Superconductivity and Charge-Density-Wave-Like Transition in Th2Cu4As5.

We report the synthesis, crystal structure, and physical properties of a novel ternary compound, Th2Cu4As5. The material crystallizes in a tetragonal structure with lattice parameters a = 4.0639(3) Å and c = 24.8221(17) Å. Its structure can be described as an alternating stacking of fluorite-type Th2As2 layers with antifluorite-type double-layered Cu4As3 slabs. The measurement of electrical resistivity, magnetic susceptibility, and specific heat reveals that Th2Cu4As5 undergoes bulk superconducting transition at 4.2 K. Additionally, all these physical quantities exhibit anomalies at 48 K, accompanied by a sign change in the Hall coefficient, suggesting a charge-density-wave-like (CDW) phase transition. Drawing from both experimental data and band calculations, we propose that the superconducting and CDW-like phase transitions are, respectively, associated with the Cu4As3 slabs and the As plane in the Th2As2 layers.

Persistent Nocardia beijingensis infection in a patient with postoperative abscess and misuse of antibiotics in China.

Here we describe the first case of abscess infection caused by Nocardia beijingensis in China. The patient was immunocompetent but suffered from postoperative abscess for 6 years. This study highlights the necessity of long-term infected foci to be thoroughly examined to identify the pathogen, as well as the importance of accurate Nocardia identification and antimicrobial susceptibility tests for understanding the pathogen's epidemiology, clinical significance, and treatment strategy.

Magnetic carbon nanotube modified with polymeric deep eutectic solvent for the solid phase extraction of bovine serum albumin.

This article described the fabrication of novel magnetic carbon nanotube modified with polymeric deep eutectic solvent (M-CNT@PDES) and its application as extractant for the magnetic solid phase extraction (MSPE) of bovine serum albumin (BSA). The physicochemical properties and morphology of M-CNT@PDES were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermo-gravimetric analysis (TGA), zeta potentials, fourier transform infrared spectrometry (FT-IR) and transmission electron microscope (TEM). Afterwards, several parameters such as pH value, initial concentration of BSA, extraction time, ionic strength and extraction temperature were optimized. The results indicated that the modification of PDES significantly improved the extraction performance for BSA, and the maximum extraction capacity was 225.15 mg/g under the optimized conditions. In addition, 0.20 mol/L NaCl-PBS solution was chosen as the appropriate eluent, and favourable elution rate (81.22%) was obtained. Circular dichroism spectroscopy (CD) indicated that the secondary structure of BSA has not changed during extraction and elution. The regenerative experiment and application in real calf serum confirmed the outstanding durability and practical application ability of M-CNT@PDES. All of above verified that the proposed M-CNT@PDES coupled with MSPE method has great application potential for the pre-concentration of biomolecules.

A composite prepared from MnO2 nanosheets and a deep eutectic solvent as an oxidase mimic for the colorimetric determination of DNA.

A composite was fabricated from deep eutectic solvent and MnO2 nanosheets (DES/MnO2) and is shown to be a viable oxidase mimic. The property, morphology and composition of DES/MnO2 was characterized. DES/MnO2 displays oxidase-like activity and can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to form a blue product (oxTMB) with an absorption maximum at 652 nm. Due to the presence of the DES, the polyanionic and negatively charged DNA is easily adsorbed on the surface of the composite by hydrogen bonding and electrostatic interactions. This leads to the inhibition of the oxidase-mimicking activity of DES/MnO2. This finding was used to design a colorimetric method for the determination of DNA. The assay work in the 10-100 µg mL-1 DNA concentration range and has a detection limit of 0.37 µg mL-1. The inhibiting mechanism was further studied by zeta potential measurements, dynamic light scattering and transmission electron microscopy. The selectivity study shows the DES/MnO2-TMB system to be highly selective for DNA when compared with many proteins, carbohydrates, salts and amino acid. RNA, on the other hand, interferes. The real sample analysis result illustrates that the new method can be used for the detection of DNA in bovine whole blood. Graphical abstractA novel oxidase mimic based on deep eutectic solvent-functionalized MnO2 nanosheets was synthesized, which can directly catalyze oxidation of 3,3',5,5'-tetramethylbenzidine (TMB, colorless) to oxTMB (blue). A sensitive and convenient colorimetric strategy for visual detection of DNA was established through DES/MnO2-TMB sensing system.

