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Sample preparation, including extraction, separation, and purification, is a vital process for natural product analysis. As an attractive sample pretreatment method, magnetic solid‐phase extraction (MSPE) has gained plenty of attention, mainly due to its simpler operation, less consumption of organic solvents, and shorter processing time than traditional SPE. This updated review is devoted to summarizing the applications of MSPE based on different magnetic nanomaterials in the analysis of various natural products in complex matrixes, such as biological samples, plants, and Chinese herbal preparations in the past four years (2020–2023). The preparation and fabrication of different materials are briefly introduced. Furthermore, the extraction mechanism and interaction forces between adsorbent and analytes are elaborated, and the advantages and disadvantages of different adsorbents coupled with various analytical methods for MSPE of different natural products are summarized. Moreover, the future trends and opportunities for MSPE in the natural product analysis are discussed. It is expected that this work can provide updated information for future research on the applications of MSPE in such fields. [ABSTRACT FROM AUTHOR]

Colorimetric sensors are widely used for various sensing applications due to their specificity, sensitivity, cost-effectiveness, and ease of use. They have been developed to detect a range of substances including metal and non-metal ions, proteins, small molecules, gases, viruses and bacteria, DNA/RNA, acidity/base, and biomarkers in clinical diagnostics. Recent advancements in nanomaterials have played a significant role in the development of colorimetric sensors. This article provides an overview of the field, discussing the design and fabrication of sensors for various applications such as alkaline vapors, dopamine detection, uric acid detection, organic thiol analysis, H2O2 and glucose detection, HPV detection, metal ion detection, protein identification, synthetic food dye detection, and phenolic compound detection. These sensors offer promising applications in different fields, providing rapid, low-cost, and portable solutions for detection. The article also highlights the development of multifunctional sensors and the integration of colorimetric sensors with smartphones, color-recording devices, and optical sensing arrays, which have improved the portability, sensitivity, and specificity of detection. The article concludes that with further advancements in materials and analytical chemistry, colorimetric sensors will continue to contribute to the fields of chemical and biological sensing. [Extracted from the article]

With the increase of obesity incidence, the development of antiobesity drugs has aroused extensive interest. In this study, a simple and portable personal glucose meter (PGM) method based on the lipase-mediated reaction combined with molecular docking was developed for the screening of lipase inhibitors. Lipase can catalyse the hydrolysis of 4-acetamidophenyl acetate to form acetaminophen, which can directly trigger the reduction of K3[Fe(CN)6] to K4[Fe(CN)6] in the glucose test strips and generate an electrical signal that can be detected by the PGM. When lipase inhibitors exist, the yield of acetaminophen will be reduced and results in a corresponding decrease of the PGM signal. Therefore, the activity of lipase can be measured by the PGM. After optimization of the experimental conditions, the inhibitory activity of fourteen small-molecule compounds and fifteen natural product extracts on lipase were evaluated by the developed PGM method. The results indicate that tannic acid, (-)-epigallocatechin gallate, (-)-epigallocatechin, (-)-epicatechin gallate, and epicatechin have good inhibitory effect on lipase (% of inhibition higher than 40.0%). Besides, the natural product extracts of Galla Chinensis, lemon, and Rhei Radix et Rhizoma have a good inhibitory effect on lipase with % of inhibition of (97.5 ± 0.6)%, (88.1 ± 0.7)%, and (79.1 ± 1.6)%, respectively. Finally, the binding sites and modes of six small-molecule compounds on lipase were investigated by the molecular docking study. The results show that the developed PGM method is an effective approach for the discovery of potential lipase inhibitors. [ABSTRACT FROM AUTHOR]

Mussel‐inspired polydopamine has been widely used in capillary electrophoresis as a facile and universal tool for the surface modification of capillary, mainly due to its versatility, stability, strong adhesiveness, and biocompatibility properties. In this review, the recent development of mussel‐inspired surface chemistry with rapid deposition of polydopamine was introduced, and the recent applications of polydopamine in capillary electrophoresis (2011–July 2018) were summarized into four main aspects, namely, sample pretreatments, functional coatings, codeposition coatings, and intermediate coatings. Further study may be focused on clarifying the mechanisms of polydopamine formation and polydopamine‐assisted codeposition, and expanding coatings methods to plant polyphenols. [ABSTRACT FROM AUTHOR]

An online capillary electrophoresis (CE)-based thrombin (THR) immobilized enzyme microreactor (IMER) method was established to screen THR inhibitors in this study. S-2366 was used as chromogenic substrate for determination of THR activity and other kinetic constants. After continuously run for 50 times, the prepared IMER could still remain 89% of the initial immobilized enzyme activity. The Michaelis-Menten constant (K m ) of immobilized THR was measured as 0.514 mmol/L and the half-maximal inhibitory concentration (IC 50 ) and inhibition constant (K i ) of argatroban on THR were determined as 78.07 and 26.53 nmol/L, respectively, which indicated that CE-based THR IMER was successfully established and could be applied to screen THR inhibitors. Then the prepared IMER was used to investigate the inhibitory potency on THR of four main catechins in green tea including epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG). The results showed that ECG and EGCG had good THR inhibition activity and their inhibition rates at concentration of 200 μmol/L were 53.2 ± 3.8% and 55.8 ± 2.6%, respectively, which was in consistent with the results of microplate reader assay. Additionally, molecular docking results showed that the benzopyran groups of ECG and EGCG were inserted into the THR active pocket and interacted with residues LYS60F, TRP60D, TRY60A, IEU99, GLY216, HIS57 and SER195, but EC and EGC did not. Therefore, the developed CE-based THR IMER is reliable method for measuring THR inhibitory activity of natural inhibitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • A paper-based lateral flow sensor is developed for the detection of PG. • Detection of PG is achieved based on enzyme-mediated pectin viscosity change. • Combination of paper-based lateral flow sensor and smartphone method for PG detection. • The method exhibits good performance in high portability and label-free detection. In this study, a simple, convenient, and cost-effective paper-based lateral flow strip sensor combined with a smartphone was developed for the determination of polygalacturonase (PG) activity based on the modulation of viscosity of pectin solution, which can be visualized by the difference in the average diffusion distance on the pH indicator strips. Effects of the pectin concentration, enzymatic reaction time, the volume of diffusion liquid, and the diffusion time on the average diffusion distance were systematically investigated. For quantitative analysis of PG activity, the images of the pH indicator strips after lateral flow diffusion were collected by a smartphone and processed through Adobe Photoshop CS 5.1 software. Under the optimal conditions, the average lateral flow diffusion distance shows a good linear relationship with PG activity in the range of 0.025–0.80 U/mL, and the limit of quantification is 0.025 U/mL. Finally, the applicability of the proposed strategy was successfully verified by measuring PG activity in cucumber sample. The recoveries are in the range of 87.4%–96.7%. In short, the present study developed a convenient, low-cost, and accurate approach for on-site detecting of PG activity, especially in remote or resource-limited regions. [ABSTRACT FROM AUTHOR]

