Addition Of ZnCl2 Research Articles

Crystal water-capturing and film-forming bifunctional electrolyte additive for stabilizing sodium iron hexacyanoferrate cathode for Na-ion batteries

Due to its affordability, strong structural stability, and high rate capability, rhombohedral sodium ferrous hexacyanoferrate (FeHCF) has been identified as a potential cathode material for sodium ion batteries. Nevertheless, the presence of inherent crystal water and the susceptibility of its interface stability significantly hinder its capacity and cycling performance. In this study, we propose a novel modification approach involving the addition of ZnCl2 to effectively capture crystal water and facilitate the in-situ formation of a ZnO coating on the FeHCF surface. Due to the decreased crystal water content and the presence of stable ZnO interphases, the occurrence of side reactions between the electrode and electrolyte, as well as crystal particle cracks in FeHCF during repeated sodiation/desodiation processes, is effectively reduced. Consequently, the modified FeHCF demonstrates an extended operational lifespan of 1000 cycles, with an initial discharge capacity of 112.0 mAh/g and a capacity retention rate of 77.8 % at a current rate of 1C within the voltage range of 2.0–4.2 V. Our research offers valuable insights into the removal of crystal water and the engineering of incident interfaces to enhance the cycle life of FeHCF cathodes in sodium-ion batteries.

Preparation of porous carbon with high performance as lithium-ion battery anode utilizing FeCl3/ZnCl2 as modifying agents

The anode materials for lithium-ion batteries (LIBs) are prepared by one-step carbonization using urea-impregnated cotton stalk (CS) as a carbon precursor and ZnCl2 and FeCl3 as an activator and catalyst, respectively. The addition of ZnCl2 contributes to the development of mesopore. Incorporating FeCl3 improves the graphitization of porous carbon, but has no significant effect on layer spacing. In addition, FeCl3 catalysis can increase the specific surface area and pore volume of porous carbon, especially the development of pore structure below 10 nm. In terms of electrochemical performance, the porous carbon is prepared at CS: ZnCl2: FeCl3 = 1:1:1 and possessed the best performance, with a reversible capacity of 487.7 mAhg−1 after 100 charge–discharge cycles at 0.1 Ag−1 and specific capacity retention of 83.61 %. This study greatly improves the cycling stability of the battery while reducing the amount of mixed salt, which is extremely significant for subsequent research.

An insight into the role of the N-terminal domain of Salmonella CobB in oligomerization and Zn2+ mediated inhibition of the deacetylase activity.

Prokaryotic deacetylases are classified into nicotinamide adenine dinucleotide (NAD+)-dependent sirtuins and Zn2+-dependent deacetylases. NAD+ is a coenzyme for redox reactions, thus serving as an essential component for energy metabolism. The NAD+-dependent deacetylase domain is quite conserved and well characterized across bacterial species like CobB in Escherichia coli and Salmonella, Rv1151c in Mycobacterium, and SirtN in Bacillus subtilis. E. coli CobB is the only bacterial deacetylase with a known crystal structure (PDB ID: 1S5P), which has 91% sequence similarity with Salmonella CobB (SeCobB). Salmonella encodes two CobB isoforms, SeCobBS and SeCobBL, with a difference of 37 amino acids in its N-terminal domain (NTD). The hydrophobic nature of NTD leads to the stable oligomerization of SeCobBL. The homology modeling-based predicted structure of SeCobB showed the presence of a zinc-binding motif of unknown function. Tryptophan fluorescence quenching induced by ZnCl2 showed that Zn2+ has a weak interaction with SeCobBS but higher binding affinity toward SeCobBL, which clearly demonstrated the crucial role of NTD in Zn2+ binding. In the presence of Zn2+, both isoforms had significantly reduced thermal stability, and a greater effect was observed on SeCobBL. Dynamic light scattering (DLS) studies reflected a ninefold increase in the scattering intensity of SeCobBL upon ZnCl2 addition in contrast to an ∼onefold change in the case of SeCobBS, indicating that the Zn2+ interaction leads to the formation of large particles of SeCobBL. An in vitro lysine deacetylase assay showed that SeCobB deacetylated mammalian histones, which can be inhibited in the presence of 0.25-1.00mM ZnCl2. Taken together, our data conclusively showed that Zn2+ strongly binds to SeCobBL through the NTD that drastically alters its stability, oligomeric status, and enzymatic activity in vitro.

