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Nanozymes have been widely developed as supplements of natural enzymes owing to their relatively low cost, high mass production, easy storage, good stability, and reusability. By controlling the particle size, nanozymes’ catalytic activities can distinctly be improved. The porous materials such as covalent organic frameworks (COFs) are definitely considered as promising supports for in situ preparation of high dispersity and small-size nanozymes. Herein, we designed and synthesized COF supported ultrafine platinum nanoparticles (Pt NPs/COF-300-AR) by controlling the growth of Pt NPs by using uniformly distributed nitrogen atoms of well-organized framework structures of 3D COFs. Pt NPs/COF-300-AR nanohybrids catalyzed the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) solution to turn blue, displaying excellent oxidase-like activity, good stability, and high reusability, which should be owed to the uniform size and high dispersity of ultrafine Pt NPs. By virtue of those advantages, the TMB-Pt NPs/COF-300-AR colorimetric platform was successfully applied to cellular glutathione detection. Similarly, other COFs with good acid resistance and abundant functional groups can also be used as the supports of a nanozyme, which will greatly expand the members of the nanoenzyme family. \ud KEYWORDS: oxidase mimic, in situ preparation, ultrafine Pt nanoparticles, COF support, glutathione, nanohybrids, colorimetry, cell lysate

The purpose of present study is to investigate the inhibitory effects of epicatechin (EC) on the formation of ALEs. A chemical model containing bovine serum albumin (BSA, 1 mg/mL) and fish oil (0.5 mg/mL) under accelerated metal-catalyzed oxidation (37 °C, 72 h) was established to mimic the generation of ALEs. The incorporation of EC (0.25, 0.5, 1, and 2 mmol/L) significantly reduced TBARS content in a dose-dependent manner (P

Perfluorooctane sulfonate (PFOS) is one of the perfluorinated compounds (PFCs), and has been used in industrial and consumer products. It has already been shown that PFOS could be detected in the environmental media and biological species including humans, due to its resistance to environmental degradation. PFOS is known to induce a series of adverse impacts on human health, e.g., as a potential neurotoxic substance. Recent studies suggest that astrocytes act as the mediator in PFOS-induced neurotoxicity; however, the underlying molecular mechanism needs further investigation. Under the physiological condition, astrocytes play an important role in maintaining brain functions through releasing and up-taking of neurotransmitters between astrocytes and neurons. In the present study, astrocytes-derived d -serine was shown to be involved in PFOS-induced apoptosis and death in the rat primary hippocampal neurons. Significant alterations in d -serine were found in astrocytes, mediated by the molecules in d -serine synthesis (serine racemase), metabolism ( d -amino acid oxidase) and delivery (calcium, vacuolar type H+-ATPase, alanine–serine–cysteine transporter and connexin 43 hemichannels). Meanwhile, the N-methyl- d -aspartate receptor (NMDAR) subunits (NR1, NR2 A and NR2B) gene and protein expressions were significantly increased in the hippocampal neurons exposed to the PFOS-activated astrocytes-conditional medium (ACM). Further, the adverse effects of PFOS could be attenuated by the fluorocitrate (an inhibitor for d -serine up-taken by the glial cells) application. Our data indicated that astrocytes-derived d -serine was involved in PFOS-induced neurotoxicity through the NMDARs in the rat primary hippocampal neurons.

Background The influence of epicatechin (EC) on the physicochemical properties and digestibility changes of porcine myofibrillar protein (MP) under oxidative stress during refrigerated storage was investigated. Results The incubation of MP suspensions (20 mg mL-1 in piperazine-N,N'-bis(2-ethanesulfonic acid) buffer, with 0.6 mol L-1 sodium chloride, pH 6.25) at 4 °C for 24 h under an iron-catalyzed hydroxyl radical generating system (Fenton reaction) promoted the formation of thiobarbituric acid reactive substances and protein carbonyls, which was attenuated by EC (5, 50, and 100 μmol g-1 protein). Reduced protein sulfhydryl content, tryptophan fluorescence, protein solubility, as well as increased surface hydrophobicity were found by the co-incubation of EC. Analysis by scanning electron microscopy revealed increased protein aggregation and fragments in oxidized MP, which were further enhanced by the addition of EC. However, the protein digestibility of MP was not affected. Conclusion EC was demonstrated to be effective in alleviating lipid oxidation and protein carbonylation in MP under oxidative stress. Additionally, the physicochemical and digestibility changes accompanying the incorporation of EC was complicated due to the possible phenol-protein interactions. An in-depth understanding of protein physicochemical and digestibility changes will be helpful in the application of polyphenolic compounds as antioxidants in low-temperature-processed muscle foods. © 2020 Society of Chemical Industry.

Levodopa (L-DOPA) is promising as chiral stationary phase for open tubular capillary electrochromatography (OT-CEC) enantioseparation owing to its self-polymerization adhesive property and chiral recognition potential. In this work, CuSO4/H2O2 was used as a trigger agent to accelerate the polymerization process of L-DOPA and the poly-levodopa (poly-(L-DOPA)) coated column was successfully prepared for the first time by depositing it on the inner wall of fused silica capillary via the rapid and in-situ approach at room temperature. The performance of the poly-(L-DOPA) coated capillary was validated by the separation of different chiral analytes, including chiral amine drugs, neurotransmitters and amino acids, and the good enantioseparation efficiencies were achieved. For five consecutive runs, the relative standard deviations (RSDs) for the migration time of the analytes for intra-day, inter-day and column-to-column were in the range of 0.19-1.33%, 0.96-4.47%, and 2.21-7.79%, respectively. Additionally, the poly-(L-DOPA) coated capillary column could be successively used over 250 runs without observable change in the separation efficiency.

