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The existing strategies for myocardial infarction therapy mainly focus on reinstating myocardial blood supply, often disregarding the intrinsic and intricate microenvironment created by elevated levels of reactive oxygen species (ROS) that accompanies myocardial infarction. This microenvironment entails cardiomyocytes apoptosis, substantial vascular cell death, excessive inflammatory infiltration and fibrosis. In such situation, the present study introduces a zinc-based nanozyme injectable multifunctional hydrogel, crafted from ZIF-8, to counteract ROS effects after myocardial infarction. The hydrogel exhibits both superoxide dismutase (SOD)-like and catalase (CAT)-like enzymatic activities, proficiently eliminating surplus ROS in the infarcted region and interrupting ROS-driven inflammatory cascades. Furthermore, the hydrogel's exceptional immunomodulatory ability spurs a notable transformation of macrophages into the M2 phenotype, effectively neutralizing inflammatory factors and indirectly fostering vascularization in the infarcted region. For high ROS and demanding for zinc of the infarcted microenvironment, the gradual release of zinc ions as the hydrogel degrades further enhances the bioactive and catalytic performance of the nanozymes, synergistically promoting cardiac function post myocardial infarction. In conclusion, this system of deploying catalytic nanomaterials within bioactive matrices for ROS-related ailment therapy not only establishes a robust foundation for biomedical material development, but also promises a holistic approach towards addressing myocardial infarction complexities. Myocardial infarction remains the leading cause of death worldwide. However, the existing strategies for myocardial infarction therapy mainly focus on reinstating myocardial blood supply. These therapies often ignore the intrinsic and intricate microenvironment created by elevated levels of reactive oxygen species (ROS). Hence, we designed an injectable Zn-Based nanozyme hydrogel with ROS scavenging activity for myocardial infarction therapy. ALG-(ZIF-8) can significantly reduce ROS in the infarcted area and alleviate the ensuing pathological process. ALG-(ZIF-8) gradually releases zinc ions to participate in the repair process and improves cardiac function. Overall, this multifunctional hydrogel equipped with ZIF-8 makes full use of the characteristics of clearing ROS and slowly releasing zinc ions, and we are the first to test the therapeutic efficacy of Zinc-MOFs crosslinked-alginate hydrogel for myocardial infarction. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and synthesis of dinitrophenyl and NBD platforms based fluorescent probes 1 and 2. • Highly selective and sensitive detection of Zn2+ in aqueous solution. • Extensive DFT simulations studies both on unbound and Zn2+ bounded sensors. • The formation of probes-Zn2+ complexes validated by both FT-IR and 1H NMR. • The LODs of 1 and 2 are 124 nM and 1.06 µM, respectively. The design and synthesis of two new fluorescent probes based on dinitrophenyl (1) and 7-nitrobenz-2-oxa-1,3-diazole (2) platforms is reported. Both probes, containing bis(pyridin-2-ylmethyl)amine as a receptor unit can efficiently detect zin ions (Zn2+) in aqueous solution, with limit of detections of 124 nM and 1.06 µM, respectively. Probe 1 and 2 led to 3-fold and 2.4-fold fluorescent enhancements, respectively, with the addition of Zn2+ which suggested that working mechanism of these probes is based on the inhibition of the photoinduced electron transfer from the electron donating receptor towards the excited fluorophore. Studying binding stoichiometry by job's plot suggested 1:1 complexation between the probe and Zn2+. Moreover, the formation of probes-Zn2+ complexes was validated by both FT-IR and 1H NMR wherein marked changes in the absorption frequencies as well as distinct downfield shifts in the resonance peaks of pyridine function along with the CH 2 group linked directly to the tertiary nitrogen of the DPA unit were observed. Density functional theory (DFT) calculations suggested that the electronic density of the HOMO in 1 was concentrated on the linker between DPA and dinitrophenyl, whereas the density of the LUMO was concentrated on dinitrophenyl moiety. Upon Zn2+ binding, the electronic density in HOMO and LUMO become more delocalized. However, in case of probe 2 the delocalization of electronic density does not appreciably occur. Based on DFT simulations, both sensors form thermodynamic stable complexes with Zn2+ ions. However, sensor 2 exhibited slightly better binding preference toward Zn2+ as compared to 1. The PET based probes exhibited good selectivity to detect Zn2+ in the presence of a variety of competing metal cations. These sensors have higher sensitivity and would be able to detect chronic level of Zn2+ in the freshwater (>1.84 μM) as permitted by the US EPA. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly sensitive Zn2+ and PPi sensor LP was synthesized based on bicarboxaminoquinoline. • LP showed well water solubility, the low LOD, fast response time, and wide linear range for sensing Zn2+ and PPi. • The INHIBIT logic gate was constructed by using the reversibility of LP. • LP was applied for the detection of Zn2+ and PPi in two real water samples and cells imaging. A new ratiometric fluorescent sensor (LP) based on bicarboxaminoquinoline was designed and synthesized for sequentially recognizing Zn2+ and PPi. In aqueous solution, LP exhibited the ratiometric fluorescence response towards Zn2+, along with the about 4-folds enhancement of fluorescence quantum yield. Subsequently, the LP -Zn2+ complex displayed the fluorescence recovery upon adding PPi through the displacement strategy. And the LODs of LP and its Zn2+ complex for sensing Zn2+ and PPi were found to be 15 nM and 5.5 nM, respectively. Notably, the reversibility of LP for sequentially sensing Zn2+ and PPi had been employed to construct the INHIBIT logic gate. Moreover, LP and its Zn2+ complex had been successfully utilized for the detection of Zn2+ and PPi in two real water samples and cells imaging. [ABSTRACT FROM AUTHOR]

A straightforward methodology was employed for the self-reinforcement of zinc ions (Zn+2) within the polyelectrolyte complexation of xanthan gum (XG) and chitosan (CS) using D (+)-glucuronic acid-δ-lactone (GDL) as an acidifying agent in aqueous environment. The self-reinforcement and polyelectrolyte complexation between XG and CS was primarily achieved by maintaining acidic conditions through the use of GDL. GDL produces H+ ions, not only in converting ZnO to Zn+2 ions but also in facilitating the polyelectrolyte complexation between XG and CS. The confirmation of Zn+2 self-reinforcement was evident through the disappearance of ZnO, as observed in Fourier transform infrared spectroscopy and X-ray diffraction patterns. The compressive properties of self-reinforced Zn+2 within XG-CS hydrogels were evaluated, and their compressive strength was found to depend significantly on the reinforcement of ZnO nanoparticles. Incorporating 1 wt% ZnO improved the compressive strength of the hydrogels, decreasing further with an increasing amount of ZnO (3 wt%), as confirmed by compressive analysis. Detailed SEM images conclusively demonstrated The hydrogels porous structure, and elemental analysis verified the presence of Zn+2 ions. The antibacterial activity of Zn+2 reinforced XG-CS hydrogel showed excellent antibacterial activity towards both positive and negative bacteria. Furthermore, the biocompatibility analysis was assessed through an in vitro study that confirmed good biocompatibility towards NIH3T3 fibroblast cells. Thus, a robust inhibitory effect of bacterial growth and biocompatibility of developed hydrogels hold promise in advanced wound dressings for infected wounds. [Display omitted] [ABSTRACT FROM AUTHOR]

