Aqueous Environment Research Articles

Aqueous co-solvent synthesis of Zeolitic Imidazolate Frameworks: The impact of co-solvents in the crystal growth kinetics

Zeolitic Imidazolate Frameworks (ZIFs) have been widely studied in recent decades in a variety of applications. However, a fundamental understanding of crystal growth kinetics as well as their formation mechanisms has been very limited. Underpinning such mechanisms might be of key importance for the predictable synthesis of ZIFs to rationally tune the structural and morphological properties for respective applications. Herein, the crystal growth kinetics and structural evolution of ZIF-8 crystals in various aqueous co-solvent reaction environments were studied with respect to synthesis time. By tracking the nucleation, crystal growth, stabilization and ripening, three potential kinetic formation mechanisms were proposed. More specifically, with methanol, isopropanol and acetone, a fast nucleation rate and crystal growth occurred within 60 minutes (min) at room temperature. However, ethanol and n-propanol showed prolonged nucleation which resulted in the slow formation of ZIF-L/ZIF-8 mixed phases at the early stage. Phase transformation to pure ZIF-8 was observed in longer syntheses. Nitrogen-containing solvent, N, N–dimethyl formaldehyde (DMF), was found to induce both nucleation and growth, resulting in large crystals in less than 60 min of fabrication. In each case, the crystal formation follows Avrami's classical model. Hence, by understanding the effects of co-solvents in ZIF nucleation, crystallization and phase selection, one can rationally design the crystals with predictable crystallinity, size, morphology, purity and surface properties for targeted applications such as adsorption of small molecules from aqueous mixtures.

Spatiotemporal Nitric Oxide Modulation via Electrochemical Platform to Profile Tumor Cell Response.

Nitric oxide (NO) is a gaseous molecule intricately implicated in oncologic processes, encompassing the modulation of angiogenesis and instigating apoptosis. Investigation of the antitumor effects of NO is currently underway, necessitating a detailed understanding of its cellular-level reactions. Regulating the behavior of radical NO species has been a significant challenge, primarily due to its instability in aqueous environments by rapid O2-induced degradation. In this study, we devised an electrochemical platform to investigate the cellular responses to reactive gaseous molecules. Our designed platform precisely controlled the NO flux and diffusion rates of NO to tumor cells. COMSOL Multiphysics calculations based on diffusion and reaction kinetics were conducted to simulate the behavior of electrochemically generated NO. We discerned that the effective distance, NO flux, and electrolysis duration are pivotal factors governing cellular response by NO.

Photo-reductive decomposition of perfluorooctane sulfonate (PFOS) and its common alternatives by UV/VUV/sulfite process: Mechanism, kinetic modeling, and water matrix effects

The present study investigated the photo-reduction of perfluorooctane sulfonate (PFOS) and its alternatives, focusing on decomposition mechanisms, active species involvement, the influence of background water constituents, and kinetic model development. The decomposition and defluorination rates followed the order of PFOS > PFHxS > 6:2 FTSA > PFBS, with shorter chains and CH2 linkers enhancing the resistance of PFOS alternatives against the attack of hydrated electrons (eaq−). Two primary pathways were identified during the photodegradation of PFAS: (i) H/F exchange at CF bonds with the lowest bond dissociation energies (BDEs) and (ii) functional group cleavage followed by short-chain PFCAs formation, with OH playing a crucial role in transforming intermediates. Adding iodide and elevated temperatures demonstrated a synergistic effect on PFBS decomposition and defluorination, with high temperatures promoting functional group cleavage as the preferred defluorination pathway. The study examined the impact of background water constituents in different aqueous environments, from surface waters to wastewater streams and ion-exchange brine concentrates. Chloride exhibited a concentration-based dual impact on the UV/VUV/sulfite process: promotive effects at low dosages (1–10 mM) by acting as a secondary eaq− mediator, and adverse effects at high dosages (20–500 mM) due to the scavenging effect of generated chlorine radicals (Cl). High ionic strength adversely affected eaq− quantum efficiency. Additionally, bicarbonate and natural organic matter (NOM) had opposing effects on PFOS photo-reduction, primarily through eaq− scavenging and pH alteration. Kinetic modeling revealed reaction rate constants of the studied PFAS with eaq− ranging from 1.8 × 106 to 1.3 × 109 M−1 s−1, corroborating the concentration profiles of active species and highlighting the reductive nature of sulfite-mediated processes.

