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The design of multifunctional fluorescent probe for detecting Zn2+/ ClO−/H2O and application in high-security level information encryption
... However, Cu 2+ , Hg 2+ , Fe 3+ , and Al 3+ induced quenching effects on the detection signal. Wang et al. synthesized probe 46 [87], through the reaction between 3-hydroxy-2-naphthalaldehyde hydrazone and 2-hydroxy-5-tert-butylbenzaldehyde. This probe showed a fluorescence enhancement at 530 nm upon binding with Zn 2+ , demonstrating an impressive LOD of 5.03 nM for Zn 2+ . ...
Zinc(II) ions (Zn2g) play crucial roles in the growth, propagation, and metabolism of animals, plants, and humans. Abnormal concentrations of Zn²⁺ in the environment and living organisms pose potential risks to environmental protection and human health. Therefore, it is imperative to develop rapid, reliable and in-situ detection methods for Zn2+ in both environmental and biological contexts. Furthermore, effective analytical methods are required for diagnosing diseases and understanding physiological metabolic mechanisms associated with Zn²⁺ concentration levels. Organic small-molecule fluorescent probes offer advantages such as fast, reliable, convenient, non-destructive detection capabilities and have significant application potential in Zn²⁺ detection and bioimaging; thus garnering extensive attention. Over the past two years alone, various organic small-molecule probes for Zn²⁺ based on different detection mechanisms and fluorophores have been rapidly developed. However, these probes still exhibit several limitations that need further resolution. In light of this context, we provide a comprehensive summary of the detection mechanisms, performance characteristics, and application scope of Zn²⁺ fluorescence probes since year 2022 while highlighting their advantages. We also propose solutions to address existing issues with these probes and outline future directions for their advancement. This review aims to serve as a valuable reference source offering insights into the development of advanced organic small-molecule-based fluorescence probes specifically designed for detecting Zn²⁺.
A Schiff base fluorescent probe compound H2L (N′‐(4‐bromo‐2‐hydroxy‐benzylidene)‐3‐hydroxy‐2naphthohydrazide) was synthesized using 3‐hydroxy‐2‐naphthoic acid hydrazide as raw material. The structure of H2L was characterized by NMR, IR, MS, and XRD methods. The fluorescence performance of H2L was studied by UV and FS. The results show that in 1 : 4 water system /DMSO solution (water system: 20 % triethanolamine:0.1 mol/L L‐cysteamine acid=1 : 1), H2L can be used to quickly identify Mg²⁺ with an obvious fluorescence enhancement and redshift. A color change “light green→bright yellow” can be clearly observed with the naked eye. The Mg²⁺ concentration shows a good linear relationship in the range of 0–1.0×10⁻⁵ mol/L, with a detection limit of 1.77×10⁻⁷ mol/L with good stability and reversibility. The response mechanism was explored through Job's curve, NMR titration and MS, which showed that Mg²⁺ can form a 1 : 1 complex with H2L. A gel (SAL) was prepared by doping H2L into sodium alginate (SA). SAL was found to show good adsorption properties for Mg²⁺ and can be easily distinguished by the naked eye under ultraviolet light. The microscopic morphology and composition of SAL before and after Mg²⁺ adsorption were analyzed by SEM‐EDS. H2L can be used for the qualitative detection of Mg²⁺ in actual water samples without being affected by other common metal ions, and has potential application value in the field of environmental detection.
The quantitative analysis of trace water in organic solvents has always been a research hotspot, and it is still in the development stage and needs to be continuously developed. In this study, a facile and rapid approach was developed for the preparation of carbon quantum dots (CQDs) with yellow fluorescence emission and ultrahigh absolute fluorescence quantum yields (92.6%). Compared to traditional organic fluorescent molecules, the preparation of CQDs is simpler, faster and more environmentally friendly. It is found that the fluorescent properties of CQDs are excellent in organic solvents and could be quenched by trace water, which makes them a promising material used without any modification for the detection of water in organic solvents. As a result, the as-prepared CQDs were adopted as fluorescent probes for the detection of water in organic solvents (ethanol, tetrahydrofuran, and 1,4-dioxane). The limit of detection was as low as 0.01%. To the best of our knowledge, this is the first time that CQDs have been used as water sensing fluorescent probes in organic solvents. The possible mechanism for trace water detection of the as-prepared CQDs in organic solvents is attributed to the specific water-fluorophore interaction and partially to the increase in polarity of the solvent caused by an increase in water concentration.