Structural, Optical and Magnetic Investigations on Pure and Copper Doped ZnO@ZnS Core Shell Nanoparticles for Biological Applications

ZnO nanoparticles were synthesized by co-precipitation with no capping agent followed by covering with ZnS using a solutionbased chemical method at low temperature. By varying the solution concentration, it was found that the fully-covering ZnS shell forms by a reaction of Na2 S with ZnO NPs followed by the formation of ZnS nano-crystals by the reaction of Na2S with ZnCl2 . The mechanism that led to full coverage of the ZnO core is proposed to be the addition of ZnCl2 at a later stage of the growth which guarantees a continuous supply of Zn ions to the core surface. Moreover, the ZnS nano- crystals that uniformly cover the ZnO NPs show no epitaxial relationship between the ZnO core and ZnS shell. The slow atomic mobility at the low reaction temperature is attributed to the non-epitaxial uniform ZnS shell growth. The rough surface of the ZnO grains provides initial nucleation positions for the growth of the ZnS shell nano-crystals. The low growth temperature also inhibits the abnormal growth of ZnS grains and results in the homogeneous coverage of ZnS nano-crystals on the ZnO core surface. The morphology and structure of samples are verified by X-ray diffraction (XRD). Identification of unknown substances and quantitative analysis can be done by FTIR. The absorption and reflectance of the nanoparticles were analyzed by UV Visible spectroscopy.

Matrix metalloproteinase- 9 may contribute to collagen structure modification during postmortem aging of beef

Matrix metalloproteinases (MMPs) are responsible for the turnover of intramuscular connective tissue in live animals. We hypothesize that MMPs may play a role in postmortem aging of beef muscles for the degradation of connective tissues. Four different experiments were performed to: 1) characterize MMP activity during postmortem aging of beef; 2) determine if the native beef MMP can contribute to connective tissue degradation in a simulated standard industry postmortem aging condition; 3) explore approaches to improve the native beef MMP activity and 4) characterize MMP activity in beef from cattle supplemented with supranutritional level of Zn. In experiment 1, MMP was active throughout the entire aging periods (3, 21, 42 and 63 d) for beef muscles Longissimus lumborum, Gluteus medius and Gastrocnemius, and the unknown MMP responsible for the collagen degradation was identified as MMP-9 by Western Blot. In experiment 2 and 3, MMP-9 activity was noticeable in the gels after 42 d of storage in the cooler. Moreover, the addition of ZnCl2 in the model system significantly increased MMP-9 activity when compared to the control (P < 0.01). In experiment 4, Longissimus thoracis from animals supplemented with a supranutritional Zn level had increased Zn availability and MMP-9 activity than those from animals fed with a control diet (P < 0.05). Further research is needed better understand MMP-9 mechanism during postmortem aging of meat. With a better understanding of MMP-9 in the aging process, the beef industry can provide better connective tissue management strategies for lower-quality beef cuts.

Influences of the Reaction Temperature and Catalysts on the Pyrolysis Product Distribution of Lignocellulosic Biomass (Aspen Wood and Rice Husk).

It is important to clarify the distribution of pyrolysis products from lignocellulosic biomass for its thermal transformation to produce high-quality bio-oil. Influences of the reaction temperature and catalysts on the pyrolysis product distribution from aspen wood (AW) and rice husk (RH) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The difference in components from the lignocellulosic biomass results in different pyrolysis characteristics of the biomass raw materials. The reaction temperature significantly influences the product distribution from AW and RH pyrolysis. In all AW catalysis experiments, acids (8.35%), ketones (3.79%), phenols (4.73%), and esters (1.50%) have the lowest content while carbohydrates (48.75%) demonstrate the highest content when taking zinc chloride (ZnCl2) as the catalyst; the HZSM-5 molecular sieve (HZSM-5) promotes the generation of esters (7.97%) and N-compounds (22.43%) while inhibiting production of aldehydes (2.41%); addition of an MCM-41 molecular sieve (MCM-41) is conducive to increasing the contents of aldehydes (21.29%), furans (5.88%), ketones (22.30%), acids (20.46%), and hydrocarbons (4.85%), while reducing the contents of alcohols (0) and carbohydrates (0). In all RH catalysis experiments, the addition of ZnCl2 helps increase the content of carbohydrates (39.16%) and decrease the contents of ketones (3.89%), phenols (5.20%), alcohols (2.34%), esters (1.13%), and N-compounds (3.09%); when applying HZSM-5 as the catalyst, hydrocarbons (18.28%) and alcohols (6.66%) reach their highest content while acids (13.21%) have the lowest content; MCM-41 promotes the generation of aldehydes (25.33%) and furans (5.55%) while inhibiting that of carbohydrates (1.42%).

