by Hg2+ within 1min with a very low detection limit of 1.01nM. Additionally, DG-Au/AgNCs had a great advantage in the detection of Hg2+ in living cells and zebrafish owing to its notably strong red fluorescence at 665nm, which could avoid effectively auto-fluorescence interference from the organism. Such easily prepared bimetallic fluorescent nanoclusters would be expected to provide a noninvasive and sensitive approach in the detection of heavy metals in situ for environmental protection.

An activatable near-infrared hemicyanine-based probe for selective detection and imaging of Hg2+ in living cells and animals.

Fluorescence imaging in the near-infrared (NIR) window has great potential for clinical diagnosis and treatment because of its deep penetration and high contrast. Here, a NIR hemicyanine-based probe (CyP) was synthesized for selective detection and imaging of Hg2+ in living cells and animals. Using the rigid xanthene structure as the electron donor, trimethylindolenine as the electron acceptor and diphenylphosphinothioic chloride as the recognition element, the probe CyP could specifically respond to Hg2+ and transform into an activated donor-π-acceptor (D-π-A) motif with a NIR emission maximum at 710 nm. Cell and animal imaging experiments showed that the probe CyP could be activated by Hg2+ and had good concentration dependence in imaging. Meanwhile, animal imaging experiments showed that the activated CyP probe exhibited a higher tissue penetration depth and spatiotemporal resolution. Thus, the probe CyP could be a useful tool for monitoring and visually evaluating Hg2+ in living systems.

Gold nanocluster-based ratiometric fluorescent probe for biosensing of Hg2+ ions in living organisms.

Gold nanoclusters (Au NCs) have become a new alternative to conventional fluorescent probes in biosensing and imaging. Herein, a gold nanocluster-based nanocomplex displaying single-excitation and dual-emission fluorescence property was fabricated by the conjugation of red-emitting glutathione-protected gold nanoclusters (Au-GSH NCs) and green-emitting fluorescein isothiocyanate (FITC) molecules. The inorganic-organic nanocomplex possesses good ratiometric fluorescence sensing ability with one emission peak showing a sensitive fluorescence response towards Hg2+ ions and the other acting as the internal reference. The nanocomplex was demonstrated to have high stability, excellent biocompatibility, high intracellular penetrability and good biological imaging ability. It was employed as a sensitive nanosensor for rapid sensing and imaging of Hg2+ ions in living cells and zebrafish with high contrast.

Multiple heteroatom-doped photoluminescent carbon dots for ratiometric detection of Hg2+ ions in cell imaging and environmental applications.

Photoluminescence detection and imaging of Hg2+ ions in the biochemical living system are of great importance. In this study, a new photoluminescent probe based on nitrogen (N), sulfur (S), and boron (B) multiple heteroatom co-doped carbon dots (NSB-CDs) is synthesized for the ratiometric detection of Hg2+ ions. The prepared NSB-CDs possess good aqueous solubility, excellent pH and ionic stability, excitation dependency, and high quantum yield (QY = 17.6%). The ratiometric photoluminescent sensor NSB-CDs exhibit high selectivity, sensitivity, and interference towards Hg2+ ions over other metal ions. After adding Hg2+ ions, the emission intensity of the NSB-CDs exhibits a large redshift from 452 to 496 nm (up to 44 nm), corresponding to a notable change from blue to green emission in aqueous solutions. The association constant (Ka), the limit of detection (LOD), and the limit of quantification (LOQ) for NSB-CDs/Hg2+ complex are calculated to be 3.6 × 104 M-1, 3.1 × 10-9 M, and 10.4 × 10-9 M, respectively, in the range of 0-30 × 10-6 M. The live cell bioimaging of HCT-116 cells with NSB-CDs validates the application of multicolor imaging for the detection of Hg2+ ions in aqueous media and biological systems. Moreover, the potential use of the NSB-CDs/Hg2+ complex for real sample analysis is demonstrated.

A novel xanthene-based fluorescence turn-on probe for highly selective detection of Hg2+ in water samples and living cells

Mercury ions are highly toxic to living organisms and environment, hence Monitoring and quantification of mercury ions remain great significance. Herein, we have designed and synthesized a novel reaction-based fluorescence probe RANS for detection of Hg2+ by using a xanthene derivate as fluorophore and a thiosemicarbazide moiety as the recognition site. By applying mercury-promoted desulfurization reactions, probe RANS exhibited excellent capability of detecting Hg2+, such as rapid response (120 s), high sensitivity (0.019 μM) and good selectivity. Upon reaction with Hg2+, the thiosemicarbazide group of probe RANS formed 1,3,4-oxadiazole along with a significant color change from colorless to light green. Importantly, RANS has been successfully applied to selectively imaging Hg2+ in living cells with low cytotoxicity and quantitative detection of Hg2+ in real water samples.