An ingenious and viable method for preparing heterogeneous Co3O4 dodecahedrons that contain carbon and encapsulated Au nanoparticles (Au@C-Co3O4) was proposed via pyrolysis of Au nanoparticle-encapsulated zeolitic imidazolate framework-67 (Au@ZIF-67). The obtained Au@C-Co3O4 possessed hierarchically porous structure, abundant active sites, excellent conductivity, and durability, all of which can significantly improve the analysis performance of the biosensor. Meanwhile, the fabricated electrode based on the porous Au@C-Co3O4 showed remarkable electrocatalytic performance towards H2O2 with a limit of detection of 19 nM and ultra-high sensitivity of 7553 μA mM−1 cm−2, even when the Au content in the composite was as low as 0.85 wt%. This novel biosensor was successfully used to monitor H2O2 concentration released from living cells, and the results can be used to identify cancer cells, thus advancing the use of transition metal oxides in the field of biosensing.

Silicon nanoparticles (SiNPs) have attracted increasing attentions due to their unique properties and related applications. However, previously reported SiNPs generally showed emission band only in the blue- or green-light regions, which limited their applications in biochemical samples. So far, synthesis of longer wavelength emissive SiNPs remains a challenge. In this paper, the yellow-emitting fluorescent SiNPs were prepared via a facile room temperature procedure, which avoided heating and pressurizing operation, multistep and time-consuming post-modified procedures. The obtained SiNPs displayed excellent water-solubility, pH-stability, salt-tolerance, and photo-stability. Significantly, the fluorescence of SiNPs could be remarkably quenched by crystal violet (CV) via synergistic effect of inner filter effect (IFE) and fluorescence resonance energy transfer (FRET). Based on this phenomenon, a method for the determination of CV was established. Under the optimum conditions, the method showed a wide linearity range from 0.075 to 15.0 μg/mL with a limit of detection of 25 ng/mL. Furthermore, the method was successfully applied to the analysis of CV in fish tissues samples.

In this work, CoFe2O4 nanoparticles coated with polyethylene glycol (PEG) were successfully synthesized via a hydrothermal technique. Morphological studies of the samples confirmed the formation of polycrystalline pure-phase PEG-CoFe2O4 nanoparticles with sizes of about 24 nm. Toxicity induced by CoFe2O4 nanoparticles was investigated, and biological assays were performed to check the toxicity effects of CoFe2O4 nanoparticles. Moreover, the healing effect of toxicity induced in living organisms was studied using curcumin and it was found that biochemical indexes detoxified and improved to reach its normal level after curcumin administration. Thus, PEG-coated CoFe2O4 synthesized through a hydrothermal method can be utilized in biomedical applications and curcumin, which is a natural chemical with no side effects, can be used for the treatment of toxicity induced by the nanoparticles in living organisms.

A novel ternary transition metal oxide (TTMO) FeMnO3 microcube with an average diameter of about 1.0 μm was successfully fabricated via the pyrolysis of Mn-Fe Prussian blue analogue (PBA) at 650 °C. As an anode material for lithium ion batteries (LIBs), it showed a steady reversible capacity of 710 mAh g−1 at a high current density of 1 A g−1 after 200 cycles with 80% retention. The remarkable electrochemical storage properties are attributed to the microcubic structure inherited from the precursor and structure stability, which can effectively buffer the volume expansion during the discharge-charge process. Its excellent features, such as low cost, environmentally friendliness, simple preparation and outstanding electrochemical properties, make the obtained FeMnO3 a promising electrode material for electrochemical storage devices.

In this work, we report a durable and sensitive H2O2 biosensor based on boronic acid functionalized metal-organic frameworks (denoted as MIL-100(Cr)-B) as an efficient immobilization matrix of horseradish peroxidase (HRP). MIL-100(Cr)-B features a hierarchical porous structure, extremely high surface area, and sufficient recognition sites, which can significantly increase HRP loading and prevent them from leakage and deactivation. The H2O2 biosensor can be easily achieved without any complex processing. Meanwhile, the immobilized HRP exhibited enhanced stability and remarkable catalytic activity towards H2O2 reduction. Under optimal conditions, the biosensor showed a fast response time (less than 4s) to H2O2 in a wide linear range of 0.5-3000μM with a low detection limit of 0.1μM, as well as good anti-interference ability and long-term storage stability. These excellent performances substantially enable the proposed biosensor to be used for the real-time detection of H2O2 released from living cells with satisfactory results, thus showing the potential application in the study of H2O2-involved dynamic pathological and physiological process.

Heteroatom-doped carbon nanoparticles (CNPs) have attracted considerable attention due to an effective improvement in their intrinsic properties. Here, a facile and simple synthesis of nitrogen, boron co-doped carbon nanoparticles (NB-CNPs) from a sole precursor, 3-aminophenylboronic acid, was performed via a one-step solid-phase approach. Because of the presence of boronic acid, NB-CNPs can be used directly as a fluorescent probe for glucose. Based on a boronic acid-triggered specific reaction, we developed a simple NB-CNP probe without surface modification for the detection of glucose. When glucose was introduced, the fluorescence of NB-CNPs was suppressed through a surface-quenching states mechanism. Obvious fluorescence quenching allowed the highly sensitive determination of glucose with a limit of detection of 1.8 μM. Moreover, the proposed method has been successfully used to detect glucose in urine from people with diabetes, suggesting potential application in sensing glucose.

