Pauling-Type Adsorption of O2 Induced by Heteroatom Doped ZnIn2 S4 for Boosted Solar-Driven H2 O2 Production.

Breaking the trade-off between activity and selectivity has perennially been a formidable endeavor in the field of hydrogen peroxide (H2 O2 ) photosynthesis, especially the side-on configuration of oxygen (O2 ) on the catalyst surface will cause the cleavage of O-O bonds, which drastically hinders the H2 O2 production performance. Herein, we present an atomically heteroatom P doped ZnIn2 S4 catalyst with tunable oxygen adsorption configuration to accelerate the ORR kinetics essential for solar-driven H2 O2 production. Indeed, the spectroscopy characterizations (such as EXAFS and in situ FTIR) and DFT calculations reveal that heteroatom P doped ZnIn2 S4 at substitutional and interstitial sites, which not only optimizes the coordination environment of Zn active sites, but also facilitates electron transfer to the Zn sites and improves charge density, avoiding the breakage of O-O bonds and reducing the energy barriers to H2 O2 production. As a result, the oxygen adsorption configuration is regulated from side-on (Yeager-type) to end-on (Pauling-type), resulting in the accelerated ORR kinetics from 874.94 to 2107.66 µmol g-1 h-1 . This finding offers a new avenue toward strategic tailoring oxygen adsorption configuration by the rational design of doped photocatalyst.

Mixed-Solvent-Mediated Strategy for Enhancing Light Absorption of Polydopamine and Adhesion Persistence of Dopamine Solutions.

Mussel-inspired polydopamine (PDA) and its derivative materials have exhibited a huge potential as a facile and versatile route to fabricate multifunctional coatings on virtually any substrate surface. However, their performance and applicability are frequently obstructed by limited optical absorption in visible regions of PDA and poor surface adhesion persistence of dopamine solutions. Herein, we report a facile strategy to improve these problems by rationally regulating the dopamine polymerization pathway through mixed-solvent-mediated periodate oxidation of dopamine. The spectral analysis, ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry, and density functional theory simulations systematically demonstrate that the mixed-solvent reaction systems can effectively accelerate the periodate-induced formation of cyclized moieties in the PDA microstructure and inhibit their further oxidative cleavage, thus contributing to narrowing the inherent energy band gap of PDA and improving the long-lasting surface deposition performance of aged dopamine solutions. Moreover, the newly constructed cyclized species-rich PDA coatings have excellent surface uniformity and significantly enhanced chemical stability. Benefiting from these fascinating properties, they have been further used for permanent dyeing of natural gray hair with remarkably improved blackening effect and excellent practicability, which exhibited their promising prospect in real-world applications.

Rapid Profiling of Metabolites Combined with Network Pharmacology to Explore the Potential Mechanism of Sanguisorba officinalis L. against Thrombocytopenia.

Sanguisorba officinalis L. (SO), a well-known herbal medicine, has been proven to show effect against thrombocytopenia. However, metabolites of SO in vivo are still unclear, and the underlying mechanism of SO against thrombocytopenia from the aspect of metabolites have not been well elucidated. In this study, an improved analytical method combined with UHPLC-QTOF MS and a molecular network was developed for the rapid characterization of metabolites in vivo based on fragmentation patterns. Then, network pharmacology (NP) was used to elucidate the potential mechanism of SO against thrombocytopenia. As a result, a total of 1678 exogenous metabolites were detected in urine, feces, plasma, and bone marrow, in which 104 metabolites were tentatively characterized. These characterized metabolites that originated from plasma, urine, and feces were then imported to the NP analysis. The results showed that the metabolites from plasma, urine, and feces could be responsible for the pharmacological activity against thrombocytopenia by regulating the PI3K-Akt, MAPK, JAK-STAT, VEGF, chemokine, actin cytoskeleton, HIF-1, and pluripotency of stem cells. This study provides a rapid method for metabolite characterization and a new perspective of underlying mechanism study from the aspect of active metabolites in vivo.

Molecularly imprinted polymers based on magnetic metal-organic frameworks for surface-assisted laser desorption/ionization time-of-flight mass spectrometry analysis and simultaneous luteolin enrichment.

