Xun Liao

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Organization: Chengdu Institute of Biology

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Material Chemistry

Carbon Nanotubes

Chemicals
References

Functionalized carbon quantum dots with dopamine for tyrosinase activity analysis

Co-reporter:Jin-Jie Hu, Xiao-Lin Bai, Yi-Ming Liu, Xun Liao

Analytica Chimica Acta 2017 Volume 995(Volume 995) pp:

Publication Date(Web):1 December 2017

DOI:10.1016/j.aca.2017.09.038

•CQDs-Dopa was synthesized by a simple one-pot hydrothermal method.•A sensitive, practical and selective assay for TYR has been well established.•The synthesized CQDs-Dopa used for TYR analysis covers two broad ranges and a low detection limit.Tyrosinase (TYR) is a key enzyme in melanin biosynthesis and its activity is an important biomarker for dermatological disorders, such as vitiligo, melanoma and actinic damages. Sensitive assay for TYR activity is significant for basic and clinical research. In this work, a facile fluorescent assay for TYR activity based on dopamine functionalized carbon quantum dots (CQDs-Dopa) has been developed. Dopamine (Dopa) was covalently bond to CQDs through a simple one-pot hydrothermal method, and the prepared CQDs-Dopa exhibited a fluorescence emission at 499 nm under exciting wavelength at 310 nm with a quantum yield of approximately 2.1%. When TYR was mixed with CODs-Dopa, the dopamine moiety in CQDs-Dopa conjugate was oxidized to O-dopaquinone, and an intra-particle photo-induced electron transfer (PET) process consequently occurred between CQDs and O-dopaquinone to quench the fluorescence of CQDs-Dopa. TYR activity can be determined based on the fluorescence quenching degree of CQDs-Dopa. This assay covered two broad linear ranges: 44.4–711.1 U L−1 and 711.1–2925.4 U L−1, with detection limit of 17.7 U L−1. The proposed fluorescent assay was applied to TYR activity measurement in human serum samples. It showed promising potential for TYR activity assay in clinical applications.Download high-res image (195KB)Download full-size image

PEGylation of magnetic multi-walled carbon nanotubes for enhanced selectivity of dispersive solid phase extraction

Co-reporter:Qiong Zeng, Yi-Ming Liu, Yan-Wei Jia, Li-Hong Wan, Xun Liao

Materials Science and Engineering: C 2017 Volume 71() pp:186-194

Publication Date(Web):1 February 2017

DOI:10.1016/j.msec.2016.09.082

•PEGylation of CNTs-MNP result in novel nanocomposites with good water dispersibility.•PEG-CNTs-MNP evaluated as DSPE adsorbent for extraction of Z-ligustilide.•PEG-CNTs-MNP shows good selectivity in extracting Z-ligustilide from herbal extracts.•Quick DSPE method for isolating Z-ligustilide from herbal extracts established.Carbon nanotubes (CNTs) possess large potential as extraction absorbents in solid phase extraction. They have been widely applied in biomedicine research, while very rare application in natural product chemistry has been reported. In this work, methoxypolyethylene glycol amine (mPEG-NH2) is covalently coupled to CNTs-magnetic nanoparticles (CNTs-MNP) to prepare a novel magnetic nanocomposite (PEG-CNTs-MNP) for use as dispersive solid-phase extraction (DSPE) absorbent. The average particle size was 86 nm, and the saturation magnetization was 52.30 emu/g. This nanocomposite exhibits excellent dispersibility in aqueous systems, high selectivity and fast binding kinetics when used for extraction of Z-ligustilide, the characteristic bioactive compound from two popular Asian herbal plants, R. chuanxiong and R. ligusticum. HPLC quantification of Z-ligustilide extracted from the standard sample solution showed a high recovery of 98.9%, and the extraction rate from the extracts of the above two herbs are both around 70.0%. To our knowledge, this is the first report on using PEG-CNTs-MNP as DSPE nanosorbents for selective extraction of natural products. This nano-material has promising application in isolation and enrichment of targeted components from complex matrices.

