Complex Aqueous Media Research Articles

Macromolecular hydrogels for the colorimetric detection and efficient separation of cobalt (II) in complex aqueous media

Azobenzene quinolinol–based hydrogels were developed for the highly selective detection and separation of Co(II) ions in complex aqueous media. (E)-2-((4-(Diazenyl(8-hydroxyquinolin-5-yl))phenyl)(methyl)amino)ethyl acrylate (DHPMAA) and N,N-dimethylacrylamide (DMA) were copolymerized to yield p(DMA-co-DHPMAA). The polymeric probe exhibited high selectivity and sensitivity toward Co(II) ions in aqueous solutions. Hydrogels based on p(DMA-co-DHPMAA) were synthesized via photopolymerization and were demonstrated to effectively separate Co(II) ions from various other metal ions. The selectivity was further demonstrated under challenging conditions in which the concentration of Fe(II) ions substantially exceeded that of Co(II) ions, simulating radioactive waste in cooling channels of nuclear power plants. The synthesized hydrogels were able to selectively separate Co(II) ions from a complex mixture containing excess Fe(II) ions at a concentration five times that of the Co(II) ions, demonstrating the application potential of the hydrogels for Co(II) ions removal.

Ultrasensitive Ratiometric Electrochemiluminescence Sensor with an Efficient Antifouling and Antibacterial Interface of PSBMA@SiO2-MXene for Oxytetracycline Trace Detection in the Marine Environment.

The sensitivity and accuracy of electrochemiluminescence (ECL) sensors for detecting small-molecule pollutants in environmental water are affected not only by nonspecific adsorption of proteins and other molecules but also by bacterial interference. Therefore, there is an urgent need to develop an ECL sensor with antifouling and antibacterial functions for water environment monitoring. Herein, a highly efficient antifouling sensing interface (PSBMA@SiO2-MXene) based on zwitterionic sulfobetaine methacrylate (SBMA) antifouling nanospheres (NPs) and two-dimensional MXene nanosheets was designed for the sensitive detection of oxytetracycline (OTC), an antibiotic small-molecule pollutant. Specifically, SBMA with good hydrophilicity and electrical neutrality was connected to SiO2 NPs, thus effectively reducing protein and bacterial adsorption and improving stability. Second, MXene with a high specific surface area was selected as the carrier to load more antifouling NPs, which greatly improves the antifouling performance. Meanwhile, the introduction of MXene also enhances the conductivity of the antifouling interface. In addition, a ratio-based sensing strategy was designed to further improve the detection accuracy and sensitivity of the sensor by utilizing Au@luminol as an internal standard factor. Based on antifouling and antibacterial interfaces, as well as internal standard and ratiometric sensing strategies, the detection range of the proposed sensor was 0.1 ng/mL to 100 μg/mL, with a detection limit of 0.023 ng/mL, achieving trace dynamic monitoring of antibiotics in complex aqueous media.

Al3+-Responsive Ratiometric Fluorescent Sensor for Creatinine Detection: Thioflavin-T and Sulfated-β-Cyclodextrin Synergy.

Kidney disorders are a rising global health issue, necessitating early diagnosis for effective treatment. Creatinine, a metabolic waste product from muscles, serves as an ideal biomarker for kidney damage. The existing optical methods for creatinine detection often involve labor-intensive synthesis processes and present challenges with the aqueous solubility and sensitivity to experimental variations. In this study, we introduce a straightforward fluorescence "turn-on" ratiometric sensor system for creatinine detection in aqueous media with a limit of detection of 0.5 μM. The sensor is based on sulfated-β-cyclodextrin (SCD)-templated H-aggregate of a commercially available, ultrafast rotor dye thioflavin-T (ThT). The Al3+ ion-induced dissociation of ThT-SCD aggregates, followed by reassociation upon creatinine addition, generates a detectable signal. The modulation of monomer/aggregate equilibrium due to the disassembly/reassembly of the ThT-SCD system under Al3+/creatinine influence serves as the optimal strategy for ratiometric creatinine detection in aqueous media. Our sensor framework offers several advantages: utilization of the readily available dye ThT, which eliminates the need for a laborious synthesis of custom fluorescent probes; ratiometric sensing, which improves quantitative analysis accuracy; and compatibility with complex aqueous media. The sensor's practical utility has been successfully demonstrated in artificial urine samples. In summary, our sensor system represents a significant advancement in the rapid, selective, and sensitive detection of the clinically crucial bioanalyte creatinine, offering potential benefits for the early diagnosis and management of kidney disorders.