A composite consisting of a deep eutectic solvent and dispersed magnetic metal-organic framework (type UiO-66-NH2) for solid-phase extraction of RNA.

A cactus-shaped magnetic composite was prepared for solid-phase extraction of RNA. It is composed of the metal organic framework UiO-66-NH2 that was modified with Fe3O4 nanoparticles. The composite was then dispersed in a lactic acid-based deep eutectic solvent (DES, Fe3O4-COOH@UiO-66-NH2@DES). The structures of the sorbents were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry and thermogravimetric analysis. The extraction performance of sorbents was optimized and the maximum extraction capacity reached 246 mg·g-1. Extraction is shown to mainly rely on chelation interaction, electrostatic interaction, hydrophobic interaction and hydrogen bonding interaction. The sorbent can selectively extract RNA over DNA, bovine hemoglobin and amino acids. Regeneration studies indicated that the sorbent can be re-used (after regenreation with DES) several times without obvious change of the extraction capacity. The successful extraction of RNA from yeast testified the practical application of the sorbent. Graphical abstractSchematic representation of the fabrication Fe3O4-COOH@UiO-66-NH2@DES, and its application in the magnetic solid phase extraction of RNA.

Ionic liquids skeleton typed magnetic core-shell molecularly imprinted polymers for the specific recognition of lysozyme.

The novel ionic liquids skeleton typed magnetic core-shell molecularly imprinted polymers (Fe3O4-COOH@IL-MIP) were firstly constructed with 1-vinyl-3-aminoformylmethyl imidazolium chloride ionic liquid ([VAFMIM]Cl-IL) modified magnetic particles as the substrate materials, [VAFMIM]Cl-IL as functional monomer, 1,6-hexanediyl-3,3'-bis-1-vinylimidazolium dichloride ionic liquid as cross-linker and Lysozyme (Lys) as template protein via surface-imprinting technique. The structure of Fe3O4-COOH@IL-MIP were confirmed by transmission and scanning electron microscopy, dynamic light scattering, thermo-gravimetric analysis, fourier transform infrared spectrometry and X-ray diffraction. The adsorption mechanism was discussed from the perspective of amino acid residues of Lys. The maximum adsorption capacity of MIPs was 166.36 mg g-1 and imprinting factor was 2.67. The competitive adsorption experiments demonstrated the favorable recognition ability of MIPs toward Lys. Reusability studies indicated MIPs can be reused ten times without obvious loss of rebinding ability. The Lys conformation maintained intact after elution and the elution rate was as high as 74%. The adsorption experiment of egg white manifested that MIPs can effectively separate Lys in practical samples. Only ILs and Fe3O4 were utilized to fabricate MIPs, this strategy realized the goal of energy and cost saving while achieving simple synthesis of imprinted materials, and is expected to provide a new feasible idea to exploit synthetic methods for protein-MIPs.

Development of deep eutectic solvent-based aqueous biphasic system for the extraction of lysozyme.