Spatiotemporal Nitric Oxide Modulation via Electrochemical Platform to Profile Tumor Cell Response

Nitric oxide (NO) is a gaseous molecule intricately implicated in oncologic processes, encompassing the modulation of angiogenesis and instigating apoptosis. Investigation of the antitumor effects of NO is currently underway, necessitating a detailed understanding of its cellular‐level reactions. Regulating the behavior of radical NO species has been a significant challenge, primarily due to its instability in aqueous environments by rapid O2‐induced degradation. In this study, we devised an electrochemical platform to investigate the cellular responses to reactive gaseous molecules. Our designed platform precisely controlled the NO flux and diffusion rates of NO to tumor cells. COMSOL Multiphysics calculations based on diffusion and reaction kinetics were conducted to simulate the behavior of electrochemically generated NO. We discerned that the effective distance, NO flux, and electrolysis duration are pivotal factors governing cellular response by NO.

Preparation of ZIF‐8‐Based Functionalized Magnetic Nanocomposites and Their Application in Aqueous Environment

ABSTRACTIn this study, a functionalized magnetic powder complex porous carbon derived from ZIF‐8 (ZIF‐8@Na‐Cit@Fe3O4NPs@AC(500°C)) was prepared and applied for the waste liquid containing MB, TC, and Cu2+ adsorption removal. The ZIF‐8@Na‐Cit@Fe3O4NPs@AC(500°C) perfectly inherited the feature of parent ZIF‐8, posed a high specific surface area (SBET = 812.73 m2 g−1), be rich in surface nitrogen functional groups, and resulting in a good dynamic adsorption of the MB, TC, and Cu2+. The ZIF‐8@Na‐Cit@Fe3O4NPs@AC(500°C) exhibited the best adsorption performance of high‐concentration waste liquid containing MB, TC, and Cu2+, with equilibrium adsorption capacity of MB (408 mg g−1), TC (417 mg g−1), and Cu2+ (386 mg g−1), respectively. The acetone and toluene adsorption were spontaneously and exothermic, given the negative values of free energy (ΔG) and enthalpy (ΔH). The difference of MB, TC, and Cu2+ adsorption on ZIF‐8@Na‐Cit@Fe3O4NPs@AC(500°C) attributed to the affinity difference (polarity and molecular diameter) and the nitrogen‐containing functional groups (π‐π interaction and electrostatic attraction). Therefore, it was found that ZIF‐8@Na‐Cit@Fe3O4NPs@AC(500°C) could effectively adsorb MB, TC, and Cu2+, and ZIF‐8@Na‐Cit@Fe3O4NPs@AC(500°C) could remove more than 70% of the above pollutants after repeated use for four times; it has a good application prospect.

Surface ion-exchange induced Bi-rich Bi12O17Cl2/BiOCOOH/Bi2MoO6 heterojunction with oxygen vacancies for enhanced photocatalytic nitrogen fixation

Photocatalytic nitrogen reduction presents a promising technology for environmentally friendly ammonia synthesis under mild conditions. However, the performance of photocatalysts is often hindered by high charge carrier recombination and insufficient adsorption and activation of nitrogen molecules. A novel Bi12O17Cl2/BiOCOOH/Bi2MoO6 heterojunction photocatalyst was successful synthesis through surface ion-exchange technique by potassium chloride. The introduction of Bi-rich Bi12O17Cl2 on BiOCOOH/Bi2MoO6 heterojunction not only improves electron transfer efficiency due to the dual type-II heterojunction effect but also facilitates on-site N2 adsorption and activation for solar ammonia production by promoting oxygen vacancies. The high photocatalytic nitrogen fixation activity of the Bi12O17Cl2/BiOCOOH/Bi2MoO6 was 107.78 μmol g−1 h−1 without any sacrificial agent. DFT calculations indicate that oxygen vacancies serve as the active site for adsorbed N2, the hydrogenation process preferentially forms on the distal N2 atom with a lower activation energy about 0.6 eV. Therefore, the combination of oxygen vacancies and band engineering accelerates the production of ammonia. This endeavor holds the potential to unleash the capabilities of engineering for Bi-rich heterojunctions materials with oxygen vacancies, thereby achieving high-efficiency solar-driven N2-to-NH3 conversion in aqueous environments.