Kinetically Inert Macrocyclic Europium(III) Receptors for Phosphate.

The significant role that phosphate plays in environmental water pollution and biomedical conditions such as hyperphosphatemia highlights the need to develop robust receptors that can sequester the anion effectively and selectively from complex aqueous media. Toward that goal, four macrocyclic tris-bidentate 1,2-hydroxypyridonate (HOPO) europium(III) complexes containing either a cyclen, cyclam, TACN, or TACD ligand cap were synthesized and evaluated as phosphate receptors. The solubility of EuIII-TACD-HOPO in water was insufficient for luminescent studies. Whereas EuIII-cyclen-HOPO is eight coordinate with two inner-sphere water molecules, both EuIII-cyclam-HOPO and EuIII-TACN-HOPO are nine coordinate with three inner-sphere water molecules, suggesting that the two coordination states are very close in energy. As observed previously with linear analogues of tripodal HOPO complexes, there is no relationship between the number of inner-sphere water molecules and the affinity of the complex for phosphate. Whereas all three complexes do bind phosphate, EuIII-cyclen-HOPO has the highest affinity for phosphate with the anion displacing both of its inner-sphere water molecules. On the other hand, only one or two of the three inner-sphere water molecules of EuIII-TACN-HOPO and EuIII-cyclam-HOPO are displaced by phosphate, respectively. All three complexes are highly selective for phosphate over other anions, including arsenate. All three complexes are highly stable. EuIII-cyclen-HOPO and, to a lesser extent, EuIII-TACN-HOPO are more kinetically inert than the linear EuIII-Ser-HOPO. EuIII-cyclam-HOPO, on the other hand, is not. This study highlights the significant effect that minor changes in the ligand cap can have on both the ligand exchange rate and affinity for phosphate of tripodal 1,2-dihydroxypyridinonate complexes.

Molecularly imprinted catalytic membrane reactor for improved advanced oxidation degradation efficiency of low concentration pollutants

Improving the efficiency of advanced oxidation technology to remove low concentration pollutants is one of the important problems in water treatment. In this study, a molecularly imprinted catalytic membrane (MICM) reactor has been designed and developed to solve this problem. The results showed that the MICM rapidly separated and degrade refractory pollutants in complex aqueous media, while significantly improving oxidation efficiency. Compared to Fe3O4, rate constants on the MICM in three different systems were significantly increased 3.5–33-fold, with kobs in persulfate (PS), hydrogen peroxide (H2O2), and peroxymonosulfate (PMS) oxidation systems reaching 0.093 min−1, 0.073 min−1, and 0.142 min−1, respectively. The results of dynamic experiments showed that sulfamethoxazole (SMX) removal efficiencies in MICM/PMS and H2O2 oxidation systems could exceed 90% within 150 min. Studies have shown that the targeting catalysis process of the MICM benefited from a coupling effect, which endows the MICM with stronger hydrophilicity and superior stability. Based on detection results and kinetic calculations, MICMs could not only selectively identify target pollutants, but also adsorb oxidants to promote non-free radical reactions represented by 1O2 in PMS oxide process. This enabled more efficient contact between the oxidant, the targeted pollutant, and the catalytic core of the MICM, increasing the oxidation efficiency. This study may provide reference for improving the efficiency of advanced oxidation processes and the application of molecularly imprinted catalysts.

