Co-reporter:Qinglan Zhao, Haoyue Xiang, Jun-An Xiao, Peng-Ju Xia, Jun-Jie Wang, Xiaoqing Chen, and Hua Yang
The Journal of Organic Chemistry September 15, 2017 Volume 82(Issue 18) pp:9837-9837
Publication Date(Web):August 17, 2017
DOI:10.1021/acs.joc.7b01339
A practical and straightforward synthetic route through a Selectfluor-triggered tandem cyclization of o-hydroxyarylenaminone was developed to construct a variety of difluorinated 2-amino-substituted chromanones. This novel protocol features mild reaction conditions, operational simplicity, and broad substrate scope. The enamine moiety in o-hydroxyarylenaminone played dual roles to enable high efficiency in the difluorination and intramolecular cyclization, leading to the accomplishment of a new class of difluorinated 2-amino-substituted chromanones for pharmaceutical studies.
Co-reporter:Miao Chen, Wen Luo, Zhimin Zhang, Ranhao Wang, Yuqiu Zhu, Hua Yang, and Xiaoqing Chen
ACS Applied Materials & Interfaces December 6, 2017 Volume 9(Issue 48) pp:42156-42156
Publication Date(Web):November 15, 2017
DOI:10.1021/acsami.7b16618
Surface-enhanced Raman-scattering-based (SERS-based) biosensing in biological fluids is constrained by nonspecific macromolecule adsorptions and disposable property of the SERS substrate. Here, novel multi-Au-nanoparticle-embedded mesoporous silica microspheres (AuNPs/mSiO2) were prepared using a one-pot method, which served as reliable substrates for SERS enhancement associated with salient features of self-filtering ability and reusability. The fabrication and physical characterization of AuNPs/mSiO2 microspheres were discussed, and SERS activity of this novel substrate was investigated by using 4-mercaptobenzoic acid (4-MBA) as Raman probe. The responses of our substrates to Raman intensities exhibited a SERS enhancement factor of 2.01 × 107 and high reproducibility (relative standard deviation of 6.13%). Proof-of-concept experiments were designed to evaluate the self-filtering ability of the substrates in bovine serum albumin (BSA) and human serum solution, separately. The results clearly demonstrate that mesoporous SiO2 can serve as a molecular sieve via size exclusion and avoid Raman signal interference of biomacromolecules in biological fluids. Subsequently, feasibility of practical application of AuNPs/mSiO2 microspheres was assessed by quantitative detection of methotrexate (MTA) in serum. The method exhibited good linearity between 1 and 110 nM with the correlation coefficients of 0.996, which proved that the obtained AuNPs/mSiO2 microspheres were good SERS substrates for determination of small biomolecules directly in biological fluids without need of manipulating samples. In addition, the substrate maintained its SERS response during multiple cycles, which was evaluated by recording Raman signals for 4-MBA before and after thermal annealing, thereby demonstrating the high thermostability and satisfactory reusability. These results offered the AuNPs/mSiO2 microspheres attractive advantages in their SERS biosensing.Keywords: human serum; mesoporous silica microspheres; methotrexate; reusable substrates; self-filtering; surface-enhanced Raman scattering (SERS);
Co-reporter:Haoyue Xiang, Qinglan Zhao, Zhenyu Tang, Junan Xiao, Pengju Xia, Chaoming Wang, Chunhao Yang, Xiaoqing Chen, and Hua Yang
Organic Letters 2017 Volume 19(Issue 1) pp:146-149
Publication Date(Web):December 12, 2016
DOI:10.1021/acs.orglett.6b03441
A practical and straightforward synthetic route to construct a variety of 3-CF2/CF3-containing chromones via photoredox catalysis was developed. This novel protocol features a visible-light-induced radical-triggered tandem cyclization.
Co-reporter:Fen Tang, Yixi Xie, Hui Cao, Hua Yang, Xiaoqing Chen, Jianbo Xiao
Food Chemistry 2017 Volume 219() pp:321-328
Publication Date(Web):15 March 2017
DOI:10.1016/j.foodchem.2016.09.154
•The structure-stability relationships of resveratrol analogues in FBS.•The oxidation process is not the single factor governing the stability of resveratrol analogues.•FBS masks the free radical scavenging potential of resveratrol analogues.Fetal bovine serum (FBS) is a universal growth supplement of cell and tissue culture media. Herein, the influences of FBS on the stability and antioxidant activity of 21 resveratrol analogues were investigated using a polyphenol-protein interaction approach. The structure-stability relationships of resveratrol analogues in FBS showed a clear decrease in the stability of hydroxylated resveratrol analogues in the order: resorcinol-type > pyrogallol-type > catechol-type. The glycosylation and methoxylation of resveratrol analogues enhanced their stability. A linear relationship between the stability of resveratrol analogues in FBS and the affinity of resveratrol analogues-FBS interaction was found. The oxidation process is not the only factor governing the stability of resveratrol analogues in FBS. These results facilitated the insightful investigation of the role of polyphenol-protein interactions in serum, thereby providing some fundamental clues for future clinical research and pharmacological studies on natural small molecules.
Co-reporter:Miao Chen, Wen Luo, Zhimin Zhang, Fawei Zhu, Sen Liao, Hua Yang, Xiaoqing Chen
Talanta 2017 Volume 171(Volume 171) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.talanta.2017.04.072
•A novel approach for fabricating core-shell-satellite magnetic microspheres was developed.•Utilizing positively charged mSiO2 to anchor AuNPs and enrich the methotrexate.•Rapid SERS detection of methotrexate (LOD: 1 nM, linear range: 1–200 nM).An effective approach for fabricating core-shell-satellite magnetic microspheres was developed to form a sub-10 nm positively charged mesoporous silica (mSiO2) interlayer, which was applied to enrich samples and create sufficient hotspots between the inner Fe3O4@Ag core and outer assembled gold nanoparticles (AuNPs) satellites. Based on the prepared Fe3O4@Ag/mSiO2/AuNPs (FASA) as SERS substrates, a sensitive and label-free detection of methotrexate in serum was successfully realized. The positively charged mSiO2 interlayer exhibited strong capability in enriching methotrexate through the electrostatic interaction. The intraparticle plasmonic coupling between the inner Ag shell and the outside AuNPs satellites, and magnetism-induced aggregation greatly enhanced the SERS activity of methotrexate. The diluted serum containing different concentrations of methotrexate was employed as real samples and the minimum detected concentration of methotrexate was as low as 1 nM with a linear response range from 1 to 200 nM. This sensitive and label-free SERS detection of methotrexate based on FASA offers great potential for practical applications in medicine and biotechnology.Download high-res image (231KB)Download full-size image
Co-reporter:Miao Chen, Zhimin Zhang, Minzhuo Liu, Chen Qiu, Hua Yang, Xiaoqing Chen
Talanta 2017 Volume 165() pp:313-320
Publication Date(Web):1 April 2017
DOI:10.1016/j.talanta.2016.12.072
•A label-free optical sensing paper strip for SERS detection of BRs was fabricated.•Utilizing γ-PGA as the linker and concentrator for in situ growth AuNPs on paper.•Highly reproducibility and sensitive (RSD: 4.78%, LOD:1×10−11 M, EF:1.13×108).•Rapid detection of BRs in plant tissues: RSD values in a range of 3.0–13.8%.A surface-enhanced Raman scattering (SERS)-functionalized, gold nanoparticle (AuNPs)-immobilized paper strip was developed to realize label-free rapid detection of brassinosteroids (BRs) in plant tissues. The AuNPs paper strip was fabricated through utilizing poly(γ-glutamic acid) (γ-PGA) as the linker and concentrator for the directly immobilized AuNPs on paper, which can circumvent many drawbacks of the existing SERS substrates. An enhancement factor of 1.13×108, high reproducibility (relative standard deviation of 4.78%), highly sensitive detection limit with a correlation coefficient of 0.99 (1×10–11 M 4-mercaptophenylboronic acid), and long-term stability for the responses of the SERS-functionalized AuNPs paper strip to Raman intensities were achieved by optimizing reaction conditions including the concentrations of γ-PGA and HAuCl4/NaBH4. Ultimately, this developed paper strip was applied to the determination of BRs in plant tissues, obtaining precisions with RSD values in a range of 3.0–13.8%. The SERS-functionalized AuNPs paper strip featuring label-free rapid analysis, and high sensitivity could serve as an excellent alternative for on-site rapid detections.
