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3-(2-Aminoethylamino)propyltriethoxysilane and carboxyethylsilanetriol sodium salt were grafted on silica-coated Fe 3 O 4 nanoparticles via sol-gel process to prepare novel amine- and carboxyl-bifunctionalized magnetic nanocomposites (SMNPs-(NH 2 + COOH)). After well characterized, this doubly functionalized material was used as magnetic solid-phase extraction (MSPE) adsorbent to separate and enrich inorganic chromium species followed by inductively coupled plasma-mass spectrometry detection. The optimization of MSPE operation parameters including pH was conducted. It is reasonably elucidated that the adsorption mechanisms of zwitterionic SMNPs-(NH 2 + COOH) towards chromium species are electrostatic and/or coordination interactions. Cr(VI) and Cr(III) can be adsorbed around pH 3.0 and around 10.0 respectively with strong anti-interference ability not only from other co-existing ions but also from the two labile species each other, and eluted by dilute nitric acid solution. With a 15-fold enrichment factor, the limits of detection of Cr(VI) and Cr(III) were 0.008 and 0.009 μg L -1 , respectively, profiting from the maximum adsorption capacities of 7.52 and 6.11 mg g -1 . The just one magnetic extraction matrix based speciation scheme possesses excellent convenience and friendliness to Cr(VI) and Cr(III) without any oxidation or reduction prior to capture of these two species. This protocol has been successfully applied to the speciation analysis of inorganic chromium in real-world environmental water samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: The convenient preparation and application of functionalized organic-inorganic hybrid monolithic materials have obtained substantial interest in the pretreatment of complex samples by solid-phase extraction (SPE). Compared to the in-tube solid-phase microextraction in fused-silica capillaries, micro SPE in plastic pipette tips have fascinating merits for the easily operated enrichment of trace target analytes from biological samples. However, the poor compatibility of organic-inorganic hybrid monoliths with plastics leads to the rare appearance of commercial hybrid monolithic pipette tips (HMPTs). Therefore, how to synthesize the organic-inorganic hybrid monolithic materials with better extraction performance in plastic pipette tips becomes a challenge., Results: We develop a facile and cheap strategy to immobilize organic-inorganic hybrid monoliths in pipette tips. Melamine sponge was employed as the supporting skeleton to in situ assemble amine- and thiol-bifunctionalized hybrid monolithic material via "one pot" in a pipette tip, and gold nanoparticles (GNPs) and thiol-modified aptamer against human α-thrombin were sequentially attached to the hybrid monolith within the HMPTs. The average coverage density of the aptamer with GNPs as an intermediary reached as high as 818.5 pmol μL -1 . The enriched thrombin concentration was determined by a sensitive enzymatic chromogenic assay with the limit of detection of 2 nM. The extraction recovery of thrombin at 10 nM in human serum was 86.1 % with a relative standard deviation of 6.1 %. This proposed protocol has been applied to the enrichment and determination of thrombin in real serum sample with strong anti-interference ability, low limit of detection and high recovery., Significance: The amine- and thiol-bifunctionalized HMPTs prepared with sponge as the skeleton frame provided a novel substrate material to decorate aptamers for efficient enrichment of proteins. This enlightens us that we can take advantage of the tunability of sponge assisted HMPTs to produce and tailor a variety of micro SPE pipette tips for broader applications on the analysis of trace targets in complex biological, clinic and environmental samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

G-quadruplexes (G4s) play an important role in a variety of biological processes and have extensive application prospects. Due to the significance of G4s in physiology and biosensing, studies on G4s have attracted much attention, stimulating the development or improvement of methods for G4 structures and polymorphism analysis. In this work, ionic liquids (ILs) were involved as mobile phase additives in reversed-phase high performance liquid chromatography (RP-HPLC) to analyse G4s with various conformations for the first time. How ILs affected the retention behaviors of G4s was investigated comprehensively. It was found that the addition of ILs markedly enhanced G4 retention, along with obvious amelioration on chromatographic peak shapes and separation. The influence of pH of mobile phase and types of ILs were also included in order to acquire an in-depth understanding. It appeared that the effect of ILs on G4 retention behaviors was the result of a combination of various interactions between G4s with the hydrophobic stationary phase and with the IL-containing mobile phase, where ion pair mechanism and enhanced hydrophobic interaction dominated. The findings of this work revealed that ILs could effectively improve the separation of G4s in RP-HPLC, which was conducive to G4 structural analysis, especially for G4s polymorphism elucidation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

MXenes have received lots of attention since discovered and have been applied in various fields. In this work, Ti 3 C 2 -Fe 3 O 4 composites with exposed non-modified Ti 3 C 2 MXene nanosheets were designed and prepared by an in situ growth strategy and then applied in the enrichment of phosphopeptides. The two-dimensional composites could interact with the phosphopeptides through a metal oxide affinity chromatography mechanism provided by Ti-O and Fe-O bonds and a hydrophilic interaction chromatography mechanism by surface hydroxyl groups. This magnetic nanomaterial with a specific surface area of 66.1 m 2 ·g -1 had high sensitivity to phosphopeptides (0.5 nmol·L -1 ) and high selectivity (1:1000 of the molar ratio of β-casein to bovine serum albumin). Non-fat milk was adopted as a real sample to preliminarily examine the applicability of the Ti 3 C 2 -Fe 3 O 4 -based protocol. Subsequently, Qingkailing injection, a kind of traditional Chinese medicine injection, was introduced to further explore the suitability of the nanocomposites for phosphopeptide enrichment from more complex matrices and satisfactory results were obtained.

The abuse of enrofloxacin (ENR) in aquaculture and the lack of monitoring of other metabolites except ciprofloxacin (CIP) may lead to unknown harmful effects on human health. In this study, ENR metabolites were screened in real fish samples based on ultrahigh-performance liquid chromatography coupled with Q-Orbitrap mass spectrometry combined with Compound Discoverer software, and another metabolite deethylene-ENR besides CIP was detected and identified for the first time. Correspondingly, a method for the determination of ENR and CIP and the semi-quantitative analysis of deethylene-ENR in aquatic products was established. Method validation illustrated that excellent linearity and satisfactory recoveries of analytes were obtained. Limits of detection of ENR and CIP were both 0.1 μg kg -1 , and their limits of quantification both 1 μg kg -1 . CIP and deethylene-ENR were detected in 12 of 14 ENR-positive fish samples, so deethylene-ENR should be of concern as a possible risk candidate in aquatic products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Chlorpromazine (CPZ) is abused in animal husbandry and can be extensively metabolized in humans and animals. However, the actual monitoring mainly focuses on the parent compound but lacks attention to its metabolites. A method was developed and validated firstly for identification and determination of CPZ and its four major metabolites in animal-derived foods using ultrahigh-performance liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry in combination with QuEChERS preparation method. Satisfactory recoveries of analytes spiked in fish and pork samples ranged from 72 to 117 %, and limits of quantification were 2.0 and 1.0 μg kg -1 for fish and pork samples respectively. Moreover, through the hydrolysis experiments of CPZ, its hydrolysates, such as CPZ-sulfoxide, CPZ-N-oxide and CPZ-sulfoxide-N-oxide, were identified as potential risk compounds. The developed method has been successfully applied to the determination of CPZ and its metabolites in actual commercial samples, as well as to the screening of other CPZ-related risk compounds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The n -octanol-water partition coefficient (log P ) is an important physicochemical parameter which describes the behavior of organic compounds. In this work, the apparent n -octanol/water partition coefficients (log D ) of basic compounds were determined using ion-suppression reversed-phase liquid chromatography (IS-RPLC) on a silica-based C18 column. The quantitative structure-retention relationship (QSRR) models between log D and log k w (logarithm of retention factor corresponding to 100% aqueous fraction of mobile phase) were established at pH 7.0-10.0. It was found that log D had a poor linear correlation with log k w at pH 7.0 and pH 8.0 when strongly ionized compounds were included in the model compounds. However, the linearity of the QSRR model was significantly improved, especially at pH 7.0, when molecular structure parameters such as electrostatic charge n e and hydrogen bonding parameters A and B were introduced. External validation experiments further confirmed that the multi-parameter models could accurately predict the log D value of basic compounds not only under strong alkaline conditions, but also under weak alkaline and even neutral conditions. The log D values of basic sample compounds were predicted based on the multi-parameter QSRR models. Compared with previous work, the findings of this study extended the pH range for the determination of the log D values of basic compounds, providing an optional mild pH for IS-RPLC experiments.