Synthesis of Bis-tetraphenylethene as a Novel Turn-On Selective Zinc Sensor.

The main purpose of this study is the synthesis of novel fluorescent Bis-TPE and the investigation of its wide range of photochemical behaviors. For this purpose, initially, Bis-TPE was synthesized. Following this, the interactions of Bis-TPE with a wide range of ions were studied in EtOH using ultraviolet-visible (UV-vis) and fluorescence spectroscopy. As a result of all UV-vis and fluorescence studies, it was determined that Bis-TPE showed turn-on sensor features against Zn2+ ions. Moreover, the limit of detection (LOD) and Ka values of Bis-TPE/Zn2+ were calculated as 0.97 μM (970 nM) and 3.76 × 105 M-1, respectively. Moreover, all reversal studies resulted in switchable on/off variation of the alternative addition of ZnCl2 and [Bu4N]OH to Bis-TPE. This result also implies that the probe Bis-TPE also exhibits specific OH- sensor properties in the presence of zinc.

Synthesis of single‐crystalline InP tetrapod nanocrystals via addition of ZnCl2

AbstractRecently, single‐crystalline indium phosphide (InP) tetrapods, which allow an exciton to act in a true tetrapodal geometry, were successfully synthesized and proved as a useful platform to study multiple exciton behaviors. We used ZnCl2 precursor, a commonly used additive in the synthesis of aminophosphine‐based InP nanocrystals to enhance the optical performance, and successfully synthesized InP tetrapods (InP‐ZnCl2) with the narrower arm length distribution. Interestingly, no distinct enhancement in photoluminescence was observed while the arm length of the InP tetrapod was suppressed with the addition of ZnCl2. Further shell growth on InP‐ZnCl2 successfully preserved tetrapodal geometry in InP‐ZnCl2/ZnSe and showed higher photoluminescence than that of tetrapodal InP/ZnSe. The crystal structure of InP‐ZnCl2 was also retained even along with various Zn feed ratios as observed in x‐ray diffraction (XRD) patterns and showed no peak shift as Zn only passivates the surface of InP tetrapods. These results provide a platform to study the role of Zn precursor.

Effects of zinc chloride on boar sperm quality during liquid storage at 17°C.

The aim of this study was to evaluate the effects of zinc chloride (ZnCl2 ) at 20, 50, 100, and 200μg/mL on the quality of seminal plasma-free boar sperm stored at 17°C for 7 days and to explore the underlying mechanisms. Boar sperm were collected and incubated in non-capacitation/capacitation medium to analyze sperm quality. In the non-capacitated state, the addition of ZnCl2 at 20 and 50μg/mL improved the survival rate and plasma membrane integrity of boar sperm (p < 0.05). Compared to the control group, the addition of ZnCl2 significantly increased total antioxidative capacity and CuZn superoxide dismutase activity, while reducing the malondialdehyde content (p < 0.05). ZnCl2 at 100 and 200μg/mL significantly decreased sperm motility, protein kinase A (PKA) substrate phosphorylation, and tyrosine phosphorylation. These proteins were mainly located on the mid-pieces of the flagellum. The addition of ZnCl2 at 20 and 50μg/mL conveyed a protective effect to boar sperm stored at 17°C. Furthermore, ZnCl2 at 100 and 200μg/mL inhibited sperm motility via tyrosine phosphorylation, thus preventing the 'capacitation-like' state. In the capacitated state, there was no change in PKA substrate phosphorylation and tyrosine phosphorylation of the mid-pieces of the flagellum compared to the control groups, indicating that the addition of Zn2+ did not negatively affect capacitation of preserved sperm. ZnCl2 showed protective capacity to the preservation extender used for boar sperm during the process of 17°C storage, and the optimal concentration of ZnCl2 for the preservation extender was 100μg/mL.