Co-reporter:Zhi-Liang Wu, Cheng-Kun Li, Jin-Gang Yu, Xiao-Qing Chen
Sensors and Actuators B: Chemical 2017 Volume 239() pp:544-552
Publication Date(Web):February 2017
DOI:10.1016/j.snb.2016.08.062
•Novel composites—manganese dioxide/graphene nanoribbons (MnO2/GNRs) were developed.•MnO2/GNRs were fabricated by a facile and single-step hydrothermal co-reduction reaction.•MnO2/GNRs displayed high activity for the electrocatalytic oxidation of H2O2.•MnO2/GNRs based amperometric sensor possessed good sensitivity and selectivity to H2O2.In the present work, graphene oxide nanoribbons (GONRs) were synthesized via the longitudinal unzipping of multi-walled carbon nanotubes (MWCNTs) nanoparticles with the aid of strong oxidants. The MnO2/reduced graphene oxide Nanoribbons (MnO2/rGONRs) composites were successfully fabricated by means of a reproducible and single-step hydrothermal co-reduction of KMnO4 and GONRs. The morphology and composition of as-prepared materials were studied by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). The as-prepared MnO2/rGONRs were employed in fabricating a nonenzymatic electrochemical sensor for the sensitive detection of hydrogen peroxide (H2O2). The electrochemical properties of the MnO2/rGONRs modified glassy carbon electrode (MnO2/rGONRs/GCE) were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The developed nonenzymatic electrochemical sensor exhibited well-defined amperometric response towards H2O2 in a wide linear range of 0.25–2245 μM, and a detection limit of 0.071 μM (S/N = 3) could be obtained. And the proposed sensor also displayed excellent electrochemical analytical performance, acceptable reproducibility, high accuracy, and great anti-interference ability. The proposed sensor was applied for the determination of H2O2 in real sample of fetal bovine serum (FBS), and acceptable accuracy and recovery could be obtained.
Co-reporter:Chengkun Li, Zhiliang Wu, Hua Yang, Liu Deng, Xiaoqing Chen
Sensors and Actuators B: Chemical 2017 Volume 251(Volume 251) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.snb.2017.05.059
•A novel composite — reduced graphene oxide-cyclodextrin-chitosan was developed.•The self-assembly of composite was achieved under the chemical effects of ultrasound.•The composite based electrochemical sensor displayed good performance for simultaneous detection of nitrophenols.•The composite possessed high selectivity toward nitrophenols.A novel electrochemical sensor based on cyclodextrin and chitosan-functionalized reduced graphene oxide composite film was designed and prepared to detect o- and p-nitrophenols simultaneously. Apart from the synergistic effect of large specific surface area of reduced graphene oxide (RGO), the adsorption of nitrophenols (NPhs) through electrostatic interaction benefited from large quantities of host–guest recognition sites on cyclodextrin (CD) and abundant functional groups on chitosan. By taking advantage of the salient features of RGO, CDs, and chitosan, p-nitrophenol (p-NPh) and o-nitrophenol (o-NPh) can be determined simultaneously based on their nitroaromatic/hydroxylamine redox reactions. Under the optimized experimental conditions, a wide linear range was obtained over o-NPh concentration from 0.12 μM to 0.28 μM and 5 μM to 40 μM with a detection limit of 0.018 μM (S/N = 3) as well as p-NPh concentration from 0.06 μM to 0.16 μM and 5 μM to 40 μM along with a detection limit of 0.016 μM (S/N = 3). In addition, the newly developed reduced graphene oxide-cyclodextrin-chitosan (RGO-CD-CS) sensor displayed high accuracy, satisfactory reproducibility, good stability, and adequate efficiency in simultaneously detecting o-NPh and p-NPh in aqueous samples.
Co-reporter:Jun Wang, Qi Liu, Liya Rong, Hua Yang, Feipeng Jiao, Xiaoqing Chen
Journal of Chromatography A 2016 Volume 1467() pp:490-496
Publication Date(Web):7 October 2016
DOI:10.1016/j.chroma.2016.06.054
•Novel ATPS composed of acetone and β-CD derivative was developed.•β-CD derivative simultaneously serves as phase-forming agent and chiral selector.•The calculated TLs data were successfully correlated by several empirical equations.•Enantioselective extraction conditions for rac-PSA were rapidly and accurately optimized using RSM.A novel aqueous two-phase system (ATPS) composed of β-cyclodextrin (β-CD) derivative and acetone was developed for enantioselective extraction of racemic phenylsuccinic acid (PSA). Binodal curves, tie-lines, and critical points for the investigated ATPS were determined and the experimental tie-lines data were successfully correlated by Othmer-Tobias, Bancroft, and Setschenow-type equations. ATPS containing sulfobutyl ether-β-CD (SBE-β-CD) exhibited better enantioselectivity than that using carboxymethyl-β-CD (CM-β-CD). To optimize enantioselective partitioning conditions of PSA in acetone/SBE-β-CD ATPS, three factors (PSA concentration, pH, and equilibrium temperature) were analyzed by using central composite design in response surface methodology. The calculated equilibrium constants of inclusion complexation are 1638.64 M−1 for SBE-β-CD-(R)-PSA and 835.84 M−1 for SBE-β-CD-(S)-PSA, respectively. Under the optimized conditions, the separation factor of 3.14 and high enrichment efficiency (ER = 98.06%, ES = 99.25%) were simultaneously achieved in a single step.