The increasing prevalence of antimicrobial resistance (AMR), particularly among Gram-negative organisms, has led to a significant challenge in treating infections with antibiotics. Despite the long-term efforts to explore antibacterial agents or drugs, potentiating antibacterial activity while minimizing toxicity to human health remains a significant challenge. In this study, zinc-kaolinite composites were prepared using the calcination method to achieve effective and selective antibacterial activity while maintaining non-toxicity to mammalian cells. The interfacial interactions between kaolinite and zinc ions resulted in the immobilization of the latter by cation-π interaction and polar interactions. This led to a disordered structure and different geometrical configurations at the interface, with the spatial coefficient of the zinc ions changing from 0.64 to 2.08. Furthermore, the interfacial interactions regulate the intrinsic mobility and dissolution rates of zinc ions in solution, resulting in the controlled release of zinc ions. Moreover, a well-oriented structure and steady-flow rheological behaviors enable zinc-kaolinite composites to search for bacteria, thereby achieving selective antibacterial activity. The release behavior of zinc ions at the site of the bacterial surrounding environment significantly reduces toxicity and side effects. The comprehensive investigation of interfacial interaction and antibacterial performance provides new perspectives for the development of metal ion-based antibacterial materials in public health environments. Zinc ion diffusion is controlled by interfacial interactions of nanoclay-metal ions for high delivery and selectivity, continuous action over long contact times, reduced toxicity, and efficient antimicrobial activity. [Display omitted] • The controlled release of zinc ions was achieved by interfacial interactions. • The kaolinite particles in solution could form a well-oriented network in space. • The antibacterial activity was affected by the geometrical and rheological behaviors. • The selectivity was achieved by double-layer forces with no toxicity to mammalian cells. [ABSTRACT FROM AUTHOR]

Lead and zinc ions in water are very unfriendly to humans and the environment. In this experiment, an environmental friendly and hydroxyl-rich biomass materials loofah (LG) was modified by epichlorohydrin and iminodiacetic acid (IDA). IDA-LG was used to remove Pb2+ and Zn2+ as model pollutants. X-ray photoelectron spectroscopy, scanning electron microscopy, etc were used for characterizing the prepared adsorbent. The results suggested that the adsorbent had a non-mesoporous structure while IDA modification was successful. The effects of pH, salinity, temperature and time on adsorption were investigated through batch adsorption experiments. High acidity and salinity have negative effects on adsorption. The theoretical adsorption capacity of IDA-LG for Pb2+ and Zn2+ could reach 82.5 and 25.2 mg g–1 at 303 K, respectively. Mechanism of adsorption was coordination and ion exchange. In the binary system, there was higher affinity about IDA-LG for Pb2+. There was good regenerative property of spent IDA-LG. IDA-LG could be used as a novel adsorbent to remove heavy metals from the sewage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probe NA has lower detection limit (7.52 × 10−9 M). • Stable exist in pH (2–10), capable of detecting Zn2+ in complex environments. • Real-time monitoring of Zn2+ in organisms (HUVEC cells and live mice). • Qualitative and quantitative detection of Zn2+ concentration in food and drugs. Zinc is one of the essential trace elements in the human body and plays an extremely important role in physiological processes. Therefore, it is necessary to develop a detection method that can be used for real-time, highly sensitive response of Zn2+ in organisms and has low toxicity. In this work, a novel fluorescent probe NA for Zn2+ detection based on 1,8-naphthalene dicarboxylic anhydride and dimethylpyridine amine was synthesized. Probe NA has specific recognition and real-time monitoring functions for Zn2+. Based on Job's plotting curve, it is inferred that the coordination ratio between probe NA and Zn2+ is 3:1, forming a complex of [Zn(NA) 3 ]2+. The [Zn(NA) 3 ]2+ exhibits obvious yellow fluorescence at 550 nm. Probe NA can achieve quantitative detection of Zn2+ with a detection limit of 7.52 × 10−9 M, with high selectivity and anti-interference ability. Probe NA can stably exist in a wide pH range (2–10). This indicates that it can detect Zn2+ in complex environments. In addition, based on the low cytotoxicity, high sensitivity, and real-time monitoring characteristics of probe NA, we have expanded it to real-time monitoring of Zn2+ in organisms (HUVEC cells and live mice), as well as qualitative and quantitative detection of Zn2+ concentration in food and drugs. [ABSTRACT FROM AUTHOR]

Zinc-ion batteries have attracted significant attention for practical energy storage because of their uniqueness in terms of high capacity, safety and low cost. However, due to the instability of electrodes, large-scale practical applications are challenging. 3D electrodes with high porosity and specific surface area provide an opportunity to solve these problems, increasing their stability, energy density and mechanical properties. Herein, an ultrapressure-resistant self-supporting SiOC@Cu 2 Se 3D cathode was fabricated and applied in aqueous zinc-ion batteries. The battery with the as-obtained cathode delivers a maximum compressive strength of 89.23 MPa and a toughness up to 16453 kJ m−3. In addition, the structural electrodes possess a specific capacity of 2.9 mWh cm−3 at a current density of 4.88 mA cm−3, demonstrating excellent deformation resistance and high specific capacity. Ex situ XRD and EDS show an interesting Cu 2 Se to Cu 2 O transformation during the first charge and discharge cycle. As expected, the electrode prepared in this paper provides a novel idea to manufacture 3D structured zinc-ion batteries with high specific capacity and excellent deformation resistance, fulfilling the demand for energy storage in astronautic industries and space exploration facing shock and high-pressure environments. [ABSTRACT FROM AUTHOR]