Determination of Taurine in Infant Formula and Adult/Pediatric Nutritionals by Ultra High-Performance Liquid Chromatography with Multiple Reaction Monitoring-Mass Spectrometry: Single-Laboratory Validation, First Action 2022.08.

Taurine (2-aminoethanesulfonic acid) is an essential β-amino acid, which is one of the most abundant intracellular amino acid component in humans. The level of free taurine in human milk is higher than in bovine milk. Since taurine is considered important for the development of a newborn, fortification of infant nutrition with taurine is common. This publication describes a rapid method for the determination of taurine in infant formula and adult/pediatric nutritionals. This publication demonstrates the suitability and applicability of the method to determine taurine content in infant formula and adult/pediatric nutritionals. Test portions are deproteinized by acid in an aqueous environment prior to analysis. The level of taurine is analyzed by hydrophilic interaction chromatography (HILIC) coupled with multiple reaction monitoring MS (MRM-MS). Quantitation is accomplished using a stable isotope-labeled internal standard (SILS) for taurine. The accuracy of the method was validated using standard reference materials and spike recovery studies. The average recoveries ranged between 92% and 105%. The relative standard deviation repeatability (RSDr) and relative standard deviation intermediate precision (RSDiR) were in the range of 0.7-4.6% (RSDr) and 1.3-6.7% (RSDiR). The limit of quantitation (LOQ) was below the requirement of 0.5 mg/100 g. The single-laboratory validation (SLV) of the method for determination of taurine content in infant formula and adult/pediatric nutritionals demonstrates that it meets the requirements per AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR) 2014.013. A fast method to selectively determine the content of taurine in infant formula and adult/pediatric nutritionals was evaluated and found to be fit for purpose for routine product compliance testing. Based on the results of this SLV, the method was approved by the AOAC Stakeholder Program on Infant Formula and Adult Nutritionals (SPIFAN) Expert Review Panel for SPIFAN Nutrient Methods for First Action Official MethodsSM status.

Bismuthenium Cations for the Transport of Chloride Anions via Pnictogen Bonding.

Our interest in the design of heavy pnictogen-based Lewis acids for anion trafficking across biological membrane mimics has led us to investigate trivalent bismuthenium cations as chloride anion transporters. Here, we describe two chlorodiarylbismuthines, elaborated on a peri-substituted acenaphthene backbone and stabilized by an adjacent thio- or seleno-ether functionality that engages the bismuth center in a Ch→Bi interaction (Ch = chalcogen). These new derivatives are stable in aqueous environment and readiliy transport chloride anions across the membrane of phospholipid-based vesicles loaded with KCl. In addition to establishing the use of such motifs in anion transport, this investigation shows that the Lewis acidity, lipophilicity, and thus chloride transport properties depend on the nature of the chalcogen.

Concurrent elimination of arsenic and nitrate from aqueous environments through a novel nanocomposite: Fe3O4-ZIF8@eggshell membrane matrix

The high concentration of nitrate and arsenic as potentially toxic elements (PTEs) with carcinogenic properties in many groundwater sources worldwide is a concern for health and the environment. This work checked the capacity of a novel nanocomposite, Fe3O4-ZIF8@eggshell membrane matrix (F-ZIF8@EMM) for concurrently eliminating arsenic and nitrate, two of the most encountered hazardous pollutants in drinking water. Contact time (30–120 min), pH (3–10), initial arsenic concentration (25–100 μg/L), initial nitrate concentration (60–120 mg/L) and adsorbent dose (0.25–5 mg/L) as various operating influences were investigated on the co-adsorption of arsenic and nitrate from water by a new nanocomposite thru diverse experimental tests. Characteristics of F-ZIF8@EMM were determined through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET) analyses. Taguchi model was used to determine the optimal co-adsorption conditions. The results revealed that the optimal conditions for the simultaneous adsorption of 94.32 % of these two elements were at pH = 7, adsorbent dose 1 mg/L, primary nitrate concentration 120 mg/L, initial arsenic concentration 100 μg/L, and contact time 90 min. Correspondingly, the simultaneous adsorption of arsenic and nitrate best fit the Langmuir isotherm, and the pseudo-second-order (PSO) model was the best model that fitted with experimental kinetic data (R2 = 1). The maximum experimental adsorption capacity of F-ZIF8@EMM was 128.5 mg/g. This study indicated that the efficiency of nanocomposite F-ZIF8@EMM in the co-adsorption of arsenic and nitrate was promising.