Hydrophilic interaction liquid chromatography, an alternative liquid chromatography mode, is of particular interest in separating hydrophilic and polar ionic compounds. Compared with traditional liquid chromatography techniques, hydrophilic interaction liquid chromatography offers specific advantages mainly including: (1) relatively green and water-soluble mobile phase composition, which enhances the solubility of hydrophilic and polar ionic compounds; (2) no need for ion-pairing reagents and high content of organic solvent, which benefits mass spectrometry detection; (3) high orthogonality to reverse-phase liquid chromatography, well adapted to two-dimensional liquid chromatography for complicated samples. Therefore, hydrophilic interaction liquid chromatography has been rapidly developed in many areas over the past decades. This review summarizes the recent progress (from 2012 to July 2016) of hydrophilic interaction liquid chromatography in pharmaceutical analysis, with the focus on detecting chemical drugs in various matrices, charactering active compounds of natural products and assessing biotherapeutics through typical structure unit. Moreover, the retention mechanism and behavior of analytes in hydrophilic interaction liquid chromatography as well as some novel hydrophilic interaction liquid chromatography columns used for pharmaceutical analysis are also described. [ABSTRACT FROM AUTHOR]

Thrombosis is considered to be closely related to several diseases such as atherosclerosis, ischemic heart disease and stroke, as well as rheumatoid arthritis, hyperuricemia, and various inflammatory conditions. More and more studies have been focused on understanding the mechanism of molecular and cellular basis of thrombus formation as well as preventing thrombosis for the treatment of thrombotic diseases. In reality, there is considerable interest in the role of natural products and their bioactive components in the prevention and treatment of thrombosis related disorders. This paper briefly describes the mechanisms of thrombus formation on three aspects, including coagulation system, platelet activation, and aggregation, and change of blood flow conditions. Furthermore, the natural products for antithrombosis by anticoagulation, antiplatelet aggregation, and fibrinolysis were summarized, respectively. [ABSTRACT FROM AUTHOR]

A polyhedral MIL-125-NH2@Pd nanoparticle with light-responsive oxidase-like activity was synthesized through a simple solvothermal method and was characterized by field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller analysis, etc. MIL-125-NH2@Pd can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) under light radiation without H2O2, indicating its intrinsic light-responsive oxidase-like characteristic. MIL-125-NH2@Pd shows a superior catalytic activity and higher affinity to TMB, compared to MIL-125-NH2, owing to the presence of homogenously distributed palladium (Pd) nanoparticles. The results of the mechanism study indicate the existence of ˙O2− and electron holes during the catalytic reaction of MIL-125-NH2@Pd. Furthermore, based on the excellent light-responsive oxidase-like activity and specific recognition capacity for casein phosphopeptides (CPP) of titanium ions (Ti4+) in MIL-125-NH2@Pd, a simple colorimetric sensing platform was developed for the determination of CPP in a linear range of 10–100 μg mL−1 with a limit of detection as low as 2.9 μg mL−1. Finally, the developed method was successfully employed in the sensitive and selective detection of CPP in spiked rabbit and rat plasma samples. This study may provide a reliable and highly efficient strategy to realize the excitation-responsive sensing applications of materials. [ABSTRACT FROM AUTHOR]

Searching for bioactive compounds from natural resources such as plant materials has become a focus for study. Several models, such as animal (biofluid, organ and tissue) and cellular (several kinds of cell lines), have traditionally been used for this purpose. As a fast, economic and effective way to identify or predict bioactive compounds in complex matrices, biochromatography has developed rapidly during the past years. Combing the properties of traditional chromatography and biomaterials, biochromatographic analysis possesses features of simultaneous screening, separation and structural identification for active compounds in a complex matrix. According to the process, biochromatography can be divided into offline and online approaches. For offline bioextraction, the biomaterials are used as the extraction phase and followed by routine chromatographic analysis. For online biochromatography, the biomaterials are directly used as the stationary phase for chromatographic analysis. This paper reviews the applications of offline bioextraction followed by chromatographic analysis and online biochromatography, including molecular, cell membrane and cell, and artificial biomembrane chromatography in the screening or predicting active compounds from natural sources. [ABSTRACT FROM AUTHOR]

Although hundreds of papers related to preparative gas chromatography (pGC) have been published since the late 1950s, the success of the GC technique has largely been associated with analytical instead of preparative purposes. Actually, pGC is an ideal alternative technique for the preparation of pure substances, especially volatile compounds. This paper reviews the papers (written in English) associated with pGC published over the period from the 1950s to the 2010s. For large scale preparation, large sample injection and vaporization, a high loading capacity column, a gas splitter at the end of the column and a special collecting device are fundamentally important for a pGC system. The primary components of pGC system, including injector, column, splitter, detector and collection traps, are briefly introduced. Furthermore, the applications of pGC in the separation and purification of volatile compounds from natural essential oils, in addition to the purification of isotopes, isomers and enantiomers are summarized. [ABSTRACT FROM AUTHOR]

Volatile chemicals are a group of very important compounds in natural products. Curcuma rhizome, which contains many bioactive volatile compounds, is a traditional Chinese medicine that has long been used for the treatment of several diseases. In the present study, a microemulsion electrokinetic chromatography (MEEKC) method was developed for the analysis of four volatile components in Curcuma rhizome, including germacrone, furanodiene, curcumenol and curdione. Experimental parameters, including the pH, type and concentrations of background electrolyte, and microemulsion compositions (type and concentrations of surfactant, co-surfactant and oil phase) were intensively investigated. Finally, the primary compounds in the methanol extract of Curcuma rhizome were separated within 30 min using a running buffer composed of 2.31% w/v (80 mmol/L) sodium dodecyl sulfate (SDS), 0.91% w/v (80 mmol/L) 1-octane, 6.95% w/v (937.5 mmol/L) 1-butanol and 1.88% w/v (312.5 mmol/L) propanol in a 5-mM borate buffer (pH 8.1). The contents of the four investigated compounds were determined in the rhizome from C. phaeocaulis. The results showed that the developed MEEKC method provided an alternative tool for the analysis of volatile components, especially those of heat-sensitive compounds from natural products. [ABSTRACT FROM AUTHOR]

Abstract: In present study, a capillary electrophoresis–mass spectrometry (CE–MS) method was developed for the simultaneous analysis of 12 nucleosides and nucleobases including cytosine, adenine, guanine, cytidine, cordycepin, adenosine, hypoxanthine, guanosine, inosine, 2′-deoxyuridine, uridine and thymidine in natural and cultured Cordyceps using 5-chlorocytosine arabinoside as an internal standard (IS). The CE separation conditions and MS parameters were optimized systematically for achieving good CE resolution and MS response of the investigated compounds. The optimum CE electrolyte was 100mM formic acid containing 10% (v/v) methanol. The optimum MS parameters were as follows: 75% (v/v) methanol containing 0.3% formic acid with a flow rate of 3μL/min was selected as the sheath liquid; the flow rate and temperature of drying gas were 6L/min and 350°C, respectively. The optimized CE–MS method was successfully applied for the simultaneous determination of 12 nucleosides and nucleobases in natural and cultured Cordyceps. On the basis of quantitative results, the total content of nucleosides is much higher in cultured Cordyceps (9138±4823μg/g for cultured C. sinensis; 3722±1446μg/g for C. militaris) than in natural ones (2167±412μg/g). However, the hypoxanthine (131±47μg/g) and inosine (335±90μg/g) are much higher in natural C. sinensis. Cordycepin, which is abundant in cultured C. militaris (2276.5±842.6μg/g), is only found in natural C. sinensis with very low content and cannot be detected in the cultured ones. [Copyright &y& Elsevier]