UiO-66(NH2), a metal-organic framework, exhibits excellent UV absorption and energy transfer performance and can be used as a substrate for surface-assisted laser desorption/ionization (SALDI) analysis of small molecules. Molecularly imprinted polymers (MIPs) exhibit outstanding selectivity toward certain targets. The complexes of UiO-66(NH2) and MIPs can be applied as both an adsorbent and substrate for SALDI-time-of-flight mass spectrometry (SALDI-TOF MS) analysis of small molecules. Herein, magnetic UiO-66(NH2)-molecularly imprinted polymers (MUMIPs) were prepared for the selective enrichment and detection of luteolin via SALDI-TOF MS. The amino group on UiO-66(NH2) were used as functional monomer to prepare MIPs that interact with luteolin via hydrogen bonding. The surface functional monomer can effectively control the coating thickness of the MIPs to avoid embedding template molecules and enhance adsorption performance. In addition, Fe3O4 particles were introduced for rapid magnetic separation. The physicochemical properties of the MUMIPs were characterized via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, vibrating sample magnetometry, Brunauer-Emmett-Teller analysis, and X-ray photoelectron spectroscopy. Adsorption experiments and selectivity studies indicated that MUMIPs exhibited good adsorption capacity, fast adsorption rates, and excellent luteolin selectivity. MUMIPs are efficient substrates for the SALDI analysis of luteolin and its structural analogs. In addition, the MUMIPs-SALDI-TOF MS method successfully detected luteolin in rat plasma and urine after administration of oral Chrysanthemum morifolium Ramat extracts. This method possessed high sensitivity with a limit of detection of 0.5 ng/mL. The traditional precipitation method combined with high-performance liquid chromatography-mass spectrometry was also used to analyze luteolin in biological samples. Compared with the traditional method, the novel MUMIP-SALDI-TOF MS method can more effectively detect the target compounds in complex samples. Ultimately, the MUMIP-SALDI-TOF MS method was applied to detect luteolin and its metabolites in rat liver after oral luteolin treatment. Three luteolin metabolites (apigenin, chrysoeriol, and diosmetin) were analyzed using the newly developed MUMIP-SALDI-TOF MS method.

Preparation of sulphuric acid-mediated N,S-codoped red emissive carbon dots: Applications in food dyes detection, solid-state luminescence and cell imaging.

As diseases such as cardiovascular disease and cancer caused by food problems are more and more frequent, food safety has received great attention. Among them, the safety problem caused by food dyes is more prominent. Thus, it is of great value to develop sensitive detection methods for food dyes. In present study, sulphuric acid-mediated N,S-codoped red emissive carbon dots (namely as R-CDs) had been manufactured by using N-phenyl-o-phenylenediamine as precursor, sulfuric acid as additive for the first time. The structural and fluorescence properties of R-CDs had been systematically studied. The results demonstrated that R-CDs showed uniform spherical morphology and had a graphite-like structure, for which the average diameters size was 5.05 nm. Due to the various functional groups such as hydroxyl, pyridinic N, pyrrolic N and -C-SO4, R-CDs emitted bright red fluorescence. Importantly, because of the interactions between the functional groups of R-CDs with the selected food dyes, three dyes including amaranth, brilliant blue FCF and methylene blue can sensitively quench the fluorescence of R-CDs through IFE and static quenching effects. The linearity ranges of them were separately detected as 0.20 µM -20 µM, 10 nM-1 µM and 60 nM-8 µM. The limits of detection (LODs) of them were 70 nM, 4 nM and 20 nM, respectively. Further, R-CDs was successfully applied to the sensitive detection of three dyes from various food samples. To maximize the fluorescence properties of R-CDs, a R-CDs/PVA composite gel was fabricated to make R-CDs fluoresce in solid state condition. The potential of R-CDs/PVA composite gel for preliminary visualization analysis of three dyes was studied. Finally, ascribed to the low toxicity and good biocompatibility, the potential of R-CDs as probe for cell imaging was explored preliminarily.

Magnetic porous cellulose surface-imprinted polymers synthetized with assistance of deep eutectic solvent for specific recognition and purification of bisphenols.