Aqueous Biphasic Systems (ABSs) based on deep eutectic solvents (DESs) were determined and applied in the extraction of lysozyme from chicken egg white. Tetrabutylammonium bromide (TBAB) and benzyltributylammonium bromide were utilized as hydrogen-bond acceptors to synthesize six kinds of DESs with different carboxylic acids (such as glycolic acid, Gly). The phase-formation ability of these DESs was evaluated by combining several salts. The results revealed that the content of hydrophilic group and the alkyl side chain length of the carboxylic acids played a crucial role in phase separation process, and the introduce of the benzyl group for quaternary ammonium salt had an aptitude to promote two-phase splitting. Then the system comprising [TBAB][Gly] and Na2SO4 was used to appraise the effect of different experimental parameters on the extraction efficiency, including the amount of DES and salt, the temperature, the values of pH and the ionic strength. More than 98% of lysozyme was transferred into the DES-rich phase at the optimum condition. The activity of lysozyme after the process of extraction still retained 91.73% of initial activity, demonstrating high biocompatibility of the studied system. What's more, the proposed method was successfully utilized for the real sample analysis. Finally, UV-vis, FT-IR, circular dichroism spectra, dynamic light scattering and transmission electron microscopy were employed to investigate the extraction mechanism. All of these results verify the excellent feasibility of the proposed system in the analysis of biological samples.

Ionic liquid modified molybdenum disulfide and reduced graphene oxide magnetic nanocomposite for the magnetic separation of dye from aqueous solution.

A novel ionic liquid (IL) modified magnetic nanocomposite (mag-MoS2-RGO), which was composed of molybdenum disulfide (MoS2) and reduced graphene oxide (RGO), was firstly synthesized and characterized (mag-MoS2-RGO-IL). Compared with mag-MoS2-RGO, the mag-MoS2-RGO-IL exhibited the higher adsorption capacity of 143.9 mg/g for methylene blue (MB) under optimum conditions. Experimental results were imitated by adsorption isotherms and kinetic models, revealing a monolayer adsorption on the homogeneous surface governed by chemisorption. The removal rate was maintained 78% after 5 cycles of regeneration, indicating its good reutilization. Methodological study suggested that the method possessed excellent repeatability, precision and stability. The recoveries from the real samples were in the range of 87.0-98.8% with relative standard deviation of ≤5.2%. Benefiting from composite structure and magnetic Fe3O4, the stable magnetic adsorbent can be quickly separated from aqueous solution. All of above proves that the prepared mag-MoS2-RGO-IL has great application potential in dye separation.

Poly(deep eutectic solvent)-functionalized magnetic metal-organic framework composites coupled with solid-phase extraction for the selective separation of cationic dyes.

Novel polymeric deep eutectic solvents (PDES) based on 3-acrylamidopropyl trimethylammonium chloride/D-sorbitol functionalized amino-magnetic (Fe3O4NH2) metal-organic framework (HKUST-1-MOF) composites (Fe3O4NH2@HKUST-1@PDES) were synthesized and characterized by field emission transmission electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM) and zeta potentials. Then the composites were firstly utilized to selectively separate malachite green (MG) and crystal violet (CV) coupled with magnetic solid-phase extraction (MSPE). A response surface methodology (RSM) based on Latin hypercube sampling (LHS) was selected to analytically optimize the extraction parameters including initial concentration of dyes, extraction time, pH value and extraction temperature. The maximum extraction amount and optimal extraction conditions predicted by the RSM model matched well with the actual experimental results, and the extraction amount was 966.93 mg g-1 for MG and 788.90 mg g-1 for CV,respectively. The results indicated that the model possessed higher calculation accuracy through analyzing fewer sample points, thereby achieving theoretical prediction of extraction amount and conditions and being a prefect supplementary to actual experiments. The electrostatic interaction between the composites and cationic dyes played the main roll in the extraction process. The proposed extraction method exhibited lower limit of detection (98.19 ng mL-1 for MG and 23.97 ng mL-1 for CV) and preeminent precision (RSD ˂ 0.4%). Spiked recoveries of fish samples at three spiking levers ranged from 89.43% to 100.65% for MG and 95.29%-98.03% for CV. All results highlighted the excellent potential of Fe3O4NH2@HKUST-1@PDES-MSPE strategy in selective separation of cationic dyes in complex medium.