Selective and sensitive fluorescent probes for ClO⁻ are desirable due to the importance of ClO⁻ in biological processes. Here, a coumarin Schiff's base, compound 1, has been developed and successfully used as a one- and two-photon fluorescent probe for ClO⁻ with high selectivity. This probe can recognize ClO⁻ with obvious color change from yellow-green to colorless and green to blue fluorescence emission, which can be observed by the naked eye. The properties of low cytotoxicity and good cell permeability allow it to be used for ClO⁻ detection in living cells and zebrafish by both one- and two-photon microscopy imaging. All these results indicate that the compound is a sensitive probe with potential for analysis of ClO⁻ in biological samples. The mechanism by which probe 1 recognizes ClO⁻ is possibly nucleophilic addition followed by hydrolysis.
Selective, sensitive fluorescent probes for ClO(-) are desirable due to the importance of ClO(-) in biological processes. Herein, a readily available turn-off fluorescent probe for ClO(-) is reported, which displays highly selectivity and sensitivity over other common anions and reactive oxygen/nitrogen. Moreover, it is able to detect ClO(-) in Ramos cells via cellular imaging.
A ratiometric fluorescent probe (RMClO-2) for ClO‾ based on the conjugate of coumarin-rhodamine was presented, which could sense ClO‾ with fast response (within 5s), high sensitivity and excellent selectivity. More importantly, RMClO-2 is the first mitochondria-targeted ratiometric fluorescent probe to image exogenous and endogenous ClO‾.
Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The first part of this paper presents the most important methods of preparation of ZnO divided into metallurgical and chemical methods. The mechanochemical process, controlled precipitation, sol-gel method, solvothermal and hydrothermal method, method using emulsion and microemulsion enviroment and other methods of obtaining zinc oxide were classified as chemical methods. In the next part of this review, the modification methods of ZnO were characterized. The modification with organic (carboxylic acid, silanes) and inroganic (metal oxides) compounds, and polymer matrices were mainly described. Finally, we present possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced. This review provides useful information for specialist dealings with zinc oxide.
The essential trace element zinc (Zn) is widely required in cellular functions, and abnormal Zn homeostasis causes a variety of health problems that include growth retardation, immunodeficiency, hypogonadism, and neuronal and sensory dysfunctions. Zn homeostasis is regulated through Zn transporters, permeable channels, and metallothioneins. Recent studies highlight Zn's dynamic activity and its role as a signaling mediator. Zn acts as an intracellular signaling molecule, capable of communicating between cells, converting extracellular stimuli to intracellular signals, and controlling intracellular events. We have proposed that intracellular Zn signaling falls into two classes, early and late Zn signaling. This review addresses recent findings regarding Zn signaling and its role in physiological processes and pathogenesis.
Simple, fast, and sensitive detection of trace water in organic solvents is an urgent requirement for chemical industries. Herein, combining the unusual excited-state intramolecular proton transfer (ESIPT) mechanism with the effective strategy of pore space partition, for the first time, we construct a powerful fluorescent metal-organic framework (SNNU-301) probe with excellent water stability. The SNNU-301 probe shows a remarkable performance for turn-on ESIPT-based fluorescence response to water in nine common organic solvents, exhibiting wide linear ranges, low limit of detection values, and ultrafast response, especially in dimethyl sulfoxide (0-5.2%; 0.011%, v/v; 110 s). The typical ESIPT-sensitive linker 2,5-dihydroxyterephthalate (DHBDC) imparts it with discriminative detection properties via enol-keto tautomerism, and light-responsive triangular tri(pyridin-4-yl)-amine (TPA) realizes pore space partition. The theoretical calculation gives an in-depth explanation about the proton transfer mechanism. Comparative experiments and GCMC simulation provide evidence that the synergy of the ESIPT process and TPA of the framework further boosts its performance effectively. Definitely, this work not only offers a promising candidate with fast detection speed, high sensitivity, excellent universality, and visual observation for the determination of water in organic solvents but also provides valuable guidance for the design of high-performance fluorescent probes.