Screening of lipase inhibitors from Scutellaria baicalensis extract using lipase immobilized on magnetic nanoparticles and study on the inhibitory mechanism

Co-reporter:Li-Hong Wan;Xiao-Lan Jiang;Yi-Ming Liu

Analytical and Bioanalytical Chemistry 2016 Volume 408( Issue 9) pp:2275-2283

Publication Date(Web):2016 March

DOI:10.1007/s00216-016-9320-7

Scutellaria baicalensis is a traditional Chinese medicinal plant possessing a wide variety of biological activities. In this work, lipase immobilized on magnetic nanoparticles (LMNPs) was used as solid phase extract absorbent for screening of lipase inhibitors from this plant. Three flavonoids were found to bind to LMNPs and were identified as baicalin, wogonin, and oroxylin A by liquid chromatography–mass spectrometry (HPLC-MS). Their IC50 values were determined to be 229.22 ± 12.67, 153.71 ± 9.21, and 56.07 ± 4.90 μM, respectively. Fluorescence spectroscopy and molecular docking were used to probe the interactions between these flavonoids and lipase. All the flavonoids quenched the fluorescence of lipase statically by forming new complexes, implying their affinities with the enzyme. The thermodynamic analysis suggested that van der Waals force and hydrogen bond were the main forces between wogonin and lipase, while hydrophobic force was the main force for the other two flavonoids. The results from a molecular docking study further revealed that all of them could insert into the pocket of lipase binding to a couple of amino acid residues.

Quick and selective extraction of Z-ligustilide from Angelica sinensis using magnetic multiwalled carbon nanotubes

Co-reporter:Qiong Zeng;Yan-Wei Jia;Pei-Li Xu;Meng-Wei Xiao;Yi-Ming Liu;Shu-Lin Peng

Journal of Separation Science 2015 Volume 38( Issue 24) pp:4269-4275

Publication Date(Web):

DOI:10.1002/jssc.201500862

A facile and highly efficient magnetic solid-phase extraction method has been developed for Z-ligustilide, the major therapeutic agent in Angelica sinensis. The solid-phase adsorbent material used was prepared by conjugating carbon nanotubes with magnetic Fe₃O₄ nanoparticles via a hydrothermal reaction. The magnetic material showed a high affinity toward Z-ligustilide due to the π–π stacking interaction between the carbon nanotubes and Z-ligustilide, allowing a quick and selective exaction of Z-ligustilide from complex sample matrices. Factors influencing the magnetic solid-phase extraction such as the amount of the added adsorbent, adsorption and desorption time, and desorption solvent, were investigated. Due to its high extraction efficiency, this method was proved highly useful for sample cleanup/enrichment in quantitative high-performance liquid chromatography analysis. The proposed method had a linear calibration curve (R² = 0.9983) over the concentration between 4 ng/mL and 200 μg/mL Z-ligustilide. The accuracy of the method was determined by the recovery, which was from 92.07 to 104.02%, with the relative standard deviations >4.51%.

Preparation of ds-DNA functionalized magnetic nanobaits for screening of bioactive compounds from medicinal plant