Magnetic porous cellulose molecularly imprinted polymers-based bisphenols have been developed using Fe3O4 as the magnetic material, a deep eutectic solvent as the assisted solvent, and N-isopropylacrylamide as the functional monomer. The resulting magnetic porous cellulose molecularly imprinted polymers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometry, thermal gravimetric analysis, and Brunauer-Emmett-Teller analysis. Moreover, the adsorption properties of the magnetic porous cellulose molecularly imprinted polymers toward bisphenol A, bisphenol F, and bisphenol AF were investigated using static, dynamic, and selective adsorption experiments. The introduction of porous cellulose materials significantly improves the capabilities of the material. The adsorption capacity, mass transfer efficiency, and selectivity of the magnetic porous cellulose molecularly imprinted polymers toward bisphenol A were 5.9, 4.0, and 4.4 times those of traditional molecularly imprinted polymers. Moreover, the adsorption stability of the magnetic porous cellulose molecularly imprinted polymers was investigated under different temperature and pH conditions. The adsorption characteristics of the magnetic porous cellulose molecularly imprinted polymers toward the target molecules were investigated using adsorption isotherm, kinetic, and thermodynamic models. Hydrogen bonding is the main interaction formed between the magnetic porous cellulose molecularly imprinted polymers and the target molecules. Magnetic porous cellulose molecularly imprinted polymers have great application value with excellent stability and reusability. Finally, the combination of the magnetic porous cellulose molecularly imprinted polymers and high-performance liquid chromatography or ultra-performance liquid chromatography-mass spectrometry was successfully used for the purification and detection of bisphenols in milk (1.349 ng/mL bisphenol F and 3.014 ng/mL bisphenol AF), canned fruits (1129 ng/mL bisphenol A, 10.11 ng/mL bisphenol F, and 91.87 ng/mL bisphenol AF), and fish (11.91 ng/mL bisphenol AF) samples. Furthermore, the magnetic porous cellulose molecularly imprinted polymer method is more selective, sensitive, and accurate than the traditional precipitation method.

Kir2.1-mediated membrane potential promotes nutrient acquisition and inflammation through regulation of nutrient transporters.

Immunometabolism contributes to inflammation, but how activated macrophages acquire extracellular nutrients to fuel inflammation is largely unknown. Here, we show that the plasma membrane potential (Vm) of macrophages mediated by Kir2.1, an inwardly-rectifying K+ channel, is an important determinant of nutrient acquisition and subsequent metabolic reprogramming promoting inflammation. In the absence of Kir2.1 activity, depolarized macrophage Vm lead to a caloric restriction state by limiting nutrient uptake and concomitant adaptations in nutrient conservation inducing autophagy, AMPK (Adenosine 5'-monophosphate-activated protein kinase), and GCN2 (General control nonderepressible 2), which subsequently depletes epigenetic substrates feeding histone methylation at loci of a cluster of metabolism-responsive inflammatory genes, thereby suppressing their transcription. Kir2.1-mediated Vm supports nutrient uptake by facilitating cell-surface retention of nutrient transporters such as 4F2hc and GLUT1 by its modulation of plasma membrane phospholipid dynamics. Pharmacological targeting of Kir2.1 alleviated inflammation triggered by LPS or bacterial infection in a sepsis model and sterile inflammation in human samples. These findings identify an ionic control of macrophage activation and advance our understanding of the immunomodulatory properties of Vm that links nutrient inputs to inflammatory diseases.

Chemical characterization and DPP-IV inhibitory activity evaluation of tripeptides from Gynura divaricata (L.) DC.

ETHNOPHARMACOLOGICAL RELEVANCE: Gynura divaricata (L.) DC. (GD), a herbal medicine, has been used for the prevention and treatment of hyperglycemia in China. However, hypoglycemic ingredients within GD have not yet been well studied. AIM OF THE STUDY: The aim of this study was to explore undiscovered compounds with dipeptidyl peptidase IV (DPP-IV) inhibitory activity within GD. MATERIALS AND METHODS: A four-step strategy was developed to explore undiscovered DPP-IV inhibitors within GD. First, the components were preliminarily characterized using UHPLC-HRMS combined with a library search. Second, preliminarily characterized compounds were searched for potential bioactivity. Third, a mixture of these preliminarily characterized compounds was isolated and thoroughly characterized based on fragmentation patterns associated with molecular networking. Fourth, the activities of these compounds were verified using DPP-IV inhibitory assay and molecular docking. RESULTS: Diprotin A, a tripeptide inhibitor against DPP-IV, was identified. Thereafter, a mixture of twenty-five diprotin A analogs was isolated and characterized, which exhibited IC50 of 0.40 mg/mL for DPP-IV. Molecular docking results also confirmed the interactions between the tripeptide analogs and DPP-IV mainly via H-bonds and hydrophobic interactions. CONCLUSIONS: This is the first report of DPP-IV inhibitors within GD. These findings demonstrate that the extract of GD might be beneficial for the treatment of type 2 diabetes mellitus, and is expected to promote further development and utilization of GD in herbal medicine.