Co-reporter:Hui Cao, Xueping Jia, Jian Shi, Jianbo Xiao, Xiaoqing Chen
Food Chemistry 2016 Volume 202() pp:383-388
Publication Date(Web):1 July 2016
DOI:10.1016/j.foodchem.2016.02.003
•The structure–affinity relationship of stilbenoid–protein interaction.•The influence of protein binding on the stability and bioactivity.•The effects of polyphenol–protein interaction on the cell uptake.Dietary stilbenoids are associated with many benefits for human health, which depend on their bioavailability and bioaccessibility. The stilbenoid–human serum albumin (HSA) interactions are investigated to explore the structure–affinity relationship and influence on the stability, free radical scavenging activity and cell uptake of stilbenoids. The structure–affinity relationship of the stilbenoids–HSA interaction was found as: (1) the methoxylation enhanced the affinity, (2) an additional hydroxyl group increases the affinity and (3) the glycosylation significantly weakened the affinity. HSA obviously masked the free radical scavenging potential of stilbenoids. The stabilities of stilbenoids in different medium were determined as: HSA solution > human plasma > Dulbecco’s modified Eagle’s medium. It appears that the milk enhanced the cell uptake of stilbenoids with multi-hydroxyl groups and weakened the cell uptake of stilbenoids with methoxyl group on EA.hy 926 endothelial cells. The stilbenoids are hardly absorbed by human umbilical vein endothelial cells in the presence of milk.The potential sites of stilbenoids affecting the binding affinity for HSA are schematically illustrated. The up arrows represent increasing the affinity, the down arrows represent decreasing the affinity.
Co-reporter:Zhi-Liang Wu, Fang Liu, Cheng-Kun Li, Xiao-Qing Chen, Jin-Gang Yu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 509() pp:65-72
Publication Date(Web):20 November 2016
DOI:10.1016/j.colsurfa.2016.08.084
•Superior graphene-based adsorbent of PPD-GO was successfully prepared.•The aqueous adsorption of Congo red by PPD-GO was investigated.•PPD-GO exhibits excellent adsorption performance.•The whole adsorption process was investigated systematically.In this work, a novel sandwich-structured graphene-based composite (PPD-GO) was prepared. The graphene-based composite was prepared by amination of graphene oxide (GO) with p-phenylenediamine (PPD) with the aid of the coupling reagents. And PPD was introduced into the interlayers of graphene nanosheets. The morphology, composition, and grafted functional groups of the composite were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. And PPD-GO was used as a highly efficient adsorbent for removal of Congo red from used from aqueous solutions. The whole adsorption process was studied in depth and elucidated systematically. A maximum Congo red adsorption capacity of 892.8 mg/g was obtained for PPD-GO composite at an initial temperature of 298 K and pH of 3.0. The second-order kinetic equation could well describe the sorption kinetics. The equilibrium data were perfectly fitted by the Langmuir isotherm. The thermodynamic analysis indicated that the adsorption of Congo red onto the PPD-GO composite was a spontaneous and endothermic process.Schematic for the preparation of PPD-GO.
Co-reporter:Liya Rong, Qi Liu, Jun Wang, Hualiang Zeng, Hua Yang, Xiaoqing Chen
Tetrahedron: Asymmetry 2016 Volume 27(7–8) pp:301-306
Publication Date(Web):1 May 2016
DOI:10.1016/j.tetasy.2016.03.001
High-speed counter-current chromatography combined with closed recycling elution mode was developed to enantioseparate (RS)-ibuprofen by using hydroxypropyl-β-cyclodextrin (HP-β-CD) as the chiral selector. Key parameters for high-speed counter-current chromatography resolution including the concentration of HP-β-CD, the two-phase solvent system composition, equilibrium temperature, and the pH of aqueous phase were extensively investigated. Under the optimized conditions, the enantiomers of ibuprofen were successfully separated by preparative recycling high-speed counter-current chromatography and the resulting enantiopurity of each enantiomer was over 97.5% as determined by HPLC. Moreover, the recovery for (R,S)-ibuprofen from high-speed counter-current chromatography fractions was achieved in the range of 82–89%.
Co-reporter:Shujing Jiang, Qi Liu, Yixi Xie, Hualiang Zeng, Li Zhang, Xinyu Jiang, Xiaoqing Chen
Food Chemistry 2015 Volume 186() pp:153-159
Publication Date(Web):1 November 2015
DOI:10.1016/j.foodchem.2014.08.120
•Extract of the tartary buckwheat grains was subjected for HSCCC separation for the first time.•Off-line 2D HSCCC with two solvent systems was established to isolate target compounds.•Five flavonoids with high purities were isolated and identified.An off-line two dimensional (2D) high-speed counter-current chromatography (HSCCC) strategy was successfully used for preparative separation of five flavonoids from tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) grains with different solvent systems for the first time in this paper. n-Hexane–ethyl acetate–methanol–water 3:5:3:5 (v/v) was selected as the first dimension solvent system to purify quercetin (4) and kaempferol (5). The second dimension solvent system, ethyl acetate–n-butanol–water 7:3:10 (v/v), was used to isolate quercetin 3-O-rutinoside-3′-O-β-glucopyranoside (1), rutin (2) and kaempferol 3-rutinoside (3). The purities of these compounds were all above 96.0% and their structures were identified through UV, MS and 1H NMR. The results indicated that the off-line 2D HSCCC is an efficient technique to isolate flavonoids compounds from grains.
Co-reporter:Qi Liu, Hualiang Zeng, Shujing Jiang, Li Zhang, Fuzhu Yang, Xiaoqing Chen, Hua Yang
Food Chemistry 2015 Volume 186() pp:139-145
Publication Date(Web):1 November 2015
DOI:10.1016/j.foodchem.2014.09.037
•The extract from leaves of Malus hupehensis (Pamp.) Rehder was subjected to HSCCC separation for the first time.•Off-line 2D strategy was adopted for the HSCCC separation.•Two parallel recycling HSCCCs were successfully employed to isolate intractable compounds 1, 2 and 3.In this study, off-line two-dimensional High Speed Counter-Current Chromatography (2D HSCCC) strategy combined with recycling elution mode was developed to isolate compounds from the ethyl acetate extract of a common green tea – leaves of Malus hupehensis (Pamp.) Rehder. In the orthogonal separation system, a conventional HSCCC was employed for the first dimension and two recycling HSCCCs were used for the second in parallel. Using a solvent system consisting of n-hexane–ethyl acetate–methanol–water (1:4:0.6:4.4, v/v) in the first and second dimension, four compounds including 3-hydroxy-phlorizin (1), phloretin (2), avicularin (3) and kaempferol 3-O-β-d-glucoside (4) were obtained. The purities of these four compounds were all over 95.0% as determined by HPLC. And their structures were all identified through UV, MS and 1H NMR. It has been demonstrated that the combination of off-line 2D HSCCC with recycling elution mode is an efficient technique to isolate compounds with similar polarities in natural products.
Co-reporter:Dongxue Wang, Liangliang Liu, Xinyu Jiang, Jingang Yu, Xiaohong Chen, Xiaoqing Chen
Applied Surface Science 2015 Volume 329() pp:197-205
Publication Date(Web):28 February 2015
DOI:10.1016/j.apsusc.2014.12.161
Highlights
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Magnetic β-cyclodextrin-graphene oxide (MCG) show high adsorption capacity.
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The maximum adsorption capacity was 1102.58 mg/g at 45 °C and pH 8.
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MCG can be easily and fast extracted from water by magnetic attraction.
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Removal rate of MCG could reach 98% after three times of adsorption.
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Adsorption capacity of MCG remained at 81% after five cycles.