Laboratories use different strategies to sample and extract atmospheric particulate matter (PM), some of which can be very complicated. Due to the absence of a standard protocol, it is difficult to compare the results of PM toxicity assessment across different laboratories. Here, we proposed a novel PM sampling and cell exposure strategy based on agar membrane. The agar membrane, prepared by a simple freeze-drying method, has a relatively flat surface and porous interior. We demonstrated that the agar membrane was a reliable substitute material for PM sampling. Then the PM on the agar membranes was directly extracted with the culture medium by vortex method, and the PM on the polytetrafluoroethylene (PTFE) filters was extracted with water by the traditional ultrasonic method for comparison. The extraction efficiency was evaluated and in vitro cytotoxicity assays were carried out to investigate the toxic effects of PM extracted with two strategies on macrophage cells. The results showed that the PM extracted from agar membranes induced higher cytotoxicity and more differentially expressed proteins. Overall, the novel PM sampling-cell exposure strategy based on the agar membrane is easy to operate, biocompatible and comparable, and has low disturbance, could be an alternative sampling and extraction method for PM toxicity assessment., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Mercapto- and amino-functionalized magnetic nanoparticles, Fe 3 O 4 @SiO 2 @MPTMS (SMNPs-MPTMS) and Fe 3 O 4 @SiO 2 @APTES (SMNPs-APTES), have been applied as magnetic solid-phase extraction (MSPE) sorbents to directly extract arsenite (As(III)) and arsenate (As(V)) respectively, followed by inductively coupled plasma-mass spectrometry (ICP-MS) detection. Various MSPE parameters were optimized including dose of magnetic adsorbent, pH of sample solution, loading and elution conditions of analytes, adsorption capacity and reusability of SMNPs-MPTMS and SMNPs-APTES for As(III) and As(V) respectively. Under the optimized MSPE conditions, this combined scheme possesses excellent selectivity and strong anti-interference ability without any oxidation or reduction prior to capture of these two species. It is found that with a 25-fold enrichment factor, the limits of detection of As(III) and As(V) were 23.5 and 10.5 ng L -1 , respectively. To verify the reliability of the proposed protocol, a certified reference material of environmental water was analyzed, and the results for inorganic arsenic species were in close agreement with the certified values. The applicability of the combination strategy for speciation analysis of inorganic arsenic was evaluated in spiked tap, river, lake and rain water samples. Good recoveries of 89%-96% and 90%-102% were achieved for As(III) and As(V), respectively, with the relative standard deviation ranges of 3.2%-8.0% and 2.5%-7.6%. Through the characterization of functionalized magnetic nanoparticles and the optimization of MSPE experiment, it is confirmed that the existence of mercapto and amino groups on SMNPs-MPTMS and SMNPs-APTES sorbents are responsible for the extraction of As(III) and As(V), respectively, via coordination and electrostatic interactions., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this work, a novel amino functionalized Cu(II) ion-imprinted organic-inorganic hybrid monolithic column (Cu(II)-IIHMC) was prepared via one-pot co-condensation and the combination of sol-gel and ion-imprinting techniques in a fused capillary. The Cu(II)-IIHMC was used as solid phase microextraction (SPME) matrix followed by inductively coupled plasma-mass spectrometry (ICP-MS) for the analysis of trace Cu(II). The prepared Cu(II)-IIHMC has good mechanical strength, stable imprinting sites and homogeneous structure of network skeleton with large flow-through pores by optimizing the synthesis process. Under the optimized conditions, the Cu(II)-IIHMC can selectively adsorb Cu(II) with the adsorption capacity of 3.13 mg g -1 . With enrichment factor of 10-fold, the calibration curve was established in the range of 0.05-50 μg L -1 with r 2 of 0.9992 and the detection limit was 0.008 μg L -1 for Cu(II). Compared with the non-imprinted hybrid monolithic column (Cu(II)-NIHMC), the Cu(II)-IIHMC possesses better selectivity, anti-interference ability and adsorption capacity. The Cu(II)-IIHMC can specifically capture the target ion in the presence of competitive ions, with the selectivity coefficients exceeding 39.4. The protocol was validated by analyzing Certified Reference Materials of standard sediment, soil and iron ore, and the results were in good agreement with certified values. Moreover, the proposed in-tube SPME procedure can not only preconcentrate trace Cu(II), but also effectively reduce the matrix effect and powerfully eliminate the interference from the main metals in real samples. Therefore, the developed SPME-ICP-MS method with facile preparation, specific selectivity, high sensitivity and efficient analysis, was applied in the determination of trace Cu(II) in environmental and mineral samples with the recoveries of 89.8-111.8% in all spiked samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Effective protein adsorption by solid matrices from complex biological samples has attracted attention for broad application in biomedical field. Immobilization of calixarenes to solid supports is an essential process for their application in protein separation and purification. Silica is the most widely used support material in calixarene immobilization. With high concentration of polymer microspheres as templates, the large pore mesoporous silica microspheres with controllable, uniform size and structure were successfully synthesized and the resulting large pore mesoporous silica microspheres were modified with water-soluble tetrasulfonate calix[4]arene of unique hollow cavity-shaped structure. The tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres (SCLX4@LPMS) were characterized by diverse analytical techniques and their protein adsorption performance were also investigated. The obtained SCLX4@LPMS gave rise to an adsorption efficiency of >90% for cytochrome c and lysozyme within a wide pH range of 3.0-10.0 and possessed remarkably high adsorption capacity of cytochrome c (363.64 mg g -1 ) and lysozyme (166.11 mg g -1 ). The retained cytochrome c and lysozyme can be readily eluted by using phosphate buffer solution containing NaCl as a stripping reagent with the recoveries of 81% and 86% after 5 times enrichment, respectively. The SCLX4@LPMS microspheres have been applied for the selective adsorption of proteins in real samples and had the application potential in protein adsorption, drug delivery, biosensors, and other biomedical fields., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Organic-inorganic hybrid monolithic columns, due to the comprehensive advantages, have been applied as promising solid-phase separation matrices for pretreatment of complex samples in biomedical and environmental analyses, however, a tremendous time and efforts are cost to optimize the preparation methods of hybrid monolithic columns with different functional groups for various target analytes. Herein, we proposed a strategy to develop basic hybrid monolithic column materials for flexible and facile post-functionalization. Three kinds of single-functionalized (amine, thiol, and carboxyl) and two kinds of bi-functionalized (amine and thiol, and amine and carboxyl) hybrid monolithic columns were immobilized with gold nanoparticles (GNPs) as intermediary bridge to construct the universal substrates. The GNPs adsorption capacities of the five hybrid monoliths were compared through qualitative characterization and quantitative analysis. Thioglycolic acid (TGA) and an aptamer against human α-thrombin were respectively used for further functionalizing the substrates to select the most suitable hybrid monolith for optional post-functionalization. It was reported for the first time that the coverage density of TGA on functionalized monolithic column modified by GNPs was 168.41 nmol μL -1 . Notably, the coverage density (2205.8 pmol μL -1 ) of the aptamer decorated on the hybrid monolithic column was significantly higher than most other similar materials in published works. After that, the aptamer functionalized hybrid monolithic column screened out was applied for the solid-phase microextraction of thrombin, which possessed excellent adsorption selectivity in interference experiment. Consequently, the developed GNPs modified amine- and thiol-bi-functionalized hybrid monolithic column is an attractive universal substrate to realize easy and efficient post-modification of separation materials for other target analytes in complex samples avoiding a lot of time and labor consumption in the optimization of process preparation., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Environmental natural organic matters (NOMs) have great effects on the physicochemical properties of engineering nanoparticles, which may impact the transport of nanoparticles across plasma membrane and the cytotoxicity. Therefore, the kinetics, uptake pathway and mass of transporting into A549 cell membrane of silver nanoparticles (AgNPs) coated with citric acid (CA), tartaric acid (TA) and fulvic acid (FA) were investigated, respectively. CA, FA and TA enhanced the colloidal stability of AgNPs in culture medium and have greatly changed the surface plasmon resonance spectrum of AgNPs due to the absorption of CA, FA and TA on surface of AgNPs. Internalizing model showed that velocity of CA-, TA- and FA-nAg transporting into A549 cell were 5.82-, 1.69- and 0.29-fold higher than those of the control group, respectively. Intracellular mass of Ag was dependent on mass of AgNPs delivered to cell from suspension, which obeyed Logistic model and was affected by NOMs that CA- and TA-nAg showed a large promotion on intracellular mass of Ag. The lipid raft/caveolae-mediated endocytosis (LME) of A549 cell uptake of AgNPs were susceptible to CA, TA and FA that uptake of CA-, TA- and FA-nAg showed lower degree of dependent on LME than that of the control (uncoated AgNPs). Actin-involved uptake pathway and macropinocytosis would have less contribution to uptake of FA-nAg. Overall, transmembrane transport of NOMs-coated AgNPs differs greatly from that of the pristine AgNPs.