Comprehensive profiling of Sanguisorba officinalis using offline two-dimensional mixed-mode liquid chromatography × reversed-phase liquid chromatography, tandem high-resolution mass spectrometry, and molecular network.

The profiling of natural products is important in modern biological sciences and new drug development. However, the separation and characterization of complex herbal extracts are significantly challenging for researchers in the biochemical field. Herein, an offline two-dimensional mixed-mode liquid chromatography × reversed-phase liquid chromatography system is developed. Our system exhibits high orthogonality and is composed of a newly prepared stationary phase in the first dimension and a traditional C18 phase in the second dimension, and is operated in combination with a high-resolution mass spectrometry and molecular network. Sanguisorba officinalis L. is studied using the proposed method owing to its bioactivity. With the aid of orthogonal separation, the ionization of the individual components is improved. The number of detected compounds and separated peaks are significantly increased when one-dimensional liquid chromatography is upgraded to two-dimensional liquid chromatography. In addition, 270 compounds (127 of which are tentatively characterized as new compounds, and further confirmation is needed) are successfully characterized based on their fragmentation patterns under the guidance of molecular network, while only 95 compounds are characterized using one-dimensional liquid chromatography and high-resolution mass spectrometry. The results indicate that the developed offline two-dimensional mixed-mode liquid chromatography × reversed-phase liquid chromatography, tandem high-resolution mass spectrometry, and molecular network method are effective for profiling complex samples.

Epithelial Gasdermin D shapes the host-microbial interface by driving mucus layer formation.

Goblet cells and their main secretory product, mucus, play crucial roles in orchestrating the colonic host-microbe interactions that help maintain gut homeostasis. However, the precise intracellular machinery underlying this goblet cell-induced mucus secretion remains poorly understood. Gasdermin D (GSDMD) is a recently identified pore-forming effector protein that causes pyroptosis, a lytic proinflammatory type of cell death occurring during various pathophysiological conditions. Here, we reveal an unexpected function of GSDMD in goblet cell mucin secretion and mucus layer formation. Specific deletion of Gsdmd in intestinal epithelial cells (ΔIEC) led to abrogated mucus secretion with a concomitant loss of the mucus layer. This impaired colonic mucus layer in GsdmdΔIEC mice featured a disturbed host-microbial interface and inefficient clearance of enteric pathogens from the mucosal surface. Mechanistically, stimulation of goblet cells activates caspases to process GSDMD via reactive oxygen species production; in turn, this activated GSDMD drives mucin secretion through calcium ion-dependent scinderin-mediated cortical F-actin disassembly, which is a key step in granule exocytosis. This study links epithelial GSDMD to the secretory granule exocytotic pathway and highlights its physiological nonpyroptotic role in shaping mucosal homeostasis in the gut.

Sustainable and Green Synthesis of Waste-Biomass-Derived Carbon Dots for Parallel and Semi-Quantitative Visual Detection of Cr(VI) and Fe3.

Carbon dot (CD)-based multi-mode sensing has drawn much attention owing to its wider application range and higher availability compared with single-mode sensing. Herein, a simple and green methodology to construct a CD-based dual-mode fluorescent sensor from the waste biomass of flowers of wintersweet (FW-CDs) for parallel and semi-quantitative visual detection of Cr(VI) and Fe3+ was firstly reported. The FW-CD fluorescent probe had a high sensitivity to Cr(VI) and Fe3+ with wide ranges of linearity from 0.1 to 60 µM and 0.05 to 100 µM along with low detection limits (LOD) of 0.07 µM and 0.15 µM, respectively. Accordingly, the FW-CD-based dual-mode sensor had an excellent parallel sensing capacity toward Cr(VI) and Fe3+ with high selectivity and strong anti-interference capability by co-using dual-functional integration and dual-masking strategies. The developed parallel sensing platform was successfully applied to Cr(VI) and Fe3+ quantitative detection in real samples with high precision and good recovery. More importantly, a novel FW-CD-based fluorescent hydrogel sensor was fabricated and first applied in the parallel and semi-quantitative visual detection of Cr(VI) and ferrous ions in industrial effluent and iron supplements, further demonstrating the significant advantage of parallel and visual sensing strategies.