We have designed and synthesized a new luminescent mononuclear samarium (III) complex Sm - 2 h based on the [1 + 1] Schiff-base macrocycle H 2 L2 h , derived from the cyclocondensation reaction between dialdehyde and diamine precursors, and its exact architecture is determined to be [Sm(HL2 h) (NO 3) 2. The sensing ability of complex Sm - 2 h is carefully evaluated for various common inorganic ions in solution. It is shown that complex Sm - 2 h is a multi-responsive fluorimetric sensor with high selectivity for F− and PO 4 3− anions together with Zn2+ cation. The sensing process is rapid within 60 s for F− and PO 4 3− ions and 300 s for Zn2+ ion. Further detailed responsive investigations suggest that its sensing behavior has excellent linear relationship between the fluorescence intensity (or absorption value) and ion concentration. The limit of detection (LOD) for sensing F−, PO 4 3− and Zn2+ ions are as low as 2.61 μM (2.94 μM), 1.92 μM (1.64 μM) and 5.67 μM (3.53 μM), respectively, verified by fluorimetric (or colorimetric) titration experiments. ESI mass spectra prove that these efficient detections originate from the structure collapse of sensor Sm - 2 h because of the ion-induced imine bond breakage. Moreover, sensor Sm - 2 h shows excellent sensing performances for F−, PO 4 3− and Zn2+ ions in real water samples, and we also have developed a convenient method to detect these three ions by use of the sensor impregnated test paper strips, providing rapid and distinguishable fluorimetric color changes. Therefore, the macrocyclic Sm(III) complex Sm - 2 h could be regarded as a valuable candidate for monitoring F−, PO 4 3− and Zn2+ ions in practical applications. Image 1 • Luminescent macrocyclic Sm(III) complex Sm - 2 h was prepared by the template method. • Sm - 2 h was a multi-responsive fluorescent sensor for F−, PO 4 3− and Zn2+ ions. • Efficient responses originated from the ion-induced imine bond breakage in Sm - 2 h. • Test strips offered a convenient way to detect three ions, even in water samples. [ABSTRACT FROM AUTHOR]

Recently, biopolymer-based non-traditional luminogens had attracted a great deal of interest because of their potential applications in biomedical field. Herein, we report for the first time that carboxymethyl chitosan (CMCh) can exhibit strong blue fluorescence at λ = 436.8 nm when brought in contact with zinc ion (Zn2+) in both solution and hydrogel states. The resultant CMCh-Zn sample exhibits a typical fluorescence lifetime of 3.68 ns and a quantum yield of 6.8%. The fluorescence behaviors of CMCh-Zn samples at different excitation wavelengths, CMCh concentrations, temperature, and pH values, are also investigated. The results clearly indicate clustering-triggered emission characteristic of the CMCh-Zn. In order to further elucidate the chemical nature of this new fluorescence system, a series of CMCh-Zn samples are characterized by using ultraviolet-visible spectrometer, Fourier-transform infrared spectrometer and X-ray diffractometer. The data suggest that the metal-ligand complexation of CMCh with Zn2+ account for the generation of such an enhanced fluorescence. • Carboxymethyl chitosan shows blue fluorescence when mixed with Zn2+ and Cd2+ ions. • CMCh-Zn samples exhibit enhanced fluorescence in both solution and hydrogel states. • CMCh-Zn's fluorescence is explained by clustering-triggered emission mechanism. [ABSTRACT FROM AUTHOR]

Both of hypochlorous acid (HOCl) and Zn2+ ions play important roles in fundamental biological processes. They not only simultaneously exist in the biological organisms, but also coexist in the environment. Thus, developing a novel method for simultaneous detection of HOCl and Zn2+ is very necessary. Herein, the nitrogen- and sulfur-codoped carbon dots (N,S-CDs) were synthesized through a simple and rapid microwave method, it emits dual-emission fluorescence centered at 452 nm and 685 nm, which has specific recognition to HOCl and Zn2+, respectively, and they do not interfere with each other. A dual-emission and dual-response fluorescent probe was thus developed for the simultaneous detection of HOCl and Zn2+ in the environment and fluorescence imaging in the zebrafishes. The limits of detection for HOCl and Zn2+ are 27.0 nM and 13.0 nM, respectively. It has been successfully applied for the simultaneous determination of HOCl and Zn2+ in real water samples. The sensing mechanisms of the N,S-CDs to HOCl and Zn2+ were also discussed in detail. Moreover, the fluorescent probe not only can be used to real-time dynamic monitoring of HOCl and Zn2+ in the zebrafishes, but also can be applied to evaluate the oxidative stress in the zebrafishes induced by pollutions via fluorescence imaging. This work provided a new strategy for developing multifunctional fluorescent probes, and a potential application prospect for environmental monitoring and evaluating the health risks of environmental pollutants to organisms. [Display omitted] • Dual-response carbon dots for fabricating multifunctional fluorescence probe. • Simultaneous determination of HOCl and Zn2+ in real environmental water samples. • Real-time dynamic monitoring of HOCl and Zn2+ in the zebrafishes. • Evaluating the oxidative stress in the zebrafishes induced by pollutions via fluorescence imaging. [ABSTRACT FROM AUTHOR]

Zinc oxide-coated zeolite (ZOCZ) and zinc oxide (ZnO) were compared in terms of their effectiveness in removing Staphylococcus aureus (S. aureus) from nutrient broth and phosphate-buffered saline (PBS) solution. ZOCZ was found to be extremely efficient in removing S. aureus. ZnO initially was much less effective. Photographs of removal S. aureus from PBS solution with ZOCZ confirmed that a multilayer of S. aureus cells forms on the surface of ZOCZ particles. The comparison of the images of confocal laser scanning microscope and inverted contrast fluorescence microscope further proved that a multilayer of S. aureus cells formed on the surface of ZnO-30N-zeolite. The FESEM images showed that the cell membranes of S. aureus attached to the surface of ZnO-30N-zeolite collapsed. Energy Dispersive X-Ray Spectrum and the atomic absorption spectroscopic analysis confirmed that zinc ions penetrate into S. aureus cells, causing their death. The dead cells were easily removed, allowing ZOCZ to be reused. Image 105 • A multi-layer of S. aureus apparently formed on the surface of ZOCZ. • Effective removal of S. aureus is attributed to electrostatic interaction. • S. aureus cells in the outer layer are the result of settling. • Zinc ions accumulate in the S. aureus cells resulting in the death of cells. • Dead S. aureus cells close to the surface of ZOCZ allow easy reuse of ZOCZ. [ABSTRACT FROM AUTHOR]