A novel carboxyl-functionalized hybrid monolithic column was developed based on "thiol-ene" click reaction via "one-pot" by choosing mercaptosuccinic acid, γ-methyl methacrylate trimethoxysilane and tetramethoxysilane as reaction monomers. The design of the hybrid monolithic column was assisted by the comparison in computational simulation with existing carboxyl-functionalized materials. The characterization by scanning electron microscopy, energy dispersive X-ray spectroscopy, N 2 adsorption-desorption measurement, Fourier-transform infrared spectroscopy and elemental analysis showed that the carboxyl-functionalized material has the advantages of good permeability and high mechanical strength. Then, we used the prepared carboxyl-hybrid monolith column as solid phase microextraction adsorbent for separation of trace inorganic chromium species. Under pH 4.5, the hybrid monolith column can selectively enrich Cr(III) without adsorbing Cr(VI) and afterwards, Cr(III) can be eluted by 1.0 mol L -1 HCl. The chromium speciation separation method based on carboxyl-hybrid monolith column followed by inductively coupled plasma-mass spectrometry possessed the merits of facile preparation, low cost, simple and mild extraction condition, and sensitive detection, which has been successfully applied to the separation, enrichment and detection of inorganic chromium in environmental waters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this work, the correlations between retention behavior and lipophilicity of a large set of hydrophilic neutral and ionic analytes were studied based on three hydrophilic interaction liquid chromatography (HILIC) stationary phases, including zwitterionic, crosslinked diol and triazole stationary phases. It was found that HILIC, due to the diversity of retention mechanism, is a more complex chromatography separation mode than reversed-phase liquid chromatography (RPLC) which has been widely accepted for lipophilicity assessment. Because electrostatic interactions contributed to the overall retention of the charged solutes on all three stationary phases, ion-strength of the mobile phase kept the same during the whole experiment. After the correlations between retention factor log k and water volume fraction Φ were investigated, the mixed retention model was revealed to be more suitable for HILIC retention behavior than other single models including partitioning and adsorption model. Moreover, in order to bridge the relationship between HILIC log k and lipophilicity parameter log D, net charge n e and Abraham solvation parameter were introduced in the quantitative structure-retention relationship (QSRR) model. Although the correlation coefficients between log D and log k were still moderate, the significant improvement in correlation has made HILIC a potential choice as the complement of RPLC for log D measurement., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The preparation of an amino-functionalized hybrid monolithic column (TEOS-co-AEAPTES) via one-pot co-condensation of tetraethoxysilane (TEOS) and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AEAPTES) in a capillary is descibed. It was used as solid-phase microextraction (SPME) matrix followed by inductively coupled plasma-mass spectrometry (ICP-MS) for determination of trace metals. Under optimum conditions, the amino-functionalized SPME material can simultaneously retain Cu(II), Zn(II), Au(III), and Pb(II) with adsorption capacities of 148, 60, 81, and 64 μg m -1 , respectively. Subsequently, these four metal ions can be quantitatively eluted using 1 mol L -1 HNO 3 containing 1% thiourea. The retention mechanism of Cu(II), Zn(II), Au(III), and Pb(II) on the amino-functionalized hybrid monolith was explained as the combination of electrostatic and coordination interactions. With a 10-fold enrichment factor, the calibration curves were established in the range 0.5-100 μg L -1 with linear correlation coefficients above 0.9943 and the limits of quantitation were 0.05 μg L -1 for four target analytes. The limits of detection were 0.006, 0.012, 0.004, and 0.007 μg L -1 for Cu(II), Zn(II), Au(III), and Pb(II), respectively. The protocol was validated by analyzing Certified Reference Materials including standard sediment, soil, and nickel ore, and the results were in good agreement with their certified values. The relative standard deviations of the method were in the range 0.22-17.6%. The recoveries of the four metal ions in spiked samples were in the range 88.0-113.8%. Compared to direct ICP-MS determination, the proposed in-tube SPME procedure can effectively eliminate the interference from complex matrix, especially from those ores with very high content of main metal to improve the accuracy of analysis. Therefore the method is suitable for the simultaneous determination of ultra-trace Cu(II), Zn(II), Au(III), and Pb(II) in environmental and mineral samples. Graphical abstract The preparation of the TEOS-co-AEAPTES monolithic column and the SPME procedure of Cu(II), Zn(II), Au(III), and Pb(II).