Spontaneous Photonic Jammed Packing of Core-Shell Colloids in Conductive Aqueous Inks for Non-Iridescent Structural Coloration.

Integrating structural colors and conductivity into aqueous inks has the potential to revolutionize wearable electronics, providing flexibility, sustainability, and artistic appeal to electronic components. This study aims to introduce bioinspired color engineering to conductive aqueous inks. Our self-assembly approach involves mixing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with sulfonic acid-modified polystyrene (sPS) colloids to generate non-iridescent structural colors in the inks. This spontaneous structural coloration occurs because PEDOT:PSS and sPS colloids can self-assemble into core-shell structures and reversibly cluster into photonic aggregates of maximally random jammed packing within the aqueous environment, as demonstrated by small-angle X-ray scattering. Dissipative particle dynamics simulation confirms that the self-assembly aggregation of PEDOT:PSS chains and sPS colloids can be manipulated by the polymer-colloid interactions. Utilizing the finite-difference time-domain method, we demonstrate that the photonic aggregates of the core-shell colloids achieve close to maximum jammed packing, making them suitable for producing vivid structural colors. These versatile conductive inks offer adjustable color saturation and conductivity, with conductivity levels reaching 36 S cm-1 through the addition of polyethylene glycol oligomer, while enhanced water resistance and mechanical stability are achieved by doping with a cross-linker, poly(ethylene glycol) diglycidyl ether. With these unique features, the inks can create flexible, patterned circuits through processes like coating, writing, and dyeing on large areas, providing eco-friendly, visually appealing colors for customizable, stylish, comfortable, and wearable electronic devices.

Robust Imidazopyridinium Covalent Organic Framework as Efficient Iodine Capturing Materials in Gaseous and Aqueous Environment.

The development of a high-performing adsorbent that can capture both iodine vapor from volatile nuclear waste and traces of iodine species from water is an important challenge, especially in industrially relevant process conditions. This study introduces novel imidazopyridinium-based covalent organic frameworks (COFs) through post-modification of a picolinaldehyde-based imine COF. These COFs demonstrate excellent iodine adsorption capacity, adsorption kinetics, and a high stability/recyclability in both vapor and water phases. Notably, one imidazopyridinium COF exhibits gaseous iodine uptake of 21wt.% under dynamic adsorption conditions at 150°C and a relative humidity of 50%, surpassing the performance of the currently used silver-based zeolite adsorbents (Ag@MOR (17wt.%)). Additionally, the same imidazopyridinium COFs can efficiently remove iodine species at a low concentration from aqueous solution. Seawater containing triiodide ions treated under dynamic flow-through conditions resulted in decreased concentrations down to the ppb level. The adsorption mechanisms for iodine and polyiodide species are elucidated for the imine COF and imidazopyridinium COFs; involving halogen bonding, hydrogen bonding, and charge-transfer complexes.

Iron-copper bimetallic photo-Fenton system promoted photothermal-hydrogen peroxide production for efficient low-temperature wastewater treatment