Co-reporter:Li Yuan, Pei-Li Xu, Qiong Zeng, Yi-Ming Liu, Li-Sheng Ding, Xun Liao

Materials Science and Engineering: C 2015 Volume 56() pp:401-408

Publication Date(Web):1 November 2015

DOI:10.1016/j.msec.2015.06.050

•ds-DNA was directly immobilized onto magnetic nanobaits.•MNPs@DNA were characterized by CV, DPV, FT-IR, TGA and VSM.•A new method for screening ds-DNA binders was developed.•The binding ability of MNPs@DNA was studied.A novel magnetic nanocomposite (MNPs@DNA) was synthesized by bonding double strand DNA (ds-DNA) onto Fe3O4 magnetic nanoparticles (MNPs) directly. MNPs@DNA was characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV), Fourier transform infrared spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA), which indicated that ds-DNA was immobilized onto MNPs. Vibrating sample magnetometer (VSM) analysis indicated that the MNPs@DNA had a high saturation magnetization of 42.97 emu/g. A novel method for screening of active compounds from natural sources was developed by employing MNPs@DNA as a nanobait and high-performance liquid chromatography–mass spectrometry as detecting system. Columbamine, palmatine, jateorhizine, epiberberine and berberine were identified as DNA binders from the extract of Rhizoma coptidis. In addition, a comparison of the binding abilities among MNPs with different DNA strand lengths (25, 200 and 1200 bp) showed that the shortest one exhibited the highest binding ability. This is the first report on fast chemical characterization of active ingredients in medicinal plant using ds-DNA immobilized on magnetic nano-baits. This method can be used not only for screening of DNA binders from complex herbal matrices, but also for assessing the affinities between a specific ds-DNA and its potential binders.

Selective extraction of berberine from Cortex Phellodendri using polydopamine-coated magnetic nanoparticles

Co-reporter:Hai-Li Shi;Shu-Lin Peng;Jun Sun;Yi-Ming Liu;Yuan-Ting Zhu;Lin-Sen Qing

Journal of Separation Science 2014 Volume 37( Issue 6) pp:704-710

Publication Date(Web):

DOI:10.1002/jssc.201301294

A new extraction agent featuring dopamine self-polymerized on magnetic Fe₃O₄ nanoparticles has been successfully synthesized and evaluated for the SPE of berberine from the extract of the traditional Chinese medicinal plant, Cortex Phellodendri. The nanoparticles prepared possessed a core–shell structure and showed super-paramagnetism. It was found that these polydopamine-coated nanoparticles exhibited strong and selective adsorption for berberine. Among the chemical components present in C. Phellodendri, only berberine was adsorbed by the nanoparticles and extracted by a following SPE procedure. Various conditions such as the amount of polydopamine-coated nanoparticles, desorption solvent, desorption time and equilibrium time were optimized for the SPE of berberine. The purity of berberine extracted from C. Phellodendri was determined to be as high as 91.3% compared with that of 9.5% in the extract. The established SPE protocol combined advantages of highly selective enrichment with easy magnetic separation, and proved to be a facile efficient procedure for the isolation of berberine. Further, the prepared polydopamine-coated magnetic nanoparticles could be reused for multiple times, reducing operational cost. The applicability and reliability of the developed SPE method were demonstrated by isolating berberine from three different C. Phellodendri extracts. Recoveries of 85.4–111.2% were obtained with relative standard deviations ranging from 0.27–2.05%.

Lipase Ligands in Nelumbo nucifera Leaves and Study of Their Binding Mechanism

Co-reporter:Yuan-Ting Zhu, Yan-Wei Jia, Yi-Ming Liu, Jian Liang, Li-Sheng Ding, and Xun Liao

Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 44) pp:10679-10686

Publication Date(Web):October 18, 2014

DOI:10.1021/jf503687e

Lotus (Nelumbo nucifera) leaves have been widely used in weight-loss foods to prevent obesity in China. In this work, a facile procedure based on ligand fishing was developed to isolate and identify lipase inhibitors present in lotus leaves. Highly stable and active lipase–Fe3O4 superparamagnetic nanoparticle conjugates (LMNPs) were prepared and used as baits. Two flavonoids in lotus leaf extract were found to bind to the baits and were identified as quercetin-3-O-β-d-arabinopyranosyl-(1→2)- β-d-galactopyranoside (1) and quercetin-3-O-β-d-glucuronide (4) based on electrospray ionization–mass spectrometric analyses. Their 50% inhibitory concentrations on lipase (IC50) were 52.9 ± 3.2 and 17.1 ± 1.5 μg/mL, respectively. In addition, they were found to significantly quench the fluorescence of lipase, suggesting their strong affinities with this enzyme, which was further evidenced by molecular docking. Ligand fishing based on LMNPs shows great power for fast screening and identification of lipase inhibitors present in edible and medicinal plants.