Hypochlorous acid (HClO)/Hypochlorite (ClO⁻) is not only a natural by-product of cell metabolism and participates in various physiological processes, but also as an excellent fungicide, HClO/ClO⁻ has also been widely used in daily life, providing a strong guarantee for human health. It can be seen that it is necessary to develop a reliable and efficient HClO/ClO⁻ detection and imaging method in biomedical research and disease diagnosis. Thus, a novel reactive HClO/ClO⁻ fluorescent probe TPAQ-ClO based on triphenylamine derivatives was prepared to detect HClO/ClO⁻ in vivo and in vitro. Due to the HClO-triggered the effective chemical conversion of the quinoline salt group cleavage, probe TPAQ-ClO exhibited an outstanding selectivity (LOD = 20.7 nM) and quick response to HClO/ClO⁻ in DMSO/PBS buffer (4/6, v/v) solution with large Stokes shift (205 nm). Benefiting from its excellent sensing properties, the probe TPAQ-ClO has been used in mitochondrial co-localization experiments to image endogenous and exogenous HClO/ClO⁻. In addition, due to its excellent water solubility, the probe TPAQ-ClO can also provide a new fluorescent detection idea to detect HClO/ClO⁻ in real samples.
Hypochlorite (ClO⁻), which is an important reactive oxygen species (ROS) in biology, has attracted scientific attention. Intracellular ClO⁻ are mainly produced in mitochondria. While many studies have shown that ClO⁻ can be detected in mitochondria, low background signal interference fluorescent probes for detecting endogenous ClO⁻ in mitochondria are still lacking. It is crucial to design a fluorescent probe with a large Stocks shift for rapid detection of ClO⁻ in mitochondria in this regard. In this work, we have synthesized the probe PCH that can detect ClO⁻ in the mitochondria. The probe PCH can target mitochondria and has fast response speed, high selectivity, large Stocks shift and low detection limitation. Utilizing this probe, we have been able to detect mitochondrial ClO⁻ endogenously and exogenously. According to our study results, probe PCH can be used as a satisfactory imaging tool for detecting ClO⁻ and can be used as a tool for exploring the complex physiological functions of ClO⁻.
A novel D−π−A type fluorescent probe (probe 1) was developed for water content detection in organic solvents. By analyzing the relationship between fluorescence and water content, the probe was successfully applied to determine trace water content in THF, ethyl acetate, 2‐butanone, acetone, DMF, and acetonitrile. High water contents in THF and ethyl acetate were associated with a gradual color change from yellowish green to earthy yellow. The R/G value had a linear relationship with the water content in THF and ethyl acetate. There was a linear relationship between the R/B value and water content in 2‐butanone and acetone. Furthermore, probe 1 could be used for human serum albumin (HSA) detection. Unexpectedly, the probe 1 has different color response in deuterated and non deuterated solvents, and has different fluorescence intensity and fluorescence emission wavelength. The probe 1 is rare tool that can distinguish between deuterated and non deuterated reagents.
Using 3-hydroxy-2-naphthoic acid hydrazine and 4-(diethylamino) salicylaldehyde
as raw materials, compound L with an acylhydrazones structure was synthesized. The structure of compound L was characterized by nuclear magnetic resonance spectroscopy, X-ray single crystal diffraction, Fourier transform infrared spectroscopy, and mass spectrometry. The results show that Compound L can quickly and selectively recognize zinc ions in the H2O/DMSO (V:V=3:7) solvent system. After that, the spectral performance of probe L was studied by fluorescence spectroscopy and UV-vis spectroscopy. The results show that the combination with Zn²⁺ can significantly enhance the fluorescence intensity of probe L while being almost unaffected by other coexisting ions. After that, Job’s curve method, nuclear magnetic titration analysis, and mass spectrometry were used to study the binding mechanism of probe L and Zn²⁺. The results showed that probe L coordinated with Zn²⁺ is 1:1. The linear equations of different concentrations of Zn²⁺ and fluorescence intensity were obtained by fitting, and the detection limit of probe L for Zn²⁺ was determined to be 6.75×10⁻⁹ mol/L. The experimental study of standard addition and recovery showed that probe L could be used for the quantitative detection of Zn²⁺ in natural water samples. After that, we prepared L-doped sodium alginate hydrogel (SAL). The research results show that SAL has obvious adsorption capacity for Zn²⁺ in solution, and the color change before and after adsorption can be easily distinguished by the naked eye under ultraviolet light. SEM-EDS study showed that the microscopic morphology and composition of SAL changed significantly before and after adsorption. This fluorescent probe can be used for detection and removal of Zn²⁺ in aqueous solution. Also, probe L is effective for sensing for zinc (II) in living tumor cells. Overall, this work allows us to obtain a great potential to be applied to detect and remove Zn²⁺.