β-cyclodextrin-based porous carbon with tunable pore and interface allows efficient removal of chlorophenols from aqueous solution

Chlorophenols (CPs), a kind of important intermediate for fine chemicals, exists widely in the aqueous environment and poses a significant danger to humans. Therefore, developing advanced materials to enable the effective capture of CPs is highly desired. Herein, β-cyclodextrin-based porous carbon (CPAC) with exceptional capacities for CPs has been designed and tested. These porous carbon adsorbents were successfully synthesized via stepwise carbonization, affording abundant N and O functional groups, high surface area (as high as 3982 m2·g−1) and controlled pore size to optimize for rapid CPs uptake. According to the CPs uptake measurements, CPAC exhibited exceptional CPs adsorption performance. CPAC showed high adsorption capacities (1085.08 mg·g−1 for 2,4,6-trichlorophenol) and fast adsorption kinetics for CPs. CPAC can effectively recover multi-component CPs from complex aqueous media, and the special pore structure reduces the competitive adsorption between CPs. And the recyclability studies showed that CPAC maintained its structural integrity and the initial CPs uptake capacity, highlighting its potential for practical application. Besides, DFT calculations indicate that hydrogen bonding and π-π interactions are key factors. Among them, the molecular conformation of CPs and the number of chlorine atoms on phenol play a crucial role in the adsorption behavior and adsorption energy.

Rational Design of the β‐Bulge Gate in a Green Fluorescent Protein Accelerates the Kinetics of Sulfate Sensing**

AbstractDetection of anions in complex aqueous media is a fundamental challenge with practical utility that can be addressed by supramolecular chemistry. Biomolecular hosts such as proteins can be used and adapted as an alternative to synthetic hosts. Here, we report how the mutagenesis of the β‐bulge residues (D137 and W138) in mNeonGreen, a bright, monomeric fluorescent protein, unlocks and tunes the anion preference at physiological pH for sulfate, resulting in the turn‐off sensor SulfOFF‐1. This unprecedented sensing arises from an enhancement in the kinetics of binding, largely driven by position 138. In line with these data, molecular dynamics (MD) simulations capture how the coordinated entry and gating of sulfate into the β‐barrel is eliminated upon mutagenesis to facilitate binding and fluorescence quenching.

Rational Design of the β-Bulge Gate in a Green Fluorescent Protein Accelerates the Kinetics of Sulfate Sensing.

Detection of anions in complex aqueous media is a fundamental challenge with practical utility that can be addressed by supramolecular chemistry. Biomolecular hosts such as proteins can be used and adapted as an alternative to synthetic hosts. Here, we report how the mutagenesis of the β-bulge residues (D137 and W138) in mNeonGreen, a bright, monomeric fluorescent protein, unlocks and tunes the anion preference at physiological pH for sulfate, resulting in the turn-off sensor SulfOFF-1. This unprecedented sensing arises from an enhancement in the kinetics of binding, largely driven by position 138. In line with these data, molecular dynamics (MD) simulations capture how the coordinated entry and gating of sulfate into the β-barrel is eliminated upon mutagenesis to facilitate binding and fluorescence quenching.

Interactions of Ti3C2 MXene with Aqueous Zwitterionic Biological Buffers: Implications for Applications in Biological Systems