A novel near-infrared fluorescence probe for detecting and imaging Hg2+ in living cells.

Fluorescence imaging, as one of the important means of biological lesion analysis, is widely used in medical analysis. To improve detection specificity, near-infrared emission fluorescent probes have been developed. Sensitive and selective near-infrared (NIR) fluorescent probes for Hg2+ , which is a heavy metal ion harmful to human health, are urgently needed to investigate the physiological toxicity of Hg2+ . The NIR fluorophore based on the traditional structure of rhodamine was prepared by introducing anthocyanin functional groups, and a rhodamine spiro ring structure was constructed to recognize Hg2+ (CCS-Hg). The probe CCS-Hg demonstrated good selectivity and high detection sensitivity for Hg2+ and the most likely mechanism was verified through theoretical calculations. We applied the probe CCS-Hg in the examination of Hg2+ distribution in living cells by NIR fluorescence imaging. This work provides a promising molecular tool for studying the toxicological effects of mercury ions in cell.

Ultra-high quantum yield nitrogen-doped carbon quantum dots and their versatile application in fluorescence sensing, bioimaging and anti-counterfeiting

The exploration of carbon quantum dots (CQDs) with ultra-high quantum yield, simple synthesis path, and satisfying output to facilitate their wide applications in numerous fields are always the research focus. In this work, nitrogen-doped carbon quantum dots (N-CQDs) with strong blue fluorescence were synthesized with a simple one-step hydrothermal method using citric acid and o-phenylenediamine as raw materials, and the absolute quantum yield was as high as 92.1%. The detailed research results demonstrate that the N-CQDs have outstanding fluorescence stability, high selectivity, and anti-interference in Hg2+ detection. The obtained N-CQDs also possess excellent biocompatibility, which can also be successfully applied in cell imaging and intracellular Hg2+ detection. Most importantly, due to their high quantum yield and excellent dispersibility, the N-CQDs solution can be used as a quick-drying fluorescent ink for ink-jet printing. Therefore, the as-prepared N-CQDs have great potential in fluorescence sensing, biomedical diagnosis, data encryption, and anti-counterfeiting.

Two Novel Fluorescent Probes as Systematic Sensors for Multiple Metal Ions: Focus on Detection of Hg2.

Many precedents prove that fluorescent probes are promising candidates for detection of metal ions in the environment and biological systems. Herein, two novel photoinduced electron transfer (PET)-based fluorescent probes, CH3-R6G and CN-R6G, were rationally synthesized by incorporating a triazolyl benzaldehyde moiety into the rhodamine 6G fluorophore. The optical properties of these probes were studied using an ultraviolet–visible (UV–vis) absorption spectrophotometer and a fluorescence spectrophotometer. Through the analysis of the test results, it is concluded that the selectivity and sensitivity of these two probes to Hg2+ are better than to other metal ions (Ag+, Al3+, Ba2+, Cd2+, Co3+, Cu2+, Cr3+, Fe3+, Ga2+, K+, Mg2+, Na+, Ni2+, Pb2+, and Zn2+). According to the standard curve diagram, the detection limits of CH3-R6G and CN-R6G were determined to be 1.34 × 10–8 and 1.56 × 10–8 M, respectively. Reaction of the probes with Hg2+ resulted in a color change of the solution from colorless to pink. The corresponding molecular geometric configuration, orbital electron distribution, and orbital energy of these two compounds were predicted by density functional theory (DFT). The two probes CH3-R6G and CN-R6G have been successfully used for imaging Hg2+ in live breast cancer cells, thereby indicating their great potential for the micro-detection of Hg2+ in vivo.

Imaging Hg2+-Induced Oxidative Stress by NIR Molecular Probe with "Dual-Key-and-Lock" Strategy.