In this work, molybdenum disulfide quantum dots (MOS2 QDs) were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors, and applied in ascorbic acid detection. When joining MnO2 nanosheets into MOS2 QDs solution, they produced an obvious fluorescence quenching, which should be due to inner filter effect (IFE). Meanwhile, the fluorescent probe was formed. Interestingly, we found that this quenching phenomenon disappeared with the addition of ascorbic acid. In other words, the fluorescence gradually restored. This recovery phenomenon is mainly due to the reduction effect of ascorbic acid for MnO2 nanosheets. Under the optimum conditions, the limit of detection (LOD) of 39 nmol/L for ascorbic acid was achieved with a linear range of 0.33-5.00 mu mol/L. The repeatability was better than 5.0% for ascorbic acid in both standard and fruit samples (n=3). Moreover, the as-fabricated fluorescent sensing system was successfully employed to detect the ascorbic acid levels in hawthorn and jujube with satisfactory results. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Developing simple methods for separation of analytes that belong to different classes is of great importance. Herein, we developed a simple one-dimensional (1-D) capillary electrochromatography method to demonstrate the simultaneous separation of target fractions that belong to two different classes (i.e., cationic and neutral analytes) without switching buffer solution by a zeolitic imidazolate framework ZIF-8 coated capillary column. Owing to the difference of charge-to-mass ratio of the cationic analytes, the interaction of the cationic analytes and coating material ZIF-8 and the hydrophobic interactions between the neutral analytes and the microporous framework of ZIF-8, six cationic analytes and four neutral analytes were simultaneously separated in a single run by 1-D capillary electrochromatography. The relative standard deviations (RSDs) of the analytes migration time for intra-day, inter-day and column-to-column were in the range of 0.11-0.87%, 0.54-2.04% and 2.00-6.89% and the RSDs of the analytes peak area for intra-day, inter-day and column-to-column were in the range of 0.70-4.45%, 1.33-6.20% and 2.27-11.88%. Additionally, the developed method was employed in the analysis of urine samples with satisfactory recoveries.

Two-dimensional (2D) COFs have been successfully applied for various applications, such as capillary electrochromatography (CEC). Compared with 2D COFs, three-dimensional (3D) COFs have higher surface area and lower density, which should have superior potential as the separation medium in CEC. However, the 3D COFs on the inner wall of capillary is hard to fabricate in situ. Up to date, the application of 3D COFs in open-tubular capillary electrochromatography (OT-CEC) is still considered a challenge. For the first time the COF-300-coated capillary was prepared by in situ growth (COF-300 was made from terephthalaldehyde and tetra-(4-anilyl)-methane) on OT-CEC. Benzene, methylbenzene, styrene, ethylbenzene, naphthalene, 1-methylnaphthalene, and propylbenzene were used to evaluate the performance of the COF-300-coated capillary by OT-CEC. For three consecutive runs, the intraday relative standard deviations (RSDs) of migration time and peak areas were 0.1-0.4% and 2.5-8.3%, respectively. The interday RSDs of migration time and peak areas were 0.2-0.5% and 1.0-10.8%, respectively. Five groups of aromatic co mpounds were used to further study the separation mechanism, which indicated that hydrophobic interaction and size selection interaction are the main factors. It should be noted that the COF-300-coated capillary can be used for more than 140 runs with no observable changes of the separation efficiency. Graphical abstract The 3D COF-300-coated capillary was prepared by in situ growth for OT-CEC. Six groups of aromatic compounds were separated by 3D COF-300-coated capillary. Size selection and hydrophobic interaction affect the migration time of analytes.

Impacts of lipid oxidation product malondialdehyde (MDA) on the properties of whey protein isolate (WPI) were investigated in this study. The incorporation of MDA into WPI promoted the formation of protein carbonyls, with the significant loss of protein sulfhydryls, impaired intrinsic fluorescence, and increased protein surface hydrophobicity. The visualized band profiles revealed by gel electrophoresis and immunoblotting suggested that WPI's main components β-lactoglobulin and α-lactalbumin were the targets of MDA, and the derivatives of MDA were involved in protein cross-linking and aggregation at higher molecular weights. Abnormal protein aggregation was further confirmed by scanning electron microscopy analysis of the surface microstructure of MDA-modified WPI. Finally, in vitro digestibility assay indicated that the modification of MDA reduced WPI's susceptibility to digestive enzymes. The present study demonstrated that the contribution of MDA to protein modification in dairy products can be substantial in complex foodstuffs composed of lipids and proteins. PRACTICAL APPLICATIONS: The present work enhanced our knowledge on the remarkable susceptibility of dairy product WPI to lipid oxidation product MDA. With the trend of application of highly unsaturated fatty acids such as fish oil or alga oils as functional ingredients in dairy products, it is obvious that apart from monitoring lipid oxidation products, the resultant changes in dietary proteins deserve more attention. The food industry must be aware of the importance of appropriate preventive measures in minimizing the negative effects of lipid oxidation products on dairy products.