[Display omitted] • Quantitation of urea by urease-mediated chitosan viscosity change on paper-based sensor. • Chitosan solution viscosity is converted to distance-readout on paper-based sensor. • Combination of paper-based sensor and distance-readout method for urea POCT. In this study, a paper-based sensor combined with visual distance-readout technique for point of-care testing (POCT) of urea was developed by urease-mediated chitosan viscosity change. A series of factors that affect the performance of the sensor were investigated, including the type of filter paper, chitosan concentration, acetic acid concentration and enzymatic reaction conditions. Under optimal conditions, the proposed method for urea determination has good linearity between 3.8–15.1 mM. The limit of quantitation is 3.8 mM. Finally, the paper-based sensor was successfully applied to the determination of urea in two diesel exhaust fluid (DEF) samples. The recoveries of urea were 91.4 % and 109.9 % in DEF-1 and DEF-2, respectively. The present study provides a novel approach, which integrates paper-based sensor and visual distance-readout technique, for monitoring urea in POCT application, especially in remote or resource-limited regions. [ABSTRACT FROM AUTHOR]

The development of a facile and reliable assay for arsenic (As) detection is crucial for its pollution control, which is a well-known heavy-metal pollutant in the environment. In this work, an efficient colorimetric method was established for As(V) detection based on a novel cuboid-shape Mn-Urea nanozyme (UMnzyme) with arsenic-enhanced oxidase-like activity. The UMnzyme was prepared through the coordination of Mn ions and carbonyl groups in urea, which possesses outstanding oxidase-like activity that can generate the superoxide anion free radical (O2˙−) by catalyzing the dissolved O2, triggering the 3,3′,5,5′-tetramethylbenzidine (TMB) chromogenic reaction. Furthermore, the free oxygen atoms in UMnzyme provide potential sites to bind with As, in which the formation of As–O will not destroy the morphology and structure of UMnzyme. The capture of As by UMnzyme results in the improvement of its oxidase-like activity; therefore, a colorimetric method for As(V) detection was developed with a linear range of 12.5–250 μg L−1. The limit of detection was determined to be 2.4 μg L−1 (S/N = 3), which is lower than the threshold (10 ppb) recommended by the World Health Organization. Moreover, the developed method was applied in the detection of As(V) in environmental water, and the recoveries are 89.5–103.6%. In short, this study provides an efficient and reliable strategy for As(V) detection based on a novel Mn-based nanozyme and a new idea for the reasonable design of Mn-based nanozymes with enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Phytochemical investigation of Ampelocissus artemisiifolia Planch. led to the isolation of a new γ-pyrone,( E)-2-(2-hydroxypropyl)-6-(4-hydroxystyryl)-4 H-pyran-4-one ( 1), together with eight known compounds ( 2- 9). Their structures were identified on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. All of them were isolated from the genus Ampelocissus for the first time, while compounds 7, 8, and 9 were new for the family Vitaceae. [ABSTRACT FROM AUTHOR]

The high toxicity of arsenic (As) can cause irreversible harm to the environment and human health. In this study, the chlorin e6 (Ce6), which emits fluorescence in the infrared region, was introduced as the luminescence center, and the addition of copper ion (Cu2+) and As(V) provoked a regular change in fluorescence at 652 nm, whereas that of As(III) was 665 nm, which was used to optionally detect Cu2+, arsenic (As(III), and As(V)). The limit of detection (LOD) values were 0.212 μM, 0.089 ppm, and 1.375 ppb for Cu2+, As(III), and As(V), respectively. The developed method can be used to determine Cu2+ and arsenic in water and soil with good sensitivity and selectivity. The 1:1 stoichiometry of Ce6 with Cu2+ was obtained from the Job plot that was developed from UV–visible spectra. The binding constants for Cu2+ and As(V) were established to be 1.248 × 105 M−1 and 2.35 × 1012 M−2, respectively, using B–H (Benesi–Hildebrand) plots. Fluorescence lifetimes, B–H plots, FT–IR, and 1H-NMR were used to postulate the mechanism of Cu2+ fluorescence quenching and As(V) fluorescence restoration and the interactions of the two ions with the Ce6 molecule. [ABSTRACT FROM AUTHOR]

Differential proteomics, which has been widely used in studying of traditional Chinese medicines (TCMs) during the past 10 years, is a powerful tool to visualize differentially expressed proteins and analyzes their functions. In this paper, the applications of differential proteomics in exploring the action mechanisms of TCMs on various diseases including cancers, cardiovascular diseases, diabetes, liver diseases, kidney disorders and obesity, etc. were reviewed. Furthermore, differential proteomics in studying of TCMs identification, toxicity, processing and compatibility mechanisms were also included. This review will provide information for the further applications of differential proteomics in TCMs studies. [ABSTRACT FROM AUTHOR]

In this study, a simple and portable enzyme activity assay and inhibitor screening method was developed based on β-Glucosidase-mediated cascade reaction in a personal glucose meter (PGM). The inhibition of castanospermine (β-Glucosidase inhibitor) on β-Glucosidase leads to reducing the yields of glucose and saligenin produced by the catalysis hydrolysis of D (−)-Salicin. The ferricyanide (K 3 [Fe(CN) 6 ]) can be reduced by the products of glucose and saligenin to form ferrocyanide ([K 4 [Fe(CN) 6 ]) in the glucose strips, and thereby get the electron to generate PGM detectable signals. This strategy can realize the direct determination of glucose and saligenin using PGM as simple as measuring the glucose in blood. Under the optimum experimental conditions, quantitative detection of β-Glucosidase in crude almond sample was achieved within the ranges of 1.0–9.0 U/mL with the limit of detection of 0.45 U/mL. The recoveries of β-Glucosidase spiked with two different concentrations (3.0 and 6.0 U/mL) in the crude bitter almond extracts were determined as 96.2% and 84.3%, respectively. Furthermore, gallic acid, protocatechualdehyde, cryptochlorogenic acid, epigallocatechin, epicatechin and vanillic acid exhibited good inhibitory effect (all higher than 40%) on β-Glucosidase. In addition, tea polyphenol extracts of raw Pu-erh and Fuding white tea had good inhibition potency and the % of inhibition were (29.0 ± 3.5)% and (21.1 ± 2.2)% on β-Glucosidase, respectively. Finally, molecular docking study indicated that hydrogen bonding plays an important role in the interaction between the compounds and β-Glucosidase. The enzyme activity assay and inhibitor screening method developed in present study using PGM based on β-Glucosidase-mediated cascade reaction would be of value for expanding the application of PGM in non-glucose target analysis. Image 1 • A portable method for β-Glucosidase (β-Glu) activity assay and inhibitor screening. • Converting chemical signal to personal glucose meter (PGM) detectable signal. • Reduction of K 3 [Fe(CN) 6 ] to K 4 [Fe(CN) 6 ] via β-Glu-mediated cascade reaction in PGM. • The developed method expands the application of PGM in non-glucose target analysis. [ABSTRACT FROM AUTHOR]