A novel amine- and carboxyl-bifunctionalized organic-inorganic hybrid monolithic column (A&C-HMC) was synthesized via one-pot co-condensation of N-(2-aminoethyl)-3-aminopropyltriethoxysilane, carboxyethylsilanetriol sodium salt and tetramethoxysilane with cetyltrimethylammonium bromide and polyethylene glycol 6000 as binary porogens in this work. The introduction of the binary porogens controllably improved the morphology and pore structure of A&C-hybrid monolith (HM) and made the active sites of amine and carboxyl groups more prolific, compared with the monolith prepared with either of porogens. It is found that Cr(VI) and Cr(III) can be selectively adsorbed on A&C-HM under different pH ranges, and eluted by aqueous nitric acid solution completely. The A&C-HMC was used as needle-solid phase microextraction (SPME) matrix for direct separation and enrichment of inorganic chromium species coupled with inductively coupled plasma mass spectrometer without any oxidation/reduction treatment. Various parameters of SPME operation and analytical performance were investigated systematically, and the adsorption mechanism was also discussed and explained in depth. In view of the advantages of facile preparation, low cost, excellent speciation selectivity and high adsorption capacity to Cr(VI) and Cr(III), the A&C-HMC based SPME protocol is a promising alternative for non-disturbed speciation analysis of inorganic chromium in real environmental water samples., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Differences of cytotoxicity associated with exposure to different extracts of atmospheric particulate matters (PMs) are still not well characterized by in vitro toxicoproteomics. In this study, in vitro cytotoxicity assays and toxicoproteomic analyses were carried out to investigate toxic effects of PM collected using polytetrafluoroethylene (PTFE) filters extracted with acetone for PM 2.1 and water for PM 2.1 and PM 10 on A549 human lung epithelial cells. The cytotoxicity assays based on cell viability, cell apoptosis and reactive oxygen species generation indicated that PM 2.1 extracted with acetone had the highest toxicity. iTRAQ labeling and LC-MS/MS analyses indicated that the number of differentially expressed proteins in A549 cells affected by PM 2.1 extracted with acetone was noticeably higher than that of the other two groups. Hierarchical cluster analyses showed that the influences of the extracts of PM 2.1 and PM 10 using water on the proteome of A549 cells were similar, whereas significantly different from the effect of PM 2.1 extracted with acetone. Pathways analyses indicated that PM 2.1 extracted with acetone influenced the expression of proteins involved in 14 pathways including glycolysis/gluconeogenesis, pentose phosphate pathway, proteasome, etc. PM 2.1 extracted with water affected the expression of proteins involved in 3 pathways including non-homologous end-joining, ribosome and endocytosis. However, PM 10 extracted with water affected the expression of proteins involved in only spliceosome pathway. The extracts of PM using different extractants to detach PM from PTFE filters influenced the cytotoxic effects of PM and the proteome of A549 cells. Therefore, extractants should be assessed carefully before the investigations on cytotoxicity to improve the compatibility of experimental results among research teams., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The iron oxide nanoparticles (Fe 3 O 4 ) were prepared by organic molecule-assisted method in aqueous solution. The facile synthetic process of Fe 3 O 4 nanoparticles was conducted only by mixing FeCl 2 and 2-methylimidazole (2-MIM) without any additives. A possible growth mechanism of the Fe 3 O 4 nanocrystals was proposed for this mild reaction. Then, the Fe 3 O 4 nanoparticles were anchored onto graphene oxide (GO) sheets in water by ultrasound-assisted method, forming an affinity probe with strong biocompatibility. Due to the hydroxy and carboxylic groups of GO sheets, Fe 3 O 4 /GO probe exhibits excellent performance for enriching low-abundance hydrophilic peptides, while the Fe 3 O 4 nanoparticles endure the probe with specific affinity to phosphopeptides. The analytical protocol was developed for sequential enrichment of low-abundance peptides and phosphopeptides by the affinity probe. It exhibited the sequence coverage of 26% for capture of 17 low-abundance peptides from bovine serum albumin (BSA), as well as the selectivity of 1:1:100 for phosphopeptides from α-/β-casein/BSA, and low detectable concentration of 2.5 fmol and probe reusability of 5 times for capture of phosphopeptides from α-/β-casein. Consequently, the prepared Fe 3 O 4 /GO material possesses excellent feature as multifunctional affinity probe for low-abundance peptides including phosphopeptides from complex biological matrices detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A facile solvothermal method was developed for synthesis of magnetic nickel-based iron oxide nanocomposites (MNFOs) with different ratios of Ni 2+ to Fe 3+ for different reaction time. Two factors including dosage of Ni source and length of reaction were investigated for influence on the morphology and composition of MNFOs, as well as their distinct selectivity for different phosphopeptides. After thorough characterization, the possible formation mechanism of MNFOs was proposed. Very interestingly, MNFOs with Ni 2+ /Fe 3+ ratios of 4:5 prepared for 8 h (MNFO-S) and for 24 h (MNFO-L) can selectively capture global- and monophosphopeptides at the fmol level with excellent enrichment performance. These two affinity probes have been exploited to isolate and enrich the phosphopeptides from human normal hepatic cells HL 7702 after exposure to atmospheric fine particulates (PM 2.1 ), which revealed that the protein phosphorylation level was increased significantly in cells after stimulation by fine particulate matters. The findings could provide a new insight for the nickel-based affinity protocol to analyze the mutation of phosphopeptides during cellular signaling pathways in response to exogenous environment stimulation. Consequently, this present work proposed a promising strategy to isolate monophosphopeptides from global phosphopeptides for phosphoproteome research.

In order to assess and optimize frequently used in vitro inhalation bioaccessibility procedures for heavy metals in the inhalation risk assessment, in vivo inhalation bioavailability of Pb in simulated atmosphere fine particles (PM 2.5 ) from aging soils spiked with lead compounds and field soils in lead-zinc mining areas was investigated via intranasally instilled experiments with these PM 2.5 suspensions to mice and Pb bioaccessibility was extracted by using four frequently used in vitro procedures (Gamble Solution, simulated lung fluid, simulated epithelial lung fluid and artificial lysosomal fluid). Mouse exposure experiments showed that Pb was mainly distributed in the liver, kidneys, blood and spleen. Based on the kidney model, in vitro inhalation bioaccessibility of Pb extracted with optimized Gamble Solution, in which solid to liquid ratio (S/L) was optimized to 1:1000 g ml -1 and DTPA was proved to be the key effective component, showed a strong linear relationship with its in vivo inhalation bioavailability (y = 1.07x - 3.86, R 2  = 0.73). Moreover, in vitro bioaccessible and bioavailable fractions of Pb were mainly from acid exchangeable and reducible fractions of Pb in PM 2.5 . Altogether, optimized Gamble Solution was suggested for the analysis of in vitro bioaccessibility for risk-based assessments., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A porous zwitterionic monolithic column was prepared to rapidly and efficiently separate lysozyme from egg white. The monolith was synthesized in a stainless steel HPLC column (5 cm × 4.6 mm i.d.) by in-situ thermal initiated co-polymerization of N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium betaine (MSA) and ethylene dimethacrylate (EDMA). Due to the combination of quaternary ammonium and sulfonic groups on the monolithic matrix in one-pot process, the hydrophobic carbon chain and hydrophilic radical were obtained, which provided multiple driving forces for neutral, basic and acidic analytes, thus mix-mode chromatography mechanism contributed to the retention of different charged proteins. Properties such as composition, morphology and stability of the MSA-co-EDMA monolithic column were characterized by various analytical methods and the results showed that the monolith has large through-pores, good hydrophilicity and permeability. The effects of mobile phase pH and ionic strength on proteins were investigated, drawing the conclusion that the main adsorption and elution mechanism of lysozyme on MSA-co-EDMA monolith was electrostatic interaction, while those of other proteins included hydrophobic, hydrophilic and electrostatic interactions. Therefore, efficient separation of lysozyme and other proteins could be successfully achieved by switching the pH of mobile phase. Lysozyme can be adsorbed using 20 mmol/L phosphate buffer (pH 7.0) and eluted with 20 mmol/L phosphate buffer (pH 2.0). To prove the practicality of the monolithic column, it was also applied in the separation of lysozyme in egg white, which means the work has the potential for further development in proteome analysis of real biological samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The increasing application of engineered nanoparticles such as silver nanoparticles (nAg) and zinc oxide nanoparticles (nZnO), results in their accumulation in environmental media. The environmental natural organic matter (NOM) adsorbed by these nanoparticles may have great effects on the aggregation and dissolution of metall ions, which are interesting and important for the assessment of the inhalation risks of these airborne suspended NOM-coated nanoparticles to humans. Therefore, the aggregation and dissolution of nAg and nZnO pretreated with citric acid (CA), tartaric acid (TA) and fulvic acid (FA) in simulated lung biological fluids (artificial lysosomal fluid (ALF) and Gamble Solution) were investigated. The surface properties, morphology and size of the NOM-treated ENPs changed, but the crystalline phase was relatively stable when observed using surface-enhanced Raman scattering, transmission electron microscope, and X-ray diffraction. NOM treatment had no significant influence on the particle size of NOM-treated nAg and nZnO except for a decrease in the size of CA-treated nAg, and it could not promote the aggregation of NOM-treated nAg and nZnO except for the aggregation of TA-treated nAg in Gamble Solution or TA-treated nZnO in ALF. CA- and FA-treatments promoted the release of Zn 2+ and Ag + , respectively, while no promotion was observed after TA-treatment. Therefore, NOM affects the release of Zn 2+ and Ag + from NOM-treated nAg and nZnO but does not promote the aggregation of NOM-treated nAg and nZnO, which influences the inhalation risk-based assessment., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Carboxyl-group functionalized mesoporous silica (CFMS) prepared by one-pot co-condensation method was employed for the solid phase extraction (SPE) of chromium species for the first time. A new approach of SPE coupled to inductively coupled plasma mass spectrometry (ICP-MS) was thus established for the speciation of chromium in environmental water samples. The influences of pH, volume of sample, extraction time, amount of adsorbent, elution conditions, co-existing ions and adsorption capacity were investigated on adsorption or elution of chromium species. Cr(VI) was not retained on the CFMS material in the pH range of 1.0-9.0, while Cr(III) was quantitatively adsorbed at pH 5.0-9.0. The captured Cr(III) was enriched by using 1.5 mol L -1 HNO 3 as elution solvent and detected by ICP-MS. Under the optimized SPE conditions, the maximum adsorption capacity of the CFMS for Cr(III) was 57.67 mg g -1 and the enrichment factor was 25, with the detection limit (LOD) of 0.02 μg L -1 . The proposed protocol has been successfully applied to chromium speciation in rain, lake and river water samples, which exhibited a prospect in field separation and enrichment of chromium species in environmental waters., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A thiol- and amine-bifunctionalized organic-inorganic hybrid monolithic column was prepared for the first time via one-pot co-condensation of 3-mercaptopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane and tetraethylorthosilicate, and utilized for separation and enrichment of inorganic arsenic species. Various parameters of solid phase microextraction (SPME) operation and analytical performance were also investigated systematically. Under the optimum condition, both As(III) and As(V) can be adsorbed over a wide pH range (3.0-8.0) and eluted in turn, in which 3% HNO 3 (v/v) was firstly used to selectively release As(V), and then 3% HNO 3 with 0.01 mol L -1 KIO 3 or 15% mercaptosuccinic acid (MSA) (m/v) to selectively release As(III). Meanwhile, the elution mechanism of As(III) and As(V) was elucidated comprehensively, and notably, the novel eluent, HNO 3 + MSA, was recommended for eluting As(III). Therefore, the thiol- and amine-bifunctionalized organic-inorganic hybrid monolithic column as an ideal SPME matrix for the speciation analysis of arsenic in environmental waters has the merits of facile preparation, low cost, high adsorption capacity and selective desorption. In addition, compared with thiol- and amine-bifunctionalized mesoporous silica, the bifunctional hybrid monolith based SPME protocol with less time and reagent consumption is promising to be applied not only to filed sampling but also to on-line analysis., (Copyright © 2018. Published by Elsevier B.V.)