Here we demonstrate the seed-mediated growth approach, one of the most reliable and versatile methods to control the size and shape of nanocrystals (NCs), for rapid synthesis of high performance red-emitting core/shell CdTe quantum dots (QDs) in aqueous phase. Critical parameters (including the pH value, Cd:Te molar ratio, MPA:Cd molar ratio, and the amount of CdTe seeds) affecting the growth of core/shell CdTe QDs are systematically introduced and analyzed. Under optimal conditions, the growth behaviors can be well controlled, and the high performance typically offered by the seed-mediated growth method was obtained as expected. The emission peak position quickly shifted from 540 to 680 nm in 30 min, and the red-emitting CdTe QDs thus obtained performed well, giving good size distribution, narrow full width at half maximum and high quantum yield. The growth mechanism and the resulting high structural and optical properties were also elucidated. Finally, the obtained CdTe QDs were successfully applied to highly reactive oxygen species (hROS) sensing, suggesting that this method may be useful in bioimaging and biolabeling.

Taurine is an important amino acid for the growth and development of the central nervous system and plays an important role in the development of the nervous system. Many studies have shown that taurine can prevent and repair neurodevelopmental damage, and its mechanism has also become a research hotspot. While most studies focus on nerve cells, less on placental cells that are closely related to early neurodevelopment (developmental neurotoxicity) by modulating fetal circulation level of thyroid hormones. Studies have shown that exposure of placental cells to the common environmental endocrine disruptor BDE 209 during early pregnancy may lead to developmental neurotoxicity due to thyroid hormone interference caused by abnormal expression of deiodinases. Therefore, in this study, the placenta-derived JEG cells cultured at 95% air/5% CO2 was used as a in vitro model, and the potential protection from taurine on BDE 209-mediated cytotoxicity was examined. When BDE 209 was found to cause a decrease in cell viability and disturbance in the gene and protein expressions of placental deiodinase 3, pretreatment of the JEG cells with taurine can moderately reduce the BDE 209-meditated cytotoxicity, and restore gene and protein expressions of placental deiodinase, so that thyroid hormone levels tend to be normal in cell culture medium. Our data suggest that taurine may have some protection on the developmental neurotoxicity caused by BDE 209.

PBDEs (stands for polybrominated diphenyl ethers) are extensively utilized flame retardants, and BDE 209 is one of the most widely used congeners. Studies have suggested the general toxic effects of PBDEs on the endocrine system and neural development. Our previous studies found that BDE 209 changed Type 3 iodothyronine deiodinase (Dio 3) expression in human SK-N-AS neuroblastoma cells. The current study was designed to examine the potential protection of taurine on alterations of Dio 3 expression induced by BDE 209 in SK-N-AS cells. Briefly, SK-N-AS cells were pretreated with taurine prior to the BDE 209 treatment, and the cell viability was evaluated by the MTT (methyl-thiazolyl-tetrazolium) assay. The disturbance or restoration in the levels of Dio 3 proteins and mRNA were observed separately by the western blot and qRT-PCR. Our data showed that taurine moderately attenuated BDE 209-mediated the loss of cell viability. Also, taurine moderately prevented the reduction in the Dio 3 protein expression and mRNA expression induced by BDE 209 in the SK-N-AS cells. Our findings indicated that taurine potentially provide the protection on PBDEs-induced toxicity on endocrine and neuro-development.

In recent years, covalent organic frameworks (COFs) play an important role in the field of chromatographic separation. However, COFs are used rarely in open-tubular capillary electrochromatography (OT-CEC) so far, and the reported methods have not been applied to actual sample analysis. Herein, a novel azine-linked COF (N0-COF) coated capillary was prepared as OT-CEC separation channel and a new method for separation and detection of environmental endocrine disruptors, i.e., bisphenol A (BPA) and its analogues was established. Under optimal separation conditions, the analytes were baseline separated by the N0-COF coated capillary with 20 min. The intra-day, inter-day and column-to-column relative standard deviations were 0.07–2.99%, 1.05–3.20% and 1.31–5.83% for the migration time; 1.68–5.50%, 1.52–9.24% and 4.04–9.14% for the peak area. The method was further applied to separate and determine BPA and its analogues in beverage samples, and the recovery ranged from 91.0–112.0%.

Exploration of the simple and stable coating methods is of great significance in capillary electrochromatography (CEC). In this work, a lysozyme assemble supramolecular membrane coated capillary column was developed for CEC chiral separation. Taking advantage of phase transformation of lysozyme, the coating process was achieved within 1.0 h thus to a large extent reduced the capillary preparation time and simplified the coating procedure. The successful fabrication of the supramolecular membrane coated capillary was verified by scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), fluorescence imaging, and electroosmotic flow (EOF). The separation capacity of the coated capillary was evaluated by analysis of different chiral analytes, including chiral amine drug and neurotransmitters, and good enantioseparation efficiency was achieved for the three pairs of enantiomers. For three consecutive runs, the relative standard deviations (RSD) for the migration time of the analytes for intra-day (n = 3), inter-day (n = 3) and column-to-column (n = 3) were in the range of 0.7–1.5%, 2.7–3.6%, and 4.5–5.8%, respectively. Additionally, the supramolecular membrane coated capillary column could run consecutively 100 times without observable change in the separation efficiency, proving the feasibility of the coating method based on the adhesion of the protein-based supramolecular membrane.