Plant polyphenols can form functional coatings on various materials through self-polymerization. In this paper, a series of modified capillary columns, which possess diversity of charge characteristics for modulating electroosmotic flow (EOF), were prepared by one-step co-deposition of gallic acid (GA), a plant-derived polyphenol monomer, and branched polyethyleneimine (PEI). The physicochemical properties of the prepared columns were characterized by Fourier transform infrared spectroscopy (FT-IR), UV–Vis spectroscopy and scanning electron microscopy (SEM). The magnitude and direction of EOF of GA/PEI co-deposited columns were modulated by changing a series of coating parameters, such as post-incubation of FeCl 3 , co-deposition time, and deposited amounts of GA and PEI with different relative molecular mass (PEI-600, PEI-1800, PEI-10000, and PEI-70000). Furthermore, the separation efficiencies of the prepared GA/PEI co-deposited columns were evaluated by separations of small molecules, including organic acids, polar nucleotides, phenols, nucleic acid bases and nucleosides. Results indicated that modulating of EOF plays an important role in enhancing the separation performance and reversing the elution order of the analytes. Finally, the developed method was successfully applied to quantitative analysis of acidic compounds in four real samples. The recoveries were in the range of 73.5%–85.8% for citric acid, benzoic acid, sorbic acid, salicylic acid and ascorbic acid in beverage and fruit samples, 101.6%–104.9% for cinnamic acid, vanillic acid, and ferulic acid in Angelica sinensis sample, while 84.6%–97.8% for guanosine-5′-monophosphate, uridine-5′-monophosphate, cytosine-5′- monophosphate and adenosine-5′-monophosphate in Cordyceps samples. These results indicated that the co-deposition of plant polyphenol-inspired GA/PEI coatings can provide new opportunities for EOF modulation of capillary electrophoresis. • A facile method for surface modification & EOF modulation in CE was developed. • PDA-like coating with controllable surface charge properties was fabricated in CE. • This strategy simplified the modification methodology for tailoring the EOF in CE. [ABSTRACT FROM AUTHOR]

Phenolic compounds are one of the main organic pollutants in the environment that can seriously affect ecosystems, even at very low concentrations. Due to the resistance of phenolic compounds to microorganisms, conventional biological treatment methods face challenges in effectively addressing this pollution problem. In this study, a novel laccase mimic (Tris-Cu nanozyme) is prepared using a simple and rapid synthesis strategy based on the coordination of copper ions and amino groups in Tris(hydroxymethyl)aminomethane (Tris). It is found that the Tris-Cu nanozyme exhibits good catalytic activity against a variety of phenolic compounds, the Km, Vmax and Kcat are determined to be 0.18 mM, 15.62 μM·min−1 and 1.57 × 107 min−1 using 2,4-dichlorophenol (2,4-DP) as the substrate, respectively. Then, based on the laccase-like activity of the Tris-Cu nanozyme, a novel colorimetric method for 2,4-DP (the limit of detection (LOD) = 2.4 μM, S/N = 3) detection in the range of 10–400 μM was established, and its accuracy was verified by analyzing tap and lake water samples. In addition, the Tris-Cu nanozyme shows excellent removal abilities for six phenolic compounds in experiments. The removal percentages for 2,4-DP, 2-chlorophenol (2-CP), phenol, resorcinol, 2,6-dimethoxyphenol (2,6-DOP), and bisphenol A (BPA) are 100%, 100%, 100%, 100%, 87%, and 81% at 1 h, respectively. In the simulated effluent, the Tris-Cu nanozyme maintains its efficient catalytic activity towards 2,4-DP, with a degradation percentage of 76.36% at 7 min and a reaction rate constant (k0) of 0.2304 min−1. Therefore, this metal–organic complex shows promise for applications in the monitoring and degrading of environmental pollutants. [ABSTRACT FROM AUTHOR]

A core–shell-derived structural magnetic zeolite imidazolate framework-67 (Fe3O4-COOH@ZIF-67) nanocomposite was fabricated through a single-step coating of zeolite imidazolate framework-67 on glutaric anhydride-functionalized Fe3O4 nanosphere for the magnetic solid-phase extraction (MSPE) of theophylline (TP). The Fe3O4-COOH@ZIF-67 nanocomposite was characterized through scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, Zeta potential analysis, X-ray diffraction, Brunauer–Emmett–Teller, and vibrating sample magnetometer. The material has a high specific surface area and good magnetism, which maintains the regular dodecahedron structure of ZIF-67 without being destroyed by the addition of Fe3O4-COOH nanospheres. The Fe3O4-COOH@ZIF-67 can rapidly adsorb TP mainly through the strong coordination interaction between undercoordinated Co2+ on ZIF-67 and –NH from imidazole of TP. The adsorption and desorption conditions, such as the amount of adsorbent, adsorption time, pH value, and elution solvent, were optimized. The kinetics of TP adsorption on Fe3O4-COOH@ZIF-67 was found to follow pseudo-second-order kinetics. The Langmuir model fits the adsorption data well and the maximum adsorption capacity is 1764 mg/g. Finally, the developed MSPE-HPLC method was applied in the enrichment and analysis of TP in four tea samples and rabbit plasma. TP was not detected in oolong tea and rabbit plasma, and its contents in jasmine tea, black tea, and green tea are 5.80, 4.31, and 1.53 μg/g, respectively. The recoveries of spiked samples are between 74.41% and 86.07% with RSD in the range of 0.81–3.83%. The adsorption performance of Fe3O4-COOH@ZIF-67 nanocomposite was nearly unchanged after being stored at room temperature for at least 80 days and two consecutive adsorption–desorption cycles. The results demonstrate that Fe3O4-COOH@ZIF-67 nanocomposite is a promising magnetic adsorbent for the preconcentration of TP in complex samples. [ABSTRACT FROM AUTHOR]

A biomimetic mineralization method was used in the facile and rapid preparation of nanoflowers for immobilizing alcohol dehydrogenase (ADH). The method mainly uses ADH as an organic component and zinc phosphate as an inorganic component to prepare flower-like ADH/Zn3(PO4)2 organic-inorganic hybrid nanoflowers (HNFs) with the high specific surface area through a self-assembly process. The synthesis conditions of the ADH HNFs were optimized and its morphology was characterized. Under the optimum enzymatic reaction conditions, the Michaelis-Menten constant (Km) of ADH HNFs (β-NAD+ as substrate) was measured to be 3.54 mM, and the half-maximal inhibitory concentration (IC50) of the positive control ranitidine (0.2–0.8 mM) was determined to be 0.49 mM. Subsequently, the inhibitory activity of natural medicine Penthorum chinense Pursh and nine small-molecule compounds on ADH was evaluated using ADH HNFs. The inhibition percentage of the aqueous extract of P. chinense is 57.9%. The vanillic acid, protocatechuic acid, gallic acid, and naringenin have obvious inhibitory effects on ADH, and their percentages of inhibition are 55.1%, 68.3%, 61.9%, and 75.5%, respectively. Moreover, molecular docking analysis was applied to explore the binding modes and sites of the four most active small-molecule compounds to ADH. The results of this study can broaden the application of immobilized enzymes through biomimetic mineralization, and provide a reference for the discovery of ADH inhibitors from natural products. [ABSTRACT FROM AUTHOR]

Herein, a Co–Fe Prussian blue analogue nanocube (Co–Fe PBA NC) was prepared in situ via a simple and rapid coprecipitation method at room temperature, and the synthesized nanocube was systematically characterized. The Co–Fe PBA NC was proven to have intrinsic oxidase-like activity, which can catalyze the production of reactive oxygen species, such as superoxide anions (O2˙−), hydroxyl radicals (˙OH), and singlet oxygen (1O2), in a dissolved oxygen system without the presence of hydrogen peroxide (H2O2). By making full use of the oxidase-like activity of the Co–Fe PBA NC and using the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB), a colorimetric sensor was fabricated for the detection of ascorbic acid (AA) and its related biological enzymes' activities, including alkaline phosphatase (ALP), α-glucosidase (α-Glu), and ascorbic acid oxidase (AAO), in human serum. This study presents an oxidase mimic that can be synthesized via a simple, rapid, and low-cost method, which overcomes the defects of cumbersome and time-consuming synthetic process, dependence on professional instruments and high cost of some previously reported nanozymes. In addition, this study provides a new multifunctional colorimetric sensing platform for AA and its related biological enzymes, showing great potential in biological assays. [ABSTRACT FROM AUTHOR]