Cadmium is considered one of the most harmful carcinogenic heavy metals in the human body. Although many scientists have performed research on cadmium toxicity mechanism, the toxicokinetic process of cadmium toxicity remains unclear. In the present study, the kinetic response of proteome in/and A549 cells to exposure of exogenous cadmium was profiled. A549 cells were treated with cadmium sulfate (CdSO 4 ) for different periods and expressions of proteins in cells were detected by two-dimensional gel electrophoresis. The kinetic expressions of proteins related to cadmium toxicity were further investigated by reverse transcription-polymerase chain reaction and western blotting. Intracellular cadmium accumulation and content fluctuation of several essential metals were observed after 0-24 hours of exposure by inductively coupled plasma mass spectrometry. Fifty-four protein spots showed significantly differential responses to CdSO 4 exposure at both 4.5 and 24 hours. From these proteins, four expression patterns were concluded. Their expressions always exhibited a maximum abundance ratio after CdSO 4 exposure for 24 hours. The expression of metallothionein-1 and ZIP-8, concentration of total protein, and contents of cadmium, zinc, copper, cobalt and manganese in cells also showed regular change. In synthesis, the replacement of the essential metals, the inhibition of the expression of metal storing protein and the activation of metal efflux system are involved in cadmium toxicity., (© 2018 John Wiley & Sons, Ltd.)

A comprehensively comparative study of thiol-functionalized mesoporous silica and organic-inorganic hybrid monolithic column was reported, aiming at the separation and enrichment of inorganic arsenic. Thiol-functionalized mesoporous silica was synthesized based on the one-step co-condensation method. At the same time, a novel thiol-functionalized organic-inorganic hybrid monolithic column was synthesized using an unconventional ternary weak basic solvent system via one-step sol-gel process. The approach to prepare monolithic column through mild condition remarkably improved delamination phenomenon of thiol-functionalized hybrid monolithic column easily caused by conventional methods. As(III) can be selectively uptaken by the hybrid monolithic column and homemade syringe-based solid phase extraction device containing mesoporous silica through chelation in a wide range of pH, while As(V) cannot, and then the captured As(III) was eluted by 3% HNO 3 (v/v) with 0.01 mol L -1 KIO 3 . Under the optimized conditions, the extraction recoveries were 91-102% and 93-103% for mesoporous silica and monolithic column, respectively. Although both two materials were ideal solid matrices for the removal and speciation analysis of As(III) in environmental waters, the monolith-based solid phase microextration protocol was more fast and reagent-saving than the other, which endued monolithic columns with more application prospects for trace elemental analysis and speciation. Even so, the exploration of mesoporous silica could efficiently pilot the synthesis of monolithic columns., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this paper, a monolithic octadecylsilane column and particle-packed octadecylsilane columns were used to investigate the retention behaviors of oligonucleotides by ion-pair reversed-phase liquid chromatography (IP-RPLC). Results showed that, with same base composition, hairpin oligonucleotides always had weaker retention than corresponding random coil oligonucleotides on the monolithic column, but not on the particle-packed columns. In addition, the linear correlation between the retention factor k of oligonucleotides and the reciprocal of temperature (1/T), especially for hairpins, was relatively weaker on the particle-packed columns, as compared to the correlation on the monolithic column. The correlation between k and 1/T became weaker with decreasing particle size of the particle-packed columns. Moreover, results revealed that the overall retention order on the particle-packed column with small particles (3 μm) differed greatly from that on the monolithic column. In contrast, the retention order on the 10 μm particle-packed column was very close to that on the monolithic column. From the above, we inferred that oligonucleotides could keep their primary conformations unchanged when passing through the monolithic column, attributed to the special pore structures of the monolith. However, the conformations of oligonucleotides were suppressed or even destroyed when oligonucleotides passed through the particle-packed columns. This because the narrow and tortuous channels created by the stacked stationary phase particles could lead to more complex and unequable retention behaviors. Therefore, the monolithic column exhibited better retention regularity for oligonucleotides of secondary structure especially for hairpins than the particle-packed columns. It is noteworthy that the monolith-based IP-RPLC opens an intriguing prospect in accurately elucidating the retention behaviors of oligonucleotides., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The airborne particle-bound elements (Ca, Fe, Al, Mg, K, Na, Zn, Mn, P, Pb, Cu, Sr, Ti, Ba, Cr, Ni, As, Sb, Cd, Co, and V) trapped in room air conditioners' filters (filter dusts) during recirculating indoor air from different types of rooms were analyzed, and the objectives of this study were to assess the potential sources of those elements and their potential health risks via inhalation/ingestion exposure. Main crustal elements such as Ca, Fe, Al, Mg, and K with an average value of 60.6, 17.9, 11.3, 7.58, and 6.90 mg g -1 , respectively, are the preponderant elements, and the mean values of main toxic elements were 2230, 344, 508, 85.7, 71.5, 36.0, 8.02, and 16.9 mg kg -1 for Zn, Cu, Pb, Cr, Ni, As, Cd, and Sb, respectively. The enrichment factors indicated the significant enrichment of Cd, Pb, Cr, Cu, Sb, and Zn in the filter dusts. Four potential sources with the contributions of 33.5, 29.1, 22.6, and 14.8%, respectively, were identified by absolute principal component scores-multiple linear regression analysis (APCS-MLR). Enrichment factor and APCS-MLR model reveal the outdoor input of toxic elements. In vitro inhalation and ingestion bioaccessibility of toxic elements showed elemental and in vitro procedure dependence. There are potential carcinogenic risks via ingestion exposure and no non-carcinogenic risks to both children and adults based on bioaccessible contents of toxic elements. This study reveals the potential health risks posed by the particle-bound elements.