Co-reporter:Li Zhang;Qi Liu;Jingang Yu;Hualiang Zeng;Shujing Jiang;Xiaoqing Chen
Journal of Separation Science 2015 Volume 38( Issue 9) pp:1476-1483
Publication Date(Web):
DOI:10.1002/jssc.201401458
An off-line two-dimensional high-speed counter-current chromatography method combined with gradient and recycling elution mode was established to isolate terpenoids and flavones from the leaves of Andrographis paniculata (Burm. f.) Nees. By using the solvent systems composed of n-hexane/ethyl acetate/methanol/water with different volume ratios, five compounds including roseooside, 5,4′-dihydroxyflavonoid-7-O-β-d-pyranglucuronatebutylester, 7,8-dimethoxy-2′-hydroxy-5-O-β-d-glucopyranosyloxyflavon, 14-deoxyandrographiside, and andrographolide were successfully isolated. Purities of these isolated compounds were all over 95% as determined by high-performance liquid chromatography. Their structures were identified by UV, mass spectrometry, and 1H NMR spectroscopy. It has been demonstrated that the combination of off-line two-dimensional high-speed counter-current chromatography with different elution modes is an efficient technique to isolate compounds from complex natural product extracts.
Co-reporter:Zhi-Liang Wu;Qi Liu;Jin-Gang Yu
Journal of Separation Science 2015 Volume 38( Issue 19) pp:3404-3411
Publication Date(Web):
DOI:10.1002/jssc.201500246
A convenient and accurate analysis approach that combined solid-phase extraction and high-performance liquid chromatography was developed to determine the amount of Rhodamine B in red wine and Xiang-jiang river water samples. A novel composite, magnesium hydroxide/carbon nanotube composites, was synthesized and used as the solid-phase extractant for the preconcentration/analysis of Rhodamine B. Magnesium hydroxide/carbon nanotube composites, which combined the merits of carbon nanotubes and magnesium hydroxide, exhibited acceptable adsorption and desorption efficiencies for Rhodamine B. The linear range of the proposed solid-phase extraction with high-performance liquid chromatography method for Rhodamine B was 0.05–20.0 mg/L, with a limit of detection of 3.6 μg/L. The precision and reproducibility of the developed solid-phase extraction with high-performance liquid chromatography method and the batch-to-batch reproducibility of the solid-phase extractant were also validated at spiking levels of 0.5 and 2.0 mg/L. The recovery of Rhodamine B was 94.33–106.7%, and the recovery relative standard deviations of the intra- and interday precisions were ≤ 3.83 and ≤ 6.01%, respectively. The relative standard deviation of the batch-to-batch reproducibility was ≤ 7.98%.
Co-reporter:Hualiang Zeng;Qi Liu;Jingang Yu;Meiling Wang;Miao Chen;Ranhao Wang;Xi He;Menghuan Gao;Xiaoqing Chen
Journal of Separation Science 2015 Volume 38( Issue 22) pp:3897-3904
Publication Date(Web):
DOI:10.1002/jssc.201500824
In this study, an on-line two-dimensional high-speed counter-current chromatography system based on a six-port valve was developed. Target-guided by ultrafiltration with high-performance liquid chromatography, the one-step isolation of three potential α-amylase inhibitors from Abelmoschus esculentus (L).Moench was achieved by employing the developed orthogonal system and extrusion elution mode. The purities of three potential α-amylase inhibitors were all over 95% as determined by high-performance liquid chromatography. Furthermore, UV, mass spectrometry and 1H NMR spectroscopy were applied to the structural identification of the isolated three target compounds, their structures were assigned as quercetin-3-O-sophoroside (i), 5,7,3′,4′-tetrahydroxy flavonol-3-O-[β-d-rhamnopyranosil-(12)]-β-d-glucopyranoside (ii ) and isoquercitrin (iii), respectively. The Results demonstrated that the proposed method was highly efficient to screen and isolate enzyme inhibitors from complex natural products extracts, and on-line two-dimensional high-speed counter-current chromatography can effectively increase the peak resolution of target compounds.
Co-reporter:Miao Chen, Liya Rong and Xiaoqing Chen
RSC Advances 2015 vol. 5(Issue 125) pp:103557-103562
Publication Date(Web):26 Nov 2015
DOI:10.1039/C5RA24162F
It is well known that Cu(II) can coordinate with L-alanine (Cu–Ala), which can be destroyed through the addition of glutamic-pyruvic transaminase (GPT) since GPT can effectively catalyze the conversion of L-alanine into keto-acetic acid. As a result, the free Cu(II) ion can combine with bovine serum albumin (BSA) and in turn quench the fluorescence of BSA. In this context, a simple and sensitive GPT activity detection via fluorescence quenching method has been developed. The fluorescence intensity of the system shows a linear relationship with the GPT concentration in the range of 5 and 400 U L−1 with a detection limit down to 3 U L−1 (S/N = 3). Avoiding any labels or complicated operations, this cost-effective and convenient method holds the potential for the rapid diagnosis of GPT-related diseases.
Co-reporter:Lin-Yan Yu, Qi Liu, Xiong-Wei Wu, Xin-Yu Jiang, Jin-Gang Yu and Xiao-Qing Chen
RSC Advances 2015 vol. 5(Issue 119) pp:98020-98025
Publication Date(Web):05 Nov 2015
DOI:10.1039/C5RA20082B
A multi-walled carbon nanotube–chitosan composite modified glassy carbon electrode (MWCNT–CS/GCE) was prepared and used for the chiral recognition of tryptophan (Trp) enantiomers. Cyclic voltammetry (CV) was employed to characterize the electrical conductivity of the modified electrode. Differential-pulse voltammetry (DPV) was employed to observe the oxidation peak potentials (Ep) of L- and D-Trp at the modified electrode. Different Ep of L- and D-Trp at the modified GCE were observed in the solutions containing only L- or D-Trp enantiomers. As for a mixed aqueous solution containing both L- and D-Trp, only one Ep peak would appear. However, the Ep of the peak was found to shift positively and linearly with an increasing percentage of L-isomer in the racemic Trp mixture solution, making it possible to determine the percentage of L- and D-Trp enantiomers in a racemic Trp mixture.
Co-reporter:Yi-min Dai 戴益民;Hui Liu 刘辉 陈晓青
Journal of Central South University 2015 Volume 22( Issue 1) pp:30-36
Publication Date(Web):2015 January
DOI:10.1007/s11771-015-2491-0
Flash point is a primary property used to determine the fire and explosion hazards of a liquid. New group contribution-based models were presented for estimation of the flash point of alkanes by the use of multiple linear regression (MLR) and artificial neural network (ANN). This simple linear model shows a low average relative deviation (AARD) of 2.8% for a data set including 50 (40 for training set and 10 for validation set) flash points. Furthermore, the predictive ability of the model was evaluated using LOO cross validation. The results demonstrate ANN model is clearly superior both in fitness and in prediction performance. ANN model has only the average absolute deviation of 2.9 K and the average relative deviation of 0.72%.