In this study, 3,3′,5,5′-tetramethylbenzidine (TMB) was selected as a chromogenic substrate to evaluate the light-responsive oxidase-like activity of different zeolitic imidazolate frameworks (ZIFs). The synthesized ZIFs were systematically characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. Several main operational parameters, including ZIFs and TMB concentrations, pH value, radiation time, and working current, in the reaction process were optimized. The kinetic measurement results show that ZIF-90 exhibits higher affinity to the substrate than horseradish peroxidase. Furthermore, given that adenosine triphosphate (ATP) can specifically combine with Zn2+ binding site and destroy the structure of ZIF-90, a specific and sensitive colorimetric method was established for the quantitative detection of ATP within the range 10 − 240 μM. In addition, on the basis that phenolic pollutants can impact the reaction kinetics diversely on different ZIFs, a sensor array was constructed and successfully applied to differentiate five phenolic pollutants in lake water samples. This work is expected to shed light on the establishment of ZIF-based light-responsive oxidase-like nanozymes for the highly selective colorimetric detection and sensor array. [ABSTRACT FROM AUTHOR]

A magnetic porous carbon NH2‐MIL‐101‐C was synthesized through a one‐step carbonization process using NH2‐MIL‐101(Fe) as the precursor. The morphology, structure, magnetic behavior, and porosity of the as‐prepared NH2‐MIL‐101‐C were characterized. The results show that NH2‐MIL‐101‐C has a high Brunauer‐Emmett‐Teller surface area (213.7 m2/g), a large pore volume (0.2 m3/g), and a good magnetic property (23.4 emu/g). The NH2‐MIL‐101‐C was first used as a magnetic solid‐phase extraction adsorbent for the extraction of five anthraquinones from rhubarb. The main parameters that will affect the extraction efficiency were investigated. Under the optimized conditions, good linearity for the five anthraquinones was obtained with the R2 higher than 0.9910. The limits of detection and limits of quantitation for the analytes are 0.018−0.042 and 0.050−0.140 μg/mL, respectively. [ABSTRACT FROM AUTHOR]

In this study, a simple colorimetric method was established to detect copper ion (Cu2+), sulfathiazole (ST), and glucose based on the acetylcholinesterase (AChE)-like activity of zeolitic imidazolate framework-8 (ZIF-8). The AChE-like activity of ZIF-8 can hydrolyze acetylthiocholine chloride (ATCh) to thiocholine (TCh), which will further react with 5,5′-dithiobis (2-nitrobenzoic acid) (DTNB) to generate 2-nitro-5-thiobenzoic acid (TNB) that has a maximum absorption peak at 405 nm. The effects of different reaction conditions (buffer pH, the volume of ZIF-8, reaction temperature and time, and ATCh concentration) were investigated. Under the optimized conditions, the value of the Michaelis-Menten constant (Km) is measured to be 0.83 mM, which shows a high affinity toward the substrate (ATCh). Meanwhile, the ZIF-8 has good storage stability, which can maintain more than 80.0% of its initial activity after 30 days of storage at room temperature, and the relative standard deviation (RSD) of batch-to-batch (n = 3) is 5.1%. The linear dependences are obtained based on the AChE-like activity of ZIF-8 for the detection of Cu2+, ST, and glucose in the ranges of 0.021–1.34 and 5.38–689.66 µM, 43.10–517.24 µM, and 0.0054–1.40 mM, respectively. The limit of detections (LODs) are calculated to be 20.00 nM, 9.25 µM, and 5.24 µM, respectively. Moreover, the sample spiked recoveries of Cu2+ in lake water, ST in milk, and glucose in strawberry samples were measured, and the results are in the range of 98.4–115.4% with the RSD (n = 3) lower than 3.3%. In addition, the method shows high selectivity in the real sample analysis. [ABSTRACT FROM AUTHOR]

An effective, selective, and multicolor colorimetric assay for Cu2+ detection based on the regulation of peroxidase-like nanozyme-mediated etching of gold nanorods (Au NRs) is proposed. Cu2+-creatinine complex is selected as the nanozyme that exhibits excellent peroxidase-like activity even in the case of low concentration of Cu2+, which can catalyze 3,3,5,5-tetramethylbenzidine (TMB) to produce oxidized TMB (TMB+) in the presence of hydrogen peroxide, and TMB+ is oxidized to generate TMB2+ after adding H+, and the TMB2+ can etch Au NRs. The determination of Cu2+ is achieved based on the blue shift of the longitudinal localized surface plasmon resonance peak of Au NRs. Under the optimal conditions, the developed colorimetric assay exhibits high sensitivity for the detection of Cu2+ (limit of detection is 0.034 μM) with a wide linear range of 0.05–4.0 μM (R2 = 0.987). The solution shows a rainbow-like color in response to the increase of Cu2+ concentration, which can realize the semi-quantitative detection of Cu2+ by naked eyes. In addition, the developed method exhibits excellent selectivity for Cu2+-detection. The established method was used for the determination of Cu2+ in lake water, soil, and normal human serum with satisfactory recovery of spiked samples. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance The flower of Edgeworthia gardneri (Wall.) Meisn., locally named “Lvluohua, 绿萝花”, has been widely used as Tibetan folk medicine for the treatment of metabolic diseases for a long time. Aim of this study To evaluate the anti -adipogenesis effect of ethyl acetate extract of the flower of E. gardneri (EEG extract) in 3T3-L1 adipocytes. Materials and methods Obesity-related parameters such as lipid accumulation and TG content were determined by Oil red O staining and enzymatic kit, respectively. Western blotting was used to determine the expressions of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein-α (C/EBPα), phosphorylated adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC). Moreover, main constituents of EEG extract were analyzed by high performance liquid chromatography (HPLC). Results EEG extract decreased the lipid and triglyceride (TG) accumulations during the differentiation process and down-regulated the adipogenesis-related transcriptional factors PPARγ and C/EBPα. EEG extract treatment increased AMPK and ACC phosphorylation. In addition, pretreatment with AMPK inhibitor, weakened the inhibitory effects of EEG extract on the expressions of PPARγand C/EBPα. HPLC analysis indicated that tiliroside was the main constituent in EEG extract. Conclusions These results suggest that EEG extract may exert anti-adipogenic effects through modulation of the AMPK signaling pathway. [ABSTRACT FROM AUTHOR]

This work describes a simple and reliable colorimetric method based on the gold nanoparticles without any modification, which can realize the rapid, sensitive, and quantitative detection of lead (Pb2+) and copper (Cu2+) ions, providing a reference for monitoring metal ions in the environmental water. When Pb2+ was added to the gold nanoparticles solution containing a low concentration of L‐Cysteine, the combination of Pb2+ and L‐Cysteine can induce the aggregation of gold nanoparticles. On the contrary, Cu2+ can catalyze the oxidation of L‐Cysteine and destroy the formation of the Au‐S bond between L‐Cysteine and gold nanoparticles, thereby preventing the aggregation of gold nanoparticles. As the ultraviolet‐visible spectrum of gold nanoparticle solution is closely related to their aggregation status, the Cu2+ and Pb2+ can be determined. The calibration curves, which are constructed based on ratios of the absorbance at 650 nm and 520 nm of gold nanoparticles, display good linearity in the range of 50.0−2.5 × 103 nM for Pb2+ and 25.0−300.0 nM for Cu2+, respectively. The limits of quantitation of Pb2+ and Cu2+ are determined to be 50.0 and 25.0 nM, respectively. In addition, the spiked recoveries of Pb2+ and Cu2+ in real water samples are 94.6−112.5 and 87.3−114.7% with a relative standard deviation of less than 6.3%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mild-condition synthesized metal-complex nanozymes in the colorimetric and fluorescence analysis are reviewed. • The mild-condition synthesis processes of metal-complex nanozymes are discussed. • Strategy in developing colorimetric and fluorescent assays with high performance and specificity are summarized. The metal complexes, which are prepared through the coordination of metal ions with organic ligands, have various characteristics such as high porosity and specific surface area. In recent years, the metal complexes with enzyme-like activities have been widely used in colorimetric and fluorescence analysis. The synthesis process of metal complexes under mild conditions is particularly significant as it is not only easy to operate but also safe. In this article, the synthesis processes, catalytic mechanisms, activity regulation methods, and recent research progress of metal-complex nanozymes in the past years (2018 to present) have been summarized. Furthermore, the applications of metal-complex nanozymes-based biosensors in colorimetric and fluorescence detection of various analytes, such as antibiotics, metal ions, mycotoxins, pathogens, pesticides, and proteins, have been summarized and discussed. This review is prospective to promote the further applications of metal complexes with enzyme-like activity synthesized under mild conditions. [ABSTRACT FROM AUTHOR]