We have designed and synthesised a novel fluorescent probe with a tetraphenylethylene (TPE) scaffold as an active fluorescent unit and thiosemicarbazide (TSC) group as a recognition unit. The probe, TPE–TSC, exhibited superior selectivity towards hypochlorite (ClO⁻) with a low limit of detection (2.0 nM). It also demonstrated a turn-off response for a brief period (<30 s) via an oxidation reaction. Furthermore, high-resolution mass spectrometry (HRMS) revealed that TPE–TSC reacted with ClO⁻ by forming a carboxylic acid moiety in nearly 100% aqueous environments. More significantly, the probe detected ClO⁻ in disinfectant, spiked milk samples, and spiked water samples. In all, TPE–TSC proposes an optimistic approach precisely for the determining the quality of milk and water contaminated with ClO⁻ and trace amounts of ClO⁻ in disinfectants.
Hypochlorous acid (HOCl), a kind of reactive oxygen species (ROS), is involved in numerous lysosomal functions. Abnormal excess or deficiency of HOCl in lysosome could not only disrupt control of apoptosis, but also relates to numerous neurodegenerative diseases. However, monitoring the subtle concentration change of lysosomal HOCl in vivo is limited. Herein, a highly sensitive ratiometric fluorescent probe (NAP-RS) was rationally designed for measuring lysosomal HOCl fluctuations. NAP-RS provides a clear ratiometric fluorescence response to HOCl with large emission gap (186 nm), rapid maximum response time (<3 s) and ultrasensitivity (limit of detection = 36 nM) at biologically-relevant concentrations. In addition, NAP-RS can be efficiently employed to visualize exogenous and endogenous lysosomal HOCl. As a matter of fact, this work will provide a new way for the improved measurement of lysosomal HOCl, and a general molecular design methodology for the facile preparation of more refined fluorescent probes.
Reactive oxygen species (ROS) and nitrogen species (RNS) are very important in various pathological and physiological processes. In particular, hypochlorous acid/hypochlorite (HOCl/OCl⁻) is one of the most important reactive oxygen species (ROS), which is endogenously produced from H2O2 and Cl⁻ by myeloperoxidase (MPO) catalysis. HOCl is both beneficial and harmful to living species including humans. HOCl can destroy invasive bacteria as an immune defense system while, on the other hand, it can cause many diseases including cancers due to pathogenic oxidative stress injury. Accordingly, fluorescent imaging probes for HOCl have been actively investigated in recent years. In this review, we cover the recent progress from 2019 to 2021 on small molecule-based fluorescent imaging probes for hypochlorous acid (HOCl)/hypochlorite (OCl⁻).
A benzothiazole-based fluorescent and colorimetric chemosensor BZD ((E)-2-(benzo[d]thiazol-2-yl)-5-((4-(diethylamino)-2-hydroxybenzylidene)amino)phenol) was applied for detecting ClO⁻. BZD showed fluorescence quenching and color variation for ClO⁻ via oxidative reaction between ClO⁻ and the imine bond. It could effectively detect ClO⁻ over various competitive analytes. Detection limit for ClO⁻ was calculated to be 1.74 μM by fluorescent method and 16.44 μM by colorimetric one, respectively. Additionally, BZD could be utilized for sensing ClO⁻ in zebrafish, real water sample and paper strip. The photophysical characteristics and sensing mechanism of BZD to ClO⁻ were studied by fluorescent and UV-visible spectroscopy, NMR titration, and ESI-mass spectrometry.