A good understanding of the mechanism of interaction between quantum dots (QDs) and heavy metal ions is essential for the design of more effective sensor systems. In this work, CE was introduced to explore how l-cysteine-capped-CdTe QDs (l-cys-CdTe QDs) interacts with Hg(2+) . The change in electrophoretic mobility can synchronously reflect the change in the composition and property of QDs. The effects of the free and capping ligands on the system are discussed in detail. ESI-MS, dynamic light scattering (DLS), zeta potential, and fluorescence (FL) were also applied as cooperative tools to study the interaction mechanism. Furthermore, the interaction mechanism, which principally depended on the concentration of Hg(2+) , was proposed reasonably. At the low concentration of Hg(2+) , the formation of a static complex between Hg(2+) and the carboxyl and amino groups of l-cys-CdTe QDs surface was responsible for the FL quenching. With the increase of Hg(2+) concentration, the capping l-cys was stripped from the surface of l-cys-CdTe QDs due to the high affinity of Hg(2+) to the thiol group of l-cys. Our study demonstrates that CE can reveal the mechanism of the interaction between QDs and heavy metal ions, such as FL quenching.

Fluorescence sensing of specific biological molecules by artificial chemosensors is a versatile technique. In the present work, a switch-on fluorescence sensor for rapid, sensitive, and selective sensing of glutathione (GSH) in food samples was developed. This method was based on the g-CNQDs–Hg2+ system, in which the initial fluorescence from g-CNQDs was quenched by Hg2+ with an electron transfer process. In the presence of GSH, the fluorescence sensor was switched to the “on” state, which was attributed to a competitive affinity of Hg2+ to GSH and the functional groups on the surface of g-CNQDs. Under the optimal conditions, the limit of detection (LOD) of 37 nM for GSH was achieved with a wide range of 0.16–16 μM. The repeatability was better than 5.3% for GSH in both standard and food samples (n = 3). Finally, this fluorescence sensor was successfully employed for the determination of GSH in various kinds of food samples with excellent recoveries. Furthermore, this application may pave a new way for fl...

In recent years, artificial materials with double helix structure have attracted widespread attention due to their unique properties such as the DNA like double-helicity, intrinsic chirality and diverse functional groups. Developing novel chiral stationary phases (CSPs) for capillary electrochromatography enantioseparation is of intriguing interest. Herein, a novel homochiral zeolite-like metal-organic framework (ZMOF) JLU-Liu23 with unique DNA like double-helicity structure was firstly utilized as the CSP in open tubular capillary electrochromatography (OT-CEC) for enantioseparation of chiral monoamine neurotransmitters and analogues. Owing to the unique DNA like double-helicity structure of the homochiral ZMOF JLU-Liu23, the good enantioseparation of four monoamine neurotransmitters and analogues was achieved on the prepared homochiral ZMOF JLU-Liu23 coated capillary column. The relative standard deviations (RSDs) of the analytes migration time for intra-day, inter-day and column-to-column were in the range of 0.3-0.6%, 0.8-2.2% and 3.5-6.5%, respectively.

The popularity of novel nanoparticles coated capillary column has aroused widespread attention of researchers. Metal organic frameworks (MOFs) with special structure and chemical properties have received great interest in separation sciences. This work presents the investigation of HKUST-1 (Hong Kong University of Science and Technology-1, called Cu3(BTC)2 or MOF-199) nanoparticles as a new type of coating material for capillary electrochromatography. For the first time, three layers coating (3-LC), five layers coating (5-LC), ten layers coating (10-LC), fifteen layers coating (15-LC), twenty layers coating(20-LC) and twenty-five layers coating (25-LC) capillary columns coated with HKUST-1 nanoparticles were synthesized by covalent bond with in situ, layer-by-layer self-assembly approach. The results of scanning electron microscopy (SEM), X-ray diffraction (XRD) and plasma atomic emission spectrometry (ICP-AES) indicated that HKUST-1 was successfully grafted on the inner wall of the capillary. The separating performances of 3-LC, 5-LC, 10-LC, 15-LC, 20-LC and 25-LC open tubular (OT) capillary columns were studied with some neutral small organic molecules. The results indicated that the neutral small organic molecules were separated successfully with 10-LC, 15-LC and 20-LC OT capillary columns because of the size selectivity of lattice aperture and hydrophobicity of organic ligands. In addition, 10-LC and 15-LC OT capillary columns showed better performance for the separation of certain phenolic compounds. Furthermore, 10-LC, 15-LC and 20-LC OT capillary columns exhibited good intra-day repeatability with the relative standard deviations (RSDs; %) of migration time and peak areas lying in the range of 0.3-1.2% and 0.5-4.2%, respectively. For inter-day reproducibility, the RSDs of the three OT capillary columns were found to be lying in the range of 0.3-5.5% and 0.3-4.5% for migration time and peak area, respectively. The RSDs of retention times for column-to-column for three batches of 10-LC, 15-LC and 20-LC OT capillary columns were in the range from 2.3% to 7.2%. Moreover, the fabricated 10-LC, 15-LC and 20-LC OT capillary columns exhibited good repeatability and stability for separation, which could be used successively for more than 120 runs with no observable changes on the separation efficiency.