A Mn decorated zeolitic imidazolate framework-90 (ZIF-90) nanozyme (Mn/ZIF-90) was constructed through an effective and rapid post-synthetic strategy for the first time. The Mn in Mn/ZIF-90 exists in mixed valence states, which is doped to the ZIF-90 through the formation of Mn–O bond. The Zn–N coordination structure of ZIF-90 may change the electronic arrangement of oxygen atoms in the free carbonyl groups (–CHO), allowing the coordination of Mn with O. The prepared Mn/ZIF-90 possesses outstanding oxidase-like activity and remarkable stability. Besides, the catalytic activity of Mn/ZIF-90 can be inhibited in the presence of H 2 O 2. Therefore, using the Mn/ZIF-90-triggered chromogenic reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) as an amplifier, a versatile enzyme cascade-based colorimetric method for the detection of glucose and choline with good sensitivity and selectivity was developed. The linear ranges for glucose and choline are 6.25–500 μM and 5–1000 μM, respectively. Furthermore, the developed method was applied in the detection of glucose and choline in rabbit plasma samples, and the recoveries are 89.5–107.3 % and 96.0–109.3 %, respectively. In short, the simple and efficient post-synthetic doping method may provide a new thought for the rational designs of enzyme mimics with improved catalytic performance. Moreover, the colorimetric method based on the excellent catalytic activity of Mn/ZIF-90 may be extended to detect other H 2 O 2 -generating or consuming molecules and evaluate the activity of bio-enzymes that can catalyze the generation of glucose or choline. [Display omitted] • A novel and efficient post-synthetic strategy for Mn doping is presented. • Mn-decorated ZIF-90 (Mn/ZIF-90) with excellent oxidase-like activity is prepared. • The mixed valence state Mn endows the excellent oxidase-like activity to Mn/ZIF-90. • A colorimetric method for glucose and choline detection is developed based on Mn/ZIF-90. • The colorimetric method has potential to detect H 2 O 2 generating or consuming molecules. [ABSTRACT FROM AUTHOR]

A rapid, portable, and cost-effective method using personal glucose meter (PGM) for quantitative analysis of hydrogen peroxide (H 2 O 2) was established based on ascorbate oxidase (AAO)-catalyzed reaction for the first time. Ascorbic acid (AA) can rapidly reduce ferricyanide (K 3 [Fe(CN) 6 ]) to ferrocyanide (K 4 [Fe(CN) 6 ]) in the glucose test strip and transfer electron to the electrode to generating a PGM detectable signal. Thus, the concentration of AA can be directly determined by the PGM as simple as measuring the blood glucose. On the other hand, AAO can catalyze the reduction of H 2 O 2 and produce an enzyme-peroxide complex, which decreases the yields of dehydroascorbic acid formed by the oxidation of AA, resulting in the increase in PGM detectable signal of residual ascorbic acid (re-AA). Therefore, the concentration of H 2 O 2 is proportional to the concentration of re-AA. After optimization of the experimental conditions, the developed method can be used to detect H 2 O 2 at linear range of 2.5–5 × 103 μM with the quantification limit of 2.5 μM. In addition, the satisfactory spiked recoveries (95.3–108.9 %) of real samples (i.e., tap water, contact lens solution, medical hydrogen peroxide, and normal human serum) confirm its feasibility for practical applications. In short, this study provides a feasible PGM-based method for H 2 O 2 detection with simple operations. [Display omitted] • A simple, rapid and portable assay for quantitation of hydrogen peroxide. • The method based on the reduction of K 3 [Fe(CN) 6 ] to K 4 [Fe(CN) 6 ] via AA-triggered reaction. • The developed method expands the application of PGM in non-glucose target analysis. [ABSTRACT FROM AUTHOR]

In this work, a magnetic octahedral metal‐organic framework (Fe3O4@NH2‐MIL‐101(Fe)) was synthesized for the magnetic solid‐phase extraction of three anthraquinones, including aloe‐emodin, emodin, and physcion, in rhubarb. The Fe3O4@NH2‐MIL‐101(Fe) exhibits a high specific surface area of 259.2 m2/g with an average pore size of 6.0 nm and high magnetic responsivity of 23.4 emu/g, which may be used as an adsorbent for rapid preconcentration and separation of target analytes. The main parameters for magnetic solid‐phase extraction of anthraquinones, including the amount of adsorbent, extraction time, extraction temperature, extraction pH, elution solvent, and elution time, were systematically optimized. The whole extraction process requires a very low amount of adsorbent and a small volume of the sample. Besides, under the optimized conditions, the method shows satisfactory spiked recovery for anthraquinones in the range of 93.3–109.1% and the limits of detection are 1.7–3.4 ng/mL. The relative standard deviations for intra‐ and inter‐day precision are 0.2–1.3% and 0.2–0.6%, respectively. The experimental results indicate that the developed method is feasible for the analysis of anthraquinones in rhubarb. [ABSTRACT FROM AUTHOR]

The peroxidase-like activity of vitamin B6 (VB6) was firstly demonstrated by catalyzing the peroxidase chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) at the existence of H2O2. The influence of different factors on the catalytic property of VB6, including pH, temperature, VB6 concentration, and incubation time, were investigated. The steady-state kinetic study results indicate that VB6 possesses higher affinity to H2O2 than natural horseradish peroxidase and some other peroxidase mimics. Besides, the radical quenching experiment results confirm that hydroxyl radical (•OH) accounts for the catalytic process. Based on the excellent peroxidase-like catalytic activity of VB6, the colorimetric methods for H2O2 and gallic acid (GA) detection were developed by measuring the absorbance variance of the catalytic system. Under the optimal conditions, the linear ranges of the methods for H2O2 and GA determination with good selectivity are 50.0–600.0 μM and 10.0–50.0 μM, respectively. In addition, the developed method was applied in the detection of H2O2 in milk samples and evaluation of total antioxidant capacity of different tea infusions. This study may broaden the application prospect of VB6 in environmental and biomedical analysis fields, contribute to profound insight of the physiological functions of VB6, as well as lay foundation for further excavation of small-molecule peroxidase mimics. [ABSTRACT FROM AUTHOR]

A novel MOF@HOF composite that can serve as a matrix for analysis of small molecules by MALDI-TOF-MS was fabricated through a simple solvothermal method. Taking falvonoids as an example, this composite/matrix presents high desorption/ionization efficiency, low background interference, high salt tolerance, and satisfactory signal reproducibility for MALDI-TOF-MS analysis. [ABSTRACT FROM AUTHOR]