One-pot liquefaction of cellulose to ethyl levulinate via 1-sulfonic acid-3-methyl imidazolium trichlorozincate as Brønsted-Lewis catalyst

The direct conversions of cellulose to ethyl levulinate (EL) via Brønsted acidic ionic liquid (BAIL), Lewis acidic ionic liquid (LAIL), and Brønsted-Lewis acidic ionic liquid (BLAIL) conducted in this study is a sustainable approach. Initially, BAIL 1-sulfonic acid-3-methyl imidazolium chloride [SMIM][Cl] was prepared by the mixing of 1-methylimidazole, dry dichloromethane, and chlorosulfonic acid. Then, Lewis acidic site was provided to the BAIL by the addition of zinc chloride (ZnCl2), to synthetize BLAIL 1-sulfonic acid-3-methyl imidazolium trichlorozincate, [SMIM][ZnCl3]. Meanwhile, LAIL 1-butyl-3-methyl imidazolium trichlorozincate [BMIM][ZnCl3] was prepared by the addition of ZnCl2 to a neutral 1-butyl-3-methyl imidazolium chloride [BMIM][Cl]. These three catalysts were then characterized and employed in the one-pot liquefaction process that was conducted in a stainless-steel batch reactor at 180 ˚C for 10 hr, by charging 0.6 g of cellulose, 40 mL of ethanol and 3 g of catalyst. A parameter study, mainly temperature (120–200) °C, time (2–10) hr, and cellulose loading (0.2–1.0) g, were then conducted to determine the selected parameters to obtain high EL yield. Among the employed ionic liquids (ILs), BLAIL [SMIM][ZnCl3] exhibited the highest catalytic activity, which was contributed mainly by its co-existence of Brønsted and Lewis acidic sites as detected in Fourier-Transform Infrared (FTIR) analysis, and its high acidic value. The maximum EL yield (20.27 wt%) was obtained under conditions of 180 °C, 6 hr, 0.6 of cellulose, and 3 g of [SMIM][ZnCl3]. The outcome of this study provides an insight on the potential of novel [SMIM][ZnCl3] in facilitating the direct cellulose ethanolysis to EL.

Plant-derived adhesive hydrogel with high stretchability and conductivity for wearable electronics

Nowadays, hydrogel-based sensors have drawn great attention owing to the growing demand for wearable devices. However, tailoring the property of the hydrogel sensor through a facile approach remains a great challenge. In this work, inspired by natural plants, a stretchable, adhesive and conductive hydrogel was prepared via the coordination between gallic acid (GA) and Zn2+ and chemical cross-linking. The dynamic crosslinking provided greater structural integrity for the polyvinyl alcohol / polyacrylamide (PVA/PAM) double network, endowing the hydrogel with high mechanical performance (0.25 MPa at 910% tensile strain, and 1.21 MPa at 70% compressive strain). Meanwhile, the presence of GA enabled the hydrogel with excellent repeatable adhesive performance, which greatly solved the problem of signal loss caused by poor adhesion. Moreover, the addition of ZnCl2 enhanced the ionic conductivity and gauge factor of the hydrogel. Besides, the conductive hydrogel exhibited successively stable changes of resistance signals under different external stimuli (5–500% strains and 80–200 mm/min rates) and superior durability (over 500 cycles). The hydrogel-based wearable sensors demonstrated excellent sensing performance in detecting various human motions. The multifunctional PVA/PAM/GA-Zn2+ hydrogel has significant applications in soft robots and healthcare monitoring as the flexible strain sensor.