MXenes, a family of ultrathin layered two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides, are steadily advancing as novel inorganic nanosystems for a broad range of applications. While high conductivity, solution processability, hydrophilic nature, and the presence of various surface functional groups enable the use of 2D MXenes in aqueous systems, applications that involve the use of MXenes in aqueous systems and biological solutions, including but not limited to water treatment, water desalination, and biological assays, are only beginning to emerge. For the successful application of MXene in aqueous systems, their interactions with common aqueous solution constituents must be better understood. This paper describes the structural and functional properties of Ti3C2Tx (Tx = O−, OH−, F−) MXenes in N-substituted commonly used biological buffers like N-(2-hydroxyethyl)-piperazine-N′-ethanesulfonic acid (HEPES) and 3-(N-morpholino)-propane sulfonic acid (MOPS) and with a series of piperazine-based molecules dissolved in phosphate buffer solutions. Dissolving MXenes in these buffers significantly impacts their optical, structural, and electrical properties. The interactions of Ti3C2Tx MXenes with N-substituted zwitterionic buffer molecules are structure-dependent and mostly but not fully reversible. X-ray photoelectron spectroscopy measurements reveal small but measurable surface oxidation through the formation of Ti–O bonds. Our results suggest a complex interaction pattern where some interactions are driven by hydrogen bonding and electrostatic forces, while others involve chemisorption, which results in a permanent impact on the MXene nanosheets. This study is an important step toward understanding the stability of MXenes in complex aqueous media and the impact of interactions of MXenes with nitrogen-containing molecules on MXene properties, which are especially important in applications of MXenes in biological systems. The nature of interactions between MXenes and biological buffer molecules, revealed in our study, suggests that surface chemistry modifications of MXenes are required to preserve their chemical stability and enable their applications in complex biological solutions.

Simultaneous and efficient removal of heavy metal ions and organophosphorus by amino-functionalized cellulose from complex aqueous media

Electroless plating occupies a vital position in the fields of metal anticorrosion while accompanied by a large amount of effluent containing organophosphorus (like phytic acid) and heavy metals ions {like Cu (II) and Ni (II)}. However, it was still remaining great challenges in how to simultaneously remove these organophosphorus and heavy metal ions with simple methods. This work prepared a green, clean and efficient adsorbent amino-functionalized cellulose (AFCA) for simultaneous removal of organophosphorus and metal ions from complex wastewater. Benefitting from its abundant amino groups, AFCA can rapidly remove organophosphorus and metal ions within 10 min. The theoretical maximum adsorption capacities of AFCA could also reach as high as 89.29 mg/g, 79.37 mg/g and 178.57 mg/g, respectively. Most importantly, for the mixed system of organophosphorus and Cu (II), the removal efficiency was increased by 5.66% and 30.23% compared with the individual system, respectively. High simultaneous removal capacity of AFCA was due to the hydrogen bond and electrostatic interactions with organophosphorus and the complexation interactions between abundant amino groups and metal ions. All of these results demonstrate that AFCA has enormous potential for the treatment of actual electroless plating effluents.

Luminescent Lanthanide Probes for Inorganic and Organic Phosphates.

Inorganic and organic phosphates‐including orthophosphate, nucleotides, and DNA‐are some of the most fundamental anions in cellular biology, regulating numerous processes of both medical and environmental significance. The characteristic long lifetimes of emitting lanthanides, including the brighter europium(III) and terbium(III), make them ideally suited for the development of molecular probes for the detection of phosphates directly in complex aqueous media. Moreover, given their high oxophilicity and the exquisite sensitivity of their quantum yields to their hydration number, those luminescent lanthanides are perfect for the detection of phosphates. Herein we discuss the principles that have guided the recent developments of molecular probes selective for inorganic or organic phosphates and how these lanthanide complexes facilitate the study of numerous biological processes.

Bacterial cellulose hybrid membrane grafted with high ratio of adipic dihydrazide for highly efficient and selective recovery of gold from e-waste

To solve metal resource shortage and alleviate environmental issues, it is in urgent need to explore cost-effective and environment-friendly adsorbents for sustainable recovery of valuable gold from e-waste. Herein, bacterial cellulose (BC) hybrid membrane grafted with adipic dihydrazide (ADH) has been fabricated via a facile schiff base reaction strategy for efficient and selective recovery of gold from complex aqueous media. The resulting ADH@BC hybrid membrane features high ratio of hydrazide groups (67% of ADH by mass content) and hierarchical porous structure, ensuring high adsorption capacity (1149 mg/g) and fast adsorption equilibrium time (20 min) toward gold. Meanwhile, the remarkable recovery selectivity of gold is achieved in the simulated e-waste leachate containing a large amount of interfering metal ions. Notably, the captured Au(III) species on ADH@BC hybrid membrane can be directly converted by redox-active hydrazide groups into Au(0) with no need of any external reductant. Furthermore, the developed ADH@BC membrane possesses superior recycling and reusability performance, as reflected by no obvious decrease in gold extraction capability after six cycles. More importantly, the ADH@BC hybrid membrane is capable of extracting almost 100% of gold from actual waste central processing unit (CPU) leachate, yielding high-purity gold (23.7 K) after pyrolysis.