Ubiquitination of NLRP3 by gp78/Insig-1 restrains NLRP3 inflammasome activation.

The NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome plays a pivotal role in defending the host against infection as well as sterile inflammation. Activation of the NLRP3 inflammasome is critically regulated by a de-ubiquitination mechanism, but little is known about how ubiquitination restrains NLRP3 activity. Here, we showed that the membrane-bound E3 ubiquitin ligase gp78 mediated mixed ubiquitination of NLRP3, which inhibited NLRP3 inflammasome activation by suppressing the oligomerization and subcellular translocation of NLRP3. In addition, the endoplasmic reticulum membrane protein insulin-induced gene 1 (Insig-1) was required for this gp78-NLRP3 interaction and gp78-mediated NLRP3 ubiquitination. gp78 or Insig-1 deficiency in myeloid cells led to exacerbated NLRP3 inflammasome-dependent inflammation in vivo, including lipopolysaccharide-induced systemic inflammation and alum-induced peritonitis. Taken together, our study identifies gp78-mediated NLRP3 ubiquitination as a regulatory mechanism that restrains inflammasome activation and highlights NLRP3 ubiquitination as a potential therapeutic target for inflammatory diseases.

Photocatalytic H2O2 production and removal of Cr (VI) via a novel Lu3NbO7: Yb, Ho/CQDs/AgInS2/In2S3 heterostructure with broad spectral response.

The low-usage of solar energy and the sluggish separation efficiency of the photogenerated electrons/holes pairs are the obstacles in the practical application of photocatalysts. The integration of upconversion and Z-scheme heterojunction is expected to break the barriers to achieve the efficient charge separation and broaden near-infrared light absorption. Herein, an effective indirect Z scheme AgInS2/In2S3 heterostructure with carbon quantum dots (CQDs, as the electron conduction medium) and Lu3NbO7:Yb, Ho (as upconversion function) has been successfully synthesized. Consequently, the Lu3NbO7: Yb, Ho/CQDs/AgInS2/In2S3 heterostructure exhibited superior photocatalytic activities for Cr(VI) reduction and H2O2 production, reducing 99.9% of Cr(VI)(20 ppm, 15 min) and 78.5% of Cr(VI) (40 ppm, 30 min) with visible light irradiation as well as 94.0% of Cr(VI) (20 ppm, 39 min) under NIR light irradiation. Simultaneously, the heterostructure could generate 902.9 µM H2O2 for 5 h under visible light irradiation. The intensive photocatalytic properties could primarily be attributed to the boosted light absorption capacity, the improved solar-to-energy conversion by the remarkable upconversion capacity of Lu3NbO7: Yb, Ho/CQDs and the faster charge transfer through a Z-schematic pathway. This work is anticipated to open a novel "window" for designing the efficient photocatalysts by coupling of Lu3NbO7: Yb, Ho and CQDs.

AKT controls NLRP3 inflammasome activation by inducing DDX3X phosphorylation.

The NLRP3 inflammasome, a critical component of the innate immune system, induces caspase-1 activation and interleukin-1ß maturation and drives cell fate toward pyroptosis. However, the mechanism of NLRP3 inflammasome activation still remains elusive. Here we provide evidence that AKT regulates NLRP3 inflammasome activation. Upon NLRP3 activation, AKT activity is inhibited by second stimulus-induced reactive oxygen species. In contrast, AKT activation leads to NLRP3 inhibition and improved mitochondrial fitness. Mechanistically, AKT induces the phosphorylation of the DDX3X (DEAD-box helicase 3, X-linked), a recently identified NLRP3 inflammasome component, and impairs the interaction between DDX3X and NLRP3. Furthermore, an AKT agonist reduces NLRP3-dependent inflammation in two in vivo models of LPS-induced sepsis and Alum-induced peritonitis. Altogether, our study highlights an important role of AKT in controlling NLRP3 inflammasome activation.

Highly Crystalline Covalent Organic Frameworks Act as a Dual-Functional Fluorescent-Sensing Platform for Myricetin and Water, and Adsorbents for Myricetin.