Inspired by the chiral recognition ability of β-cyclodextrin and the natural adhesive properties of polydopamine under alkaline conditions, in this study, a rapid and in situ modification strategy was developed to fabricate β-cyclodextrin/polydopamine composite material coated-capillary columns for open tubular capillary electrochromatography. The results of scanning electron microscopy, FTIR spectroscopy, streaming potential and electro-osmotic flow studies indicated that β-cyclodextrin/polydopamine was successfully fixed on the inner wall of the capillary column. This coating can be achieved within 1 h affording a greatly reduced capillary preparation time. The performance of the β-cyclodextrin/polydopamine-coated capillary was validated by the analysis of seven pairs of chiral analytes, namely epinephrine, norepinephrine, isoprenaline, terbutaline, verapamil, tryptophane, carvedilol. Good enantioseparation efficiencies were achieved for all. For three consecutive runs, the relative standard deviations for the migration times of the analytes for intra-day, inter-day and column-to-column repeatability were in the range of 0.41–1.74%, 1.03–4.18%, and 1.66–8.24%, respectively. Moreover, the separation efficiency of the β-cyclodextrin/polydopamine-coated capillary column did not decrease obviously over 90 runs. The strategy should also be feasible to introduce and immobilize other chiral selectors on the inner walls surface of capillary columns. This article is protected by copyright. All rights reserved

In this study, cobalt doped magnetic composite nanoparticles (Co x Fe 3− x O 4 MNPs) were firstly prepared through a simple and convenient coprecipitation approach. The characterization results from EDX, ICP-AES, TEM, XRD and XPS showed that the cobalt atoms might be located in the lattice position instead of the part of iron atoms. Co x Fe 3− x O 4 MNPs possessed higher peroxidase-like activity comparing with Fe 3 O 4 MNPs, although they were similar in crystal structure, size distribution and morphology. The as-prepared nanomaterials could effectively catalyze the reaction between 3,3,5,5-tetramethylbenzidine (TMB) and H 2 O 2 under 40 °C within 15 min. Dopamine (DA) has some reducibility due to the existence of phenol hydroxyl group, which results in it can consume H 2 O 2 and cause the blue shallowing of the reaction solution between H 2 O 2 and TMB. A visual, sensitive and simple colorimetric method based on Co x Fe 3− x O 4 MNPs as peroxidase mimetics was developed for detecting DA. Good linear relationship and recoveries for DA were obtained from 0.6 to 8.0 μM and 98.7 to 101.0%, respectively. The limit of detection (LOD) of the proposed method was calculated as 0.13 μM. And the relative standard deviation (RSD) was less than 4.0%. The visual method was successfully applied to DA detection in Common Yam Rhizome (Shan Yao) and human serum sample.

A novel coated capillary was prepared by immobilizing graphene oxide (GO) on the fused-silica capillary (75 μm i.d.) which was derivatized by 3-aminopropyl-trimethoxysilane (APTMS). The bare capillary, APTMS modified capillary (NH2-capillary) and GO coated capillary (GO-capillary) were characterized by streaming potentials (SPs), fluorescence microscope and scanning electron microscope (SEM). The results indicated that the capillary was successfully modified with GO sheets via covalent bonding and electrostatic effect. Compared with bare capillary, greater separation efficiency was achieved by GO-capillary column as a result of the increasing interactions between the small organic molecules and the inner wall of the GO-capillary column originated from the π-π electrostatic stacking. For three consecutive runs, the intra-day relative standard deviations (RSDs) of migration time and peak areas were 0.6-4.3% and 2.8-9.3%, respectively. The inter-day relative standard deviations of migration time and peak areas were 0.2-8.3% and 4.5-9.6%. Additionally, one GO-capillary column could be used for more than 100 runs with no observable changes on the separation efficiency.

The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation, fast response, and non-destructiveness. We investigated the potential of NIR spectroscopy in diffuse reflectance mode for determining the soluble solid content (SSC) and acidity (pH) of intact loquats. Two cultivars of loquats (Dahongpao and Jiajiaozhong) harvested from two orchards (Tangxi and Chun'an, Zhejiang, China) were used for the measurement of NIR spectra between 800 and 2500 nm. A total of 400 loquats (100 samples of each cultivar from each orchard) were used in this study. Relationships between NIR spectra and SSC and acidity of loquats were evaluated using partial least square (PLS) method. Spectra preprocessing options included the first and second derivatives, multiple scatter correction (MSC), and the standard normal variate (SNV). Three separate spectral windows identified as full NIR (800approximately2500 nm), short NIR (800approximately1100 nm), and long NIR (1100approximately2500 nm) were studied in factorial combination with the preprocessing options. The models gave relatively good predictions of the SSC of loquats, with root mean square error of prediction (RMSEP) values of 1.21, 1.00, 0.965, and 1.16 degrees Brix for Tangxi-Dahongpao, Tangxi-Jiajiaozhong, Chun'an-Dahongpao, and Chun'an-Jiajiaozhong, respectively. The acidity prediction was not satisfactory, with the RMSEP of 0.382, 0.194, 0.388, and 0.361 for the above four loquats, respectively. The results indicate that NIR diffuse reflectance spectroscopy can be used to predict the SSC and acidity of loquat fruit.

The feasibility of rapid analysis for oligosaccharides, including isomaltose, isomaltotriose, maltose, and panose, in Chinese rice wine by Fourier transform near-infrared (FT-NIR) spectroscopy together with partial least-squares regression (PLSR) was studied in this work. Forty samples of five brewing years (1996, 1998, 2001, 2003, and 2005) were analyzed by NIR transmission spectroscopy with seven optical path lengths (0.5, 1, 1.5, 2, 2.5, 3, and 5 mm) between 800 and 2500 nm. Calibration models were established by PLSR with full cross-validation and using high-performance anion-exchange chromatography coupled with pulsed amperometric detection as a reference method. The optimal models were obtained through wavelength selection, in which the correlation coefficients of calibration (r(cal)) for the four sugars were 0.911, 0.938, 0.925, and 0.966, and the root-mean-square errors of calibrations were 0.157, 0.147, 0.358, and 0.355 g/L, respectively. The validation accuracy of the four models, with correlation coefficients of cross-validation (r(cv)) being 0.718, 0.793, 0.681, and 0.873, were not very satisfactory. This might be due to the low concentrations of the four sugars in Chinese rice wine and the influence of some components having structures similar to those of the four sugars. The results obtained in this study indicated that the NIR spectroscopy technique offers screening capability for isomaltose, isomaltotriose, maltose, and panose in Chinese rice wine. Further studies with a larger Chinese rice wine sample should be done to improve the specificity, prediction accuracy, and robustness of the models.