Enhancing the velocity of the oxidation–reduction cycle is crucial for improving the catalytic efficiency of Fenton processes. Therefore, the development of an effective strategy for wastewater degradation at low temperatures is essential. In this context, we present the preparation of an NH2-MIL-88B (Fe)/CuInS2 S-scheme heterojunction. Specifically, CuInS2 nanoparticles are introduced onto the Ferro-organic skeleton, resulting in the exposure of a significant number of active surface sites. Furthermore, NH2-MIL-88B (Fe)/CuInS2 demonstrates an extended photoresponse into the long-wavelength region, which contributes to its excellent photothermal properties. Notably, the degradation rate of tetracycline in low-temperature aqueous environments reaches as high as 99.7 %, several times higher than that of the original sample. Additionally, the hydrogen production of NH2-MIL-88B (Fe)/CuInS2 is 2.23 times that of single NH2-MIL-88B (Fe) and 3.46 times that of single CuInS2. Moreover, the system exhibits good H2O2 evolution performance, forming an efficient photo-Fenton system. The charge transfer process in S-scheme heterojunction is confirmed using in-situ X-ray photoelectron spectroscopy and electron paramagnetic resonance. Both transient photoluminescence and photo electrochemical tests further validate the enhanced photoelectrochemical properties of the NH2-MIL-88B (Fe)/CuInS2 S-scheme heterojunction. The exceptional performance of this system can be attributed to the synergistic effects of the S-scheme heterojunction and the bimetallic codoped photo-Fenton system. This research presents a novel approach for the breakdown of low-temperature wastewater using an improved photocatalytic Fenton system.

Exploring the efficiency of nitrogenated carbon quantum dots/TiO2 S-scheme heterojunction in the photodegredation of ciprofloxacin in aqueous environments.

In this study, we developed a heterojunction photocatalyst, namely nitrogen-doped carbon quantum dots/titanium dioxide (N-CQDs/TiO2), for the effective and sustainable treatment of ciprofloxacin (CIP) antibiotic in aqueous solution. First, N-CQDs were prepared from a chitosan biopolymer with a green, facile, and effective hydrothermal carbonization technique and then anchored on the TiO2 surface via a hydrothermal process. The morphological, structural, and optical properties of the as-prepared materials were characterized by using advanced analytical techniques. The impacts of the mass percentage of N-CQDs, catalyst and CIP concentration, and pH on photocatalytic CIP degradation were investigated in depth. Comparative analyses were performed to evaluate different processes including adsorption, photolysis, and photocatalysis for the removal of CIP with TiO2 and N-CQDs/TiO2. The results revealed that N-CQDs/TiO2 exhibited the highest CIP removal efficiency of up to 83.91% within 120 min using UVA irradiation under optimized conditions (10 mg/L CIP, 0.4 g/L catalyst, and pH 5). Moreover, the carbon source used in the fabrication of N-CQDs was also considered, and lower removal efficiency was obtained when glucose was used as a carbon source instead of chitosan. This excellent improvement in CIP degradation was attributed to the ideal separation and migration of photogenerated carriers, strong redox capability, and high generation of reactive oxygen species provided by the successful construction of the N-CQDs/TiO2 S-scheme heterojunction. Scavenger experiments indicated that h+ and •OH reactive oxygen species were the predominant factors for CIP elimination in water. Overall, this study presents a green synthesis approach for N-CQDs/TiO2 heterojunction photocatalysts using natural materials, demonstrating potential as a cost-effective and efficient method for pharmaceutical degradation in water treatment applications.

Light Switchable Bioorthogonal Reaction Manifold for Modulation of Hydrogel Properties.

Chemical reaction systems that can occur via multiple pathways in a controllable fashion are highly attractive for advanced materials applications and biological research. In this report, we introduce a bioorthogonal reaction manifold based on a chalcone pyrene (CPyr) moiety that can undergo either red-shifted photoreversible [2 + 2] cycloaddition or thiol-Michael addition click reaction. By coupling the CPyr to a water-soluble poly(ethylene glycol) end group, we demonstrate the efficient polymer dimerization and cleavage by blue light (λ = 450 nm) and UV light (λ = 340 nm), respectively. In the absence of light, CPyr rapidly reacts with thiols in aqueous environments, enabling fast and efficient polymer end-group functionalization. The chemical reaction manifold was further employed in polymer cross-linking for the preparation of hydrogels whose stiffness and morphology can be modulated by different photonic fields or the addition of a thiol cross-linker. The photoreversible cycloaddition and thiol-Michael addition click reaction can be used in conjunction for spatial and temporal conjugation of a streptavidin protein. Both cross-linking conditions are nontoxic to various cell lines, highlighting their potential in biomaterials applications.