Co-reporter:Xiu-Hui Zhao, Fei-Peng Jiao, Jin-Gang Yu, Yang Xi, Xin-Yu Jiang, Xiao-Qing Chen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 476() pp:35-41
Publication Date(Web):5 July 2015
DOI:10.1016/j.colsurfa.2015.03.016
•TA-modified MWCNT (MWCNT-TA) was prepared.•The adsorption properties of MWCNT-TA for Cu(II) were studied.•The adsorption conditions were optimized.Take full advantage of the high adsorption capability of tartaric acid (TA) and high stability of multi-walled carbon nanotubes (MWCNTs) in organic/inorganic solvents, TA modified MWCNT (MWCNT-TA) was prepared and its adsorption properties for bivalent copper ion [Cu(II)] were studied. The MWCNT-TA composites were confirmed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). And the surface area of MWCNT-TA was determined by the Brunauer–Emmett–Teller (BET) method. The removal capacity of MWCNT-TA for Cu(II) was further investigated. In order to optimize the adsorption conditions, batch adsorption experiments were performed, and some factors that affecting the adsorption process including initial Cu(II) concentration, pH, contact time, and temperature were investigated. The adsorption kinetics could be better described by the pseudo second-order model, and the adsorption matches with the Langmuir isotherm. The results indicated that MWCNT-TA possessed higher adsorption capability for Cu(II) than pristine MWCNTs and TA. Additionally, MWCNT-TA can be facilely separated from aqueous solution by centrifugation and filtration after adsorption of Cu(II). Therefore, MWCNT-TA would find its potential application in wastewater treatment in the future.Tartaric acid (TA) modified multi-walled carbon nanotube (MWCNT-TA) was prepared and its adsorption properties for bivalent copper ion [Cu(II)] were studied. The MWCNT-TA composites were confirmed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). And the surface area of MWCNT-TA was determined by the Brunauer–Emmett–Teller (BET) method. The removal capacity of MWCNT-TA for Cu(II) was further investigated. Batch adsorption experiments were performed to optimize the conditions, and some factors that affecting the adsorption process, including initial pH, dosage of adsorbent, contact time, and temperature were investigated. The adsorption kinetics could be better described by the pseudo second-order model, and the adsorption matches with the Langmuir isotherm. The results indicated that MWCNT-TA possessed higher adsorption capability for Cu(II) than pristine MWCNTs or TA.
Co-reporter:Dongxue Wang, Liangliang Liu, Xinyu Jiang, Jingang Yu, Xiaoqing Chen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 466() pp:166-173
Publication Date(Web):5 February 2015
DOI:10.1016/j.colsurfa.2014.11.021
•Fe3O4/β-CD/GO show maximum adsorption capacity was 740.74 mg/g at 25 °C and pH 7.•Fe3O4/β-CD/GO can be easily and fast extracted from water by magnetic attraction.•Removal rate of Fe3O4/β-CD/GO could reach 98% after three times of adsorption.•Adsorption capacity of Fe3O4/β-CD/GO remained at 80% after five cycles.Dye pollution has become one of the most important environmental issues. Simple and effective approaches aiming at the rapid removing of dye from environment were in demand. The magnetic β-cyclodextrin-graphene oxide nanocomposites (Fe3O4/β-CD/GO) were prepared as novel adsorbents. The composition and morphology of prepared materials were characterized by Fourier infrared spectrometry (FT-IR), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The Fe3O4/β-CD/GO nanocomposites were utilized in the adsorptive removal of malachite green in aqueous solution. The factors such as adsorption time, adsorption temperature, pH of solution, adsorption kinetics and isotherms were investigated. The results indicated that the Fe3O4/β-CD/GO nanocomposites had good adsorption ability and the maximum adsorption capacity was 990.10 mg/g at 45 °C and pH 7. The adsorption capacity remained at 80% after five cycles. Removal rate could reach 98% after three times of adsorption. The adsorption process with malachite green was found that fitted pseudo second order kinetics equations and the Langmuir adsorption model. In addition, the thermodynamic was investigated to indicate that the adsorption process was spontaneous and endothermic in nature. The experimental results showed the Fe3O4/β-CD/GO nanocomposites had a good adsorption ability to remove dyes in wastewater and can be rapidly extracted from water.
Co-reporter:Jun Wang;Xiaoqing Chen;Feipeng Jiao
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2015 Volume 81( Issue 3-4) pp:475-484
Publication Date(Web):2015 April
DOI:10.1007/s10847-015-0477-z
In the study herein we focused on enantioseparation of phenylsuccinic acid (PSA) enantiomers using an aqueous two-phase system (ATPS) composed of ethanol and ammonium sulfate. Based on phase-forming points and salting-out points, a modified phase diagram of ethanol/ammonium sulfate system with three distinct phase areas, including homogeneous area, ATPS area and salting-out area, has been constructed experimentally. The ATPS optimization and evaluation of chiral separation efficiency for PSA enantiomers have been investigated thoroughly. A hydrophilic chiral selector, hydroxypropyl-β-cyclodextrin (HP-β-CD), which has good chiral recognition ability for R-PSA, was added into bottom phase. The chiral separation efficiencies, namely distribution coefficients and separation factor, were affected by various process variables, including phase compositions of ATPS, concentrations of HP-β-CD and PSA enantiomers, pH value and operational temperature. Under the optimum conditions, separation factor could reach 1.42 after just one step extraction. This environmentally benign chiral separation technique opens up new possibilities for preparative separation of other racemic compounds at a large-scale.
Co-reporter:Hualiang Zeng, Qi Liu, Meiling Wang, Shujing Jiang, Li Zhang, Xi He, Jun Wang, Xiaoqing Chen
Journal of Chromatography B 2015 Volume 1001() pp:58-65
Publication Date(Web):15 September 2015
DOI:10.1016/j.jchromb.2015.07.046
Co-reporter:Hualiang Zeng, Qi Liu, Jingang Yu, Xinyu Jiang, Zhiliang Wu, Meiling Wang, Miao Chen, Xiaoqing Chen
Journal of Chromatography B 2015 Volume 1004() pp:10-16
Publication Date(Web):1 November 2015
DOI:10.1016/j.jchromb.2015.09.017
•A tandem HSCCC separation system was first developed based on a six-port valve.•Nine structural analogous including three isomers were isolated via tandem HSCCC.•All separated compounds were separated by CCC from PC for the first time.•Compound 9 with high retention ability was obtained by adopting extrusion elution.A novel one-step separation strategy—tandem high-speed counter-current chromatography (HSCCC) was developed with a six-port valve serving as the switch interface. Nine structural analogues including three isomers were successfully isolated from Poria cocos (Schw.) Wolf. by one step. Compared with conventional HSCCC, peak resolution of target compounds was effectively improved in tandem one. Purities of isolated compounds were all over 90% as determined by HPLC. Their structures were then identified via UV, MS and 1H NMR, and eventually assigned as poricoic acid B (1), poricoic acid A (2), 3β,16α-dihydroxylanosta-7, 9(11), 24-trien-21-oic acid (3), dehydrotumulosic acid (4), polyporenic acid C (5), 3-epi-dehydrotumulosic acid (6), 3-o-acetyl-16α-hydroxydehydrotrametenolic acid (7), dehydropachymic acid (8) and dehydrotrametenolic acid (9) respectively. The results indicated that tandem HSCCC can effectively improve peak resolution of target compounds, and can be a good candidate for HSCCC separation of structural analogues.