ZnCl2-Enhanced Intrinsic Luminescence of Tin Chlorophosphate Glasses

This communication reports the intrinsic luminescence of tin chlorophosphate glasses. The glass maintains the low melting point characteristics of tin fluorophosphate glasses, and exhibits a red-shifted and broadened excitation wavelength peak. Tin chlorophosphate glasses can exhibit a broadband luminescence of 400–700 nm under an excitation of 380–430 nm. Furthermore, the introduction of ZnCl2 into tin chlorophosphate glasses can considerably enhance the luminescence without affecting their low-melting characteristics. The luminescence intensity can be increased fourfold, with the enhancement attributed to the reduced visible absorption, improved dispersion of Sn2+ ions, and the energy exchange between Sn2+ and Zn2+ in the glasses owing to the addition of ZnCl2.

Effect of crystal-shaped additives of precipitated calcium carbonate on the whiteness of modified fly ash and hand sheets

Fly ash was modified using calcium oxide and carbon dioxide. The morphology of precipitated calcium carbonate was controlled by adding different crystal-shape-forming additives. Effects of sodium hexametaphosphate, zinc chloride, sodium tetraborate decahydrate, and aluminium chloride on the crystal shape of precipitated calcium carbonate were studied. The effects of crystal-shaped additives of precipitated calcium on the whiteness of modified fly ash and hand sheets were analyzed. The results showed that the addition of ZnCl2 (0.35%) can play a role in coating fly ash well. The coating effect of the acicular, chain, and lamellar precipitated calcium carbonate on the surface of fly ash was slightly less effective than that of globular crystals.

Nitrogen-doped cotton stalk porous carbon composite as anode material for Lithium-ion battery

• The synergistic mechanism of ZnCl 2 and urea was systematically studied for LIB anode. • Porous carbon with high heteroatomic content(N-AC) has good electrochemical performance. • Development of pore structure is the basis for excellent electrochemical performance. • The increase of heteroatom content and layer spacing is the reason for the performance enhance. In this study, the raw material of cotton stalks, N source of urea, and activator of ZnCl 2 were used to prepare high N-doped cotton stalk activated carbon (N-AC) and exploring the synergistic mechanism of activator and dopant on electrochemical performance improvement. Addition of ZnCl 2 promoted the formation of mesopores, but urea inhibited the development of pore structures. In addition, the development of pore structure was the basis for excellent electrochemical performance. The co-modification promotes the retention of heteroatoms and the expansion of interlayer spacing on the basis of retaining the three-dimensional pore structure, which is also the main reason to obtain the higher electrochemical performance. N-AC, an LIB anode material, still maintained a specific capacity of 504.1 mAhg −1 after 100 cycles at current density of 0.1 Ag −1 . Under the high current density of 2 Ag −1 , N-AC showed a specific capacity of 250.32 mAhg −1 , which had good cycle performance and rate performance. This study discussed the mechanism of two modification methods to improve electrochemical performance, which provided a theoretical basis for future research.

Preparation of Porous Coke by Microwave Pyrolysis of Oily Sludge: Optimization Through Response Surface Methodology and TG-FTIR Analysis

Oily sludge (OS) is a kind of solid waste with precious oil resources in the petroleum industry. Because OS poses a severe threat to the environment, the treatment of OS has been widely studied. In this work, OS was used to prepare porous sludge coke a through microwave pyrolysis and one-step ZnCl2 activation technique. The response surface methodology was designed to optimize the parameters of the preparation process of porous sludge coke, and the interaction between the parameters was further analyzed. The experimental result showed that the model could fit the experimental results well. The optimal iodine adsorption value of porous sludge coke, 785.23 mg/g, was obtained by using the response surface methodology when the microwave power was 797 W, the ZnCl2 addition ratio was 0.5, and the pyrolysis time was 25 min. The experimental result showed that the model could fit the experimental results well. The influence of ZnCl2 on the pyrolysis of OS was investigated through TG-FTIR. The results showed that the presence of ZnCl2 could prevent the fracture of C-H bond, reduce the rate of carbon source loss caused by the fracture of long-chain hydrocarbons to produce short-chain hydrocarbons in OS, and enrich the carbon source of sludge coke. On the other hand, the molten ZnCl2 occupied the tiny pores when the oil components in the OS volatilized, which can enrich the pore volume of the sludge coke.