Adsorption of ciprofloxacin from aqueous solutions using cellulose-based adsorbents prepared by sol-gel method

Ciprofloxacin (CIP) is one of the most widely used antibiotics to treat bacterial infections. Consequently, there is concern that it may contaminate water resources due to its high usage level. It is therefore necessary to monitor, trace, and reduce exposure to these antibiotic residues. In the current study, the extraction of CIP from water was performed using a green adsorbent material based on cellulose/polyvinyl alcohol (PVA) decorated with mixed metal oxides (MMO). This cellulose/MMO/PVA adsorbent was synthesized using a simple sol-gel method. The prepared adsorbent materials were then characterized using a range of methods, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, gas adsorption analysis, X-ray diffraction, and Fourier Transform infrared. The impact of pH, adsorbent dose, contact time, and CIP concentration on ciprofloxacin extraction were examined. The equilibrium and kinetic adsorption data were well described using the Freundlich model (R2 = 0.965). The optimum conditions for CIP adsorption were: pH = 4.5; adsorbent dosage = 0.55 g·L−1; contact time = 83 min; and initial CIP concentration = 2 mg·L−1. The adsorption capacity of the cellulose/MMO/PVA adsorbent for CIP removal was ∼19 mg·g−1 (CIP removal = 86.48 %). This study shows that cellulose/MMO/PVA adsorbents have potential for removing contaminants from aqueous environments.

Toxicity of Moxifloxacin on the Growth, Photosynthesis, Antioxidant System, and Metabolism of Microcystis aeruginosa at Different Phosphorus Levels.

Moxifloxacin (MOX), a widely used novel antibiotic, may pose ecological risks at its actual environmental concentrations, as has been detected in aquatic systems. However, its ecotoxicity to aquatic organisms and regulatory mechanisms of phosphorus in eutrophic aqueous environments are still limited. This study aimed to analyze its physiological and biochemical parameters, including cellular growth, chlorophyll fluorescence, photosynthetic pigments, oxidative stress biomarkers, and metabolomics to elucidate the toxicity induced by environmental concentrations of MOX in Microcystis aeruginosa at different phosphorus levels. The results revealed that the EC50 values of MOX on M. aeruginosa at different phosphorus concentrations were 8.03, 7.84, and 6.91 μg/L, respectively, indicating MOX toxicity was exacerbated with increasing phosphorus levels. High phosphorus intensified the suppression of chlorophyll fluorescence and photosynthetic pigments, while activating the antioxidant enzyme, indicating severe peroxidation damage. Metabolomic analysis showed MOX induced different discriminating metabolites under different phosphorus levels, and perturbed more biological pathways at higher phosphorus concentrations, such as starch and sucrose metabolism, pyrimidine metabolism, and glycerolipid metabolism. This indicates that phosphorus plays an important role in regulating metabolism in M. aeruginosa exposed to MOX. The findings provide valuable information on the mechanisms involved in cyanobacteria responses to antibiotic stress, and offer a theoretical basis for accurately assessing antibiotic toxicity in eutrophic aqueous environments.

New Mn Electrochemistry for Rechargeable Aqueous Batteries: Promising Directions Based on Preliminary Results

Aqueous batteries with metal anodes exhibit robust anodic capacities, but their energy densities are low because of the limited potential stabilities of aqueous electrolyte solutions. Current metal options, such as Zn and Al, pose a dilemma: Zn lacks a sufficiently low redox potential, whereas Al tends to be strongly oxidized in aqueous environments. Our investigation introduces a novel rechargeable aqueous battery system based on Mn as the anode. We examine the effects of anions, electrolyte concentration, and diverse cathode chemistries. Notably, the ClO4‐based electrolyte solution exhibits improved deposition and dissolution efficiencies. Although stainless steel (SS 316 L) and Ni are stable current collectors for cathodes, they display limitations as anodes. However, using Ti as the anode resulted in increased Mn deposition and dissolution efficiencies. Moreover, we evaluate this system using various cathode materials, including Mn‐intercalation‐based inorganic (Ag0.33V2O5) and organic (perylenetetracarboxylic dianhydride) cathodes and an anion‐intercalation‐chemistry (coronene)‐based cathode. These configurations yield markedly higher output potentials compared to those of Zn metal batteries, highlighting the potential for an augmented energy density when using an Mn anode. This study outlines a systematic approach for use in optimizing metal anodes in Mn metal batteries, unlocking novel prospects for Mn‐based batteries with diverse cathode chemistries.