A universal automated method for determining the bacteriostatic activity of nanomaterials

The lack of analytical strategies to directly determine the bacteriostatic activity of nanomaterials in complex aqueous media (e.g., environmentally relevant scenarios) seriously hampers the harvest of reliable data for nanomaterial risk assessment. Here, we created an automated phenotypic method based on a developed multi-channel contactless conductometric sensor. Bacterial growth kinetics of E. coli and S. aureus were determined via on-line monitoring of conductivity changes in simple media (e.g., liquid LB broth) and complex media (e.g., relevant river water and seawater samples with diverse pH, salinity, conductivity, turbidity, chemical oxygen demand and total suspended solids). The high temporal resolution growth curves provide detailed information on the bacteria inhibition of the model nanomaterial - Au nanospheres, Au nanorods, Ag nanospheres and Ag nanocubes - at each growth stage, thus enabling users to directly obtain minimum inhibitory concentrations. The method highlights the advantages of universality, simplicity and affordability. It opens up possibilities for the development of a powerful analytical platform for researches in the field of nanoscience, e.g. to assess ecotoxicity of nanomaterials.

Small and Bright Water-Protected Upconversion Nanoparticles with Long-Time Stability in Complex, Aqueous Media by Phospholipid Membrane Coating.

Chemical and colloidal stability in complex aqueous media are among the main challenges preventing nanoparticles from successfully entering into the biomedical field. Small core-shell upconversion nanoparticles (UCNPs) NaYF4:Yb,Er@NaYF4 of 12 nm in diameter with a high surface-to-volume ratio are utilized to demonstrate that self-assembling phospholipid bilayers (PLMs) have several benefits compared to common ligand-exchange and ligand-addition particle coatings such as poly(acrylic acid) and amphiphilic polymers. An efficient hydrophobic barrier against water quenching and toward particle disintegration is formed by PLM. Particles with this functionalization have a higher upconversion luminescence in aqueous media in contrast to common surface ligands. They attract with better colloidal stability in phosphate buffer, in a wide pH range, in high ionic solutions, and in complex cell media, as is required for biological applications. Moreover, kidney cells (NRK) are not affected by these stable PLM-coated UCNPs as first cell viability tests reveal.

Synthesis and adsorption behavior of a magnetic ZSM zeolite for the selective removal of p-xylene from complex aqueous media

• Molecular simulation was adopted to ascertain the suitable template. • Highly selective adsorption of PX was got by using magnetic ZSM-5 as adsorbents. • Adsorption performance of PX on magnetic H-ZSM-5 was better than formed H-ZSM-5. • Adsorption behaviors of PX on Magnetic ZSM-5 zeolites were investigated. Abstract The commonly adsorbents used must to be formed and their adsorption efficiencies greatly decrease after molding. Consequently, magnetic ZSM-5 was synthesized for the selective adsorption of p-xylene (PX) from industrial wastewater with tetrapropyl ammonium (TPA + ) as an appropriate template. The prepared magnetic ZSM-5 has good magnetic separation performance and selective adsorption capacity for PX. The adsorption process of PX on magnetic ZSM-5 was a physical adsorption, exothermic and entropy reduction process, which could be more accurately described by the Langmuir isothermal adsorption model and the pseudo-second-order equation. The adsorption process was jointly controlled by film diffusion and intraparticle diffusion.

Selective Capture and in Situ Controllable Detection of d-Glucose in Cerebral Systems.