Co-reporter:Liangliang Liu, Yin Cen, Fang Liu, Jingang Yu, Xinyu Jiang, Xiaoqing Chen
Journal of Chromatography B 2015 Volumes 995–996() pp:64-69
Publication Date(Web):15 July 2015
DOI:10.1016/j.jchromb.2015.05.016
•The MCLEAs of α-amylase was first utilized in screening of α-amylase inhibitors.•The MCLEAs of α-amylase showed good reusability in the screening experiment.•The α-amylase inhibitor in corni fructus was screened as querciturone.As a carrier-free immobilization strategy, magnetic cross-linked enzyme aggregates (MCLEAs) showed improved enzyme activity, stability and magnetic response. In this study, MCLEAs of α-amylase (MCLEAs–amylase) was prepared under optimized conditions and characterized with scanning electron microscope and vibrating sample magnetometer. The prepared MCLEAs–amylase showed an amorphous structure and the saturation magnetization was 33.5 emu/g, which was sufficient for magnetic separation. Then MCLEAs–amylase coupled with high performance liquid chromatography–mass spectrometry (HPLC–MS) was utilized to screen and identify α-amylase inhibitors from ethyl acetate extract of corni fructus. The experiment conditions were optimized. At the optimum conditions (incubation time: 10 min, pH: 7.0 and temperature: 20 °C), querciturone was successfully screened and identified with weak non-specific binding. The screening result was verified by inhibition assays and the IC50 value of querciturone was 22.5 μg/mL. This method provided a rapid way to screen active compounds from natural products.
Co-reporter:Zhi-Liang Wu, Hua Yang, Fei-Peng Jiao, Qi Liu, Xiao-Qing Chen, Jin-Gang Yu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 470() pp: 149-160
Publication Date(Web):
DOI:10.1016/j.colsurfa.2015.01.069
Co-reporter:Guobao Zhou, Meihua Lin, Ping Song, Xiaoqing Chen, Jie Chao, Lianhui Wang, Qing Huang, Wei Huang, Chunhai Fan, and Xiaolei Zuo
Analytical Chemistry 2014 Volume 86(Issue 15) pp:7843
Publication Date(Web):July 3, 2014
DOI:10.1021/ac502276w
Sensitive detection of cancer cells plays a critically important role in the early detection of cancer and cancer metastasis. However, because circulating tumor cells are extremely rare in peripheral blood, the detection of cancer cells with high analytical sensitivity and specificity remains challenging. Here, we have demonstrated a simple, sensitive and specific detection of cancer cells with the detection sensitivity of four cancer cells, which is lower than the cutoff value with respect to correlation with survival outcomes as well as predictive of metastatic disease in clinical diagnostics. We re-engineered the hybridization chain reaction (HCR) to multibranched HCR (mHCR) that can produce long products with multiple biotins for signal amplification and multiple branched arms for multivalent binding. The capturing gold surface is modified with DNA tetrahedral probes, which provide superior hybridization conditions for the multivalent binding. The synergetic effect of mHCR amplification and multivalent binding lead to the high sensitivity of our detection platform.
Co-reporter:Qi Liu, Junan Xiao, Jingang Yu, Yixi Xie, Xiaoqing Chen, Hua Yang
Journal of Chromatography A 2014 Volume 1363() pp:236-241
Publication Date(Web):10 October 2014
DOI:10.1016/j.chroma.2014.07.040
•Twin-column R-HPLC was used for improving enantioseparation for the first time.•Experimental comparison of two R-HPLC methods was reported for the first time.•Performance of two R-HPLC methods was evaluated on the enantioseperation.•Intractable four stereoisomers of isoxazolidines were separated by baseline.A long-neglected recycling high performance liquid chromatography (R-HPLC) strategy was adopted to improve the enantioseparation efficiency in this work. Taking intractable isoxazolidine mixtures as the example, two different R-HPLC methods including single-column and twin-column based strategy were applied to improve the enantioseparation efficiency. Under the optimized conditions, these two methods present distinct separation results: the conceptually simple and commonly used single-column based R-HPLC led to severe peak broadening and degraded separation efficiency; on the contrary, the enantioseparation was significantly improved by adopting the relatively complicated twin-column strategy. This observed difference might be mainly attributed to less peak spreading and sample mixing of the latter, as a result of avoiding redirecting the effluent back to LC pump.
Co-reporter:Qi Liu, Jianda Zhou, Jingang Yu, Yixi Xie, Xinyu Jiang, Hua Yang, Xiaoqing Chen
Journal of Chromatography A 2014 Volume 1364() pp:204-213
Publication Date(Web):17 October 2014
DOI:10.1016/j.chroma.2014.08.087
•A CCC–SPE–CCC system was developed.•Trapping conditions of SPE were optimized.•Five intractable compounds were separated by baseline through adopting recycling CCC.•11 compounds with large polarity difference were separated by running CCC only once.A counter-current chromatography (CCC)–solid phase extraction (SPE)–CCC system with high preparative capacity was used to realize rapid one-run systematic separation of natural products, in which two six-port valves and the SPE cartridge served as the interface. In the orthogonal separation system, equal column volumes of TEB-300A and TEB-300B were employed for the first dimension (1st-D) and second dimension (2nd-D), respectively. An optimized solid-phase column (25 mm × 10 mm i.d.) packed with Oasis HLB materials acted as the trapping SPE column. The analyte-focusing effect of the trapping column associated with the considerable preparative capacities of 1st-D and 2nd-D using totally different solvent systems significantly facilitated this one-run systematic separation of natural product. Therefore, this proposed approach was successfully applied to isolate chemical compounds from the crude extract of Rhizoma Chuanxiong. As a result, 11 compounds with widely different polarities were separated by running CCC for only one time. More importantly, this hyphenated strategy could serve as a rapid and efficient systematic pathway for the separation of natural products.
Co-reporter:Miao Chen;Liangliang Liu;Xiaoqing Chen
Journal of Separation Science 2014 Volume 37( Issue 13) pp:1546-1551
Publication Date(Web):
DOI:10.1002/jssc.201400051
A simple, rapid, and effective assay based on ultrafiltration combined with high-performance liquid chromatography and high-speed countercurrent chromatography was developed for screening and purifying alcohol dehydrogenase inhibitors from Glycyrrhiza uralensis root extract. Experiments were carried out to optimize binding conditions including alcohol dehydrogenase concentration, incubation time, temperature, and pH. By comparing the chromatograms, three compounds were found possessing alcohol dehydrogenase binding activity in Glycyrrhiza uralensis root. Under the target-guidance of ultrafiltration combined with the high-performance liquid chromatography experiment, liquiritin (1), isoliquiritin (2), and liquiritigenin (3) were separated by high-speed countercurrent chromatography using ethyl acetate/methanol/water (5:1:4) as the solvent system. The alcohol dehydrogenase inhibitory activities of these three isolated compounds were assessed; compound 2 showed strongest inhibitory activity with an IC50 of 8.95 μM. The results of the present study indicated that the combinative method using ultrafiltration, high-performance liquid chromatography and high-speed countercurrent chromatography could be widely applied for the rapid screening and isolation of enzyme inhibitors from complex mixtures.