In-Situ Generation of Hydrogen Polysulfides (H2Sn) with Thioglucose, Glucose Oxidase, and Chloroperoxidase.

Hydrogen polysulfides (H2Sn) have emerged as critical physiological mediators that are closely associated with hydrogen sulfide (H2S) signaling. H2Sn exhibit greater nucleophilicity than H2S while also having electrophilic characteristics, enabling unique activities such as protein S-persulfidation. Despite their physiological importance, mechanisms and reactivities of H2Sn remain inadequately explored due to their inherent instability in aqueous environments. Consequently, there is a need to develop biocompatible methods for controlled H2Sn generation to elucidate their behaviors in biological contexts. Herein, we present a dual enzyme system (containing glucose oxidase (GOx) and chloroperoxidase (CPO)) with thioglucose as the substrate to facilitate the controlled release of H2Sn. Fluorescence measurements with SSP4 and the trapping studies allowed us to confirm the production of H2Sn. Such a method may be useful in elucidating the reactivity of hydrogen polysulfides in biological systems as well as provide a potential delivery of H2Sn to target sites for biological applications.

99mTc(I)-Labeled His-Tagged Proteins: Impact in the Development of Novel Imaging Probes and in Drug Discovery.

Technetium-99m (99mTc) remains the cornerstone of nuclear medicine for single photon emission computed tomography (SPECT) due to its widespread availability and chemical and physical features. Its multiple oxidation states allow for the design and production of radiopharmaceuticals with versatile properties, namely in terms of pharmacokinetic profile. 99mTc(V) is the most common oxidation state, but 99mTc(I) gained traction after the pioneering work of Alberto and colleagues, which resulted in the introduction of the organometallic core fac-[99mTc(CO)3(H2O)3]+. This core is readily available from [99mTcO4]- and displays three labile water molecules that can be easily swapped for ligands with different denticity and/or donor atoms in aqueous environment. This makes it possible to radiolabel small molecules as well as high molecular weight molecules, such as antibodies or other proteins, while assuring biological activity. Direct radiolabelling of those proteins with fac-[99mTc(CO)3]+ under mild conditions is accomplished through incorporation of a polyhistidine tag (His-tag), a commonly used tag for purification of recombinant proteins. This review aims to address the direct radiolabelling of His-tagged macromolecules with fac-[99mTc(CO)3]+ for development of molecular imaging agents and the impact of this technology in the discovery and development of imaging and/or therapeutic agents towards clinical application.

Aqueous‐Phase Preparation of Core–Shell Perovskite Nanorods Encapsulated in Polydopamine with Ultrahigh Water Stability

All‐inorganic perovskite CsPbBr3 (CPB) nanocrystals (NCs) are not widely applied in aqueous environments due to their readily decomposable nature. Therefore, the aqueous‐phase preparation of CPB NCs has been a considerable challenge. In this work, a feasible method is proposed for preparing aqueous‐phase core–shell CPB nanorods (NRs) encapsulated with polydopamine (PDA) by employing a multifunctional additive cesium trifluoroacetate (Cs‐TFA). Highly luminescent TFA‐CPB NRs are obtained via a chemical transformation of Cs4PbBr6 NCs in water. Subsequently, PDA constitutes a robust shell on the surface of TFA‐CPB NRs through the covalent oxidative polymerization, which effectively reduces the original dynamic properties of surface ligands, retards the decomposition of ligands and inhibits the leakage of Pb2+ ions. The results demonstrate that the fluorescence intensity of TFA‐CPB@PDA NRs maintains 49.3% of the initial intensity after 136 days. Meanwhile, the NRs exhibit low cytotoxicity, and the cell viability remains at 80% when the concentration of the NRs is 200 μg mL−1. The reliable preparation of aqueous‐phase core–shell perovskite NRs (PNRs) will facilitate their development in many fields, such as materials science, biology, medicine, and their applications in aqueous environments.