Panthogenins A and B, two novel norergostanol steroids from Dioscorea panthaica

Co-reporter:Xiao-Qing Shan, Shu-Lin Peng, Hai-Li Shi, Xiao-Ling Wang, Li-Sheng Ding, Xun Liao

Chinese Chemical Letters 2014 Volume 25(Issue 9) pp:1256-1258

Publication Date(Web):September 2014

DOI:10.1016/j.cclet.2014.04.004

Two novel 27-norergostanol steroids, panthogenins A (1) and B (2), possessing unusual rings E and F featuring a ketal moiety at C-25 were isolated from rhizomes of Dioscorea panthaica. Their structures and relative configurations were elucidated by extensive spectroscopic methods including 1D and 2D NMR techniques, and the structure of panthogenin A was further confirmed by X-ray crystallography. Both compounds showed potent in vitro insulin sensitizing activity.Two novel 27-norergostanol steroids were isolated from rhizomes of Dioscorea panthaica. They showed potent in vitro insulin sensitizing activity.

Covalent immobilization of porcine pancreatic lipase on carboxyl-activated magnetic nanoparticles: Characterization and application for enzymatic inhibition assays

Co-reporter:Yuan-Ting Zhu, Xiao-Yun Ren, Yi-Ming Liu, Ying Wei, Lin-Sen Qing, Xun Liao

Materials Science and Engineering: C 2014 Volume 38() pp:278-285

Publication Date(Web):1 May 2014

DOI:10.1016/j.msec.2014.02.011

•Porcine pancreatic lipase was firstly covalently immobilized onto carboxylated MNPs.•Immobilized porcine pancreatic lipase (PPL) was characterized by various techniques.•MNPs-PPL showed higher activity, reusability, and thermo-stability than the free PPL.•Immobilized PPL showed promising potential in screening for lipase inhibitors.Using carboxyl functionalized silica-coated magnetic nanoparticles (MNPs) as carrier, a novel immobilized porcine pancreatic lipase (PPL) was prepared through the 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) coupling reaction. Transmission electron microscopic images showed that the synthesized nanoparticles (Fe3O4–SiO2) possessed three dimensional core–shell structures with an average diameter of ~ 20 nm. The effective enzyme immobilization onto the nanocomposite was confirmed by atomic force microscopic (AFM) analysis. Results from Fourier-transform infrared spectroscopy (FT-IR), Bradford protein assay, and thermo-gravimetric analysis (TGA) indicated that PPL was covalently attached to the surface of magnetic nanoparticles with a PPL immobilization yield of 50 mg enzyme/g MNPs. Vibrating sample magnetometer (VSM) analysis revealed that the MNPs-PPL nanocomposite had a high saturation magnetization of 42.25 emu·g− 1. The properties of the immobilized PPL were investigated in comparison with the free enzyme counterpart. Enzymatic activity, reusability, thermo-stability, and storage stability of the immobilized PPL were found significantly superior to those of the free one. The Km and the Vmax values (0.02 mM, 6.40 U·mg− 1 enzyme) indicated the enhanced activity of the immobilized PPL compared to those of the free enzyme (0.29 mM, 3.16 U·mg− 1 enzyme). Furthermore, at an elevated temperature of 70 °C, immobilized PPL retained 60% of its initial activity. The PPL-MNPs nanocomposite was applied in the enzyme inhibition assays using orlistat, and two natural products isolated from oolong tea (i.e., EGCG and EGC) as the test compounds.

Rapid Magnetic Solid-Phase Extraction for the Selective Determination of Isoflavones in Soymilk Using Baicalin-Functionalized Magnetic Nanoparticles

Co-reporter:Lin-Sen Qing, Ying Xue, Yi-Ming Liu, Jian Liang, Jing Xie, and Xun Liao