Mercury (Hg) is considered an extremely toxic heavy metal which is extremely harmful to both the human body and environment. In addition, Hg2+-induced oxidative stress also exerts a crucial role to play in pathophysiological mechanisms of mercury toxicity. Thus, efficient and specific fluorescent probes for imaging Hg2+-induced oxidative stress are necessary. In the present study, we rationally design a novel Hg2+-activated and ICT-based NIR emission fluorescent probe NIR-HO for sequentially monitoring the ONOO- level with a "dual-key-and-lock" strategy. The probe NIR-HO showed rapid response and excellent specificity and sensitivity for the detection of Hg2+ and ONOO- in vitro. Cell imaging demonstrated that Hg2+-induced oxidative stress was involved in ONOO- upregulation. Also, GSH, NAC, and EDTA were employed as excellent detoxifying drugs against Hg2+-induced toxicity. Moreover, the probe NIR-HO was successfully used for imaging Hg2+ and ONOO- in vivo. In brief, NIR-HO provides a simple and powerful approach which can be used to image Hg2+-induced oxidative stress in the pathological environment.

A new phenothiazine‐based fluorescence sensor for imaging Hg2+ in living cells

A new phenothiazine‐based sensor PHE‐Ad for monitoring Hg2+ has been designed and synthesized based on the intramolecular charge transfer (ICT) mechanism. The probes were characterized by FTIR, 1H NMR, and HRMS, and their optical properties were detected by UV and FL. It's showed the probes detection of Hg2+ compared to other metal ions (Mg2+, Cu2+, Hg2+, Ag+, Co2+, Cr3+, Al3+, Ni2+, Zn2+, Ca2+, Fe3+, Fe2+, K+, Na+, and Cd2+) based on the test results. Besides, the detection limits were determined to be 2.12 × 10−8 M through the standard curve plot. In addition, sensor PHE‐Ad shows high selectivity and sensitivity for Hg2+ with a fast response in a suitable pH range. Furthermore, taking into account its good “turn‐on” fluorescent sensing behavior and low cell cytotoxicity, PHE‐Ad was successfully applied to detect and image Hg2+ in real water samples and living cells, which shows great potentials for application in environmental and biological systems.

Bithiophene-based fluorescent sensor for highly sensitive and ultrarapid detection of Hg2+ in water, seafood, urine and live cells.

Using Hg2+-promoted deprotection reaction, we have developed a new fluorescent turn-on sensor 2TS based on bithiophene fluorophore for Hg2+ detection. The sensing mechanism of 2TS towards Hg2+ was strongly proved by 1H NMR, FTIR, HRMS, UV-vis and fluorescence spectra. Remarkly, 2TS towards Hg2+ in 100% aqueous solution shows high sensitivity with a low detection limit of 19nM, superior selectivity and ultra-rapid response of 20s during a wide sensing pH range from 4 to 10. Taking advantage of the excellent properties, the low-cost sensor 2TS-based filter paper/TLC test strips were fabricated for visual, immediate and quantitative detection of Hg2+ in water, proving its applicability towards sensitive in-situ and on-site detection. Meanwhile, 2TS showed high analytical performance for Hg2+ detection in water, seafood as well as human urine samples. Moreover, thanks to the good water solubility, negligible cytotoxicity, good biocompatibility and cell-membrane permeability, 2TS was further applied to effectively image Hg2+ in live cells. Furthermore, the developed sensor 2TS acted as good fluorescent display material for Hg2+ with obvious color change.

Highly sensitive and selective fluorescent monomer/polymer probes for Hg2+ and Ag+ recognition and imaging of Hg2+ in living cells.

The detection of heavy metals such as Hg2+ and Ag+ is important and urgent. In this work, -NO2/-NH2/C=S boron dipyrromethene small molecular derivatives were synthesized at first. Then they were incorporated into polymer chains. The macromolecular fluorescent probes were obtained via Sonogashira reaction using the small molecular probes as building blocks. The as-prepared small-molecule fluorescent probe BO3 exhibits high sensing performance for Hg2+. By introducing it into macromolecules, the sensing ability still remains, and even more, the recognition performance is improved. The macromolecular fluorescent probes P1, P2, and P3 also have high recognition ability for Ag+ with a binding ratio of 2:1 (metal ion to probe ratio). Through the study of the sensing mechanism and the recycling experiments, it is found that the probes responded by the photo-induced electron transfer mechanism and can be recycled and reused. At the same time, BO3, P2, and P3 show excellent recognition performance for Hg2+ in living cells and zebrafish. Living cell imaging experiments indicated that these fluorescent probes had good cell membrane permeability and low cytotoxicity, and could realize bioimaging of Hg2+. Therefore, the application value of these fluorescent probes could be enlarged. Graphical abstract.