In this work, a bifunctional peptide-based fluorescent probe L containing a tetrapeptide scaffold (Pro-Gly-His-Trp-NH2) and a dansyl group was synthesized using solid phase peptide synthesis (SPPS) technology. As designed, L, based on a FRET mechanism, exhibited high selectivity, excellent ratiometric signals, and fast response to Zn²⁺ in aqueous solutions at an excitation wavelength of 280 nm. In addition, when excited at 320 nm, L exhibited a fluorescent “turn-on” response towards Zn²⁺ based on PET mechanism. More importantly, the stoichiometry of L and Zn²⁺ was determined to be 2:1 by fluorescent titration, Job’s plot method, and ESI-MS spectrometry. The association constant for Zn²⁺ ions was determined to be 6.26×10⁸ M⁻², while the limit of detection (LOD) of L was estimated as 5.43 nM, which is a much lower value than WHO and EPA guidelines for drinking water. Moreover, L was successfully applied to detect both Zn²⁺ and Cu²⁺ in living cells due to good biocompatibility and excellent low toxicity.
A novel Schiff base fluorescent probe (N'-(4-(diphenylamino)benzylidene)-3-hydroxy-2-Naphtho-hydrazide)(L) was designed and synthesized using 3-hydroxy-2-naphthoic acid hydrazide and 4-diphenylaminobenzaldehyde as raw materials. The structure of L was characterized through ¹H NMR, ¹³C NMR, HR-MS, IR and X-ray. The study found that probe L showed high sensitivity and selectivity response to copper ions(Cu²⁺) in H2O/DMSO(V:V=3:7, pH=7) solution. The possible mechanism of coordination between L and Cu²⁺ was studied by HR-MS, ¹H NMR and DFT calculation. PAML was prepared by the method of doping L into polyacrylamide(PAM). PAML had high adsorption of Cu²⁺ and the removal rate of Cu²⁺ by PAML in water reached 96.99%, in addition, the color change could be distinguished by naked eyes under UV lamp. The microscopic morphology of PAML before and after adsorption of Cu²⁺ was observed by SEM-EDS.
A bis (thiosemicarbazone) based probe has been synthesized and structurally characterized. The probe exhibits good selectivity towards Zn(II), Cd(II) and Hg(II) ions in an aqueous solution containing 95% water with ratiometric fluorescence changes. The modes of coordination of the probe with these metal ions and binding properties have been examined using different spectral techniques. The binding constants, determined using fluorescence titration data, are found to be 9.8 × 10³, 1.39 × 10⁵ and 2.03 × 10¹³ M⁻¹, respectively for Zn(II), Cd(II) and Hg(II) complexes. The high sensitivity of the probe has been demonstrated by the very low limit of detection i.e. 5.1, 3.4 and 0.51 μM for Zn(II), Cd(II) and Hg(II) ions, respectively. Different coordination mode of these metal ions with the probe has resulted in varying intra-ligand fluorescence (λem nm, Zn(II): 488, Cd(II): 470 and Hg(II): 578) among these metal complexes.
A novel naphthol-naphthalimide-based fluorescent chemosensor CGB (N-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-3-hydroxy-2-naphthamide) for ClO⁻ was synthesized. Sensor CGB can detect ClO⁻ by a fluorescent turn-on method. The detection limit is calculated to be 10.67 μM. CGB showed a remarkable selectivity for ClO⁻ over diverse competing anions including reactive oxygen species (ROS) via deprotonation reaction. Additionally, sensor CGB was well applied as a fluorescent test kit for the determination of ClO⁻. Sensing mechanism of CGB to ClO⁻ was demonstrated by fluorescent and UV–vis spectroscopy, ESI-mass, NMR titration and DFT calculations.
The pH and water content in organic solvents are some of the most important parameters that play a key role in chemical laboratories, clinical analysis, food processing, biomedical and environmental monitoring, and life sciences. Herein we are reporting on the design, synthesis and sensor activity of a novel 4-amido-1,8-naphthalimide ratiometric fluorescent pH probe based on excimer-monomer switching mechanism. The fluorescence chemosensing behavior of the synthesized compound was studied in solvents of different polarity and the results obtained clearly demonstrates the great opportunity of the novel probe selectively to determine pH in aqueous solutions and water content in organic environment.
Naphthalimide-decorated fluorinated acetamides 1 and 2 were developed as solvent-sensitive dual emissive fluorescence probes. Particularly, 1 exhibited dual emission with a large Stokes shift for water, DMF, and DMSO solvents over other various organic solvents. The dual emission might be due to the increase of intramolecular charge transfer (ICT) of the naphthalimide moiety through the association of the difluorinated acetamide group with the solvent molecules. The 1 can give rise to a ratiometric change in the dual emission and a visual fluorescent color change depending on the water contents in organic solvents, including ethanol, methanol, acetonitrile and DMF solvents. Moreover, the 1-impregnated paper strips showed a rapid and easy-to-visualize fluorescent color change enabling water detection in organic solvents. These simple-to-use paper strips were also found to be reusable over 20 times.