Co-reporter:Liangliang Liu, Shuyun Shi, Huading Zhao, Jingang Yu, Xinyu Jiang, Xiaoqing Chen
Journal of Chromatography B 2014 Volumes 945–946() pp:163-170
Publication Date(Web):15 January 2014
DOI:10.1016/j.jchromb.2013.11.053
Xanthine oxidase (XOD) immobilized core–shell magnetic silica (Fe3O4@SiO2-XOD) nanoparticles coupled with high performance liquid chromatography–mass spectrometry (HPLC–MS) was developed to fish out and analyze XOD binders from two Fabaceae species, Puerariae lobata flower and Glycyrrhiza uralensis root. The prepared Fe3O4@SiO2-XOD nanoparticles exhibited good specificity for XOD binders, better dispersion in aqueous solution and reusability than those of Fe3O4-XOD nanoparticles. The amount of XOD immobilized onto Fe3O4@SiO2 nanoparticles was 339.9 μg/mg and the activity of Fe3O4@SiO2-XOD nanoparticles remained 95% after ten times usage. The optimum conditions of selective fishing were optimized, and finally incubating pH was set at 7, incubating temperature at 25 °C and adsorption time at 30 min. Twelve XOD binders were successfully identified from ethyl acetate extract of P. lobata flower and G. uralensis root. The developed method provides a rapid, purposeful and effective way to identify active compounds from natural complex mixtures.
Co-reporter:Qi Liu, Shuyun Shi, Liangliang Liu, Hua Yang, Wen Su, Xiaoqing Chen
Journal of Chromatography A 2013 Volume 1304() pp:183-193
Publication Date(Web):23 August 2013
DOI:10.1016/j.chroma.2013.07.043
•(BSA-Fe3O4MNPs)-HPLC–MS/MS was developed to screen bioactive compounds from Fructus polygoni orientalis.•Off-line 2D HSCCC with several operation modes including Recycling HSCCC, Normal-Phase HSCCC and Reverse-Phase HSCCC was used to isolate target compounds.•Copper ion as a complexation agent was introduced into HSCCC two-phase solvent systems.•Complexation HSCCC behavior of seven compounds was explained by investigating their chelating power with copper ion.In this study, off-line two-dimensional (2D) complexation high speed counter-current chromatography (HSCCC) was developed for the separation of bovine serum albumin (BSA) binders from the ethyl acetate extract of Fructus polygoni orientalis. Target-guided strategy of BSA functionalized iron oxide magnetic nanoparticles coupled with high performance liquid chromatography–tandem mass spectrometry ((BSA-Fe3O4 MNPs)-HPLC–MS/MS) experiment was proposed. In the orthogonal separation system, a Normal-Phase HSCCC with 0.01 mol/L copper ion as complexation agent in the aqueous phase was employed for the first dimension and Recycling HSCCC, Reverse-Phase HSCCC with 0.1 mol/L copper ion were used for the second dimension in parallel. Including two pairs of cis-trans isomers, seven BSA binders including 3,5,7-Trihydroxychromone (1), taxifolin (2), N-cis-paprazine (3), N-cis-feruloyltyramine (4), N-trans-paprazine (5), N-trans-feruloyltyramine (6) and an unidentified compound (7) were obtained. The purities of these seven compounds were all over 95.0% as determined by HPLC. The complexation HSCCC behaviors of seven compounds were also investigated by studying their relationship with copper ion. Results showed that the combinative method using (BSA-Fe3O4 MNPs)-HPLC and HSCCC is a quick, efficient, and reproductive technique to isolate potentially bioactive compounds from the complex mixture system of natural products. And the usage of off-line 2D-HSCCC and introduction of chelating metal ion into solvent system are effective ways to implement HSCCC separations in complex samples.
Co-reporter:Qi Liu;Xinyu Jiang;Haixing Zheng;Wen Su;Xiaoqing Chen;Hua Yang
Journal of Separation Science 2013 Volume 36( Issue 19) pp:3158-3164
Publication Date(Web):
DOI:10.1002/jssc.201300412
A novel LC-based method for the determination of enantiomeric excess (ee) in a sample mixture has been developed by employing on-line 2D LC. The orthogonal separation system is composed of an NH2 column as the first dimension to elute the target chiral compound from the crude mixture and a chiral column as the second dimension to determine the ee of the target chiral product. A series of crude mixtures from asymmetric reactions have been directly analyzed without prepurification. Good reproducibility (intra- and interday precisions were all under 1.33%) and good accuracy (deviations from ee values determined by 1D HPLC were all <1.03%) have been obtained. Compared with the traditional method for the determination of ee, on-line 2D HPLC can be used in real time and holds great potential in the time-saving determination of ee in asymmetric synthesis.
Co-reporter:Wen Su;Qi Liu;Qing Yang;Jingang Yu;Xiaoqing Chen
Journal of Separation Science 2013 Volume 36( Issue 20) pp:3338-3344
Publication Date(Web):
DOI:10.1002/jssc.201300653
An off-line 2D high-speed counter-current chromatography technique in preparative scale has been successfully applied to separate and purify the main compounds from the ethyl acetate extract of Desmodium styracifolium. A two-phase solvent system composed of n-hexane/ethyl acetate/methanol/water at an optimized volume ratio of 1:2:1:2 v/v/v/v was used. Conventional high-speed counter-current chromatography was used as the first dimension, and the upper phase of the solvent system was used as the stationary phase in the head-to-tail elution mode at a flow rate of 2.0 mL/min and a rotation speed of 900 rpm. Recycling high-speed counter-current chromatography served as the second dimension to separate an impure fraction of the first dimension. A total of four well-separated substances including vanillic acid (1), β-sitosterol (2), formononetin (3), and aromadendrin (4) were obtained, and their purities and structures were identified by HPLC–MS and 1H NMR spectroscopy. The results illustrated that off-line 2D high-speed counter-current chromatography is an effective way to isolate compounds in complex samples.
Co-reporter:Guobao Zhou, Xiangwen Liu, Caiyun Nan, Yunxin Liu, Dingsheng Wang and Xiaoqing Chen
New Journal of Chemistry 2013 vol. 37(Issue 8) pp:2582-2588
Publication Date(Web):15 May 2013
DOI:10.1039/C3NJ00003F
Uniformly carbonaceous and nitrogenous species sensitized TiO2 quantum dots (QDs, ∼4 nm) were synthesized through an improved strategy employing an oleic acid and oleylamine system, and were further assembled into the mesoporous structure of C/N-TiO2 nanospheres via an emulsion-based bottom-up self-assembly (EBS). EBS not only transformed oil-soluble C/N-TiO2 QDs into water-soluble nanospheres, but also assembled them into mesostructures with an average diameter around 200 nm. The photocatalytic properties of the as-prepared C/N-TiO2 QDs and C/N-TiO2 nanospheres were evaluated by measuring the photodegradation of rhodamine B (RhB) under visible-light irradiation. Compared to C/N-TiO2 QDs and commercial product P25, the experimental results showed that the water miscible mesostructured C/N-TiO2 nanospheres with improved effective catalytic area and RhB adsorption, and a red shift of the absorption edge to the visible light region, possessed improved photocatalytic activity. The purpose of this study is to illustrate the importance of C/N-species sensitization and fundamental structural control in effecting the photodegradation property of TiO2-based catalysts.