The potential of near-infrared (NIR) transmittance spectroscopy to nondestructively detect soluble solids content (SSC) and pH in tomato juices was investigated. A total of 200 tomato juice samples were used for NIR spectroscopy analysis at 800–2400 nm using an FT-NIR spectrometer. Multiplicative signal correction (MSC), and the first and second derivative were applied for pre-processing spectral data. The relationship between SSC, pH, and FT-NIR spectra of tomato juice were analyzed via partial least-squares (PLS) regression. PLS regression models were able to predict SSC and pH in tomato juices. The rc, RMSEC, RMSEP, and RMSECV for SSC were 0.92, 0.0703°Brix, 0.150°Brix, and 0.138°Brix, respectively, whereas those values for pH were 0.90, 0.0333, 0.0316, and 0.0489, respectively. It is concluded that the combination of NIR transmittance spectroscopy and PLS methods can be used to provide a technique of convenient, versatile, and rapid analysis for SSC and pH in tomato juices.

Li4Ti5O12 is an important type of anode material for rechargeable Li battery due to its excellent cycling and thermal reliability, but the poor conductivity represents a significant challenge in the scalable application. Here we design a ternary Li4Ti5O12/TiO2@CNT core/shell structure to well mitigate the conductivity issue. The hybrid core/shell structure is fabricated by a facile hydrothermal reaction followed by heat treatment at 600 degrees C. It is comprised of Li4Ti5O12/TiO2 nanocrystals several nanometers in dimension tightly anchored on CNT network. The CNT network provides a fast and robust conductive way for electron transport, while the minor rutile-TiO2 phase improves the kinetics of Li4Ti5O12 toward fast lithium insertion/extraction. The electrochemical results indicate that the core/shell structure displays a high electrochemical activity in terms of reversible capacity and rate capability. The hybrid structure also shows excellent long-term cycling stability when operated at a high rate of 5 C.

Covalent organic frameworks (COFs) have attracted much attention because of their permanent nanoscale porosity and higher surface area compared to zeolites as well as robustness. COFs have great potential in several fields such as hydrogen storage, gas separation, and catalysis. However, COFs have not yet been applied in capillary electrochromatography. Herein, covalent organic frameworks-LZU1 (COF-LZU1) was used as the stationary phase in open-tubular capillary electrochromatography for the first time. Compared to the monoliths used in electrochromatography, the preparation technique of a COF-LZU1-coated capillary was simple and practical. The baseline separation of model analytes including alkylbenzenes, polyaromatic hydrocarbons, and anilines by the COF-LZU1-coated capillary was achieved based on the size selectivity of COF-LZU1 porous structure and hydrophobic interactions between the model analytes and organic ligands of COF-LZU1. The load capacity of the COF-LZU1-coated capillary for naphthalene was 0.6mg/mL. For three consecutive runs, the intraday relative standard deviations (RSDs) were 1.4-2.6% for the migration time and 2.7-8.7% for the peak area. The interday RSDs were 1.3-3.9% for the migration time and 3.7-9.7% for the peak area. The column-to-column reproducibility of migration time was in the range 1.0-3.9%. Moreover, the coated capillary was used for >300 runs with no changes in the separation efficiency. Thus, COFs have great potential in capillary electrochromatography and may provide a new method for chromatographic separation.

A novel and effective ratiometric fluorescence strategy was developed for rapidly, sensitively and selectively probing sulfide anions (S(2-)). A dual-emission nanosensor was prepared by covalently attaching fluorescent carbon nanoparticles (CNPs) to gold nanoclusters (Au NCs), triggering the sensing mechanism of fluorescence resonance energy transfer (FRET) from CNPs (donor) to Au NCs (acceptor). Once S(2-) was added, considerable fluorescence recovery of CNPs and quenching of Au NCs were observed due to the inhibition of FRET progress via the formation of Au2S. The ratiometric probe showed good, specific S(2-) sensing behavior and high sensitivity with a detection limit of 18 nM. Significantly, the assay was successfully employed to determine the S(2-) content in biological and water samples, presenting immense promise in the biological and environmental fields.

The feasibility of rapid analysis of glucose and fructose in lotus root powder by Fourier transform near-infrared (FT-NIR) spectroscopy was studied. Diffuse reflectance spectra were collected between 4000 and 12,432cm(-1). Calibration models established by partial least-squares regression (PLSR), interval PLS of forward (FiPLS) and backward (BiPLS), back propagation-artificial neural networks (BP-ANN) and least squares-support vector machine (LS-SVM) were compared. The optimal models for glucose and fructose were obtained by LS-SVM with the first 10 latent variables (LVs) as input. For fructose the correlation coefficients of calibration (rc) and prediction (rp), the root-mean-square errors of calibration (RMSEC) and prediction (RMSEP), and the residual predictive deviation (RPD) were 0.9827, 0.9765, 0.107%, 0.115% and 4.599, respectively. For glucose the indexes were 0.9243, 0.8286, 0.543%, 0.812% and 1.785. The results indicate that NIR spectroscopy technique with LS-SVM offers effective quantitative capability for glucose and fructose in lotus root powder.