Lactoferrin with Zn-ion protects and recovers fibroblast from H2O2-induced oxidative damage

Lactoferrin (LF) has attracted great attention due to its various bioactivities, which depend on the degree of saturation with different cations. This study focused on the synergistic effect of LF and Zn2+ on human gingival fibroblasts (hGFs), considering antioxidant activities, cell proliferation, and collagen gene expression levels in these cells to improve the wound healing. The hGFs were cultured in an experimental medium, containing 1000 μg/mL of LF and various concentrations of ZnCl2. The cells were subjected to oxidative damage by exposure to 600 μM H2O2 for 30 min before incubation in the experimental medium. The cell proliferation rate and the relative gene expression levels of genes associated with apoptosis, antioxidant enzymes, and collagen were compared. H2O2 decomposition by LF was also measured using a colorimetric assay. LF enhanced hGF proliferation and the expression of collagen. Furthermore, LF directly scavenged H2O2 and prevented lipid peroxidation by enhancing the expression of glutathione peroxidase 4 gene expression, resulting in the prevention of apoptosis and recovery of the cells from H2O2-induced oxidative damage. The addition of ZnCl2 enhanced these results. The results indicated that LF with Zn-ion could play an important role in modulating the functions related to wound healing.

Removal of elemental mercury using magnetic Fe-containing carbon prepared from sludge flocculated with ferrous sulfate by zinc chloride activation

In this work, sewage sludge flocculated with ferrous sulfate (SFS) was treated by one-step pyrolysis and ZnCl2 activation to obtain magnetic Fe-containing carbon, which was used to remove elemental mercury (Hg0) from flue gas. When 30% ZnCl2 was added to SFS (names as SFS-30), sulfides, chloride, magnetic FexOy, as well as a suitable BET surface area were produced during pyrolysis. SFS-30 showed a maximum mercury removal efficiency of 96.1%. The presence of O2 and a low SO2 concentration enhanced Hg0 removal, while H2O vapor and a high concentration of SO2 inhibited it. The addition of ZnCl2 increased the BET surface area as well as the conversion of sulfate to sulfide, which were both beneficial for Hg0 removal. In addition, the generated magnetism during the pyrolysis process assisted in the recovery and utilization of SFS-30 in flue gas. After being magnetically separated from a mixture with fly ash, spent SFS-30 was thermally regenerated and recycled. After 8 Hg0 capture and regeneration cycles, the removal efficiency was not notably degraded, demonstrating that SFS-30 prepared by one-step pyrolysis with ZnCl2 activation can be used for Hg0 removal. The results of this study have guiding significance for practical engineering applications of this material.

The Effect of Ball-Milling on the Oxygen Reduction Reaction Activity of Iron and Nitrogen Co-Doped Carbide-Derived Carbon Catalysts in Acid Media

Storing renewable energy to complete the energy cycle is a crucial challenge in the movement from a fossil fuel-based economy to a circular one. In the hydrogen cycle, stored hydrogen is converted back to usable energy in a fuel cell. The biggest issue in proton exchange membrane fuel cells (PEMFC) is the replacement of noble metal catalysts with a non-precious metal catalysts (NPMC). Iron and nitrogen doped nanocarbon materials are among the most promising alternatives.In our previous works on iron and nitrogen doped carbide-derived carbons (CDC) we discovered that ball-milling of CDCs has a crucial effect on their porosity and the final activity of the catalyst.1,2 In this work,3 we study the effect of ball-milling conditions and compositions of catalyst precursors comprising a silicon carbide-derived carbon (SiCDC) on the properties of the final catalysts, most importantly their activity toward the oxygen reduction reaction (ORR). Ball-milling rates from 100 to 800 rpm were investigated with 400 rpm proving to be the optimum value. The effect of 1,10-phenanthroline-to-iron ratio in the precursor mixture was also studied, with a 12-1 molar ratio leading to the highest activity. Finally, ZnCl2 addition to the precursor mixture was explored as a pore former during pyrolysis. A ZnCl2-to-CDC mass ratio of 1 resulted in the highest ORR activity. 57Fe Mössbauer spectroscopy confirmed that most of the iron was atomically dispersed as Fe-Nx moieties (Figure 1, left). The most active catalyst showed a kinetic current density of 4.6 mA cm-2 at 0.8 V in rotating disk electrode tests and a current density of 18.6 mA cm-2 at 0.8 V in a single-cell proton exchange membrane fuel cell (Figure 1, right). References Ratso, N.R. Sahraie, M.T Sougrati, M. Käärik, M. Kook, R. Saar, P. Paiste, Q. Jia, J. Leis, S. Mukerjee, F. Jaouen, and K. Tammeveski, J. Mater. Chem. A, 6, 14663–14674 (2018).Ratso, M. Käärik, M. Kook, P. Paiste, J. Aruväli, S. Vlassov, V. Kisand, J. Leis, A. M. Kannan, and K. Tammeveski, Int. J. Hydrogen Energy, 44, 12636–12648 (2019).Ratso, M. T. Sougrati, M. Käärik, M. Merisalu, M. Rähn, V. Kisand, A. Kikas, P. Paiste, J. Leis, V. Sammelselg, F. Jaouen, and K. Tammeveski, ACS Appl. Energy Mater., 2, 7952–7962 (2019). Figure 1