Fabrication of magnetic polymers based on deep eutectic solvent for separation of bovine hemoglobin via molecular imprinting technology.

In this work, molecularly imprinted polymers (MIPs) were prepared with vinyl-coated magnetic particles (Fe3O4@VTEO) as the support material, deep eutectic solvent (DES) based on vinyl as the functional monomer, respectively. N,N-methylenebisacrylamide (MBAAm) was used as the crosslinker on account of its abundant carbon-carbon double bonds. The MIPs were prepared with the addition of bovine hemoglobin (BHb) acted as the template. The MIPs particles can be collected quickly by a magnetic field. The composition and morphology of the MIPs particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), fourier transform infrared spectrometry (FT-IR) and thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) was used to illustrate the cubic inverse spinel structure of Fe3O4. Meanwhile, vibrating sample magnetometer (VSM) was applied to characterize the magnetism of the MIPs. Adsorption experiments were performed to attain the optimum adsorption conditions. Under the optimized conditions, the obtained maximum adsorption capacity (Q, mg·g-1) of the MIPs particles is found to be 164.20 mg g-1, and the imprinting factor (IF) is 4.93. Four reference molecules were used to test the selectivity of the MIPs particles, which indicates that the recognition sites can adsorb template molecules with selectivity. Furthermore, the prepared magnetic MIPs particles were applied to capture BHb from the real samples (calf blood) effectively.

Development of different deep eutectic solvent aqueous biphasic systems for the separation of proteins.

In this work, aqueous biphasic systems (ABSs) formed by different deep eutectic solvents (DESs) were prepared and applied to extract proteins. The five kinds of DESs comprised amino acids and polyols ([amino acids][polyols]). They were combined with another DES resulting from tetrabutylammonium chloride and polypropylene glycol 400 ([TBAC][PPG400]) to form ABSs. The phase-forming abilities of [TBAC][PPG400]/[amino acids][polyols] were compared with those of [TBAC][PPG400]/amino acids and [TBAC][PPG400]/polyols. The results exhibited that the biphasic formation ability of [amino acids][polyols] lies between those of amino acids and polyols when [TBAC][PPG400] acts as the other phase in ABSs. The systems comprising [TBAC][PPG400] and [l-proline][xylitol] ([Pro][Xyl]) were further investigated to optimize the extraction performance. It was found that 97.30% chymotrypsin tended to distribute into the [Pro][Xyl]-rich phase under optimum conditions. The practical application of the system was demonstrated by the extraction of chymotrypsin from porcine pancreas. Besides, UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), and circular dichroism (CD) spectroscopy proved that the conformation of proteins remained unchanged during the extraction process. The extraction mechanism of the formation of DES-protein aggregates was investigated via conductivity, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The overall results suggest that the DES/DES-based ABSs have outstanding potential in the green extraction of proteins.

A novel aqueous biphasic system formed by deep eutectic solvent and ionic liquid for DNA partitioning.

In this work, aqueous biphasic systems (ABSs) composed of ionic liquids (ILs) and deep eutectic solvents (DESs) were developed and utilized to efficiently extract DNA for the first time. Four kinds of ILs/DESs were mainly constituted by betaine/carboxylic acid and betaine/carbohydrates respectively. While another DES ([TBAB][PPG400]) was formed by polypropylene glycol 400 (PPG 400) and tetrabutylammonium bromide (TBAB). The phase-formation ability of the studied ABSs was evaluated by using [TBAB][PPG400]/(ILs/DESs) and [TBAB][PPG400]/inorganic salts. The results revealed that the phase forming ability of ABSs involved with the size of anion alky chain of ILs, the viscosity, the density and the hydrophilicity of DESs, ionic radius and ionic valence of inorganic salts. Then the system comprising [TBAB][PPG400]/IL was selected to ascertain the optimum extraction conditions for the extraction of DNA by the influence factor experiments. Meanwhile the maximum extraction efficiency could be attained 99.60%. Mixed sample experiments were implemented to separate DNA/cytochrome C (Cyt-c) and DNA/bovine hemoglobin (BHb), where the DNA mainly partitioned to IL-rich bottom phase. It turned out that the relationship between the isoelectric point of analytes and the pH of the system played an important role in the separation process. The result also showed that the studied system can be applied to selectively separate mixtures of nucleic acids and proteins in a single-step. Moreover, the developed system was successfully applied to the extraction of DNA from bovine whole blood with satisfactory result. Finally, the extraction mechanisms associated with the separation process were explored by FT-IR spectra, circular dichroism spectra (CD), dynamic light scattering (DLS), transmission electron microscopy (TEM). Overall, the novel systems have been proven to be a remarkable performance in the separation of DNA, which is expected to be widely used and provide further possibilities in separation fields.