The feasibility of visible and near-infrared (Vis-NIR) spectroscopy together with least-squares support vector machines (LS-SVM) for non-destructive determination of rice wine composition in coloured bottles was investigated. The Vis-NIR spectra were collected in a fiber spectrometer system with the bottle sealed and the labels removed. Statistical equations were established between the reference data and Vis-NIR spectra by partial least squares regression (PLSR) and LS-SVM, respectively. The prediction performance of LV-SVM is superior to that of PLSR, with higher rval of 0.960, 0.942 and 0.866, and lower RMSEP of 0.115 % (V V-1), 0.071 g L-1 and 0.021 for alcohol content, titratable acidity and pH, respectively. Based on the results, it was concluded that the Vis-NIR spectrometer system was suitable for non-destructive rice wine quality determination, and LS-SVM was a reliable multivariate method for rice wine composition prediction.

Optical path length is one of the most important factors in Beer-Lambert Law which is the basis of nearly all multivariate calibration methods for spectroscopic data. The effect of optical path length on the near infrared (NIR) spectra of rice wine and the consequences on the prediction precision of calibration models developed for measuring total sugar, non-sugar solid, alcohol content, titratable acidity, amino acid nitrogen, and pH was investigated. Samples were scanned in transmission mode using a commercial FT-NIR spectrometer and a demountable liquid cell for versatile path length liquid sampling. Eleven optical path lengths were studied: 0.5 mm, 0.75 mm, 1.0 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2.0 mm, 2.25 mm, 2.5 mm, 2.75 mm, and 3.0 mm. The NIR spectra of rice wine samples in different optical path length show that increasing the optical path length raised the absorption intensity but shortened the wavelength range in which absorbance measurement could be made. And, a linear relationship was observed between the absorption intensity and the optical path length when absorption intensity was lower than 3.0. It could also be observed that optical path length did have influence on the calibration results for the six enological parameters, and the recommended optical path length for total sugar, non-sugar solid alcohol content, titratable acidity, amino acid nitrogen and pH was 0.75 mm, 1 mm, 2 mm, 1.75 mm, 0.5 mm and 2 mm, respectively. The results demonstrated that it was necessary to determine the optimum optical path length to obtain the optimum results for NIR analysis.

Near-infrared (NIR) transmittance spectroscopy combined with several chemometrical techniques was investigated to study the oxidation process during storage in tomato juices. A total of 100 tomato juice samples were used for NIR spectroscopy analysis at 800-2400 nm using FT-NIR spectrometer. The spectrum of each tomato juice was collected twice: the first time as soon as the tomatoes were squeezed, centrifuged, filtered and the tomato juice had not undergone any oxidation process and the second measurement was taken after a month. Principal component analysis (PCA) and partial least squares discriminant analysis (PLSDA) were applied to discriminate between the two groups of spectra. The results show that differences between tomato juices before and after the storage period do exist attributed to changes in certain compounds of juice and excellent classification can be obtained after optimizing spectral pretreatment.

The potential of near-infrared (NIR) transmittance spectroscopy to nondestructively detect soluble solids contents (SSC) and pH in tomato juices was investigated. A total of 200 tomato juice samples were used for NIR spectroscopy analysis at 800-2400 nm using FT-NIR spectrometer. Multiplicative signal correcton (MSC), the first and second derivative were applied for preprocessing spectral data. The relationship between SSC, pH and FT-NIR spectra of tomato juice was analyzed via partial least-squares (PLS) regression, respectively. PLS regression models for SSC and pH in tomato juices show the high accuracy. The correlation coefficient (r), root mean square error of calibration (RMSEC) and root mean square error of validation (RMSEP), root mean square error of cross-validation (RMSECV) for SSC were 0.91582, 0.0703, 0.150 and 0.138, respectively, whereas those values for pH were 0.8997, 0.0333, 0.0316 and 0.0489, respectively. It is concluded that the NIR transmittance spectroscopy is promising for the fast and nondestructive detection of chemical components in tomato juices.

Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this paper, ultrafine noble metallic nanoparticles are incorporated into cauliflower-like porous magnetic metal–organic frameworks (MOFs). With the restriction effects of the pore/surface structure in the MOFs, “surfactant-free” metallic nanoparticles are successfully obtained on a 2–3 nm scale. In addition, both the thickness of MOFs shell and the content of noble metallic NPs are tunable on the MOFs coating. Moreover, the microspheres exhibit excellent performance for the catalytic reduction of p-nitrophenol with a turnover frequency of 3094 h−1. The uniform cavities in the MOFs shell provide docking sites for p-nitrophenol and act as confinement nanoreactors, which greatly improves the catalytic performance. Most importantly, the magnetically responsive microspheres can be easily recovered by a magnetic field and show excellent reusability. The as-prepared catalyst also shows good activity for the reduction of other nitrobenzenes. Consequently, this work provides a highly active, magnetically isolable, and recyclable catalyst, which can be used for various catalytic industrial processes. The fundamental model can be further employed in a variety of biomedical fields including drug delivery and biological molecules separation.