A quinoline-based fluorescence sensor QDTD was developed for Zn2+. QDTD can detect Zn2+ by fluorescence turn-on. Detecting limit (0.27 μM) of QDTD for Zn2+ was far below WHO standard (76.0 μM). For the practical application, compound QDTD could be used to determine Zn2+ in real samples and applied to the test kit. More importantly, QDTD was expertly applied for Zn2+ imaging in HeLa cells and zebrafish with good membrane-permeability. Detection mechanism of Zn2+ ion by compound QDTD was suggested through the analytical tools like 1H NMR titration, ESI-MS, Job plot, fluorescent and UV–vis titration, and theoretical calculations, and through the synthesis and applications of a model compound AAQA. Unlabelled Image • A highly selective fluorescent chemosensor QDTD for Zn2+ was designed and synthesized. • QDTD could detect Zn2+ by fluorescence turn-on with the low detection limit (0.27 μM). • Sensor QDTD was applied to the real water samples and test strip. • Sensor QDTD could successfully quantify Zn2+ in HeLa cells and zebrafish. [ABSTRACT FROM AUTHOR]

Abstract A new quinoline-based fluorescent chemosensor MDCQA was designed and synthesized for the relay sensing of Zn2+ and S2−. MDCQA showed turn-on fluorescence toward Zn2+, and the resulting complex was able to detect S2− among the competitive anions by turn-off fluorescence. Detecting limits (0.06 μM and 2.33 μM) for zinc ion and sulfide were remarkably below WHO guidelines (76.0 μM for zinc ion and 14.7 μM for sulfide). In addition, sensor MDCQA successfully operated for imaging Zn2+ in live zebrafish larvae and quantifying it in real water samples. The detecting properties and mechanisms of MDCQA toward zinc ion and sulfide were demonstrated by UV–vis and fluorescence spectroscopy, NMR titration, DFT calculations and ESI-Mass. Graphical abstract Image 1 Highlights • A quinoline-based fluorescent sensor MDCQA was developed for the relay detection of Zn2+ and S2−. • MDCQA could detect Zn2+ by turn-on fluorescence and the resulting complex detected S2− by turn-off fluorescence. • MDCQA successfully detected Zn2+ in real water samples and in vivo. • Sensing mechanisms of MDCQA toward Zn2+ and S2− were demonstrated by the spectroscopic studies and DFT calculations. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel naphthyridyl derived Schiff-base 1 was designed and synthesized. • Significant fluorescence enhancement at 504 nm was observed with addition of Zn2+ to 1 solution. • High selectivity and sensitivity of 1 towards Zn2+ over other metal ions were obtained. • The mechanism for the responses of 1 to Zn2+ was investigated. Abstract In this study, bearing 4-methyl-7-acetamide-1,8-naphthyridyl group as the fluorophore and the receptor, we designed and synthesized a new-type Schiff-base ligand 1 which was identified as a Zn2+ fluorescent probe. The excellent selectivity and high sensitivity of this as-synthesized fluorescent probe 1 towards Zn2+ over other various biogenic metal ions were observed, for that only Zn2+ induced a drastic enhancement by about 63-fold in intensity of fluorescence emission at 504 nm, and the limit of detection (LOD) could reach 7.52 nM. Moreover, the formation of a 2:1 complex between this probe 1 and Zn2+ was determined, and the perfect invertibility and renewability of this probe 1 for sensing Zn2+ were also demonstrated. As a result, the practical applications of 1 were broadened for sensing and monitoring Zn2+ environmentally and biologically. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of a Eu(III)/Zn(II)-based heterometallo-supramolecular polymer (polyEuZn). • Eu(III) and Zn(II) ions introduced alternately in the polymer. • An ethylene glycol solution of polyEuZn with white-light-emission (Φ PL : 0.54, x = 0.31, y = 0.33). • Very strong white-light-emission based on the intramolecular energy transfer. Abstract By utilizing energy transfer from ligands to metal ions, efficient white-light-emission (Φ PL : 0.54, x = 0.31, y = 0.33) was realized in a heterometallo-supramolecular polymer with Eu(III) and Zn(II) ions introduced alternately. The polymer showed strong white-light-emission even in the film state as well as in solution. [ABSTRACT FROM AUTHOR]

Abstract A novel Schiff base chemosensor HMID, ((E)‑1‑((2‑hydroxy‑3‑methoxybenzylidene)amino)imidazolidine‑2,4‑dione), have been designed and synthesized. Sensor HMID showed a selectivity to Zn2+ through fluorescence enhancement in aqueous solution. Its detection limit was analyzed as 11.9 μM. Importantly, compound HMID could be applied to image Zn2+ in live cells. Detection mechanism of Zn2+ by HMID was suggested to be an effect of chelation-enhanced fluorescence (CHEF) by DFT calculations. Moreover, HMID could detect Cu2+ with a change of color from colorless to pink. The selective detection mechanism of Cu2+ by HMID was demonstrated to be the promotion of intramolecular charge transfer band by DFT calculations. Additionally, HMID could be employed as a naked-eye colorimetric kit for Cu2+. Therefore, HMID has the ability as a 'single sensor for dual targets'. Graphical Abstract Unlabelled Image Highlights • New Schiff-base chemosensor HMID was developed for detection of Zn2+ and Cu2+. • HMID can detect Zn2+ through "turn on" fluorescence in living cells. • HMID was used to detect Cu2+ from colorless to pink though ICT mechanism. • Chemosensor HMID could be used as a practical visible colorimetric test kit for Cu2+. • Sensing mechanisms for Zn2+ and Cu2+ by HMID were explained by DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract 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. Graphical Abstract Unlabelled Image Highlights • A coumarin based fluorescent probe was synthesized. • The probe was selectively detected zinc ion in aqueous CH 3 CN. • The sensor was applied for detection of zinc ion in a cell. [ABSTRACT FROM AUTHOR]

A fluorescent probe is constructed to quickly and accurately detect bisulfite. The detection mechanism was considered to operate via the bisulfite, causing deprotonation of amido bond of 8-aminoquinoline derivative leading to fluorescence enhancement. The probe has a good selectivity for bisulfite over the other competitive substances such as F − , Cl − , Br − , I − , C 2 O 4 2− , NO 2 − , ClO 4 − , OAc − , PO 4 3− , CO 3 2− , HCO 3 − , HS − , HSO 4 − , SCN − , SO 4 2− , S 2 O 3 2− , Cys, Hcy and GSH. There is a good linear relationship between fluorescence intensity and the concentration of bisulfite in the range of 0–200 μM. The limit of detection was calculated to be 0.61 μM. Furthermore, the probe has also been successfully used for imaging bisulfite in living cells. [ABSTRACT FROM AUTHOR]