Aerogel is a kind of gel materials, of which the fluid phase is gas. Aerogel has the characteristics of low density and high porosity, and has a wide application prospects. In this work, a rapid solvents exchange method was developed, and using in-situ secondary extraction, rapid solvents exchange in aerogel preparation was achieved through the miscibility and immiscibility of ethanol-dichloromethane-water. Combined with hydrophobic treatment and vacuum drying, hydrophobic silica aerogel was obtained. The aerogel had a low density and a contact angle with water of 155.8°. The aerogel can load various organic fluorescent probe dyes, which can effectively avoid the fluorescence quenching caused by the aggregation of the probe molecules, which it will expand the practical application range of the organic fluorescent probes in wider fields.
Although current high-energy-density lithium-ion batteries (LIBs) have taken over the commercial rechargeable battery market, the increasing concerns about limited lithium resources, high-cost, and insecurity of organic electrolyte scale up limit their further development. Rechargeable aqueous zinc-ion batteries (ZIBs), the alternative battery chemistry, have paved the way not only for realizing environmentally benign and safe energy storage devices, but also reducing the manufacturing costs of next-generation batteries. This review underscores recent advances in aqueous ZIBs; these include the design of high reversible Zn anode, optimization of electrolyte, and a wide range of cathode materials and their energy storage mechanisms. We also present recent advanced techniques that aim at overcoming the current issues in aqueous ZIBs system. This review on the future perspectives and research directions will provide a guide for future aqueous ZIBs study.
A novel fluorescence chemosensor M1 was designed and synthesized through Knoevenagel condensation reaction between 2-(4-naphthalen-1-yl-phenyl)-2H-[1,2,3]triazole-4-carbaldehyde and malononitrile. UV–vis absorption and fluorescence emission spectroscopy found that M1 possessed intramolecular charge transfer (ICT) and aggregation-induced emission enhancement (AIEE) properties. Because M1 contained dicyano-vinyl groups which can easily occurred the nucleophilic Michael addition of cyanide anion. So M1 exhibited remarkable selectivity and sensitivity toward CN⁻ with a low detection limitation of 3.91 × 10⁻⁸ M. The mechanism with cyanide anion was systematically studied by ¹H NMR titration experiments and HR-MS.
A naphthalene-based two-photon fluorescent probe for thiophenols has been reported in this work. The probe can be applied to the quantification of thiophenols with a linear range covering from 2.0 × 10−8 to 7.0 × 10−6 mol·L−1. It exhibited a high selectivity and excellent sensitivity with a detection limit of 9.6 nM. Moreover, it was successfully used for practical detection of thiophenol in water samples with a good recovery, and two-photon imaging of thiophenol in live cells and tissues at a depth of 40–155 μm.
The recent developments in the field of hot dip zinc coating are reviewed with special reference to different industrial applications. The improvements in physical and chemical structural composition due to pre- and post-modification processes are discussed. The present review has the focus mainly on the readership of young researchers engaged in this field. Very recent developments on the hot dip galvanization processes are highlighted. Their industrial competencies with aluminium dipping are also briefly discussed. The scopes for immediate future developments are also highlighted then and there.
The presence of water induces a strong fluore-scence quenching of 8-HQ by the mechanism of radiation-less relaxation. More recently, the origin of ‘on-off’ typefluorescent behavior of 8-HQ containing chemosensors wasinvestigated in terms of PPT (photoinduced proton transfer)and PET (photoinduced electron transfer) processes.