Journal of Agricultural and Food Chemistry 2013 Volume 61(Issue 34) pp:8072-8078

Publication Date(Web):July 30, 2013

DOI:10.1021/jf402097y

Most protocols of sample preparation for isoflavone determination in soymilk and other liquid soybean products involves tedious freeze-drying and time-consuming extraction procedures. We report a facile and rapid magnetic solid-phase extraction (MSPE) of isoflavones from soymilk for subsequent high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) analysis. The extraction was based on the selective binding of isoflavones to baicalin-functionalized core–shell magnetic nanoparticles (BMNPs). The proposed MSPE-HPLC-MS/MS analytical method had a linear calibration curve in the concentration range from 0.3 to 80 mg/L isoflavones. With the use of calycosin, an isomer of one of the isoflavones targeted as an internal standard, interday (5 days) precisions of the slope and intercept of the calibration curves were found to be in the range between 2.5% and 3.6% (RSD, n = 5). Six isoflavones, that is, daidzein, glycitein, genistein, daidzin, glycitin, and genistin were detected in commercial soymilk samples and quantified by the proposed analytical method. The results indicated that the method was useful for fast determination of isoflavones in soymilk and other liquid soybean products.

Selective extraction of flavonoids from Ginkgo biloba leaves using human serum albumin functionalized magnetic nanoparticles

Co-reporter:Xiao-Yun Ren, Ying Xue, Jian Liang, Li-Sheng Ding, Xun Liao

Chinese Chemical Letters 2013 Volume 24(Issue 12) pp:1099-1102

Publication Date(Web):December 2013

DOI:10.1016/j.cclet.2013.07.002

In a novel procedure, human serum albumin functionalized magnetic nanoparticles (HSA-MNPs) were used to selectively extract nine flavonoids in the extract of Ginkgo biloba leaves. The chemical structures of those flavonoids were characterized with high performance liquid chromatography coupled with mass spectrometry (HPLC–MS). The selective extraction with HSA-MNPs coupled with structural elucidation with HPLC–MS shows powerful potential for analysis of bioactive components in traditional Chinese medicines.Human serum albumin functionalized magnetic nanoparticles were used to extract selectively the flavonoids presented in the leaves of Ginkgo biloba, and the chemical structures of the flavonoids were characterized with HPLC–MS.

Identification of flavonoid glycosides in Rosa chinensis flowers by liquid chromatography–tandem mass spectrometry in combination with 13C nuclear magnetic resonance

Co-reporter:Lin-Sen Qing, Ying Xue, Jian-Guang Zhang, Zhi-Feng Zhang, Jian Liang, Yan Jiang, Yi-Ming Liu, Xun Liao

Journal of Chromatography A 2012 Volume 1249() pp:130-137

Publication Date(Web):3 August 2012

DOI:10.1016/j.chroma.2012.06.013

Flowers of Rosa chinensis are widely used in traditional Chinese medicine as well as in food industry. Flavonoid glycosides are believed to be the major components in R. chinensis that are responsible for its antioxidant activities. In this work, a liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method was developed for analysis of flavonoid glycosides presented in ethyl acetate extract of dried R. chinensis flowers. Twelve flavonoid glycosides were separated and detected. By comparing the retention times, UV spectra, and tandem MS fragments with those of respective authentic compounds, eight flavonoid glycosides were unequivocally identified. Although the other four were also identified as flavonoid glycosides, the glycosylation positions could not be determined due to lack of authentic compounds. Fortunately, the glycosylation effects were clearly observed in the 13C NMR spectrum of the extract. The detailed structural information was, therefore, obtained to identify the four flavonoid glycosides as quercetin-3-O-d-glucoside, quercetin-3-O-d-xyloside, kaempferol-3-O-d-xyloside and quercetin-3-O-d-(6″-coumaroyl)-galactoside. These flavonoid glycosides were detected and identified for the first time in this botanic material. This work reports on the first use of 13C NMR of a mixture to enhance a rapid HPLC–MS/MS analysis. The proposed analytical protocol was validated with a mixture of authentic flavonoid glycosides.Highlights► An HPLC–MS/MS method for separating flavonoid glycosides. ► Profile of flavonoid glycosides in flowers of Rosa chinensis. ► Chemical identification using HPLC–MS/MS, TLC, and 13C NMR data in combination. ► MS/MS CID fragmentation pathways for flavonoid glycosides. ► 13C NMR characteristics of flavonoid glycosides.