In this study, the poly (sodium 4‐styrenesulfonate)‐mediated calcium carbonate magnetic microspheres were prepared by a simple spontaneous biomimetic mineralization method to immobilize kallikrein. The immobilized kallikrein can be easily separated from the reaction mixture by an external magnet. The structural properties of the materials were studied by several characterization techniques. Subsequently, the immobilized kallikrein enzyme activity and stability were studied. Moreover, the inhibitory potency of ten natural compounds on kallikrein was evaluated by combining with capillary electrophoresis analysis. The immobilized kallikrein exhibited optimum pH and temperature at 7.5 and 75°C, respectively. After seven successive cycles, the immobilized kallikrein retained 82% of its initial activity. Furthermore, the Michaelis–Menten constant (Km) and the half‐maximal inhibitory concentration (IC50) of serine protease inhibitor on the immobilized kallikrein were determined to be 3.30 mM and 67.04 μM, respectively. In addition, berberine, evodine, coptisine, and jatrorrhizine among the ten natural compounds showed good inhibitory activity on the immobilized kallikrein, and their % of inhibition were (43.1 ± 1.7), (34.4 ± 1.9), (38.0 ± 1.7), and (28.5 ± 1.0)%, respectively. These results indicate that the biomimetic mineralization synthetic magnetic microsphere is an efficient method for kallikrein immobilization. [ABSTRACT FROM AUTHOR]

Highlights: [•] Chemical structure of konjac glucomannan from others’ researches. [•] Physiochemical properties of konjac glucomannan. [•] Progress of modified konjac glucomannan as excipients in OCDDS. [•] Future research value for konjac glucomannan in OCDDS. [Copyright &y& Elsevier]

[Display omitted] • New Mn coordination polymer nanoparticles (Mn-IMZs CPNs) with oxidase-like activity. • Mixed valence state of Mn endows excellent oxidase-like activity to Mn-IMZs CPNs. • Colorimetric method for glutathione detection with a wide linear range is developed. • A discriminative detection strategy of glutathione from cysteine is developed. Novel kinds of manganese coordination polymer nanoparticles (Mn-IMZs CPNs) were fabricated through self-assemble of imidazole with Mn2+ ions in aqueous solution. The prepared Mn-IMZs CPNs, with remarkable stability, exhibit excellent oxidase-like activity that can effectively catalyze the conversion of the dissolved O 2 to O 2 •−, turning the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (ox-TMB). Based on the inhibitory effect of glutathione (GSH) on the TMB oxidation, a rapid and highly sensitive colorimetric method for the detection of GSH was developed, and the linear ranges are 1.25–50 μM and 50–112.5 μM. Besides, the discriminative detection of GSH from cysteine was achieved by using the time lag between N-ethylmaleimide on the destruction of thiol compounds. Finally, the developed method was successfully applied in the quantification of GSH in tablets and rabbit plasma with high accuracy and good recovery. [ABSTRACT FROM AUTHOR]

Yolk-shell structure magnetic metal–organic framework nanoparticles were prepared via post solvothermal method and employed as a magnetic solid-phase extraction adsorbent for selective pre-concentration of 5′-ribonucleotides by π stacking interaction, hydrogen bonding, and the strong interaction between titanium ions (Ti4+) and phosphate group. The properties of the materials were confirmed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, vibrating sample magnetometer, infrared spectroscopy, thermogravimetric analysis, and Brunauer–Emmett–Teller analysis. The main parameters affecting the adsorption–desorption process, including adsorbent amount, incubation time, incubation temperature, sample pH, shaking speed, elution solution, and elution time, were systematically optimized. Finally, 1.0 mg of adsorbent mixed with 1.0 mL sample solution (10.0 mmol⋅L−1 NaCl, pH 3.0) and shaken at 135 rpm for 5 min at 40 °C, washed with 1.0 mL Na3PO4-NH3∙H2O under vortex for 5 min were selected as optimized adsorption–desorption conditions. The binding performance of adsorbent towards five nucleotides was evaluated by static adsorption experiments. The data are well-fitted to the Langmuir isotherm model and the maximum adsorption capacity is 27.8 mg g−1 for adenosine 5′-monophosphate. The limit of detection of the method is 19.44–38.41 ng mL−1. Under the optimal conditions, the adsorbent was successfully applied to magnetic solid-phase extraction and high performance liquid chromatography determination of five nucleotides in octopus, chicken, fish, and pork samples. [ABSTRACT FROM AUTHOR]

In this study, a magnetic yolk-shell structured metal-organic framework material (Fe3O4@YS-UiO-66-NH2) is prepared by the directional etching of Co2+/peroxymonosulfate and in situ magnetization. The characteristic properties of the material were investigated by using field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, Brunauer-Emmett-Teller, and contact angle test. The Fe3O4@YS-UiO-66-NH2 shows the advantages of large surface area, good magnetic property, and satisfactory stability, as well as giving high affinity to alkaloids (ALs) via hydrophilic interaction, hydrogen bonding, and π-π interaction. The results of static adsorption experiment indicate that the Fe3O4@YS-UiO-66-NH2 possesses high adsorption capacity towards ALs and the adsorption behaviors are fitted with Langmuir adsorption isotherm model. Furthermore, a magnetic solid-phase extraction using Fe3O4@YS-UiO-66-NH2 and HPLC method was developed for the analysis of ALs in spiked samples with the recovery of 89.6–100.8%. In addition, the proposed method was successfully applied in the pharmacokinetics study of berberine, coptisine, and palmatine in the rat. In short, the developed method might be used for high-efficient recognition and determination of ALs in plasma sample, which would also provide a new way to fabricate magnetic functionalized metal-organic framework in separation science. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a rapid and repeatable microemulsion electrokinetic chromatography (MEEKC) method was developed for the simultaneous determination of three isomers (α-, β- and γ-asarone) in Acorus tatarinowii by using ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) as oil phase. Experimental parameters including the microemulsion compositions (concentrations of surfactant, co-surfactant and oil phase), pH, concentration of borate buffer, capillary temperature and voltage were intensively investigated. Finally, the main compounds in the methanol extract of A. tatarinowii were well separated within 11min using a running buffer composed of 40mmol/L sodium dodecyl sulfonate (SDS), 2.0mol/L n-propanol, 8mmol/L [BMIM]PF6 in 10mmol/L borate buffer of pH 9.5. The developed method was applied to determine the contents of α-, β- and γ-asarone in A. tatarinowii from five different producing areas in China (Anhui, Hebei, Sichuan, Zhejiang and Chongqing). The results indicated that the contents of three asarones are quite different in the investigated A. tatarinowii samples. On the other hand, the MEEKC with ionic liquid as oil phase should be a promising method for the analysis of volatile components especially isomers in medicinal herbs. [Copyright &y& Elsevier]