The generation of zinc and zinc alloy coatings on steel is one of the commercially most important processing techniques used to protect steel components exposed to corrosive environments. From a technological standpoint, the principles of galvanizing have remained unchanged since this coating came into use over 200 years ago. However, because of new applications in the automotive and construction industry, a considerable amount of research has recently occurred on all aspects of the galvanizing process and on new types of Zn coatings. This review will discuss the metallurgy of zinc-coated steel from a scientific standpoint to develop relationships to practical applications. Hot-dip zinc coating methods, i.e. batch and continuous processes, will first be reviewed along with Fe–Zn phase equilibria and kinetics. Commercially, the addition of aluminum to the zinc bath results in three important types of coatings, galvanized, galfan and galvalume, and produces complex reactions at the coating/substrate interface. Fe–Zn–Al equilibrium will be reviewed in the light of recent studies of solubility and inhibition layer formation and breakdown. The effect of steel substrate composition on these reactions will also be critically analyzed. The overlay coating formation, or the coating alloy, is specifically chosen for its desired properties. The morphology of the galvanize, galfan and galvalume coating overlays will be reviewed, as well as the effect of heat treatment to produce a galvanneal coating. Finally, the effect of the microstructures of these coatings on the important properties of corrosion, formability, weldability and paintability will be discussed.
Oxidative stress induced by reactive oxygen species (ROS) plays crucial roles in a wide range of physiological processes and is also implicated in various diseases, including cancer, chronic inflammatory diseases and neurodegenerative disorders. Among the various ROS, hypochlorous acid (HOCl) plays as a powerful microbicial agent in innate immune system. The regulated production of microbicidal HOCl is required for host to control the invading microbes. However, as a result of the highly reactive and diffusible nature of HOCl, its uncontrolled production may lead to an adverse effect on host physiology. Because of its biological importance, many efforts have been focused on developing selective fluorescent probes to image ROS. However, it is still challenging to design a fluorescent probe with exclusive selectivity toward a particular member of ROS. In the current work, we designed FBS as a new fluorescent HOCl probe which has high selectivity, sensitivity and short response time in a broad range of pH. Compared with other sensors, the "dual-lock" structure of FBS has an advantage of eliminating interferes from other ROS/RNS. Importantly, we further showed that our HOCl probe could be applied for the in vivo imaging of physiological HOCl production in the mucosa of live animals. This probe provides a promising tool for the study of HOCl production.
BACKGROUND: Hole-transport layers (HTLs) play a crucial role in multilayer polymeric light-emitting diodes (PLEDs) for the achievement of satisfactory device performance. During the fabrication of multilayer PLEDs via solution processing, the fabricated HTLs encounter the risk of erosion during the film-forming process of subsequent emitting layers (EMLs). In contrast to the widely investigated crosslinkable HTLs, much less attention has been paid to the preparation of polar-solvent-soluble HTLs, which is a straightforward solution to overcome the interfacial mixing between HTLs and EMLs during solution processing.
RESULTS: Alternating triphenylamine- and fluorene-based anionic copolymer poly[9,9-bis(4′-sulfonatobutyl)fluorene-alt-N-(p-trifluoromethyl)phenyl-4,4′-diphenylamine]sodium salt (PFT-CF3) was synthesized via a palladium-catalyzed Suzuki coupling reaction. This polyelectrolyte is soluble only in polar solvents such as methanol, dimethylformamide and dimethylsulfoxide rather than in non-polar solvents such as toluene, chloroform and xylene. The relatively high HOMO (−5.22 eV) and LUMO (−2.26 eV) levels of this polymer endow it simultaneously with good hole-transporting and electron-blocking capabilities. The performance of red-, green- and blue-emitting devices utilizing this polyelectrolyte as HTL was investigated.
CONCLUSION: The anionic conjugated polyelectrolyte based on triphenylamine and fluorene, PFT-CF3, can serve as a promising hole-transporting/electron-blocking layer in multilayer PLEDs. Copyright
Novel ratiometric fluorescent cysteine probes based on naphthalene–thiourea–thiadiazole (NTTA) fluorescent organic nanoparticles (FONs) were designed and synthesized. NTTA FONs show good water solubility, high selectivity for sensing and a 74 nm red-shift of fluorescence emission upon binding cysteine in aqueous media are observed. Under optimum condition, linear relationships are found between the relative fluorescence intensity ratio I430/I356 and the logarithmic concentration of cysteine in the range of 0–100 μM with the detection limit was found to be 1.5 × 10−9 M, while the FL intensity of NTTA FONs to other amino acids is negligible. The possible mechanism is discussed.
Micro water content in aprotic solvents can be conveniently determined from the Stokes' shift value of the fluorescent anionic Pb(4)Br(11)(3-) cluster in situ formed in the test solvents.