Co-reporter:Shaolong Du, Yixi Xie and Xiaoqing Chen
Molecular BioSystems 2013 vol. 9(Issue 1) pp:55-60
Publication Date(Web):10 Oct 2012
DOI:10.1039/C2MB25351H
High levels of glucose in diabetics can react with plasma proteins through a non-enzymatic process. Herein, the influence of glucose on the interaction between flavones and human serum albumin (HSA) was investigated, as well as the effect of glucose on the antioxidant potential of a flavone–HSA system. It looks like the interactions of HSA and flavones with more hydroxyl groups on ring A are more easily affected by glucose. Flavones act as hydrogen bond donors with HSA by means of interacting with glucose. With increased incubation time in air (from 1 to 23 days), the affinities of HSA for multi-hydroxyl flavones on ring A were obviously higher than for non- or mono-hydroxyl flavones on ring A. HSA significantly masked the DPPH radical scavenging potential of 7,8-dihydroxyflavone and baicalein. However, glucose obviously enhances the DPPH scavenging potential of a baicalein–HSA system. Moreover, glucose slightly weakens the DPPH scavenging potential of a 7,8-dihydroxyflavone–HSA system.
Co-reporter:Qing Yang;Xiaoqing Chen;Xinyu Jiang
Chromatographia 2013 Volume 76( Issue 23-24) pp:1641-1647
Publication Date(Web):2013 December
DOI:10.1007/s10337-013-2554-z
A novel, efficient, and environmentally friendly method—supramolecular solvent liquid–liquid microextraction (SMS-LLME) combined with high-performance liquid chromatography (HPLC)—was first established for the determination of p-nitrophenol and o-nitrophenol in water samples. Several important parameters influencing extraction efficiency, such as the type and volume of extraction solvent, pH of sample, temperature, salt effect, extraction time, and stirring rate, were optimized in detail. Under the optimal conditions, the enrichment factor was 166 for p-nitrophenol and 160 for o-nitrophenol, and the limits of detection by HPLC were 0.26 and 0.58 μg L−1, respectively. Excellent linearity with coefficients of correlation from 0.9996 to 0.9997 was observed in the concentration range of 2–1,000 μg L−1. The ranges of intra- and interday precision (n = 5) at 100 μg L−1 of nitrophenols were 5.85–7.76 and 10.2–11.9 %, respectively. The SMS-LLME method was successfully applied for preconcentration of nitrophenols in environmental water samples.
Co-reporter:Liangliang Liu, Shuyun Shi, Xiaoqing Chen, Mijun Peng
Journal of Chromatography B 2013 Volume 932() pp:19-25
Publication Date(Web):1 August 2013
DOI:10.1016/j.jchromb.2013.06.002
Tyrosinase inhibitors play an important role in cosmetic products, food supplements and medicinal industries. In this study, a new facile method based on tyrosinase immobilized magnetic fishing (IMF) coupled with high performance liquid chromatography–diode array detector–tandem mass spectrometry (HPLC–DAD–MS/MS) was developed to screen and identify tyrosinase binders from Glycyrrhiza uralensis root. Experiments were carried out to select optimal immobilization and incubation conditions. The activity of immobilized tyrosinase retained 76.3% after ten consecutive cycles, and remained over 95% when stored at 4 °C for about two months. Eleven tyrosinase binders, including original compounds and transformation products were successfully screened and characterized from G. uralensis root, while dihydrodaidzein and pratensein were reported for the first time. Compared with ultrafiltration-HPLC assay, IMF-HPLC displayed many attractive advantages, including convenient solid–liquid separation ability, good stability, high reusability and activity, which indicated that IMF-HPLC had a broad applicability. The results indicated that IMF-HPLC method is a facile, effective and reproductive way to screen and identify active components from complex mixtures.
Co-reporter:Liangliang Liu, Yongjian Ma, Xiaoqing Chen, Xiang Xiong, Shuyun Shi
Journal of Chromatography B 2012 Volumes 887–888() pp:55-60
Publication Date(Web):1 March 2012
DOI:10.1016/j.jchromb.2012.01.008
Puerariae lobata flower (Willdenow) has a long history used to treat alcoholic intoxication in China, which contains a series of isoflavones as its chief pharmacologically active constituents. In this study, bovine serum albumin (BSA) functionalized iron oxide magnetic nanoparticles (Fe3O4 MNPs) coupled with high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) were used to screen and identify active compounds from ethanolic extract of P. lobata flower. Thirteen active isoflavones were screened and identified as glycitin (1), tectoridin (2), daidzin (3), 3′-methoxy daidzin (4), ononin (5), 3′-hydroxyl daidzein (6), tectorigenin (7), biochanin A (8), prunetin (9), genistein (10), 3′-methoxy daidzein (11), irisolidone (12) and 5,7-dihydroxy-3′,4′-methylenedioxyisoflavone (13), while compounds 4, 6, 9, 11 and 13 were identified from this plant for the first time. Furthermore, the activity of each bound ligand was evaluated on-line. The results indicated that the binding affinities of compounds with BSA were highly dependent on chemical structures and the methoxylation and hydroxylation on B-ring could improve the activity. The effective method could be widely applied for rapid screening and identification of active compounds from complex mixtures.Highlights► A method was first used to screen and identify active compound in Puerariae lobata flower. ► Thirteen active compounds were identified. ► Five compounds were identified from P. lobata flower for the first time. ► The methoxylation and hydroxylation on B-ring could improve the activity.
Co-reporter:Feipeng Jiao;Weijie Yang;Fen Wang;Lingxing Tian;Lin Li;Xiaoqing Chen;Kelang Mu
Chirality 2012 Volume 24( Issue 8) pp:661-667
Publication Date(Web):
DOI:10.1002/chir.22067
ABSTRACT
A method of solvent sublation was developed for the enantioseparation of racemic ofloxacin (rac Oflx) and racemic tryptophan (rac Trp). In this method, dibenzoyl-L-tartaric acid (L-DBTA) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) and sodium lauryl sulfate (SDS) were used as chiral coextractants and foamer, respectively. Several important parameters influencing the separation performances, such as pH in aqueous phase, concentrations of rac mixtures, L-DBTA, D2EHPA, and SDS, were investigated. Under the optimal operation conditions, the enantiomeric excess and enantioselectivity were 60.08% and 5.58 for Oflx and 65.09% and 6.31 for Trp, respectively. The yields of D-enantiomer and L-enantiomer were 34.23% and 8.54% for Oflx and 18.59% and 3.93% for Trp, respectively. The results suggest that the enantioselectivities have been enhanced compared with the traditional chiral extraction. This technique is an efficient chiral separation method, with many advantages such as low expenditures of organic solvent, low consumption of chiral extractant, and easy realization of multistage operation. Chirality 24:661-667, 2012. © 2012 Wiley Periodicals, Inc.
Co-reporter:Feipeng Jiao, Jingang Yu, Hailei Song, Xinyu Jiang, Hua Yang, Shuyun Shi, Xiaoqing Chen, Weijie Yang
Applied Clay Science (November 2014) Volume 101() pp:30-37
Publication Date(Web):November 2014
DOI:10.1016/j.clay.2014.07.006
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