• PA/Cu 3 (PO 4) 2 ·3H 2 O nanozyme is prepared using a facile co-precipitation method. • The peroxidase-like activity of PA/Cu 3 (PO 4) 2 ·3H 2 O is firstly demonstrated. • A method is developed for improving the peroxidase-like activity of metal phosphate. The Cu 3 (PO 4) 2 ·3H 2 O was modified by hydrophilic phytic-acid (PA/Cu 3 (PO 4) 2 ·3H 2 O) using a facile co-precipitation method. The peroxidase-like activities of Cu 3 (PO 4) 2 ·3H 2 O and PA/Cu 3 (PO 4) 2 ·3H 2 O were demonstrated by catalyzing the peroxidase substrate 3,3,5,5-tetramethylbenzidine in the presence of hydrogen peroxide. The catalytic activity of PA/Cu 3 (PO 4) 2 ·3H 2 O is about four times than that of Cu 3 (PO 4) 2 ·3H 2 O, indicating that the peroxidase activity can be enhanced by the introduction of PA. Then, the as-prepared PA/Cu 3 (PO 4) 2 ·3H 2 O was used to develop a colorimetric method for hydrogen peroxide detection with linear range of 0.1–5.0 mM and detection limit of 0.079 mM. Finally, the applicability of PA/Cu 3 (PO 4) 2 ·3H 2 O-based assay was validated by the detection of hydrogen peroxide in milk samples, and the recoveries were 92.4%-101.7%. The developed strategy highlights opportunity for the design of inorganic materials with enhanced inherently peroxidase-mimicking performance using PA. [ABSTRACT FROM AUTHOR]

In drug discovery, one of the most important tasks is to find novel and biologically active molecules. Given that only a tip of iceberg of drugs was founded in nearly one-century's experimental exploration, it shows great significance to use in silico methods to expand chemical database and profile drug-target linkages. In this study, a web server named ChemGenerator was proposed to generate novel activates for specific targets based on users' input. The ChemGenerator relies on an autoencoder-based algorithm of Recurrent Neural Networks with Long Short-Term Memory by training of 7 million of molecular Simplified Molecular-Input Line-Entry System as the basic model, and further develops target guided generation by transfer learning. As results, ChemGenerator gains lower loss (<0.01) than existing reference model (0.2~0.4) and shows good performance in the case of Epidermal Growth Factor Receptor. Meanwhile, ChemGenerator is now freely accessible to the public by http://smiles.tcmobile.org. In proportion to endless molecular enumeration and time-consuming expensive experiments, this work demonstrates an efficient alternative way for the first virtual screening in drug discovery. [ABSTRACT FROM AUTHOR]

In this study, an effective and portable method for enzyme activity detection and inhibitory activity evaluation was developed based on the alkaline phosphatase (ALP)-mediated reaction in a personal glucose meter (PGM). In this method, ALP catalyzes the hydrolysis of substrate amifostine (WR-2721) to produce ethanethiol (WR-1065), which can trigger the reduction of ferricyanide (K3[Fe(CN)6]), an electron transfer mediator in glucose test strips, to ferrocyanide ([K4Fe(CN)6]) and generate a PGM-detectable signal. Thus, WR-1065 can be directly quantified by a PGM as simply as detecting glucose in blood. After being systematically optimized, the method was applied to evaluate the inhibitory activity of ten small-molecule compounds and six Cordyceps sinensis (CS) extracts on ALP. The results showed that adenosine-5-monophosphate and theophylline had high inhibitory activity, but two CS extracts have promotion potency on ALP with the values of –20.7 ± 1.3% and –46.6 ± 2.1%, respectively. Moreover, the binding sites and modes of small-molecule compounds to ALP were investigated by molecular docking, while a new substrate competitor with theoretically good inhibitory activity against ALP was designed by scaffold hopping. Finally, the accuracy of the PGM method for enzyme activity detection was assessed by detecting ALP from milk samples, and the recovery ranged from 87.7% to 116.9%. These results indicate that it is feasible to evaluate enzyme activity and the inhibitory activity of small-molecule compounds and CS extracts on ALP using a PGM based on ALP-mediated reaction. [ABSTRACT FROM AUTHOR]

In this study, a zirconium terephthalate metal‐organic framework‐coated magnetic nanoparticle (UiO‐66@PA@PEI@Fe3O4) was synthesized for the extraction of berberine prior to high‐performance liquid chromatography analysis. The phytic acid, which could be grafted onto the magnetic nanoparticle through electrostatic interaction with the abundant amino groups of polyethylenimine, possesses outstanding metal ion coordination ability for the immobilization of metal‐organic frameworks UiO‐66. The physicochemical properties of the obtained nanoparticle were thoroughly investigated by a series of characterization techniques. Then, the factors that will affect the extraction efficiency and recovery of berberine were investigated. Results indicated that the material had good stability and reusability, and high adsorption capacity (50.01 mg/g) to berberine through single‐layer adsorption. In addition, a molecular docking study indicated that the interactions between the material and berberine were mainly π‐π stacking and hydrophobic interaction. Finally, the material was successfully applied to the extraction of berberine in Rhizoma Coptidis and Cortex Phellodendri extracts with the recoveries of 76.1% and 71.6%, respectively. [ABSTRACT FROM AUTHOR]

In this study, thrombin inhibitors in tea were characterized by combining thrombin inhibition assay of tea extracts with ultra high performance liquid chromatography–mass spectrometry based multivariate statistical analysis. The inhibitory activity on thrombin for ten tea samples were tested in vitro. Then, upon collecting and processing liquid chromatography‐mass spectrometry data, combined with the results of activity assays, principal component analysis, and orthogonal partial least squares discriminant analysis were applied to predict discriminate differential markers. Six of twelve predicted marker compounds were tentatively identified. Among them, epigallocatechin 3‐O‐gallate, epicatechin gallate, epigallocatechin and gallocatechin 3‐O‐gallate showed good inhibitory activity on thrombin with IC50 values of 5.033, 6.573, 6.704 and 6.842 mM, respectively. Moreover, molecular docking results indicated that these four active compounds could insert into the catalytic activity pocket of thrombin and the residue GLU192 may be their binding site. [ABSTRACT FROM AUTHOR]

Nanomaterials with enzyme-like activity have been widely used in the construction of colorimetric and fluorescence sensors due to their advantages of cost-effectiveness, high stability, good biocompatibility, and ease of modification. Furthermore, the colorimetric and fluorescence sensors, which are effective approaches for detecting bioactive small-molecule compounds, have been extensively explored due to their simple operation and high sensitivity. Recent significant researches have focused on designing various sensors based on nanozymes with peroxidase- and oxidase-like activity for the colorimetric and fluorescence analysis of different analytes. In this review, recent developments (from 2018 to present) in the colorimetric and fluorescent analysis of bioactive small-molecule compounds based on the enzyme-like activity of nanomaterials were summarized. In addition, the challenges and design strategies in developing colorimetric and fluorescent assays with high performance and specific sensing were discussed. • Colorimetric and fluorescent analysis of bioactive small-molecule compounds are reviewed. • Nanomaterials with POD- and OXD-like activities are commonly used in the detections. • Strategy in developing high performance colorimetric and fluorescent assays are discussed. [ABSTRACT FROM AUTHOR]

• Summarize the applications of magnetic solid-phase extraction in phytochemical analysis. • Introduce different preparation methods for the functionalized magnetic nanoparticles. • Discuss the adsorption mechanism and performance of the material in the extraction Sample preparation such as isolation and pre-concentration is a crucial step for the phytochemical analysis. Magnetic solid-phase extraction (MSPE) has received considerable attention, mainly due to its phase separation more conveniently by facile magnetic decantation as compared to traditional SPE. This review focused on the recent applications of MSPE in sample preparation for the analysis of phytochemical compounds in plants, biological samples and Chinese herbal preparations. In addition, the enzymes immobilized on the magnetic materials and used for the biospecific extraction of enzyme inhibitors were also discussed. The information summarized in this article may provide a reference to the further applications of MSPE in phytochemical analysis. [ABSTRACT FROM AUTHOR]