A new multifunctional sensor ( L1 ) based on phenylene-acetylene was designed and synthesized. L1 showed an excellently colorimetric response toward Fe 2+ with a detection limit of 2.0☓10 −8 M. This result indicated that L1 can sensitive detect Fe 2+ by “naked eye” and discriminate iron types in different oxidative states. Simultaneously, L1 can ratiometric fluorescent detection of Cd 2+ and Zn 2+ with detection limits of 2.62☓10 -8 M and 2.03☓10 -9 M, respectively. L1 can distinguish Cd 2+ and Zn 2+ according to differently emissive colours, after addition of Cd 2+ and Zn 2+ to the blue emissive solution of L1 , cyan and yellow-green fluorescence emission were observed, respectively. The binding modes of L1 with Fe 2+ , Cd 2+ and Zn 2+ were evidenced by 1 H NMR, Job’s plot and ESI-MS. Water samples and On-site test paper experiments for detecting Fe 2+ , Cd 2+ and Zn 2+ were successfully implemented for practical application in environment. [ABSTRACT FROM AUTHOR]

A novel multifunctional probe, L , based on triphenylamine o -hydroxyl Schiff base was constructed for the sequential detection of Zn 2+ /P 2 O 7 4− . Interestingly, probe L also showed two-photon fluorescent “off-on” response to Zn 2+ along with a large effective two-photon absorption cross-section value of 240 GM at 720 nm, a low cytotoxic and a moderate photostability, which made L a good candidate for two-photon fluorescence microscopy imaging and monitoring the fluctuation of exogenous Zn 2+ . [ABSTRACT FROM AUTHOR]

A simple quinoline-based derivative (AQDPA) was developed as a highly efficient fluorescent sensor for sensing Zn 2+ and sequential recognition of pyrophosphate and sulfur ions. This chemosensor was synthesized from diisopropylamine and 2-chloro-N-(quinolin-8-yl)acetamide. The non-fluorescence sensor displayed significant and specific fluorescence enhancement after binding to Zn 2+ with high selectivity. The fluorescence titration analysis shows a detection limit for Zn 2+ at 4.1 × 10 −8  M. The sensing mechanisms of AQDPA binding to Zn 2+ were supported by 1 H NMR, HR-MS analysis, and density functional theory (DFT) study. Moreover, the fluorescence imaging in HeLa cells suggested that this simple sensor had great potential in the application of biological imaging. [ABSTRACT FROM AUTHOR]

Novel 4-amino-2-methyl-8-(trifluoromethyl)quinoline based magnetic nanosensors, Fe 3 O 4 @SiO 2 -PEG-4AQ and Fe 3 O 4 @SiO 2 -4AQ, were successfully fabricated and characterised. Enhanced fluorescent intensity was demonstrated by both nanosensors. Upon complexation with zinc ions, a further enhancement of 13.5-fold was revealed by Fe 3 O 4 @SiO 2 -PEG-4AQ. A red shift of 42 nm was also observed. The presence of other metal cations including Ni 2+ , Co 2+ , Ca 2+ , Cd 2+ , Hg 2+ , Mg 2+ , Mn 2+ and Ag + , showed no interference towards Zn 2+ . A sensitive detection limit of 0.0065 μM and 0.0125 μM was indicated by Fe 3 O 4 @SiO 2 -PEG-4AQ and Fe 3 O 4 @SiO 2 -4AQ respectively. The high sensitivity and selectivity remained constant within a wide range of pH values and were reversible upon treatment with EDTA. The PEG spacer between the magnetic core and the fluorophore offered further improvement of fluorescence intensity and detection sensitivity. To the best of our knowledge, this is the first study on 4-aminoquinoline based reusable nanochemosensor for zinc ion detection. [ABSTRACT FROM AUTHOR]

The fluorescence properties of four simple Schiff bases (LH 2 , LDMH 2 , LH 2 H and LDM H H 2 ) and their potential application as chemosensors for the detection of zinc ion in aqueous solution have been investigated. While LH 2 and LDMH 2 have displayed specific recognition to Zn(II), the reduced derivatives (LH 2 H and LDM H H 2 ) of these ligands have shown no fluorescence response due to the lack of C N group. The Job plots, fluorescence titration experiments and ESI-MS results indicate the formation of 1:1 complexes between sensors and Zn(II). The analytic methods based on LH 2 and LDMH 2 as chemosensors have been proposed and optimized to detect Zn(II) ions in aqueous solution. The optimized methods have shown a good range of linearity, high precision, good accuracy and low detection limit. As an alternative to these methods, LH 2 and LDMH 2 have the capability to detect Zn(II) ions by naked eye under UV lamp. Moreover, LH 2 -Zn and LDMH 2 -Zn complexes have the ability to be a staining agent for identifying the radiation treatment of food by DNA comet assay. [ABSTRACT FROM AUTHOR]

Two novel salen based chemosensors have been successfully synthesized. UV–vis absorption, fluorescence emission spectroscopy and cyclic voltammetry (CV) were exploited to investigate their recognition toward various metal ions, including Na + , K + , Mg 2+ , Al 3+ , Zn 2+ , Ag + , Pb 2+ , Co 2+ , Li + , Ba 2+ , Ca 2+ , Cd 2+ , La 3+ , Cu 2+ and Mn 2+ ions. The results indicated that the sensor L1 and L2 exhibited highly selective and sensitive recognition for Zn 2+ ions. The binding stoichiometry ratio of L1-Zn 2+ /L2-Zn 2+ were recognized as 4:1 by the method of Job's plot. Meanwhile, this investigation is confirmed by 1 H NMR. These results indicated that L1 and L2 can be applied as chemosensor for the detection of Zn 2+ ion. [ABSTRACT FROM AUTHOR]