Identification of enzyme inhibitors using therapeutic target protein–magnetic nanoparticle conjugates

Co-reporter:Lin-Sen Qing, Nan Tang, Ying Xue, Jian Liang, Yi-Ming Liu and Xun Liao

Analytical Methods 2012 vol. 4(Issue 6) pp:1612-1615

Publication Date(Web):30 Apr 2012

DOI:10.1039/C2AY25320H

Target protein–magnetic nanoparticle (MNP) conjugates, i.e. α-glucosidase–MNP and protein tyrosine phosphatase 1B (PTP1B)–MNP, were prepared and evaluated for the first time for affinity extraction of enzyme inhibitors from herbal extracts. Four ligands extracted from Granati pericarpium were identified by ESI-MS analysis. In vitro tests indicated that they inhibited both α-glucosidase and PTP1B, two important target proteins for diabetic treatment.

Using baicalin-functionalized magnetic nanoparticles for selectively extracting flavonoids from Rosa chinensis

Co-reporter:Lin-Sen Qing;Jing Xiong;Ying Xue;Yi-Ming Liu;Bin Guang;Li-Sheng Ding

Journal of Separation Science 2011 Volume 34( Issue 22) pp:3240-3245

Publication Date(Web):

DOI:10.1002/jssc.201100578

Abstract

An extraction agent featuring a natural product, baicalin, anchored on the surface of nanomagnetic particles (BMNPs) is herein reported. A facile solid-phase extraction (SPE) procedure with high selectivity toward flavonoids using BMNPs has been established. BMNPs were proven very effective for enriching flavonoids from extracts of medicinal plants such as Rosa chinensis. The SPE protocol involving a convenient solid–liquid separation by using an external magnet field was easy to carry out. Further, the SPE sorbent (BMNPs) could be reused for many times reducing the operation cost. Importantly, flavonoids retained on the BMNPs were effectively recovered by eluting with methanol. Coupling the proposed SPE with ESI-MS/MS allowed a quick quantification of flavonoids in herbal extracts. Simultaneous determination of eight flavonoids extracted from R. chinensis was demonstrated in this work.

Magnetism-assisted modification of screen printed electrode with magnetic multi-walled carbon nanotubes for electrochemical determination of dopamine

Co-reporter:Yong-Mei Zhang, Pei-Li Xu, Qiong Zeng, Yi-Ming Liu, Xun Liao, Mei-Fang Hou

Materials Science and Engineering: C (1 May 2017) Volume 74() pp:

Publication Date(Web):1 May 2017

DOI:10.1016/j.msec.2017.01.005

•The mMWCNTs were magnetically immobilized onto SPE in a simple and fast way.•The mMWCNTs/SPE showed high synergic effect toward DA oxidation.•The negatively charged mMWCNTs can eliminate interference raised by AA.A simple and sensitive dopamine (DA) electrochemical sensor was fabricated based on magnetism-assisted modification of screen printed electrode (SPE) with magnetic multi-walled carbon nanotubes (mMWCNTs). The mMWCNTs modified electrodes (mMWCNTs/SPE) combines the advantages of SPE and the simultaneous contribution of magnetic nanoparticles (MNPs) and MWCNTs, increasing sensitivity and selectivity of DA detection. The linearity was found between 5 μM to 180 μM, with the limit of detection (LOD) of 0.43 μM. In the mean time, this modified electrode exhibited excellent selectivity for DA detection with almost no interference from ascorbic acid (AA), which co-exists with DA in many bio-samples and causes common interference. Finally, this novel electrode has been applied to determine DA concentration in spiked human blood serum and satisfactory recovery was found in the range of 97.43–102.94% with the RSDs of less than 2.27%. This work developed a sensitive and reliable electrochemical analytical method based on mMWCNTs/SPE, which exhibits great potential for diagnosis of the diseases related to DA.

Identification of enzyme inhibitors using therapeutic target protein–magnetic nanoparticle conjugates

Co-reporter:

Analytical Methods (2009-Present) 2012 - vol. 4(Issue 6) pp:

Publication Date(Web):

DOI:10.1039/C2AY25320H