In this work, retention behaviors of oligonucleotides and double-stranded deoxyribonucleic acids (dsDNAs) have been investigated in ion-pair reversed-phase liquid chromatography (IP-RPLC). We demonstrated that classic linear solvent strength (LSS) model is applicable for describing isocratic retention of oligonucleotides and dsDNAs, which indicated that nucleic acids share the similar retention mechanism as other common small molecules in IP-RPLC. The separation of nucleic acids in IP-RPLC is driven by both hydrophobic and electrostatic interactions. We defined the parameter lnk w /S obtained from LSS model in IP-RPLC as chromatographic hydrophobic and electrostatic interaction index (CHEI). CHEI of a nucleic acid has been revealed to correlate well with its gradient retention time. Notably, we proposed a strategy for retention prediction based on CHEI and base sequence information of nucleic acids. Corresponding to base locus, each base sequence is converted to a featured locus vector consisting of zeros and ones. CHEI prediction models were established by support vector regression (SVR) algorithm with locus vectors. Predicted CHEI values have been applied to predict retention times under desired gradient elution runs. This protocol is easy to grasp and worth pursuing further development for more precise retention prediction performance of nucleic acids in IP-RPLC., (Copyright © 2018. Published by Elsevier B.V.)

Polymorphism is inherent for G-quadruplexes (G4s), and the different structural forms are important for the participation in different biological functions of telomeres. A lot of progress has been made in the exploration of G4 polymorphism. However, quick separation and reliable assessment methods for different conformations of G4 are still very few. In this work, the polymorphism of three sequences d[(G 3 T) 3 G 3 ], d[(G 3 C) 3 G 3 ] and d[(G 3 T) 4 ] annealed in six different solutions were investigated by means of reversed-phase high performance liquid chromatography (RP-HPLC), liquid chromatography-mass spectrometry (LC-MS), fluorescence spectroscopy, circular dichroism spectroscopy, together with native-polyacrylamide gel electrophoresis. Different G4 conformations of these three sequences can be separated clearly by RP-HPLC, and further characterized by on-line LC-MS analysis. It is revealed that high-order structures other than intramolecular quadruplexes were favored for d[(G 3 T) 3 G 3 ] and d[(G 3 C) 3 G 3 ] under the annealing conditions. However, flanking loop impeded d[(G 3 T) 4 ] to form higher-order structures than dimer. In addition, the nature and concentration of cation, as well as the annealing solution component, all have decent influence on the stability and relative ratios of various G4 building blocks. Based on the above findings, RP-HPLC and LC-MS combined with spectroscopic techniques can be used as a facile and powerful tool for quick separation and identification of G4s in solutions, and for effective assessment of DNA sequences and annealing environments on G4 polymorphism. The established protocol provides a novel strategy for evaluating G4 polymorphism, which will facilitate studies on quadruplex structures and their biophysical properties., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Reversed-phase liquid chromatography (RPLC) based octanol-water partition coefficient (logP) or distribution coefficient (logD) determination methods were revisited and assessed comprehensively. Classic isocratic and some gradient RPLC methods were conducted and evaluated for neutral, weak acid and basic compounds. Different lipophilicity indexes in logP or logD determination were discussed in detail, including the retention factor logk w corresponding to neat water as mobile phase extrapolated via linear solvent strength (LSS) model from isocratic runs and calculated with software from gradient runs, the chromatographic hydrophobicity index (CHI), apparent gradient capacity factor (k g ') and gradient retention time (t g ). Among the lipophilicity indexes discussed, logk w from whether isocratic or gradient elution methods best correlated with logP or logD. Therefore logk w is recommended as the preferred lipophilicity index for logP or logD determination. logk w easily calculated from methanol gradient runs might be the main candidate to replace logk w calculated from classic isocratic run as the ideal lipophilicity index. These revisited RPLC methods were not applicable for strongly ionized compounds that are hardly ion-suppressed. A previously reported imperfect ion-pair RPLC method was attempted and further explored for studying distribution coefficients (logD) of sulfonic acids that totally ionized in the mobile phase. Notably, experimental logD values of sulfonic acids were given for the first time. The IP-RPLC method provided a distinct way to explore logD values of ionized compounds., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Gallic acid (GA) was employed as a reducing agent for facile in situ preparation of gold nanorods (GNRs) in thermoresponsive P(NIPAM-NVP) hydrogel films. Based on the surface-enhanced Raman scattering (SERS) effect of GNRs and the enrichment effect of thermoresponsive hydrogel film on test molecules through a shrinkage process, the obtained P(NIPAM-NVP)/GNRs composites have been used as SERS substrate for the rapid detection of diquat. The influences of substrate pre-treatment, laser wavelength, and sample treatment method on diquat determination have been investigated comprehensively. The results showed the composite material to be a good SERS substrate for highly sensitive detection and a promising preconcentration matrix of diquat. The limit of detection of the proposed protocol was estimated to be 2.7×10 -13 molL -1 for diquat. Notably, diquat could be concentrated with the enrichment factor of about 4 after three times swelling-shrinking processes of the hydrogel film., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A facile solvothermal method for the synthesis of multifunctional magnetic CuFeMnO 4 nanospheres affinity probe (NSAP) with controllable morphology and size was developed for the first time. The CuFeMnO 4 nanospheres combine the brilliant features of Cu 2+ , Fe 3+ , and Mn 2+ ions, so their multifunction performances are embodied by strong coordination to carboxyl and amine groups of peptides (Cu 2+ and Fe 3+ ), special affinity to phosphate groups of phosphopeptides (Fe 3+ and Mn 2+ ), and high magnetic responsiveness in a magnetic field. Their potential as an affinity probe was evaluated for highly effective enrichment, rapid magnetic separation of low-abundance peptides (neutral condition), and effective selective capture of phosphopeptides (acid condition) from various complex biosamples. Notably, CuFeMnO 4 NSAP was explored for highly selective capture and isolation of phosphopeptides from A549 cells after exposure to ZnO nanoparticles for different times. Consequently, we put forward a new nanospinel ferrite-based protocol here to analyze and identify the phosphoproteins/phosphopeptides involved in cellular signaling pathways in response to exogenous stimulation.

The spinel-type magnetic manganese ferrite (MnFe 2 O 4 ) microspheres synthesized by simple solvothermal method were used as a novel adsorbent for selective enrichment and effective isolation of phosphopeptides. The uniform MnFe 2 O 4 magnetic affinity microspheres (MAMSs) had a narrow particle size distribution between 250 and 260nm, and displayed superparamagnetism with a saturation magnetization value of 67.0emu/g. Comprehensively, the possible formation mechanism of MnFe 2 O 4 microspheres with ferric and manganous sources as dual precursors was elucidated by comparison with those of Fe 3 O 4 nanoparticles and MnOOH nanosheets respectively with either ferric or manganous source as single precursor. It was suggested that the spherical or sheet nanostructures could be achieved via secondary recrystallization or Ostwald ripening. The MnFe 2 O 4 MAMSs probe exhibited excellent dispersibility in aqueous solution, and rapid magnetic separation within 15s, as well as good reusability. More importantly, MnFe 2 O 4 was highly selective for phosphopeptides because of the strong coordination interaction between metal ions (Fe 3+ and Mn 2+ ) and phosphate groups of phosphopeptdies. This high specificity was demonstrated by effectively enriching phosphopeptides from digest mixture of β-casein and bovine serum albumin (BSA) with high content of non-phosphopeptides, and embodied further in phosphopeptides enrichment from non-fat milk digests and human serum. Consequently, the prepared MnFe 2 O 4 affinity materials are expected to possess great potential in phosphoproteome research., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This work presents a sequential enrichment protocol, based on two self-designed cerium-based nanocomposite affinity probes, which not only can effectively separate phosphopeptides from non-phosphopeptides but can also selectively differentiate mono- and multi-phosphopeptides for direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOF MS) analysis.