Magnetic solid-phase extraction for the removal of mercury from water with ternary hydrosulphonyl-based deep eutectic solvent modified magnetic graphene oxide.

A novel ternary hydrosulphonyl-based deep eutectic solvent (THS-DES) comprised of choline chloride/itaconic acid/3-mercaptopropionic acid (molar ratio 2:1:1) was firstly synthesized. The composition, property and microscopic structure of the new magnetic adsorbent (THS-DES@M-GO) based on the THS-DES modified the magnetic graphene oxide (M-GO) was characterized by the system. Magnetic solid-phase extraction (MSPE) based THS-DES@M-GO was firstly researched for the removal of mercury (Hg2+) from water. Various influencing factors such as the mass of adsorbent, solution pH, initial Hg2+ concentration, the removal time and temperature had been systematically tested. Under optimized conditions the removal efficiency (R%) could achieved 99.91%. The precision, repeatability and stability experiments were investigated in detail to evaluate the presented method. The relative standard deviations (RSD) of the removal efficiency were 0.053%, 1.49% and 1.55%, respectively. The maximum adsorption capacity (Qmax) was 215.1 mg g-1 and the data of the experiment fitted well with Langmuir model. Elution experimental studies shown that 94.94% of Hg2+ could be eluted by ethylenediaminetetraacetic acid (EDTA). After seven cycles of adsorption-desorption processes, the THS-DES@M-GO still retained a high removal efficiency of 90.23%. Compared with other adsorbents prepared in this work, THS-DES@M-GO displayed higher removal efficiency for Hg2+. Interference study proved the composites was tolerated and stabled under the complex matrix. What's more, the analysis of mercury contaminated water (from Guizhou, P.R., China) proved that the proposed method could be used to remove Hg2+ in practical application.

Creating magnetic ionic liquid-molecularly imprinted polymers for selective extraction of lysozyme.

A novel magnetic (Fe3O4) surface molecularly imprinted polymer (MIP) based on ionic liquid (IL) (Fe3O4@VTEO@IL-MIPs) was prepared for the selective extraction of lysozyme (Lys). As the functional monomer of the MIPs, an imidazolium-based IL with vinyl groups was prepared. It can provide multiple interactions with template molecules. The amount of IL was optimized (200 mg). Fourier transform infrared spectrometry (FT-IR), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA) and a vibrating sample magnetometer (VSM) were used to characterize the MIP. The results indicate the successful formation of an imprinting polymer layer. The concentration of Lys in the supernatant was determined by UV-vis spectrophotometry at a wavelength of 280 nm. The maximum adsorption capability of the MIP is 213.7 mg g-1 and the imprinting factor (IF) is 2.02. It took 2.5 h for the MIP to attain adsorption equilibrium. The structure of the protein was evaluated using circular dichroism (CD) spectra and UV-visible spectra. The adsorption performance was further investigated in detail by selective adsorption experiments, competitive rebinding tests, and reusability and stability experiments. Furthermore, it was utilized to separate the template protein from a mixture of proteins and real samples successfully because of the high adsorption capacity for Lys.