Immobilization of thermolysin enzyme on dendronized silica supports. Evaluation of its feasibility on multiple protein hydrolysis cycles

This work evaluates different dendrimer-silica supports for the immobilization of enzymes by multipoint covalent binding. Thermolysin was immobilized on two dendrimers (PAMAM and carbosilane) with two different generations (zero (G0) and first (G1)). Results were compared with a control, a silica support functionalized with a monofunctional molecule. Dendrimers increased the number of available sites to bind the enzyme. Despite the enzyme was immobilized on all supports, G0 dendrimers immobilized a 30% more enzyme than G1. Thermolysin immobilized on G0 dendrimer supports showed the highest activity and could be employed in three consecutive hydrolysis cycles. Optimal immobilization time was 1 h while optimal protein loading was 25 mg enzyme/100 mg support. Enzyme activity was promoted when using 5 mg of immobilized enzyme at 750 rpm, 60 °C, and 2 h of hydrolysis. Under these conditions, the activity of thermolysin increased up to the 78% of the free enzyme activity. Kinetics of the hydrolysis reaction using the immobilized thermolysin was also studied and compared with the obtained using the free thermolysin. The addition of ZnCl2 and NaCl during the immobilization procedure increased thermolysin activity in the second (22% more) and in the third (14% more) hydrolysis clycles.

Deep-Red-Fluorescent Zinc Probe with a Membrane-Targeting Cholesterol Unit.

Organelle-targeting fluorescence probes are valuable because they can provide spatiotemporal information about the trafficking of analytes of interest. The spatiotemporal resolution can be improved by using low-energy emission signals because they are barely contaminated by autofluorescence noises. In this study, we designed and synthesized a deep-red-fluorescent zinc probe (JJ) with a membrane-targeting cholesterol unit. This zinc probe consists of a boron-azadipyrromethene (aza-BODIPY) fluorophore and a zinc receptor that is tethered to a tri(ethylene glycol)-cholesterol chain. In aqueous solutions buffered to pH 7.4, JJ exhibits weak fluorescence with a peak wavelength of 663 nm upon excitation at 622 nm. The addition of ZnCl2 elicits an approximately 5-fold enhancement of the fluorescence emission with a fluorescence dynamic range of 141000. Our electrochemical and picosecond transient photoluminescence investigations indicate that the fluorescence turn-on response is due to the zinc-induced abrogation of the formation of a nonemissive intramolecularly charge-separated species, which occurs with a driving force of 0.98 eV. The fluorescence zinc response was found to be fully reversible and to be unaffected by pH changes or the presence of biological metal ions. These properties are due to tight zinc binding with a dissociation constant of 4 pM. JJ was found to be nontoxic to HeLa cells up to submicromolar concentrations, which enables cellular imaging. Colocalization experiments were performed with organelle-specific stains and revealed that JJ is rapidly internalized into intracellular organelles, including lysosomes and endoplasmic reticula. Unexpectedly, probe internalization was found to permeabilize the cell membrane, which facilitates the influx of exogens such as zinc ions. Such permeabilization does not arise for a control probe without the tri(ethylene glycol)-cholesterol chain (JJC). Our results show that the membrane-targeting cholesterol unit can disrupt membrane integrity.