The study on nucleic acid retention in ion-pair reversed-phase high-performance liquid chromatography mainly focuses on size-dependence, however, other factors influencing retention behaviors have not been comprehensively clarified up to date. In this present work, the retention behaviors of oligonucleotides and double-stranded DNAs were investigated on silica-based C 18 stationary phase by ion-pair reversed-phase high-performance liquid chromatography. It is found that the retention of oligonucleotides was influenced by base composition and base sequence as well as size, and oligonucleotides prone to self-dimerization have weaker retention than those not prone to self-dimerization but with the same base composition. However, homo-oligonucleotides are suitable for the size-dependent separation as a special case of oligonucleotides. For double-stranded DNAs, the retention is also influenced by base composition and base sequence, as well as size. This may be attributed to the interaction of exposed bases in major or minor grooves with the hydrophobic alky chains of stationary phase. In addition, no specific influence of guanine and cytosine content was confirmed on retention of double-stranded DNAs. Notably, the space effect resulted from the stereostructure of nucleic acids also influences the retention behavior in ion-pair reversed-phase high-performance liquid chromatography., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel strategy for the preparation of an aptamer based organic-inorganic hybrid affinity monolithic column was developed successfully using gold nanoparticles (GNPs) as an intermediary for a sandwich structure to realize the functional modification of the surface of the monolithic matrix. This monolithic matrix was facilely pre-synthesized via one-step co-condensation. Due to the high surface-to-volume ratio of GNPs and the large specific surface area of the hybrid matrix, the average coverage density of aptamers on the hybrid monolith reached 342 pmol μL(-1). With the combination of an aptamer based hybrid affinity monolithic column and enzymatic chromogenic assay, the quantitation and detection limits of thrombin were as low as 5 nM and 2 nM, respectively. These results indicated that the GNPs attached monolith provided a novel technique to immobilize aptamers on an organic-inorganic hybrid monolith and it could be used to achieve highly selective recognition and determination of trace proteins.

Polydopamine-coated Fe3 O4 magnetic nanoparticles synthesized through a facile solvothermal reaction and the self-polymerization of dopamine have been employed as a magnetic solid-phase extraction sorbent to enrich four phenolic compounds, bisphenol A, tetrabromobisphenol A, (S)-1,1'-bi-2-naphthol and 2,4,6-tribromophenol, from environmental waters followed by high-performance liquid chromatographic detection. Various parameters of the extraction were optimized, including the pH of the sample matrix, the amount of polydopamine-coated Fe3 O4 sorbent, the adsorption time, the enrichment factor of analytes, the elution solvent, and the reusability of the nanoparticles sorbent. The recoveries of these phenols in spiked water samples were 62.0-112.0% with relative standard deviations of 0.8-7.7%, indicating the good reliability of the magnetic solid-phase extraction with high-performance liquid chromatography method. In addition, the extraction characteristics of the magnetic polydopamine-coated Fe3 O4 nanoparticles were elucidated comprehensively. It is found that there are hydrophobic, π-π stacking and hydrogen bonding interactions between phenols and more dispersible polydopamine-coated Fe3 O4 in water, among which hydrophobic interaction dominates the magnetic solid-phase extraction performance., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Intracellular metal elements exist in mammalian cells with the concentration range from picomoles per litre to micromoles per litre and play a considerable role in various biological procedures. Element provided by different species can influence the availability and distribution of the element in a cell and could lead to different biological effects on the cell's growth and function. Zinc as an abundant and widely distributed essential trace element, is involved in numerous and relevant physiological functions. Zinc homeostasis in cells, which is regulated by metallothioneins, zinc transporter/SLC30A, Zrt-/Irt-like proteins/SLC39A and metal-response element-binding transcription factor-1 (MTF-1), is crucial for normal cellular functioning. In this study, we investigated the influences of different zinc species, zinc sulphate, zinc gluconate and bacitracin zinc, which represented inorganic, organic and biological zinc species, respectively, on cell cycle, viability and apoptosis in MDAMB231 cells. It was found that the responses of cell cycle, apoptosis and death to different zinc species in MDAMB231 cells are different. Western blot analysis of the expression of several key proteins in regulating zinc-related transcription, cell cycle, apoptosis, including MTF-1, cyclin B1, cyclin D1, caspase-8 and caspase-9 in treated cells further confirmed the observed results on cell level.

Lichee-like core-shell structured magnetic lutetium phosphate (Fe 3 O 4 @LuPO 4 ) affinity microspheres were successfully synthesized and well characterized. Based on the properties of great specificity and rapid separation, magnetic LuPO 4 microspheres were applied to selectively enrich phosphopeptides for MALDI-TOF MS analysis. The enrichment performance of the prepared microspheres was demonstrated by tryptic digests of standard protein (β-casein), complex samples (tryptic digest mixture of β-casein and bovine serum albumin at different molar ratios of 1 : 10 to 1 : 50), and real biological samples (fresh pure milk and human serum), respectively. The enrichment ability of magnetic LuPO 4 microspheres for phosphopeptides was very satisfying and the captured phosphopeptides with a sharp enhancement in MS signals were reliably identified based on the appearance of metastable ion peaks with poor resolution of the corresponding dephosphorylated peptides in the mass spectra. Enrichment of phosphopeptides by the Fe 3 O 4 @LuPO 4 affinity microspheres provides a powerful approach for large scale phosphoproteome analysis.

An analytical method that combined high-performance liquid chromatography with inductively coupled plasma mass spectrometry has been developed for the determination of hexavalent chromium in traditional Chinese medicines. Hexavalent chromium was extracted using the alkaline solution. The parameters such as the concentration of alkaline and the extraction temperature have been optimized to minimize the interconversion between trivalent chromium and hexavalent chromium. The extracted hexavalent chromium was separated on a weak anion exchange column in isocratic mode, followed by inductively coupled plasma mass spectrometry determination. To obtain a better chromatographic resolution and sensitivity, 75 mM NH4 NO3 at pH 7 was selected as the mobile phase. The linearity of the proposed method was investigated in the range of 0.2-5.0 μg L(-1) (r(2) = 0.9999) for hexavalent chromium. The limits of detection and quantitation are 0.1 and 0.3 μg L(-1) , respectively. The developed method was successfully applied to the determination of hexavalent chromium in Chloriti lapis and Lumbricus with satisfactory recoveries of 95.8-112.8%., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Zinc, an essential trace element, is involved in many important physiological processes. Cell responses to zinc stress show time-dependent effects besides concentration-dependence and tissue-specificity. Herein, we investigated the time-dependent differential expression of the proteome in A549 cells after administered with ZnSO4 for both 9 and 24 h using 2DE. 123 differentially expressed protein spots were detected, most of which were up-regulated by Zn2+ treatment. Interestingly, 49 proteins exhibited significant differential expression repeatedly during these two treatment periods, and moreover showed a conserved change with different ratios and four time-dependent expression patterns. Pattern 1 (up-regulated with rapid initial induction and subsequent repression) and pattern 4 (down-regulated with steady repression) were the predominant expression patterns. The abundances of the proteins in patterns 1 and 4 after 24 h of zinc treatment are always lower than that after 9 h, indicating that exogenous zinc reduced the expression of proteins in cells after 24 h or longer. Importantly, these findings could also reflect the central challenge in detecting zinc homeostasis proteins by 2DE or other high throughput analytical methods resulting from slight variation in protein expression after certain durations of exogenous zinc treatment and/or low inherent protein content in cells. These time-dependent proteome expression patterns were further validated by measuring dynamic changes in protein content in cells and in expression of two proteins using the Bradford method and western blotting, respectively. The time-dependent changes in total zinc and free Zn2+ ion contents in cells were measured using ICP-MS and confocal microscopy, respectively. The kinetic process of zinc homeostasis regulated by muffling was further revealed. In addition, we identified 50 differentially expressed proteins which are predominantly involved in metabolic process, cellular process or developmental process, and function as binding, catalytic activity or structural molecule activity. This study further elucidates our understanding of dynamic nature of the cellular response to zinc stress and the mechanism of zinc homeostasis.