Selective detection of active ingredients in complex samples has always been a crucial challenge because there are many disturbing compounds, especially structural analogues that interfere with the detection. In this work, a fluorescent covalent organic framework (named COF-TD), which can be used for the selective fluorescence detection and enrichment of myricetin from complex samples, was reported for the first time. The highly crystalline COF-TD with bright blue fluorescence was formed through a solution polymerization method by the condensation reaction between 4,4',4″-(1,3,5-triazine-2,4,6-triyl)trianiline and 2,5-dihydroxy-1,4-benzenedicarboxaldehyde. Due to spatial size selectivity, multisites hydrogen bonding, and π-π interaction, myricetin can quench the fluorescence of COF-TD with an inner filter effect (IFE) and static quenching mechanisms as well as can be enriched on COF-TD. Myricetin can observably eliminate the interference of other compounds and selectively quench the fluorescence of COF-TD with a limit of detection (LOD) of 0.30 µg·mL-1. The high adsorption ability of COF-TD (Q = 124.6 mg·g-1) to myricetin was also obtained. Finally, a sensing platform based on COF-TD for myricetin was successfully developed and applied for the detection of myricetin from vine teas. In addition, COF-TD also showed good water sensing ability and could be used effectively to detect water content in organic solvent (1-18% water in acetone, 0.5-5% water in acetonitrile, 1-4.5% water in ethyl acetate, v/v). To the best of our knowledge, this is the first report where COF-TD was used to detect water in a relatively wide concentration range. In all, this work provided dual-functional fluorescent COFs with the properties of an adsorbent, opening up new methodologies for the simple, selective, and enrichment detection method for myricetin.

Polydopamine-Assisted Rapid One-Step Immobilization of L-Arginine in Capillary as Immobilized Chiral Ligands for Enantioseparation of Dansyl Amino Acids by Chiral Ligand Exchange Capillary Electrochromatography.

Herein, a novel L-arginine (L-Arg)-modified polydopamine (PDA)-coated capillary (PDA/L-Arg@capillary) was firstly fabricated via the basic amino-acid-induced PDA co-deposition strategy and employed to constitute a new chiral ligand exchange capillary electrochromatography (CLE-CEC) method for the high-performance enantioseparation of D,L-amino acids (D,L-AAs) with L-Arg as the immobilized chiral ligand coordinating with the central metal ion Zn(II) as running buffer. Assisted by hydrothermal treatment, the robust immobilization of L-Arg on the capillary inner wall could be facilely achieved within 1 h, prominently improving the synthesis efficiency and simplifying the preparation procedure. The successful preparation of PDA/L-Arg coatings in the capillary was systematically characterized and confirmed using several methods. In comparison with bare and PDA-functionalized capillaries, the enantioseparation capability of the presented CLE-CEC system was significantly enhanced. Eight D,L-AAs were completely separated and three pairs were partially separated under the optimal conditions. The prepared PDA/L-Arg@capillary showed good repeatability and stability. The potential mechanism of the greatly enhanced enantioseparation performance obtained by PDA/L-Arg@capillary was also explored. Moreover, the proposed method was further utilized for studying the enzyme kinetics of L-glutamic dehydrogenase, exhibiting its promising prospects in enzyme assays and other related applications.

Nonlinear behavior in preparative liquid chromatography: A method-development case study for hydroxytyrosol purification.

Preparative liquid chromatography has become an important purification method owing to its advantages of high separation efficiency, good reproducibility, and low solvent consumption. Because overloading in preparative liquid chromatography must be performed to increase the throughput in a cycle, nonlinear chromatographic behavior is observed. Therefore, it is crucial to carefully study nonlinear chromatography for the purification of a given product, which facilitates the efficient optimization of the purification parameters. In this work, a method for the development of a purification method using preparative liquid chromatography based on nonlinear chromatography is proposed. Hydroxytyrosol was selected as the subject for method demonstration. Using methanol and ethanol as organic modifiers, the optimum flow rate was determined on three commercial columns entitled C8 TDE, C18 ME, and C18 TDE, respectively. The curves were fitted with the van Deemter equation, with thorough analysis of the A, B, and C terms. Adsorption isotherms were subsequently studied to explore the distribution of solutes between the stationary and mobile phases at equilibrium. C18 TDE, 5 vol% ethanol-water, and 0.2 mL/min were selected as the optimal separation material, elution solvent, and flow rate, respectively. Purification of hydroxytyrosol was tentatively confirmed on a C18 TDE column with 1.6% sample loading, 90.98% recovery, and 98.01% purity.