Contrary to organic solvent-induced aggregation of Au nanoclusters (AuNCs), herein, we reported aggregation induced emission enhancement (AIEE) of AuNCs in an aqueous media through confinement of AuNCs by in situ formed Zn-MOF for detecting Zn 2+ . Glutathione capped AuNCs (GSH-AuNCs) was synthesized through reduction of Au 3+ by glutathione. Zn 2+ could significantly enhance the fluorescence of GSH-AuNCs upon addition of 2-methylimidazole, which was attributed to the formation of Zn-MOF. XRD and TEM were used to characterize the in situ formed Zn-MOF. Zn 2+ induced aggregation was demonstrated by dynamic light scattering and TEM. The quantum yields (QYs) of AuNCs after aggregation induced by in situ formed Zn-MOF attained to 36.6%, which was nearly 9 times that of the sole AuNCs. On this basis, a fluorogenic sensor was reported for Zn 2+ detection with a linear range from 12.3 nM to 24.6 μM and a detection limit of 6 nM (S/N = 3). The proposed sensor was successfully applied to assay the content of zinc in human serum, milk, water, and zinc sulfate syrup oral solution samples. The novel strategy proposed in this work may open a new window of interest in an unconventional application of gold nanoclusters/MOF nanoscale platform for metal ion detection and nutritional assessment of food. [ABSTRACT FROM AUTHOR]

We reported a new quinoline-based fluorescent probe 1 for Zn 2+ and S 2− . 1 showed a highly selective fluorescence enhancement toward Zn 2+ over other metal ions including Cd 2+ , and the resulting 1 -Zn 2+ complex could detect only S 2− among the various anions. The detection limits (0.09 μM and 0.88 μM) for Zn 2+ and S 2− were much lower than recommended values (76 μM for Zn 2+ and 14.8 μM for S 2− ) by WHO. Their recognition mechanisms were explained by Job plots, UV–vis titrations, 1 H NMR titrations, ESI-mass, and theoretical calculations. Moreover, compound 1 with the great photostability and low biotoxicity showed sequentially off-on-off fluorescent bio-imaging of Zn 2+ and S 2− in both HeLa cells and live zebrafish larvae. [ABSTRACT FROM AUTHOR]

A fluorescein based organic nanoparticles were prepared by using synthesized N -(3′,6′-dihydroxy-3-oxospiro[isoindoline-1,9′-xanthene]-2-yl)-2-hydroxybenzamide(FB). The interaction of series of metal ions with the FB nanoparticles (FBNPs) was investigated by means of fluorescence measurement. The selective and sensitive fluorescence enhancement was observed to FBNPs by the addition of Zn 2+ ion in an aqueous medium. The interaction of FBNPs and Zn 2+ introduced chelation enhanced fluorescence that was unaltered even addition of other metal ion. The formation of excited state complexation of FBNPs-Zn 2+ was supported by UV–vis absorption titration, fluorescence lifetime and zeta particle size of FBNPs with and without addition of Zn 2+ . The mode of binding and interaction was confirmed by results procured through NMR and IR spectroscopy. The stoichiometry and binding constant estimated by Job’s plot and Benesi-Hildebrand plot. The limit of detection (LOD) for Zn 2+ was 0.0011 μg/mL. The fascinating feature of present nano probe (FBNPs) is that outstanding intracellular Zn 2+ sensor in MDA-MB-231 living cells with nominal toxicity. The exceptional photo physical and biocompatible nature of FBNPs signifying on site application of prepared fluorescent organic nanoparticles in environmental as well as biomedical field. [ABSTRACT FROM AUTHOR]

A novel photochromic diarylethene derivative containing a 2-(methylthio)benzenamine Schiff base ( 1O ) unit was synthesized and its selective fluorometric/colorimetric sensing of multiple metal ions in methanol was demonstrated. The addition of Cu 2+ enhanced the absorption of 1O up to 44 folds with the concomitant color change from colorless to yellow, which could be easily observed by the naked eye. In addition, 1O exhibited selective fluorescence responses to Cu 2+ and Zn 2+ with different fluorescence signals. Cu 2+ quenched the fluorescence of 1O up to 98%, while Zn 2+ enhanced the fluorescence of 1O by 53.8 folds, accompanied by the fluorescence color changes from light red to dark and bright yellow, respectively. Both coordination stoichiometries between 1O and Cu 2+ , and 1O and Zn 2+ were determined to be 1:1. In all, diarylethene 1O can be potentially used as a chemosensor of both Cu 2+ and Zn 2+ . [ABSTRACT FROM AUTHOR]

Many diseases are connected with chemical substances, zinc ion is most important ion in chemical substances, because zinc ion (Zn 2+ ) has been shown extensively involved in various physiological and pathological processes. In this work, thymolphthalein with good biocompatibility was introduced, the probe was constructed with interweaved benzimidazole and phenol from into the fluorophore system, hydroxyl and amino creating a multipoint binding pocket, which zinc can coordinate in a cooperative breaking Excited-State Intramolecular Proton Transfer, ESIPT. The fluorescence of this probe adding Zn 2+ showed an obvious “turn on” in a quick response within 5 s. In addition, the probe had a good selectivity for zinc ion over other analytes. Furthermore, we also studied the fluorescence imaging of probe in the presence of Zn 2+ in living A549 cells. [ABSTRACT FROM AUTHOR]

A conjugated polymer probe comprised of fluorene, quinolone and benzothiazole units was designed and synthesized by the Suzuki coupling reaction. Through the studies of photophysical and thermal properties, the polymer displays blue-emitting feature and good thermal stability. A ratiometric fluorescence signal of the probe for Zn(II) was observed in ethanol with a new emission peak at 555 nm. The probe possesses a high selectivity and sensitivity for Zn(II) during familiar metal ions in ethanol. The detection limit of the probe for Zn (II) is up to 10 −8  mol/L. The electron distributions of the polymer before and after bonding with Zn (II) were investigated by the Gaussian 09 software, which agreed with the experimental results. Noticeably, based on the color property of the probe with Zn(II), a series of color test paper were developed for visual detecting Zn(II) ions. This work helps to provide a platform or pattern for the development of polymer fluorescence probe in the chemosensor field. [ABSTRACT FROM AUTHOR]

A new simple aminohydantoin-based fluorescent chemosensor 1 was designed for sequential detection of Zn 2+ and pyrophosphate in a near-perfect aqueous solution. 1 exhibited significant fluorescence intensity in the presence of Zn 2+ , and the resulting 1 -Zn 2+ complex showed subsequently the fluorescent quenching with pyrophosphate. The detection limit (0.32 μM) of 1 for Zn 2+ was far lower than the guideline of World Health Organization in drinking water. 1 was used to determine Zn 2+ concentration in various water samples. In addition, chemosensor 1 could be applied to sequentially detect Zn 2+ and pyrophosphate in living cells and zebrafish. The sensing mechanism of Zn 2+ by 1 was proposed to be an intramolecular charge transfer with theoretical calculations. [ABSTRACT FROM AUTHOR]