To monitor d-glucose (Glu) in complex aqueous media with a high specificity, a conceptually new "selective capture and controllable detection" nanoreactor was explored. We designed and synthesized poly maleic anhydride-styrene-N-isopropylacrylamide-(4-aminophenyl) boronic acid [P(MAn-St-NIPAm-PBA)] to fabricate the nanoreactor. On the surface of the self-assembled, micelle-based nanoreactor, the stereo precise placement PBA provided a recognition unit in the block copolymer structure to boost the selective capture of Glu over other saccharides. P(MAn-St-NIPAm) served as the thermal sensitive moiety of the nanoreactor, which embedded with glucose oxidase and myoglobin-based catalyst in order to realize the controllable enzymolysis of Glu through temperature alteration. Once the nanoreactor was mixed with Glu, an obvious change in the UV-visible intensity of quinine produced in the multienzymolysis was observed. Glu in the rat microdialysates of brain ischemia was successfully monitored by the nanoreactor method, demonstrating the feasibility of constructing high-specificity nanoreactors for cerebral system applications.

Challenges and opportunities at the nexus of energy, water, and food: A perspective from the southwest United States

ABSTRACT

Metal-assisted selective recognition of biothiols by a synthetic receptor array.

A synergistic combination of a deep cavitand host, fluorophore guests and transition metal ions can be used to sense small molecule thiols of biological interest with good efficiency and selectivity in complex aqueous media.

Probing interactions between sphalerite and hydrophobic/hydrophilic surfaces: Effect of water chemistry

Due to the limited availability of fresh water sources, recycled water and sea water, generally with high salinity, have been widely used in mining industry in arid regions, which can significantly affect the interactions of mineral particles, chemical additives and air bubbles in mineral processing (e.g., flotation). In this work, the surface forces and interaction mechanism of Si3N4 tip and a model mineral (i.e. sphalerite) in various aqueous solution conditions have been studied using an atomic force microscope (AFM). The Si3N4 tip was functionalized with octadecyltrichlorosilane (OTS) to tune the surface hydrophobicity. The sphalerite substrate was either freshly cleaved or treated with conditioning solutions: activator (i.e. CuSO4) and collector (i.e. potassium amyl xanthate, PAX) in various background solutions (i.e., Milli-Q water, 0.46M NaCl, saline water to mimic diluted sea water/industrial process water). The force-separation profiles indicate that in addition to the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) interactions, hydration interaction plays an important role for the surface interaction in saline water (with addition of divalent cations, Ca2+ and Mg2+) at short separation distance, while hydrophobic force dominates the interaction when Si3N4 tip and sphalerite are both hydrophobized. The surface force measurements further demonstrate that solution salinity and presence of divalent cations can significantly influence the adhesion between particles. The micro-flotation tests of sphalerite and silica mixtures of varying surface hydrophobicity can be well interpreted by the force measurements. This work provides useful insights into the fundamental interaction mechanisms of suspended particles possessing different hydrophilic and hydrophobic characteristics in complex aqueous media.

Quantification of volatile-alkylated selenium and sulfur in complex aqueous media using solid-phase microextraction

Biologically produced volatile-alkylated Se and S compounds play an important role in the global biogeochemical Se and S cycles, are important constituents of odorous industrial emissions, and contribute to (off-)flavors in food and beverages. This study presents a fully automated direct-immersion solid-phase microextraction (DI-SPME) method coupled with capillary gas chromatography−mass spectrometry (GC/MS) for the simultaneous quantification of 10 volatile-alkylated Se and S compounds in complex aqueous media. Instrumental parameters of the SPME procedure were optimized to yield extraction efficiencies of up to 96% from complex aqueous matrices. The effects of sample matrix composition and analyte transformation during sample storage were critically assessed. With the use of internal standards and procedural calibrations, the DI-SPME−GC/MS method allows for trace-level quantification of volatile Se and S compounds in the ng/L range (e.g. down to 30ng/L dimethyl sulfide and 75ng/L dimethyl selenide). The applicability and robustness of the presented method demonstrate that the method may be used to quantify volatile Se and S compounds in complex aqueous samples, such as industrial effluents or food and beverage samples.