Fabrication of covalent organic frameworks and its selective extraction of fluoronitrobenzenes from environmental samples.

In this study, porous covalent organic frameworks (COFs, named as COFs-SWMU) were synthesized for the first time via a facile approach by using 4,4',4''-methylidynetri-anilin and 2,5-dihydroxy-1,4-benzenedicarboxaldehyde as precursors under ambient temperature. The COFs-SWMU were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, thermogravimetric analysis, etc. The COFs-SWMU exhibited a relatively high specific surface area and desirable thermal stability. The adsorption performance of COFs-SWMU towards fluoronitrobenzenes (FNBs, including 1-fluoro-2-nitrobenzene, 1-fluoro-3-nitrobenzene, 1-fluoro-4-nitrobenzene, 2,4-difluoronitrobenzene, 3,4-difluoronitrobenzene, and 3,4-dinitrofluorobenzene) was investigated on the basis of adsorption capacity and partition coefficient (PC). The adsorption kinetics and isotherm of COFs-SWMU for FNBs were studied in detail. Further, a simple, fast and sensitive method which combined COFs-SWMU based extraction with high-performance liquid chromatography-diode array detection, was proposed for the analysis of FNBs in environmental samples. Desirable linearity (R2>0.9998) in the range of 0.1-100 µg•mL-1, low limits of detection (LODs; 0.1‒0.15 µg•mL‒1), low limits of quantitation (LOQs; 0.28‒0.40 µg•mL‒1), and desirable precision (RSDs, 0.24-2.83% for intraday and 1.13-6.92% for interday) are obtained. Finally, the COFs-SWMU were applied to the effective extraction of FNBs from environmental samples, and desirable recovery results were obtained.

Preparation of an aspartame and N-isopropyl acrylamide copolymer functionalized stationary phase with multi-mode and chiral separation abilities.

A novel multi-mode and chiral separation stationary phase co-modified with copolymer composed of N-isopropyl acrylamide (NIPAM) and aspartame was synthesized by atom transfer radical polymerization (ATRP) reaction. The synthetic material was evaluated using thermogravimetric analysis (TGA), Fourier transform infrared spectrometry (FT-IR) and elemental analysis (EA). Analytes including hydrophobic, hydrophilic, alkaline and acidic compounds were separated well using the prepared stationary phase named Sil-PPAM-NIPAM. Besides, the separation of chiral compounds proved that the developed column also has the potential of chiral separation ability. In summary, the prepared column possesses excellent hydrophilic interaction, ion exchange, reversed-phase and chiral separation modes during the separation of complex and chiral compounds.

Nanoscale Hierarchically Micro- and Mesoporous Metal-Organic Frameworks for High-Resolution and High-Efficiency Capillary Electrochromatographic Separation.

Metal-organic frameworks (MOFs) have been widely applied in a variety of fields. However, most of the developed MOFs are micrometer scale in crystal size and contain only micropores, which will limit the mass transport and diffusion of various analytes into their internal interaction sites, severely restricting the potential of MOFs in separation science. Herein, nanoscale hierarchically porous MOFs (NHP-MOFs) were first explored as a novel MOF-based stationary phase with excellent mass transfer performance and abundant accessible interaction sites for high-performance chromatographic separation. As a proof-of-concept demonstration, the nanoscale hierarchically micro- and mesoporous UiO-66 (NHP-UiO-66) was firmly immobilized on the capillary inner surface and utilized as the porous stationary phase for high-resolution and high-efficiency electrochromatographic separation. A wide range of low-, medium-, and high-molecular-weight analytes, including substituted benzenes, chlorobenzenes, polycyclic aromatic hydrocarbons, nucleosides, polypeptides, and proteins were all separated well on a NHP-UiO-66-coated column with excellent resolution and repeatability, exhibiting significantly improved column efficiency and separation ability compared to those of a microporous UiO-66-modified column. The maximum column efficiencies for all the six kinds of analytes reached up to 1.2 × 105 plates/m, and the relative standard deviations of the migration times of substituted benzenes for intraday, interday, and column-to-column were all lower than 5.8%. These results reveal that NHP-MOFs can effectively combine the advantages of the high specific surface area of microporous MOFs and the excellent mass transfer performance and abundant accessible interaction sites of NHP materials, possessing great prospect for high-performance chromatographic separation.