The absorption and fluorescence spectral study of the distyrylbenzene bearing two arms of the dipicolylaminomethyl groups, the effective ligands for Zn 2+ , was studied in the presence of Zn 2+ and ATP. Upon complexation of the distyrylbenzene with zinc ions in acetonitrile, enhancement of the fluorescence intensity was observed due to inhibition of intramolecular PET (photo-induced electron transfer) quenching, but no effect was found in aqueous media because the equilibrium laid to the free form of the ligands. In contrast, the addition of ATP disodium salt was effective to enhance the fluorescence intensity of the combination of the distyrylbenzne and Zn 2+ in aqueous media. This assembly was applied to the peroxyoxalate chemiluminescence system and a significant increase in the intensity was observed, which provides a potential detection for ATP by chemiluminescence. [ABSTRACT FROM AUTHOR]

Zinc ion detection in solution and living cells through colorimetric and ratiometric fluorescence with the novel Boron-dipyrromethene (BODIPY) based probe ( BNDP ) is described. The targeted modification of the established Bodipy fluorophore to trap zinc ions into the tetra-coordinating complex enables quantitative analysis of zinc ion concentrations detectable visually and through fluorescence due to the apparent color change between unbound and bound detection probe species. The equivalent-molar BNDP : Zn 2+ complexation, evident through the Job’s plot, 1 H NMR, and ESI–MS occurs with low nano-molar affinity, and induces significant changes in spectroscopic properties of BNDP , resulting in 27 nm and 40 nm red-shift in absorption and emission spectra, respectively. The complex is stable at physiological pH, allowing monitoring and quantifying levels of Zn 2+ concentration change in living cells, and detecting intracellular Zn 2+ released from intracellular metalloproteins. [ABSTRACT FROM AUTHOR]

Nanotechnology has become a ubiquitous part of our everyday life. Besides the already-known nanoparticles (NPs), plenty of new nanomaterials are being synthesized every day. Here, we explain the mechanism of the zinc oxide nanoparticles (ZnONPs) cytotoxicity in a cellular model of acute lymphoblastic leukaemia (CCRF-CEM). To do so, we investigated both possible hypotheses about the ZnONPs mechanism of toxicity: a free zinc ions release and/or reactive oxygen species (ROS) generation. Presented here results show that: A) EDTA protects the cells, whereas a common antioxidant agent (NAC) enhances the cytotoxic effect induced by ZnONPs, B) ZnONPs release zinc ions in vitro, C) ZnONPs upregulate the activity of antioxidative defence enzymes, which are Nrf2 transcription factor-dependent, D) The upregulation of ROS generation is correlated with the upregulation of reductive stress markers, E) ZnONPs treatment induces NADPH oxidases that cause excessive production of superoxide radicals in tested cellular model. Our results support the hypothesis that the mechanism of ZnONPs cytotoxicity is based on the release of free zinc ions. Nevertheless, both previously quoted hypotheses incompletely described the mechanism of action of ZnONPs. In this paper, we show that the mechanism of cytotoxicity of ZnONPs is based on the induction of reductive stress in CCRF-CEM cells, which is caused by free zinc ions released from ZnONPs. Therefore, the increase of oxidative stress markers is most likely a secondary response of the cells towards the Zn2+. These results provide a crucial expansion of the zinc ion hypothesis and thus explain the biphasic cellular response of CCRF-CEM cells treated with ZnONPs. [Display omitted] • Zinc Ion release is a primary toxicity mechanism of Zinc Oxide Nanoparticles • Zinc Oxide Nanoparticles lead towards reductive stress • Observed ROS generation is secondary response of cell to nanoparticles • Released zinc ions induce a generation of superoxide through NOX [ABSTRACT FROM AUTHOR]

For high-performance hybrid membranes, it is crucial to design multi-functional filler to rationally manipulate the structure-property relationship. In this study, a novel kind of hybrid membrane was fabricated by incorporating zinc ion loaded sulfonated pitch (SP-Zn 2+ ) nanofillers into poly (ether-block-amide) (Pebax) matrix for CO 2 /CH 4 separation. Sulfonated pitch (SP) with high sulfonate content was functionalized by zinc ion (Zn 2+ ) via complexation reaction to synthesize SP-Zn 2+ nanofillers with high Zn 2+ loading. Mixed gas separation performances of membranes with different SP-Zn 2+ loading were conducted. Meanwhile, the effect of operating pressure on separation performance and long-term operation stability were investigated. The hybrid membranes displayed significantly enhanced permeability and CO 2 /CH 4 selectivity. First, the hydrophilic sulfonate group in SP had good compatibility with Pebax matrix and effectively suppressed interfacial defects. Second, zinc ions and sulfonate group could form zinc-sulfonate complex network. The sulfonated moiety afforded strong affinity toward CO 2 due to multiple interactions whereas the Zn 2+ moiety afforded a transport highway for CO 2 . Third, the incorporation of SP-Zn 2+ nanofillers could disturb the Pebax chain packing and optimize the free volume characteristics. Particularly, Pebax/SP-Zn 2+ (2) membrane exhibited an increment of 104% and 70.2% in CO 2 permeability and CO 2 /CH 4 selectivity respectively, much higher than that of Pebax membrane. [ABSTRACT FROM AUTHOR]

To understand the effects of metal ions and nanoparticles (NPs) on nitrifying bacterial communities, this study investigates the impacts of zinc (Zn) NPs, zinc oxide (ZnO) NPs and Zn ions on the nitrifying bacterial communities. Under low Zn concentration (0.1 mg L −1 ), the nitrification rate was promoted by Zn ions and inhibited by the two NPs, indicating that the toxicity of NPs was caused by the NPs themselves instead of the released Zn ions. Further analysis showed that both Zn NPs and ZnO NPs could result in substantial reactive oxygen species (ROS) production in the nitrifying bacteria community. The inhibition was strongly correlated with amo A gene expression, but not with the expression of hao and nxr A genes. These results indicated that the main difference of the Zn ions and Zn NPs on nitrifying bacterial community could be due to the different impacts on the ROS production and amo A gene expression. Collectively, the findings in this study advanced understanding of the different effects of Zn NPs, ZnO NPs and Zn ions on nitrifying bacteria. [ABSTRACT FROM AUTHOR]