A novel strategy for preparing aptamer-based organic-silica hybrid monolithic column was developed via "thiol-ene" click chemistry. Due to the large specific surface area of the hybrid matrix and the simplicity, rapidness and high efficiency of "thiol-ene" click reaction, the average coverage density of aptamer on the organic-silica hybrid monolith reached 420 pmol μL(-1). Human α-thrombin can be captured on the prepared affinity monolithic column with high specificity and eluted by NaClO4 solution. N-p-tosyl-Gly-Pro-Arg p-nitroanilide acetate was used as the sensitive chromogenic substrate of thrombin. The thrombin enriched by this affinity column was detected with a detection of limit of 0.01 μM by spectrophotometry. Furthermore, the extraction recovery of thrombin at 0.15 μM in human serum was 91.8% with a relative standard deviation of 4.0%. These results indicated that "thiol-ene" click chemistry provided a promising technique to immobilize aptamer on organic-inorganic hybrid monolith and the easily-assembled affinity monolithic material could be used to realize highly selective recognition of trace proteins., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Graphene-doped Fe3O4 nanocomposites were prepared by a solvothermal reaction of an iron source with graphene. The nanocomposites were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, superconducting quantum interference, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. This nanomaterial has been used as a magnetic solid-phase extraction sorbent to extract trace brominated flame retardants from environmental waters. Various extraction parameters were optimized including dosage and reusability of the nanocomposites, and pH of sample matrix. The reliability of the magnetic solid-phase extraction protocol based on graphene-doped Fe3O4 nanocomposites was evaluated by investigating the recoveries of 2,4,6-tribromophenol, tetrabromobisphenol A, 4-bromodiphenyl ether, and 4,4'-dibromodiphenyl ether in water samples. Good recoveries (85.0-105.0%) were achieved with the relative standard deviation ranging from 1.1-7.1%. Moreover, it is speculated from characterization and magnetic solid-phase extraction experiment that there is not only π-π stacking but also possible hydrophobic interaction between the graphene-doped Fe3O4 nanocomposites and analytes., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new magnetic solid phase extraction (MSPE) method using octyl-immobilized silica-coated magnetic Fe3O4 (C8-Fe3O4@SiO2) nanoparticles as the MSPE adsorbent combined with inductively coupled plasma mass spectrometry (ICP-MS) has been developed for speciation analysis of Sb(III) and Sb(V). At pH 5.0, Sb(III) forms a hydrophobic complex with ammonium pyrrolidine dithiocarbamate (APDC) and is retained on C8-Fe3O4@SiO2 nanoparticles, whereas Sb(V) remains as free species in aqueous solution. At pH 2.0, both Sb species (total Sb) form hydrophobic APDC complexes, being retained on the adsorbent. Thus, sensitive speciation analysis of Sb(III) and Sb(V) could be achieved by selective SPE of either Sb(III) or total Sb under different pH on C8-Fe3O4@SiO2 nanoparticles. The experimental parameters, such as pH of solution, concentration of APDC, eluent type and sample volume were optimized in detail. The limits of detection (LOD, 3δ, n=10) of this MSPE method was 0.001 μg L(-1) and 0.004 μg L(-1), respectively, for Sb(III) and Sb(V). The precision of the method (Relative standard deviation, RSD, n=6) for Sb(III) and Sb(V) at 1.0 μg L(-1) was 3.4% and 4.6%, respectively. In order to verify the accuracy of the method, certified reference material (GSB 07-1376-2001) of environmental water was analyzed and the result obtained was in good agreement with the certified values. This proposed method is simple, accurate and sensitive, and can be applied to the speciation of Sb(III) and Sb(V) in environmental waters without any pre-reduction or pre-oxidation operation., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A strategy to utilize neutral model compounds for lipophilicity measurement of ionizable basic compounds by reversed-phase high-performance liquid chromatography is proposed in this paper. The applicability of the novel protocol was justified by theoretical derivation. Meanwhile, the linear relationships between logarithm of apparent n-octanol/water partition coefficients (logKow '') and logarithm of retention factors corresponding to the 100% aqueous fraction of mobile phase (logkw ) were established for a basic training set, a neutral training set and a mixed training set of these two. As proved in theory, the good linearity and external validation results indicated that the logKow ''-logkw relationships obtained from a neutral model training set were always reliable regardless of mobile phase pH. Afterwards, the above relationships were adopted to determine the logKow of harmaline, a weakly dissociable alkaloid. As far as we know, this is the first report on experimental logKow data for harmaline (logKow = 2.28 ± 0.08). Introducing neutral compounds into a basic model training set or using neutral model compounds alone is recommended to measure the lipophilicity of weakly ionizable basic compounds especially those with high hydrophobicity for the advantages of more suitable model compound choices and convenient mobile phase pH control., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Zinc plays a critical role in many biological processes. However, it is toxic at high concentrations and its homeostasis is strictly regulated by metal-responsive transcription factor 1 (MTF-1) together with many other proteins to protect cells against metal toxicity and oxidative stresses. In this paper, we used high-resolution two-dimensional gel electrophoresis (2DE) to profile global changes of the whole soluble proteome in human lung adenocarcinoma (A549) cells in response to exogenous zinc treatment for 24 h. Eighteen differentially expressed proteins were identified by MALDI TOF/TOF and MASCOT search. In addition, we used Western blotting and RT-PCR to examine the time-dependent changes in expression of proteins regulated by MTF-1 in response to Zn treatment, including the metal binding protein MT-1, the zinc efflux protein ZnT-1, and the zinc influx regulator ZIP-1. The results indicated that variations in their mRNA and protein levels were consistent with their functions in maintaining the homeostasis of zinc. However, the accumulation of ZIP-1 transcripts was down-regulated while the protein level was up-regulated during the same time period. This may be due to the complex regulatory mechanism of ZIP-1, which is involved in multiple signaling pathways. Maximal changes in protein abundance were observed at 10 h following Zn treatment, but only slight changes in protein or mRNA levels were observed at 24 h, which was the time-point frequently used for 2DE analyses. Therefore, further study of the time-dependent Zn-response of A549 cells would help to understand the dynamic nature of the cellular response to Zn stress. Our findings provide the basis for further study into zinc-regulated cellular signaling pathways.

Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole-dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A facile and sensitive aptamer-based protocol has been developed for protein assay on microfluidic platform with fluorescence detection using an off-chip microarray scanner. Aptamer-functionalized magnetic beads were used to capture thrombin that binds to a second aptamer fluorescently labeled by Cy3. Experimental conditions, such as incubation time and temperature, washing time, interfering proteins, and aptamer, etc., were optimized for the microchip method. This work demonstrated there was a good relationship between fluorescence intensity and thrombin concentration in the range of 65-1000 ng/mL with the RSD less than 8%. Notably, an analysis only needs 1 μL volume of sample injection and this system can capture extremely tiny amount thrombin (0.4 fmol). This method has been successfully applied to assay of thrombin in human serum with the recovery of 79.74-95.94%., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)