A novel oxo-spirocyclic structure bridged ditopic Schiff base fluorescent probe L has been successfully synthesized and characterized. Interestingly, probe L exhibits a specific turn-on response to zinc(II) ion in fluorescence with a high selectivity and sensitivity. Further study show that probe L could be applied in imaging of live cells for sensing zinc(II) ion. By contrast, those compounds ( L1 , L2 , and L3 ) with very similar structure to L lack this properties. The fluorescence intensity of L increases with Zn 2+ , which is less affected by other metal ions. The binding property of L with Zn 2+ was studied by a combination of technologies, such as Job's plot, 1 H NMR, ESI-MS, and DFT calculations. Moreover, we have successfully applied the probe L to detect Zn 2+ in cancer cell. We are anticipating that this new oxo-spirocyclic structure bridged ditopic Schiff base may provide a new idea for the design of fluorescent probe. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The construction of flexible platform possessing the functions of immobilizing, separating, rinsing, and high-throughput analysis plays a significant role in biological and clinical research. Herein, hollow-channel technique was integrated with lab-on-paper for the simultaneous determination of two different concentrations of Zn2+ based on the origami principle, in which microfluidic channels were first patterned on a cellulose paper using commercial solid-state wax printer. Hollow-channels were created by laser cutting method as the role of both injecting ending and reaction tank. After screen printing three electrodes system, the resulting planar paper sheets were then folded into steric structures and functionalized by in-situ synthesized reduced graphene oxide. As a proof-of-concept, such lab-on-paper device was employed in the ratiometric electrochemical monitoring of zinc ion from the environment and HepG2 cells extract, by combining with co-catalysis of porous metal-organic frameworks and hemin/G-quadruplex toward H 2 O 2 in the linear range of 0.1–7,000 nmol/L. The results indicated that integrating hollow-channel with steric lab-on-paper offered a new methodological approach for the development of metal ions monitoring research. It is believed that it could be useful for various point-of-care related research fields, such as, on-site environmental monitoring, food safety, and disease diagnosis. [ABSTRACT FROM AUTHOR]

In this work, we prepared glutathione (GSH)-capped copper nanoclusters (Cu NCs) with red emission by simply adjusting the pH of GSH/Cu 2+ mixture at room temperature. A photoluminescence light-up method for detecting Zn 2+ was then developed based on the aggregation induced emission enhancement of GSH-capped Cu NCs. Zn 2+ could trigger the aggregation of Cu NCs, inducing the enhancement of luminescence and the increase of absolute quantum yield from 1.3% to 6.2%. GSH-capped Cu NCs and the formed aggregates were characterized, and the possible mechanism was also discussed. The prepared GSH-capped Cu NCs exhibited a fast response towards Zn 2+ and a wider detection range from 4.68 to 2240 μM. The detection limit (1.17 μM) is much lower than that of the World Health Organization permitted in drinking water. Furthermore, taking advantages of the low cytotoxicity, large Stokes shift, red emission and light-up detection mode, we explored the use of the prepared GSH-capped Cu NCs in the imaging of Zn 2+ in living cells. The developed luminescence light-up nanoprobe may hold the potentials for Zn 2+ -related drinking water safety and biological applications. [ABSTRACT FROM AUTHOR]

A new simple quinoline-based chemosensor 1 was synthesized for Zn 2+ . 1 showed the selective fluorescence enhancement in the presence of Zn 2+ with a 1:1 stoichiometry in a near-perfect aqueous solution (bis-tris buffer:DMSO = 999:1), which was reversible with the addition of ethylenediaminetetraacetic acid (EDTA). The detection limit (0.6 μM) of 1 for Zn 2+ was much lower than World Health Organization guideline (76 μM) in drinking water. 1 was successfully applied to quantify and image Zn 2+ in water samples, test kit and living cells. The sensing mechanism of Zn 2+ by 1 via the intramolecular charge transfer was explained by theoretical calculations. [ABSTRACT FROM AUTHOR]

Two fluorescent sensors based on 1,10-phenanthroline, 2-(2-fluorophenyl)-1 H -imidazo[4,5- f ][1,10]phenanthroline (L1) and 2-(2-iodophenyl) -1 H -imidazo[4,5- f ][1,10]phenanthroline (L2) were designed and synthesized for sensitive and selective detection of Zn2+ in methanol, test paper and actual water samples. The results of strip test and real water sample test showed that sensors 1 and 2 have potential application in environmental metal ion recognition and detection. [Display omitted] • Two fluorescent sensors were designed and synthesized for sensitive and selective detection of Zn2+ in methanol, test paper and actual water samples. Synthesis of two fluorescent sensors based on 1,10-phenanthroline, 2-(2-fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L1) and 2-(2-iodophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L2). Their recognition of Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Cu2+, Mn2+, Eu3+, K+, Ca2+, Na+, Mg2+, Cr3+, Ag+, Hg2+, and Fe2+ was investigated using UV–vis absorption and fluorescence emission spectroscopy, and the results showed that L1 and L2 could be detected by significant fluorescence enhancement and naked eye color changes to achieve the identification of Zn2+. The high sensitivity of L1 and L2, with detection limits as low as 0.092 uM and 0.12 uM, respectively, indicates that the sensors have the ability to detect trace amounts of Zn2+. The binding stoichiometry ratio of L1-Zn2+ and L2-Zn2+ was determined by the Job's plot method to be 3:1. In addition, the test strip test and the actual water sample test showed their potential application in environmental ion identification. [ABSTRACT FROM AUTHOR]

A major way to reduce meat waste is to extend the shelf life of chilled meat with appropriate packaging. However, most of the packaging film cannot keep meat fresh because of its poor antibacterial and water resistance performance. In this paper, a composite film for chilled meat packaging was synthesized by simple self-assembly of zinc ions with chelating carboxyl groups. Introducing zinc ions into the composite system endows excellent water resistance and antibacterial properties to the film, which are demonstrated by the water vapor permeability and Escherichia coli and Staphylococcus aureus antibacterial tests. The as-prepared composite film also showed enhanced mechanical properties due to the formation of chelation bonds between zinc ions and carboxyl groups. Moreover, the chilled meat preservation test demonstrated the as-prepared composite film can significantly extend the shelf life of pork by five days, indicating its outstanding freshness preservation property. This work demonstrated a facile method to synthesize water-resistant and antimicrobial composite film, which can appear as an effective packaging material for chilled meat and offer a new idea to solve its short shelf-life problem. • Zinc ion self-assembly makes the composite film's water resistance and antibacterial performance significantly improved. • Carboxymethyl chitosan/zinc alginate composite film has a bactericidal rate of over 95 %. • Carboxymethyl chitosan/zinc alginate composite film significantly extends five days shelf life of cold meat. [ABSTRACT FROM AUTHOR]